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All Texas. What?
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All Texas. All Texas, yes, I know.
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[USTINOV CHUCKLES]
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00:00:45,321 --> 00:00:47,219
Might care to
look at that, Peter.
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00:00:47,254 --> 00:00:49,221
What is it? Oh...
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00:01:11,899 --> 00:01:15,799
USTINOV: [AS EINSTEIN]
"The essence of a man
like me lies just in
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"what he thinks
and how he thinks,
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"not in what
he does or suffers."
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00:01:24,877 --> 00:01:27,442
USTINOV: The time had
come for the rank amateur
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00:01:27,466 --> 00:01:31,021
to try to grasp the
way Einstein thought.
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00:01:31,056 --> 00:01:33,817
Yes, said Nigel
Calder, the writer,
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00:01:33,886 --> 00:01:37,452
my journey was really necessary.
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00:01:37,476 --> 00:01:39,823
There's the observatory now.
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00:01:39,892 --> 00:01:43,413
USTINOV: What,
those two little white
whatever they are?
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00:01:43,448 --> 00:01:45,070
NIGEL CALDER: That's right.
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00:01:45,105 --> 00:01:46,806
USTINOV: Well, the third
one I can see now.
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00:01:46,830 --> 00:01:48,453
CALDER: Yes,
they're the domes.
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00:01:54,217 --> 00:01:56,461
CALDER: They, uh, keep
a look out for aircraft
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00:01:56,495 --> 00:01:59,188
so as not to zap us
with their laser beam.
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00:02:00,430 --> 00:02:03,675
Are you serious? Quite serious.
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00:02:03,744 --> 00:02:07,482
USTINOV: They wanted me to
speak Einstein's words and
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00:02:07,506 --> 00:02:11,476
make the odd space flight,
but mostly just to attend to
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00:02:11,510 --> 00:02:13,581
the theory of relativity.
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00:02:13,616 --> 00:02:16,964
I was promised a tale of
how our perceptions of space
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00:02:16,998 --> 00:02:20,312
and time and color are distorted
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00:02:20,347 --> 00:02:23,143
according to where we are
and how we're traveling.
29
00:02:25,179 --> 00:02:28,503
Amid such relativity,
Einstein found
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00:02:28,527 --> 00:02:32,669
reliable laws governing
atoms, planets, stars
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00:02:32,738 --> 00:02:34,671
and all creation.
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00:02:39,159 --> 00:02:43,128
Ah yes, an escort. Perhaps
to make quite sure I didn't
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00:02:43,163 --> 00:02:48,409
funk the cerebral adventure
they had in store for me. Hmm.
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00:02:50,791 --> 00:02:53,528
Very nice flying.
Thank you very much indeed.Thanks.
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00:02:53,552 --> 00:02:56,624
USTINOV: On my arrival,
I knew only that
Albert Einstein was
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00:02:56,659 --> 00:02:59,972
a gentle genius whose
reasoning anticipated
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00:03:00,007 --> 00:03:03,010
our world of
nuclear energy
and space flight.
38
00:03:03,044 --> 00:03:06,669
The Big Bang. The black hole.
39
00:03:06,703 --> 00:03:08,774
Things I'd only heard about.
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00:03:20,476 --> 00:03:23,030
USTINOV: My tutors were
to be leading experts,
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00:03:23,064 --> 00:03:27,379
assembled in this
remote corner of Texas,
for my benefit,
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00:03:27,414 --> 00:03:28,932
and of yours.
43
00:03:29,001 --> 00:03:32,557
Our guides through
Einstein's Universe.
44
00:03:34,835 --> 00:03:37,182
CALDER: Dennis Sciama,
here, is a theorist
45
00:03:37,217 --> 00:03:40,575
concerned with the overall
nature of the universe.
46
00:03:40,599 --> 00:03:43,568
Roger Penrose,
he pioneered the
modern theory
47
00:03:43,602 --> 00:03:45,397
of black holes.
You've heard of them.
48
00:03:45,432 --> 00:03:46,581
USTINOV: Yes, yes, I have,
49
00:03:46,605 --> 00:03:48,780
without understanding
what they are.
50
00:03:48,849 --> 00:03:51,127
CALDER: Well John Wheeler,
here, said they had to exist
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00:03:51,196 --> 00:03:53,750
and named them black
holes as a matter of fact.
52
00:03:53,785 --> 00:03:56,960
He's very much a grand old
man of theoretical physics.
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00:03:57,029 --> 00:03:59,963
USTINOV: I see. Oh, there's
some more... Oh, yes.
54
00:04:00,032 --> 00:04:03,598
CALDER: And Wallace Sargent,
here, thinks he's discovered
a huge black hole.
55
00:04:03,622 --> 00:04:04,944
USTINOV: Well he looks
as if he's photographed
56
00:04:04,968 --> 00:04:06,936
just at the moment of
discovery, doesn't he?
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00:04:06,970 --> 00:04:09,604
CALDER: Quite pleased
with himself. Yeah, with everything.
58
00:04:09,628 --> 00:04:12,435
CALDER: Uh, Irwin Shapiro,
you'll hear how he's been
59
00:04:12,459 --> 00:04:15,610
getting radar echoes
from the planets. USTINOV: Yes.
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00:04:15,634 --> 00:04:18,292
CALDER: And Sidney Drell's
a theorist from the
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00:04:18,361 --> 00:04:21,433
high speed world of
subatomic particles.
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00:04:21,468 --> 00:04:24,447
USTINOV: Gracious! And Ken Brecher,
here, he's checked
63
00:04:24,471 --> 00:04:26,196
some of Einstein's
basic assumptions
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00:04:26,231 --> 00:04:29,855
with very precise
astronomical tests.
65
00:04:29,924 --> 00:04:35,275
USTINOV: A formidable range
of expertise but they, uh,
they look friendly enough.
66
00:04:38,312 --> 00:04:40,107
I then became aware
that there might be
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00:04:40,141 --> 00:04:43,628
more to those motorcycles
than met the eye.
68
00:04:44,145 --> 00:04:45,630
[ENGINES BLARING]
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00:05:01,508 --> 00:05:03,717
[HIGH PITCHED WHINE]
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00:05:11,932 --> 00:05:13,668
USTINOV: As we journeyed
into the mountains,
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00:05:13,692 --> 00:05:17,524
Calder told me that
the Theory of Relativity
burst upon the world
72
00:05:17,593 --> 00:05:20,112
more than 70 years ago
73
00:05:20,147 --> 00:05:22,770
when Special Relativity
proclaimed
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00:05:22,805 --> 00:05:26,049
the curious effects of
high-speed motion.
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00:05:26,118 --> 00:05:29,052
General Relativity,
he said, followed later
76
00:05:29,121 --> 00:05:31,676
as Einstein's Theory of Gravity.
77
00:05:34,817 --> 00:05:37,026
But we were to take them
in the reverse order and
78
00:05:37,060 --> 00:05:40,212
approach the bewildering
distortions of time
79
00:05:40,236 --> 00:05:43,998
by way of
a gravitational black hole.
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00:05:49,072 --> 00:05:53,663
I'm just nosing in towards
the black hole... now.
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00:06:02,845 --> 00:06:06,538
USTINOV: For our celebration
of Einstein's Relativity
82
00:06:06,573 --> 00:06:10,093
and the famous formula
that powers the universe,
83
00:06:10,162 --> 00:06:14,512
the venue was the
McDonald Observatory
of the University of Texas
84
00:06:14,546 --> 00:06:19,724
and the observatory's main
telescope was our window
on Einstein's universe.
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00:06:22,485 --> 00:06:24,453
[MACHINERY WHIRRING]
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00:06:24,522 --> 00:06:27,904
USTINOV: With a light
gathering mirror a
107 inches wide,
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00:06:27,939 --> 00:06:30,942
it's not the largest
in the world but
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00:06:31,011 --> 00:06:34,255
a very impressive
instrument all the same.
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00:06:35,947 --> 00:06:37,673
USTINOV: Oh, it's
charming. Isn't it though?
90
00:06:37,707 --> 00:06:38,915
Yes. Quite a telescope.
91
00:06:40,952 --> 00:06:46,302
USTINOV: Already I found
a posse of relativists
at my shoulder
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00:06:46,371 --> 00:06:49,443
and affording us the use of
the telescope to embellish
93
00:06:49,478 --> 00:06:53,413
our little seminar was the
director of the observatory,
Harlan Smith.
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00:06:56,416 --> 00:06:58,083
HARLAN SMITH: See the
gigantic counterweight here.
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00:06:58,107 --> 00:06:59,660
USTINOV: That's merely
a counterweight?
96
00:06:59,729 --> 00:07:02,732
Yes, many people ask
what that's for but
it's just dead weight.
97
00:07:02,767 --> 00:07:06,391
USTINOV: The air was decidedly
thin on the mountain top.
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00:07:06,426 --> 00:07:11,638
They bring you up here,
getting you in some sense
closer to the stars I suppose,
99
00:07:11,707 --> 00:07:15,469
and then present you with
stairways at every turn.
100
00:07:15,538 --> 00:07:17,609
More steps? More steps.
101
00:07:21,475 --> 00:07:24,420
You're standing very close
to one of the portholes
which the light can emerge.
102
00:07:24,444 --> 00:07:27,619
We can put an instrument on
there to analyze the light.
103
00:07:27,654 --> 00:07:30,173
Becomes a main
collecting mirror.
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00:07:30,242 --> 00:07:33,349
But it's also interesting
to see the control console
down there.
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00:07:33,418 --> 00:07:35,569
It's really remarkably small
for all the functions it does.
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00:07:35,593 --> 00:07:36,880
USTINOV: You mean that's
the dashboard for this?
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00:07:36,904 --> 00:07:38,319
SMITH: That's all it takes.
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00:07:41,461 --> 00:07:44,015
Well this is McDonald and this
kit peak. This one...
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00:07:44,084 --> 00:07:47,363
USTINOV: They did everything
to help a greenhorn understand
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00:07:47,432 --> 00:07:50,953
modern astronomy in
it's Einsteinian modes.
111
00:07:50,987 --> 00:07:54,715
SHAPIRO: And that's a tracking
station in Madrid,
the Bond telescope...
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00:07:54,784 --> 00:07:58,374
USTINOV: So basic are
Einstein's ideas to
modern knowledge
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00:07:58,443 --> 00:08:01,653
that confirming them is
now a global industry.
114
00:08:04,553 --> 00:08:07,521
When I prowled through
the observatory it seemed
like a set
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00:08:07,590 --> 00:08:12,112
for some drama in space,
and in a sense it was.
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00:08:14,183 --> 00:08:18,394
About science, Einstein and
I had only this in common,
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00:08:18,463 --> 00:08:22,398
we both hated the way
it was taught to us at school.
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00:08:22,467 --> 00:08:24,987
He transcended that...
I drowned in it.
119
00:08:26,885 --> 00:08:30,855
John Wheeler began
my rather belated rescue.
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00:08:30,889 --> 00:08:33,202
Thanks to you not
being a scientist,
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00:08:33,236 --> 00:08:35,653
we're all going to
have to give this account
122
00:08:35,687 --> 00:08:39,208
the simplicity
that Einstein would
have loved.
123
00:08:40,347 --> 00:08:42,383
Where do you think we
should the account, John?
124
00:08:42,452 --> 00:08:43,533
With gravity?
125
00:08:43,557 --> 00:08:45,052
Nothing could be better.
126
00:08:45,076 --> 00:08:48,182
Everyone has to deal
with it every day.
127
00:08:48,217 --> 00:08:49,425
Gravity.
128
00:08:49,494 --> 00:08:52,566
Well let's see what the
astronauts made of gravity
129
00:08:52,635 --> 00:08:53,774
on the moon.
130
00:08:54,913 --> 00:08:56,926
[PROJECTOR WHIRRING]
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00:08:56,950 --> 00:09:01,851
DAVE SCOTT: I'm very proud
to have the opportunity here
to play postman.
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00:09:01,886 --> 00:09:06,649
What could be a better place
to cancel a stamp than right
here at Hadley Rille.
133
00:09:06,684 --> 00:09:08,789
I, I remember this
from the time...
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00:09:10,515 --> 00:09:13,691
Now in my left hand
I have a feather...
135
00:09:13,725 --> 00:09:15,762
In my right hand a hammer.
136
00:09:15,831 --> 00:09:17,557
I guess one of the reasons, uh,
137
00:09:17,591 --> 00:09:19,258
we got got here today
was because of a
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00:09:19,282 --> 00:09:21,940
gentleman named Galileo,
a long time ago,
139
00:09:22,009 --> 00:09:24,425
who made a rather
significant discovery
140
00:09:24,460 --> 00:09:27,187
about falling objects
in gravity fields.
141
00:09:27,221 --> 00:09:31,122
And we thought that
where would be a better
place to confirm his
142
00:09:31,191 --> 00:09:34,366
findings than on the moon.
143
00:09:34,401 --> 00:09:37,231
And, uh, so, we thought
we'd try it here for you.
144
00:09:37,266 --> 00:09:40,441
And the feather happens
to be, appropriately,
a falcon feather
145
00:09:41,442 --> 00:09:43,110
for our falcon.
146
00:09:43,134 --> 00:09:46,113
And I'll drop the two of
them here and hopefully
147
00:09:46,137 --> 00:09:48,553
they'll hit the ground
at the same time.
148
00:09:50,106 --> 00:09:51,418
How about that?
149
00:09:52,971 --> 00:09:56,941
I have here a hammer
and a bird's feather.
150
00:10:00,392 --> 00:10:02,118
How about that?
151
00:10:02,187 --> 00:10:04,396
[LAUGHTER]
152
00:10:05,466 --> 00:10:07,572
WHEELER: If you were Galileo,
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00:10:07,607 --> 00:10:10,793
how would you in the light
of that, try to persuade
154
00:10:10,817 --> 00:10:13,105
people that everything
falls at the same rate?
155
00:10:13,129 --> 00:10:14,475
USTINOV: Difficult.
156
00:10:14,510 --> 00:10:18,973
WHEELER: Difficult.
Air resistance is a
whole problem isn't it?
157
00:10:18,997 --> 00:10:22,000
So it's such a
wonderful thing
that air resistance
158
00:10:22,069 --> 00:10:25,486
for objects like this
doesn't count so much.
159
00:10:29,076 --> 00:10:30,457
USTINOV: Fantastic.
160
00:10:30,491 --> 00:10:33,494
WHEELER: What a feat
for Galileo to realize
161
00:10:33,529 --> 00:10:36,981
that everything falls
at the same rate.
162
00:10:37,015 --> 00:10:40,018
But for Einstein it
was a still greater
163
00:10:40,087 --> 00:10:43,504
act of imagination to realize
164
00:10:43,539 --> 00:10:45,541
that the reason those
things all move the same,
165
00:10:45,610 --> 00:10:49,176
they get their moving orders
from the same piece of space,
166
00:10:49,200 --> 00:10:50,580
it's not the distant Earth,
167
00:10:50,615 --> 00:10:52,168
it's the space right
where they are.
168
00:10:53,825 --> 00:10:58,530
"There came to me the
happiest thought of my life.
169
00:10:58,554 --> 00:11:01,971
"Consider someone in
free fall, for example,
170
00:11:03,145 --> 00:11:05,147
"from the roof of a house.
171
00:11:05,181 --> 00:11:08,678
"There exists for
him during his fall
172
00:11:08,702 --> 00:11:12,085
"no gravitational field."
173
00:11:14,225 --> 00:11:20,552
And Einstein really
tells us that gravity
is an illusion.
174
00:11:20,576 --> 00:11:24,442
I can toss,
across to Dennis,
a ball
175
00:11:26,582 --> 00:11:30,620
and that arc looks as real
as anything could be.
176
00:11:30,655 --> 00:11:33,703
And I can toss a ball
across to Sid
177
00:11:33,727 --> 00:11:37,248
and the arc looks as
real as anything could be.
178
00:11:37,317 --> 00:11:41,183
But Einstein tells us that
the arc is a pure illusion.
179
00:11:41,217 --> 00:11:44,324
If we could only cut away
180
00:11:44,358 --> 00:11:48,466
this grid with a welder's
torch from underneath us
181
00:11:48,500 --> 00:11:50,157
and all fall freely,
182
00:11:50,192 --> 00:11:52,677
then, as I toss that
ball, it would
183
00:11:52,712 --> 00:11:55,542
move in a beautiful
straight line.
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00:11:55,576 --> 00:11:58,441
Einstein tells us
that in a local,
185
00:11:58,510 --> 00:12:02,031
freely falling frame,
there is no gravity.
186
00:12:08,244 --> 00:12:13,916
WHEELER: Einstein would
have loved to see those
astronauts in Skylab.
187
00:12:13,940 --> 00:12:17,322
They were weightless.
They were in free fall.
188
00:12:21,292 --> 00:12:24,191
Einstein's great idea,
189
00:12:24,226 --> 00:12:26,262
all objects fall
190
00:12:26,297 --> 00:12:29,749
because they get their moving
orders right from space.
191
00:12:32,959 --> 00:12:38,378
Skylab had no power in orbit
and no force acted on it.
192
00:12:38,412 --> 00:12:42,071
It went just as straight
as possible through space.
193
00:12:43,245 --> 00:12:47,594
But space is warped
around the earth.
194
00:12:47,628 --> 00:12:51,771
So Skylab could end up and
did end up going in a circle.
195
00:12:53,876 --> 00:12:58,605
Warped space was
Einstein's style of thinking.
196
00:13:01,470 --> 00:13:03,713
Moving about in warped space
197
00:13:03,748 --> 00:13:06,623
is no more mysterious
than traveling
198
00:13:06,647 --> 00:13:09,443
about in these mountains.
199
00:13:09,478 --> 00:13:12,861
You just can't go
in a straight line.
200
00:13:12,930 --> 00:13:16,485
To go in a straight line you
must go down on the plain.
201
00:13:18,245 --> 00:13:20,489
USTINOV: Well, like everything
else, light, it seems,
202
00:13:20,558 --> 00:13:22,156
responds to gravity.
203
00:13:22,180 --> 00:13:24,769
And so space is warped.
204
00:13:24,804 --> 00:13:29,370
Coaxing me over that
fence was Irwin Shapiro.
205
00:13:29,394 --> 00:13:33,019
SHAPIRO: One of the important
questions we have to decide
is whether something
206
00:13:33,088 --> 00:13:35,504
is straight or warped.
How can we do that?
207
00:13:35,538 --> 00:13:37,437
We need some frame of reference.
208
00:13:37,471 --> 00:13:39,370
For example,
if you were to look at
209
00:13:39,439 --> 00:13:42,545
this line of posts
and trying to decide
210
00:13:42,614 --> 00:13:44,834
whether they were straight
or not, how would you do it?
211
00:13:44,858 --> 00:13:47,516
Well, you'd presumably,
look along it.
212
00:13:47,550 --> 00:13:50,519
I think I could have
told from there but
it's almost straight.
213
00:13:50,553 --> 00:13:53,015
Right. You squinted
along it and really,
214
00:13:53,039 --> 00:13:56,190
your frame of reference
was the light rays
215
00:13:56,214 --> 00:14:00,367
and that's a very good
technique, however you
can get fooled
216
00:14:00,391 --> 00:14:03,049
if the light itself gets bent.
217
00:14:03,118 --> 00:14:05,534
For example, water bends light
218
00:14:05,568 --> 00:14:10,470
and we can illustrate that
here with these two rulers.
I put these two rulers
219
00:14:10,504 --> 00:14:12,852
in the water and ask
you to decide whether
220
00:14:12,886 --> 00:14:15,716
the bottom one or the top
one is actually straight.
221
00:14:15,785 --> 00:14:18,547
Well, since water bends light,
222
00:14:18,581 --> 00:14:21,136
the bottom one looks straight
and obviously isn't.
223
00:14:21,170 --> 00:14:23,310
That's right.
See, when we pull it out,
224
00:14:23,345 --> 00:14:25,357
when they're out of the water,
you can see clearly that the
225
00:14:25,381 --> 00:14:29,523
bottom one is the one
that's bent and the top
one is the straight one.
226
00:14:34,874 --> 00:14:40,258
SHAPIRO: In fact, if you look
from the earth at light from
a star beyond the sun,
227
00:14:40,293 --> 00:14:44,642
the sun's gravity bends
the light of the star as
it grazes it's limb.
228
00:14:47,783 --> 00:14:52,408
And so, the position of the
star appears to change.
229
00:14:54,686 --> 00:14:57,379
Einstein calculated
the bending of light
230
00:14:57,413 --> 00:14:59,899
using this idea of curved space.
231
00:15:01,590 --> 00:15:04,213
As seen from the earth,
232
00:15:04,248 --> 00:15:09,563
certain fixed stars appear
to be in the neighborhood
of the sun
233
00:15:09,598 --> 00:15:14,303
and can be observed during
a total eclipse of the sun.
234
00:15:14,327 --> 00:15:18,617
At such times these stars
ought to appear to be
displaced outwards
235
00:15:18,641 --> 00:15:23,277
from the sun as compared
with their apparent
position in the sky when
236
00:15:23,301 --> 00:15:27,202
the sun is situated at another
part of the heavens.
237
00:15:27,236 --> 00:15:32,069
A ray of light going past the
sun undergoes a deflection of
238
00:15:32,103 --> 00:15:35,348
1.7 seconds of arc.
239
00:15:36,211 --> 00:15:39,214
That prediction, in 1915,
240
00:15:39,248 --> 00:15:41,975
led to world fame for Einstein.
241
00:15:42,010 --> 00:15:47,670
In fact, there was a total
eclipse of the sun in 1919
242
00:15:47,739 --> 00:15:49,821
and a team of
British astronomers
243
00:15:49,845 --> 00:15:53,297
went to observe this total
eclipse in the tropics.
244
00:15:53,331 --> 00:15:57,484
And here's a plate taken
from that expedition,
245
00:15:57,508 --> 00:16:01,167
of the sun during
the total eclipse.
This is a negative
246
00:16:01,236 --> 00:16:03,065
so you don't see the sun at all,
247
00:16:03,100 --> 00:16:04,456
it's a blank field... USTINOV: Yeah.
248
00:16:04,480 --> 00:16:07,587
...and these
black striations are
the solar corona.
249
00:16:08,726 --> 00:16:10,900
And very tiny black dots
250
00:16:10,935 --> 00:16:13,800
are the stars in
the field of view.
251
00:16:13,834 --> 00:16:16,768
And the relative positions
of these stars were
252
00:16:16,803 --> 00:16:20,910
measured very accurately
and compared with
corresponding measurements
253
00:16:20,945 --> 00:16:23,510
of a photograph taken
of the same stars
254
00:16:23,534 --> 00:16:26,157
when the sun wasn't
in the field of view
255
00:16:26,192 --> 00:16:29,160
and the results showed
the star positions shifted
256
00:16:29,195 --> 00:16:31,507
during the total eclipse
257
00:16:31,542 --> 00:16:34,441
in approximate agreement
with Einstein's predictions
258
00:16:34,476 --> 00:16:36,340
and certainly quite different
259
00:16:36,374 --> 00:16:39,515
from what Newton
would have predicted.Oh.
260
00:16:41,310 --> 00:16:43,519
EINSTEIN: Newton, forgive me.
261
00:16:43,554 --> 00:16:47,361
You found the only path
barely open in your time
262
00:16:47,385 --> 00:16:51,883
for a man of the
highest powers of
thought and ordering.
263
00:16:51,907 --> 00:16:56,187
The concepts which you created
still guide our thinking in
264
00:16:56,222 --> 00:17:00,467
physics even today
although we now know
265
00:17:00,502 --> 00:17:03,677
that they will have to
be replaced by others,
266
00:17:03,712 --> 00:17:07,336
farther removed from the
realm of direct experience,
267
00:17:07,371 --> 00:17:12,824
if we aim at a deeper
understanding of
relationships.
268
00:17:18,175 --> 00:17:22,351
SHAPIRO: Nowadays, we
needn't await a total
eclipse of the sun
269
00:17:22,386 --> 00:17:25,699
to attempt to make
measurements of the
deflection of light,
270
00:17:25,734 --> 00:17:27,839
we can use radio waves.
271
00:17:27,874 --> 00:17:29,876
According to Einstein's theory,
272
00:17:29,910 --> 00:17:32,361
radio waves, just like light and
273
00:17:32,396 --> 00:17:35,226
x-rays or any other
light-like radiation,
274
00:17:35,261 --> 00:17:40,104
is predicted to behave
the same way under the
influence of gravity.
275
00:17:40,128 --> 00:17:42,785
SHAPIRO: Instead of ordinary
stars in our galaxy,
276
00:17:42,854 --> 00:17:47,928
with radio waves we observe
the much more distant
objects called quasars.
277
00:17:48,860 --> 00:17:50,907
Just like the visible stars,
278
00:17:50,931 --> 00:17:52,944
quasars seem to change position
279
00:17:52,968 --> 00:17:56,040
in the sky when the sun
comes into line with them.
280
00:17:59,526 --> 00:18:01,435
With the radio technique,
281
00:18:01,459 --> 00:18:05,118
we can also achieve
far better accuracy.
282
00:18:05,187 --> 00:18:07,086
The most accurate
measurements were done
283
00:18:07,120 --> 00:18:11,963
at the National Radio
Astronomy Observatory in
Greenbank, West Virginia.
284
00:18:11,987 --> 00:18:15,922
This experiment confirmed
Einstein's prediction
for the bending
285
00:18:15,956 --> 00:18:17,855
to within about one percent.
286
00:18:20,375 --> 00:18:22,974
[CHUCKLING]
287
00:18:22,998 --> 00:18:26,415
USTINOV: Powerless, then,
to question that gravity
bends light,
288
00:18:26,450 --> 00:18:30,281
we tried our skills with
an impressionistic
model of warped space.
289
00:18:32,973 --> 00:18:34,986
They urged me to
believe that the
290
00:18:35,010 --> 00:18:39,083
distortions of space due to
a massive body like the sun
291
00:18:39,118 --> 00:18:42,604
could shape the course
of lesser objects like
the planets.
292
00:18:43,915 --> 00:18:45,952
The table maker
gratuitously added
293
00:18:45,986 --> 00:18:48,092
bottomless pits of gravity,
294
00:18:48,127 --> 00:18:52,786
black holes that would
swallow an unskillful ball.
295
00:18:53,339 --> 00:18:54,547
[CLUNKING]
296
00:19:03,590 --> 00:19:06,835
WHEELER: Black holes aren't
getting much to eat today.
297
00:19:08,526 --> 00:19:11,633
Einstein wouldn't
be happy if we didn't tell
you his story
298
00:19:11,667 --> 00:19:14,187
in the simplest words.
299
00:19:14,222 --> 00:19:20,331
Space tells matter how
to move and matter tells
space how to curve.
300
00:19:20,952 --> 00:19:22,989
That's it.
301
00:19:23,023 --> 00:19:26,958
Throw this ball past the sun.
302
00:19:30,376 --> 00:19:31,687
That's light
303
00:19:31,756 --> 00:19:34,242
changing its direction,
304
00:19:34,311 --> 00:19:38,315
but not through some
mysterious force
acting through space
305
00:19:38,349 --> 00:19:41,663
but through the
warping of space itself.
306
00:19:42,836 --> 00:19:45,839
Or put a planet
307
00:19:45,874 --> 00:19:51,190
into orbit around the
sun and watch it go.
308
00:19:51,224 --> 00:19:54,331
And where does it get
it's moving orders from?
309
00:19:54,365 --> 00:19:57,023
Not from that sun
310
00:19:57,057 --> 00:19:59,784
but from the space
right where it is.
311
00:20:03,892 --> 00:20:06,135
Or put Skylab
312
00:20:06,170 --> 00:20:09,242
into orbit around the earth
313
00:20:09,277 --> 00:20:13,315
and ask those people on
Skylab what do they see.
314
00:20:15,766 --> 00:20:18,217
They get their moving orders
315
00:20:18,251 --> 00:20:22,221
from space itself,
right there, where it is.
316
00:20:27,122 --> 00:20:31,230
Einstein's wonderfully
simple picture of it all.
317
00:20:32,576 --> 00:20:35,544
Or the moon going
around the earth.
318
00:20:38,375 --> 00:20:40,422
Pull the earth away,
319
00:20:40,446 --> 00:20:45,416
unwarp space and
the moon will fly off.
320
00:20:45,451 --> 00:20:49,869
Happy to go in a
beautiful straight line.
321
00:20:49,903 --> 00:20:54,253
USTINOV: But cosmic
space isn't, after all,
a distorted tabletop.
322
00:20:54,287 --> 00:20:58,302
I bared my misgivings
to Dennis Sciama.
323
00:20:58,326 --> 00:21:03,503
How on earth, or rather,
how in the universe
can nothingness have shape?
324
00:21:04,470 --> 00:21:06,575
That is indeed
a difficult question
325
00:21:06,610 --> 00:21:09,451
and the Greeks struggled
with it very much.
326
00:21:09,475 --> 00:21:11,994
They had a geometry of their own
327
00:21:12,063 --> 00:21:14,100
and light, responding
to that geometry,
328
00:21:14,134 --> 00:21:16,309
would move in straight lines.
329
00:21:16,378 --> 00:21:19,554
That's not at all the
case in Einstein's theory.
330
00:21:19,588 --> 00:21:22,315
He uses a different
geometry from the Greeks.
331
00:21:22,350 --> 00:21:27,182
A geometry in which space is
warped and light responding
to that geometry
332
00:21:27,251 --> 00:21:30,161
doesn't move in straight
lines but is bent.
333
00:21:30,185 --> 00:21:32,991
And a planet responding to
that geometry would move,
334
00:21:33,015 --> 00:21:35,639
let's say, in a circle
around the sun.
335
00:21:35,673 --> 00:21:38,642
Einstein himself was very
concerned to stress
336
00:21:38,676 --> 00:21:43,405
this difference from the old
geometry and he tried to
make it plain to all of us.
337
00:21:45,200 --> 00:21:48,962
EINSTEIN: On the basis of the
general theory of relativity,
338
00:21:48,997 --> 00:21:52,656
space, as opposed
to what fills space,
339
00:21:52,690 --> 00:21:54,796
has no separate existence.
340
00:21:54,830 --> 00:21:57,661
There is no such
thing as empty space,
341
00:21:57,695 --> 00:22:02,538
that is space without
a gravitational field.
342
00:22:02,562 --> 00:22:08,499
The geometrical properties of
space are not independent but
they are determined by matter.
343
00:22:12,503 --> 00:22:18,302
USTINOV: It seemed that either
Newton's force of gravity or
Einstein's warped geometry,
344
00:22:18,337 --> 00:22:21,857
would keep the planet circling
in the same stately fashion.
345
00:22:22,548 --> 00:22:24,481
But who was right?
346
00:22:26,034 --> 00:22:27,874
SHAPIRO: In Einstein's theory,
347
00:22:27,898 --> 00:22:30,866
the orbits are predicted
to be slightly different
348
00:22:30,901 --> 00:22:33,742
than they are in
Newton's theory.
349
00:22:33,766 --> 00:22:38,736
For example, let us
consider a single planet
in orbit about the sun.
350
00:22:38,771 --> 00:22:43,672
In Newton's theory, this
planet would be predicted
to follow an elliptical path,
351
00:22:43,707 --> 00:22:47,711
that is a path sort of
like a stretched out circle.
352
00:22:47,745 --> 00:22:51,266
And in Newton's theory
this path would be
followed continually,
353
00:22:51,335 --> 00:22:56,305
ad nauseum, following
the same elliptical
path all the time.
354
00:22:59,481 --> 00:23:01,656
SHAPIRO: Whereas in
Einstein's theory,
355
00:23:01,690 --> 00:23:03,737
this path actually
swivels around.
356
00:23:03,761 --> 00:23:09,146
That is the ellipse rotates
very slowly in space.
357
00:23:11,597 --> 00:23:13,920
USTINOV: Near the sun,
gravity's a little stronger in
358
00:23:13,944 --> 00:23:16,187
Einstein's theory
than in Newton's.
359
00:23:16,222 --> 00:23:21,261
So close in, the planet
teeters for a moment
before climbing away.
360
00:23:21,296 --> 00:23:24,713
SHAPIRO: This
different prediction
of Einstein's theory
361
00:23:24,748 --> 00:23:27,923
actually cleared up a
nineteenth century mystery
362
00:23:27,958 --> 00:23:30,167
about the orbit of
the planet Mercury,
363
00:23:30,201 --> 00:23:32,801
the closest one to the sun.
364
00:23:32,825 --> 00:23:38,037
The ellipse corresponding
to the orbit of Mercury
is not stationary
365
00:23:38,071 --> 00:23:42,800
with respect to the
fixed stars, but rotates
366
00:23:42,869 --> 00:23:45,424
exceedingly slowly.
367
00:23:45,458 --> 00:23:47,471
The value obtained for this
368
00:23:47,495 --> 00:23:53,224
rotary movement is
43 seconds of arc
per century.
369
00:23:53,259 --> 00:23:56,262
This effect can be explained
370
00:23:56,296 --> 00:24:00,266
by classical mechanics only
on the assumption of
hypotheses which have
371
00:24:01,129 --> 00:24:03,062
little probability.
372
00:24:03,096 --> 00:24:07,629
[CLEARS THROAT]
On the basis of the general
theory of relativity,
373
00:24:07,653 --> 00:24:11,380
it is found that the
ellipse of every planet
374
00:24:11,415 --> 00:24:15,523
must necessarily
rotate in this manner.
375
00:24:19,492 --> 00:24:20,873
[PROJECTOR WHIRRING]
376
00:24:24,152 --> 00:24:26,361
SHAPIRO: In the late 1960s
377
00:24:26,430 --> 00:24:29,951
we used the Haystack radio
telescope in Massachusetts
378
00:24:29,985 --> 00:24:33,033
to measure the swivel
of Mercury's orbit.
379
00:24:33,057 --> 00:24:37,924
This telescope is enclosed in
a ray dome to protect it from
the wind and the sun.
380
00:24:42,377 --> 00:24:45,449
What we did was use
this radio telescope
381
00:24:45,484 --> 00:24:49,798
with an attached radar system
to send pulses of radio energy
382
00:24:49,833 --> 00:24:52,974
towards Mercury and
to detect the echoes.
383
00:24:54,596 --> 00:24:55,666
[BEEPING]
384
00:24:57,323 --> 00:25:01,465
In fact, although the power in
the transmitted radar signals
385
00:25:01,500 --> 00:25:04,054
is about 500,000 watts,
386
00:25:04,123 --> 00:25:07,851
enough to supply the
electrical needs of
a small town,
387
00:25:07,885 --> 00:25:10,129
the echo we detect is so weak
388
00:25:10,163 --> 00:25:14,547
that its power is even
less than that expended
by an average housefly
389
00:25:14,582 --> 00:25:19,725
crawling up a wall at the
rate of only a millimeter
per millennium.
390
00:25:19,794 --> 00:25:23,176
By measuring these echoes
from Mercury, periodically
391
00:25:23,211 --> 00:25:28,216
over several years,
we were able to detect the
swivel of Mercury's orbit
392
00:25:28,250 --> 00:25:33,532
because the echo delay is
different for a swiveling than
for a non-swiveling orbit.
393
00:25:35,257 --> 00:25:39,676
Our results confirmed
Einstein's prediction
to within one percent.
394
00:25:42,713 --> 00:25:44,577
[MACHINERY WHIRRING]
395
00:25:44,612 --> 00:25:47,062
There's an amazing object
that's been discovered in
396
00:25:47,097 --> 00:25:51,204
the sky that swivels in
its orbit far more than
Mercury does.
397
00:25:51,239 --> 00:25:56,427
This object illustrates
beautifully Einstein's
relativistic effect.
398
00:25:56,451 --> 00:25:59,143
The object is called
a binary pulsar.
399
00:26:01,352 --> 00:26:05,598
USTINOV: An object lying
far off among the stars,
the binary pulsar,
400
00:26:05,667 --> 00:26:07,921
was evidently quite invisible.
401
00:26:07,945 --> 00:26:12,122
By what new ingenuity
could they track its orbit?
402
00:26:12,191 --> 00:26:15,643
Kenneth Brecher
patiently explained.
403
00:26:15,712 --> 00:26:20,717
Imagine a rapidly moving
vehicle coming down the
road... A motorbike say.
404
00:26:20,751 --> 00:26:24,341
As it comes towards you,
you hear a high pitched roar.
405
00:26:24,375 --> 00:26:26,032
[ENGINE RUNNING]
406
00:26:29,518 --> 00:26:32,452
When it passes you,
the pitch drops
407
00:26:32,487 --> 00:26:34,765
with a change in frequency
according to whether
408
00:26:34,800 --> 00:26:38,124
the source of sound is coming
towards you or going away.
409
00:26:38,148 --> 00:26:40,599
That's the Doppler Effect.
410
00:26:40,633 --> 00:26:43,671
The same thing happens with
light or with radio waves.
411
00:26:45,051 --> 00:26:47,709
Police speed traps
use Doppler radar.
412
00:26:47,744 --> 00:26:49,159
It sends out radio waves that
413
00:26:49,228 --> 00:26:52,611
bounce off the vehicle
and come back with a
higher frequency.
414
00:26:52,645 --> 00:26:56,028
The faster you're going the
more the frequency is changed.
415
00:27:02,172 --> 00:27:06,625
The Doppler Effect is an
unbeatable way of measuring
relative speed.
416
00:27:08,730 --> 00:27:10,214
[BEEPING]
417
00:27:10,283 --> 00:27:13,424
Now imagine an object,
circling, giving out
its own radio pulses.
418
00:27:15,530 --> 00:27:18,992
You'd find the frequency
rising and falling repeatedly.
419
00:27:19,016 --> 00:27:21,743
You could tell it was circling
even if you couldn't see it.
420
00:27:23,503 --> 00:27:27,128
Completely out of sight
among the stars there's
an orbiting pulsar.
421
00:27:27,162 --> 00:27:29,095
It's nature's gift
to the relativist.
422
00:27:31,339 --> 00:27:34,756
A pulsar is a collapsed star,
a neutron star we call it,
423
00:27:34,791 --> 00:27:37,207
which ticks like a
very accurate clock
424
00:27:37,276 --> 00:27:40,072
emitting regular beeps
of radio energy.
425
00:27:41,694 --> 00:27:44,145
This particular pulsar
changes its beep rate
426
00:27:44,179 --> 00:27:47,458
in an eight hour cycle as it
sweeps forwards and backwards.
427
00:27:49,219 --> 00:27:52,049
But did you discover
this binary pulsar?
428
00:27:52,084 --> 00:27:55,156
No, I didn't discover the
pulsar but all of us who
are working on
429
00:27:55,190 --> 00:27:58,573
relativity and astrophysics
are incredibly excited
about it.
430
00:27:58,642 --> 00:28:01,034
It's a unique object and
a unique opportunity to
431
00:28:01,058 --> 00:28:07,075
test the laws of general
relativity in a very
precise way.
432
00:28:07,099 --> 00:28:11,482
BRECHER: It's being studied at
the Arecibo radio observatory
in Puerto Rico.
433
00:28:15,521 --> 00:28:19,743
Joe Taylor and Russell
Hulse of the University of
Massachusetts discovered it
434
00:28:19,767 --> 00:28:23,356
and Taylor has been checking
up on it every few months
ever since.
435
00:28:23,391 --> 00:28:25,393
We're right on source? Yeah.
436
00:28:25,462 --> 00:28:26,912
Following errors? No.
437
00:28:26,981 --> 00:28:28,396
Thank you. Good.Okay.
438
00:28:30,536 --> 00:28:32,096
Hello, everything still
going all right?
439
00:28:32,158 --> 00:28:35,759
Yeah, fine.
[SPEAKING INDISTINCTLY]
440
00:28:35,783 --> 00:28:40,097
BRECHER: One of the marvelous
things about it is the changes
are so predictable
441
00:28:40,132 --> 00:28:43,963
that when they switch
on the pulsar always
clocks in right on cue.
442
00:28:48,865 --> 00:28:50,280
[BEEPING]
443
00:28:50,349 --> 00:28:52,523
The pulsar is in a very tight,
fast orbit
444
00:28:52,558 --> 00:28:55,734
around another collapsed
star that's not directly
detectable.
445
00:28:57,701 --> 00:29:01,153
And the pulsar's
orbit changes in the
Einsteinian manner.
446
00:29:01,222 --> 00:29:06,399
It swivels 30,000 times faster
than Mercury's orbit does,
four degrees a year.
447
00:29:09,471 --> 00:29:13,821
CALDER: The binary pulsar's
very nice evidence
for Einstein's effect.
448
00:29:13,890 --> 00:29:17,928
But really, to milk it
for all it's worth in
confirming relativity,
449
00:29:17,963 --> 00:29:20,759
Taylor still has years
of work to do.
450
00:29:20,793 --> 00:29:24,314
SCIAMA: And in fact there's
some things still more
exciting in prospect,
451
00:29:24,383 --> 00:29:28,042
which is that as the binary
pulsar goes round,
452
00:29:28,076 --> 00:29:33,392
according to Einstein, it
radiates gravitational waves.
453
00:29:33,426 --> 00:29:38,397
The result of that would
be that the orbital period
would change slowly
454
00:29:38,431 --> 00:29:41,296
and Joe Taylor is trying
to detect this change.
455
00:29:42,470 --> 00:29:44,127
In fact, just the other day,
456
00:29:44,161 --> 00:29:47,924
Joe Taylor sent me a
new manuscript of his
in which he claims to
457
00:29:47,958 --> 00:29:52,273
begin to measure this effect
and it does seem to fit
Einstein's theory very well.
458
00:29:54,033 --> 00:29:57,588
USTINOV: These gravitational
waves that Einstein predicted
459
00:29:57,623 --> 00:30:00,671
are ripples of warped space.
460
00:30:00,695 --> 00:30:05,631
And with the help of a
computer, theorists have made
movies of gravitational waves
461
00:30:05,665 --> 00:30:08,841
that ought to pour out
from violent events
462
00:30:08,910 --> 00:30:10,947
like the collapse of a star.
463
00:30:12,845 --> 00:30:16,342
And there's an interesting
kinship, isn't there, between
gravitational waves
464
00:30:16,366 --> 00:30:19,034
and the familiar
tides of the sea
465
00:30:19,058 --> 00:30:23,235
that are raised on the
earth by the warped
space around the moon.
466
00:30:25,168 --> 00:30:29,172
We're a long way from
the sea here so we can't
actually see
467
00:30:29,206 --> 00:30:32,900
the ocean moving up and down
the way it does
in a spectacular
468
00:30:32,969 --> 00:30:37,318
fashion on the coast but,
as a matter of fact,
at this observatory
469
00:30:37,352 --> 00:30:42,806
they have measured how the
rocks of the earth move
under the moon's influence.
470
00:30:42,841 --> 00:30:48,847
They move up and down by as
much as a foot twice a day.
471
00:30:48,881 --> 00:30:52,550
USTINOV: Unsettling
to think of the earth
heaving like that.
472
00:30:52,574 --> 00:30:58,857
But the force of the tides
gave a certain palpability
to warped space.
473
00:30:58,891 --> 00:31:05,311
Wheeler then offered me a
warped miniature table and
a jar of quicksilver.
474
00:31:05,346 --> 00:31:08,487
WHEELER: You'll notice
that you have
475
00:31:08,521 --> 00:31:13,561
one of the blobs of
mercury pulled right out,
stretched out
476
00:31:13,595 --> 00:31:19,118
and nothing is a more
beautiful illustration of
a tide effect than that.
477
00:31:22,156 --> 00:31:24,503
What you can, if you'd like to,
478
00:31:24,537 --> 00:31:28,162
to illustrate that
gravitational waves
479
00:31:28,196 --> 00:31:29,898
are also tides,
480
00:31:29,922 --> 00:31:32,787
is take that blob of
mercury and jiggle it
481
00:31:32,856 --> 00:31:36,860
and you notice it changes
its shape, first this way
and then that way
482
00:31:36,895 --> 00:31:39,898
and there just isn't a more
beautiful illustration
483
00:31:39,932 --> 00:31:42,245
of what a gravitational wave is
484
00:31:42,279 --> 00:31:46,939
than the tidal stretching of
that little blob of mercury
485
00:31:46,974 --> 00:31:50,436
or the tidal stretching of a
gravitational wave detector.
486
00:31:50,460 --> 00:31:53,946
One of the things that
interests me most about
the whole thing
487
00:31:54,015 --> 00:31:56,880
is the push it's going to
give to technology,
488
00:31:56,915 --> 00:31:59,617
because looking for
gravitational waves,
489
00:31:59,641 --> 00:32:04,405
we have to get down to what
everybody calls the quantum
limit of measurement,
490
00:32:04,439 --> 00:32:06,648
and that's a new
thing in the world,
491
00:32:06,717 --> 00:32:09,237
and it's going to mean
new kinds of equipment
492
00:32:09,272 --> 00:32:10,998
that show up all over the map.
493
00:32:11,067 --> 00:32:14,933
Engineering, biology,
medicine... What have you.
494
00:32:19,661 --> 00:32:22,009
SCIAMA: You can try to detect
very slight ringing
495
00:32:22,078 --> 00:32:26,737
in great super cool metal
cylinders like the one at
Stanford in California.
496
00:32:28,153 --> 00:32:29,844
In Glasgow, they have
a different method.
497
00:32:29,913 --> 00:32:33,227
Look at some of the
details of the optical
systems down in here.
498
00:32:33,261 --> 00:32:35,884
USTINOV: Ronald Greaver
uses laser beams
499
00:32:35,919 --> 00:32:38,094
that shuttle to and
fro many times.
500
00:32:42,201 --> 00:32:45,308
And that's to measure
shifts in the position
of different masses,
501
00:32:45,342 --> 00:32:49,484
shifts that might be caused
by gravitational waves
washing through the earth.
502
00:32:54,351 --> 00:32:56,560
But it's incredibly delicate.
503
00:32:56,629 --> 00:33:01,186
They're getting ready to look
for movements far, far smaller
than the width of an atom
504
00:33:01,255 --> 00:33:02,946
between masses mounted about
505
00:33:02,981 --> 00:33:06,018
30 feet apart.
506
00:33:06,053 --> 00:33:11,206
SCIAMA: It's possible that
stars going round one another
very rapidly can be detected.
507
00:33:11,230 --> 00:33:16,546
It's possible that violently
exploding star like supernovae
will be detected
508
00:33:16,615 --> 00:33:20,515
and it's even possible that
objects falling into massive
black holes
509
00:33:20,550 --> 00:33:23,839
will produce gravitational
waves we can pick up.
510
00:33:23,863 --> 00:33:26,014
And if any of those
things happen,
511
00:33:26,038 --> 00:33:28,799
we'll be seeing the effects
Einstein predicted
512
00:33:28,834 --> 00:33:31,112
of warped space propagating
513
00:33:31,147 --> 00:33:33,011
actually with the
speed of light.
514
00:33:37,153 --> 00:33:40,397
USTINOV: The McDonald
Observatory had its
own laser
515
00:33:40,466 --> 00:33:43,987
and after hearing about clever
experiments in other places
516
00:33:44,022 --> 00:33:46,334
I was to see one
in progress myself.
517
00:33:47,335 --> 00:33:48,335
[CHUCKLING]
518
00:33:51,029 --> 00:33:53,997
CALDER: We've put those waves
of gravity behind us, Peter,
519
00:33:54,032 --> 00:33:59,175
and come back to basic issues
about gravity and orbits
and warped space.
520
00:33:59,209 --> 00:34:02,005
What they do here is shoot
their laser at the moon
521
00:34:02,040 --> 00:34:06,113
to check its distance
and movements to within
a matter of inches.
522
00:34:07,148 --> 00:34:08,884
The moon's a heavy object
523
00:34:08,908 --> 00:34:11,256
but the earth is heavier still
524
00:34:11,290 --> 00:34:15,191
and they might respond
differently in the
sun's gravity.
525
00:34:15,225 --> 00:34:19,333
Then, we might see the
moon's orbit drifting a
few feet closer to the sun
526
00:34:19,367 --> 00:34:20,920
and Einstein would be wrong.
527
00:34:22,439 --> 00:34:23,716
Fantastic sight of the moon.
528
00:34:27,203 --> 00:34:29,688
USTINOV: The moon
looked splendid.
529
00:34:29,722 --> 00:34:34,348
No amount of scrutiny
by science can efface
its terrible beauty.
530
00:34:37,282 --> 00:34:39,398
You probably want it back now,
don't you, Robert?
531
00:34:39,422 --> 00:34:41,389
Yes.Yes.
532
00:34:42,114 --> 00:34:43,426
Very wise.
533
00:34:45,600 --> 00:34:49,397
To reflect the laser
pulses from the moon,
534
00:34:49,432 --> 00:34:51,296
the Apollo astronauts
535
00:34:51,330 --> 00:34:56,542
set down a series of corner
cubes on the surface
at various locations.
536
00:34:57,957 --> 00:35:02,628
Exactly like the cubed corner
I have here in my hand.
537
00:35:02,652 --> 00:35:05,665
Take a look at it,
you look in at this face,
538
00:35:05,689 --> 00:35:10,763
and you'll see that no matter
what direction the light
enters the corner cube,
539
00:35:10,798 --> 00:35:13,156
it has he remarkable property
540
00:35:13,180 --> 00:35:18,116
of coming out again in
exactly the same path, but
in the opposite direction.
541
00:35:19,462 --> 00:35:20,991
The Soviet Union
542
00:35:21,015 --> 00:35:23,949
landed two Lunar HUD
vehicles on the surface
543
00:35:23,983 --> 00:35:27,918
of the moon and each of them
carried an array of corner
544
00:35:27,953 --> 00:35:30,473
reflectors that were
built by the French.
545
00:35:30,507 --> 00:35:33,683
And tonight we're going to
try and get echoes back
546
00:35:33,752 --> 00:35:35,857
from one of these
Lunar HUD vehicles.
547
00:35:35,926 --> 00:35:38,860
Lunar HUD 21, which you can see
548
00:35:38,929 --> 00:35:41,622
in the upper right hand
corner of the moon,
over there.
549
00:35:41,656 --> 00:35:42,726
USTINOV: Oh yes.
550
00:35:43,796 --> 00:35:46,937
Eric Silverberg
took up the story.
551
00:35:46,972 --> 00:35:49,768
SILVERBERG: We fired
the laser every three seconds
552
00:35:49,802 --> 00:35:52,805
which produces an
extremely intense pulse of
553
00:35:52,840 --> 00:35:57,845
light that starts at the
far end of the room and
then expands
554
00:35:57,879 --> 00:36:01,297
up through this tube
hitting two reflections
555
00:36:01,331 --> 00:36:05,208
and then more until it
fills the entire mirror,
556
00:36:05,232 --> 00:36:08,787
107-inch mirror, which
gives us a very parallel
beam of light
557
00:36:08,821 --> 00:36:10,996
to send up to the moon.Hmm.
558
00:36:11,030 --> 00:36:16,864
We typically fire from
300 to 400 shots in
each 45 minute period.
559
00:36:16,898 --> 00:36:20,799
Since the laser pulse
is about three feet long,
560
00:36:20,833 --> 00:36:24,848
going up to the moon we can
very accurately time
how long it takes
561
00:36:24,872 --> 00:36:27,323
to get there and back.
562
00:36:27,357 --> 00:36:30,912
We always have to station
an aircraft observer outside
563
00:36:30,981 --> 00:36:34,640
the dome to keep track
of any possible nearby
aircraft because of the
564
00:36:34,675 --> 00:36:36,194
intensity of the beam.
565
00:36:38,713 --> 00:36:41,199
We're going to start ranging
on the reflector now
566
00:36:41,233 --> 00:36:47,274
and Robert will
start firing at
the Soviet, uh, site.
567
00:36:49,137 --> 00:36:50,760
His job is the most demanding
568
00:36:50,829 --> 00:36:54,222
because he has to
point the telescope
569
00:36:54,246 --> 00:36:56,214
with an accuracy which is
570
00:36:56,248 --> 00:36:57,836
equivalent to trying
to hit a penny
571
00:36:57,870 --> 00:37:00,563
at a distance of perhaps a mile.
572
00:37:01,564 --> 00:37:03,600
And we help him out
as much as we can
573
00:37:03,669 --> 00:37:07,535
by putting a small
red flash on the image
of the moon in order
574
00:37:07,570 --> 00:37:11,367
to, uh, show him precisely
where the beam is pointed.
575
00:37:13,231 --> 00:37:15,750
In really good conditions
we can get a return
576
00:37:15,785 --> 00:37:21,239
back on the teletype
perhaps every fifth or
every tenth laser shot.
577
00:37:21,273 --> 00:37:24,114
And when it happens
they ring a bell
578
00:37:24,138 --> 00:37:28,739
so that Robert knows precisely
whether or not he's located
at the right position.
579
00:37:28,763 --> 00:37:30,109
[BELL RINGING]
580
00:37:33,112 --> 00:37:36,091
But even with such precise
measurements, it's not easy
581
00:37:36,115 --> 00:37:38,428
to calculate the moon's orbit
582
00:37:38,463 --> 00:37:42,432
because of the myriad
of small effects that
influence its motion.
583
00:37:44,710 --> 00:37:48,335
My colleagues and I use the
measurements made here at
584
00:37:48,404 --> 00:37:52,235
McDonald to actually compute
the moon's orbit to very high
585
00:37:52,270 --> 00:37:57,516
accuracy and found
it to agree very well
with Einstein's claim.
586
00:37:58,483 --> 00:38:00,795
So Einstein's theory has again
587
00:38:00,830 --> 00:38:05,144
withstood another stringent
test and rival theories
588
00:38:05,179 --> 00:38:08,631
are put under much greater
constraints if they're
going to be in
589
00:38:08,665 --> 00:38:12,635
accord with the
behavior of nature.Fantastic.
590
00:38:13,221 --> 00:38:14,361
[BELL RINGING]
591
00:38:17,156 --> 00:38:21,644
USTINOV: I left them
contentedly ringing the
bell for Einstein while
592
00:38:21,678 --> 00:38:25,958
tending a half-baked bun
of comprehension in my brain.
593
00:38:25,993 --> 00:38:29,203
I'd pictured the moon
faithfully circling in
the warped space
594
00:38:29,272 --> 00:38:34,312
around the earth and the
sun's gravity toying with
our own great planet.
595
00:38:40,663 --> 00:38:42,503
WHEELER: Einstein
wouldn't be happy
596
00:38:42,527 --> 00:38:46,703
if we didn't tell you his
story in the simplest words.
597
00:38:46,772 --> 00:38:49,706
Space tells matter how to move
598
00:38:49,775 --> 00:38:53,296
and matter tells
space how to curve.
599
00:38:57,990 --> 00:39:01,718
USTINOV: Warped space didn't
trouble me too deeply.
I remembered how easily
600
00:39:01,787 --> 00:39:05,791
any exercise in straight line
geometry can be botched.
601
00:39:05,826 --> 00:39:09,485
If the young Ustinov could
bend the world...
602
00:39:09,519 --> 00:39:11,210
Why not Einstein?
603
00:39:13,351 --> 00:39:17,665
But to step onto
the quicksands of
Einsteinian time,
604
00:39:17,700 --> 00:39:20,358
er, that was uncanny.
605
00:39:22,221 --> 00:39:26,364
Unsuspectingly, I watched
next morning as a visitor,
John Engelbrecht,
606
00:39:26,398 --> 00:39:27,779
measured the speed of light.
607
00:39:28,918 --> 00:39:31,472
I'm generating the light pulse
608
00:39:31,507 --> 00:39:35,131
with a sparker which
I'm going to turn on here.
609
00:39:35,165 --> 00:39:36,581
[SPARKING]
610
00:39:36,650 --> 00:39:40,067
And that creates sparks,
essentially, short beams
of light
611
00:39:40,101 --> 00:39:41,551
that travel across
to the other dome
612
00:39:42,241 --> 00:39:43,553
where we have the mirror
613
00:39:43,588 --> 00:39:47,212
and the mirror reflects the
beam of light into this
614
00:39:47,246 --> 00:39:51,434
telescope right here, where we
have a photo-multiplier tube
615
00:39:51,458 --> 00:39:56,186
to pick up the light signal
so that we can look at it
616
00:39:56,221 --> 00:39:57,705
on the oscilloscope right here.
617
00:39:58,430 --> 00:40:00,915
We measure the time interval
618
00:40:01,847 --> 00:40:04,125
by measuring the distance
619
00:40:04,194 --> 00:40:09,752
between the two blips on the
oscilloscope where distance
across the screen is time.
620
00:40:09,786 --> 00:40:12,375
Looks like about
450 nanoseconds?
621
00:40:12,410 --> 00:40:15,689
And the round-trip distance
is 134 meters.
622
00:40:15,723 --> 00:40:16,759
Yes.
623
00:40:18,450 --> 00:40:19,865
Well it's not bad.
624
00:40:19,900 --> 00:40:23,524
You've determined the
speed of light this
morning to be about
625
00:40:23,559 --> 00:40:27,908
298 million meters per second.
626
00:40:27,942 --> 00:40:30,669
An accuracy of
about, oh about, uh,
627
00:40:31,429 --> 00:40:34,501
oh, about, uh, one percent.
628
00:40:34,570 --> 00:40:39,954
Um, the speed of light is in
fact, Peter, known to, uh,
great accuracy.
629
00:40:39,989 --> 00:40:42,957
It's one of the most
precisely known numbers
in all of physics.
630
00:40:42,992 --> 00:40:46,236
The national Bureau of
Standards in the United States
631
00:40:46,271 --> 00:40:52,933
uh, has a figure of
about 299,792,457.4
meters per second.
632
00:40:56,661 --> 00:40:57,800
USTINOV: Point four?
633
00:40:57,834 --> 00:41:01,158
Well, the National Physical
Laboratory in London
634
00:41:01,182 --> 00:41:03,150
er, perhaps would disagree
with the last figure.
635
00:41:03,219 --> 00:41:05,324
Ah yes, I thought so.
636
00:41:06,912 --> 00:41:09,812
BRECHER: Einstein
was emphatic that
a blast of light is
637
00:41:09,846 --> 00:41:14,472
always a constant no matter
what the motion of the source
or the motion of the observer.
638
00:41:14,506 --> 00:41:18,648
I've checked this, in fact,
using not light but x-rays
639
00:41:18,683 --> 00:41:21,099
which are a form of light
but at very high energies.
640
00:41:26,725 --> 00:41:30,325
BRECHER: In 1970, a satellite
was launched off the coast
of Kenya for the purpose
641
00:41:30,349 --> 00:41:32,835
of doing x-ray astronomy.
642
00:41:34,837 --> 00:41:35,976
It was called Uhuru.
643
00:41:37,564 --> 00:41:41,947
It discovered and
began observing a
peculiar class of star.
644
00:41:41,982 --> 00:41:45,202
An x-ray binary pulsar gives
off regular bursts of x-rays
645
00:41:45,226 --> 00:41:47,850
while orbiting at high
speed around another star.
646
00:41:48,954 --> 00:41:51,198
Now suppose that
Einstein were wrong
647
00:41:51,232 --> 00:41:53,303
and that x-rays go faster
if they were launched
648
00:41:53,338 --> 00:41:56,306
when the pulsar is moving
towards the earth.
649
00:41:56,341 --> 00:41:59,206
Then x-rays from that part
of the orbit could overtake
650
00:41:59,240 --> 00:42:02,243
x-rays that are coming from
the other part of the orbit,
651
00:42:02,312 --> 00:42:05,350
making a simple picture
quite complicated.
652
00:42:05,384 --> 00:42:09,975
For example, you could see
the pulsar coming and going
at the same time.
653
00:42:14,911 --> 00:42:18,719
Peter, from my
friend Ethan Schreier
654
00:42:18,743 --> 00:42:22,067
at the Smithsonian
Astrophysical Observatory,
655
00:42:22,091 --> 00:42:24,093
who worked on the
Uhuru satellite,
656
00:42:24,162 --> 00:42:27,475
I got the following
tracing of x-ray pulses
657
00:42:27,510 --> 00:42:31,445
coming from the
x-ray pulsar Centaurus X-3.
658
00:42:31,514 --> 00:42:33,906
And as you can see by
looking at these pulses,
659
00:42:33,930 --> 00:42:36,208
they're absolutely regular.
660
00:42:36,243 --> 00:42:39,867
Each pulse comes along
at a specific time interval
661
00:42:39,902 --> 00:42:44,216
and there are no spurious
ghost pulses lying in between
the pulses that we see here.
662
00:42:44,251 --> 00:42:46,436
This is direct proof that
the speed of light
663
00:42:46,460 --> 00:42:49,256
is indeed independent of the
velocity of the source.
664
00:42:49,290 --> 00:42:51,268
I looked at three
separate sources.
665
00:42:51,292 --> 00:42:55,642
The most distant one, lying
in the small Magellanic Cloud,
666
00:42:55,711 --> 00:42:59,369
the light took 200,000 years
to arrive at the earth
667
00:42:59,404 --> 00:43:00,681
from that source.
668
00:43:00,716 --> 00:43:03,891
And in all that time,
the pulses emitted
669
00:43:03,926 --> 00:43:07,654
when the pulsar came
towards us, never
670
00:43:07,723 --> 00:43:10,864
overran those that were
emitted when it went away.
671
00:43:10,898 --> 00:43:15,903
By more than a factor of
perhaps a part in a billion.
672
00:43:15,938 --> 00:43:20,435
To put it in earthly
terms, that would be
about the speed of a
673
00:43:20,459 --> 00:43:22,299
turtle moving along the ground.
674
00:43:22,323 --> 00:43:24,015
USTINOV: That's a
very earthly term.
675
00:43:28,398 --> 00:43:32,137
USTINOV: In deference
to this evident obsession
of Einstein's,
676
00:43:32,161 --> 00:43:36,406
I accepted that in cosmic
space the speed of x-rays
677
00:43:36,441 --> 00:43:41,802
or visible light or
radio waves, never varies.
678
00:43:41,826 --> 00:43:45,692
But, dear me, how promptly
that golden rule was broken.
679
00:43:47,970 --> 00:43:50,455
SHAPIRO: If we send
radio pulses
680
00:43:50,489 --> 00:43:52,975
to another planet like
Mercury or Venus
681
00:43:53,009 --> 00:43:56,116
when they're on the other
side of the sun from earth,
682
00:43:56,150 --> 00:44:01,190
they can appear to be slowed
down by the direct effect
of the sun's gravity
683
00:44:01,259 --> 00:44:03,986
on the waves as they
pass near the sun.
684
00:44:05,608 --> 00:44:08,853
USTINOV: It looks,
from where we are,
as if the sun's gravity
685
00:44:08,887 --> 00:44:12,960
acts very like a lens, bending
the light and slowing it down.
686
00:44:15,169 --> 00:44:17,171
SHAPIRO: About
fifteen years ago
687
00:44:17,206 --> 00:44:20,703
it occurred to me
that this increase
in the travel time
688
00:44:20,727 --> 00:44:25,490
was a direct consequence
of Einstein's general
theory of relativity.
689
00:44:26,456 --> 00:44:28,493
In those days of increasing
690
00:44:28,527 --> 00:44:31,151
science budgets and
low rate of inflation
691
00:44:31,185 --> 00:44:33,222
it took less than two years
692
00:44:33,291 --> 00:44:36,984
to convert that idea into
a very sophisticated radar
693
00:44:37,019 --> 00:44:41,023
system which we installed
on the Haystack telescope
694
00:44:41,057 --> 00:44:44,543
to make these measurements
on Mercury and Venus.
695
00:44:46,062 --> 00:44:48,858
Now the actual predicted
effect is very small,
696
00:44:48,893 --> 00:44:53,829
it's only 200
millionths of a second out
of a total round-trip time
697
00:44:53,863 --> 00:44:56,866
of about 1,500 seconds
or approximately
698
00:44:56,901 --> 00:44:59,041
one part in 10 million.
699
00:44:59,075 --> 00:45:01,595
And we were able to
measure it with an accuracy
700
00:45:01,664 --> 00:45:06,231
of approximately five or
ten percent with this
radar experiments.
701
00:45:06,255 --> 00:45:08,119
Now, if we could turn to Mars...
702
00:45:08,913 --> 00:45:10,708
[ELECTRONIC WHIRRING]
703
00:45:11,916 --> 00:45:14,539
CALDER: You can't expect
to make that image
of Mars just now
704
00:45:14,573 --> 00:45:17,380
because it's right
on the far side
of the sun
705
00:45:17,404 --> 00:45:20,200
and it's close to the horizon.
706
00:45:20,234 --> 00:45:22,892
But, uh, maybe
we'll get an impression.
707
00:45:24,411 --> 00:45:28,518
SHAPIRO: Mars is now
very near the far side
of the sun
708
00:45:28,553 --> 00:45:30,037
as we view it from Earth
709
00:45:30,072 --> 00:45:33,696
and is in a good position
to see this effect.
710
00:45:33,731 --> 00:45:37,355
And in fact, the last time
Mars was in this position,
711
00:45:37,389 --> 00:45:40,876
we used radio waves
sent to the Viking spacecraft
712
00:45:40,910 --> 00:45:43,268
which we landed on
the surface of Mars
713
00:45:43,292 --> 00:45:47,928
to measure
this predicted slow-down
much more accurately.
714
00:45:47,952 --> 00:45:50,437
And with such measurements
we're able to verify
715
00:45:50,471 --> 00:45:54,451
the predictions of
general relativity on
regard to the slow-down
716
00:45:54,475 --> 00:45:58,617
to an accuracy of about
one-tenth of one percent.
717
00:45:58,652 --> 00:46:02,690
Okay, you say
light slows down
near the sun.
718
00:46:02,725 --> 00:46:04,451
But Ken Brecher told us just now
719
00:46:04,485 --> 00:46:08,455
that light seems
always to go at
the same speed.
720
00:46:08,489 --> 00:46:10,422
I think, Peter,
that as a theorist,
721
00:46:10,457 --> 00:46:14,668
Roger Penrose here
might resolve that
contradiction for us.
722
00:46:14,737 --> 00:46:17,395
Yes, well, you see,
it really depends where
the measurement is done.
723
00:46:17,429 --> 00:46:19,949
If you measure
the speed of light
724
00:46:19,984 --> 00:46:22,434
as it appears at
the surface of the sun
725
00:46:22,469 --> 00:46:26,093
from here
then it would seem
as though it slows down.
726
00:46:26,128 --> 00:46:30,270
It would seem as though
the sun was surrounded
by some sort of lens
727
00:46:30,304 --> 00:46:33,273
that should not only
slow the light but
also bend the light.
728
00:46:33,307 --> 00:46:36,448
But if you did
the measurement at
the surface of the sun
729
00:46:36,483 --> 00:46:38,841
then you would get
the same answer
for the speed of light
730
00:46:38,865 --> 00:46:41,799
as you get from
the speed of light at
the surface of the Earth.
731
00:46:43,110 --> 00:46:45,112
USTINOV: We had come
to the nub.
732
00:46:45,147 --> 00:46:49,668
To keep his blessed
speed of light always
reading the same,
733
00:46:49,703 --> 00:46:56,158
Einstein decided that
time itself must slow down
near a massive object.
734
00:46:58,712 --> 00:47:03,130
So gravity has
the apparent effect of
reducing the speed of light
735
00:47:03,165 --> 00:47:05,868
and slowing down time.
736
00:47:05,892 --> 00:47:09,688
So if you imagined
the extreme situation
of a black hole
737
00:47:09,723 --> 00:47:14,314
then light would be reduced
to zero speed apparently
738
00:47:14,348 --> 00:47:19,698
and time would apparently
have been stopped
completely at the surface.
739
00:47:19,767 --> 00:47:21,366
Apparently?
740
00:47:21,390 --> 00:47:25,152
Well, I feel awfully guilty
asking this because
I'm opening,
741
00:47:25,187 --> 00:47:27,199
as they say here,
a new can of peas,
742
00:47:27,223 --> 00:47:30,030
but we've heard so much
about black holes.
743
00:47:30,054 --> 00:47:32,988
What is a black hole apparently?
744
00:47:33,022 --> 00:47:35,714
Yes, well, according
to Einstein's theory,
745
00:47:35,749 --> 00:47:39,787
if you have the final fate
of a very massive star,
746
00:47:39,822 --> 00:47:42,583
would be an object
so concentrated
747
00:47:42,652 --> 00:47:45,690
that light itself
couldn't escape from it.
748
00:47:45,724 --> 00:47:50,395
The object collapses inwards
and, uh, signals,
749
00:47:50,419 --> 00:47:53,491
light, any other kind
of signal, any object,
750
00:47:53,525 --> 00:47:55,148
cannot escape from this region
751
00:47:55,182 --> 00:47:58,082
into which the star
would collapse.
752
00:47:58,151 --> 00:48:01,533
The black hole that results
from the collapse of a star
753
00:48:01,568 --> 00:48:03,363
several times
the mass of the sun,
754
00:48:03,397 --> 00:48:07,239
would be an object
several miles in diameter.
755
00:48:07,263 --> 00:48:09,576
But if you, say,
imagined the Earth
756
00:48:09,610 --> 00:48:12,762
compressed right down
until it became a black hole,
757
00:48:12,786 --> 00:48:17,584
the dimension would be
a bit less than an inch
or something like that.
758
00:48:17,618 --> 00:48:19,769
USTINOV: That's the Earth? The
Earth would have to be compressed
759
00:48:19,793 --> 00:48:22,071
into that size to be
a black hole. USTINOV: I see.
760
00:48:22,106 --> 00:48:23,428
USTINOV: So,
you shouldn't be candid.
761
00:48:23,452 --> 00:48:25,316
Don't worry. [CHUCKLES]USTINOV: I see.
762
00:48:27,456 --> 00:48:29,744
PENROSE: Light at
the surface of a black hole
trying to escape
763
00:48:29,768 --> 00:48:31,287
would hover there forever.
764
00:48:31,356 --> 00:48:34,773
And judged by us,
looking from a safe distance,
765
00:48:34,842 --> 00:48:36,430
time there appears to stop.
766
00:48:42,954 --> 00:48:46,130
You'd wait forever for
the next tick of the clock.
767
00:48:46,199 --> 00:48:48,477
A short distance away
from the black hole,
768
00:48:48,546 --> 00:48:52,170
time does seem to pass
but rather slowly
by our reckoning.
769
00:48:54,172 --> 00:48:56,899
You can think of
the black hole to be
surrounded by shells
770
00:48:56,934 --> 00:48:59,626
in which time runs
progressively faster.
771
00:49:04,424 --> 00:49:07,461
That's what happens
in the immediate vicinity
of a black hole.
772
00:49:07,496 --> 00:49:10,292
But the effects on time extend
for thousands of miles
773
00:49:10,326 --> 00:49:14,261
with time getting
gradually closer to what
we regard as the normal rate.
774
00:49:18,783 --> 00:49:20,312
If you imagine
that little black hole
775
00:49:20,336 --> 00:49:21,855
with the same mass as the Earth
776
00:49:21,924 --> 00:49:24,627
and surround it by
a sphere representing
the Earth's surface,
777
00:49:24,651 --> 00:49:26,146
where we live,
778
00:49:26,170 --> 00:49:29,552
our clocks run at
the appropriate rate.
779
00:49:31,313 --> 00:49:34,454
There isn't really
a black hole at
the center of the Earth
780
00:49:34,488 --> 00:49:36,456
but time at the Earth's surface
781
00:49:36,490 --> 00:49:39,252
is so little
just as if they were.
782
00:49:39,286 --> 00:49:42,531
Compared with
the very gradually
increasing rates of time
783
00:49:42,600 --> 00:49:45,223
way out in space high above
the Earth's surface.
784
00:49:56,372 --> 00:50:00,376
"The observer will
interpret what he sees
785
00:50:00,445 --> 00:50:02,482
"as showing that one clock
786
00:50:02,516 --> 00:50:05,830
"really goes more slowly
than another clock.
787
00:50:05,864 --> 00:50:09,696
"So, he will be obliged to
define time in such a way
788
00:50:09,730 --> 00:50:14,632
"that the rate of a clock
depends on where
the clock may be."
789
00:50:17,393 --> 00:50:23,365
Peter, the interesting thing
about general relativity
is that my clock,
790
00:50:23,399 --> 00:50:26,161
whether I'm sitting here
on the surface of the Earth,
791
00:50:26,195 --> 00:50:28,335
whether I'm orbiting
around a black hole,
792
00:50:28,370 --> 00:50:31,994
will appear to me
always to be running
at the same rate.
793
00:50:32,029 --> 00:50:37,965
The gravitational effects
don't change the actual
clockwork mechanism,
794
00:50:38,000 --> 00:50:39,726
and don't affect it in any way.
795
00:50:39,760 --> 00:50:41,935
Nonetheless, from
your point of view,
796
00:50:42,004 --> 00:50:44,731
you might see my clock
running at a different rate
797
00:50:44,765 --> 00:50:48,597
and we would appear
to have time running
at different rates.
798
00:50:48,666 --> 00:50:51,196
We could correct for this,
and general relativity
in fact tells us
799
00:50:51,220 --> 00:50:52,980
exactly how to do that,
800
00:50:53,015 --> 00:50:57,364
um, but the, uh,
the clocks themselves
801
00:50:57,399 --> 00:51:01,265
are in fact not disturbed
by the gravitational field.
802
00:51:01,334 --> 00:51:03,001
Yeah. I... I don't quite
understand one thing
803
00:51:03,025 --> 00:51:05,762
because obviously
we are our own
terms of reference
804
00:51:05,786 --> 00:51:08,996
and therefore our clocks
are our own terms
of reference,
805
00:51:09,031 --> 00:51:10,688
they become part of us.
806
00:51:10,722 --> 00:51:14,899
If I take an airplane,
as we all do
and fly very high,
807
00:51:14,933 --> 00:51:17,971
is there what is shown
on the clock face
808
00:51:18,040 --> 00:51:21,112
affected by the fact
that I have flown high
809
00:51:21,181 --> 00:51:23,287
or not, by the time I arrive?
810
00:51:23,356 --> 00:51:25,392
Yes, it is in fact affected
811
00:51:25,427 --> 00:51:29,258
and when you come back
it will read differently
from the identical clock
812
00:51:29,293 --> 00:51:32,789
which you left behind
which didn't take part
in the airplane ride.
813
00:51:32,813 --> 00:51:36,793
But although the clock reading
is different when you come
back on the ground,
814
00:51:36,817 --> 00:51:38,543
the clock,
once it's back
on the ground
815
00:51:38,578 --> 00:51:42,961
will continue to run at
the same rate it used to
run on the ground.
816
00:51:42,996 --> 00:51:45,964
So that the difference
in reading will then
remain constant
817
00:51:46,033 --> 00:51:47,518
as time goes on.
818
00:51:47,587 --> 00:51:51,591
The important point
is that this effect is
not a psychological effect.
819
00:51:51,625 --> 00:51:54,732
It's a genuine,
measurable, physical effect.
820
00:51:54,766 --> 00:51:58,736
In the last decade or so,
extraordinarily accurate
atomic clocks
821
00:51:58,770 --> 00:52:00,979
have been made
which are sensitive enough
822
00:52:01,048 --> 00:52:03,475
to see these very small effects.
823
00:52:03,499 --> 00:52:05,501
Such that, for example,
the difference between
824
00:52:05,570 --> 00:52:07,607
the rate of a clock
running on the ground
825
00:52:07,641 --> 00:52:10,437
and one running
on the second story
of a building
826
00:52:10,472 --> 00:52:14,441
could be observed and
measured very accurately.
827
00:52:14,476 --> 00:52:16,823
Oh, so Big Ben's been
wrong all the time
828
00:52:16,857 --> 00:52:18,618
because it's at
about the eighth floor?
829
00:52:18,652 --> 00:52:21,448
[LAUGHS] I see. Right, it's gaining
relative to your clocks.
830
00:52:21,483 --> 00:52:24,934
USTINOV: My common sense
was outraged, of course.
831
00:52:24,969 --> 00:52:27,627
Yet, recent results
have evidently smothered
832
00:52:27,661 --> 00:52:32,494
all expert
and inexpert doubts
about Einsteinian time.
833
00:52:33,943 --> 00:52:37,119
Sidney Drell set the scene.
834
00:52:37,154 --> 00:52:41,710
The atomic clock is
not just an instrument
for scientific laboratories
835
00:52:41,779 --> 00:52:46,863
to run their equipment with
or part of their play
equipment.
836
00:52:46,887 --> 00:52:52,548
In fact, in everyday life
it sets the time
by which we live.
837
00:52:52,617 --> 00:52:56,518
Here, one has
a crystal oscillator
838
00:52:56,552 --> 00:53:00,556
which keeps time
relative to an atomic clock
839
00:53:00,625 --> 00:53:03,397
which signal is
being received here
840
00:53:03,421 --> 00:53:07,908
with due allowance for
the time it takes for light
to bring the signal here.
841
00:53:07,977 --> 00:53:11,188
Here is the time
that it's reading out.
842
00:53:13,466 --> 00:53:15,571
I notice that my own
crystal watch
843
00:53:15,640 --> 00:53:19,541
is two seconds slow
by the time given there.
844
00:53:21,405 --> 00:53:25,581
Well... Mine is
six seconds out.
That's terrible.
845
00:53:25,650 --> 00:53:28,101
Well, this will go
back to the maker.
846
00:53:28,170 --> 00:53:32,381
DRELL: Back in Washington,
there sits the master
atomic clock
847
00:53:32,416 --> 00:53:35,177
against which all
other time is referenced
848
00:53:35,212 --> 00:53:37,179
for an international
time standard.
849
00:53:38,387 --> 00:53:41,401
The atomic clocks
keep time to an accuracy
850
00:53:41,425 --> 00:53:44,945
which approaches one second
out of a million years.
851
00:53:45,014 --> 00:53:46,809
That is how far they have come.
852
00:53:48,949 --> 00:53:52,021
To understand the atomic clock
853
00:53:52,056 --> 00:53:56,416
we have to now enter
into the theory of atoms.
854
00:53:56,440 --> 00:53:58,442
And this is another theory,
855
00:53:58,476 --> 00:54:03,895
the theory of, uh,
how light is emitted
and absorbed by atoms
856
00:54:03,930 --> 00:54:09,291
and how light propagates
with very sharply
defined frequencies.
857
00:54:09,315 --> 00:54:12,432
There's another, uh,
theory to which Einstein made
858
00:54:12,456 --> 00:54:15,390
very enormous contributions.
859
00:54:15,424 --> 00:54:18,185
Sometimes we think
of the year 1905,
860
00:54:18,220 --> 00:54:20,464
when Einstein was 26 years old,
861
00:54:20,533 --> 00:54:22,466
as one of the miracle years
of the world.
862
00:54:22,500 --> 00:54:26,608
Because in that year
when he was giving us
special relativity, Peter,
863
00:54:26,642 --> 00:54:29,621
he was also giving us
the theory of light
864
00:54:29,645 --> 00:54:33,718
occurring in discrete packages
and with precise frequencies.
865
00:54:33,753 --> 00:54:37,584
It was, in fact,
with this work
that in 1921,
866
00:54:37,619 --> 00:54:39,793
he received the Nobel Prize,
867
00:54:39,828 --> 00:54:43,141
when the relativity theory
was still viewed as
too mathematical,
868
00:54:43,176 --> 00:54:48,423
too controversial
and not really of
practical importance.
869
00:54:48,457 --> 00:54:50,228
CALDER: This side of
Washington, they keep
the clocks
870
00:54:50,252 --> 00:54:51,988
that directly answer
your question, Peter,
871
00:54:52,012 --> 00:54:55,509
about how time passes
in an aircraft.
872
00:54:55,533 --> 00:54:59,296
Karel Ally of
the University of Maryland,
and his colleagues,
873
00:54:59,330 --> 00:55:03,507
put one set of atomic clocks
aboard a US Navy airplane.
874
00:55:03,576 --> 00:55:05,888
And this was starting in 1975.
875
00:55:07,683 --> 00:55:09,316
And you remember, on the moon,
876
00:55:09,340 --> 00:55:11,860
those man-made
corner reflectors,
877
00:55:11,929 --> 00:55:14,345
well, the aircraft
carried one of them
878
00:55:14,414 --> 00:55:17,324
to throw back
yet more laser pulses.
879
00:55:17,348 --> 00:55:20,362
Providing a link to
another set of clocks
880
00:55:20,386 --> 00:55:23,354
kept in a cabin
on the ground for comparison.
881
00:55:23,423 --> 00:55:25,529
USTINOV: The same types
of atomic clock?
882
00:55:25,598 --> 00:55:27,841
CALDER: Yes,
they're twin brothers
in effect.
883
00:55:34,192 --> 00:55:36,022
The prediction
of general relativity
884
00:55:36,056 --> 00:55:38,690
is that as you get
higher above the ground,
885
00:55:38,714 --> 00:55:40,854
the grip of gravity
on time weakens
886
00:55:40,889 --> 00:55:43,340
and your clock
should run a little faster.
887
00:55:44,479 --> 00:55:47,033
The laser flashes
coming from base
888
00:55:47,067 --> 00:55:50,485
serve to check the time
recorded in the air
889
00:55:50,519 --> 00:55:53,049
against the readings
of the clocks on the ground
890
00:55:53,073 --> 00:55:57,146
while the aircraft flew around
and around Chesapeake Bay.
891
00:55:59,079 --> 00:56:01,323
The ground radar
kept track of it.
892
00:56:01,358 --> 00:56:04,716
The aircraft's speed,
by the way, also had
a very small effect on time
893
00:56:04,740 --> 00:56:07,364
by a quite different
prediction of relativity
894
00:56:07,398 --> 00:56:10,539
but the experimenters
took that accurately
into account.
895
00:56:10,574 --> 00:56:13,069
USTINOV: [LAUGHS] Yes,
I'm sure they did.
896
00:56:13,093 --> 00:56:17,374
CALDER: The main effect
on time related to
the aircraft's height.
897
00:56:17,995 --> 00:56:20,204
At 35,000 feet,
898
00:56:20,238 --> 00:56:24,346
the airborne clocks gained
about three billionths
of a second every hour,
899
00:56:24,381 --> 00:56:27,418
and each flight lasted
about 15 hours
900
00:56:27,487 --> 00:56:30,076
and five flights like that
accurately confirmed
901
00:56:30,145 --> 00:56:32,561
the effect of gravity on time.
902
00:56:35,357 --> 00:56:39,361
So Einstein's account
of how the world works
triumphs yet again.
903
00:56:42,709 --> 00:56:47,127
USTINOV: "To punish me
for my contempt for authority,
904
00:56:47,196 --> 00:56:51,408
"fate made me
authority myself."
905
00:56:55,239 --> 00:56:57,793
CALDER: And what's true
of atoms and atomic clocks
906
00:56:57,862 --> 00:57:01,279
is also true of atoms
in ordinary objects
like an apple.
907
00:57:01,314 --> 00:57:03,592
And perhaps
we could draw some
of these threads together
908
00:57:03,627 --> 00:57:06,733
by telling, how in a time shell,
909
00:57:06,768 --> 00:57:11,082
starting at the top of a tree
and moving into a time shell
lower down,
910
00:57:11,117 --> 00:57:15,052
an apple manages to accelerate
in the way that's so familiar.
911
00:57:17,123 --> 00:57:20,713
CALDER: It's moving
into shells, very fine shells,
912
00:57:20,747 --> 00:57:23,060
of ever slowing time.
913
00:57:23,094 --> 00:57:25,452
Its atoms are
operating more slowly.
914
00:57:25,476 --> 00:57:28,445
It seems to be
losing internal energy
915
00:57:28,479 --> 00:57:31,137
which has to reappear
in some new form
916
00:57:31,171 --> 00:57:33,805
and the form it takes
is energy of motion.
917
00:57:33,829 --> 00:57:38,178
So the apple is going faster
and faster as it moves down
918
00:57:38,247 --> 00:57:41,837
into slower and
slower zones of time.
919
00:57:41,906 --> 00:57:44,644
Until finally it hits the ground
920
00:57:44,668 --> 00:57:47,740
and that energy of motion
is destroyed.
921
00:57:52,607 --> 00:57:56,990
USTINOV: Well, Nigel,
just two little points
I'd like to clarify
922
00:57:57,025 --> 00:58:00,131
before we all go further
into this adventure.
923
00:58:00,166 --> 00:58:04,353
It seems to me that
the apple has acquired
such a particular status
924
00:58:04,377 --> 00:58:07,518
with Newton, that perhaps
one ought to realize
925
00:58:07,587 --> 00:58:11,384
for uninitiated agriculturalists
926
00:58:11,453 --> 00:58:17,159
that pears and grapes and,
in fact, people are subject
to the same laws,
927
00:58:17,183 --> 00:58:19,772
that pears are not exempt.
928
00:58:19,806 --> 00:58:21,636
Exempt from
the action of gravity.
929
00:58:21,670 --> 00:58:23,810
Well, uh,
certainly not, because,
930
00:58:23,845 --> 00:58:25,812
especially since Einstein,
931
00:58:25,847 --> 00:58:28,781
the emphasis in present thinking
932
00:58:28,815 --> 00:58:33,164
is that gravity
affects everything
in just the same way.
933
00:58:33,199 --> 00:58:35,132
And in the case of people
934
00:58:35,166 --> 00:58:39,688
our atoms also are affected
in that rate of operation
935
00:58:39,723 --> 00:58:43,002
according to whether
we're living down
in the valley
936
00:58:43,036 --> 00:58:45,349
or up on the mountain.
937
00:58:45,383 --> 00:58:46,663
USTINOV: I found
the propositions
938
00:58:46,695 --> 00:58:49,629
of general relativity
easy to state.
939
00:58:49,664 --> 00:58:53,288
Gravity bends light
and warps space.
940
00:58:55,048 --> 00:59:00,019
Gravity slows down light
and slows down time.
941
00:59:00,053 --> 00:59:04,402
Bewilderingly simple, really,
as their full meaning sank in.
942
00:59:07,405 --> 00:59:10,892
CALDER: You could think,
if you dared, of visiting
a black hole
943
00:59:10,926 --> 00:59:13,204
and hovering there for a while.
944
00:59:13,239 --> 00:59:18,910
And there in
the slow running time shells
close to the black hole,
945
00:59:18,934 --> 00:59:21,696
perhaps only
a few years would pass
946
00:59:21,730 --> 00:59:25,078
while hundreds of years
were passing on Earth.
947
00:59:25,113 --> 00:59:26,942
Maybe you'd like
to imagine yourself
948
00:59:27,011 --> 00:59:30,152
as twin brothers
testing this theory.
949
00:59:30,187 --> 00:59:32,096
USTINOV: Hmm.
950
00:59:32,120 --> 00:59:36,262
"The adventurous one
is my twin brother, Peter,
951
00:59:37,366 --> 00:59:41,923
"and my cautious one
is... [CHUCKLES] Albert."
952
00:59:43,580 --> 00:59:48,930
And Peter
wanted very badly to
investigate this black hole.
953
00:59:48,999 --> 00:59:50,770
[WHOOPS]
954
00:59:50,794 --> 00:59:53,520
USTINOV: He's always
been reckless. You coming?
955
00:59:53,555 --> 00:59:55,522
[LAUGHING] You silly boy.
[SNIFFLES]
956
00:59:56,075 --> 00:59:57,076
Ah!
957
00:59:57,628 --> 00:59:58,628
[CHUCKLES]
958
00:59:59,388 --> 01:00:01,459
It's going to be great up there!
959
01:00:02,702 --> 01:00:03,876
That's certain.
960
01:00:06,292 --> 01:00:09,398
How about that?
961
01:00:09,433 --> 01:00:13,886
USTINOV: That's the last
we've seen of Peter on
this Earth anyway.
962
01:00:13,920 --> 01:00:16,302
Would I dare make
the imaginary journey
963
01:00:16,336 --> 01:00:18,960
to the black hole now proposed?
964
01:00:19,788 --> 01:00:22,480
Well... Why not?
965
01:00:29,833 --> 01:00:31,386
[CHUCKLING] Goodbye!
966
01:00:32,421 --> 01:00:33,733
Goodbye.
967
01:00:34,976 --> 01:00:35,976
[ELECTRONIC BEEP]
968
01:00:37,841 --> 01:00:39,912
Oh, do take care.
969
01:00:47,367 --> 01:00:50,854
USTINOV: I shook the dust
of the 20th century
from my feet
970
01:00:50,923 --> 01:00:55,099
as my imagination bounded
towards the black hole.
971
01:01:04,661 --> 01:01:10,114
I'm just nosing in
towards the black hole now.
972
01:01:10,149 --> 01:01:11,149
[ELECTRONIC BEEP]
973
01:01:13,462 --> 01:01:19,986
[DISTORTED SPEECH]
I'm just nosing in towards
the black hole now.
974
01:01:24,957 --> 01:01:26,199
Well...
975
01:01:27,338 --> 01:01:29,040
At least that black hole
has slowed down
976
01:01:29,064 --> 01:01:34,380
the hectic pace of his life
but I hope to God
he takes care.
977
01:01:39,040 --> 01:01:43,147
USTINOV: The rate of time
seemed entirely normal to me,
but on the Earth
978
01:01:43,182 --> 01:01:46,392
it was evidently racing along.
979
01:01:49,775 --> 01:01:55,919
BRECHER: The gravitational
effects don't change the
actual clockwork mechanism.
980
01:01:55,988 --> 01:01:58,093
Nonetheless,
from your point of view,
981
01:01:58,162 --> 01:02:00,855
you might see my clock
running at a different rate.
982
01:02:04,168 --> 01:02:06,377
USTINOV: Pictures from
the Earth showed the days
983
01:02:06,412 --> 01:02:08,414
passing in a matter of minutes.
984
01:02:17,112 --> 01:02:18,527
[TAPE FAST FORWARDING]
985
01:02:24,602 --> 01:02:30,367
I saw who won
the Grand National
in 1990 but I shan't tell.
986
01:02:34,820 --> 01:02:38,893
It was hard to make out
what Albert was saying
in mission control.
987
01:02:38,927 --> 01:02:40,594
[TAPE FAST FORWARDING]
988
01:02:40,618 --> 01:02:45,347
[TAPE FAST FORWARDING]
989
01:02:49,558 --> 01:02:52,423
Uh, anyway,
your will is in spirit
990
01:02:52,458 --> 01:02:56,220
and we'll be able
to celebrate any moment now.
991
01:02:56,255 --> 01:02:57,566
[CLOCK GONGS]Yes!
992
01:02:58,119 --> 01:03:00,569
A happy new century!
993
01:03:00,604 --> 01:03:02,192
[STUTTERS]
Happy day... Yeah.
994
01:03:02,226 --> 01:03:03,227
[CHUCKLES]
995
01:03:05,298 --> 01:03:08,474
[CLOCK GONGS][LAUGHING]
Missed the bloody bottle!
996
01:03:09,751 --> 01:03:13,282
I see, you look very spry,
yes, you do.
997
01:03:13,306 --> 01:03:14,791
[TAPE FAST FORWARDING]
998
01:03:16,137 --> 01:03:18,587
Twenty-first century?
999
01:03:18,622 --> 01:03:23,499
We're still 20 years off
by my reckoning.
[CHUCKLES]
1000
01:03:23,523 --> 01:03:27,355
USTINOV: As years passed
on Earth and only months
on my spaceship,
1001
01:03:27,424 --> 01:03:30,161
my greatest concern
was for Albert.
1002
01:03:30,185 --> 01:03:33,326
My twin brother was aging
before my eyes.
1003
01:03:35,328 --> 01:03:38,262
As for me, I was only
a few months older.
1004
01:03:40,609 --> 01:03:47,340
[VOICE TREMBLING] Well,
it would appear that
Mr. Einstein was right.
1005
01:03:47,409 --> 01:03:48,686
Eh, Peter?
1006
01:03:48,755 --> 01:03:50,412
[SOFT CHUCKLE]
1007
01:03:51,793 --> 01:03:56,625
As you can see,
I'm still trying
to look after you
1008
01:03:56,660 --> 01:03:58,696
in spite of...
1009
01:04:00,698 --> 01:04:01,838
Nurse...
1010
01:04:04,185 --> 01:04:07,360
[TAPE FAST FORWARDING]
1011
01:04:09,742 --> 01:04:13,539
USTINOV: It wasn't long before
the Earth forgot all about me.
1012
01:04:14,367 --> 01:04:16,542
[SIGHS] Time to go home.
1013
01:04:17,439 --> 01:04:18,440
[ELECTRONIC BEEP]
1014
01:04:26,897 --> 01:04:28,219
USTINOV: Before
I could even think
1015
01:04:28,243 --> 01:04:31,729
of playing Rip Van Winkle
in the world of
the 21st century,
1016
01:04:31,764 --> 01:04:35,147
there was one visit
I had to make.
1017
01:04:39,910 --> 01:04:40,910
[ELECTRONIC BEEP]
1018
01:04:43,155 --> 01:04:44,155
[SPACESHIP POWERING DOWN]
1019
01:04:50,472 --> 01:04:51,991
[WIND WHOOSHING]
1020
01:05:04,417 --> 01:05:06,903
Alas, poor Albert.
1021
01:05:09,077 --> 01:05:12,574
Even in imagination,
this time travel
by means of gravity
1022
01:05:12,598 --> 01:05:16,291
seemed a joyless enterprise.
1023
01:05:16,326 --> 01:05:20,744
There was no method
for retracing my steps
through Einsteinian time
1024
01:05:20,778 --> 01:05:23,436
and returning
to the 20th century.
1025
01:05:27,785 --> 01:05:29,718
We've talked about
the warping of space
1026
01:05:29,753 --> 01:05:33,653
and about the effects
of gravity on time,
in space and time.
1027
01:05:33,722 --> 01:05:38,141
But relativists like
to combine the two
into space-time.
1028
01:05:38,210 --> 01:05:41,154
With time as being
the fourth dimension.
1029
01:05:41,178 --> 01:05:45,286
USTINOV: "The
non-mathematician is seized
by a mysterious shuddering
1030
01:05:45,320 --> 01:05:49,566
"when he hears of
four-dimensional things.
1031
01:05:49,600 --> 01:05:54,650
"By a feeling not unlike
that awakened by thoughts
of the occult.
1032
01:05:54,674 --> 01:05:57,988
"And yet, there is no more
commonplace statement
1033
01:05:58,057 --> 01:06:00,853
"than that the world
in which we live
1034
01:06:00,922 --> 01:06:06,662
"is a four-dimensional
space-time continuum."
1035
01:06:06,686 --> 01:06:09,310
Here we are
at a certain place
in Western Texas.
1036
01:06:10,242 --> 01:06:12,658
And the time
is half past eleven.
1037
01:06:13,831 --> 01:06:15,154
Put the two together...
[CLAPS]
1038
01:06:15,178 --> 01:06:19,458
I clap my hands,
that's an event
in space-time.
1039
01:06:19,492 --> 01:06:23,679
Now each of our lives is
a series of such events
strung together
1040
01:06:23,703 --> 01:06:26,844
into a world line in space-time.
1041
01:06:26,879 --> 01:06:30,676
And here we meet together,
our world lines more
or less intersect.
1042
01:06:32,126 --> 01:06:33,966
PENROSE: In order to get
a picture of space-time,
1043
01:06:33,990 --> 01:06:39,064
it's convenient to think
of space as represented as
a two-dimensional flat plate
1044
01:06:39,133 --> 01:06:42,446
and that frees
the third dimension
to represent time.
1045
01:06:48,418 --> 01:06:53,975
Now, let us imagine
an object which is
stationary in our description.
1046
01:06:54,010 --> 01:06:57,772
Then this would be represented
by a vertical straight line.
1047
01:07:01,017 --> 01:07:06,056
An object
which is moving uniformly
but with some velocity,
1048
01:07:06,091 --> 01:07:10,440
would be represented again
by a straight line but
now tilted over.
1049
01:07:13,374 --> 01:07:16,215
What about an object
which is accelerating?
1050
01:07:16,239 --> 01:07:19,518
Then that would be represented
by a curved line.
1051
01:07:19,552 --> 01:07:22,141
This is the world line
of the object.
1052
01:07:28,423 --> 01:07:30,218
Now let's think of the sun,
1053
01:07:30,253 --> 01:07:32,531
that again,
thinking of it as stationary
1054
01:07:32,565 --> 01:07:34,567
would be represented
by a straight line
1055
01:07:34,602 --> 01:07:37,777
and the Earth,
in orbit around the sun,
1056
01:07:37,846 --> 01:07:40,401
would be represented
by a spiral line.
1057
01:07:43,093 --> 01:07:46,441
But then the Earth, as we know,
1058
01:07:46,510 --> 01:07:49,168
is in free fall and should
therefore be represented
1059
01:07:49,203 --> 01:07:52,113
by as straight a line
as you can draw.
1060
01:07:52,137 --> 01:07:55,450
And how is it that it's drawn
as this spiral line?
1061
01:07:55,519 --> 01:07:58,602
Well, this is because
the space-time is
really curved.
1062
01:07:58,626 --> 01:08:02,285
Now, remember
our deformed billiard table,
1063
01:08:02,354 --> 01:08:06,323
the space then would be
warped in a certain way.
1064
01:08:06,392 --> 01:08:11,880
And as the space evolves
to give us our
space-time picture,
1065
01:08:11,915 --> 01:08:14,711
the whole space-time
is slightly deformed.
1066
01:08:14,745 --> 01:08:17,576
And this is why
the apparently curved picture
1067
01:08:17,610 --> 01:08:19,992
of a spiral motion of the Earth
1068
01:08:20,061 --> 01:08:23,375
is really as straight
a line as you can have
in this curved geometry.
1069
01:08:27,103 --> 01:08:31,107
USTINOV: And I gather
that I feel the burden
of gravity here on Earth
1070
01:08:31,141 --> 01:08:35,421
because I go against
the grain of space-time.
1071
01:08:37,285 --> 01:08:39,391
PENROSE: Gravity feels
the same as acceleration
1072
01:08:39,425 --> 01:08:41,990
but, according to Einstein,
in an important sense,
1073
01:08:42,014 --> 01:08:44,948
gravity is the same
as acceleration.
1074
01:08:44,982 --> 01:08:49,055
In a gravitational field
things behave as they do
1075
01:08:49,090 --> 01:08:51,827
in a space free of gravitation.
1076
01:08:51,851 --> 01:08:56,408
If one introduces
a reference system
which is accelerated.
1077
01:08:56,442 --> 01:08:58,513
Do you want me to try it?
1078
01:08:58,582 --> 01:09:00,782
PENROSE: Try it. Never get off the ground
with me in it.
1079
01:09:02,655 --> 01:09:07,326
USTINOV: What Einstein
called a reference system
which is accelerated
1080
01:09:07,350 --> 01:09:09,938
was for me a curiously
dumpy helicopter
1081
01:09:09,973 --> 01:09:13,010
to be flown
as delicately as possible.
1082
01:09:16,531 --> 01:09:18,533
I'd ridden
some awkward steeds
for the movies
1083
01:09:18,602 --> 01:09:22,468
but nothing quite
as undignified as
doctor's scales.
1084
01:09:24,263 --> 01:09:25,609
[HELICOPTER BLADES WHIRRING]
1085
01:09:28,543 --> 01:09:31,684
As the helicopter
lurched upward,
my weight increased.
1086
01:09:31,719 --> 01:09:35,412
Each brief acceleration
adding pseudo-gravity.
1087
01:09:40,383 --> 01:09:44,939
Whenever we climbed steadily
or hovered, my weight
went back to normal.
1088
01:09:46,699 --> 01:09:50,058
And when the pilot
let the machine
accelerate downwards,
1089
01:09:50,082 --> 01:09:54,949
a nasty feeling that...
"Oh! How the pounds
melted away."
1090
01:09:57,572 --> 01:10:00,955
In some neglected
slot machine of my mind
1091
01:10:00,989 --> 01:10:03,406
a penny dropped.
1092
01:10:03,475 --> 01:10:07,213
When a vehicle accelerates,
lurching in one direction,
1093
01:10:07,237 --> 01:10:09,481
all its loose contents
are left behind
1094
01:10:09,515 --> 01:10:12,760
and seem to fall
in the opposite direction.
1095
01:10:12,829 --> 01:10:16,729
As the master said,
"It's just like gravity."
1096
01:10:18,179 --> 01:10:23,288
Acceleration could also put me
on different scales of time.
1097
01:10:23,805 --> 01:10:25,842
Stand by, Albert.
1098
01:10:28,776 --> 01:10:33,229
PENROSE: It's not only gravity
that affects the rate
of a clock
1099
01:10:33,263 --> 01:10:34,989
and sew the passage of time,
1100
01:10:35,921 --> 01:10:38,682
even motion can do that.
1101
01:10:38,717 --> 01:10:42,455
And Einstein showed that
already in 1905,
1102
01:10:42,479 --> 01:10:46,242
ten years before he developed
the general theory
of relativity.
1103
01:10:47,967 --> 01:10:51,143
What Einstein showed
was that if an observer
1104
01:10:51,212 --> 01:10:55,734
moves out
into interstellar space
at high speed
1105
01:10:55,768 --> 01:10:58,471
and finding himself
amongst the stars,
1106
01:10:58,495 --> 01:11:02,430
then turns round
and comes back at
close to the speed of light,
1107
01:11:02,465 --> 01:11:05,951
while the journey for him
will seem short,
1108
01:11:05,985 --> 01:11:07,539
for the people who stay at home
1109
01:11:07,573 --> 01:11:09,748
it will seem much longer.
1110
01:11:09,782 --> 01:11:14,477
For instance, he will find
that he has aged less
during that journey
1111
01:11:14,546 --> 01:11:16,893
than the person
who has stayed at home.
1112
01:11:16,927 --> 01:11:19,033
[TAPE FAST FORWARDING]
1113
01:11:22,139 --> 01:11:23,555
[SIGHS]
1114
01:11:23,589 --> 01:11:25,764
A little lonely
up here in space.
1115
01:11:27,352 --> 01:11:31,079
USTINOV: Long after I'd fired
my motors to turn for home,
1116
01:11:31,114 --> 01:11:33,989
my twin brother Albert
was still receiving signals
1117
01:11:34,013 --> 01:11:36,878
sent by me
on the outward leg
of the journey.
1118
01:11:37,431 --> 01:11:40,296
[DELAYED SPEECH]
1119
01:11:43,471 --> 01:11:47,682
USTINOV: Again, time seemed
to me to pass normally.
1120
01:11:47,751 --> 01:11:51,755
But it was
in this melancholy phase
of my return journey
1121
01:11:51,790 --> 01:11:56,173
that I observed poor Albert
growing older by the hour.
1122
01:11:57,313 --> 01:11:58,659
[TAPE FAST FORWARDING]
1123
01:12:04,043 --> 01:12:06,114
USTINOV: Just as for the visit
to the black hole,
1124
01:12:06,149 --> 01:12:09,221
this high speed
relativistic flight plan
1125
01:12:09,290 --> 01:12:13,501
took me on a one-way ticket
into the twenty-first century.
1126
01:12:24,788 --> 01:12:27,170
Although he lived
before the space age,
1127
01:12:27,204 --> 01:12:31,208
Einstein made many
imaginary journeys like this.
1128
01:12:31,277 --> 01:12:33,210
Gedanken experiments.
1129
01:12:33,245 --> 01:12:36,110
"Thought experiments,"
the physicists called them.
1130
01:12:36,144 --> 01:12:37,422
[WIND WHOOSHING]
1131
01:12:38,975 --> 01:12:42,230
"One could imagine
that the organism,
1132
01:12:42,254 --> 01:12:45,706
"after an arbitrarily
lengthy flight,
1133
01:12:45,740 --> 01:12:51,194
"could be returned
to its original spot in
a scarcely altered condition
1134
01:12:51,228 --> 01:12:56,555
"while corresponding organisms
which had remained in
their original positions
1135
01:12:56,579 --> 01:13:00,548
"had long since given way
to new generations."
1136
01:13:01,549 --> 01:13:03,379
Einstein said that
many years ago,
1137
01:13:03,413 --> 01:13:08,694
but, uh, people for many years
didn't really accept
that notion.
1138
01:13:08,729 --> 01:13:12,940
It, uh, in fact, was
the source of much argument
1139
01:13:13,009 --> 01:13:17,013
and was elevated
at times into the notion
of a paradox.
1140
01:13:17,047 --> 01:13:21,949
But now,
with very fast moving
atomic particles,
1141
01:13:22,018 --> 01:13:26,919
we have displayed
this affect with
extreme accuracy.
1142
01:13:26,954 --> 01:13:32,718
Most precisely,
atomic particles in
a storage ring at CERN,
1143
01:13:32,753 --> 01:13:35,411
so-called new mesons
which normally live
1144
01:13:35,445 --> 01:13:37,723
a very fleeting fraction
of a second,
1145
01:13:37,758 --> 01:13:40,519
perhaps a millionth
or two millionths of a second,
1146
01:13:40,554 --> 01:13:44,430
have been shown to
have their lives extended
1147
01:13:44,454 --> 01:13:46,974
by a factor of thirty or so
1148
01:13:47,043 --> 01:13:51,841
just by having them move
at speeds very close
to the speed of light.
1149
01:13:54,982 --> 01:13:58,133
USTINOV: Well, I understand
that this is possible
for particles
1150
01:13:58,157 --> 01:14:00,953
but it does sound rather
like science fiction to me
1151
01:14:00,988 --> 01:14:03,439
and like fantasy, would it be...
1152
01:14:03,473 --> 01:14:05,786
Would it be really
possible for this to happen?
1153
01:14:06,821 --> 01:14:07,995
For people, I mean.
1154
01:14:08,029 --> 01:14:10,929
Well,
this is a matter of faith,
not a matter of science.
1155
01:14:10,963 --> 01:14:15,071
There's nothing in principle,
I believe, that stands
in the way
1156
01:14:15,105 --> 01:14:17,901
of getting one up to speeds, uh,
1157
01:14:17,936 --> 01:14:20,007
that are a significant fraction
1158
01:14:20,076 --> 01:14:22,492
of the velocity of light.
1159
01:14:22,527 --> 01:14:25,426
And, uh, when one thinks
of the incredible things
1160
01:14:25,461 --> 01:14:28,602
that we do with
instruments these days,
1161
01:14:28,636 --> 01:14:32,778
measuring with accelerators
that are many miles long,
1162
01:14:32,813 --> 01:14:35,643
timed to precisions of
billionths of a second,
1163
01:14:35,678 --> 01:14:40,027
I would be the last
to think it's impossible,
and won't be done.
1164
01:14:40,096 --> 01:14:42,132
After all, we did send men
to the moon and look
1165
01:14:42,167 --> 01:14:45,515
for how many centuries
that seemed impossible.
1166
01:14:45,550 --> 01:14:48,356
Presumably, one of the great
advantages there would be
1167
01:14:48,380 --> 01:14:52,187
if human beings ever
attempted to travel
between the stars,
1168
01:14:52,211 --> 01:14:57,182
that you not only gain in
an apparent extension of life,
1169
01:14:57,216 --> 01:15:00,565
as compared with the Earth,
but also you can travel
greater distances
1170
01:15:00,634 --> 01:15:05,718
than you would think possible
by normal reckoning of
speeds from the Earth.
1171
01:15:05,742 --> 01:15:08,203
I would say it's not
only an advantage,
it's a requirement
1172
01:15:08,227 --> 01:15:11,576
because distances
to other, uh, stars,
1173
01:15:11,645 --> 01:15:14,727
and their presumed planets
are so great that
there's no way
1174
01:15:14,751 --> 01:15:18,134
we're going to ever
explore them if we don't
stretch out our lives,
1175
01:15:18,168 --> 01:15:19,342
our time scale.
1176
01:15:24,934 --> 01:15:28,569
USTINOV: It was one of
Einstein's earliest
ideas in relativity
1177
01:15:28,593 --> 01:15:33,494
that you could distort
time and space just by
traveling fast enough.
1178
01:15:36,221 --> 01:15:39,845
We've now left gravity
and general relativity
aside for a while
1179
01:15:39,880 --> 01:15:42,917
to hear instead
about special relativity
1180
01:15:42,986 --> 01:15:45,506
and the strange
effects of motion.
1181
01:15:48,095 --> 01:15:52,306
Now let's imagine
that these bikes
are capable of, say,
1182
01:15:52,340 --> 01:15:54,342
half the speed of light.
1183
01:15:54,377 --> 01:15:56,379
That's what
their speedometers
show anyway,
1184
01:15:56,413 --> 01:15:58,692
fractions of C,
the speed of light.
1185
01:16:06,113 --> 01:16:08,115
What kinds
of Einsteinian effects
1186
01:16:08,184 --> 01:16:10,842
can we illustrate
with bikes like these?
1187
01:16:10,876 --> 01:16:13,396
Perhaps you should start
with the simplest point
of all.
1188
01:16:13,430 --> 01:16:15,053
From the point of view
of the rider,
1189
01:16:15,087 --> 01:16:18,574
he's at rest and
it's the landscape
that's rushing towards him.
1190
01:16:21,438 --> 01:16:23,451
In Einstein's
democratic universe,
1191
01:16:23,475 --> 01:16:26,512
that point of view
is just as valid
as yours or mine.
1192
01:16:29,136 --> 01:16:31,414
And then recall
the Doppler effect,
1193
01:16:31,448 --> 01:16:33,519
the change in frequency
in color of light.
1194
01:16:36,350 --> 01:16:40,009
An object rushing towards you
looks blue because the light
gets crowded together.
1195
01:16:41,286 --> 01:16:42,701
It has a higher frequency.
1196
01:16:44,530 --> 01:16:46,291
[RESONATING]
1197
01:16:46,325 --> 01:16:50,226
When it's going away
it looks red because
the light gets stretched out
1198
01:16:50,260 --> 01:16:51,952
and then it has
a lower frequency.
1199
01:16:58,061 --> 01:17:00,546
CALDER: I'd like to emphasize
something there, Peter.
1200
01:17:00,581 --> 01:17:02,928
Compared with ordinary
white light,
1201
01:17:02,963 --> 01:17:06,932
blue light has
a higher frequency
and more energy too.
1202
01:17:07,933 --> 01:17:09,497
[RESONATING]
1203
01:17:09,521 --> 01:17:15,192
But red light represents
a low frequency and
less energy.
1204
01:17:15,216 --> 01:17:19,162
BRECHER: Einstein made
two important discoveries
about the Doppler effect.
1205
01:17:19,186 --> 01:17:23,155
First, it doesn't make
any difference who is said
to be moving.
1206
01:17:23,190 --> 01:17:25,502
It's just the relative speed
that counts.
1207
01:17:27,090 --> 01:17:29,828
Einstein's second discovery
about the Doppler effect
1208
01:17:29,852 --> 01:17:32,648
is that when
a high speed vehicle
is just passing you,
1209
01:17:32,682 --> 01:17:34,201
strange things happen.
1210
01:17:34,270 --> 01:17:35,350
Imagine that you were
quick enough to
1211
01:17:35,374 --> 01:17:36,721
photograph it with your camera.
1212
01:17:37,514 --> 01:17:38,654
You ready, Peter?
1213
01:17:40,034 --> 01:17:41,311
[CAMERA SHUTTER CLICKS]
1214
01:17:41,346 --> 01:17:43,693
As the vehicle passes us by,
1215
01:17:43,728 --> 01:17:46,144
you'd think it would be
neither red-shifted
nor blue-shifted
1216
01:17:46,178 --> 01:17:49,009
because it's moving
perpendicular to
our line of sight.
1217
01:17:49,043 --> 01:17:51,011
But, in fact,
it's slightly red-shifted.
1218
01:17:51,045 --> 01:17:53,599
What's more,
it's rotated away from us.
1219
01:17:55,878 --> 01:17:56,878
[RESONATING]
1220
01:17:59,329 --> 01:18:00,917
CALDER: Not shortened.
1221
01:18:00,986 --> 01:18:04,300
Many accounts of relativity
would have the bike
squeezed short.
1222
01:18:04,334 --> 01:18:07,199
No, it still appears
to be undistorted
1223
01:18:07,234 --> 01:18:08,994
but slightly
rotated away from us.
1224
01:18:13,205 --> 01:18:15,045
But from the point of view
of the rider,
1225
01:18:15,069 --> 01:18:17,658
it could be
very peculiar distortions
of the scenery
1226
01:18:17,693 --> 01:18:21,386
if you rode past buildings,
say, almost at
the speed of light.
1227
01:18:27,116 --> 01:18:28,921
Perhaps the first thing
you notice...[CAMERA SHUTTER CLICKS]
1228
01:18:28,945 --> 01:18:31,154
...is the building
and the truck
curve in a little.
1229
01:18:34,123 --> 01:18:37,816
Then, as you speed up,
you see that they seem
to be twisted towards you.
1230
01:18:37,851 --> 01:18:38,851
[CAMERA SHUTTER CLICKS]
1231
01:18:41,337 --> 01:18:44,064
Indeed, as your speed
increases closer
and closer
1232
01:18:44,098 --> 01:18:47,653
to the speed of light,
you start seeing the far sides
of the building and truck.
1233
01:18:47,688 --> 01:18:48,907
[CAMERA SHUTTER CLICKS]
1234
01:18:48,931 --> 01:18:51,485
You seem to be seeing
right around the corners.
1235
01:18:52,935 --> 01:18:54,522
It's like walking
through a rain storm
1236
01:18:54,557 --> 01:18:57,698
when your front gets wet
and your back stays dry.
1237
01:18:57,733 --> 01:19:00,494
The light approaches you
from unexpected directions.
1238
01:19:04,774 --> 01:19:09,158
CALDER: Consider two bicycles
coming at each other at
close to the speed of light.
1239
01:19:10,297 --> 01:19:13,058
You might think that
their combined speed,
1240
01:19:13,093 --> 01:19:15,336
the rate at which
they are coming together,
1241
01:19:15,371 --> 01:19:16,890
is faster than light.
1242
01:19:18,995 --> 01:19:22,447
But from each rider's
point of view, it's not
like that at all.
1243
01:19:26,589 --> 01:19:29,661
Their combined speed,
as they measure it,
1244
01:19:29,730 --> 01:19:32,526
always remains less
than the speed of light.
1245
01:19:36,841 --> 01:19:43,088
USTINOV: Einstein launched
his disconcerting ideas
from very simple premises.
1246
01:19:43,123 --> 01:19:47,828
The riders demonstrated
why time runs slowly in
a fast moving vehicle.
1247
01:19:47,852 --> 01:19:51,797
They just rode in company
and threw a ball to
represent a signal,
1248
01:19:51,821 --> 01:19:53,478
a flash of light.
1249
01:19:57,620 --> 01:20:02,349
From their point of view,
the light went straight
across between them.
1250
01:20:02,418 --> 01:20:06,940
But from our point of view,
as onlookers watching
the bikes go by,
1251
01:20:06,974 --> 01:20:11,668
the signal went obliquely
and on a longer path.
1252
01:20:11,703 --> 01:20:14,326
But light always moves
at the same speed
1253
01:20:14,361 --> 01:20:18,468
so that the time
it takes for the signal
to go from there to here
1254
01:20:18,503 --> 01:20:19,918
takes longer from
our point of view
1255
01:20:19,953 --> 01:20:21,609
than from the point
of view of the riders.
1256
01:20:22,921 --> 01:20:24,785
So Einstein tells us
1257
01:20:24,820 --> 01:20:27,522
that their clocks
in the moving frame
1258
01:20:27,546 --> 01:20:30,791
move slower than ours
in exactly proportioned
1259
01:20:30,826 --> 01:20:33,967
of this line to this line.
1260
01:20:38,557 --> 01:20:42,389
CALDER: High speed travel
also makes you seem heavier.
1261
01:20:42,423 --> 01:20:47,843
Time for rapidly moving bikes
slows down and it accelerates
more sluggishly.
1262
01:20:49,016 --> 01:20:51,329
Mass means resistance
to acceleration
1263
01:20:51,363 --> 01:20:55,436
and the bike's mass
piles on as it gets
near the speed of light.
1264
01:21:00,303 --> 01:21:03,720
In fact, it continues
to grow more massive
without limit
1265
01:21:03,755 --> 01:21:05,653
as it gets very close
to the speed of light
1266
01:21:05,688 --> 01:21:08,864
so that, in fact,
it never can go
faster than light.
1267
01:21:10,244 --> 01:21:11,901
But from the point
of view of the rider,
1268
01:21:11,970 --> 01:21:13,869
his mass seems
the same as usual.
1269
01:21:18,701 --> 01:21:21,428
When Einstein realized
just how much
the way things look
1270
01:21:21,497 --> 01:21:23,406
depend on where you stand,
1271
01:21:23,430 --> 01:21:25,328
he also saw a danger.
1272
01:21:25,363 --> 01:21:28,884
Because, he reasoned,
the laws of physics
must be the same
1273
01:21:28,918 --> 01:21:31,576
for the rider, as for
the fixed observer.
1274
01:21:35,131 --> 01:21:38,755
Special relativity
was born brilliantly
out of that requirement.
1275
01:21:38,790 --> 01:21:41,103
But the price
Einstein exacted from us
1276
01:21:41,172 --> 01:21:45,797
was the scrapping of
the old ideas about time.
1277
01:21:45,866 --> 01:21:48,662
Einstein realized that
although each person's
view of events
1278
01:21:48,696 --> 01:21:50,422
is a little different,
1279
01:21:50,457 --> 01:21:53,391
everyone's view
is equally valid.
1280
01:21:53,425 --> 01:21:58,396
And yet we are observing,
all of us, the same
laws of physics.
1281
01:22:00,950 --> 01:22:04,954
USTINOV: And the touchstone
for the reliability
of physical laws
1282
01:22:05,023 --> 01:22:07,750
was Einstein's old obsession,
1283
01:22:07,784 --> 01:22:09,925
the speed of light
remaining constant
1284
01:22:09,959 --> 01:22:12,272
amid all the commotion
of the cosmos.
1285
01:22:14,101 --> 01:22:17,322
CALDER: Now, because
of its motion in orbit
around the sun,
1286
01:22:17,346 --> 01:22:22,938
our Earth is traveling
at a speed of about
30 kilometers a second.
1287
01:22:22,972 --> 01:22:26,803
If the principle of relativity
were not valid,
1288
01:22:26,838 --> 01:22:28,643
we should expect
the laws of nature
1289
01:22:28,667 --> 01:22:33,086
to depend on
the Earth's direction
of motion at any moment.
1290
01:22:33,120 --> 01:22:37,480
But the most
careful observations
have never revealed
1291
01:22:37,504 --> 01:22:41,887
any lack of prevalence
of different directions.
1292
01:22:41,922 --> 01:22:44,925
This is a very powerful argument
1293
01:22:44,960 --> 01:22:48,964
in favor of
the principle of relativity.
1294
01:22:50,482 --> 01:22:54,141
USTINOV: But Einstein's
revelations shook the planet.
1295
01:22:54,176 --> 01:22:57,248
From the reasoning
of special relativity
1296
01:22:57,282 --> 01:23:02,287
emerged a law
of creation and destruction.
1297
01:23:08,362 --> 01:23:12,332
It was time for us
to consider the realm
of the atom,
1298
01:23:12,366 --> 01:23:18,683
where relativistic events
are more usual than on
the roads of Texas.
1299
01:23:21,858 --> 01:23:24,171
First, for real motorcycles,
1300
01:23:24,206 --> 01:23:26,311
the velocities are much too low
1301
01:23:26,346 --> 01:23:29,211
for the effects
of relativity to
be noticeable.
1302
01:23:29,280 --> 01:23:31,489
Even, uh, with a spacecraft,
1303
01:23:31,523 --> 01:23:33,974
circling the Earth
every 90 minutes,
1304
01:23:34,009 --> 01:23:36,056
the speeds are too low.
1305
01:23:36,080 --> 01:23:40,222
They're being moved, in fact,
about one forty-thousandth
the speed of light
1306
01:23:40,291 --> 01:23:44,364
and, uh, their increase
in mass due to motion
1307
01:23:44,398 --> 01:23:47,884
is less than
one part in
a thousand million.
1308
01:23:48,368 --> 01:23:49,610
USTINOV: Hmm.
1309
01:23:49,679 --> 01:23:53,821
Astronomers looking
at distant stars
and distant objects
1310
01:23:53,856 --> 01:23:59,389
are seeing systems moving
with a substantial fraction
of the velocity of light.
1311
01:23:59,413 --> 01:24:01,519
And when we enter
the atomic realm,
1312
01:24:01,553 --> 01:24:04,660
we, uh, enter into an area where
1313
01:24:04,694 --> 01:24:08,491
the relativistic effects
are very noticeable.
1314
01:24:08,526 --> 01:24:10,079
Even on your television screen,
1315
01:24:10,148 --> 01:24:13,255
the electrons that paint
the television screen,
1316
01:24:13,289 --> 01:24:17,259
are moving with perhaps
20 to 30% of
the velocity of light.
1317
01:24:17,293 --> 01:24:22,747
And, uh, thereby their mass
is increased to the order
of a percent or so.
1318
01:24:22,781 --> 01:24:26,416
Out at Stanford, at the
linear accelerator center,
1319
01:24:26,440 --> 01:24:30,375
we produce the highest
energy electrons in the world.
1320
01:24:30,410 --> 01:24:32,895
They come so close
to the speed of light
1321
01:24:32,929 --> 01:24:36,726
that their mass is increased
by a factor of 40,000,
1322
01:24:36,761 --> 01:24:38,763
compared to what
they started with.
1323
01:24:42,974 --> 01:24:47,772
As a result of this very high
velocity and high energy
that they acquire,
1324
01:24:47,841 --> 01:24:49,957
their clocks are slowed down,
1325
01:24:49,981 --> 01:24:51,614
and they don't realize
that they have moved
1326
01:24:51,638 --> 01:24:53,260
a full two-mile
of our accelerator.
1327
01:24:53,295 --> 01:24:55,538
In fact, from
the electron's point of view,
1328
01:24:55,573 --> 01:24:56,953
their clocks
are moving so slowly
1329
01:24:56,988 --> 01:24:58,931
they think they have gone
only two and a half feet
1330
01:24:58,955 --> 01:25:01,682
by the time they come
to the end of the accelerator.
1331
01:25:01,717 --> 01:25:03,270
[THUNDER CRASHING]
1332
01:25:07,792 --> 01:25:12,072
At the end of the accelerator,
we also have a storage ring,
1333
01:25:12,107 --> 01:25:16,490
so-called sphere ring,
where we smash the particles
into one another.
1334
01:25:16,559 --> 01:25:18,630
We create new matter.
1335
01:25:20,322 --> 01:25:24,464
And in this way we can
very accurately measure
1336
01:25:24,498 --> 01:25:27,915
the conversion of energy
of motion into matter.
1337
01:25:27,950 --> 01:25:31,826
And into mass. And in this way
confirm with great accuracy
1338
01:25:31,850 --> 01:25:36,476
the Einstein equation, E = mc2.
1339
01:25:37,270 --> 01:25:39,134
What an equation that is.
1340
01:25:39,168 --> 01:25:40,825
It looks so innocent.
1341
01:25:40,894 --> 01:25:44,322
E... Energy, M... Mass,
1342
01:25:44,346 --> 01:25:47,980
and C...
Not the speed of light
1343
01:25:48,004 --> 01:25:49,661
but the square
of the speed of light.
1344
01:25:49,730 --> 01:25:51,525
An enormous number.
1345
01:25:51,594 --> 01:25:55,080
So that a little mass
is worth a lot of energy.
1346
01:25:56,116 --> 01:25:57,773
BRECHER: It's hard
to appreciate
1347
01:25:57,807 --> 01:26:01,363
what an enormous
leap of intuition
and imagination
1348
01:26:01,432 --> 01:26:05,298
it took to come
to this simple formula.
1349
01:26:05,332 --> 01:26:08,646
Einstein had been thinking,
from the age of 16 to 26,
1350
01:26:08,680 --> 01:26:13,685
consistently about
the nature of light
and electromagnetic radiation
1351
01:26:13,720 --> 01:26:19,381
and almost as a by-product
of his... Of his, uh,
thinking on this subject,
1352
01:26:19,450 --> 01:26:22,049
he came to
the following conclusion,
1353
01:26:22,073 --> 01:26:25,283
that if you look at light,
say, from the sun,
1354
01:26:25,318 --> 01:26:27,882
and if you were moving
towards the sun,
1355
01:26:27,906 --> 01:26:30,530
as we've already discussed,
the light would become bluer.
1356
01:26:32,428 --> 01:26:37,064
Now, the blue light has more
energy than the white
light we normally see,
1357
01:26:37,088 --> 01:26:40,643
and therefore, he reasoned,
there must be more energy
1358
01:26:40,678 --> 01:26:42,369
apparently coming from the sun.
1359
01:26:44,509 --> 01:26:47,823
But if that energy is not
drawn from any change
in the motion of the sun,
1360
01:26:47,857 --> 01:26:52,276
it must mean that
that energy is coming
from the mass itself.
1361
01:26:53,898 --> 01:26:55,589
And so he concluded
1362
01:26:55,624 --> 01:27:00,284
that the mass of the sun
itself is converted
directly into energy.
1363
01:27:00,353 --> 01:27:07,118
He then made the enormous leap
to generalize this result
to all forms of energy.
1364
01:27:07,187 --> 01:27:09,924
In the 19th century,
there had been
energy of motion,
1365
01:27:09,948 --> 01:27:13,366
and energy of light,
energy of heat,
but not inter-convertible.
1366
01:27:13,400 --> 01:27:15,275
And so he came to
the startling conclusion
1367
01:27:15,299 --> 01:27:18,923
that all mass
and all energy
are in fact equivalent.
1368
01:27:20,787 --> 01:27:23,893
"We are led to the more
general conclusion
1369
01:27:23,928 --> 01:27:28,657
"that the mass of an object
is a measure of
its energy content.
1370
01:27:29,623 --> 01:27:31,763
"It is not impossible
1371
01:27:31,798 --> 01:27:35,042
"that with materials whose
energy content is variable
1372
01:27:35,077 --> 01:27:39,264
"to a high degree,
for example with radium salt,
1373
01:27:39,288 --> 01:27:43,396
"the theory may be
successfully put to the test."
1374
01:27:43,430 --> 01:27:48,884
What Einstein is noting here
is that the energy released
in nuclear reactions
1375
01:27:48,918 --> 01:27:54,752
is so great that there is
actually a measurable change
1376
01:27:54,786 --> 01:27:56,167
in the mass.
1377
01:27:56,236 --> 01:28:02,277
That can be detected
and his formula
can be verified.
1378
01:28:02,311 --> 01:28:05,832
The, uh, nuclear
burning together
1379
01:28:05,901 --> 01:28:10,043
with the Einstein
relation, E=mc2,
1380
01:28:10,077 --> 01:28:12,470
solved a long-standing riddle,
1381
01:28:12,494 --> 01:28:15,807
namely, how is it that
the stars, the sun,
1382
01:28:15,842 --> 01:28:21,710
can burn for billions of years
without running out
of, uh, material?
1383
01:28:22,642 --> 01:28:25,403
This equation, E=mc2,
1384
01:28:25,438 --> 01:28:27,750
and the efficiency
of nuclear burning,
1385
01:28:27,785 --> 01:28:32,583
were tested
quantitatively in 1932,
1386
01:28:32,617 --> 01:28:36,311
by Cockcroft and Walton
with their accelerator.
1387
01:28:36,345 --> 01:28:39,521
They verified it
for the first time.
1388
01:28:39,555 --> 01:28:43,697
WHEELER: But it was
a long time before any
practical use was made of it.
1389
01:28:43,766 --> 01:28:46,942
Einstein was hounded
out of Germany,
1390
01:28:46,976 --> 01:28:48,851
he came to Princeton,
1391
01:28:48,875 --> 01:28:52,637
where I had the pleasure
of seeing him
after his arrival.
1392
01:28:52,672 --> 01:28:56,341
But it was five years
from that until
that fateful day
1393
01:28:56,365 --> 01:28:59,195
when I went down
to the pier in New York,
1394
01:28:59,264 --> 01:29:01,864
and a ship came in
with Niels Bohr,
1395
01:29:01,888 --> 01:29:05,961
and the word of
the discovery of
the fission of uranium.
1396
01:29:07,272 --> 01:29:10,217
January 16, 1939,
1397
01:29:10,241 --> 01:29:14,877
and not long after
that Einstein wrote
that fateful letter
1398
01:29:14,901 --> 01:29:18,180
to Roosevelt with
all its consequences.
1399
01:29:18,214 --> 01:29:20,917
USTINOV: Hmm.
1400
01:29:20,941 --> 01:29:26,430
USTINOV: "Extremely powerful
bombs of a new type may
thus be constructed.
1401
01:29:26,499 --> 01:29:30,399
"I understand that Germany
has actually stopped
the sale of uranium
1402
01:29:30,468 --> 01:29:33,229
"from the
Czechoslovakian mines."
1403
01:29:35,093 --> 01:29:39,512
And it was hardly 200 miles
from here across the desert,
1404
01:29:39,546 --> 01:29:43,239
that that first
dramatic explosion took place
1405
01:29:43,308 --> 01:29:46,484
that brought us into
the true atomic era.
1406
01:29:51,696 --> 01:29:53,698
[EXPLOSION]
1407
01:29:59,117 --> 01:30:02,258
DRELL: Einstein,
who set it all in train,
1408
01:30:02,293 --> 01:30:05,365
was appalled by
the nuclear arms race.
1409
01:30:05,400 --> 01:30:10,474
It's ironic that this humble,
gentle man who had been
an avowed pacifist
1410
01:30:10,543 --> 01:30:16,100
should now be etched in
the history of mankind as
the father of nuclear weapons.
1411
01:30:16,134 --> 01:30:18,274
He believed, as do many today,
1412
01:30:18,309 --> 01:30:20,276
including many scientists
who are familiar with
1413
01:30:20,311 --> 01:30:22,969
the devastating effects
of these weapons,
1414
01:30:23,038 --> 01:30:26,075
that survival in a world
with nuclear weapons
1415
01:30:26,110 --> 01:30:29,734
is one of the great
challenges of our generation.
1416
01:30:29,769 --> 01:30:32,955
It was, I believe,
his last official act,
1417
01:30:32,979 --> 01:30:37,880
to endorse a manifesto in 1955
1418
01:30:37,915 --> 01:30:41,884
with Bertrand Russell,
which I believe
you have here.
1419
01:30:41,919 --> 01:30:44,404
Yes.
1420
01:30:44,439 --> 01:30:50,375
"We appeal to you
as human beings
to human beings.
1421
01:30:50,410 --> 01:30:54,518
"Remember your humanity
and forget the rest.
1422
01:30:54,587 --> 01:30:59,143
"If you can do so,
the way lies open
to a new paradise.
1423
01:30:59,177 --> 01:31:06,633
"If you cannot, there lies
before you the risk
of universal death."
1424
01:31:06,668 --> 01:31:09,774
I think, in talking about
Einstein's great achievement,
1425
01:31:09,809 --> 01:31:14,503
we should really stress
the fact that it lies at
the basis of all life.
1426
01:31:14,538 --> 01:31:17,230
The nuclear weapons
are only a small by-product
1427
01:31:17,264 --> 01:31:19,232
of human folly.
1428
01:31:21,476 --> 01:31:23,754
Even when I strike this match,
1429
01:31:23,788 --> 01:31:27,492
a minute amount of the mass
is converted into energy.
1430
01:31:27,516 --> 01:31:29,839
If I took all the mass
in this match,
1431
01:31:29,863 --> 01:31:32,556
and converted it
into free energy,
1432
01:31:32,625 --> 01:31:35,282
there's enough energy here
to lift the entire mountain,
1433
01:31:35,317 --> 01:31:37,664
on which we're sitting now,
about ten feet off the ground.
1434
01:31:38,872 --> 01:31:43,049
This energy plays a role
in the hum of a violin,
1435
01:31:43,083 --> 01:31:46,742
in the growing plants here,
and in fact in the expansion
of the universe.
1436
01:31:49,227 --> 01:31:54,336
All of astrophysics is
about nature's attempt
1437
01:31:54,370 --> 01:31:57,650
to release the energy
hidden in ordinary matter.
1438
01:31:57,684 --> 01:32:01,861
Energy defined by
the equation E equals MC2.
1439
01:32:01,895 --> 01:32:06,048
USTINOV: So I learned
to perceive the sun,
hot enough in Texas,
1440
01:32:06,072 --> 01:32:10,525
as a natural nuclear furnace
and a typical star.
1441
01:32:10,559 --> 01:32:15,668
Energy can create matter,
so matter has hidden energy.
1442
01:32:15,702 --> 01:32:19,810
Falling down, like the apple,
can liberate some of it.
1443
01:32:19,844 --> 01:32:23,089
So Wallace Sargent led me
back to gravity,
1444
01:32:23,158 --> 01:32:26,471
saying it can overwhelm a star.
1445
01:32:28,163 --> 01:32:31,200
SARGENT: When the sun
grows old, it will
first of all
1446
01:32:31,235 --> 01:32:33,030
become a red giant,
in which it becomes
1447
01:32:33,064 --> 01:32:36,896
much bigger
and a little cooler
than it is now.
1448
01:32:38,104 --> 01:32:40,727
At this time, the Earth
will be consumed,
1449
01:32:40,762 --> 01:32:44,559
but fortunately,
it will not happen for
several more billion years.
1450
01:32:46,422 --> 01:32:50,920
After that,
the sun will shrink
and become a white dwarf
1451
01:32:50,944 --> 01:32:52,636
which is about the
size of the Earth.
1452
01:32:55,086 --> 01:32:59,056
During this time,
a lot of hidden energy
will be released,
1453
01:32:59,090 --> 01:33:01,265
but not as much as
has been released by
1454
01:33:01,299 --> 01:33:05,062
nuclear burning at
earlier stages of
its evolution.
1455
01:33:06,615 --> 01:33:09,791
Stars much more
massive than the sun
1456
01:33:09,860 --> 01:33:11,931
end their lives as supernovae,
1457
01:33:11,965 --> 01:33:14,865
that is they undergo
gigantic explosions.
1458
01:33:14,899 --> 01:33:18,627
During this event,
the inner parts of the star
1459
01:33:18,662 --> 01:33:21,699
is driven inwards
in an enormous implosion.
1460
01:33:23,839 --> 01:33:27,774
This forms a neutron star,
which in turn becomes
a pulsar.
1461
01:33:29,327 --> 01:33:34,747
The matter in
the neutron star
is extraordinarily dense,
1462
01:33:34,781 --> 01:33:37,657
and the atoms
are crushed together,
1463
01:33:37,681 --> 01:33:41,339
and a substantial fraction
of the hidden energy
1464
01:33:41,408 --> 01:33:45,492
originally in the star
is set free.
1465
01:33:45,516 --> 01:33:49,693
Well, so neutron stars exist,
but theoretical calculations
tell us
1466
01:33:49,762 --> 01:33:54,974
that some thing of three
times the mass of the sun
can't exist as a neutron star.
1467
01:33:56,596 --> 01:33:58,850
It's a short step
from a neutron star
1468
01:33:58,874 --> 01:34:01,463
to matter being crushed
by implosion into
a black hole.
1469
01:34:04,155 --> 01:34:07,341
In the case of
a collapsed star,
ten times the sun's mass,
1470
01:34:07,365 --> 01:34:11,542
the resulting black hole
would be only about
40 miles across.
1471
01:34:11,611 --> 01:34:13,717
Nothing could escape
from it, not even light.
1472
01:34:16,754 --> 01:34:18,445
Material falling into
such a black hole
1473
01:34:18,480 --> 01:34:19,837
would liberate tremendous energy
1474
01:34:19,861 --> 01:34:22,011
just before disappearing
into the hole,
1475
01:34:22,035 --> 01:34:24,693
giving out intense x-rays.
1476
01:34:24,762 --> 01:34:27,627
And these x-rays
could be seen
from the Earth,
1477
01:34:27,662 --> 01:34:30,319
and that's in fact how
we could expect to
detect such a thing.
1478
01:34:32,390 --> 01:34:35,024
Well, the x-ray source
called Cygnus X-1
1479
01:34:35,048 --> 01:34:38,327
meets these specifications
and may well be
a black hole.
1480
01:34:38,362 --> 01:34:42,538
And it's sucking
material apparently from
a companion super giant star.
1481
01:34:48,027 --> 01:34:50,557
Well, now we're on Cygnus X-1.
1482
01:34:50,581 --> 01:34:55,379
What we can actually see here
is the companion to the star.
1483
01:34:56,380 --> 01:34:58,071
Not the black hole itself.
1484
01:34:58,140 --> 01:35:01,799
The black hole is
orbiting around the
star that you can see.
1485
01:35:03,076 --> 01:35:07,494
This is a record of
the extra emissions
from Cygnus X-1.
1486
01:35:07,529 --> 01:35:10,152
And you see there's
no regularity in it
1487
01:35:10,187 --> 01:35:12,016
as there would be
if it were a neutron star.
1488
01:35:12,051 --> 01:35:14,191
USTINOV: No, they're not
very regular, are they?
1489
01:35:15,710 --> 01:35:18,160
[BEEPING] The quest for
black holes was, for me,
1490
01:35:18,195 --> 01:35:21,025
the culminating proof
that Einstein's theories
1491
01:35:21,060 --> 01:35:23,372
still inspire the very
latest research.
1492
01:35:24,684 --> 01:35:27,204
It led us to distant
galaxies of stars
1493
01:35:27,238 --> 01:35:31,933
as big as our own Milky Way,
but erupting most violently.
1494
01:35:31,967 --> 01:35:36,914
In order to explain many of
the phenomena out there
in the universe,
1495
01:35:36,938 --> 01:35:41,263
we have to invoke
enormous energy sources.
1496
01:35:41,287 --> 01:35:45,601
And it looks more and more
as though black holes
may be the only possibility
1497
01:35:45,670 --> 01:35:48,570
to provide such large
sources of energy.
1498
01:35:48,604 --> 01:35:53,023
In this kind of theory,
an enormous black hole
with a mass
1499
01:35:53,057 --> 01:35:56,543
probably several billion
times the mass of the sun,
1500
01:35:56,578 --> 01:36:02,308
sits at the center of the
galaxy and releases energy
1501
01:36:02,377 --> 01:36:04,551
in some way, which we
don't yet understand,
1502
01:36:04,586 --> 01:36:09,556
by swallowing entire
stars and gas from
the surrounding galaxy.
1503
01:36:14,320 --> 01:36:16,632
For the past couple of years,
several of us
1504
01:36:16,667 --> 01:36:19,566
have been paying particular
attention to the galaxy M87.
1505
01:36:20,498 --> 01:36:22,293
It's a very distinctive galaxy
1506
01:36:22,328 --> 01:36:26,435
with a jet of luminous matter
poking out at one side.
1507
01:36:28,127 --> 01:36:33,097
M87 is a strong source
of radio waves
and also x-rays.
1508
01:36:33,132 --> 01:36:36,825
And all together,
it's a very energetic galaxy.
1509
01:36:36,860 --> 01:36:40,656
Most of the work
that we've done
has been observations
1510
01:36:40,691 --> 01:36:43,280
at the Kitt Peak
Observatory in Arizona
1511
01:36:43,314 --> 01:36:46,110
and at Palomar Observatory
in California.
1512
01:36:46,145 --> 01:36:48,492
We've used a very
sensitive light detector
1513
01:36:48,526 --> 01:36:51,978
brought out from London
by Alec Boksenberg.
1514
01:36:52,013 --> 01:36:54,774
What we do is to
look at slices of M87
1515
01:36:54,809 --> 01:36:58,329
at different distances
from the center and
use the Doppler shift
1516
01:36:58,364 --> 01:37:03,334
to tell how fast
the stars in the galaxy
are moving around.
1517
01:37:03,369 --> 01:37:07,176
What we find is that
the stars in the
very center of M87
1518
01:37:07,200 --> 01:37:11,618
are moving around
much more rapidly
than we would expect.
1519
01:37:11,653 --> 01:37:14,183
As far as we can see,
they're moving fast
1520
01:37:14,207 --> 01:37:17,359
because they're orbiting
around an invisible object.
1521
01:37:17,383 --> 01:37:19,706
But we can use
the speeds of the stars
1522
01:37:19,730 --> 01:37:22,733
to estimate the mass
of this invisible object.
1523
01:37:22,802 --> 01:37:27,058
It turns out to be about
5,000 million times
as big as the sun.
1524
01:37:27,082 --> 01:37:31,155
Just about the kind of mass
that we would expect
for a black hole,
1525
01:37:31,190 --> 01:37:34,641
if it really is powering
all the phenomena
that we see in M87.
1526
01:37:36,195 --> 01:37:37,379
The problem is
1527
01:37:37,403 --> 01:37:40,061
that the volume you would
expect for a black hole
1528
01:37:40,095 --> 01:37:46,550
of the mass that we think
the one in M87 has
is very small indeed.
1529
01:37:46,584 --> 01:37:49,563
And so, really,
the problem is to try
1530
01:37:49,587 --> 01:37:52,383
and resolve much smaller
angular distances.
1531
01:37:52,418 --> 01:37:54,834
USTINOV: Small,
angular distances.
1532
01:37:54,869 --> 01:37:57,872
I suppose that's the penny
at a distance of
a mile again.
1533
01:37:59,356 --> 01:38:03,256
In order to try and do this,
I've turned radio astronomer
1534
01:38:03,325 --> 01:38:08,020
and with colleagues used
the radio telescopes
1535
01:38:08,054 --> 01:38:11,747
at Goldstone in California,
1536
01:38:11,782 --> 01:38:15,762
and at Madrid in Spain,
5,000 miles away.
1537
01:38:15,786 --> 01:38:20,377
The object is to try
and get a telescope
as large as the Earth
1538
01:38:20,411 --> 01:38:23,345
by means of which you can
resolve very small distances.
1539
01:38:24,346 --> 01:38:27,108
I'd just like to know,
at this juncture,
1540
01:38:27,142 --> 01:38:31,940
to what extent is all this
a logical consequence
of Einstein's work
1541
01:38:32,009 --> 01:38:34,563
or has it already
taken off on its own?
1542
01:38:36,048 --> 01:38:38,612
Well, it was certainly
not known to Einstein
1543
01:38:38,636 --> 01:38:41,950
that black holes would be
a consequence of his work.
1544
01:38:42,019 --> 01:38:44,090
On the other hand, later work,
1545
01:38:44,125 --> 01:38:48,577
since Einstein died in fact,
has pointed very clearly
1546
01:38:48,612 --> 01:38:49,865
to the fact that
within his theory,
1547
01:38:49,889 --> 01:38:53,272
at least, within
general relativity, one...
1548
01:38:53,306 --> 01:38:55,895
This is a very clear
prediction of the theory.
1549
01:38:57,138 --> 01:39:00,037
And of course,
independent of
the actual nature
1550
01:39:00,072 --> 01:39:02,108
of the underlying object,
we know that it has to
1551
01:39:02,143 --> 01:39:05,387
put out a great deal
of energy because
we see that directly.
1552
01:39:05,422 --> 01:39:10,220
And that implies huge
underlying mass from E=mc2.
1553
01:39:10,254 --> 01:39:15,052
And of course the light
that we get directly
from the object
1554
01:39:15,087 --> 01:39:17,434
as analyzed by
Wallace Sargent...
1555
01:39:17,468 --> 01:39:18,987
Well, they used the
Doppler Effect
1556
01:39:19,056 --> 01:39:22,794
and didn't pose
to us as photons.
1557
01:39:22,818 --> 01:39:24,993
So the richness
of Einstein's ideas
1558
01:39:25,028 --> 01:39:30,550
bears on the entire range
of actual observations
of these objects.
1559
01:39:32,000 --> 01:39:35,486
USTINOV: A computer charted
the fathomless warp of space
1560
01:39:35,521 --> 01:39:39,456
in an imagined collision
between two black holes.
1561
01:39:53,056 --> 01:39:56,921
Our ancestors
frightened themselves
with dragons and hobgoblins,
1562
01:39:56,956 --> 01:40:00,615
we have Jaws and black holes.
1563
01:40:04,826 --> 01:40:06,310
Ow. Ah!
1564
01:40:13,214 --> 01:40:15,871
In fact, at the dead center
of a black hole,
1565
01:40:15,906 --> 01:40:19,082
I found that even
Einstein's ideas falter.
1566
01:40:21,015 --> 01:40:24,156
Here, if general relativity
can now be
1567
01:40:24,190 --> 01:40:26,375
adequately applied to
the black hole itself
1568
01:40:26,399 --> 01:40:29,896
and a certain distance in,
then it's possible to show
1569
01:40:29,920 --> 01:40:33,820
that even the theory itself
predicts its own downfall.
1570
01:40:33,855 --> 01:40:39,343
And this is one of the things
which was not appreciated
before Einstein died.
1571
01:40:39,378 --> 01:40:43,830
Certainly, everything
does get compressed into
a very, very small region.
1572
01:40:43,865 --> 01:40:45,591
And there comes
a point somewhere,
1573
01:40:45,660 --> 01:40:47,041
when new physics has to come in.
1574
01:40:47,075 --> 01:40:49,388
The argument really is
at what point
1575
01:40:49,422 --> 01:40:50,734
and what new physics comes in.
1576
01:40:52,494 --> 01:40:56,429
Of course, when you're
at states of very
high density,
1577
01:40:56,498 --> 01:41:00,330
you can no longer deal with
gravitation in isolation,
1578
01:41:00,364 --> 01:41:02,411
while the other
forces of matter,
1579
01:41:02,435 --> 01:41:06,588
the strong nuclear forces,
the weak forces of
radioactive decay
1580
01:41:06,612 --> 01:41:08,924
and the electromagnetic forces.
1581
01:41:08,959 --> 01:41:13,826
Nor can you stay strictly
within the realm of
classical physics
1582
01:41:13,860 --> 01:41:16,587
and ignore the quantum ideas.
1583
01:41:17,450 --> 01:41:18,831
Yes, you're right.
1584
01:41:18,900 --> 01:41:24,457
It's ironic that Einstein,
who was a founder of
the quantum theory
1585
01:41:24,526 --> 01:41:27,564
through his discovery of
the quantum of the photon,
1586
01:41:27,598 --> 01:41:29,462
which is the particle of light,
1587
01:41:29,531 --> 01:41:32,396
never felt comfortable,
never felt satisfied
1588
01:41:32,431 --> 01:41:35,744
with that theory because of
the element of uncertainty,
1589
01:41:35,779 --> 01:41:39,369
the element of chance
that it brings in
1590
01:41:39,403 --> 01:41:43,994
to a description
of the behavior
of particles.
1591
01:41:44,063 --> 01:41:46,755
USTINOV: Apprehending
more than I could
possibly comprehend,
1592
01:41:46,790 --> 01:41:50,104
I listened like a child
allowed to stay up late
1593
01:41:50,138 --> 01:41:54,073
to ideas that might
surpass Einstein's.
1594
01:41:54,108 --> 01:41:55,971
On a theoretical front here,
I might say that
1595
01:41:56,006 --> 01:42:00,044
[CHUCKLES] it seems to me
we're no closer to knowing
where we're going.
1596
01:42:00,079 --> 01:42:02,495
They are the very
beginnings of efforts
1597
01:42:02,564 --> 01:42:04,991
to make a super gravity theory,
1598
01:42:05,015 --> 01:42:09,468
a quantum theory that
embraces gravity and
the other forces of matter
1599
01:42:09,502 --> 01:42:13,403
that are all unified
together in this great
dream, the grand synthesis
1600
01:42:13,437 --> 01:42:17,786
that Einstein spent 30 years,
the last 30 years of his life
1601
01:42:17,821 --> 01:42:21,100
trying to create and failed.
1602
01:42:21,135 --> 01:42:26,105
That in alone is a measure,
a statement of how difficult
the problem is.
1603
01:42:27,486 --> 01:42:30,696
PENROSE: When you get
down to the size of
an elementary particle,
1604
01:42:30,765 --> 01:42:33,077
the question is,
does the concept
of space and time
1605
01:42:33,112 --> 01:42:35,701
still apply at a
smaller scale than this.
1606
01:42:35,770 --> 01:42:38,773
And I think most physicists
would take the view
1607
01:42:38,807 --> 01:42:41,855
that it does apply
and that it goes on
1608
01:42:41,879 --> 01:42:45,814
until you're down to
a tiny fraction of
the size of a particle.
1609
01:42:45,849 --> 01:42:50,957
But this sort of line
that we're following
is one which suggests
1610
01:42:50,992 --> 01:42:55,030
that perhaps things go wrong
before that and the idea
is that the point,
1611
01:42:55,065 --> 01:42:59,000
the concept of
a point in space is
not the primary concept.
1612
01:42:59,034 --> 01:43:01,554
This is only
a mathematical artifact,
1613
01:43:01,623 --> 01:43:04,050
and that something
a little closer to the idea
1614
01:43:04,074 --> 01:43:06,559
of a particle, although
not actually a particle.
1615
01:43:06,628 --> 01:43:08,389
It's a thing that
we call a twister,
1616
01:43:08,423 --> 01:43:13,542
which is, um...
Well, it's something
I couldn't explain in detail,
1617
01:43:13,566 --> 01:43:17,018
but the idea is that
the concept of a particle
1618
01:43:17,052 --> 01:43:19,203
and of space itself
are both things
1619
01:43:19,227 --> 01:43:22,057
which emerge out of this
more primitive concept.
1620
01:43:22,092 --> 01:43:26,061
And this is the line
we've been pursuing
for many years now.
1621
01:43:26,130 --> 01:43:28,385
And one of the great
problems is to see
1622
01:43:28,409 --> 01:43:34,415
how to tie it in
with general relativity
in a very clear way.
1623
01:43:34,484 --> 01:43:36,589
And there are some
encouraging features,
1624
01:43:36,658 --> 01:43:39,213
but it's certainly
not finished yet.
1625
01:43:41,353 --> 01:43:43,917
USTINOV: From the minutest
quantities of space
1626
01:43:43,941 --> 01:43:46,565
to the immensities
of the universe,
1627
01:43:47,600 --> 01:43:50,431
the director recognized
the little boy in me
1628
01:43:50,465 --> 01:43:53,330
and he let me drive the big
telescope across the sky.
1629
01:43:55,298 --> 01:43:58,197
DIRECTOR: Beautiful, isn't it?
USTINOV: Yes, that's fantastic.
1630
01:43:58,232 --> 01:44:00,682
The rings of Saturn
mapped for me
1631
01:44:00,717 --> 01:44:03,582
the warped space
surrounding the giant planet.
1632
01:44:04,445 --> 01:44:05,756
[BEEPING]
1633
01:44:05,791 --> 01:44:08,897
As I scanned the Milky Way,
Harland Smith reminded me
1634
01:44:08,932 --> 01:44:12,176
that the stars,
billions of them,
and including the sun,
1635
01:44:12,211 --> 01:44:15,870
all circle under
their mutual gravity.
1636
01:44:15,904 --> 01:44:17,872
And we looked beyond
our own galaxy
1637
01:44:17,906 --> 01:44:22,186
to similar whirlpools
of stars far away
in space-time.
1638
01:44:23,774 --> 01:44:26,708
To sample a few of
the billions of galaxies
1639
01:44:26,743 --> 01:44:31,057
prepared me for
contemplating the
whole of Einstein's universe
1640
01:44:31,092 --> 01:44:35,061
and its presumed origin
in the Big Bang.
1641
01:44:35,096 --> 01:44:36,580
And it was brought home to me
1642
01:44:36,615 --> 01:44:39,790
how Einstein's discoveries
about space and time,
1643
01:44:39,825 --> 01:44:45,796
light and matter,
all connect and make
a girdle of the universe.
1644
01:44:48,109 --> 01:44:52,113
Could we pull Einstein's
ideas all together.
1645
01:44:52,147 --> 01:44:56,462
Energy has mass
and mass has energy.
1646
01:44:56,497 --> 01:44:59,500
And the mass of the sun,
so gigantic,
1647
01:44:59,569 --> 01:45:02,296
has only to be burned up
a little at a time
1648
01:45:02,330 --> 01:45:05,747
to provide us with all the
heat and light and power
1649
01:45:05,782 --> 01:45:08,232
that we see here on Earth.
1650
01:45:08,267 --> 01:45:12,306
But that mass has
more gravitational pull
1651
01:45:12,340 --> 01:45:16,068
that pulls light, bends it,
pulls other stars,
1652
01:45:16,965 --> 01:45:21,418
and when stars
start flying apart,
1653
01:45:21,453 --> 01:45:23,672
in the earliest days
of the universe,
1654
01:45:23,696 --> 01:45:28,011
that gravitational pull
slows down their
outward flight.
1655
01:45:30,807 --> 01:45:34,500
The universe
comes into being
out of nothingness.
1656
01:45:37,331 --> 01:45:41,990
Matter, light, energy.
All at once.
1657
01:45:42,025 --> 01:45:44,476
And this matter, this light
and this energy,
1658
01:45:44,510 --> 01:45:47,306
all expand, get more dilute.
1659
01:45:49,619 --> 01:45:54,969
Contract into stars,
galaxies, planets
1660
01:45:55,003 --> 01:45:58,051
and the whole thing
goes on expanding,
1661
01:45:58,075 --> 01:46:00,630
getting bigger, farther apart,
1662
01:46:03,011 --> 01:46:05,887
and that's the phase
we live in now,
1663
01:46:05,911 --> 01:46:09,155
as these galaxies are flying
apart from each other.
1664
01:46:11,088 --> 01:46:15,265
But then comes the moment,
we believe, down the line,
1665
01:46:15,334 --> 01:46:19,649
when they stop flying apart
and their gravitational
attraction
1666
01:46:19,683 --> 01:46:22,755
pulls them back together again.
1667
01:46:22,824 --> 01:46:29,003
The whole thing contracts,
energies go up once more,
1668
01:46:29,037 --> 01:46:33,076
we get to a
gigantic, big crunch.
1669
01:46:43,017 --> 01:46:46,123
In its pristine form,
60 years ago,
1670
01:46:46,192 --> 01:46:49,679
general relativity clearly
required the Big Bang
1671
01:46:49,713 --> 01:46:51,957
for the birth of the universe.
1672
01:46:52,026 --> 01:46:56,824
But that melodramatic story
conflicted with the astronomy
of the day,
1673
01:46:56,893 --> 01:47:02,346
and Einstein doctored
his equations to describe
a more restful universe.
1674
01:47:03,589 --> 01:47:08,525
"In order to arrive
at this consistent view,
1675
01:47:08,560 --> 01:47:11,286
"we admittedly had to
introduce an extension
1676
01:47:11,321 --> 01:47:14,462
"of the field equations
of gravitation,
1677
01:47:14,497 --> 01:47:21,262
"which is not justified by
our actual knowledge
of gravitation."
1678
01:47:21,296 --> 01:47:25,138
"The introduction of
that cosmological term
1679
01:47:25,162 --> 01:47:30,064
"was the biggest
blunder I ever made."
1680
01:47:30,098 --> 01:47:34,551
"Death alone can save one
from making blunders."
1681
01:47:36,795 --> 01:47:42,663
In fairness to Einstein,
just about the time that
he made this remark,
1682
01:47:42,732 --> 01:47:47,115
astronomers' ideas
of the universe were
changing rapidly.
1683
01:47:47,150 --> 01:47:49,428
It was discovered
about that time
that not only
1684
01:47:49,463 --> 01:47:51,672
was there our Milky Way galaxy
1685
01:47:51,706 --> 01:47:55,261
but there were billions
of other galaxies in
the universe as well.
1686
01:47:55,296 --> 01:47:58,437
But more surprisingly,
it was found that they were
1687
01:47:58,472 --> 01:48:02,003
rushing away
from one another
at enormous speeds.
1688
01:48:02,027 --> 01:48:05,444
This was discovered
by means of the Redshift
1689
01:48:05,479 --> 01:48:09,517
that occurs in the
spectrum of the light
due to the Doppler shift
1690
01:48:09,586 --> 01:48:12,865
when things are
moving away from us.Mmm.
1691
01:48:12,900 --> 01:48:17,318
I'm using this particular
machine to measure
the Redshift of the galaxy.
1692
01:48:17,352 --> 01:48:22,496
This is the galaxy and
this is the spectrum
of the galaxy
1693
01:48:22,530 --> 01:48:27,121
under the nearby object
which has no Redshift at all.
1694
01:48:27,155 --> 01:48:30,676
When I change the magnification,
1695
01:48:30,711 --> 01:48:33,897
here is a spectral line
due to sodium.
1696
01:48:33,921 --> 01:48:38,166
And in the distant galaxy,
the spectrum line
is shifted towards the red
1697
01:48:38,201 --> 01:48:41,722
and from the separation
of the two lines,
1698
01:48:41,756 --> 01:48:46,968
one can tell that, roughly,
the Redshift is about
7000 kilometers per second.
1699
01:48:48,211 --> 01:48:50,351
This is one of the most
important kinds of
1700
01:48:50,385 --> 01:48:52,353
measurements that
astronomers make.
1701
01:48:52,387 --> 01:48:55,539
We often make
Redshift measurements.
1702
01:48:55,563 --> 01:48:59,705
It was first discovered
about 50 years ago,
1703
01:48:59,740 --> 01:49:03,675
and this led to the idea
of the expanding universe.
1704
01:49:03,709 --> 01:49:07,920
Later, in 1965,
a radio telescope
in New Jersey
1705
01:49:07,989 --> 01:49:09,553
revealed that
the whole universe,
1706
01:49:09,577 --> 01:49:12,822
even the apparently
empty parts of the sky,
1707
01:49:12,856 --> 01:49:15,376
were aglow with radio emission.
1708
01:49:15,410 --> 01:49:20,070
This is apparently left over
from the birth of
the universe.
1709
01:49:20,105 --> 01:49:25,420
It's this particular
discovery that makes
the Big Bang theory
1710
01:49:25,455 --> 01:49:28,700
the dominant theory
of cosmology at the
present time.
1711
01:49:34,084 --> 01:49:38,226
USTINOV: They represented
the expanding Einsteinian
universe
1712
01:49:38,261 --> 01:49:40,884
by a balloon studded
with galaxies.
1713
01:49:42,196 --> 01:49:43,956
They told me that it
served as a note
1714
01:49:43,991 --> 01:49:48,765
of the entire universe
with its space curving
right back on itself
1715
01:49:48,789 --> 01:49:53,241
because of the gravity
of all its contents.
1716
01:49:53,276 --> 01:49:57,004
And they induced
a cooperative Texan
bug to travel in it.
1717
01:49:59,385 --> 01:50:02,112
In sympathy with
that cosmic bug,
1718
01:50:02,147 --> 01:50:05,288
my mind voyaged
among the galaxies.
1719
01:50:05,357 --> 01:50:07,670
[TRILLING]
1720
01:50:07,739 --> 01:50:13,399
I couldn't really
visualize the overall warping
of cosmic space. Who can?
1721
01:50:13,434 --> 01:50:16,817
But I sensed that gravity
might indeed close up
the universe,
1722
01:50:16,886 --> 01:50:19,785
so that if I traveled
far enough,
1723
01:50:19,820 --> 01:50:24,618
I should find myself
coming full circle
back to my starting point.
1724
01:50:27,241 --> 01:50:32,039
WHEELER: The bug has
nowhere to go but around.
1725
01:50:32,073 --> 01:50:34,006
There's no end.
1726
01:50:34,075 --> 01:50:36,250
Nowhere at end to the universe.
1727
01:50:37,389 --> 01:50:40,634
It's closed universe
1728
01:50:40,668 --> 01:50:42,497
but unbounded universe.
1729
01:50:46,363 --> 01:50:50,609
Einstein's picture was
the universe is closed.
1730
01:50:50,644 --> 01:50:53,267
At least that's what he
wrote in the last edition
1731
01:50:53,301 --> 01:50:58,962
of his book
published in the year
of his death, 1955.
1732
01:50:58,997 --> 01:51:04,841
Today, of course,
we don't really know
how the evidence is.
1733
01:51:04,865 --> 01:51:06,314
Whether there's enough matter
1734
01:51:06,349 --> 01:51:08,903
to curve the universe
up into closure.
1735
01:51:09,973 --> 01:51:14,495
But to predict, as Einstein did,
1736
01:51:14,529 --> 01:51:17,716
the expansion of the universe,
1737
01:51:17,740 --> 01:51:23,055
and to predict it correctly,
and to predict it against
all expectation...
1738
01:51:23,124 --> 01:51:26,818
So fantastic a thing...
To my idea,
1739
01:51:26,852 --> 01:51:30,649
is the greatest prediction
that mankind has ever made.
1740
01:51:30,684 --> 01:51:36,759
And to my mind, gives us
more faith than anything
that we could have,
1741
01:51:36,828 --> 01:51:42,005
that some day we'll find
how the universe itself
came into being.
1742
01:51:42,040 --> 01:51:43,697
[EXPLOSION]
1743
01:51:53,154 --> 01:51:55,501
I think it's quite right to
have celebrated Einstein
1744
01:51:55,536 --> 01:51:58,239
out here on the far
frontier of Texas.
1745
01:51:58,263 --> 01:52:02,899
Because not only is it
the site of a major
observatory...
1746
01:52:02,923 --> 01:52:04,718
And observatories
are going to be
1747
01:52:04,752 --> 01:52:08,594
where Einstein's theories
will have to be tested
in the distant future...
1748
01:52:08,618 --> 01:52:11,725
But also, because we have
all around us still,
1749
01:52:11,759 --> 01:52:14,520
the great frontier,
the American West.
1750
01:52:14,555 --> 01:52:18,939
And this symbolizes, in a way,
Einstein's general relativity
1751
01:52:19,008 --> 01:52:21,079
which is at the far frontier
of the human mind.
1752
01:52:22,632 --> 01:52:29,190
The most beautiful thing
that we can experience
is the mysterious.
1753
01:52:29,225 --> 01:52:34,264
It's the only source of
true art and science.
1754
01:52:34,299 --> 01:52:38,279
And he to whom
this emotion is a stranger,
1755
01:52:38,303 --> 01:52:44,112
he who can no longer
pause in wonder
or stand rapt in awe,
1756
01:52:44,136 --> 01:52:45,897
well, he's already half dead.
1757
01:52:46,621 --> 01:52:47,933
His eyes are shut.
1758
01:52:49,624 --> 01:52:54,077
It was Einstein's passion
to understand the universe.
1759
01:52:54,112 --> 01:52:59,117
For him, that understanding
was the only real power,
1760
01:52:59,151 --> 01:53:02,845
and he did more to create it
than any other man
who's ever lived.
1761
01:53:04,087 --> 01:53:07,125
USTINOV: Well, that's
a very large claim,
1762
01:53:07,159 --> 01:53:10,093
and I'm sure you're right,
but would you agree
with that, Wall?
1763
01:53:10,128 --> 01:53:13,821
Yes. Astronomers use
Einstein's ideas
all the time,
1764
01:53:13,890 --> 01:53:17,204
often without remembering
who thought of them.
1765
01:53:17,273 --> 01:53:21,760
It's the ultimate distinction
in science to be part of
the furniture, like Newton.
1766
01:53:32,150 --> 01:53:35,429
You ask me if
one can eventually express
1767
01:53:35,463 --> 01:53:37,949
everything in scientific terms.
1768
01:53:40,192 --> 01:53:43,230
Yes, it's possible,
but it is useless.
1769
01:53:43,264 --> 01:53:44,517
[CHUCKLES]
1770
01:53:44,541 --> 01:53:47,648
It is as though
one were to reproduce
1771
01:53:47,682 --> 01:53:54,310
Beethoven's Ninth Symphony
in the shape of an
air pressure curve.
1772
01:53:54,344 --> 01:53:56,519
[SCATTERED LAUGHTER]
1773
01:54:02,214 --> 01:54:05,700
I propose a toast
to Albert Einstein.
1774
01:54:05,769 --> 01:54:08,151
One of our greatest heroes.
1775
01:54:08,186 --> 01:54:11,154
Musicians have
Mozart, Beethoven.
1776
01:54:11,189 --> 01:54:14,157
We have Newton and Einstein.
1777
01:54:14,192 --> 01:54:16,090
And it's appropriate
that most of our talk
1778
01:54:16,159 --> 01:54:20,474
has been about his physics,
but we shouldn't forget
the other side,
1779
01:54:20,508 --> 01:54:23,384
Albert Einstein the folk hero.
1780
01:54:23,408 --> 01:54:27,239
Though widely honored,
he was a simple man
who spurned
1781
01:54:27,308 --> 01:54:32,486
and shunned wealth,
power and status.
1782
01:54:32,520 --> 01:54:35,213
A refugee on the
run from Hitler,
1783
01:54:35,247 --> 01:54:39,734
he was a dignified
and gentle symbol
1784
01:54:39,769 --> 01:54:43,359
of scientific inspiration
that was a great
1785
01:54:43,393 --> 01:54:46,258
particular inspiration
for young refugees
1786
01:54:46,327 --> 01:54:48,743
and immigrants
interested in science.
1787
01:54:48,778 --> 01:54:52,437
The reputed grandfather
of the atom bomb,
1788
01:54:52,506 --> 01:54:56,268
he was the moral leader
of the efforts
1789
01:54:56,303 --> 01:55:03,103
to bring that dangerous and
deadly application of E=mc2
under international control.
1790
01:55:03,172 --> 01:55:06,451
I propose a toast
to the memory of
Albert Einstein.
1791
01:55:06,520 --> 01:55:10,593
ALL: Hear, Hear.
To Albert Einstein.
1792
01:55:16,461 --> 01:55:21,776
USTINOV: The most daring
proposition in relativity
is that the laws of nature
1793
01:55:21,811 --> 01:55:26,274
must remain the same
at all places and
at all times,
1794
01:55:26,298 --> 01:55:29,646
even in galaxies so far away
1795
01:55:29,681 --> 01:55:35,583
that their light has traveled
for thousands of millions
of years to reach us.
1796
01:55:35,618 --> 01:55:39,622
If so, Albert Einstein's
own laws of nature,
1797
01:55:39,656 --> 01:55:43,626
conceived with pen and
paper on the planet Earth,
1798
01:55:44,316 --> 01:55:46,940
hold good everywhere.
1799
01:55:52,531 --> 01:55:57,398
[AS EINSTEIN] "What really
interests me is whether
God had any choice"
1800
01:55:57,433 --> 01:56:00,643
"in the creation
of the world."
147096
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