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A BRIEF HISTORY OF TIME
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Which came first?
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The chicken or the egg?
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Did the Universe have a beginning?
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And if so, what happened before then?
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Where does the Universe come from?
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And where is it going?
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Luck.
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Luck, well
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We have been very lucky.
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I mean, my family, and
Stephen, everybody
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We had a few disasters, but
the point is that we have survived
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Everybody has disasters, and yet
some people disappears
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and they're never seen again.
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Flybombs were very alarming
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Seeking, buzzing over,
and then they would cut out.
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And when you heard the bang,
you knew it wasn't you,
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so you went back to your meal,
or whatever.
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But one did fall quite close to
our house.
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and it blew the back windows out
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so the glass was sticking dagger points
out of the opposite wall.
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When Stephen was born,
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we decided he'd better
be born in Oxford.
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So while I was staying
in the hospital.
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I went to Blackwells,
in Oxford,
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and I bought
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an astronomical atlas.
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One of my sisters-in-law
said:
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"This is a very prophetic thing
for you to have done."
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How real is time?
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Will it ever come to an end?
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Where does the difference between
the past and the future come from?
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Why do we remember the past
but not the future?
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I can remember that day when
we travelled through London
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and the black-out was over.
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And the trains, instead
of being shut in
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by blinds, so you just
travelled in a train.
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We were coming over
one of the bridges
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and all lights, well, such lights
as were left
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were only in London.
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but it was also a completely
starry night
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You could see the might whole
against it.
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I remember we all used to lie
on the grass,
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looking staight up through a telescope
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and seeing the wonders of the stars.
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Stephen always had a strong
sense of wonder
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and I could see that the stars would
draw him,
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and further than the stars.
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I was born exactly 300 years
after the death of Galileo.
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I estimate that about 200 000
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other babies were also
born that day.
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I don't know whether any of them
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was later interested
in astronomy.
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My first memory is about
pushing a rather antiquated
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carriage built[?] pram
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along North Road,
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with Stephen and Mary in it, sort of
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looking very large, because they had
large heads
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and pink cheeks, and they were
very noticeable.
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They all looked diffrent from
ordinary people.
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I can remember visiting the
Hawking home
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several times.
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It was the sort of place where,
if you were invited to stay to supper,
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you might be allowed to have
your conversation with Stephen...
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but the rest of the family would be
sitting at the table reading a book.
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A behaviour which is not really approved
over my circle,
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but which is tolereated from the
Hawkings because they were recognised to be
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very excentric,
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highly intelligent, very clever
people,
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but still... a bit... odd.
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My impression of the Hawking family
was that they were all like that,
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except for Stephen,
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who seemed to be the only
normal member of the family.
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Stephen used to reckon he knew,
I think it was,
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11 ways of getting into the
house.
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But I could only find 10 of them.
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I'm not sure what the other way was.
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On the north side of the house was
bicycle shad
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had a door at the front and a door
at the back.
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Above that,
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there was a window into the
L-shaped room.
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And at the front you could
get sort of round corner
onto the roof
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And from that level you could get
onto the main roof.
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I think one of the ways that Stephen
could get in was
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on the main roof.
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I must say he was a much better
climber than I was.
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I still don't know what
the 11th one was!
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Before the 20th century,
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it was thought that the Universe
had existed forever,
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or had been created at some time
in the past
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more or less as we observe it
today.
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People found comfort
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in the thought that even though
they may grow older and die,
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the Universe was eternal and unchanging.
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I gave up playing games
with Stephen
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when he was ill that time about...
when he was about 12.
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Becouse he started taking games terribly
seriously.
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We had Monopoly.
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And...
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first of all the Monoply board
sprang
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railways going across it...
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tried to add complications.
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And then Monopoly just wasn't
adaptable enough.
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But he ended up with a fearful game
called 'Dynasty'
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which, as far as I can make out,
for I say, I never played it,
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went on forever, because there
was no way of ending it!
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It was almost a substitute for
living as far as I could make out,
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It took hours, and hours,
and hours.
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I thought it was a perfectly terrible game.
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I couldn't imagine anyone getting
taken up with that.
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But Stephen always had a very
complicated mind,
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and I felt as much as anything
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it was the complication of it
that appealed to him.
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When I was in high school,
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I learned that light from distant
galaxies
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was shifted at the red.
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This meant that they were
moving away from us
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and that the Universe
was expanding.
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But I didn't believe it.
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A static Universe seemed
much more natural.
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It could have existed, and could
continue to exist forever.
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We were discussing the possibility
of the spontaneous generation of life,
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and I think that Stephen
made a remark
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which indicated not only that he
thought of this, but he did even also
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come across some calculations
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as to how long it might take.
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At that time I think I made a commen
to one of my friends, John McLennahan:
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"I think that Stephen will turn out
to be unusually capable."
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I didn't [say it] in quite
these words
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but I made one such remark to him
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and he disagreed.
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And so we made a bet on the subject.
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In a childish way we bet
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a bag of sweets on the issue.
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And instantly I reckon that my
bet has come correct
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and I think I'm entitled to payment
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which is not yet been made.
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The expansion of the Universe
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suggested a possibility
that the Universe had a beginning
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at some time in the past.
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The point at which the Universe
may have started out
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became known as the Big Bang.
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The first year he was at
St. Albans school,
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he came, I think, third
from the bottom.
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So I said: "Well, Stephen,
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"do you really have to be as
far down as that?"
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And he said: "Well,"
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"lot of other people didn't do
much better."
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He was quite unconcerned.
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Somehow he was always recognized
as being very bright
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and in fact they gave him
the Divinity Prize one year.
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That was not surprising as his father
used to reach him Bible stories
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from very early age
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and he knew them all very well
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and he was quite well versed in religious
things although
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I don't think he makes a very great
deal of practice of it now.
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Everyone used to argue theology.
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That's a good safe subject.
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You don't need any fact, sort of,
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or distracting things like that.
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If you're going for arguing,
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you know, debating, you can quite
happily debate about anything...
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including...
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theology and the existence of,
or otherwise, of God.
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And then someone gets bored, or
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Journey Into Space comes on
or something like that
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the argument breaks up.
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In an unhcnaging Universe,
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one can imagine that God
created the Universe
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at literally any time
in the past.
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On the other hand, if the Universe
is expanding
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there are maybe physical
reasons
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why there had to be a beginning.
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An expanding Universe does not
preclude a creator...
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but it does place limits on when
he might have carried out his job.
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When the family went to India,
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it was arranged that Stephen to
come and live with us for a year.
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He decided it would
be nice that he should have
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Scottish dancing in the evening.
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Now mind you, this was quite an
ordinary house,
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but we had rather a lot of room
and a large hall,
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and so we bought
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some records, and
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a book about what to do,
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and Stephen took charge.
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And he insisted to put on a jacket
and a tie.
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And then he was the master
of the proceedings.
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And Stephen took it very
seriously
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But then he liked dancing, you see.
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There were 4 physicists in my year.
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Gordon Berry,
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Richard Bryath,
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Stephen
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myself.
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I first remember Stephen
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on the occasion when Gordon and I
went up after dinner to his room,
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to try to find him.
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And Stephen was up there
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with a crate of beer,
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slowly drinking his way through it.
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He was only 17,
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he couldn't legally go into a pub.
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He did come at Oxford ridiculously
early.
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We used to have what we called
a "gathering net".
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We used to organize that at beer
parties and various things like that
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to gather under this cover as many
freshman as we could get, you see
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get them to join the boat club.
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And that's how we collected
him, you see.
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But the question, always,
with Stephen, was
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"Should we make him the cox
of the first 8,"
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"or the second 8?", you see?
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Well, coxes can be adventurous.
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00:15:55,660 --> 00:15:59,280
But some coxes can be very steady
people, you see.
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He was rather an adventurous type.
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You never knew could what he was going to do
when he went out with the crew.
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I think he used to bring his work there
with him into the boat sometimes
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Some thinking here was going on...
Different levels.
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We were asked to read a chapter,
chapter 10
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in a book about
electricity and magntism
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00:16:32,527 --> 00:16:34,017
by Bleaney & Bleaney,
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00:16:34,142 --> 00:16:36,773
an unlikely combination of a
husband and wife team.
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And at the end of that chapter there
were 13 questions,
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all of them final honours questions.
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I discovered very rapidly that I
couldn't do any of them.
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Richard and I worked together
for the week,
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and we managed to do one a half
questions,
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which we felt very proud of.
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Gordon refused all assistance
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and managed to do one all by
himself.
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Stephen, as always, hadn't even
started.
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But the next morning, he went up to his
rooms at 9 o'clock,
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and we came back about 12, maybe
five past 12,
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and down came Stephen, we were in the
college gateway, the lodge,
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"Ah, Hawking," I said, "how many
have you managed to do then?"
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"Well," he said:
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"I've only had time to the first 10."
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I think at that point we realised
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that it's not just we weren't
in the same street,
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we weren't on the same planet.
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I once calculated that I did
about 1 000 hours work
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in the 3 years I was at Oxford.
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An average of one hour a day.
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I'm not proud of this lack of work.
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I'm just describing my
attitude at the time.
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An attitude that nothing
was worth making an effort for.
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He used to produce his work
every week for tutorial
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and, as he never kept any notes,
or papers or that sort of things,
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on leaving my room he would normally
throw it in my wastepaper basket.
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And when he was with other
undergraduates at the tutorial
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00:18:22,643 --> 00:18:24,467
and they saw this happen
251
00:18:24,593 --> 00:18:27,062
they were absolutely horrified, 'cause
they thought
252
00:18:27,187 --> 00:18:30,328
he did this work in probably half
an hour,
253
00:18:30,453 --> 00:18:32,517
if they could have done it in a year
254
00:18:32,642 --> 00:18:36,554
they wouldn't have thrown it in the
wastepaper basket, they would have
put in a frame up on their walls.
255
00:18:38,313 --> 00:18:40,472
Because of my lack of work,
256
00:18:40,597 --> 00:18:43,713
I had planned to get through
the final exam
257
00:18:43,838 --> 00:18:46,981
by doing problems in
Theoretical Physics,
258
00:18:47,252 --> 00:18:52,182
and avoiding any questions that
required factual knowledge.
259
00:18:53,673 --> 00:18:56,115
I didn't do very well.
260
00:18:57,493 --> 00:19:01,835
I was on the borderline between a
first and a second class degree.
261
00:19:02,321 --> 00:19:06,792
And I had to be interviewed
to determine which I should get.
262
00:19:08,345 --> 00:19:11,739
They asked me about my
future plans.
263
00:19:12,907 --> 00:19:14,299
I replied
264
00:19:14,571 --> 00:19:18,762
if they gave me a first,
I would go to Cambridge;
265
00:19:20,136 --> 00:19:22,451
if only got a second,
266
00:19:22,576 --> 00:19:24,889
I would stay in Oxford.
267
00:19:26,640 --> 00:19:29,444
They gave me a first.
268
00:19:35,548 --> 00:19:38,831
I drove Stephen and his
young brother
269
00:19:38,956 --> 00:19:41,023
at Woburn Park.
270
00:19:41,792 --> 00:19:46,088
And he climbed a tree; he was testing
himself out, I think, I didn't realize.
271
00:19:46,371 --> 00:19:49,915
And he did manage to climb the tree,
and to go along a branch of it
272
00:19:50,041 --> 00:19:51,595
and to get himself down.
273
00:19:52,442 --> 00:19:55,841
I think he began to notice that his hands
274
00:19:55,966 --> 00:19:58,141
were less useful than they had been,
275
00:19:58,266 --> 00:20:00,183
but he didn't tell us.
276
00:20:02,456 --> 00:20:04,941
Uni has this square staircases
277
00:20:05,252 --> 00:20:07,436
which are round but they're
square.
278
00:20:08,248 --> 00:20:10,984
He was just coming down from
one of the rooms
279
00:20:11,109 --> 00:20:13,070
Steve actually fell on the stairs
280
00:20:13,195 --> 00:20:16,986
coming down the stairs and, he kind of
bounced all the way down to the bottom.
281
00:20:17,956 --> 00:20:20,068
I don't know if he loss conciousness,
282
00:20:20,193 --> 00:20:22,491
but he lost his memory.
283
00:20:23,761 --> 00:20:27,329
We took him to either my room
or someone's room.
284
00:20:27,600 --> 00:20:29,916
The first question of course was:
"Who am I?"
285
00:20:30,041 --> 00:20:32,291
and we told him: "You're
Steve Hawking."
286
00:20:32,466 --> 00:20:35,166
and a minute later
or right away
287
00:20:35,291 --> 00:20:37,255
He would ask: "Who am I?"
288
00:20:37,381 --> 00:20:38,755
"Euh.. Steve Hawking."
289
00:20:38,880 --> 00:20:42,798
And then after a couple of minutes
he remembered he was Steve Hawking.
290
00:20:43,648 --> 00:20:47,225
and we tell him: "Do you remember
going down to the bar and having a drink"
291
00:20:47,350 --> 00:20:48,649
"on Sunday night?"
292
00:20:48,774 --> 00:20:52,228
Or: "Do you remember rowing,
coxing on the river on Monday?"
293
00:20:52,499 --> 00:20:56,731
And his memory came back
gradually, until he could remember
the previous days events
294
00:20:56,856 --> 00:20:58,325
and then the previous hour.
295
00:20:58,450 --> 00:21:01,617
By the end of the 2 hours
he could remember everything.
296
00:21:02,593 --> 00:21:06,993
The question was: "Well maybe,
you know, you lost some of your mind
bacause of this"
297
00:21:07,445 --> 00:21:11,315
And so, Steve decided: "Well, I'll take
the Mensa test."
298
00:21:11,440 --> 00:21:13,374
We said: "Of course you'll get
into Mensa."
299
00:21:13,645 --> 00:21:15,573
But he came back delighted
300
00:21:15,698 --> 00:21:19,870
that he was able to get into Mensa,
absolutely delighted.
301
00:21:30,252 --> 00:21:34,338
I felt that there were 2 areas
of Theoretical Physics
302
00:21:34,463 --> 00:21:36,855
I might study at Cambridge
303
00:21:38,969 --> 00:21:43,393
One was Cosmology, the study of
the very large.
304
00:21:47,032 --> 00:21:49,907
the other was Elementary Particles,
305
00:21:50,032 --> 00:21:52,598
the study of the very small.
306
00:21:54,345 --> 00:21:57,424
However, I thought that
elementary particles
307
00:21:57,549 --> 00:21:59,171
were less attractive
308
00:21:59,296 --> 00:22:02,295
because there was no proper
theory.
309
00:22:03,414 --> 00:22:08,066
All they could do was arrange the
particles in families,
310
00:22:08,393 --> 00:22:10,150
like in botany.
311
00:22:13,100 --> 00:22:18,684
In Cosmology, on the other hand,
there was a well defined theory:
312
00:22:18,809 --> 00:22:22,298
Einstein's General Theory of
Relativity.
313
00:22:29,187 --> 00:22:31,795
It was very a very cold year
314
00:22:33,766 --> 00:22:40,014
and the ice on Veralamian pond
was, it was all frozen then.
315
00:22:40,547 --> 00:22:43,042
and we all went skating.
316
00:22:43,964 --> 00:22:46,675
And Stephen managed to skate
fairly well.
317
00:22:46,800 --> 00:22:49,480
But then, he and I were closed
together,
318
00:22:49,606 --> 00:22:53,482
he wasn't skating in a very advanced
way, but nor was I as it comes to,
319
00:22:53,607 --> 00:22:55,781
and he fell
320
00:22:56,197 --> 00:22:58,150
and he couldn't get up.
321
00:22:59,606 --> 00:23:03,270
So I took him to café to warm up
322
00:23:03,395 --> 00:23:06,235
and he told me then all about it
323
00:23:07,295 --> 00:23:10,116
and it was diagnosed.
324
00:23:11,343 --> 00:23:14,113
I've insisted on going to see his doctor
325
00:23:14,238 --> 00:23:17,621
because, it seemed to me,
however long you're going to live
326
00:23:17,747 --> 00:23:20,026
there's probably something
someone can do about it.
327
00:23:20,151 --> 00:23:22,824
at least anyhow to make things
easier for people.
328
00:23:23,165 --> 00:23:25,560
And, I won't mention the doctor's name,
329
00:23:25,686 --> 00:23:29,013
but I got to see him at the
London Clinic.
330
00:23:29,509 --> 00:23:32,779
And he was rather surprised that I should
bother to come down to see him.
331
00:23:32,904 --> 00:23:35,139
I mean afer all I was only
Stephen's mother!
332
00:23:35,264 --> 00:23:39,979
He was quite nice, I mean, he agreed
to see me in a rather grand way.
333
00:23:40,104 --> 00:23:42,338
And he said: "Yes, it's all
very sad, I mean,
334
00:23:42,463 --> 00:23:45,358
a brilliant young man, cut off in
the prime of his."
335
00:23:45,530 --> 00:23:47,949
But of course I said:
"What can we do?"
336
00:23:48,074 --> 00:23:52,019
"What can we do to, sort of...
Can we give him... can we get
physiotherapy?"
337
00:23:52,144 --> 00:23:55,571
"Can we get anything like that
that will help in any way?"
338
00:23:55,696 --> 00:23:57,707
He said: "Well, actually no,"
339
00:23:57,833 --> 00:24:00,788
"there's nothing to it", more or less.
That's it.
340
00:24:04,366 --> 00:24:07,631
Shortly after my 21st
birthday,
341
00:24:07,756 --> 00:24:10,727
I went into hospital for
tests.
342
00:24:12,930 --> 00:24:15,626
They took a muscle sample from
my arm,
343
00:24:15,751 --> 00:24:18,016
stuck electrodes into me,
344
00:24:18,187 --> 00:24:21,808
and injected some radio-opaque fluid
into my spine
345
00:24:22,024 --> 00:24:25,133
and watched it going up and down with
X-rays
346
00:24:25,258 --> 00:24:27,476
as they tilted the bed.
347
00:24:29,376 --> 00:24:32,641
I was diagnosed as having ALS
348
00:24:32,766 --> 00:24:35,783
Amyotrophic lateral sclerosis...
349
00:24:35,954 --> 00:24:40,340
or motor-neuron disease,
as it is also known.
350
00:24:42,002 --> 00:24:44,330
The doctors offered no cure
351
00:24:44,455 --> 00:24:47,799
and gave me 2 and a half years
to live.
352
00:24:58,577 --> 00:25:00,884
I went into the graduates common
room and
353
00:25:01,009 --> 00:25:04,100
looking really for someone to have
lunch with
354
00:25:04,226 --> 00:25:07,176
and there was nobody around that
I particularly wished to have lunch
with
355
00:25:07,301 --> 00:25:09,315
and then learned about Stephen
walk through the door.
356
00:25:09,487 --> 00:25:12,807
don't know what he was doing in
Oxford either, I've certainly forgotten that.
357
00:25:12,932 --> 00:25:14,422
And so...
358
00:25:15,132 --> 00:25:18,489
Stephen generously went off
to buy the drinks
359
00:25:18,615 --> 00:25:21,468
and brought them over, put them
down on the table,
360
00:25:21,594 --> 00:25:25,268
and as he put his pint of beer
down, he spewed it.
361
00:25:25,610 --> 00:25:27,881
And I sort of said, genially:
362
00:25:28,006 --> 00:25:31,291
"Ah, haven't you been drinking
at this time of day?"
363
00:25:31,416 --> 00:25:35,635
and he then told me that he'd been
in Edinburgh for 3 weeks
364
00:25:35,983 --> 00:25:39,488
and they'd done a whole series
of tests
365
00:25:39,785 --> 00:25:42,874
and they decided what was wrong
with him.
366
00:25:43,202 --> 00:25:46,832
And he told me very straight and
flat
367
00:25:47,257 --> 00:25:52,360
that he was gradually going to
lose the use of all of his body.
368
00:25:52,485 --> 00:25:55,049
And that eventually
369
00:25:55,174 --> 00:25:59,874
only his heart and his lungs would
still be operating,
370
00:26:00,226 --> 00:26:01,779
and his brain.
371
00:26:02,081 --> 00:26:05,328
And that they told him that,
372
00:26:05,453 --> 00:26:08,507
eventually, he would essentially have
the body of a cabbage.
373
00:26:08,632 --> 00:26:11,963
but his mind would still be
in perfect working order,
374
00:26:12,131 --> 00:26:15,753
and he would be unable to communicate
with the rest of the world.
375
00:26:18,853 --> 00:26:22,951
My dreams at that time
were rather disturbed.
376
00:26:24,159 --> 00:26:27,281
Before my condition had
been diagnosed,
377
00:26:27,406 --> 00:26:30,209
I had been very bored with life.
378
00:26:31,636 --> 00:26:35,620
There had not seemed to be
anything worth doing.
379
00:26:37,437 --> 00:26:40,578
But shortly after I came
out of hospital,
380
00:26:40,703 --> 00:26:44,578
I dreamt that I was going
to be executed.
381
00:26:45,345 --> 00:26:48,832
I suddenly realized that there
were lots of worthwile things
382
00:26:48,957 --> 00:26:50,350
I could do
383
00:26:50,475 --> 00:26:52,254
if I were retrieved.
384
00:26:59,149 --> 00:27:02,049
I knew perfectly well
that he had no faith.
385
00:27:03,097 --> 00:27:08,467
And to me that made it more difficult,
386
00:27:08,645 --> 00:27:12,667
because you must ask yourself:
"Why me? Why this?"
387
00:27:12,792 --> 00:27:14,353
"Why now?"
388
00:27:14,478 --> 00:27:16,761
But he just totally,
389
00:27:16,886 --> 00:27:18,234
flatly, accepted
390
00:27:18,359 --> 00:27:20,854
that this was what was going
to happen to him.
391
00:27:20,979 --> 00:27:25,237
And as far as I can gather at that
point he started to do some work.
392
00:27:27,007 --> 00:27:32,116
At first, there di not seem to be
much time in working at my research,
393
00:27:32,293 --> 00:27:35,331
because I didn't expect to live long
enough
394
00:27:35,457 --> 00:27:37,951
to finish my Ph.D.
395
00:27:39,300 --> 00:27:41,924
However, as time went by,
396
00:27:42,050 --> 00:27:44,808
the disease seemed to
slow down.
397
00:27:46,337 --> 00:27:49,709
I began to understand
General Relativity
398
00:27:49,834 --> 00:27:52,761
and make progress with my work.
399
00:27:54,309 --> 00:27:56,899
But what really made a difference
was
400
00:27:57,025 --> 00:28:00,899
I got engaged to a girl called
Jane Wilde.
401
00:28:02,759 --> 00:28:05,750
This gave me something
to live for,
402
00:28:05,875 --> 00:28:08,802
but it also meant that I had
to get a job
403
00:28:08,927 --> 00:28:11,325
if we were to get married.
404
00:28:13,514 --> 00:28:16,311
Stephen was already ill,
Jane knew it.
405
00:28:16,631 --> 00:28:19,914
And it was another instance of
Stephen's luck.
406
00:28:20,039 --> 00:28:23,544
Meeting the right person at the
right time,
407
00:28:23,669 --> 00:28:25,367
because Jane...
408
00:28:25,492 --> 00:28:28,760
Stephen was very very badly depressed.
409
00:28:28,885 --> 00:28:30,772
And...
410
00:28:30,897 --> 00:28:33,262
he wasn't really very much inclined to
go on with his work, I mean,
411
00:28:33,387 --> 00:28:36,595
you're told you got 2 and a half years,
what can you do in that time?
412
00:28:36,721 --> 00:28:41,104
But meeting Jane, really put him
on his metal,
413
00:28:41,229 --> 00:28:43,105
And he started to work.
414
00:28:45,596 --> 00:28:50,035
I wanted to understand
how the Universe began.
415
00:28:52,063 --> 00:28:55,078
Einstein's theory of General
Relativity
416
00:28:55,203 --> 00:28:58,847
showed that the Universe was
expanding.
417
00:28:59,625 --> 00:29:03,170
But there was no answer to the
crucial question:
418
00:29:03,296 --> 00:29:05,599
"Must there have been a Big Bang?"
419
00:29:05,936 --> 00:29:08,639
"A beginning to time?"
420
00:29:09,849 --> 00:29:12,848
Then, in my 3rd year at Cambridge
421
00:29:13,183 --> 00:29:18,723
Roger Penrose made his
discovery about the death of stars.
422
00:29:20,770 --> 00:29:23,858
I remember talking to this
friend, Ivor Robinson,
423
00:29:23,983 --> 00:29:27,044
and we were having some very
animated conversation.
424
00:29:27,363 --> 00:29:30,824
and then we had to cross the road,
425
00:29:30,992 --> 00:29:38,708
and as we crossed the road of course
the conversation stopped, and then
we got to the other side, well evidently
I had some idea in crossing the road
426
00:29:38,833 --> 00:29:40,544
but then the conversation started up
427
00:29:40,670 --> 00:29:42,697
and it got completely blotted
out of my mind.
428
00:29:42,822 --> 00:29:46,929
And it was only later, after my
friends had gone home.
429
00:29:47,054 --> 00:29:49,360
and I began
430
00:29:49,485 --> 00:29:53,677
having this strange feeling
of [?]elation, it feeling wonderful.
431
00:29:53,802 --> 00:29:57,415
And I couldn't figure out why on earth
I should feel like that,
432
00:29:57,540 --> 00:30:01,179
so I went back over the day, thinking all possible things
which might have contributed to such a feeling,
433
00:30:01,355 --> 00:30:03,814
and then gradually I unearthed
434
00:30:03,939 --> 00:30:06,436
this thought which I had while
crossing the street.
435
00:30:07,028 --> 00:30:09,697
Penrose announced this
result, that
436
00:30:09,822 --> 00:30:12,291
when stars collapse indefinetly
437
00:30:12,416 --> 00:30:14,526
they will become singular
438
00:30:14,702 --> 00:30:18,276
as long as certain very broad
conditions are satisfied
439
00:30:18,401 --> 00:30:20,708
that every body would have
regarded as reasonable.
440
00:30:20,976 --> 00:30:23,323
and I remember Stephen Hawking,
441
00:30:23,448 --> 00:30:26,393
who was then approaching his
3rd year as a research student, saying:
442
00:30:26,518 --> 00:30:28,584
"What, very interesting results,"
443
00:30:28,709 --> 00:30:30,913
"I wonder wehter they could be adapted"
444
00:30:31,039 --> 00:30:33,522
"to understand the origin of the Universe."
445
00:30:33,919 --> 00:30:35,866
and what he had in mind, you see,
446
00:30:35,991 --> 00:30:39,569
was that if, just mentally,
you reverse the sense of time,
447
00:30:39,694 --> 00:30:41,809
you can think of the expanding universe
448
00:30:41,935 --> 00:30:46,142
as a collapsing system, it's a bit like a giant,
a very giant star collapsing
449
00:30:47,174 --> 00:30:50,652
Roger Penrose proved
that a dying star
450
00:30:50,778 --> 00:30:53,501
collapsing under its own gravity
451
00:30:53,626 --> 00:30:56,873
eventually shrinks to a singluarity,
452
00:30:57,757 --> 00:31:01,715
a point of infinite density
and zero size.
453
00:31:04,128 --> 00:31:08,203
I realized that if I reversed
the direction of time,
454
00:31:08,593 --> 00:31:11,823
so that the collapse
become an expansion,
455
00:31:12,117 --> 00:31:13,877
I could prove
456
00:31:14,148 --> 00:31:16,540
that the Universe had a beginning.
457
00:31:19,646 --> 00:31:21,417
But my proof,
458
00:31:21,542 --> 00:31:25,180
based on Einstein's theory
of General Relativity,
459
00:31:25,517 --> 00:31:28,892
also showed that
we cannot understand
460
00:31:29,163 --> 00:31:31,293
how the universe began,
461
00:31:32,163 --> 00:31:36,444
because it showed
that all scientific theories,
462
00:31:36,569 --> 00:31:39,958
incuding General Relativity itself,
463
00:31:40,083 --> 00:31:43,619
break down
at the beginning of the Universe.
464
00:31:55,504 --> 00:32:00,323
We had this meeting at the Institute
of Space Physics in New York.
465
00:32:00,902 --> 00:32:03,689
I said: "Before we reach
a final conclusion,"
466
00:32:03,815 --> 00:32:06,248
"we ough to throw into the pot"
467
00:32:06,373 --> 00:32:08,135
"still another object:"
468
00:32:08,261 --> 00:32:12,359
"a gravitationally completely
collapsed object."
469
00:32:13,166 --> 00:32:15,066
Well, after you've used the phrase:
470
00:32:15,191 --> 00:32:18,527
"a gravitationally completely
collapsed object"
471
00:32:18,652 --> 00:32:19,973
ten times,
472
00:32:20,098 --> 00:32:23,021
you conclude you've get to get
a better name,
473
00:32:23,146 --> 00:32:27,783
so that's when I switched
to the word 'black hole'.
474
00:32:28,416 --> 00:32:31,655
The word 'black hole', which
John Miller coined, suddenly caught on.
475
00:32:31,780 --> 00:32:33,963
Everybody adopted it
476
00:32:34,088 --> 00:32:37,530
and from then on people around the world,
in Moscow,
477
00:32:38,801 --> 00:32:42,307
in America, in England and elsewhere,
478
00:32:42,432 --> 00:32:45,641
could know they were speaking
about the same thing.
479
00:32:45,766 --> 00:32:50,042
And not only that, but suddenly
the hole range of concept's
480
00:32:50,167 --> 00:32:53,615
got throught to the general public,
and even science fiction writers
481
00:32:53,740 --> 00:32:56,811
all of a sudden could talk about it.
482
00:32:58,242 --> 00:33:00,194
Tonight, my friends,
483
00:33:00,868 --> 00:33:06,535
We stand on the break
of a feat unparalleled in space exploration.
484
00:33:07,827 --> 00:33:12,574
If the data in my returning probe ship
matches my computerized calculations,
485
00:33:12,700 --> 00:33:16,467
I will travel where no man
has dared to go.
486
00:33:17,464 --> 00:33:19,327
Into the black hole?
487
00:33:19,893 --> 00:33:21,171
In...
488
00:33:22,635 --> 00:33:24,046
Through...
489
00:33:25,417 --> 00:33:26,978
And behind!
490
00:33:29,232 --> 00:33:30,963
Why that's crazy!
491
00:33:32,260 --> 00:33:33,857
Ah! Impossible!
492
00:33:36,608 --> 00:33:39,104
As a massive star contracts,
493
00:33:39,230 --> 00:33:41,627
its gravity becomes so strong
494
00:33:41,752 --> 00:33:44,767
that light can no longer escape.
495
00:33:46,492 --> 00:33:49,879
The region from which
nothing can escape
496
00:33:50,004 --> 00:33:52,043
is called a 'black hole'
497
00:33:52,168 --> 00:33:55,789
and its boundary is called
the 'event horizon'.
498
00:33:58,325 --> 00:34:00,986
One might say
of the event horixon
49/
499
00:34:01,111 --> 00:34:04,085
what Dante said
of the entrance to Hell:
500
00:34:05,669 --> 00:34:09,245
"Abandon all hope
ye who eneter here."
501
00:34:14,199 --> 00:34:18,034
I was once asked
to actually be an adjudicator
502
00:34:18,691 --> 00:34:22,577
on an essay of which
the subject was:
503
00:34:22,702 --> 00:34:25,435
"How to fall into a black hole
and live"
504
00:34:25,560 --> 00:34:27,440
Now, the problem I had was
505
00:34:27,565 --> 00:34:30,490
that I wouldn't know how
to give out the prize,
506
00:34:30,615 --> 00:34:34,243
because if I said: "Well, that
looks like a really good essay",
507
00:34:34,368 --> 00:34:37,513
the only real way
of showing that this was right
508
00:34:37,638 --> 00:34:41,172
was to actually follow it,
to do the experiment of fall in,
509
00:34:41,298 --> 00:34:44,197
but then having fallen in,
510
00:34:44,322 --> 00:34:46,860
also I would assume
taking the person who wrote the essay with you,
511
00:34:46,985 --> 00:34:49,845
the question would be:
"How do you tell the rest of the world?"
512
00:34:50,012 --> 00:34:52,654
Do you take the prize in with you
513
00:34:52,780 --> 00:34:55,677
that you'd give to him, and what
do they do with it when do when get to the center?
514
00:34:56,544 --> 00:34:58,106
Beleive me
515
00:34:58,798 --> 00:35:01,975
I've benn waiting a long time
for someone like you
516
00:35:02,246 --> 00:35:03,734
to record this moment.
517
00:35:03,859 --> 00:35:05,270
Thank you, doctor.
518
00:35:06,694 --> 00:35:08,256
Then, I'm ready.
519
00:35:09,800 --> 00:35:11,484
Ready to embark
520
00:35:11,755 --> 00:35:13,732
on man's greatest journey.
521
00:35:13,911 --> 00:35:15,600
Certainly his riskiest.
522
00:35:16,540 --> 00:35:18,996
The risk is incidental
523
00:35:19,121 --> 00:35:21,202
compared to the possibility to possess
524
00:35:21,473 --> 00:35:23,420
the great truth of the unknown.
525
00:35:23,545 --> 00:35:24,461
There,
526
00:35:25,528 --> 00:35:30,417
long cherished laws of nature
simply do not apply.
527
00:35:30,978 --> 00:35:32,713
They vanish.
528
00:35:33,701 --> 00:35:35,925
And life?
529
00:35:37,356 --> 00:35:38,687
Life?
530
00:35:41,604 --> 00:35:43,724
Life forever.
531
00:36:08,387 --> 00:36:10,818
If you were watching
an anoustronaut
532
00:36:10,943 --> 00:36:14,119
fool hardly enough
to jump into a black hole,
533
00:36:14,245 --> 00:36:18,581
at some time on his watch,
say 12 o'clock,
534
00:36:18,995 --> 00:36:21,604
he will cross
the event horizon
535
00:36:21,935 --> 00:36:24,408
and enter the black hole.
536
00:36:25,864 --> 00:36:28,419
But no matter how long you waited,
537
00:36:28,544 --> 00:36:32,856
you would never see the astronaut's
watch reach 12 o'clock.
538
00:36:35,007 --> 00:36:37,954
Instead, each second
on the watch
539
00:36:38,079 --> 00:36:40,171
would appear to take
longer and longer
540
00:36:40,296 --> 00:36:45,086
until the last second before midnight
would take forever.
541
00:36:46,797 --> 00:36:49,929
Thus, by jumping
into a black hole,
542
00:36:50,055 --> 00:36:53,667
one could ensure
that one's image lasted forever.
543
00:36:55,320 --> 00:36:58,213
But the picture
would fade very rapidly
544
00:36:58,338 --> 00:37:02,375
and grow so dim
that no one could see it.
545
00:37:06,284 --> 00:37:08,507
When somebody disappears
into the black hole
546
00:37:08,632 --> 00:37:13,442
as seen from the outside, you...
it looks like time actually slows down.
547
00:37:13,611 --> 00:37:18,486
and the person becomes...
who's moving or at least he thinks
he's moving
548
00:37:18,657 --> 00:37:21,421
and talking in his spaceship
at a normal rate,
549
00:37:21,546 --> 00:37:24,442
seems to slow down
and ends up by being frozen
550
00:37:24,567 --> 00:37:26,415
in a particular position
551
00:37:26,540 --> 00:37:30,376
as seen from somebody watching
from the outside,
552
00:37:30,501 --> 00:37:33,540
and as seen from the outside
you never see what happens after that.
553
00:37:40,184 --> 00:37:43,508
The astronout
wouldn't notice anything special
554
00:37:43,779 --> 00:37:46,398
when his watch
reached midnight
555
00:37:46,717 --> 00:37:49,277
and he crossed
the event horizon
556
00:37:49,402 --> 00:37:51,516
into the black hole.
557
00:37:53,165 --> 00:37:57,333
Until of course he approached
the singularity
558
00:37:57,458 --> 00:37:59,924
and was crushed into spaghetti.
559
00:38:06,501 --> 00:38:09,021
One can fall though
this event horizon
560
00:38:09,146 --> 00:38:11,772
without feeling anything,
without noticing it.
561
00:38:12,332 --> 00:38:15,947
After about a week of falling,
one begins to feel
562
00:38:16,072 --> 00:38:20,504
a pinch, and one extends longer and longer
and gets slightly thinner
563
00:38:21,042 --> 00:38:24,202
and of course one begins
to get squeezed,
564
00:38:24,725 --> 00:38:27,811
until one gets very long
and very thin
565
00:38:27,937 --> 00:38:29,606
and rather nasty.
566
00:38:29,731 --> 00:38:32,832
By the end of two weeks
one's fallen right into the center
567
00:38:32,957 --> 00:38:34,558
and one is of course dead.
568
00:38:35,496 --> 00:38:37,954
Before you lose sight
of the outer world,
569
00:38:38,079 --> 00:38:40,228
you would see things happening
570
00:38:40,353 --> 00:38:42,178
and you would see them
at a greater rate
571
00:38:42,303 --> 00:38:44,192
so that it would look like
a firework display.
572
00:38:44,713 --> 00:38:47,658
And the frustration would be that,
although you would be able
573
00:38:47,783 --> 00:38:49,584
to see everything that happens
in the future,
574
00:38:49,709 --> 00:38:52,078
it would be going so fast
from the scientific point of view,
575
00:38:52,203 --> 00:38:53,917
you would have no time to analyze it,
576
00:38:54,042 --> 00:38:56,450
you wouldn't be able to take it in.
577
00:38:56,628 --> 00:38:59,067
And eventually things
would be going so fast
578
00:38:59,192 --> 00:39:01,845
and it would be so explosive that
you yourself
579
00:39:01,970 --> 00:39:05,419
would be destroyed by the explosion
and that would be the end.
580
00:39:05,544 --> 00:39:09,164
But it would be a very exciting way
to end one's life.
581
00:39:09,624 --> 00:39:13,173
It would be the way I would choose
if I had the choice.
582
00:39:15,869 --> 00:39:18,821
In the long hisroty
of the Universe,
583
00:39:19,122 --> 00:39:22,808
many stars must have
burned up their nucelar fuel
584
00:39:22,987 --> 00:39:25,342
and collapsed in on themselves.
585
00:39:27,578 --> 00:39:30,371
The number of black holes
may be greater
586
00:39:30,496 --> 00:39:32,743
than the number of visibile stars,
587
00:39:32,868 --> 00:39:35,761
which totals about
a hundred thousand million
588
00:39:35,886 --> 00:39:38,352
in our galaxy alone.
589
00:39:40,070 --> 00:39:42,181
We also have evidence
590
00:39:42,306 --> 00:39:45,628
that there is a very large black hole
591
00:39:45,801 --> 00:39:48,838
at the centre of our own galaxy.
592
00:39:55,366 --> 00:39:56,839
Friends ask me:
593
00:39:56,964 --> 00:40:00,167
"Well, if a black hole is black,
how can you see it?"
594
00:40:00,292 --> 00:40:04,179
And i say: "Have you have you ever
been to a ball?"
595
00:40:04,304 --> 00:40:10,333
"Have you ever watched the young man
dressed in their evening tuxedos"
596
00:40:10,459 --> 00:40:15,777
"and the girls in their white dresses,
whirling around, held in each other's arms?"
597
00:40:15,956 --> 00:40:20,224
"And the lights turn low,
and all you can see is the girls."
598
00:40:20,797 --> 00:40:23,813
Well, the girl is the ordinary star
599
00:40:23,938 --> 00:40:26,923
and the boy is the black hole.
600
00:40:27,092 --> 00:40:30,963
You can't see the black hole
any more that you can see the boy,
601
00:40:31,088 --> 00:40:33,080
but the girl going around
602
00:40:33,205 --> 00:40:36,937
gives you convincing evidence
there must be something there,
603
00:40:37,062 --> 00:40:38,890
holding her in orbit.
604
00:40:41,116 --> 00:40:45,976
One evening, shortly after
the birth of my daughter, Lucy,
605
00:40:46,101 --> 00:40:51,111
I started thinking about black holes
as I was getting into bed.
606
00:40:53,627 --> 00:40:57,496
My disability made this
a rather slow process,
607
00:40:57,621 --> 00:41:00,216
so I had plenty of time.
608
00:41:01,583 --> 00:41:03,998
Suddenly, I realized
609
00:41:04,169 --> 00:41:06,579
that the area
of the event horizon
610
00:41:06,704 --> 00:41:09,454
must always increase
with time.
611
00:41:11,760 --> 00:41:15,215
The increase in the area
of the event horizon
612
00:41:15,486 --> 00:41:18,503
was reminiscent of a quantity
called entropy,
613
00:41:18,628 --> 00:41:22,162
which measures the degree of
disorder of a system.
614
00:41:23,478 --> 00:41:26,211
It is a matter of common experience
615
00:41:26,336 --> 00:41:29,685
that disorder tends to
increase with time
616
00:41:29,810 --> 00:41:32,233
if things are left at themselves.
617
00:41:36,215 --> 00:41:39,959
Jacob Bekenstein came in
at the office one day.
618
00:41:40,844 --> 00:41:44,653
"Jakob," I said,
"it always troubles me:"
619
00:41:44,778 --> 00:41:48,328
"when I put a hot tea cup next
to a cold tea cup, I've increased,"
620
00:41:48,453 --> 00:41:51,944
"by letting heat flow
from one to the other,"
621
00:41:52,069 --> 00:41:54,482
"the amount of disorder
in the Universe."
622
00:41:54,607 --> 00:41:57,789
"But Jakob, if a black hole
swirls by,"
623
00:41:57,915 --> 00:42:01,121
"and I drop both tea cups
into this,"
624
00:42:01,512 --> 00:42:05,061
"I can seal the evidence
of my crime, have I not?"
625
00:42:07,635 --> 00:42:10,501
Bekenstein's a man
of great integrity
626
00:42:10,626 --> 00:42:13,783
and he looked troubled,
and he came back to me later
627
00:42:13,908 --> 00:42:18,591
and he said: "No, you have not
concealed the evidence of your crime."
628
00:42:19,062 --> 00:42:22,655
"The black hole records
what's happened to you."
629
00:42:23,637 --> 00:42:26,407
Stephen Hawking read the paper
630
00:42:26,691 --> 00:42:29,939
in which Bekenstein
announced his result
631
00:42:30,258 --> 00:42:32,155
and thought it was preposterous
632
00:42:32,280 --> 00:42:35,298
and he decided to prove
that he was wrong.
633
00:42:39,019 --> 00:42:42,124
My dicoveries led
Jacob Bekenstein
634
00:42:42,250 --> 00:42:45,265
to suggest that
the area of the event horizon
635
00:42:45,435 --> 00:42:49,302
actually was
the entropy of the black hole.
636
00:42:50,678 --> 00:42:55,525
But there was one fatal flaw
in Bekenstein's idea:
637
00:42:56,766 --> 00:42:59,233
if black holes have
an entropy,
638
00:42:59,358 --> 00:43:01,902
they ought to have
a temperature.
639
00:43:04,262 --> 00:43:08,948
And if they have a temperature,
they ought to give off radiation.
640
00:43:11,074 --> 00:43:13,652
But how could they give off radiation
641
00:43:13,777 --> 00:43:16,948
if nothing can escape
from a black hole?
642
00:43:20,949 --> 00:43:25,310
As it turned out, Bekenstein
was basically correct,
643
00:43:25,436 --> 00:43:28,460
thought in a manner far
more surprising
644
00:43:28,585 --> 00:43:32,452
than he, or anyone else,
had expected.
645
00:43:36,994 --> 00:43:39,638
As he gradually lost
the use of his hands,
646
00:43:39,763 --> 00:43:43,666
he had to start developing...
647
00:43:43,791 --> 00:43:47,242
carefully chosing
research projects
648
00:43:47,412 --> 00:43:50,737
that could be tackled and solved
649
00:43:50,862 --> 00:43:55,086
through geometrical arguments
that he could do pictorially in his head.
650
00:43:55,211 --> 00:43:57,527
and he developed a very powerful
set of tools
651
00:43:57,652 --> 00:43:59,542
that noboby else really had
652
00:44:00,203 --> 00:44:03,304
so in some sense,
when you lose one set of tools
653
00:44:03,429 --> 00:44:05,054
you may develop other tools,
654
00:44:05,180 --> 00:44:09,129
but to get new tools on a minimal to
different kind of problems in your tools
655
00:44:09,254 --> 00:44:12,263
and if you're the only master
in the world of this new tools,
656
00:44:12,388 --> 00:44:14,023
that means certain kinds of problems
657
00:44:14,148 --> 00:44:16,078
you can solve and nobody else can.
658
00:44:17,819 --> 00:44:23,292
My work up to 1973
was in General Relativity
659
00:44:23,417 --> 00:44:27,054
and was summurized in a book
which I wrote with George Ellis
660
00:44:27,179 --> 00:44:30,867
called "The large scale structure
of space-time".
661
00:44:33,113 --> 00:44:37,650
Even then, it was difficult for me
to write things down.
662
00:44:39,302 --> 00:44:42,834
So I tended to think in pictures
and diagrams
Aussi, étais-je enclin à penser
en images et en diagrammes
663
00:44:42,959 --> 00:44:45,295
that I could
visualize in my head.
664
00:45:20,282 --> 00:45:22,758
I remember visiting Stephen
and Jane
665
00:45:22,884 --> 00:45:24,834
at their home in Cambrigde.
666
00:45:25,643 --> 00:45:28,002
After supper in the evening
667
00:45:28,127 --> 00:45:31,263
when it was time for Stephen
to go to bed
668
00:45:31,430 --> 00:45:33,988
Jane instisted and Stephen acquiesced,
669
00:45:34,113 --> 00:45:37,341
I guess this was standard,
that Stephen make his way up.
670
00:45:37,467 --> 00:45:40,808
I forgot whether there's one flight of stairs
or two flight of stairs, alone
671
00:45:40,981 --> 00:45:43,555
and this was appearen
that he can no longer walk.
672
00:45:43,680 --> 00:45:48,822
the way he got up the stairs was
he grabbed hold of the pillars
that support the banister
673
00:45:48,948 --> 00:45:53,862
and pulled him up with the strenght of his own,
pulled himself up the stairs by the
strenght of his own arms,
674
00:45:54,133 --> 00:45:58,747
dragging himself up
from the ground floor up to the second storey
675
00:45:58,872 --> 00:46:01,539
in a long, arduous effort.
676
00:46:03,668 --> 00:46:09,009
Jane explained that this
was an important part of his physical therapy
677
00:46:09,134 --> 00:46:13,345
to maintain his coordination
678
00:46:13,470 --> 00:46:16,050
and strenght as long as possible.
679
00:46:16,881 --> 00:46:19,245
at first, it was sort of hard
renting[?] to watch
680
00:46:19,370 --> 00:46:22,355
what appeared to be the agony
of pulling up the starirs
681
00:46:22,480 --> 00:46:26,060
until I understood it was just part of life
682
00:46:26,331 --> 00:46:29,236
pulling himself up the stairs like that.
683
00:46:33,119 --> 00:46:37,734
General Relativity is
what is called a classical theory.
684
00:46:39,573 --> 00:46:40,657
It predicts
685
00:46:40,929 --> 00:46:44,288
a single definite path
for each particle.
686
00:46:45,972 --> 00:46:48,563
But according to
quantum mechanics,
687
00:46:48,688 --> 00:46:52,255
there is an element of chance
or uncertainty.
688
00:46:54,804 --> 00:47:00,731
A particle does not have
just a single path through space and time.
689
00:47:02,372 --> 00:47:06,061
Instead, there is
an uncertainty principle
690
00:47:06,231 --> 00:47:11,390
according to which both the exact position
and velocity of the particle
691
00:47:11,515 --> 00:47:13,689
can never be known.
692
00:47:20,478 --> 00:47:22,371
I began investigating
693
00:47:22,496 --> 00:47:25,500
the effect of quantum mechanics might have
694
00:47:25,625 --> 00:47:28,425
on particles near a black hole.
695
00:47:28,978 --> 00:47:30,164
I found
696
00:47:30,435 --> 00:47:33,791
that particles could escapoe
from a black hole,
697
00:47:34,195 --> 00:47:37,850
that black holes
are not completely black.
698
00:47:39,092 --> 00:47:41,823
At first, I didn't believe it.
699
00:47:42,815 --> 00:47:48,822
But when I ridid the calculations,
I couldn't get the effect to go away.
700
00:47:50,205 --> 00:47:54,026
I met martin Reese
and he was shaking with excitement.
701
00:47:54,151 --> 00:47:56,479
And he said: "Have you heard,
have you heard!"
702
00:47:56,605 --> 00:48:00,193
"What Stephen has discovered? Everything
is different! everything is changed!"
703
00:48:01,246 --> 00:48:03,872
I was still unsure
of my discovery
704
00:48:03,997 --> 00:48:07,200
so I only told
a few colleagues.
705
00:48:07,905 --> 00:48:10,727
But word soon spread.
706
00:48:10,948 --> 00:48:14,457
Roger Penrose phoned up
on my birthday.
707
00:48:15,837 --> 00:48:19,333
He was very excited
and went on so long
708
00:48:19,458 --> 00:48:22,715
that my birthday dinner
got quite cold.
709
00:48:24,433 --> 00:48:26,337
It was a great pity
710
00:48:26,462 --> 00:48:30,153
because it was goose,
which I'm very fond of.
711
00:48:31,411 --> 00:48:35,019
To me it's a miracle, because
it's a complicated and messy calculation.
712
00:48:35,290 --> 00:48:38,017
we can now do these things
very much better
713
00:48:38,332 --> 00:48:40,532
and it's more transparent
what happens.
714
00:48:40,657 --> 00:48:43,736
But out of this messy calculation,
he showed that black holes
715
00:48:44,007 --> 00:48:46,204
aren't black.
With this quanto-mechanical effect
716
00:48:46,329 --> 00:48:48,452
which was a residual radiation.
717
00:48:48,623 --> 00:48:50,576
Stephen came to a meeting
718
00:48:50,847 --> 00:48:52,312
and people were flabbergasted.
719
00:48:52,437 --> 00:48:55,038
I remember someone getting up and saying:
"You must be wrong Stephen."
720
00:48:55,163 --> 00:48:56,874
"I don't believe a word of it!"
721
00:48:57,145 --> 00:48:59,946
I once said that I was unhappy
722
00:49:00,071 --> 00:49:04,089
with the explanation given in terms of
negative energy particles being created.
723
00:49:04,430 --> 00:49:07,152
But I feel this is part
of the controversy of science.
724
00:49:07,277 --> 00:49:08,927
You must have the give and take.
725
00:49:09,052 --> 00:49:11,145
And I'm delighted to be able
to be part of that.
726
00:49:11,270 --> 00:49:13,156
I mean, it's what makes it fun.
727
00:49:13,441 --> 00:49:16,315
You know, if you all sat down
and said: "Oh, lovely!"
728
00:49:16,440 --> 00:49:18,819
when you do have niggling
questions in your mind
729
00:49:18,944 --> 00:49:21,409
that's not doing a good service
to science.
730
00:49:21,534 --> 00:49:24,389
But I was not antagonistic to it
in any way,
731
00:49:24,514 --> 00:49:27,570
except for that one time
when I questioned.
732
00:49:29,358 --> 00:49:31,140
I finally conviced myself
733
00:49:31,265 --> 00:49:33,542
that black holes radiated
734
00:49:33,667 --> 00:49:37,296
when I found a mechanism
through whcih this could happen.
735
00:49:39,464 --> 00:49:41,753
According to quantum mechanics,
736
00:49:41,925 --> 00:49:44,877
space is filled
with virtual particles
737
00:49:45,002 --> 00:49:46,687
and anti-particles
738
00:49:46,812 --> 00:49:49,846
that are constantly
materializing in pairs,
739
00:49:50,141 --> 00:49:53,226
separating,
coming together again
740
00:49:53,395 --> 00:49:55,720
and annihilating
each other.
741
00:49:58,766 --> 00:50:01,338
In the presence of a black hole,
742
00:50:01,463 --> 00:50:04,379
one member of a pair
of virtual particles
743
00:50:04,504 --> 00:50:06,366
may fall into the hole,
744
00:50:06,491 --> 00:50:11,209
leaving the other member without
a partner whith which to annihilate.
745
00:50:12,975 --> 00:50:16,835
The forsaken particle appears
to be radiation
746
00:50:16,960 --> 00:50:19,099
emitted bu the black hole.
747
00:50:23,308 --> 00:50:27,337
And so, black holes
are not eternal.
748
00:50:29,751 --> 00:50:33,259
They evaporate away
at an increasing rate
749
00:50:33,384 --> 00:50:37,453
until they vanish
in a gigantic explosion.
750
00:50:40,448 --> 00:50:44,813
Quantum mechanics has allowed
particles and radiation
751
00:50:44,938 --> 00:50:47,475
to escape from
the ultimate prison:
752
00:50:47,972 --> 00:50:49,587
a black hole.
753
00:50:52,568 --> 00:50:55,856
Einstein never accepted
quantum mechanics
754
00:50:55,981 --> 00:50:59,326
because of its element
of chance and uncertainty.
755
00:51:00,868 --> 00:51:04,543
He said:
"God does not play dice".
756
00:51:05,926 --> 00:51:09,792
It seems that Einstein
was doubly wrong.
757
00:51:12,369 --> 00:51:15,066
The quantum effects
of black holes
758
00:51:15,191 --> 00:51:18,772
suggests that not only
does God play dice,
759
00:51:18,897 --> 00:51:23,144
he sometimes throw them
where they cannot be seen.
760
00:51:25,039 --> 00:51:26,518
He says himself that
761
00:51:27,051 --> 00:51:32,917
he wouldn't have got where he is
if he hadn't been ill.
762
00:51:33,042 --> 00:51:37,454
And I think that's quite possible,
because it's like Johnson said, you know:
763
00:51:37,621 --> 00:51:41,833
"Knowledge to be hanged in the morning
concentrates the mind wonderfully".
764
00:51:42,001 --> 00:51:44,788
And he has concentrated on this
in a way
765
00:51:44,913 --> 00:51:46,791
that I don't think
he would have done
766
00:51:46,916 --> 00:51:49,277
because he always took a great
interest in a lot of things in life
767
00:51:49,402 --> 00:51:52,544
and I don't know if he would have
applied himself in quite the same way
768
00:51:52,669 --> 00:51:55,069
if he'd been able to get around as is.
769
00:51:55,194 --> 00:51:56,763
So in a way...
770
00:51:57,215 --> 00:52:00,976
No, I can't think anyone's lucky
of having an illness like that, even still,
771
00:52:01,144 --> 00:52:05,552
but it's bad less luck for him
that it would be for some people,
if you see what I mean,
772
00:52:05,677 --> 00:52:08,770
because he can so much
live in his head.
773
00:52:09,374 --> 00:52:12,448
When I lived with the Hawking family
I would usually get up around
774
00:52:12,824 --> 00:52:14,612
7h15 or 7h30, and
775
00:52:14,737 --> 00:52:18,365
take a shower and then
read my bible some in the morning and pray.
776
00:52:18,491 --> 00:52:20,730
And then I would go down at 8h15
to get Stephen up.
777
00:52:20,855 --> 00:52:25,203
And then at breakfast I would often
tell him what I'd been reading in the bible
778
00:52:25,328 --> 00:52:29,039
hoping that, you know, maybe this
would eventually have some influence.
779
00:52:29,763 --> 00:52:32,751
So then we would get into work
and usually we'd go and see
780
00:52:33,106 --> 00:52:37,364
if there were any scientific papers
that people sent out and.
781
00:52:38,002 --> 00:52:40,983
I did discover that despite
Hawking's great brains
782
00:52:41,108 --> 00:52:44,862
he reads quite slowly.
I mean, I can read about twice as fast as him.
783
00:52:45,199 --> 00:52:48,410
But of course, the point is
he would have to read to memory
784
00:52:48,536 --> 00:52:52,312
because it would be very difficult
for him to go back and access the thing.
785
00:52:52,583 --> 00:52:55,534
Wherheas I can skim the paper
rather quickly
786
00:52:55,659 --> 00:52:58,353
and see if there was anything interesting in it and
if I wanted to work on it
787
00:52:58,479 --> 00:53:00,910
I can pick the thing up and look at it.
788
00:53:03,036 --> 00:53:04,971
Black hole radiation
789
00:53:05,096 --> 00:53:08,001
has shown us that
gravitational collapse
790
00:53:08,127 --> 00:53:11,051
is not as final
as we once thought.
791
00:53:12,904 --> 00:53:16,205
If an astronaut falls
into a black hole,
792
00:53:16,330 --> 00:53:19,673
he will be returned
to the rest of the Universe
793
00:53:19,846 --> 00:53:22,171
in the form of radiation.
794
00:53:23,716 --> 00:53:25,596
Thus, in a sense,
795
00:53:25,721 --> 00:53:28,595
the astronaut will be recycled.
796
00:53:30,557 --> 00:53:34,564
However, it would be
a poor sort of immortality
797
00:53:34,689 --> 00:53:39,003
because any personal concept of time
would come to an end
798
00:53:39,128 --> 00:53:43,487
as he is torn apart
inside a black hole.
799
00:53:46,535 --> 00:53:51,397
All that would survive
would be his mass, or energy.
800
00:53:57,100 --> 00:53:59,883
One year the Hawkings
took me along
801
00:54:00,008 --> 00:54:04,049
when we went to a cottage
in Wales near the river Wye.
802
00:54:04,306 --> 00:54:06,813
And this cottage was
up a hill
803
00:54:06,938 --> 00:54:09,508
and there was a bit of a
804
00:54:10,029 --> 00:54:13,507
paved, well, sidewalk
that went up to the cottage
805
00:54:13,632 --> 00:54:15,737
which I had not been up.
806
00:54:15,862 --> 00:54:19,750
And of course I wanted to do it
in the least number of trips that I could imagine,
807
00:54:19,875 --> 00:54:22,482
so we put Stephen's batteries
under his chair, I mean
808
00:54:22,608 --> 00:54:25,619
his wheelchair has space for batteries,
and put extra batteries under there, which we...
809
00:54:25,744 --> 00:54:28,221
Stephen didn't realize he had...
that I put under there,
810
00:54:28,347 --> 00:54:30,658
he didn't realize his chair
was as heavily laden as possible.
811
00:54:31,263 --> 00:54:34,576
So Stephen was quite a bit ahead of me
and then he was turning the corner
to go on to...
812
00:54:34,701 --> 00:54:37,673
around to his house,
but that was on a slope and...
813
00:54:37,798 --> 00:54:39,870
So I looked up and I noticed
814
00:54:39,995 --> 00:54:42,071
Stephen's wheelchair
was slowly tipping backward.
815
00:54:42,197 --> 00:54:45,503
And of course that was about
10 meters away.
816
00:54:46,405 --> 00:54:48,197
I tried to roll up there
817
00:54:48,322 --> 00:54:50,453
but of course I wasn't able to get there
nearly rapidly enough
818
00:54:50,578 --> 00:54:53,333
before he've toppled over backward
into the bushes.
819
00:54:53,459 --> 00:54:56,476
And this was a bit
of a shocking sight,
820
00:54:56,601 --> 00:55:01,605
to see this master of gravity getting
overcome by the weak gravitational force of Earth!
821
00:55:03,001 --> 00:55:06,781
One of the worst things for me
would be having people there all the time,
822
00:55:06,906 --> 00:55:10,063
never alone I reckon, really.
823
00:55:10,620 --> 00:55:13,051
And yet he finds thigs funny
824
00:55:13,176 --> 00:55:16,532
and he enjoys life and he goes
dashing about all over the place.
825
00:55:16,831 --> 00:55:18,605
And I think this is tremendous,
826
00:55:18,730 --> 00:55:20,854
that this is the sort of courage I haven't got,
827
00:55:20,979 --> 00:55:22,925
that his father hadn't got.
828
00:55:23,050 --> 00:55:24,995
And we cannot but admire it,
829
00:55:25,120 --> 00:55:28,214
but I wonder
how on earth he got it, really!
830
00:55:28,736 --> 00:55:31,670
There must have been 50 people there
831
00:55:31,795 --> 00:55:34,561
and I was standing off
in a corner, sort of,
832
00:55:34,686 --> 00:55:38,789
watching quietly
for a few minutes, relaxing.
833
00:55:38,914 --> 00:55:43,645
And Stephen was not far from me.
Jane walked over to Stephen
834
00:55:43,770 --> 00:55:46,693
and looked at him and he was
sitting with his head on his lap,
835
00:55:46,818 --> 00:55:49,302
like only Stephen can put
his head in his lap,
836
00:55:49,427 --> 00:55:53,938
and Jane said to Stephen:
"You look miserable Stephen!"
837
00:55:54,064 --> 00:55:55,268
Sit up straight!"
838
00:55:55,393 --> 00:55:57,375
"Some of your guests
don't understand"
839
00:55:57,500 --> 00:56:00,439
"that you're sitting there thinking
about physics and having a wonderful time,"
840
00:56:00,564 --> 00:56:03,749
"it looks like you're in pain.
Sit up straight and go talk to your guests."
841
00:56:05,959 --> 00:56:12,013
In 1979, I was elected
Lucasian Professor of Mathematics.
842
00:56:14,046 --> 00:56:18,180
This is the same chair
once held by Isaac Newton.
843
00:56:20,559 --> 00:56:22,227
They a have a big book
844
00:56:22,352 --> 00:56:26,771
which every university
teaching officer is supposed to sign.
845
00:56:28,469 --> 00:56:32,284
After I had been Lucasian Professor
for about a year
846
00:56:32,409 --> 00:56:35,708
they realized I had never signed.
847
00:56:36,984 --> 00:56:39,782
So they brought the book
to my office
848
00:56:39,907 --> 00:56:42,734
and I signed it
with some difficulty.
849
00:56:44,365 --> 00:56:48,234
That was the last time
I signed my name.
850
00:56:59,493 --> 00:57:03,269
My interest in the origin
and fate of the Universe
851
00:57:03,394 --> 00:57:06,394
was reawakened
when I attended a conference
852
00:57:06,519 --> 00:57:09,150
on cosmology in the Vatican.
853
00:57:11,124 --> 00:57:15,401
Afterwards, we were granted
an audience with the pope.
854
00:57:16,536 --> 00:57:21,826
He told us that it was all right to study
the evolution of the Universe
855
00:57:21,999 --> 00:57:23,583
after the Big Bang,
856
00:57:24,807 --> 00:57:28,179
but we should not inquire
into the Big Bang itself,
857
00:57:28,494 --> 00:57:31,406
because that was
the moment of creation,
858
00:57:31,531 --> 00:57:34,263
and therefore, the work of God.
859
00:57:36,526 --> 00:57:39,537
I was glad that he did not know
860
00:57:39,663 --> 00:57:43,013
the subject of the talk
I had just given:
861
00:57:44,772 --> 00:57:48,711
the possibility that
the Universe had no beginning,
862
00:57:48,836 --> 00:57:51,347
no moment of creation.
863
00:57:56,964 --> 00:57:59,193
There were theories in the early 70s,
in fact the first type
864
00:57:59,318 --> 00:58:00,621
of creation theories,
865
00:58:00,746 --> 00:58:02,767
where the people concerned
started off with
866
00:58:02,893 --> 00:58:06,703
a fixed external space and time which
for eternity was empty.
867
00:58:06,828 --> 00:58:09,956
Then suddenly, for some unknown reason,
Universe nucleates
868
00:58:10,227 --> 00:58:12,925
in a point and then Bang!
It blows apart.
869
00:58:13,050 --> 00:58:16,796
But the trouble is that when
the space and time appear
in the classical theory
870
00:58:17,067 --> 00:58:20,280
the actual point itself
is a singualr point in the mathematics.
871
00:58:20,405 --> 00:58:22,464
Mathematics breaks down,
872
00:58:22,589 --> 00:58:25,304
and so you cannot in fact use that
to give you a creation theory.
873
00:58:27,110 --> 00:58:29,204
If one goes back in time,
874
00:58:29,329 --> 00:58:32,770
one comes to
the Big Bang singularity,
875
00:58:32,944 --> 00:58:36,051
where then laws of Physics
break down.
876
00:58:37,560 --> 00:58:40,345
But there's another
direction of time
877
00:58:40,470 --> 00:58:42,284
that one can go in,
878
00:58:42,453 --> 00:58:44,910
which avoids the singularity.
879
00:58:46,667 --> 00:58:50,944
This is called
the imaginary direction of time.
880
00:58:52,517 --> 00:58:54,522
In imaginary time,
881
00:58:54,647 --> 00:58:57,624
there need not be any sigularities
882
00:58:57,801 --> 00:59:01,633
which form a beginning
or end to time.
883
00:59:05,225 --> 00:59:08,276
When you come to imaginary time,
you have this rather peculiar possibility
884
00:59:08,401 --> 00:59:10,434
of having a 'now', as it were,
885
00:59:10,559 --> 00:59:15,741
not necessarily having a sort
of a chain of past moments.
886
00:59:15,866 --> 00:59:19,870
If we start to lay out the moments
that run in backwards in time, as it were,
887
00:59:19,995 --> 00:59:22,777
then for a long time
things work perfectly normally.
888
00:59:23,274 --> 00:59:25,803
But then as you begin to get
further and furhter back towards
889
00:59:25,928 --> 00:59:29,042
what would be the origin point
in a conventional real time picture
890
00:59:29,167 --> 00:59:32,124
you'd find that
the nature of time changes,
891
00:59:32,250 --> 00:59:35,873
that the imaginary component
becomes more and more prominent,
892
00:59:36,144 --> 00:59:39,373
and in the end, what ought be a singular point
in the classical theory
893
00:59:39,498 --> 00:59:40,677
just gets smoothed away
s'estompe
894
00:59:40,802 --> 00:59:43,421
and you have this beautiful picture,
this bowls,
895
00:59:43,546 --> 00:59:45,533
where the creation of the Universe
896
00:59:45,659 --> 00:59:47,760
is pictured, as where we are now
897
00:59:48,031 --> 00:59:51,553
in a smooth sort of bowl past
where there's no initial point,
just a sort of smooth shape.
898
00:59:59,308 --> 01:00:02,573
So long as the Universe
had a beginning,
899
01:00:02,698 --> 01:00:05,567
we could suppose
it had a Creator.
900
01:00:07,410 --> 01:00:11,172
But if the Universe
is completely self-contained,
901
01:00:11,484 --> 01:00:13,996
having no boudary or edge,
902
01:00:15,324 --> 01:00:18,749
it would neither be created
nor destroyed,
903
01:00:19,868 --> 01:00:22,024
it would simply be.
904
01:00:24,562 --> 01:00:27,984
What place then, for a Creator?
905
01:00:32,282 --> 01:00:34,359
What we can really say
is that the Universe is,
906
01:00:34,484 --> 01:00:36,557
bacuse it is a self-consistent
mathematical structure.
907
01:00:36,682 --> 01:00:39,869
There's no past because,
unlike the creation point scenario
908
01:00:39,994 --> 01:00:41,803
there's nothing for it to
909
01:00:41,928 --> 01:00:45,066
So to say it's created from nothing
is actually a bit of a misnomer,
910
01:00:45,191 --> 01:00:48,075
it's a misleading use
of the word 'nothing'.
911
01:00:48,243 --> 01:00:51,127
It's not just that there was empty space
in which the Universe appeared,
912
01:00:51,252 --> 01:00:53,344
which you might call 'nothing',
there was really nothing at all
913
01:00:53,470 --> 01:00:55,375
because there wasn't even
a creation event, you see.
914
01:00:55,500 --> 01:00:59,650
The use of past tense in a verb
becomes inappropriate in these theories.
915
01:00:59,775 --> 01:01:01,653
Unfortunately, tenses were set up
916
01:01:01,778 --> 01:01:03,578
when people believed
in real time, of course,
917
01:01:03,704 --> 01:01:07,129
and we don't yet have a linguistic form
to describe tenses in imaginary time.
918
01:01:07,927 --> 01:01:11,874
The word 'time' was not
handed down from Heaven,
919
01:01:11,999 --> 01:01:14,022
as a gift from On High.
920
01:01:14,147 --> 01:01:19,201
The idea of 'time' is
a word inventend my men,
921
01:01:19,592 --> 01:01:23,499
and if it has puzzlements connected with it,
whose fault is it?
922
01:01:23,624 --> 01:01:24,980
It's our fault!
923
01:01:28,215 --> 01:01:32,573
Where does the difference
between the past and the future come from?
924
01:01:35,289 --> 01:01:37,175
The laws of science
925
01:01:37,300 --> 01:01:40,733
do not distinguish
between the past and the future.
926
01:01:42,188 --> 01:01:46,868
Yet, there is a big difference
between the past and future
927
01:01:46,993 --> 01:01:48,729
in ordinary life.
928
01:01:55,082 --> 01:01:58,524
You may see a cup of tea
fall off a table
929
01:01:58,649 --> 01:02:01,585
and break into peaces
on the floor,
930
01:02:01,936 --> 01:02:05,841
but you will never see
a cup gather together
931
01:02:05,966 --> 01:02:08,326
and jump back on the table.
932
01:02:11,164 --> 01:02:14,252
The increase of disorder
or entropy
933
01:02:14,377 --> 01:02:17,861
is what distiguishes
the past from the future,
934
01:02:18,039 --> 01:02:20,660
giving the direction to time.
935
01:02:26,962 --> 01:02:28,933
He fell ill in Switzerland.
936
01:02:29,287 --> 01:02:32,546
When he came back,
he was on a ventilator.
937
01:02:32,817 --> 01:02:35,837
Because he was on a ventilator,
you've got a tube down you throat,
938
01:02:35,962 --> 01:02:38,218
and therefore you can't speak,
just for that reason.
939
01:02:38,906 --> 01:02:41,499
For that period, which
might have been a couple of months,
940
01:02:41,624 --> 01:02:46,356
I spent probably one in two nights,
one in three nights, at the hospital,
941
01:02:46,525 --> 01:02:49,392
because when he was in hospital
942
01:02:49,796 --> 01:02:52,364
he couldn't communicate
with the nurses.
943
01:02:52,489 --> 01:02:54,778
And it's not just like
being seriously ill,
944
01:02:54,903 --> 01:02:56,783
but you're in a position where
the nurses
945
01:02:56,908 --> 01:02:58,874
couldn't understand what
Stephen wanted.
946
01:02:58,999 --> 01:03:01,532
If Stephen was unconfortable,
they couldn't tell why.
947
01:03:04,435 --> 01:03:06,511
Before I caught pneumonia,
948
01:03:06,636 --> 01:03:09,492
my speech had been getting
more slurred
949
01:03:09,617 --> 01:03:13,162
so that only a few people
who knew me well
950
01:03:13,287 --> 01:03:15,558
could understand me.
951
01:03:16,694 --> 01:03:19,453
But at least
I could communicate.
952
01:03:21,548 --> 01:03:26,021
I wrote scientific papers
by dictating to a secretary
953
01:03:26,189 --> 01:03:29,612
and I gave seminars
through an interpreter.
954
01:03:30,198 --> 01:03:33,267
And then, a tracheotomy
operation
955
01:03:33,392 --> 01:03:36,605
removed my ability
to speak altogether.
956
01:03:40,872 --> 01:03:43,862
After a long time,
well it seemed like along time,
957
01:03:43,987 --> 01:03:46,652
somebody came up
with this brilliant gadget.
958
01:03:46,777 --> 01:03:49,306
They didn't have it
in Cambridge hosptal,
959
01:03:49,431 --> 01:03:51,580
they got it from
somewhere in London.
960
01:03:51,755 --> 01:03:55,669
This was high technology:
how can you communicate
with a person with no voice?
961
01:03:55,842 --> 01:03:59,495
It's plastic piece of Perspex,
about so big,
962
01:03:59,620 --> 01:04:04,268
and you've got the letters of the alphabet
arranged like that and a hole in the middle.
963
01:04:04,394 --> 01:04:07,722
You hold it up between you
and the other person
964
01:04:07,993 --> 01:04:10,676
and they look at a letter,
and you can see of course
which letter they're looking at,
965
01:04:10,801 --> 01:04:13,346
most of the time,
sometimes you can't quite be sure,
966
01:04:13,471 --> 01:04:16,487
and so you get the patient
to spell out what they wanted, you know,
967
01:04:16,654 --> 01:04:19,523
so each letter you have to look:
speak out the A,
968
01:04:19,648 --> 01:04:22,945
and you say: "A?" You get it right.
It's like a guessing game.
969
01:04:45,391 --> 01:04:49,042
Stephen wasn't going to accept
that he wasn't going to speak again
970
01:04:49,469 --> 01:04:53,126
and he thought that he would be
giving in by trying to find
971
01:04:53,251 --> 01:04:55,852
a method of communicating
without speech.
972
01:04:56,676 --> 01:04:59,649
And I remember
I went to him one evening,
973
01:05:00,181 --> 01:05:02,827
and this was the first time
that he asked
974
01:05:02,952 --> 01:05:05,744
to be gotten out of bed
to use a computer.
975
01:05:05,869 --> 01:05:09,352
Sometimes, they were sitting him up
so that he wasn't lying in the bed all the time,
976
01:05:09,477 --> 01:05:10,930
as you do with a patient,
977
01:05:11,056 --> 01:05:15,497
but this time, when I turned up,
he asked the nurse
could he be gotten out of bed
978
01:05:15,771 --> 01:05:19,249
so he could use the computer,
and he did.
979
01:05:19,374 --> 01:05:22,636
I remember the first thing he typed
in there, after saying 'hello',
980
01:05:22,761 --> 01:05:25,275
-Stephen's always being
very polite about things like that-
981
01:05:25,807 --> 01:05:29,593
was: "Will you help me
finish my book?"
982
01:05:35,265 --> 01:05:39,603
A computer expert in California
heard of my plight
983
01:05:39,861 --> 01:05:44,288
and sent me a computer program
called Equalizer.
984
01:05:46,471 --> 01:05:49,199
This allowed me
to select words
985
01:05:49,324 --> 01:05:52,092
from a series of menus
on a screen
986
01:05:52,370 --> 01:05:55,333
by pressing a switch
in my hand.
987
01:05:59,161 --> 01:06:03,479
These words could then
be sent to a speech synthesizer
988
01:06:03,604 --> 01:06:05,892
attached to my wheelchair.
989
01:06:08,285 --> 01:06:10,166
Much to my surprise,
990
01:06:10,292 --> 01:06:13,112
I found I was able to communicate
991
01:06:13,237 --> 01:06:15,224
much better than before.
992
01:06:18,954 --> 01:06:21,813
When eventually
he went home from hospital,
993
01:06:21,938 --> 01:06:24,740
and he was told he needed 24h nursing,
994
01:06:24,865 --> 01:06:27,429
and everyone was saying:
"Well, how is he gonna go in and do work,"
995
01:06:27,554 --> 01:06:30,815
"is he going to trail around
with a series of nurses after him
working in the office?"
996
01:06:30,940 --> 01:06:32,561
And of course he did!
997
01:06:32,686 --> 01:06:36,462
I mean, they talked originally
of him working at home,
998
01:06:36,907 --> 01:06:39,160
which he wasn't happy with,
999
01:06:40,903 --> 01:06:44,328
so after a period
of recuperation home
1000
01:06:44,453 --> 01:06:46,822
he just decided
to go back into the office,
1001
01:06:47,093 --> 01:06:49,013
and he made the trip
Il faisait donc le trajet
1002
01:06:49,138 --> 01:06:53,013
from his house to the office which is,
I don't know, half a mile, in his wheelchair,
1003
01:06:53,139 --> 01:06:55,071
And the nurses
were walking along with him.
1004
01:06:55,196 --> 01:06:57,529
And this is at the time when
he was still driving around
1005
01:06:57,654 --> 01:06:59,843
with a bag and a nasal drip[?].
1006
01:06:59,968 --> 01:07:04,228
Going into the department, working,
going back home.
1007
01:07:07,877 --> 01:07:09,608
I began to wonder
1008
01:07:09,733 --> 01:07:13,317
what would happen
when the Universe stopped expanding
1009
01:07:13,614 --> 01:07:15,886
and began to contract.
1010
01:07:17,430 --> 01:07:22,415
Would we see broken cups
gather themselves together off the floor
1011
01:07:22,540 --> 01:07:25,362
and jump back on to the table?
1012
01:07:27,383 --> 01:07:31,111
Would we be able
to remember tomorrow's prices
1013
01:07:31,236 --> 01:07:34,110
and make a fortune
off the stock market?
1014
01:07:36,596 --> 01:07:41,689
It seemed to me the Universe
had to return to a smooth and ordered state
1015
01:07:41,814 --> 01:07:43,943
when it recollapsed.
1016
01:07:46,623 --> 01:07:50,036
If this were so,
time would go backwards
1017
01:07:50,161 --> 01:07:52,900
when the Universe
began to collapse.
1018
01:07:55,150 --> 01:07:59,232
People in the contracting phase
would live their lives backwards,
1019
01:07:59,357 --> 01:08:01,982
they would die before they were born
1020
01:08:02,107 --> 01:08:05,706
and get younger
as the Universe got small again.
1021
01:08:06,833 --> 01:08:10,614
Eventually, they would
return to the womb.
1022
01:08:14,059 --> 01:08:16,349
He gave me
my first problem to do.
1023
01:08:17,095 --> 01:08:20,842
He asked me to look at
this mathematical problem
1024
01:08:20,967 --> 01:08:22,799
and ususally,
when he gives a problem,
1025
01:08:22,924 --> 01:08:25,256
he has a good idea
of what the answer should be.
1026
01:08:25,381 --> 01:08:27,116
And I went to look at it
1027
01:08:27,486 --> 01:08:30,600
and it took me a few months
to understand what was it about
1028
01:08:30,726 --> 01:08:33,212
and I came back and I said:
"Stephen I get this answer."
1029
01:08:33,337 --> 01:08:37,225
And he said to me: "No,
that is not what I expected."
1030
01:08:37,350 --> 01:08:39,046
I said: "Stephen that's what I get."
1031
01:08:39,171 --> 01:08:41,330
And so I went to the blackboard,
explained to him what it was.
1032
01:08:41,455 --> 01:08:44,001
He said: "Did you think about that
particular case?"
1033
01:08:44,126 --> 01:08:45,323
I said: "Oh no I didn't!"
1034
01:08:46,010 --> 01:08:47,412
So I went back
1035
01:08:47,537 --> 01:08:50,270
I calculated
what he talked to me about,
1036
01:08:50,395 --> 01:08:51,874
came back a few weeks after
and I said:
1037
01:08:52,145 --> 01:08:57,077
"Stephen, I don't get this thing.
I still get the same answer
I had originally."
1038
01:08:57,860 --> 01:09:01,558
So he said to me:
"No no no, this is not right,"
1039
01:09:01,683 --> 01:09:03,678
"did you think about that?"
"Oh no!"
1040
01:09:03,803 --> 01:09:05,471
"I'd forgotten about that particular case."
1041
01:09:05,742 --> 01:09:07,751
So I went back to the drawing board,
1042
01:09:07,876 --> 01:09:11,167
started calculating again.
And again, get the same answer!
1043
01:09:11,292 --> 01:09:15,189
I went back to see Stephen, and this
dragged on for about 2 or 3 months.
1044
01:09:16,798 --> 01:09:19,068
Finally he said to me: "Maybe,"
1045
01:09:19,339 --> 01:09:21,634
"one of you approximations
isn't valid."
1046
01:09:23,319 --> 01:09:25,894
So me and a collegue decided
to do this thing with computers,
1047
01:09:26,869 --> 01:09:29,625
and than this takes a lot of time
to write the programs
1048
01:09:29,750 --> 01:09:31,955
and to be sure
the program was correct...
1049
01:09:32,226 --> 01:09:35,294
We get the answer and it was
still the way that I said before and
1050
01:09:35,419 --> 01:09:37,270
not the way that Stephen has said,
1051
01:09:37,395 --> 01:09:40,005
so we went to see Stephen
and we said: "You see? Again!"
1052
01:09:43,953 --> 01:09:45,986
I had make a mistake.
1053
01:09:48,248 --> 01:09:52,435
I had been using too simple
a model of the Universe.
1054
01:09:54,691 --> 01:09:56,958
Time will not reverse direction
1055
01:09:57,083 --> 01:09:59,649
when the Universe
begins to contract.
1056
01:10:03,190 --> 01:10:05,940
People will continue to get older,
1057
01:10:06,066 --> 01:10:10,213
so it is no good waiting
until the universe recollapses
1058
01:10:10,338 --> 01:10:12,439
to return to our youth.
1059
01:10:28,699 --> 01:10:31,431
Einstein once
asked a question:
1060
01:10:31,556 --> 01:10:36,224
"How much choice did God have
in constructing the Universe?"
1061
01:10:38,743 --> 01:10:43,289
If my proposal that the universe
has no boundary is correct,
1062
01:10:43,627 --> 01:10:45,709
he had no freedom at all
1063
01:10:45,835 --> 01:10:48,691
to choose how
the Universe began.
1064
01:10:50,377 --> 01:10:52,844
He would only had had
a freedom
1065
01:10:52,969 --> 01:10:55,991
to choose the laws
the Universe obeyed.
1066
01:10:57,856 --> 01:11:02,292
This, however, may not have been
all that much of a choice.
1067
01:11:04,469 --> 01:11:07,755
They may be well be
only one unified theory
1068
01:11:07,931 --> 01:11:11,734
that allows for the existence
of structures as complicated
1069
01:11:11,859 --> 01:11:13,491
as human beings,
1070
01:11:13,771 --> 01:11:17,126
who can investigate
the laws of the Universe
1071
01:11:17,446 --> 01:11:20,179
and ask about
the nature of God.
1072
01:11:28,524 --> 01:11:31,478
I don't know how clear-cut
these experiments are,
1073
01:11:31,603 --> 01:11:35,330
but there are experiments that
have been done on, sort of,
timing of conciousness,
1074
01:11:35,702 --> 01:11:38,577
and they seem to lead
to a very odd picture
1075
01:11:38,702 --> 01:11:41,641
which doesn't even quite
make consistent sense.
1076
01:11:41,766 --> 01:11:45,590
Whether refinement of these experiments
might actually get rid
of this kind of anomaly
1077
01:11:45,715 --> 01:11:46,886
I'm not sure,
1078
01:11:47,011 --> 01:11:50,843
but it does look a little as though
there's something very odd about conciousness,
1079
01:11:50,968 --> 01:11:54,687
and somehow almost as though
future affects the past in some way
1080
01:11:54,812 --> 01:11:56,636
over a very tiny limited scale
1081
01:11:56,761 --> 01:12:00,267
but something maybe of the order
of a reasonable fraction of a second.
1082
01:12:01,007 --> 01:12:03,782
And there's no reason to believe
1083
01:12:04,125 --> 01:12:08,707
that one's conscious experience
shouldn't be part of somebody else's
1084
01:12:08,832 --> 01:12:10,287
at some other stage, I mean.
1085
01:12:10,412 --> 01:12:13,816
I don't if it's fair to say what happens
after one dies but you could...
1086
01:12:13,941 --> 01:12:16,305
it's a plausible picture
1087
01:12:16,665 --> 01:12:18,578
that you could be sombody else.
1088
01:12:18,750 --> 01:12:22,330
And that somebody else could be somebody
who lived in the past, not in the future.
1089
01:12:25,696 --> 01:12:29,670
If there's only one
possible unified theory
1090
01:12:29,796 --> 01:12:33,083
that is just a set of
rules and equations,
1091
01:12:34,565 --> 01:12:38,096
what is it that breathes fire
into the equations
1092
01:12:38,221 --> 01:12:41,718
and makes a Universe
for them to describe?
1093
01:12:43,731 --> 01:12:48,026
Why does the Universe go
to all the bother of existing?
1094
01:12:50,111 --> 01:12:52,981
Is the unified theory
so compelling
1095
01:12:53,106 --> 01:12:56,158
that it brings about
its own existence?
1096
01:12:57,311 --> 01:12:59,937
Or does it need a Creator?
1097
01:13:00,947 --> 01:13:04,745
And if so,
who created Him?
1098
01:13:14,110 --> 01:13:17,224
I think I would say
that the Universe has a purpose,
1099
01:13:17,349 --> 01:13:20,633
it's not somehow just there
by chance,
1100
01:13:20,758 --> 01:13:22,380
I mean, I think it's...
1101
01:13:28,635 --> 01:13:32,009
Some people, I think, take the view
that the Universe is just there
1102
01:13:32,135 --> 01:13:35,225
and it sort of rumbles along
and it just sort of computes,
1103
01:13:35,350 --> 01:13:38,738
we happen somehow by accident
and found ourselves in this thing.
1104
01:13:38,912 --> 01:13:42,982
But I don't think
that's a very fruitful
1105
01:13:43,107 --> 01:13:45,413
or helpful way
of looking at the Universe.
1106
01:13:45,706 --> 01:13:48,581
I think that there's
something much deeper about it.
1107
01:13:50,748 --> 01:13:54,480
In real time,
the time in which we live,
1108
01:13:54,764 --> 01:13:58,545
the Universe has two
possible destinies:
1109
01:13:59,538 --> 01:14:02,543
it may continue
to expand forever,
1110
01:14:04,453 --> 01:14:09,448
or it may recollapse
and come to an end at a Big Crunch.
1111
01:14:11,466 --> 01:14:14,235
It would be rather like
the big Bang,
1112
01:14:14,599 --> 01:14:16,247
but in reverse.
1113
01:14:18,519 --> 01:14:24,448
I now believe that the Universe
will come to an end at a Big Crunch.
1114
01:14:25,788 --> 01:14:28,844
I do, however,
have certain advantages
1115
01:14:28,969 --> 01:14:32,182
over many other prophets of doom:
1116
01:14:34,027 --> 01:14:37,488
whatever happens
10 billion years from now,
1117
01:14:37,613 --> 01:14:41,579
I don't expect to be around
to be proved wrong.
1118
01:14:44,394 --> 01:14:48,387
Of all the pictures that I know,
1119
01:14:48,512 --> 01:14:51,546
the simplest of any cosmology
1120
01:14:51,672 --> 01:14:54,492
is that in which the Universe
is closed,
1121
01:14:54,770 --> 01:14:56,972
has a finite lifetime,
1122
01:14:57,177 --> 01:15:00,496
and collapses with the same
kind of collapse
1123
01:15:00,797 --> 01:15:02,486
that a black hole does.
1124
01:15:04,734 --> 01:15:10,328
If it should turn out that indeed
the Universe is limited in its life,
1125
01:15:12,193 --> 01:15:17,304
how is that different
from the life of each one of us?
1126
01:15:27,424 --> 01:15:30,068
On the evening of Tuesday,
March 5th,
1127
01:15:30,194 --> 01:15:32,435
at about 10h45,
1128
01:15:32,648 --> 01:15:36,147
I was returning to my flat
in Pinehurst.
1129
01:15:38,027 --> 01:15:40,574
It was dark and raining.
1130
01:15:41,870 --> 01:15:43,983
I came up to Grange Road
1131
01:15:44,108 --> 01:15:46,620
and saw headlights approaching,
1132
01:15:46,745 --> 01:15:49,375
but judged that
they were far enough away
1133
01:15:49,500 --> 01:15:51,699
that I could cross safely.
1134
01:15:54,205 --> 01:15:57,702
The vehicle must have been
travelling very fast,
1135
01:15:58,074 --> 01:16:01,593
for when I got just past
the middle of the road,
1136
01:16:01,718 --> 01:16:04,888
my nurse screamed:
"Look out!"
1137
01:16:06,958 --> 01:16:09,061
I heard tires skidding
1138
01:16:09,186 --> 01:16:13,291
and my wheelchair was struck
a tremendous blow in the back.
1139
01:16:15,101 --> 01:16:16,891
I ended up in the road,
1140
01:16:17,016 --> 01:16:20,442
with my legs over the remains
of the wheelchair.
1141
01:16:22,333 --> 01:16:25,367
The accident destroyed
my wheelchair
1142
01:16:25,492 --> 01:16:27,923
and damaged my computer system
1143
01:16:28,048 --> 01:16:30,230
with which I communicate.
1144
01:16:32,448 --> 01:16:36,449
I required 13 stitches in my head,
1145
01:16:37,740 --> 01:16:42,272
but I was able to go back to work
several days later.
1146
01:16:47,680 --> 01:16:50,697
The memories I have
are very much,
1147
01:16:51,159 --> 01:16:52,641
kind of,
1148
01:16:52,996 --> 01:16:56,219
visual pictures
of what Stephen was.
1149
01:16:56,397 --> 01:17:00,309
I've seen Stephen
in certains situations.
1150
01:17:01,318 --> 01:17:03,206
He was always moving,
1151
01:17:03,672 --> 01:17:04,933
always.
1152
01:17:05,323 --> 01:17:07,541
He was hardly ever still.
1153
01:17:08,797 --> 01:17:12,778
It was the same thing
about his face and gestures,
1154
01:17:13,084 --> 01:17:15,497
which he used a great deal,
I should say.
1155
01:17:15,623 --> 01:17:18,097
But it's only memory.
1156
01:17:19,513 --> 01:17:22,050
I found some photographs recently
1157
01:17:22,175 --> 01:17:26,002
which reminded me
of the general look of everybody.
1158
01:17:26,760 --> 01:17:30,369
I must say Stephen looked
very much as he does now.
1159
01:17:31,150 --> 01:17:33,945
If one thinks of him like that.
1160
01:17:40,954 --> 01:17:43,919
He does believe very intensely
1161
01:17:45,552 --> 01:17:49,566
in almost infinite possibility
of the human mind.
1162
01:17:50,129 --> 01:17:52,354
You have to find out
what you can't know
1163
01:17:52,479 --> 01:17:54,526
before you know you can't,
don't you?
1164
01:17:54,651 --> 01:17:58,824
So I don't think that
thought should be restricted at all,
1165
01:17:58,999 --> 01:18:02,927
and there's... why shouldn't you
go on thinking about the unthinkable?
1166
01:18:03,052 --> 01:18:05,172
Somebody's got to start sometime.
1167
01:18:05,297 --> 01:18:08,759
I mean, think how many things were
unthinkable a century ago.
1168
01:18:08,884 --> 01:18:10,881
And yet people have thought them.
1169
01:18:11,006 --> 01:18:13,546
And often they seemed
quite impractical.
1170
01:18:14,414 --> 01:18:16,946
Not all things Stephen says
1171
01:18:17,071 --> 01:18:19,730
probably are to be taken
as Gospel.
1172
01:18:19,855 --> 01:18:22,339
truth is, he's a searcher,
he's looking for things
1173
01:18:22,464 --> 01:18:26,182
and if he is sometimes,
he probably talks nonsense as we all...
1174
01:18:26,359 --> 01:18:28,489
but the point is:
1175
01:18:29,748 --> 01:18:31,953
people must think.
1176
01:18:32,079 --> 01:18:34,117
People must go on thinking.
1177
01:18:34,242 --> 01:18:37,797
They must try to extend the boundaries
of knowledge,
1178
01:18:37,922 --> 01:18:40,324
and they don't sometimes even know
where to start.
1179
01:18:42,084 --> 01:18:45,129
We don't know where
the boundaries are, do we?
1180
01:18:45,448 --> 01:18:48,660
We don't know what
the taking off point is.
1181
01:18:57,744 --> 01:19:01,507
If we do discover
a complete theory of the Universe,
1182
01:19:01,632 --> 01:19:04,073
it should, in time,
be understandable,
1183
01:19:04,198 --> 01:19:06,603
in broad principle,
by everyone,
1184
01:19:06,910 --> 01:19:09,410
not just a few scientists.
1185
01:19:14,206 --> 01:19:15,683
Then we shall all,
1186
01:19:15,966 --> 01:19:20,742
phylosophers, scientists and just
ordinary people,
1187
01:19:20,913 --> 01:19:25,061
be able to take part
in the discussion
1188
01:19:25,186 --> 01:19:28,726
on why it is that we,
and the Universe, exist.
1189
01:19:32,271 --> 01:19:34,809
If we find the answer to that,
1190
01:19:35,146 --> 01:19:39,465
it would be the ultimate
triumph of human reason.
1191
01:19:42,500 --> 01:19:44,612
For then we would know
1192
01:19:45,251 --> 01:19:47,736
the mind of God.