A Brief History of Time Page #6

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if there were any scientific papers...

that people sent out.

I did discover that despite Hawking's

great brilliance, he does read quite slowly.

I could read

about twice as fast as he.

But of course he would have

to read to remember it...

because it would be very difficult

for him to go back and access the thing...

whereas I could skim the paper

rather quickly and see...

"Is there something

interesting in this?"

If I wanted to work on it,

I could pick the thing up and look at it.

Black hole radiation...

has shown us

that gravitational collapse...

is not as final

as we once thought.

If an astronaut falls

into a black hole...

he will be returned

to the rest of the universe...

in the form of radiation.

Thus, in a sense...

the astronaut will be recycled.

However, it would be

a poor sort of immortality...

because any personal

concept of time...

would come to an end

as he is torn apart...

inside the black hole.

All that would survive...

would be his mass, or energy.

One year,

the Hawkings took me along...

when we went

to a cottage in Wales...

near the River Wye...

and this cottage

was up a hill...

and there was a bit of...

a paved little sidewalk

that went up to the cottage...

which I had not been up,

and of course...

I wanted to do it in the least

number of trips I could imagine...

so we put Stephen's batteries

under his chair...

his wheelchair has space for batteries...

and put extra batteries under there...

which Stephen didn't realize

that I'd put under there...

so he didn't realize his wheelchair

was as heavily laden.

Stephen got quite a bit ahead of me,

and he was turning the corner...

to go around to his house,

but that was on a slope...

so I looked up, and I noticed Stephen's

wheelchair slowly tipping backward.

Of course,

I was about ten meters away...

and tried to run up there,

but I was not able to get there...

rapidly enough before he toppled

backward into the bushes.

So it was

a bit of a shocking sight...

to see this master of gravity

getting overcome...

by the weak gravitational

force of Earth.

One of the worst things for me would be

having people there all the time.

Never alone.

I couldn't bear that.

And yet he finds things funny...

and he enjoys life and he goes

dashing about all over the place...

and I think this is tremendous.

But it's a sort of courage

I haven't got...

and his father hadn't got it,

and we cannot but admire it...

but wonder how on earth

he got it, really.

There must have been

50 people there...

and I was standing off

in a corner...

sort of watching quietly...

for a few minutes, relaxing...

and Stephen was over there,

not far from me.

Jane walked over to Stephen

and looked at him.

He was sitting there

with his head in his lap...

like only Stephen can put

his head in his lap.

And Jane said to Stephen...

"You look miserable, Stephen.

Sit up straight."

Some of your guests

don't understand...

that you're thinking about physics

and having a wonderful time.

"It looks like you're in pain.

Sit up and go talk to your guests."

In 1979...

I was elected

Lucasian Professor of Mathematics.

This is the same chair

once held by Isaac Newton.

They have a big book

which every university teaching officer...

is supposed to sign.

After I had been Lucasian Professor

for about a year...

they realized I had never signed.

So they brought the book

to my office...

and I signed

with some difficulty.

That was the last time

I signed my name.

My interest in the origin

and fate of the universe...

was reawakened

when I attended...

a conference on cosmology

in the Vatican.

Afterwards, we were granted...

an audience with the pope.

He told us

that it was all right...

to study the evolution

of the universe...

after the Big Bang...

but we should not inquire

into the Big Bang itself...

because that was

the moment of creation...

and therefore the work of God.

I was glad

that he did not know...

the subject of the talk

I had just given...

the possibility that the universe

had no beginning...

no moment of creation.

There were theories in the early '70s...

the first type of creation theories...

where the people concerned started off

with a fixed, external space and time...

which for eternity was empty...

and then suddenly, for some

unknown reason, the universe nucleates...

at a particular point

and then, bang, it blows apart.

But the trouble is that when space

and time appear in the classical theory...

that actual point itself

is a singular point in the mathematics.

Mathematics breaks down,

and so...

you cannot use that

to give you a creation theory.

If one goes back in time...

one comes

to the Big Bang singularity...

where the laws

of physics break down.

But there's

another direction of time...

that one can go in

which avoids the singularity.

This is called

the imaginary direction of time.

In imaginary time...

there need not be

any singularities...

which form a beginning

or end to time.

When you come to imaginary time,

you have this rather peculiar possibility...

of having a "now," as it were...

without necessarily having

a sort of a chain...

of past moments.

If we start where we are at the moment

and start running backwards in time...

then for a long time,

things work perfectly normally.

But as you begin to get

further and further back towards...

what would be the origin point

in the conventional real-time picture...

you'd find that

the nature of time changes...

that the imaginary component

becomes more and more prominent...

until what ought to have been the

singular point in the classical theory...

gets smoothed away,

and you have this beautiful picture...

of these bowls where the creation

of the universe is pictures...

of where we are now,

and a smooth bowl of the past...

where there's no initial point,

just a sort of smooth shape.

So long as the universe

had a beginning...

we could suppose

it had a creator.

But if the universe

is completely self-contained...

having no boundary or edge...

it would neither be

created nor destroyed.

It would simply be.

What place, then, for a creator?

All you can really say

is that the universe is...

because it's a self-consistent

mathematical structure.

There's no past because,

unlike the creation-as-a-point scenario...

there's nothing for it

to be created in.

So to say it's created from nothing

is a bit of a misnomer.

It's a misleading use

of the word "nothing".

It's not just that there was empty space in which the

universe appeared, which you might call "nothing".

There was really nothing at all,

because there wasn't even a creation event.

The use of a past tense in a verb

becomes inappropriate in these theories.

Unfortunately, tenses were set up when

people believed in real time, of course...

and we don't yet have a linguistic form

to describe tenses in imaginary time.

The word "time" was not

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