You're giving the talk, eh?

It's nerve racking Stevens there.

You're talking about things.

I was told about cosmic strings, and he'd worked on these.

Andi, I was thinking, I wonder what he's thinking.

And then you hear the click Click your thinking on his fountain era is that steak or he's going to say, This is rubbish and you've got to sort of carry on and you stop and then the organizer carry on, It's OK and you carry on.

And then it's not that he puts his hand, apparently can't do that.

So just that the speaker turns on and outcomes these words, and I was okay.

It was a question.

I had an idea of the answer to the question, and so but that feeling of has discovered something or not.

That is wrong.

Very well.

In some sense.

It is a sad day, but actually in other ways, it's a triumph in that, given that he was given a couple of years to live in the 19 sixties, the fact that he made it into his seventies is a truly amazing a demon He was so determined to succeed, so determined to keep alive.

I mean, he was told he should be dead within whilst he was doing his PhD.

And along the way he did all this truly astounding physics, which you know, for somebody with no disability, it all would have been an amazing achievement.

But to do that from wheelchair without access to you know, when I'm thinking about something, I've often scribble something on a piece of paper or I'll just fiddle around with things.

Not being able to do that having to do the whole thing essentially in your head is a truly astounding achievement.

So I think probably the main thing to be doing today is sort of celebrating a truly exceptional and completely unlikely life.

So packing what he did and to make the contributions that he has is just staggering.

But is a huge loss.

You can tell from the coverage.

He was a very charismatic individual.

I actually only met him once, so I met him when I was an undergraduate.

So back in the 19 eighties, before he lost his voice.

So I I heard him give a talk in his own voice.

Even then, the disease had progressed to a point where he couldn't talk clearly on.

So he actually had one of his PhD students along with him, who was kind of interpreting what he was saying.

So he was giving the talk, and then the student was sort of repeating what he was saying so that people who weren't kind of tuned into being able to understand what he was saying could hear the talk as well.

To be honest, I remember absolutely nothing about the content of the talk itself.

But I do remember Stephen Hawking and it really it wasn't just the fact that he was somebody in a wheelchair who was hard to understand who was saying all these amazing things.

There was something about him that kind of did have that sort of charismatic personality.

Yes, whether it be from his book, of course, Brief History of Time, which I think is sold 20 million copies through to the lectures he gave through to the broadcasting, gave his media contributions his efforts with the National Health Service, you know, supporting that he touched everything on people.

Listen to him.

They wanted to let's just described a couple of the things right because they're just so extraordinary what he did from his PhD days, where he, he I think, was influenced by Roger Penrose that Roger Penrose, who was also a genius but working on general relativity on dhe hawking on Penrose, realized that if you thought of our universes containing sort of ordinary matter, that kind of things that you and I are made off on, that that matter would evolve in such a way that if you traced it back in time, the universe simply had to have a singularity.

It had to have a region where the space and time diverged.

They had curvature, singularities.

That meant the equations broke down.

So many.

Where's general relativity itself predicted its own demise because the equations brought down Andi.

What Penrose had done was he'd spotted this for black holes on what Hawking did, was he?

He extrapolated it to the universe, and in doing so, he basically showed the universe had toe have at least that this classical picture, what we'd call a big bank where space and time emerged from.

So that was the first major thing he did.

But then he went about trying to address it on Dhe.

He was interested in in black holes.

Naturally, because of this, this type of work on in the seventies he did something quite extraordinary.

He basically brought general relativity, quantum mechanics and, further down that makes together.

And in this mix, he demonstrated that because of the influence of quantum mechanics, that a black hole that we always think of as being black because nothing can escape from it from its event horizon, he demonstrated it mean this must have been such a dramatic calculation to do what I'm about to describe.

He demonstrated that it's not black.

Actually, the black hole has a temperature, and if something's got a temperature, it will radiate.

And it was radiating particles.

So the black hole, because of quantum mechanics, was radiating particles.

It was actually shrinking.

It has revolutionized the world of theoretical physics.

This concept of hawking radiation on there's no question that if they'd have been able to discover it, he'd have got the novel price, just him.

It had been a solo Nobel prize for him, and they haven't found it because a typical star the temperature of this radiation that's being emitted is so low that we can't detect it.

We just a typical style like black hole of a solar mass.

We just can't detect it.

But the the the idea is so firmly rooted in quantum mechanics and relativity that it is accepted that this this will happen, that black holes will evaporate.

In the 19 eighties, he turned his attention back back again to the beginning of the universe.

Andi, he asked the question, You know, Okay, if you knew, assists, got this singularity, what can we do about it?

And he came up with a proposal with another wonderful physicist called Jim Hartle that actually the universe effect.

We didn't have a beginning.

This is called the No Boundary Proposal.

And what he argued was, as I go back in time, So what we would have said was this singular point that that actually the time becomes imaginary and in becoming an imaginary time, it actually affects allows you to round off this singularity, and so there is no boundary.

And so he you would turn this on its head and you say that the universe began from a quantum fluctuation which produced this initial starting point, which then emerged to give our universe today on this is the wave function of the university in quantum mechanics.

We use where functions all the time, to describe positions of particles at different times.

He decided, along with hartal, that there should be aware function describing the universe on.

So you did it and we don't know if it's right that I think Jim and Stephen certainly believed it was right.

People are working on this older time to try and understand it.

But these three areas just transformed our field, even things like his voice, which clearly since that voice synthesizer was created, he could have if he'd wanted to moved over to something, which would have sounded much more naturalistic.

But that was defined him.

But it was actually all that Stephen Hawking on Dhe That's that's kind of unique personality was imprinted in him in all those ways in the way he sounded and the way he looked.

Andi, he traded on.

It is the wrong word.

He no, he used it as a way to present the subject of present science in a way that was sort of accessible of different and made people think about things and threw a whole variety popularly, that you know, the big Bang theory, The Simpsons, you name it.

He was on it at some time or another.

He did something else, which people that are in danger of forgetting it did a couple of things I'd just like to add in.

One is In the 19 79 1980 time early eighties, there was a and on idea called The inflationary Universe emerged with people like Alan Booth and Andrei Linde and Paul Stein hardened Andi Albrecht.

But Hawking was there, hawking Mawson Stewart wrote this fantastic paper on inflation, but in particular at a workshop which hawking helped organize.

Ah, whole group of cosmologists got together and they basically discovered the inflation could give us with the seeds the perturbations which letter?

The structures that we see in the universe.

So Hawking was involved at the ground level here, sorting out the perturbations, we seed the structures of our universe in which seemed to have been confirmed by the beautiful details that we see from the plank cosmic microwave background detector.

So he did that, but he did something else which had forgotten about until today that back in the very early days of his visa research, when he was thinking about black holes, he thought about what happens when two black holes merge together.

Now these black holes have got an area associated with them, and he showed that the area of the combined black hole had to be bigger than the sum of the two smaller black holes.

And that meant he could put a bound on the amount of radiation gravitational waves that could be omitted.

And it's sort of really nice that within the last two years this has been detected precisely.

These gravitational waves have been detected by the lie go detector on dhe from the merger of two black holes on.

They fit beautifully with the ideas of Hawking demonstrating these bounds, which people have tended to forget about.

But he was there thinking about gravitational waves from black holes.

Way before these experiments were done, I was lucky enough to meet him.

I didn't meet him so much in the last few years.

Our past didn't overlap very much, and he wasn't that well.

But in the eighties and nineties, I met him, a lot.

So there's got some happy memories.

I mean, one of them in life in general.

You you have periods of luck and I've had many of them.

And one was that I went to Newcastle to do a Ph.

D.

On um, at the same time a postdoc arrived that someone that's just finished their PhD on that post op was Ian Moss, and Ian Moss was hawking student.

Andi had been working on inflation.

Andi, I think they got so into it that he and had run a bit late with his writing up his PhD.

So he came.

He'd missed the usual job cycle and arrived Thio with us at Newcastle.

Well, he was still working with it with Stephen and Stephen came up within a few weeks or months at least, to give it to give a seminar.

This is so exciting for me, right?

Stephen Hawking coming.

Is it early, 80 82 or 83?

And he came and he gave a similar is it was the time before he he became ill and had to have the tracking up to me.

And so the voice synthesizer you could still speak.

And so for the 1st 20 minutes of the talk, you could listen to him.

He was actually giving the seminar, but such as motor neuron disease is a muscle wasting disease, so his muscles gradually would weaken.

And so his speech would become slurred, at which point the graduate students then took over his graduate students.

But Ian was doing it because he had been his graduate.

Students even finished off the top from, in other words, what would happen.

Steven would speak very quietly.

Ian would be listening, and then Ian would say what Steven was talking about and it was about the wave function of the units.

They just come up with this idea of this wave function describing the whole of the universe.

And so the talk was fantastic.

And then we went to biscuits, and we said to Stephen, where we usually take the seminar speaker for a beer afterwards.

Yeah, okay, well, the beer was down at the key side.

Isn't the Cooper germs down at the bottom of the key side, which is a long way from where the physics department waas.

So we went off off.

We went Steven in his wheelchair.

We went down And for those in the know Newcastle, it's very steep.

So we're coming down this big, steep hill to get to.

The Cooper is stunned into the key side and about 3/4 of the way down.

This, um, even steeper steps on dhe.

We said to Stephen, Well, if you go, you carry on down there just for the path down and we'll just go down these steps.

And he went, No, I'm coming down the steps now.

These were really narrow steps on.

There's loads of them doubted on we're going.

No, no, it's really not Not good.

This And he said, No, I'm going down these steps you're taking May.

We took a corner reach of the wheelchair, and it's a heavy wheelchair on.

We very, very slowly went down the steps with him, and then we carried on and the coop Ridge had another set of steps to get in, and we lifted him in.

And then he said, and it was packed downstairs and people were coming up to him immediately, of course, and even in the eighties he was really well known and they were coming up.

And it's Stephen Hawking having patting on the back and we said, Well, we sometimes go upstairs there, So let's go upstairs.

And so we went up and then he brought us all around and we had it.

We all had a great time with him, and then we all brought him back down again afterwards, and we went back and went to his band so that they could then drive back to Cambridge on The striking thing is, and I think it's sort of sums up what Stephen was was like was this determination, this determination not to let obstacles get in his way on Dhe.

He knew he could have gone down there, but for some reason, which really he wanted to come down these steps and that drive that determination, I think, is says a lot about why he survived as long as he did that ability to just keep going.

It was a great extract time a few years later, when I was look enoughto have a position, and then I would go to Cambridge and give seminars if you had lunch.

A few times when I've been there and I've been I've had lunch and he would just come up and join you because he wanted to chat and he wanted to talk.

And that was that was when that first happened.

I remember thinking It must be no one else around, but no, I just wanted to talk about physics and wonderful man on anti particle, literally pop into existence.

So the particle escapes and the anti particle falls into the black hole.