At the moment I'm working on graphene, graphene, transistors and enjoying that.

But whenever I have a holiday or a weekend, especially a rainy weekend or rainy bank holiday, I start reading books about cosmology.

I've just been reading the proceedings of Ah, bunch of conferences.

Well, we think about our universe has consisting off our planet, of course, going around the solar system the solar system being centered on the sun and the sun being a fairly modest star in our galaxy on galaxy can contain something like a boat.

If I remember correctly, something like nearly 100 billion stars We see that is the Milky Way, of course.

And then the night sky If we know where to look and I've got a sharp eyes in the sky is dark, we can see the another galaxy like ours That's the Andromeda galaxy on.

In fact, the Andromeda Galaxy and our galaxy called the Milky Way are parts of our group of Galaxies, our local group of Galaxies on.

Then if we look further out with big telescopes, we could see more and more distant Galaxies.

Bottom of hell going back to when the universe was much, much younger.

Because, of course, it takes time for, like to get from those very distant Galaxies to us.

And so we're seeing our universe in a much earlier stage.

But there are ideas with the this idea off that the universe is now expanding due to the presence off the dark energy.

Or if you would call it the cosmological constant, that that was Einstein's biggest blunder.

I think we've done some stuff on that already in 60 symbols and so on.

The idea off this space expanding and in particular, the very rapid expansion of space in inflation in the very, very early stages of our universe.

This idea of inflation has led to the idea that other inflation's can happen beyond our own observable universe.

So we got other universes blowing up on there.

Maybe on infinite number of these on, they may be quite different from the universe in which we live on DDE.

That means different in the sense that wealth of extreme example they may may not contain electrons and protons, though that's very hard to imagine.

Maybe they would just contain dark matter, which is very mysterious to us.

We have it in our universe, but we don't really know what it is.

It's not like it's not protons and electrons, that's for sure.

So we got that dogmatic you could imagine.

Universe is made after dark matter or maybe just made out of black holes, which where all the matters could kind of be compact, ified and doesn't really exist as electrons anymore.

So that would be a strange universe to us.

So cosmologists are suggesting we are only one off a large and possibly an infinite number off other universes and that who'll subset is sometimes called the multi verse, though of course the universe should contain everything but yeah, but universe.

But the motive.

It's a very clever name that there are lots of universes out there on dhe, probably at least with, you know, with our present understanding of physics and without experiment techniques telescopes.

We have no possibility at all of ever knowing anything about these universes.

So people then argue hard core physicists would then argue.

I think that well, if we can ever chance them so they're outside science because we can't do any experiments with them.

But of course, you can't really do very many experiments with pretty much all of our universe.

We can only observe it, but we observing it is sufficient for us to get our information about it.

So the most recent discovery being the discovery of dark energy, which is causing the universe apparently to expand at an ever increasing rate?

There's a wonderful chapter in the book I mentioned by Martin Reese, where he describes what he calls an aversion therapy that if you're afraid off Big Durant alors, then you start off putting a little spider in hand and then a bigger one.

Eventually, you know, you might be able to put up with a Trenton on your hand something like that on Dhe the I think he's quite enamored with the idea of multi verses.

In fact, I guess he's one of the big proponents of it.

Um, on his idea is that it is quite a valid point that he makes.

Is that a time off?

Before Galileo, we had a much more restricted view of the universe before him were, you know, there's a whole period for a couple of 1000 years that we thought that the Earth was the center of the universe on then experimental observational astronomy started and people took a more enlightened view.

And we had a healer centric view of the universe.

People like Kepler and so on and Newton built on that.

But even so at that period, even until large telescopes were made when we were no idea of what Galaxies were, so we were very much restricted to to something perhaps a bit bigger than the solar system with solar system, all the nearby stars.

But eventually we realized there were other Galaxies beyond us.

But of course I already mentioned the point that if we have with our biggest telescopes way, we simply were probably if we made telescopes a bit bigger, we be ableto probe further back in time towards near to the Big Bang and see more distant Galaxies.

They just too far away the moon because they too dim for us to see properly.

So we could imagine at the moment that we're limited.

We simply can't see those Galaxies because they too dim, but they still exist.

And they consistent with a model that we've developed.

No, but of course, at the present time, even if we could suddenly spend tens of billions of lone but rather wasting and all these other stupid projects, like, uh, wind wind turbines, for example, your baby, or to invest it in big telescopes And then we could probe probed deeper.

But even then, even with bigger telescopes, they would be parts of our universe that we could not observe.

But simply because not enough time has elapsed for the light to travel from those distant and an observable Galaxies to reach us by the present time.

But if we wait for another 50 years, we'll see a few more.

We wait another 100 years.

So again, those are part.

Those are subjects of physics, and it's perfectly reasonable.

This is Reese is idea that you can use this aversion therapy and probe deeper and deeper and even think about things you haven't seen yet.

Well, that that's that's probably probably right, but but we could we could ask questions about because we know something about the creation of our universe.

We think we understand that pretty well.

Now there's a big bang and way had inflation on gravity started slowing everything down, and then we realized that the cosmological constant is there is.

Well, it wasn't I.

Stein's biggest blunder after all.

He introduced it on.

They need to say you didn't want it, but now it does look as if there's that.

That or something like it is causing the accelerated expansion of the universe.

You always seemed to me like quite practical scientist, You like you like experiments.

You like the hands on stuff you like evidence.

Why do these multi versus capture your imagination so much when these things there's no experiment?

Well, I think people will be watching these pros.

They know about my obsession with the fight structure constant, which is one of the fundamental constants of nature.

And, of course, the fine structure constant.

Shall I write it down?

This is equal to the square of the charge of the electron over four pi.

Absolute north.

This is this bit is pretty boring.

And I could combine it with that so I'll just put their own brackets.

But it should be there in the S I units that we employ.

And then we got planks constant.

Then we've got C in the denominator on the value of this is we, though, is 137.359 nine and then I can't remember doesn't go the nines forever.

But something like that, but to a good approximation, is one of 137 that fine structure cost is telling us the ratio between the strength of the electric charge on planks constant, the other import.

Interesting, constant.

We take the mass of the proton and divide that by the mass of the electron.

That gives me another constant, which is 18 136.1 fight, I think, Dr Not so That's very important now.

Both of these Constance the Big toe have chemistry as we understand it in biochemistry and maybe even life as we understand it.

The values of those constants are quite important now.

There's some other constants, of course, that are very important as well.

There's gravity now.

It's not the gravity on the surface of the earth, which is just 9.8 times 9.8 meters per second per second.

It's big G or Newton's constant, which is much more general, in which we can apply not just the gravity on the earth, but you know, the gravitational pull between the between the Earth and the moon and the policies son on the Earth.

So Big G's another very important constant, and they're a bunch of other constants in the fine structure.

Constant is is the constant relating to electrical charges electromagnetism.

But there are other forces in H like the weak interaction.

So the week fine structure constant is a well, a weak interaction find structure constant on the things that hold strong forces that hold nuclear together and the quarks and the blue ones, and so on.

Things that make the protons we got the strong force as well.

So we've got in addition to that we got off a week.

We've got off a strong interaction on their various other things that parameters that we have to put into the standard model of particle physics and then the other one I'd like to write down.

So if we look at all of these, the other one is the cosmological constant, which is self is very interesting.

On that is the thing that the astronomers have discovered by looking at the supernova in very distant Galaxies.

They from this they deduced that the university is beginning to expand away on getting blackboard more rapidly expanding as well, because this thing will eventually overpower the gravitational attraction that has been tending to hold back the universe since the time of the Big Bang.

So we got a whole suite of Constance.

No, I haven't written them all down.

But there's the electrical fine structure.

Constant.

Let me put me on that electromagnets.

I should put electromagnetism fine structure, constant.

So that's the electromagnetic fine structure constant, which, by the way, does change with energy and length scale.

That's just it's low energy value.

We've got the proton to electron mass ratio.

We've got Big G.

Newton's constant we should.

Tim is the strength of gravity, and we've got the cosmological constant.

And we've got these other Constance for the strong weak interaction on other parameters in the standard.

So we got all these.

We know them on you can you can look up a standards text book and look up their values.

And there they are, you know, universe.

Now, of course, the fascinating idea about but is, well, fascinating personally idea in our universe is wide of the Constance, have the value that is that we have they have on we don't have.

We don't really have a theory for that.

I mean, we can work out the Proton electron mass ratio by putting in the parameters of the standard model.

But we've, you know, those pragmatism feel like that.

We just have to deduce them from measurement.

Most importantly, they are very, very important for the existence of life, for the existence of rocky planets and stars and so on.

They've got values which were quite critical to that on then, for the synthesis off larger nuclear, atomic nuclear in stars.

They're important for that and even the synthesis of heavy elements in the Big Bang important that it's all of these things.

They really determined that the universe in which we live.

So then you can ask the question that if there are other universes out, there are those values constant and according to string theory, which I don't ask me There we got string expose you here you could go talk about.

But according to string theory, those constants could be different in a different big bang scenario.

In another universe on a SWAT, as I can tell what I've read, it's perfectly possible that some of these particles that are really important to us might not even exist in another universe.

There's another is also very interesting about the cosmological constant, which is fascinating.

We've only known it's there, really, for the last experimentally for the last decade on, some smart theoreticians were talking about it.

Of course, Einstein dreamt it up, but we didn't really know how big or how small it was on.

It turns out, of course, to be worryingly, extremely worryingly small, because if you do a back of the envelope calculation of work out, what the energy of the vacuum is, this pressure that's pushing the University of the University apart.

The unit.

If we Sorry, I always say university, because if we do, ah, back of the envelope calculation to estimate what the strength off the cosmological constant.

Or perhaps I should say more strictly the dark energy, which is kind of equivalent to it.

The back of the envelope calculation gives us on, sir.

That's the biggest miscalculation in all of science because it's not out by a factor of 10 or a factor 100 or 1000 which is 10 to the third or 10,000 which extended forth that back.

The envelope calculation is out by a factor of 10 to the power 120.

Now you can massage that down to value smaller values, maybe 10 to the 60 by doing so different theories.

But basically we do not know why it has the value that it has because of the present.

Time is actually fairly close to the density, all the rest of stuff, ordinary matter like us and the dark matter.

But it's also just about the value that it has is just about big enough for us to observe it at the present time, using our present technology that seems, that seems so.

It's a kind of double.

Why is it so small that it's rather screen just got the value that it has for us to observe right now?

But there we are, So nobody really knows why.

It has the value it as which brings me back to the motive er's, because in other universes within this multi verse, the cosmological constant or the dark energy could be much bigger, so the universe will rip apart even before Galaxies have time to form.

Even before stars have time to form.

So no stars, no planets, no Galaxies would be no us on.

You know, that would be a universe which we would find very hard.

Think off in terms of life existing.

So that's an interesting thing that could could be different on if the fine structure constant or the Proton electron mass ratio were different then you know way wouldn't have the kind of universe that we've got.

If the strong interaction would be too strong, you'd have die protons falling, for example, rather than having the types of atomic nuclear that we have in our universe.