What can you do with the Cadbury's cream egg?

And I thought about it.

I don't want to miss out on this opportunity.

And then I recalled something where the shape of an egg is important in particle physics, and that's in trying to explain why the cosmological constant zero.

So the cosmological constant is a term that's present in Einstein's equations, and its effect is to caused the universe to excite accelerate today.

Until about the mid nineties, we didn't even know the universe was doing this.

The universe we thought was decelerating so that although these Galaxies were moving apart, they're actually slowing down because the force of attraction due to gravity was slowing them down.

And so we were all very happy that this term that could be there, the cosmological constant was actually zero.

It wasn't playing any role but the turn of the 19 nineties, and then towards the end of the 19 nineties, it became clear the universe seems tohave this term, not zero.

It is there, but with a very small value.

Still close to zero.

But a small positive value on the big problem is actually to try and explain this value.

So where does the egg come in?

So in the world of particle physics, one of the approaches that we take is that where we let our imaginations run free and we say, Maybe there's more than four space time dimensions.

We usually think of four.

We think of time on then three, Space X, y and Z.

But in some scenarios, especially those coming from string theory, that can be as many as 10 on duh.

But a simpler version that has been put forward, a toy model, really not to try and really explain that the universe.

But to try and get some of the features of the extra dimension is one where there are six that's called the six dimensional gauged Kyrill super gravity model.

All the countries like model, so that's perhaps what they should have called them.

Because, of course, they're extra dimensions.

So here's my hand.

Here's my hand is representing the four space time dimensions that we that we live in, that we perceive.

Of course, I've I've had to get rid of two of them because I've only got two here, so I've got rid of a time, and I've got rid of a position for every point on this surface, which is called a brain.

Every point on this surface there is another two dimensions coming out instead of the universe being four dimensional.

In other words, you have Time, X, Y and Zed.

I'd have two more coordinates I could call them.

They typically called Roe and Theater.

On these extra to coordinates are every place in the universe.

There's six coordinates explaining that particular point.

So here, at this point here that also be these two extra dimensions.

Coming out with a particular value of row in a particular value of theater on bro takes me from this end of the egg to that end of the egg, and feta takes me around the egg, so those are the extra coordinates.

So the importance of the egg shaped as opposed to Ah, a soccer ball, which is ah, sphere, is that there's a particular curvature associating with this egg a particular way that it's curved around.

And it's that particular shape, which allows the energy associated with that curve space to cancel out the cosmological constant, leaving me with zero cosmological constant in the four dimensions on.

Then what?

I then uses quantum mechanics to generate a very small cosmological constant.

But the key ingredient of the egg is that it actually provides me with a nice mechanism to cancel out the underlying cosmological constant.

Leave me with zero on the on the four dimensions that we live in on.

Then what I can use is the world of quantum mechanics to actually generate a very small cosmological constant.

We haven't yet solved that properly.

Their step that's still going on, the cosmological constant problem.

You know why the universe has the value it has for the cosmology of Constant still remains one of the the big problems in theoretical physics.

In order for the cancellation to a care you can actually work out.

And so Kara the right value and then to give me the masses of the particles that we see, you can work out what the typical size of this egg would be, and the typical size of this angle, or of the extra dimensions is about 10 microns.

That's really big.

Remember that the the size of an atom is about an angstrom that's 10 to the minus 10 meters.

This is about 10 to the minus five meters, so it's easily within the range that we can see.

So why have we had not ruled this act egg idea out already?

So the reason this hasn't yet been ruled out is that the forces of niche that we experience, that's a strong force, the weak force, the electromagnetic forces.

They are all confined to live on the brain.

They can't proper get into this extra dimension in particularly electromagnetism count.

So light count light can't get into this extra, they mentioned.

The only force that's left that we're aware of that can get into the extra dimension is gravity on.

It leaks from the brain into the extra dimensions.

So we'll have to probe for this extra dimension through gravitational effects on the constraints on these models from gravity, a very weak And so, believe it or not, it is possible that they could be an extra dimension.

A rounders that has a scale of about 50 microns on.

We haven't yet detected it.

You guys are pretty good at measuring gravity.

You you know you guys measure gravity all the time.

In the course of your work, why wouldn't you be able to measure this seeping gravity, which is escaping out into the eggs?

Because it's such a weak force, So gravity is is a very weak interaction and that this is one of the explanations.

Actually, White is weak that some of its sleeping out on DDE.

What we're left with is the gravity in in the brain.