This is the question of where do these high energy cosmic rays that bombarding the earth?

Where do they come from?

Basically, we've known about it for about 100 years.

Exactly 101 years, to be precise.

There was a guy called Hess who was flown around in a hot air balloon, and he noticed there was some radiation hitting him.

He detected this radiation, and it's basically very, very high energy protons.

They're just coming from somewhere, and they're hitting the earth.

And, uh, we really didn't know where they came from.

Super super high energy.

Far, far in excess of any kind of proton that's flying around the L H C, for example.

So, for example, at the l.

A C protons have around.

But when it's a full work, which it will be once it starts up again.

What caught seven TV of energy?

That pro TEM So, which is a lot?

TV stands for air terror Electron volts.

That's 10 to 12 electron volts on basically the ones that the high energy cosmic rays that were coming from outer space, the highest ones have been about 300 million TV.

So an awful lot more to get a pitch of how much energy is installed in those highest energy cosmic rays.

If I were, like wack a tennis ball like you Brady 100 miles an hour, the counter speeds that you know the top plays Andy Murray's of this world a serving up.

That's the kind of energy we're talking about, what is packed into a single proton.

But actually, when it comes to smack in the earth that most men would just pass straight through, the earth isn't dancing off.

Most cosmic rays come through the atmosphere, come past us, go through the earth, go through the core of the earth, come out the other side and keep going through space.

Yeah, mostly, we'll pass straight through.

That's correct.

Here was amazing.

Yeah, where the questions is.

So So why do we not know where these things are coming from?

We know they're special.

Very sophisticate.

We've known about these things for 100 years now.

Why did we not know where they come from?

The problem is, is these guys have charged okay?

The protons that charged so charged particles get moved around in magnetic fields.

There was a lot magnetic fields out there in the galaxy and beyond.

So let let's say right.

I have some crazy magnetic field going on in this room, and it's a protons in outside the room and, you know, it comes through the door, it gets moved around the magnetic field, twists it all the way around, and it goes smack straight into your face.

Brady, which director did it come from?

Well, I'm gonna think you can absolutely.

You think it came from that way?

But didn't.

It was hiding outside the room before you even started this this video.

So we throw up their hands in the air and say, We're never gonna No, no, of course we don't do that.

We find other ways thio work out where it came from.

There was an idea Go.

That's really dates back to a guy called Fermi.

And interestingly enough, the satellite which which has made the observations which have led, said the discovery that was announced today is also called the Fermi Satellites.

It's a nice coincidence.

Very these ideas go back to filming.

What he suggested was that when a star dies in a supernova.

When a star reaches the end of its life, it runs out of fuel in certain situations that could go supernova.

One of the things that happens when a supernova is that you send out a shockwave.

Okay?

It's very, very powerful Shockwave.

It basically happens because the star tries to collapse and then it gets.

The collapse is sort of jolted by the neutrons in the star, not wanting to be put to close together.

You get this shop air sort of abrupt halt in the collapse and that causes the shock wave will hit this evening in a second.

That's what a supernova is essentially.

Anyway, we have the shockwave.

Do you have a situation where you have a proton which is moving around in the magnetic field surrounding this dying star?

Okay, so it's moving around the magnetic field.

Every so often it passes the shock front when it passes.

That shock front gets a kick from the shock, okay, gets a kick from the shock and it gets ah, accelerated a bit and then it moves around a bit more going all higgledy piggledy directions because of this magnetic field.

Eventually it passes the shock front again, and it picks up more, gets more of a kick.

More kinetic energy each time it picks about 1% of its kinetic energy, increases it by about 1%.

So it's getting more and more and more and more energetic eventually gets so energetic that it escapes.

This is the idea.

This might be the source of of, of high energy cosmic rays.

So we start looking at things.

Objects like that.

What might we see?

So we look at it, let's look a supernova.

And that's what might we see on a particularly looked at two particular supernova.

They got typical astronomers names it.

I'm not going to be one of those called the Jellyfish Head Nebula today, So that's quite a police.

You can remember that the both of the order of 14,000 light years away.

So the faraway objects, these guys going super never.

So this should be if this effect is correct.

High energy, cosmic rays coming from there.

We're not going to see the protons going from that because they've moved around so much.

But what we can see of photons because photons don't move around in a magnetic field.

Unlike cosmic rays game, Aries traveled to a street from their sources.

In particular, If you've got a proton, one of these really high energy protons, what it will do is if there's interest Alan sort of dust around some interstellar gas cloud or something around this, this remnants of this supernova.

When the high energy proton hits another proton, that's lower energy.

But sitting in this cloud, then basically what will happen is it can produce what's called a pile.

This neutral pion is just is a combination of clogs in case it can produce this power.

And then that pie on convict K into two photons and they'll be high energy photons on those are the things that we see on.

Those are the things that would come direct to us from this supernova.

Now the important point is, is that these photons that come from this process have a minimum energy and the reason they have minimum engines because they were produced by the pilot itself, right?

So they at least picking up the energy, which is essentially the rest mass of the pie, on which is about 135 g e v Giga Electron volts.

If this affect, this correctly, would expect to see the sort of drop in the number of photons around 150 130 g ve.

Because basically not producing them from these pile on the case anymore.

And so that's what they look for.

And that's what they saw.

It's not the end of the story ready.

It's so we say we've made so maybe okay, we think this is where it looks like.

This is where these high energy guys are coming from.

Is it the end?

But there is another mystery, and that's that.

There's something called G, said K cut off.

And this basically says that this should be maximum energy that any high energy cosmic ray could have.

All right, now it's about 50 million TV.

Remember I said there were once about 300 million TV, so it's a little It's not hugely more so.

One could say it's a bit blurry, but it's like six times Well, yeah, that's six times in chronological terms and so bad, is it?

So it's a little bit more, but okay, so why is there a maximum amount that we expect right the reason is you take one of these very high energy protons.

It's going.

It's officially Hi, Andries.

It will start to interact with the cosmic microwave background radiation itself.

Right?

And you get a process whereby again pylons the proton interacts with the cosmic microwave background photons you produce a pie on.

So you lose your energy into these piles, okay?

And then they decay into other photons.

But but the point is that protons themselves would lose energy into these parents.

So you basically get it.

Reach a maximum where you say, right.

If the protons got too much energy, it will just start losing them into pylons and end of story stop.

You shouldn't say anything about that scale.

We do see some.

Is it really a mystery?

Will, You know, I think I think the jury's still out on that.