So?

So for the next few minutes, I'm gonna talk about literally nothing to talk about the vacuum, void nothingness and have scientists really, really need a vacuum.

Need something that's empty off molecules to do a lot of experiments is very, very important for the work we do, where you want to manipulate individual atoms and molecules.

You wanna keep it in a vacuum on.

Make sure that you've got a few molecules sort of contaminant.

Molecules interacting are bonding to the surface as you can, however, you can never, ever reach our perfect vacuum.

And that's related fundamentally again to quantum mechanics.

The unit we use for pressure while you re interview units were actually one of the interesting ones.

His tour, which stems from Torricelli and Torricelli, was one of the first people to build.

It was the first person to build a barometer on 760.

Tour is the is.

The atmospheric pressure on that stems from certain extent stems from the height off a column of mercury that atmospheric pressure can actually sustain.

The other unit we use is the Mili Bar, which is perhaps more familiar, but the unit that the s I u nit a proper aside unit, Mrs.

In terms of Newtons per meter squared is the Pascal on DSO Atmospheric pressure is 10 to the 500,000 very roughly 10 to the five Pascal.

But when I just told that number that 100,000 Pascal that that's just a number It doesn't really make a mean a lot, but if we think about what that actually means in terms off force on the force on an area, it's a huge force.

100,000 newtons per meter squared is equivalent to about a Thanh of force on on an area which is about a foot square.

A huge huge amount of force was raining down on us on.

We forget.

Just I guess we're just so used t living with that.

We forget how much force that can actually in part.

So the vacuum in a vacuum cleaner compared to the experiments where you do is just terrible, useless nonsense.

We couldn't do anything without type of vacuum.

Turns out that the vacuum in a vacuum cleaner if we start off with atmospheric pressure off about 100,000 pascal, the vacuum in a vacuum cleaner is roughly something like 70 or 80,000.

Pascal's are not a very, very big change.

The key thing there is, though.

What's happening is that sometimes you get this idea that when we use a vacuum cleaner, that's something it's sort sort of actively sucking.

The more important thing is that what you've got is a Rh pressure.

That is, it's the force of the off off the air streaming into a region where the reason aware the amount of air has been reduced.

That actually gives you that force that allows you to clean the dust isn't suck into a vacuum pushed it's effectively pushed in.

Yet it's in trend with the air, something called viscous flows.

Or it gets in trend with the air, and it's it's basically pushing it.

It's driven along with the air.

So this idea of sucking is is actually not quite what's happening on a pretty vivid demonstration of that later on.

We really want to work at not 100,000 Pascal or 80,000 Pasqua.

We're actually gonna go down and work a Nano Pascal pressures so 10 to the minus nine of a past that I'm not the pressure we work with in the lab.

You know, your routine experiments is comparable to that You actually get in the surface of the moon.

So we want to remove all those molecules that can get down to those type of pressures.

Right.

So what we have here is a tube, which I'm about to evacuate.

We talked earlier about just how much force air on air pressure can impart.

Hopefully, we're going to be quite a dramatic illustration of that.

The woman he was gonna pump the air out of this pipe with a rotary pump vacuum pump in here.

There's a ping Pong ball.

I've got a very simple seal here in a very simple seal here.

The seal on this end is just the end of Ah, plastic cup.

You put that on there that's gonna be held in place, busy by the air.

Pressure will be a document and pressure illness on this side.

I just taped it up with some tips.

The pump, it, I've I'm gonna leave it for a few seconds, and then I'm gonna put a Stanley knife, rupture the sale at the back here.

The air will rush in on the ping Pong ball will go flying at the end.

If we do this right, the Ping Pong ball should fly out at about 400 miles an hour.

Something like that.

Hopefully will pulverize the court can, Right?

Let's try.

Yes, so good.

So let's see what it did but certainly pulverize the cold.

Come on.

In fact, with a longer leant on a bit more room, few political straight through the cold you should take from that The rather large forces that air alone can actually impart that said that bald.

It's a Ping pong board.

I don't know.

It didn't go in the bin, did it?

Ah, that's fantastic.

Actually, in this case, it hasn't been The ping Pong ball has been damaged, but that's a standard ping pong.

Tennis balls, tennis table, tennis ball, 40 millimeters diameter.

Very, very, very light with And it ended up in, up in and it pulverized a cocoa.

So that's their force.

That air pressure along can actually exert a really nice way of looking at vacuums are getting getting a good insight into what a vacuum is to look at something called the mean free part.

How far can a particle get before on average before it smacks into another particle on in a Thomas Feyerick, pressure turns out to be a very, very, very small distance.

It's about 100 nanometers, so on average on air molecule in the air can only travel about 100 nanometers.

Ah, 100 billions off a major before it smacks into another one.

When we get down to really, really little precious, like 10 to the minus nine and nano particle, which is what we worked with in the lab with pressure on the moon, then what we have is a mean free path that is many thousands off kilometers.

So those those molecules have a very, very lonely journey through through through the void before they actually binds into another molecule.

It's amazing from one perspective that we can get down to those pressures, but the amount of pin sometimes that's involved in trying to get our experiment equipment to get down to those pressures can be quite tricky.

For example, one of the things we have to do with our standard state vacuum chambers to get down to those pressures, regardless of sort of the quality of the pumping we use, is we have to bake them well, it'll have to put them in an open on dhe.

Cover them all of 10 phone.

Make them nice and toasty.

Andi bring the temperature up to about 150 degrees.

And the reason we have to do that is because if we don't do that, all the water that's in that covers all the surfaces in there.

There's a thin water.

Film just sits there on over course of time.

Just gradually, those water molecules come out and pollute our vacuum business.

You have to get rid of all those molecules.

Okay, let's have another go.

Better vacuum buildup on now.

Let's try.

Yes, yes, that was good.

Oh, it's shattered.

A bit of it.

We're getting close to it.