A Friday afternoon experiment.

We thought we would just suspend this thing on, then prick it with a sharp knife.

Friday afternoon experiment is an experiment.

You do when you've got you've got an idea for something that may work may be a bit crazy here.

Two of my colleagues, John Middleton on the left, on Olive McCroskey on the right.

One, two, three.

He's just pissed the balloon may just burst it so you could see immediately the skin of the balloon peels back on, releases the water.

So the because this bond number is so large, the water is gonna drop under gravity.

So yes.

So at this point, I joined in the fun on dhe.

I've been playing around in my research with putting high voltages on water droppers two, in fact, to get them to bursts or a water droplet.

If you put a large enough electrostatic charge on a water droplet, electrostatic forces between the charges are competing with surface tension.

So those charges wanting to essentially get away from each other and expand the shape of the droplet and above a critical amount of charge amount of electric electric charge on the droplets, the droplet will burst.

We had this big voltage source in the lab, so I just wanted what happens if we put 30,000 volts onto a big globe of water?

It is exactly a Friday afternoon experiment.

What's gonna happen if we poke this with 30,000 volts and just just watch what happens under high speed camera?

So there's 25,000 volts on the end of that scalpel blade and I'm holding.

I'm holding the other end with some gloves on, holding it well back.

I don't want to get a belt off.

This electric field at that very sharp tip gets large enough that it starts stripping the electrons off the molecules, the air molecules, and it starts what's called ionizing the air.

So the air becomes electrically conductive.

And this is where you see a spark on DDE.

In this case, although you can't see it on this on this video, there is a little spark between the between the scalpel blade on the balloon and you can actually hear it in here is wine is a kind of squealing noise, Theo on That's the air breaking down.

This is the noise is starting to heat up the air and its fight, causing the air to vibrate and causing air to scream effectively.

So then he goes back.

We didn't really expect the big mass of water to fishing because it's too much.

We need a much larger voltage to get the big, massive water to split.

What we wanted to find was what happened to the little droplets with the little droplets have enough charge on them to start fishing themselves.

But he does look like the small droplets are moving away quicker from the big, massive water in this case than they are with the UN charged case.

And this is because the big droplet has a charge on it.

The little droplets have the like charge.

It's in this case is a positive charge on the big droplets and the positive charge on the little droplets so that positive charges repelling and it's causing their little droplets to accelerate away from the big mass of water.

Okay.

Yep.

Yeah, you see melting.

So in this case, I remember having to, uh, to jab the balloon quite hard.

So I was poking it.

I'm getting some resistance from the scalpel blade.

But the balloon didn't burst at the point of the scalpel blade, quite peculiarly in this case.

So what happens is so as I was pushing the scalpel blade into the rubber, this is what happens.

Bang.

So it breaks from the top.

This time it breaks from the point where it's been tied up with string and then finally breaks on the point of the scalpel blade.

And it forms this kind of really beautiful looking, sort of like mushrooms structural, a jellyfish type shape.

So what we think is happening in this case is that they're made contact with the balloon with a scalpel.

So the balloon is charging up, and at this point there's a large electric field developing, so you get a large electric fields where there's a sharp point.

So we're getting some electric current now through the top part of this balloon just through this string of the balloon, and the string was a little bit wet by this point.

I think this is what happens.

This is the electric current that bursting the balloon got a big electric field at the top, and it's bursting the balloon at this point.

Now, this is where the highest electric field is.

On that balloon you get the highest electric fields where there's a sharp point.

What happens now is that then that unlike the other, the previous case what happens is that this the top part of the water here inside the balloon is then accelerated by the breaking balloon.

You see being accelerated hard down towards the rest of the water, causing these fantastic ripples these waves on the surface.

And then this is continuing out down.

So the water that we've accelerated at the top from the balloon bursting this way you're accelerating out towards the bottom and creating this great mushroom effect.

It is good fun on DA guess something we quite would have wanted t kind of repeat this several times to make sure this is repeatable phenomenon way repeated it twice.

Probably the charge may well have had some influence.

The charge went to the top.

That traditional strain on the on the balloon of the top, of course, is that top is bearing all the weight on dhe.

So perhaps that the weight combined with a charge on the strong electric fields, the top, causing a fracture there on.

Then bang goes.

And this is get this beautiful wave coming down through the balloon.

This top part is accelerating hard now compared to the rest in the water, and it comes straight through the bottom.

That's even better.

That's that's fantastic.

This shape we took precautions, by the way, we're charging this, that Richard Hill was wearing a pair of rubber gloves and over that he had felt gloves and he was standing also on a good insulator, because by the time we're breaking these balloons, they look quite a lot of water on the floor.

I got two experiments now in which we've done bursting the balloon with high voltage with charge.

So now you want to see what happens without charge.

So this is kind of this is the sort of scientific method we're now starting to see what variables were involved without charge.

I'm having to stab the balloon quite hard.

I remember having to poke the balloon pretty pretty hard on it bursts not at the top, as with the charge.

So we're not getting this big electric field.

You've got no charge on it now bursting in quite a different way.

Now the balloon the water is just is falling is one big mass.

It's not forming this kind of jellyfish shape anymore.

We had a relatively small amount of time to do the experiments, so we're trying to get data.

But just to see that mushroom thing being reproduced twice, I think we could try and follow that up.

Known.

Understand it better.

We got some reproducible results is a beautiful shape.

It's rather elegant.

So can we know?

Just use the simple equations of hydrodynamics and explain that habia including the charge, of course and gravity.

It's a very nice result.

I'm totally unexpected point that way that sharp if you just come in from the side when you think it's a good build momentum.

So now, now we're just trying everything that we can try.

We've got a few minutes left with Brady and his high speed cameras, so we just want to try something.

Just don't try anything, so the next thing we try is spinning it.

We want to spin up the water and see if we've got If you got some water with spinning round, it's got some angular momentum before it bursts.

What happens as it's gonna burst?

So we've drawn some marks on the surface of the balloon here so that when we play the video back, we can work out how fast the balloon is spinning.

So yes.

So we've got a little picture of Lawrence there as well.

Thio, use the mark.

We're working out how fast the balloon is spinning.

We've been doing work on spitting in our levitation system.

We'd be doing work on spinning water droplets.

And that turned out to be quite interesting because as we spend up the droplet, the shape of the drop of changes from spherical to festival, something like the rugby rugby ball.

If you like American football on, then it forms a sort of a three cornered hat shape.

The physics of this has been studied from a theoretical point of view for over 100 years, and they're being experiments up in the space station on spinning droplets.

But it turned out as well that the results were some interest to black hold physicists because black holes have this.

Several properties got mass charge on dhe angle momentum.

What we've thought to do it is a very crude experiment so that the problem is, you know, inside that Blue's got a lot of water.

It's got a fairly large mass.

In the time we had, How could we spin it up?

Well, the obvious thing to do is to turn the blue around, around around and twisted.

We prick it without without blade again and just to see what happens.

Okay, I know what happened in there, saying, See, it was rotating fairly rapidly at this point.

About one revolution a second, I think I seem to remember.

So is rotating quite fast.

It just doesn't look so fast on the high speed camera, so it still is still spinning.

It's hard to see if there's much difference, stupid it to the other one to go on.

Is it a kind of a cavity there where have stabbed it?

And I suppose it does form a sort of slightly different shape to the one that was stationary.

Starting the water is becoming its flying out on the action of the centripetal force or the centrifugal force, depending on what you reference frame is, so you want to try it again.

We want to see if it's reproducible, not just some kind of worn off some fluke of the experiment.

So here's Lawrence.

We're trying it again.

Yeah, he's kind of testing the waste of it to see, see if the string at the top would hold the way to the balloon thing, but now becomes not an experiment in physics.

This becomes an experiment in biology to see what the reaction time of a human human being is now.

I wasn't bones.

I was just trying to see what could if it would hold under its own weight.

Yeah, he's going to start stepping back any second now, so he's starting.

The messages got through to his head, and now he's going to get very wet any second now.

I think he's still not realized very year, so he's just now starting to step back.

So this good 12 seconds after the balloons burst, the messages got through through the from his eyes into his brain.

And now now it's certain the message to the rest of his body to move away because he's gonna get wet.

I'm not sure my reaction times would be any better than that.

I think that's pretty good reaction time now I see the pictures again sitting down at the desk yet, so it's so clear that we ought to repeat it.

But maybe we could have to come back to you and get you to do a bit more filming.

Be great.

We could write a paper together instead of doing these YouTube videos as well as doing these YouTube videos.

Of course you will break you.

You'd be probably the harried goes before Hill.

Maybe you help us, right?

You could be first author.

He's Oh, yeah, I know, but no way baby ought to figure it out before we argue.

But authorship?

That's always right, Tonto.