Absolute zero

So Gary and Eunice, they are going to, let's see, I think because Declan was the first one and also has the danger close, I believe, so Icehouse is going to turn and it is going to fire a beam.

This is a new attack you got for being dark and it's called Absolute Zero.

So he's going to turn, and instead of normally shooting the icicles out of his SMGs, it's just going to be a big beam of cold energy.

And you will need to roll me a Weather the Storm for this.

But what if we reduce temperature so much that all particle motion ceases? This state of absolute cold is the zero point in the Kelvin temperature scale, corresponding to -273.15 Celsius.

Many experimental physicists have spent their careers trying to cool things to absolute zero.

Using lasers and magnetic fields, we've now managed to cool certain substances to less than a billionth of a Kelvin.

Doing so has revealed some bizarre quantum states of matter, but quantum mechanics may also prevent us from ever reaching absolute zero.

Understanding the limit to cold will lead us to an understanding of the nature of the quantum vacuum itself.

We're all familiar with the states of matter; solid, liquid, gas.

In these states of matter, particles have an enormous range of individual energies, some moving or vibrating fast, some slow.

Temperature just represents the average kinetic energy of the countless particles.

We've gone through three of the laws of thermodynamics, which leaves just one to go.

And the third law of thermodynamics deals with another strange concept, the idea of a temperature of absolute zero.

We know that temperatures can get very hot and very cold, but not everyone is familiar with the idea of the coldest possible temperature.

However, with our new understanding of heat and temperature, it should make perfect sense.

As the temperature becomes very cold, particles slow to a complete stop, and there is no more kinetic energy.

No more kinetic energy of motion means no more temperature by any real definition of the term.

So we will call this absolute zero.

At absolute zero, every substance would be a solid, even things like hydrogen and helium.

The slower something's molecules are moving, the colder it is.

So we have Fahrenheit, we have Celsius, and we have a third sort of metric we use called Kelvin, and Kelvin stops at zero, and zero Kelvin is that ultimate stillness.

And it's actually, like, physically impossible to get to absolute zero.

There's no way for molecules to, like, stop moving completely, but these scientists are getting really, really close.

Like I said, like, coldest temperatures in the universe close.

close.So when we say outer space, like deep, deep space, like in the vacuum, not around any other stars or galaxies, but in the middle of nowhere, it's still not 0 Kelvin.

It's still about 2.7 Kelvin, and what's crazy is that's actually the leftover heat from the Big Bang, basically.

Um-

That is a brilliant question, Emma, and it perfectly matches a message we received from one of our explorers.

An explorer named Teddy asked us, "What is absolute zero?" To answer Teddy, we have to understand what temperature actually is, and just how far down the thermometer we can travel.

[electronic whirring] Ooh, I know.

We can use my brand-new invention.

My tracks are freezing together.

[freezer buzzing] Wait a minute, 0 degrees Celsius is super cold, and my home freezer is even colder than that.

This must be absolute zero.

We found it.