Absolute Zero: Absolute Awesome

Sharing buttons:

Absolute Zero is the holy grail of temperatures

But even that we know exactly how cold that is

-273.15 degrees celsius

Reaching it has alluded us for centuries and will continue to allude us probably forever

For this frustration we have to thank Sir William Thomson, First Baron Kelvin

when in the mid 1800 tested a new theory that heat is just molecules moving around in a substance

So we wanted to get stuff as cold as he could get it

So he conducted experiments that drew heat from a warm substance toward a cooler one

and found that at some point all the kinetic energy could be drained from the warm substance

It could no longer be cooled any further

This temperature wasn't like melting points or boiling points which change for every substance

It was the same for everything

So Kelvin created a Thermodynamic temperature scale that measured the amount of kinetic energy within any given material

And we still use his Kelvin scale today

But ever since Kelvin's day, scientists have been trying to chill stuff to Absolute Zero and no one has succeeded

All a bunch of failures, because it turns out quantum mechanics is involved which means it´s really complicated

Physicists know that Absolute Zero does not mean a complete abscence of motion in a substance

Instead, zero degrees Kelvin marks the state of minimum motion of a substance's particles

That's because of Heinsenberg's uncertainty principle

Which says that for any ever loved particle in the universe is impossible to know both it's momentum and it's exact position at the same time

So suppose you chill a lump of lead down to the point where there's no motion going on within

Even at a subatomic level

If you could do that, you know both the particle´s positions and their momentum which would be zero

but measuring this, is, impossible, it's forbidden by the uncertainty principle

So it cannot be done

So you can't reach true Zero Kelvin but you can get pretty darn close, like a billionth of a degree away

And when you get that cold, some pretty weird stuff starts happening

Below about thirty Kelvin some substances can become superconductive

Meaning that they can carry an electrical current with no resistance

Which is super useful when you are making particle accelerators or really powerful electromagnets to put in your MRI machine

And those superconductors have been discovered that operated at much warmer temperatures

The development of the field was thanks to work at very, very cold temperatures measured on the Kelvin scale

And you might be wondering, because I was, how cold is the coldest place in the universe?

You'd think like deep space, right?

Well, yeah, space is cold, but is pretty uniformly filled with microwave radiation leftover from the Big Bang

This actually heats up space to a balmy 2.73 Kelvin

The coldest natural place in the known universe is the Boomerang Nebula which has been spitting out gas for so long that it's cool down to only about 1 Kelvin

And all of this means, that, in fact, the coldest place in the known universe

Is in laboratories right here on planet Earth, pretty cool

Thank you for watching this episode of SciShow

I hope that you got smarter

If you want to continue getting smarter, you should go to and subscribe

If you have any questions, ideas or comments leave in the comments below or get in touch with us

On Facebook or Twitter

And will see you next time