What is Absolute Zero?

Hi and welcome to this video lesson on absolute zero.

Before we jump into what absolute zero is and whether or not it can be reached, let’s first discuss the idea of temperature in general.

Molecules have energy. In fact, they are always randomly moving around, and we measure that with temperature. Temperature is a gauge for how much energy those molecules have, and the more they have, the hotter we say something is. For example, if the molecules in this room were moving around very slowly, it would be very chilly in here.

Molecules have different ways of moving around, they can vibrate, the atoms rotate, and they can have a collective motion, similar to a wave of water. These all factor into the temperature of stuff.

Now, for absolute zero. There are three fairly popular measurements for gauging temperature. There’s Fahrenheit, Celsius, and Kelvin. In Kelvin, which is what most physicists like to use, 0 is absolute zero. Now, just because we can say absolute zero exists, does not mean we actually can reach or observe it. Here’s why…

To have something at absolute zero in theory means it has no kinetic energy, but that’s not possible, because then the materials would cease to exist as normal matter, due to laws of quantum mechanics.

Let me explain:
The coldest observable temperatures that have been reached are within a fraction of a degree of 0 Kelvin. At this temperature, the gases these scientists were experimenting on became interlaced in such a way that they were no longer gas, liquid, or solid, they were something else, never before seen.

So, from these and other tests, physicists believe that even if we get close to absolute zero, it is never actually attainable because the atoms of an element must always be in some type of motion. The electrons for example will always have some kinetic energy, even if it is simply a small vibration.

I hope that answers some of your questions on Absolute Zero. Thanks for watching and, until next time, happy studying

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