eli5: Why is it temperatures can go up to the trillions but only down to -273?

Question

eli5: Why is it temperatures can go up to the trillions but only down to -273?

In: Physics

Answer 1

Imagine you have a car. It’s a really fast car, but for some reason, the car has a speedometer that shows 0 at 100 km/h.

If you slow down 10 km/h from “0”, the speedometer says -10. Can you slow down from -100? Why not?

Temperature scales measure the movement of particles. A particle can only slow down until it stops moving, at that point it can’t go any slower. Like our car that stops moving at -100, particles stop moving at -273 C. Now, if you want a “speedometer” that puts 0 at 0, then instead of Celsius you’d use Kelvin.