From the January 2014 issue

What’s the hottest possible temperature in the universe?

By | Published: January 27, 2014 | Last updated on May 18, 2023
ALICE at the Large Hadron Collider
Scientists studied data of the material produced after two streams of lead nuclei collided at the center of A Large Ion Collider Experiment (ALICE) at the Large Hadron Collider.
CERN/Maximilien Brice

Q: Does temperature have an upper limit like the lower limit of absolute zero? What’s the highest measured value?

Jane Haldiman
Chicago, Illinois 

A: The universe’s “absolute high” temperature correlates to the energy and heat that existed during the Big Bang. The physics rule that energy must be conserved doesn’t allow any more energy than that which existed at the universe’s beginning. The highest temperature that scientists have created — and thus measured — is 2 trillion kelvins. That was in the “quark-gluon plasma” created in an experiment at the Large Hadron Collider in Europe. Two streams of lead nuclei traveled toward each other at nearly light-speed. When they collided, they produced a hot plasma — the fourth state of matter made of ionized gas.

Liz Kruesi
Associate Editor