system
Given the following post, respond as if you're commenting on Reddit:
human
A 2-prong question: what was the highest temperature achieved in a lab? Is there a universal limit on how high temperature can go? (we all learned about 0 Kelvin as being lowest possible, but I never heard about the highest)

What happens to matter at the highest temperature extremes? (if possible, please keep in mind that I love science however my science education level is "amateur" at best).  Thank You!
gpt
In some theories, such as string theory, there is a maximum temperature possible called the Hagedorn temperature. As the system approaches this temperature, heat put into the system excites more states more than it increases the temperature.