Theoretically there's no positive limit to heat if memory serves, but in practice, it would indeed be surprising Now I have a doubt https://futurism.com/science-explained-hottest-possible-temperature Most recently, scientists at the Massachusetts Institute of technology (MIT) cooled molecules to just 500 billionths of a degree above absolute zero.But what about the hottest possible temperature? Is there an absolute hot? Well, things aren’t really that simple. Stopping all movement is one thing, but how do we measure maximum movement? How do we take energy up to infinity? Theoretically, it is possible. But theory isn’t necessarily what we observe in our physical reality. As such, it seems that the highest possible known temperature is 142 nonillion kelvins (1032 K.). This is the highest temperature that we know of according to the standard model of particle physics, which is the physics that underlies and governs our universe. Beyond this, physics starts to breakdown. This is known as Planck Temperature. If you are wondering, the number looks a little like this: 142,000,000,000,000,000,000,000,000,000,000 (that’s a really big number). Ultimately, this can only come about when particles achieve what is known as thermal equilibrium. In order for it to be the hottest temperature, physicists assert that the universe would have to reach thermal equilibrium, with a temperature that is so hot, all the objects are at the same temperature. The closest that scientists think we ever came to this temperature is, unsurprisingly, just after the Big Bang. At the earliest moments of our universe, spacetime expanded so fast (a period known as the inflationary period) that particles were unable to interact, which means that there could be no exchange of heat. At this juncture, scientists assert that, for all intents and purposes, the cosmos had no temperature. No heat exchange. No temperature. But this quickly ended. Scientists assert that, just a fraction of a fraction of a fraction of a second after our universe began, spacetime started to vibrate, which caused the universe to come to about 1,000,000,000,000,000,000,000,000,000 (1027) Kelvins. ... So it's not exactly positive infinity, there's a theoretical roof beyond wich >>The cosmos had no temperature.No heat exchange. No temperature. Hm Sound like "eternity", for a very brief moment But then that's what we think we know