How hot do things get? I’ve found references to around 4e9 K for things like magnetar surfaces, the inner edge of black hole accretion disks, and the centers of the largest stars (dammit, tho, I can’t see where I put them).
I saw the limit-to-temperature reference from Cecil that talks about the Planck temperature, but I’m looking for actual objects, not theoretical limits.
Thanks!
About as hot as I am sizzle
You don’t know how hot 'till you try it…
Are you interested in the current Universe specifically? Because very early in its history, the entire Universe was up in the vicinity of that Planck temperature mentioned by Cecil. For something a little more contemporary, it’s expected that there should be some (though nobody knows how many) small black holes left over from the Big Bang, some of which are presumably reaching their final stages of evaporation right around now. An evaporating black hole would also presumably reach temperatures comparable to the Planck temperature, though only for a very short time.
Now, we’ve never actually seen a black hole evaporating, but then, to be fair, we’ve never seen a stellar core. The hottest thing we’ve ever seen is probably a magnetar surface (some accretion disks might be hotter, but the hottest ones are in quasars, which don’t exist any more). But if you really want to warp your brain, neutron stars (even at their cores) can be considered to be at zero temperature, to an excellent approximation: The effects of even such huge temperatures are negligible compared to the quantum mechanics going on in a neutron star.
Very hot.
I wonder at what point in time was the hottest temperature. I think that at the primordial stages of the universe was the hottest.
What is this “Planck temperature”? How can hotness have an upper limit?
Answers.com on Planck temperature
As near as I can establish, it’s the maximum temperature to which matter can be raised under any circumstances, because no more energy can be added to increase the temperature above it. Someone who understands extreme-level physics better than I can do a better job of explaining this, though.
In which case, you’ll be waiting a few hundred years. Nobody really understands extreme-level physics yet, nor do we expect to understand any time soon. We don’t know that temperatures hotter than the Planck temperature are impossible, but it’s very safe to say that by the time you get to such temperatures, the laws of physics behave in a manner very different than the ways in which we’re familiar. It may be that higher temperatures can exist, but it’s much more likely that above that, the term “temperature” becomes meaningless. It’s even possible that the temperature at which things go all wonky is considerably below the Planck temperature, and we just don’t know it yet.
Oh, and Cecil’s article