# Infinite Kelvin **URL:** \ **Category:** Factual Questions\ **Created:** [October 22, 2003, 4:54pm UTC](https://boards.straightdope.com/t/infinite-kelvin/208934 "2003-10-22T16:54:12Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![myles](https://avatars.discourse-cdn.com/v4/letter/m/779978/32.png) [@myles](https://boards.straightdope.com/u/myles)\ **Post date:** [October 22, 2003, 4:54pm UTC](https://boards.straightdope.com/t/infinite-kelvin/208934/1 "2003-10-22T16:54:12Z")
The question I saw earlier today on this board about the temperature inside a black hole, with the link to the theory of negative kelvin, sparked a question in my mind… What is the highest theoretically possible temperature? If Kelvins is a measurement of kinetic energy, wouldn’t the highest kelvin state be one in which all particles (would they have to be photons?) in said state were moving at light speed? Is this possible? What would the degrees kelvin of this state be? Or is the highest theoretically possible measurement on the kelvin scale, a state in which all particles were tachyons and moving at faster than light speed? What’s the scoop? ---
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [October 22, 2003, 5:03pm UTC](https://boards.straightdope.com/t/infinite-kelvin/208934/2 "2003-10-22T17:03:47Z")
You did read the comments in that thread along the lines of “Temperature isn’t entirely related to the motion of particles”, right? You did read the link and found out that the negative temperatures are hotter than the positive temperatures for the system in question, right? ---
**Author:** ![myles](https://avatars.discourse-cdn.com/v4/letter/m/779978/32.png) [@myles](https://boards.straightdope.com/u/myles)\ **Post date:** [October 22, 2003, 5:07pm UTC](https://boards.straightdope.com/t/infinite-kelvin/208934/3 "2003-10-22T17:07:55Z")
OK, Yes, but… the question remains, what is the theoretically highest measurement of Kelvin that is possible according to our current understanding of physics? The article spoke of infinite kelvin and negative infinite kelvin, but is such an idea applicable to the observable universe? What would the attributes of infinite kelvin be? ---
**Author:** ![Enola\_Straight](https://avatars.discourse-cdn.com/v4/letter/e/dec6dc/32.png) [@Enola\_Straight](https://boards.straightdope.com/u/Enola_Straight)\ **Post date:** [October 22, 2003, 5:14pm UTC](https://boards.straightdope.com/t/infinite-kelvin/208934/4 "2003-10-22T17:14:40Z")
Unca Cece has an article about this…the two extremes are Absolute Zero (particle motion stops absolutely) and the Planck Temperature (particles kicked up to such high energies that each particle essentialy collapses into a micro black hole). ---
**Author:** ![Jake4](https://avatars.discourse-cdn.com/v4/letter/j/bc8723/32.png) [@Jake4](https://boards.straightdope.com/u/Jake4)\ **Post date:** [October 22, 2003, 5:20pm UTC](https://boards.straightdope.com/t/infinite-kelvin/208934/5 "2003-10-22T17:20:23Z")
Temperature is average kinetic energy. KE = .5mv^2. Get something that has almost infinity mass and accelerate it to almost the speed of light, and you’ll have something that has a temperature of almost “infinity kelvin”. Doesn’t seem to make a whole lot of sense. Attributes would include being really frickin’ hot. 🙂 That’s just my simpleness talking. Check [this link.](http://www.maxwellian.demon.co.uk/art/esa/negkelvin/negkelvin.html) ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [October 22, 2003, 5:21pm UTC](https://boards.straightdope.com/t/infinite-kelvin/208934/6 "2003-10-22T17:21:26Z")
Isaac Asimov looked at this question in his science essay, “The Height of Up,” collected in _View from a Height_ and also in _Asimov on Physics_. His concluding paragraph: > [@](#): > > However, when we are working near the velocity of light or even at it as I was trying to do in Equation 8, “m” becomes very large and reaches toward the infinite regardless of the particle being considered, and so consequently does “T[sub]max[/sub]”. There is no maximum possible temperature in the Einsteinian universe any more than in the Newtonian. In this particular case, there is no definite height to up. ---
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [October 22, 2003, 5:22pm UTC](https://boards.straightdope.com/t/infinite-kelvin/208934/7 "2003-10-22T17:22:16Z")
Since infinite Kelvins can only occur in bizarre quantum situations, I don’t think there’s an answer for the question “What would it be like?” that a layperson would find intelligible. ---
**Author:** ![myles](https://avatars.discourse-cdn.com/v4/letter/m/779978/32.png) [@myles](https://boards.straightdope.com/u/myles)\ **Post date:** [October 22, 2003, 5:28pm UTC](https://boards.straightdope.com/t/infinite-kelvin/208934/8 "2003-10-22T17:28:33Z")
Thanks Enola! I’ll look it up, hmm, 10^32 Kelvin is the Planck temperature. How does this jibe with the idea of temperature as a measurement of entropy, and the possibility of positive and negative infinite temperature (as mentioned before on the page about negative K)? Can these two concepts, theoretical constructs, coexist? If 10^32 K is possible and Infinity K is possible, why nothing in-between? Does Planck temperature use an entropy-definition of temperature? If you tried to translate it to such a system, would there be any substantial differences? Please Understand, I am a history student, who enjoys philosophizing about the universe, not someone who has any idea, really, what he is talking about when it comes to stuff like this. ---
**Author:** ![MC\_Master\_of\_Ceremonies](https://avatars.discourse-cdn.com/v4/letter/m/bb73d2/32.png) [@MC\_Master\_of\_Ceremonies](https://boards.straightdope.com/u/MC_Master_of_Ceremonies)\ **Post date:** [October 22, 2003, 5:40pm UTC](https://boards.straightdope.com/t/infinite-kelvin/208934/9 "2003-10-22T17:40:29Z")
The idea that the Planck temp. is the highest temp. is completely unproven and doesn’t even have a solid theory yet to back it up, it’s just speculation on what the results of a fully-working theory of quantum gravity may be.