# What's the opposite of Absolute Zero? **URL:** \ **Category:** Factual Questions\ **Created:** [February 16, 2010, 5:57am UTC](https://boards.straightdope.com/t/whats-the-opposite-of-absolute-zero/529176 "2010-02-16T05:57:01Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![YogSothoth](https://avatars.discourse-cdn.com/v4/letter/y/8edcca/32.png) [@YogSothoth](https://boards.straightdope.com/u/YogSothoth)\ **Post date:** [February 16, 2010, 5:57am UTC](https://boards.straightdope.com/t/whats-the-opposite-of-absolute-zero/529176/1 "2010-02-16T05:57:01Z")
I’m no physicist, but I know that Absolute Zero is the theoretic lower limit of temperature, where matter is at a standstill. However, given that the speed limit of matter is light speed, then shouldn’t there be a limit to how hot something can get? This [article](http://news.yahoo.com/s/nm/20100215/sc_nm/us_physics_temperature) says they created 4 trillion degrees in a lab. That must be pretty close to the limit, right? Can they calculate the limit for high temp as they do with low temp? And why is high temp so disproportionately far away from 0 than low temp? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [February 16, 2010, 6:20am UTC](https://boards.straightdope.com/t/whats-the-opposite-of-absolute-zero/529176/2 "2010-02-16T06:20:02Z")
As the particles of a gas approach the speed of light, the energy per particle, and hence the temperature of the gas, approach infinity. There is no known upper limit, in currently-known physics, for temperature. Once you get into quantum gravity, it’s plausible that there might be an upper limit to temperature, presumably somewhere in the vicinity of the Planck temperature, 10[sup]32[/sup] K. But since nobody knows how quantum gravity works, that’s just a guess. ---
**Author:** ![Oslo\_Ostragoth](https://avatars.discourse-cdn.com/v4/letter/o/a9a28c/32.png) [@Oslo\_Ostragoth](https://boards.straightdope.com/u/Oslo_Ostragoth)\ **Post date:** [February 16, 2010, 6:42am UTC](https://boards.straightdope.com/t/whats-the-opposite-of-absolute-zero/529176/3 "2010-02-16T06:42:58Z")
Consider my mind scrambled like an egg. ---
**Author:** ![Arnold\_Winkelried](https://avatars.discourse-cdn.com/v4/letter/a/3d9bf3/32.png) [@Arnold\_Winkelried](https://boards.straightdope.com/u/Arnold_Winkelried)\ **Post date:** [February 16, 2010, 7:30am UTC](https://boards.straightdope.com/t/whats-the-opposite-of-absolute-zero/529176/4 "2010-02-16T07:30:47Z")
From a certain Cecil Adams: [What is the opposite of absolute zero?](http://www.straightdope.com/columns/read/807/what-is-the-opposite-of-absolute-zero) (January 1, 1990) > [@](#): > > The highest possible temperature, called the Planck temperature, is equal to 10^32 degrees Kelvin. … The faster molecules move, the hotter they get. At 10^10 K electrons approach the speed of light, but they also become more massive, so their temperature can continue to rise. At 10^32 K such staggering densities obtain that greater temperature would cause each particle of matter to become its own black hole, and the usual understanding of space and time would collapse. Ergo, the Planck temperature is as hot as things can get. Or at least it’s the highest temp conceivable in present theory. ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [February 16, 2010, 3:08pm UTC](https://boards.straightdope.com/t/whats-the-opposite-of-absolute-zero/529176/5 "2010-02-16T15:08:19Z")
Pretty mindboggling… and yet all easily attainable with only a cheap two-slot toaster and a strawberry Pop-Tart. ---
**Author:** ![Sunspace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sunspace/32/1250_2.png) [@Sunspace](https://boards.straightdope.com/u/Sunspace)\ **Post date:** [February 16, 2010, 3:09pm UTC](https://boards.straightdope.com/t/whats-the-opposite-of-absolute-zero/529176/6 "2010-02-16T15:09:52Z")
> [@Colophon](#): > > Pretty mindboggling… and yet all easily attainable with only a cheap two-slot toaster and a strawberry Pop-Tart. Oh sure… if you’re Dr. Cockroach, that is. Us mortals have to stagger along with Easy-Bake ovens. ---
**Author:** ![Try2B\_Comprehensive](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/try2b_comprehensive/32/65_2.png) [@Try2B\_Comprehensive](https://boards.straightdope.com/u/Try2B_Comprehensive)\ **Post date:** [February 17, 2010, 3:22pm UTC](https://boards.straightdope.com/t/whats-the-opposite-of-absolute-zero/529176/7 "2010-02-17T15:22:40Z")
> [@](#): > > The highest possible temperature, called the Planck temperature, is equal to 10^32 degrees Kelvin. … The faster molecules move, the hotter they get. At 10^10 K electrons approach the speed of light, but they also become more massive, so their temperature can continue to rise. At 10^32 K such staggering densities obtain that greater temperature would cause each particle of matter to become its own black hole, and the usual understanding of space and time would collapse. Ergo, the Planck temperature is as hot as things can get. Or at least it’s the highest temp conceivable in present theory. Wow, I never made the connections of how heating things up could create a black hole! I guess I would point out that the Planck temperature is simply the end of our theory and not necessarily the upper limit i.e. maybe we could create hotter and hotter black holes. Who knows? It isn’t defined the way absolute zero is. ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [February 17, 2010, 4:26pm UTC](https://boards.straightdope.com/t/whats-the-opposite-of-absolute-zero/529176/8 "2010-02-17T16:26:46Z")
Relative infinity? 🙂 ---
**Author:** ![pravnik](https://avatars.discourse-cdn.com/v4/letter/p/8edcca/32.png) [@pravnik](https://boards.straightdope.com/u/pravnik)\ **Post date:** [February 17, 2010, 4:31pm UTC](https://boards.straightdope.com/t/whats-the-opposite-of-absolute-zero/529176/9 "2010-02-17T16:31:58Z")
> [@njtt](#): > > Relative infinity? 🙂 I typed the _exact_ same joke and decided against posting it. 😃 ---
**Author:** ![Pleonast](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pleonast/32/1183_2.png) [@Pleonast](https://boards.straightdope.com/u/Pleonast)\ **Post date:** [February 17, 2010, 5:57pm UTC](https://boards.straightdope.com/t/whats-the-opposite-of-absolute-zero/529176/10 "2010-02-17T17:57:06Z")
There are some systems that have a maximum temperature. Temperature is defined in terms of entropy. If a system has a state with maximum entropy, it also has a maximum temperature. This will be hard to grok, but the maximum temperature is enumerated 0K (absolute zero). Just as one can cool a system to arbitrarily close to absolute zero, but never reach it, one can heat a system to arbitrarily close to absolute zero, but never reach it. That is, in certain systems, we can heat it -10K, add more heat, raising the temperature to -1K, then add more to get to -0.1K, etc, but will never be able to add enough heat to reach 0K. And despite the enumeration as a negative number, it is hot, not cold. Read more about it in the [negative temperature article in the Wikipedia](http://en.wikipedia.org/wiki/Negative_temperature). ---
**Author:** ![Rumor\_Watkins](https://avatars.discourse-cdn.com/v4/letter/r/d9b06d/32.png) [@Rumor\_Watkins](https://boards.straightdope.com/u/Rumor_Watkins)\ **Post date:** [February 17, 2010, 6:05pm UTC](https://boards.straightdope.com/t/whats-the-opposite-of-absolute-zero/529176/11 "2010-02-17T18:05:04Z")
Is “freakin hot” a valid answer? ---
**Author:** ![TruCelt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/trucelt/32/523_2.png) [@TruCelt](https://boards.straightdope.com/u/TruCelt)\ **Post date:** [February 17, 2010, 7:46pm UTC](https://boards.straightdope.com/t/whats-the-opposite-of-absolute-zero/529176/12 "2010-02-17T19:46:07Z")
> [@Colophon](#): > > Pretty mindboggling… and yet all easily attainable with only a cheap two-slot toaster and a strawberry Pop-Tart. Made me snort - and that doesn’t happen often! LOL! If absolute zero = the complete lack of movement in the atoms, then wouldn’t the opposite be fission? ---
**Author:** ![Washoe](https://avatars.discourse-cdn.com/v4/letter/w/ecae2f/32.png) [@Washoe](https://boards.straightdope.com/u/Washoe)\ **Post date:** [February 17, 2010, 8:25pm UTC](https://boards.straightdope.com/t/whats-the-opposite-of-absolute-zero/529176/13 "2010-02-17T20:25:03Z")
> [@Cecil](#): > > At 10^32 K such staggering densities obtain that greater temperature would cause each particle of matter to become its own black hole, and the usual understanding of space and time would collapse. This suggests that there must also be an upper speed limit (less than _c_) to which an object can be accelerated. Go fast enough, and you collapse under the weight of your own acquired mass. Or maybe this is what happens at _c_? Is this the basis of all the fuss surrounding the LHC? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [February 17, 2010, 10:15pm UTC](https://boards.straightdope.com/t/whats-the-opposite-of-absolute-zero/529176/14 "2010-02-17T22:15:00Z")
That’s only an issue if you have multiple particles traveling in different directions. A single particle in otherwise empty space will never turn into a black hole. ---
**Author:** ![Washoe](https://avatars.discourse-cdn.com/v4/letter/w/ecae2f/32.png) [@Washoe](https://boards.straightdope.com/u/Washoe)\ **Post date:** [February 17, 2010, 10:39pm UTC](https://boards.straightdope.com/t/whats-the-opposite-of-absolute-zero/529176/15 "2010-02-17T22:39:33Z")
Do you have time right now to expound on this, or can you at least point me to an explanation? I truly have absolutely no idea what you’re talking about, but I really want to understand this. 😕 ---
**Author:** ![Critical1](https://avatars.discourse-cdn.com/v4/letter/c/3e96dc/32.png) [@Critical1](https://boards.straightdope.com/u/Critical1)\ **Post date:** [February 17, 2010, 10:59pm UTC](https://boards.straightdope.com/t/whats-the-opposite-of-absolute-zero/529176/16 "2010-02-17T22:59:08Z")
> [@YogSosoth](#): > > I’m no physicist, but I know that Absolute Zero is the theoretic lower limit of temperature, where matter is at a standstill. > [@TruCelt](#): > > If absolute zero = the complete lack of movement in the atoms, then wouldn’t the opposite be fission? while you guys are on track here, absolute zero is NOT the stopping of everything at the atomic level, that would violate the uncertainty principle. it is the lowest Possible energy state that the atoms can reach. a slight but critical difference. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [February 18, 2010, 4:11am UTC](https://boards.straightdope.com/t/whats-the-opposite-of-absolute-zero/529176/17 "2010-02-18T04:11:38Z")
The key is that it’s mass that determines whether something collapses into a black hole, and despite what you may have heard, mass does not change when you move at relativistic speed. Think of it this way: The central principle of relativity is that all reference frames are equally valid, right? Well, think about putting yourself in the reference frame of the fast-moving particle. In that frame, it’s not moving at all, so obviously its motion isn’t going to turn it into a black hole. And if you see that it’s not a black hole, so does everyone in every other reference frame, since whether something is a black hole is not the sort of thing two different observers can disagree about. ---
**Author:** ![Zorlon](https://avatars.discourse-cdn.com/v4/letter/z/d6d6ee/32.png) [@Zorlon](https://boards.straightdope.com/u/Zorlon)\ **Post date:** [February 18, 2010, 4:32am UTC](https://boards.straightdope.com/t/whats-the-opposite-of-absolute-zero/529176/18 "2010-02-18T04:32:49Z")
Imagine all the energy in creation concentrated into one tiny point. Imagine how hot that would be. That would be the hottest attainable temperature, but not the hottest possible… if there existed one iota more energy it too could be thrown on the pile. Absolute zero is the lowest temperature because it is the absence of all heat. Just like zero inches is the absence of all length. It doesn’t get any shorter. However, something could always be longer if you had a way to make it so. So too, something could always be hotter, as long as you had a way to make it hotter. ---
**Author:** ![Mosier](https://avatars.discourse-cdn.com/v4/letter/m/7ea924/32.png) [@Mosier](https://boards.straightdope.com/u/Mosier)\ **Post date:** [February 18, 2010, 7:29am UTC](https://boards.straightdope.com/t/whats-the-opposite-of-absolute-zero/529176/19 "2010-02-18T07:29:26Z")
> [@Chronos](#): > > The key is that it’s mass that determines whether something collapses into a black hole, and despite what you may have heard, mass does not change when you move at relativistic speed. > > Think of it this way: The central principle of relativity is that all reference frames are equally valid, right? Well, think about putting yourself in the reference frame of the fast-moving particle. In that frame, it’s not moving at all, so obviously its motion isn’t going to turn it into a black hole. And if you see that it’s not a black hole, so does everyone in every other reference frame, since whether something is a black hole is not the sort of thing two different observers can disagree about. So Cecil was wrong? ---
**Author:** ![StrangeBird](https://avatars.discourse-cdn.com/v4/letter/s/e480ec/32.png) [@StrangeBird](https://boards.straightdope.com/u/StrangeBird)\ **Post date:** [February 18, 2010, 7:33am UTC](https://boards.straightdope.com/t/whats-the-opposite-of-absolute-zero/529176/20 "2010-02-18T07:33:46Z")
> [@YogSosoth](#): > > And why is high temp so disproportionately far away from 0 than low temp? Zero is in different places depending on your units of measurement. It doesn’t have any intrinsic meaning for Celsius and Fahrenheit and was chosen for convenience (freezing points of water and brine respectively). For Kelvin zero is absolute zero (and the scale was constructed to make this the case). So in a sense there’s no reason commonly used zeros are relatively close to absolute zero - but no reason they should not be either. [Next page](https://boards.straightdope.com/t/whats-the-opposite-of-absolute-zero/529176.md?page=2)