# What is the hottest spot in the universe? Is there an "absolute zero" in the other direction? **URL:** \ **Category:** Factual Questions\ **Created:** [August 17, 2016, 7:34pm UTC](https://boards.straightdope.com/t/what-is-the-hottest-spot-in-the-universe-is-there-an-absolute-zero-in-the-other-direction/763118 "2016-08-17T19:34:20Z")\ **Posts on this page:** 14\ **Page:** 1
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [August 17, 2016, 7:34pm UTC](https://boards.straightdope.com/t/what-is-the-hottest-spot-in-the-universe-is-there-an-absolute-zero-in-the-other-direction/763118/1 "2016-08-17T19:34:20Z")
See queries. 1st query) “Hottest” over any time scales: down to incredibly short/ “instantaneous”–although defining “an instant” may involve 2nd query) is there a temperature where matter is no longer matter? I have no idea quite what that means, in case anyone wasn’t sure. I was blabbing about absolute zero to someone who stopped me cold (heh) with that question. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [August 17, 2016, 7:38pm UTC](https://boards.straightdope.com/t/what-is-the-hottest-spot-in-the-universe-is-there-an-absolute-zero-in-the-other-direction/763118/2 "2016-08-17T19:38:01Z")
The hottest spot is probably the instant of maximum crunch during a Supernova explosion, but infalling matter impacting a Neutron star is probably really close. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [August 17, 2016, 7:38pm UTC](https://boards.straightdope.com/t/what-is-the-hottest-spot-in-the-universe-is-there-an-absolute-zero-in-the-other-direction/763118/3 "2016-08-17T19:38:27Z")
Also: prizes to first person to add “…but it’s a dry heat.” ---
**Author:** ![chacoguy](https://avatars.discourse-cdn.com/v4/letter/c/50afbb/32.png) [@chacoguy](https://boards.straightdope.com/u/chacoguy)\ **Post date:** [August 17, 2016, 7:40pm UTC](https://boards.straightdope.com/t/what-is-the-hottest-spot-in-the-universe-is-there-an-absolute-zero-in-the-other-direction/763118/4 "2016-08-17T19:40:58Z")
[CERN might be hottest.](http://www.themarysue.com/cern-hottest-manmade-temperature/) ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [August 17, 2016, 7:41pm UTC](https://boards.straightdope.com/t/what-is-the-hottest-spot-in-the-universe-is-there-an-absolute-zero-in-the-other-direction/763118/5 "2016-08-17T19:41:46Z")
> [@Leo\_Bloom](#): > > Also: prizes to first person to add “…but it’s a dry heat.” [![CloudApp](https://f.v1.n0.cdn.getcloudapp.com/items/2l1S170K2S1x003R0T3C/Screen%20Shot%202016-08-17%20at%2012.41.53%20PM.png "Screen Shot 2016-08-17 at 12.41.53 PM") ](https://cl.ly/2Nu5wqZj) ---
**Author:** ![buddha\_david](https://avatars.discourse-cdn.com/v4/letter/b/ee7513/32.png) [@buddha\_david](https://boards.straightdope.com/u/buddha_david)\ **Post date:** [August 17, 2016, 7:45pm UTC](https://boards.straightdope.com/t/what-is-the-hottest-spot-in-the-universe-is-there-an-absolute-zero-in-the-other-direction/763118/6 "2016-08-17T19:45:39Z")
[Absolute Hot,](https://en.wikipedia.org/wiki/Absolute_hot) aka the Planck Temperature, is believed to be approx. 1.416×10[sup]32[/sup] Kelvin, based on our current understanding of the Universe. The last (and presumably only) time anything was that hot was at the very start of the Big Bang. CERN’s record temperature of 7.2 trillion degrees is far, far hotter than any natural process happening right now in the Universe, except for alien planets of course. ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [August 17, 2016, 7:45pm UTC](https://boards.straightdope.com/t/what-is-the-hottest-spot-in-the-universe-is-there-an-absolute-zero-in-the-other-direction/763118/7 "2016-08-17T19:45:46Z")
There is an absolute zero. You can determine where it is theoretically from the ideal gas law. More info on the wikipedia page here: > **[Absolute zero](https://en.wikipedia.org/wiki/Absolute_zero)** > > Absolute zero is the lowest limit of the thermodynamic temperature scale; a state at which the enthalpy and entropy of a cooled ideal gas reach their minimum value. The fundamental particles of nature have minimum vibrational motion, retaining only quantum mechanical, zero-point energy-induced particle motion. The theoretical temperature is determined by extrapolating the ideal gas law; by international agreement, absolute zero is taken as 0 kelvin (International System of Units), which is −273... The Kelvin temperature scale uses absolute zero as its zero point. The universe on average is pretty cold, about 2.73 deg Kelvin (according to the google) or about -270 deg C. It’s not zero since there is some residual energy left over from the Big Bang. NASA is going to try to create the coldest spot in the known universe inside the ISS: The Coldest Spot in the Known Universe: [http://science.nasa.gov/science-news/science-at-nasa/2014/30jan\_coldspot/](http://science.nasa.gov/science-news/science-at-nasa/2014/30jan_coldspot/) This dates from 2009, so I don’t know if there’s any newer info. Hottest spot in the universe found [http://www.skymania.com/wp/2009/11/hottest-spot-in-universe-found.html/753/](http://www.skymania.com/wp/2009/11/hottest-spot-in-universe-found.html/753/) > [@](#): > > Space scientists have discovered the hottest place known in the universe where temperatures reach an amazing 300 million degrees C. > > A cloud of searing gas is surrounding a swarm of galaxies clustered together five billion light-years away in the constellation of Virgo. ---
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [August 17, 2016, 7:53pm UTC](https://boards.straightdope.com/t/what-is-the-hottest-spot-in-the-universe-is-there-an-absolute-zero-in-the-other-direction/763118/8 "2016-08-17T19:53:06Z")
> [@Leo\_Bloom](#): > > See queries. > > 1st query) “Hottest” over any time scales: down to incredibly short/ “instantaneous”–although defining “an instant” may involve > > 2nd query) is there a temperature where matter is no longer matter? I have no idea quite what that means, in case anyone wasn’t sure. I was blabbing about absolute zero to someone who stopped me cold (heh) with that question. Back before we could say “There’s an XKCD for this,” we could say “There’s an Asimov essay on this” - and there are two in fact “The Height of Up” and “Hot Stuff” [http://www.asimovreviews.net/Books/Book053.html](http://www.asimovreviews.net/Books/Book053.html) (see also [Isaac Asimov, Data Journalist? – Jamie Todd Rubin](http://www.jamierubin.net/2014/05/07/isaac-asimov-data-journalist/)). Well worth checking out. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [August 17, 2016, 8:12pm UTC](https://boards.straightdope.com/t/what-is-the-hottest-spot-in-the-universe-is-there-an-absolute-zero-in-the-other-direction/763118/9 "2016-08-17T20:12:03Z")
> [@engineer\_comp\_geek](#): > > … > The Coldest Spot in the Known Universe: > [http://science.nasa.gov/science-news/science-at-nasa/2014/30jan\_coldspot/](http://science.nasa.gov/science-news/science-at-nasa/2014/30jan_coldspot/) > > This dates from 2009, so I don’t know if there’s any newer info. > Hottest spot in the universe found > [http://www.skymania.com/wp/2009/11/hottest-spot-in-universe-found.html/753/](http://www.skymania.com/wp/2009/11/hottest-spot-in-universe-found.html/753/) OP here: Do you/they know how long the oven can stay lit at this temperature? I was thinking about this when I mentioned “time scale.” Equally interesting are winners in categories, like “longest time at highest maintained temperature” (short of the the universe itself, maybe, as Tom Stoppard calls “the lukewarm tea” of the heat death). Re shortest time/time scale: FTR, and a pat on my own back, I guessed Planck scale would come into this (my segue to query 2), and quark “breakdown,” but was afraid to say so. I’m intimidated (rightly, I guess) with using big words around here when I only remotely grasp their import. ETA also thanks for the posts ---
**Author:** ![Trinopus](https://avatars.discourse-cdn.com/v4/letter/t/2bfe46/32.png) [@Trinopus](https://boards.straightdope.com/u/Trinopus)\ **Post date:** [August 17, 2016, 9:18pm UTC](https://boards.straightdope.com/t/what-is-the-hottest-spot-in-the-universe-is-there-an-absolute-zero-in-the-other-direction/763118/10 "2016-08-17T21:18:20Z")
Wouldn’t the coldest naturally occurring temperature be equal to the microwave background temperature? To get below that, you need a heat pump. Do heat pumps occur in nature? ---
**Author:** ![eburacum45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eburacum45/32/8690_2.png) [@eburacum45](https://boards.straightdope.com/u/eburacum45)\ **Post date:** [August 17, 2016, 9:37pm UTC](https://boards.straightdope.com/t/what-is-the-hottest-spot-in-the-universe-is-there-an-absolute-zero-in-the-other-direction/763118/11 "2016-08-17T21:37:00Z")
> [@Trinopus](#): > > Wouldn’t the coldest naturally occurring temperature be equal to the microwave background temperature? To get below that, you need a heat pump. Do heat pumps occur in nature? Yes. The [Boomerang Nebula](https://en.wikipedia.org/wiki/Boomerang_Nebula) consists of some rapidly expanding gas forced through a magnetic bottleneck; basically a giant aerosol can, or a natural demonstration of the Joule-Thomson effect > **[Joule–Thomson effect](https://en.wikipedia.org/wiki/Joule%E2%80%93Thomson_effect)** > > In thermodynamics, the Joule–Thomson effect (also known as the Joule–Kelvin effect or Kelvin–Joule effect) describes the temperature change of a real gas or liquid (as differentiated from an ideal gas) when it is expanding; typically caused by the pressure loss from flow through a valve or porous plug while keeping it insulated so that no heat is exchanged with the environment. This procedure is called a throttling process or Joule–Thomson process. The effect is purely an effect due At room tem... ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [August 17, 2016, 10:36pm UTC](https://boards.straightdope.com/t/what-is-the-hottest-spot-in-the-universe-is-there-an-absolute-zero-in-the-other-direction/763118/12 "2016-08-17T22:36:14Z")
This is a total cheat, but the inside of a laser (or a few other unusual systems) is the “hottest temperature”. In fact, the active part of the lasing material is at a _negative temperature_ which, even more absurdly, is hotter than any positive temperature. I don’t mean negative Celsius, of course–I mean negative Kelvin. It is hot in the sense that heat will flow from this material to any material that’s a positive temperature–even those trillion-degree CERN particles. All of this is a result of the strange way that temperature is defined: the ratio of how much internal energy increases divided by the increase in entropy. This doesn’t quite match our intuitive notion of temperature as a bunch of bouncing particles, where the temperature goes up as they bounce more quickly, but it is the most consistent physical definition of the concept. Systems such as lasers can get into a state where entropy _decreases_ as the energy increases, which gives them a negative temperature. Heat will always flow from one of these systems to one with positive temperature. As I said, it’s a cheat, but it’s physically accurate. Note that this situation can’t happen with “ordinary” hot objects such as a hot gas, since as they get hotter the number of internal states (and hence entropy) can increase without bound. It can only happen when there is a finite number of internal states that can be filled. ---
**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:** [August 17, 2016, 11:46pm UTC](https://boards.straightdope.com/t/what-is-the-hottest-spot-in-the-universe-is-there-an-absolute-zero-in-the-other-direction/763118/13 "2016-08-17T23:46:54Z")
> [@](#): > > Quoth **beowulff** : > > The hottest spot is probably the instant of maximum crunch during a Supernova explosion, but infalling matter impacting a Neutron star is probably really close. In fact, one kind of supernova is a result of matter falling onto a neutron star. CERN might be able to get higher energies per particle than supernova cores, but there aren’t really enough particles involved there for the concept of “temperature” to be meaningful. And if we insist on applying the concept of “temperature” to such small systems anyway, then there are naturally-occurring particles with much higher energies than anything CERN can accomplish, like the Oh-my-God particle (though we’re unsure just what produces such particles). For the coldest, it depends on whether we’re talking about coldest object, or coldest place. Black holes have exceedingly low temperatures (perhaps 10^-16 or 10^-17 kelvin for the largest ones), but their immediate environment is the 3K cosmic microwave background. Ordinarily, an object like that would reach thermal equilibrium with its surroundings, but black holes actually have a negative specific heat: The more energy they absorb, the colder they get. If you don’t want to count black holes, then the coldest known temperatures are all going to be in Earthly labs. Though there are probably some aliens out there somewhere who’ve gone even further than we have. ---
**Author:** ![Saint\_Cad](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/saint_cad/32/18907_2.png) [@Saint\_Cad](https://boards.straightdope.com/u/Saint_Cad)\ **Post date:** [August 19, 2016, 1:14am UTC](https://boards.straightdope.com/t/what-is-the-hottest-spot-in-the-universe-is-there-an-absolute-zero-in-the-other-direction/763118/14 "2016-08-19T01:14:39Z")
[vsauce](https://www.youtube.com/watch?v=4fuHzC9aTik) does a good job on this.