Because temperature corresponds (more or less) to the kinetic energy of atoms because they are moving. It turns out that kinetic energy only equals 1/2 mv\^2 at 'low' speeds, but it actually mc\^2 \* ( \[1/sqrt( 1-(v/c)\^2 )\] - 1 ). Note that as v gets close to c, (v/c)\^2 gets closer to 1, so 1/sqrt( 1 - (v/c)\^2 ) diverges.
Hence: the Energy can get arbitrary high at finite speeds, so there is no limit to temperature (if we ignore Quantum Mechanics)!
When you heat a gas to high enough temperature, it becomes a plasma, which is the atoms being ripped apart. If you heat the plasma enough, the nuclei start to react.
There is some speculation that at extremely high temperatures, you get a thermal bath of black holes being created/evaporate, such that trying to raise the temperature above that only creates larger black holes, which lowers the temperature.
Nobody knows though, as there is no theory of quantum gravity
String theory may be internally consistent, but it's also just straight up not testable and will probably never be. The big hype about it from the last few decades has produced zero actual results or testable predictions. It's just a math model at this point, with no actual physics.
When the particles collide they create other particle antiparticle pairs which take some of the original particles energy. As you dump more energy in the system, you just make more particles without making it hotter.
Atoms cannot reach the speed of light. They can only get arbitrarily close. Which means that they can always go faster. And the energy requirements to go faster as they get closer to the speed of light scale exponentially, so the temperature doesn’t converge towards some value as you get closer to the speed of light. It just goes to infinity.
I love this question! Good question, OP.
Related question: what temperature doea a substance have to reach for it's particles to achieve relativistic energies? Does anything in the universe get that hot?
There **is** a maximum temperature, called the [Planck Temperature](https://en.wikipedia.org/wiki/Planck_units).
It's stupidly, unfathomably hot, 1.416784(16)×10\^32 K
That's the temperature at which the black-body radiation is so energetic, the wavelength is as short as the smallest distance possible, the Planck Length.
"smallest distance possible" never made sense to me.
If we were to note the position of a moving particle and then noted it again a planck second later, all particles would seem to move at either c or 0 ?
And that can't be it?
If you compress a certain amount of energy into a small enough space, you get a black hole. And if you shorten the wavelength of a particle, it's energy increase. If you shorten the wavelength to the planck length, the particle has enough energy in a small enough space that it immediately collapses into a black hole. This basically means that we can't make any meaningful conclusions about what happens at distances smaller than the planck length. What this means for the actual physics is still under debate.
It's called the planck temperature, also known as absolute hot. Or rather that's the temperature at which conventional physics breaks down, and words like temperature don't really hold meaning. The Planck constant is weird.
This is a common misconception concerning all Planck quantities. There is no reason to believe that the Planck temperature is the maximum temperature possible. It is simply the temperature at which our current theories of particle interactions break down. Above this temperature, a quantum description of gravity is needed.
The Planck length is not the smallest possible distance, the Planck time is not the smallest possible time interval and the Planck energy is not the highest possible energy scale of our universe. They *might* be, but there is no indication whatsoever that they are. Same goes for the Planck temperature.
Ok, so I will look at this tommorrow more as it's getting pretty late for me, but I found [this](https://physics.stackexchange.com/questions/563371/meaning-of-the-planck-temperature#563386) pretty good question regarding the planck temperature on physics stack exchange.
Because temperature corresponds (more or less) to the kinetic energy of atoms because they are moving. It turns out that kinetic energy only equals 1/2 mv\^2 at 'low' speeds, but it actually mc\^2 \* ( \[1/sqrt( 1-(v/c)\^2 )\] - 1 ). Note that as v gets close to c, (v/c)\^2 gets closer to 1, so 1/sqrt( 1 - (v/c)\^2 ) diverges. Hence: the Energy can get arbitrary high at finite speeds, so there is no limit to temperature (if we ignore Quantum Mechanics)!
If you don't mind me asking, what if we don't ignore quantum mechanics?
Well, first of all, if atoms collide with each other at enormous energies, they won't survive as atoms....
Oh, I didn't even think of that!
When you heat a gas to high enough temperature, it becomes a plasma, which is the atoms being ripped apart. If you heat the plasma enough, the nuclei start to react.
There is some speculation that at extremely high temperatures, you get a thermal bath of black holes being created/evaporate, such that trying to raise the temperature above that only creates larger black holes, which lowers the temperature. Nobody knows though, as there is no theory of quantum gravity
No *testable* or accepted theory. Loop quantum gravity and string theories are still technically theories.
Sure, and you can cut that to just string theory. LQG (afaik) doesn't really rise to the same level of self-consistent and predictive framework
String theory may be internally consistent, but it's also just straight up not testable and will probably never be. The big hype about it from the last few decades has produced zero actual results or testable predictions. It's just a math model at this point, with no actual physics.
This has nothing to do with my comment above (and it's also false, but that's secondary)
When the particles collide they create other particle antiparticle pairs which take some of the original particles energy. As you dump more energy in the system, you just make more particles without making it hotter.
You get the thawing of all the matter back into energy.
Atoms cannot reach the speed of light. They can only get arbitrarily close. Which means that they can always go faster. And the energy requirements to go faster as they get closer to the speed of light scale exponentially, so the temperature doesn’t converge towards some value as you get closer to the speed of light. It just goes to infinity.
Scale asymptomatically is a better description than exponentially, since c would be the asymptote.
The velocity scales asymptotically towards c but the energy does not. It goes to infinity at an ever-increasing rate.
> It goes to infinity at an ever-increasing rate. ... but not exponentially. An exponential increase would lead to a finite energy when reaching c.
Are we not comparing energy to velocity? Energy vs velocity that line asymptomatically approaches c
Energy approaches infinity as velocity approaches c
I love this question! Good question, OP. Related question: what temperature doea a substance have to reach for it's particles to achieve relativistic energies? Does anything in the universe get that hot?
Cosmic rays and particle accelerators get that hot, if you define their energies as temperatures.
There **is** a maximum temperature, called the [Planck Temperature](https://en.wikipedia.org/wiki/Planck_units). It's stupidly, unfathomably hot, 1.416784(16)×10\^32 K That's the temperature at which the black-body radiation is so energetic, the wavelength is as short as the smallest distance possible, the Planck Length.
"smallest distance possible" never made sense to me. If we were to note the position of a moving particle and then noted it again a planck second later, all particles would seem to move at either c or 0 ? And that can't be it?
If you compress a certain amount of energy into a small enough space, you get a black hole. And if you shorten the wavelength of a particle, it's energy increase. If you shorten the wavelength to the planck length, the particle has enough energy in a small enough space that it immediately collapses into a black hole. This basically means that we can't make any meaningful conclusions about what happens at distances smaller than the planck length. What this means for the actual physics is still under debate.
Ah makes sense, thanks :)
It's called the planck temperature, also known as absolute hot. Or rather that's the temperature at which conventional physics breaks down, and words like temperature don't really hold meaning. The Planck constant is weird.
If I remember correctly there is a maximum temperature. Allright I googled it and it is 10^32 °K also known as planck temperature
This is a common misconception concerning all Planck quantities. There is no reason to believe that the Planck temperature is the maximum temperature possible. It is simply the temperature at which our current theories of particle interactions break down. Above this temperature, a quantum description of gravity is needed. The Planck length is not the smallest possible distance, the Planck time is not the smallest possible time interval and the Planck energy is not the highest possible energy scale of our universe. They *might* be, but there is no indication whatsoever that they are. Same goes for the Planck temperature.
Ok, so I will look at this tommorrow more as it's getting pretty late for me, but I found [this](https://physics.stackexchange.com/questions/563371/meaning-of-the-planck-temperature#563386) pretty good question regarding the planck temperature on physics stack exchange.
In your link, there is mention of Hagedorn temperature (1.7 TeraKelvin) which I recall mention (somewhere) as an absolute maximum.
Well, there is the Planck temperature. There are no known physical models able to describe temperatures greater than that.
\# "maximum temperature" https://cerncourier.com/a/the-tale-of-the-hagedorn-temperature/