The other day, I sought to answer something that I had no idea was actually a deep scientific conundrum…
There is a temperature at which, according to our understanding of physics, nothing can get colder. As many know, we call this temperature “Absolute zero.” It’s about -460 degrees Fahrenheit, -273 degrees Celsius, or precisely 0 degrees Kelvin (by definition, the Kelvin scale is based off of absolute zero, with degree intervals equal to that of the Celsius scale).
So, my question was: is there an opposite limit for temperature?
As it turns out, quite a few people have wondered this before, and some of the brightest minds in physics have pondered it… and no conclusive answer is out there yet. There are guesses which are based on physics as we know it, but the maximum temperature, or “Absolute hot,” is an issue whose answer lies at the heart of the formation of the universe.
I don’t know the scientific background of my readers, so if I get too dumb here, I apologize.
I think the most important thing to keep in mind in this kind of physics is that matter is composed of energy and heat is a type of energy. In particular, heat is a measure of the kinetic energy (or movement) of particles in a given medium. When you “heat” something, you are increasing its internal kinetic energy so that the atoms and molecules in that substance begin moving faster and faster.
This is why heating water makes it a gas: the water undergoes a phase change at 100 degrees Celsius, which is the cutoff (boiling point) at which water is moving fast enough to evaporate into gaseous form, while the cooling of water to below 0 degree Celsius causes ice to form, which we observe as a solid substance that does not allow for the easy movement of particles. There is another phase of matter, plasma, which is achieved by heating a gas even hotter (flames are in the plasma phase, as are stars).
Oh, there is another phase that occurs near absolute zero, at which point certain matter (which exists as a gas at room temperature and a liquid at very low temperature) becomes a superfluid. I don’t know much about it, but it’s pretty damn cool to observe. Superfluids exhibit no friction or viscosity, so they act in ways you would not expect, like climbing up the walls of a glass or forming perpetual fountains which can persist indefinitely:
I know there are other phases as things get hotter, but I don’t know much about them and can’t pretend to inform you if I’m just now looking it up to see what they are. Suffice to say, I know a lot of them involve the early building blocks of the universe, as it was the cooling of the universe from extreme temperatures which caused the various forms of matter and energy to coalesce.
Based on our current assumptions about physics, there is an upper limit to how hot something can get: particles cannot move faster than light. Something cannot get hotter than the point at which its particles are moving near light speed. According to some law Einstein came up with which I don’t understand at all, the mass of an object increases at as it nears light speed. In an atom, this can occur to a point where the laws of physics as we know them no longer work in a particle.
You see, to heat something up, you keep adding energy to it so that the kinetic energy of the subatomic particles of the matter increases. As the particles near light speed, their mass increases exponentially until it would take an infinite amount of energy to accelerate the particle to the point of moving at the speed of light. At some point, the force of gravity from the increasing mass of even the most basic baryonic (or mass-possessing) matter begins to overpower that of over other competing forces. At this point, regular physics breaks down, and the atom will cease to be matter as we understand it.
That temperature, as it turns out, has a name: the Planck temperature. So, how hot is it?
Well, it’s about 1.416785×10^32 Kelvin, which is 2.550214×10^32 degrees Fahrenheit. Here, I’ll write that out for you:
141,678,500,000,000,000,000,000,000,000,000° Kelvin and Celsius (it’s basically the same, since 273 degrees difference is negligible at this temperature)
For a little bit of perspective…
Surface of our sun = 6,000° K
Center of our sun = 15,700,000° K
Neutron star about to super nova = ~100,000,000,000° K
Temperature achieved by LHC = 1,600,000,000,000° K
An interesting note: the hottest temperature ever recorded was observed during Large Hadron Collider experiments (it occurred for an infinitesimal moment in time). Take that, universe! We’re number one!
But we know the universe was once the Planck temperature, very early. In fact, it happened one Planck time after the universe began expanding. This Planck guy really liked naming stuff, huh?
As it turns out, one Planck time is so short, it’s the shortest length of time which can theoretically be measured. It’s the time it takes light to travel… wait for it… one Planck length. A Planck length is really small as well.
One Planck time is 10^-43 seconds, or…
One Planck length is 1.61619997×10^-35 meters, or…
Really fucking small. You have got to be kidding me if you want me to write out another ridiculous number that neither you nor I can ever fathom. Suffice to say, it’s so small, we have no way of currently even observing anything on that scale.
So, the universe is a tiny speck after a tiny fraction of a second into its existence as we know it… and it’s unbelievably hot. This makes sense, since there is so much energy in such a small area. I mean, you have to figure that everything in the entire universe was there in the form of pure energy, so of course it’s going to be pretty damn hot.
While this is one proposed maximum temperature, it could be lower (or higher for that matter, but I won’t bother there, because I don’t get it). String theory proposes a few possibilities, ranging from 1% of the Planck temperature (still an enormous number… just move the decimal over two places) down to just around 7% higher than temperatures achieved by the LHC. This is particularly exciting, because this means we may conceivably be able to achieve such conditions and observe the inner workings of the Big Bang.
It will be discoveries like this that help us better understand where we actually came from. If people claim that we should give thanks to the Creator, then the object of our praise should go to heat, and to the entropy that caused it to cool to the point that stars, planets, and life itself was able to take form.