Starts With A Bang!

Hotter and Hotter

I told you a couple of weeks ago that at extremely cold temperatures, ice entered different phases than just standard, crystalline ice that forms at the temperatures we’re used to. But what happens when we turn up the heat? Melting, sure. Boiling, yes, we all know about that. But what happens if we continue to turn up the heat? Let’s start at the bottom and work our way up:

Below 120 Kelvin: ice is just amorphous, like the structure above. Water molecules freeze and have so little energy that they can’t even move around and form into any sort of crystalline structure. But if we turn up the heat a little bit,

between 120 and 160 Kelvin: ice begins to assemble into crystals, but not the hexagonal, six-fold symmetry snowflakes we’re used to. There’s enough energy for the ice to assemble itself into some semblance of order, but not enough to make our familiar ice crystals. Instead, it makes these blocky cube-like structures shown above. It isn’t until we get above 160 Kelvin that we get the ice crystals we’re used to,

between 160 and 273 Kelvin: there’s enough energy for ice to assemble in its most energetically stable form, the form we see all around us. And this continues until we heat it up past 273.15 Kelvin, where it starts to undergo a phase transition. And then the ice melts,

between 273 and 373 Kelvin: and we have liquid water. There’s enough energy in the individual molecules that they are no longer bound to one another in a solid form; they vibrate quickly and can move far apart, and can be separated easily from one another. Still, they are somewhat bound together, if only loosely. You want to rip them farther apart? You’ll need more energy. But…

between 373 and 647 Kelvin: water becomes a gas. Individual molecules are not bound to one another, and simply diffuse away from one another. Seems pretty simple, except that we can keep turning the thermostat up! What happens if we go even higher than 647 Kelvin?

between 647 and 29,700 Kelvin: there is now no way to form a liquid phase. This is above the critical temperature for water, and no matter what you do to the pressure, no matter how high it gets, you have the same thing, a supercritical fluid/vapor. But we can keep on heating this up. And what comes next?

between 29,700 and 158,000 Kelvin: water molecules cease to exist. The temperatures are so high that hydrogen and oxygen cannot reliably stay bound to each other, and so we have different atoms just flying around, indistinguishable from water, hydrogen, or oxygen molecules. But there’s more…

between 158,000 and 81,000,000,000 Kelvin (and the caption on this was too funny to crop): electrons cannot stay bound to their nuclei, and so what was once molecules of water is now protons and oxygen nuclei flying around in a sea of electrons. The temperatures are so hot than you cannot form neutral atoms under these conditions. But we can go hotter still!

between 81,000,000,000 and 2,300,000,000,000 Kelvin: the temperature is so hot that nuclear fusion goes in reverse! All the heavy elements that have formed since the big bang get split apart into protons and neutrons, and the temperature is too hot for nuclei to re-form again. But there’s one last step we can take before our knowledge runs out:

above 2,300,000,000,000 Kelvin: it becomes too hot to have protons and neutrons. The energies are now so high that quarks and gluons are now free, and nuclei are now indistinguishable from individual quarks and gluons, in much the same way that above the critical temperature, water vapor was indistinguishable from a liquid/gas.

What happens at even higher temperatures? Maybe the LHC can shed some light…