My Little Pony XIX: I Emptied Your Thread

[erikun]

You can't get truly sub-0 K tempertaures in nature, no. You just can't get less than absolute zero, because you can't get less than zero particle movement (as it is physically impossible to have negative movement!)

* Zero absolute particle movement. It is entirely possible to have positive and negative movement, such as on a number line where positive is in one direction and negative is the opposite. In that case, negative movement would simply be in the direction of the negative "pole".

There is not a way to have less than no movement, though.

With magic or technology well beyond Earth's level, you can utilise elemental cold; which is the opposite of heat, rather than merely it's absence, as "cold" is naturally in the material universe; and this has it's own set of laws and behaviors. (I'm a necromancer, not a physist, at the end of the day, so I'm not easily able to explain it except in broad terms!)

Heat transfers from one system to another, until both systems have reached equilibrium. That is, if you have one system at 0 K and another at 300 K (and have the same mass), then you end up with both at 150 K in the end.

I just treat an "elemental cold" as one system remaining at 0 K, absorbing heat but not changing temperature. Thus, the second system will drop to 150 K, then 75 K, and continue dropping in temperature as long as the elemental cold remains. In that case, you end up with situation resembling radioactive half-lifes, where the "coldness" or the volume doesn't matter as much as how quickly heat can be transferred out of the material object.

It also produces some fun situations with extremely hot objects. (You will reduce the object to half its current temperature in the same amount of time, regardless of the currect temperature, so starting very hot causes far more temperature stresses.)

from what I remember of discussions of high school chemistry, theoretically anything that falls below 0 kelvin would become anti-matter

No, anti-matter particles are just regular matter particles that have the opposite charges (negatively charged protons, positively charged electrons).

From what I understand of antimatter, it is simply matter with an opposite electrical charge. This wouldn't really make it "negative temperature" matter, both because having the same properities in the opposite direction isn't a negative temperature (see my first comment above) and that electrical charge is a binary state, not a matter of degrees.

I'm not saying that you couldn't create antimatter by dropping regular matter below 0 K, but given that we can't even reach 0 K with current technology, it is obviously purely theoretical. And just as clearly not how existing antimatter is formed.

Hi Erikun! Having fun?

Yay for being noticed!

given that I recall absolute zero being defined in celsius scale, I didn't put much stock into it. The most important thing I was taught in school was how very little they actually taught me in school. Aside from "a kilogram is 2.2 pounds", my knowledge of physics is self-taught.

0 Kelvin = -273.15 Celcius, exactly. (Centigrade is another term for Celcius.) In fact, the definition of Kelvin is to be identical to the Celcius scale (+1 K = +1 C) except that 0 K is set at absolute zero, rather than at the freezing point of water at Standard-Temperature-Pressure.

I read at one point about a study showing that under enough pressure, matter would overlap. That is, the smallest particles, which theoretically should be utterly solid, rather than having a large percentage of their structure taken up by empty space, would occupy the same space. Despite such a thing being physically impossible.

So, given that we can have matter occupy other matter (I think it was about phasing, unsure though) and space beyond space a la a hypercube, is it possible to have negative movement? Despite being unable to conceive of negative movement, that is.

Huh, this depends on what we mean by "matter would overlap". If we just mean that it would overcome the standard atomic resistances and having the matter of two atoms in the normal space of one, then that doesn't sound too revolutionary. In fact, that is exactly what happens with plasma, where the standard atomic structure falls apart and we end up with a subatomic "soup".

If we are talking about literal matter occupying the same space as matter, I'd think we were dealing with quantum trickery or exceptional bending of spacetime, as opposed to the creation of additional dimensions à la a hypercube.

I'm still not seeing how we would produce negative movement - in the sense of less than no movement, as opposed to moving it into a different direction. I suppose if we are monkeying around with dimensions, we could say that moving it backwards along the time dimension could count as negative movement...

Given that matter is energy is matter, disintegration at crazy impossibly low temperatures makes sense.
Negative temperatures seem to be a result of the universe not compiling in this specific case the way our general-case equation would say it should. Defining temperature using two other variables is a novel but understandable concept. Silly quantifiers. Some things just are

I believe I read somewhere (or perhaps just throught up) that actual absolute zero would have no energy in the system. None. This includes such things like gravity, electromagnetic, and weak nuclear force. Perhaps this is just how I take the definition to be - if there was some kind of force holding matter together, then it would provide energy for the system and thus keep it above 0 K. Needless to say, without any energy, the matter would simply fall apart. There'd be no chemical bonds to hold molecules together, no magnetism holding atoms together, no WNF holding nuclei together. Everything that makes up matter would just crumble apart.

It's kind of like matter falling apart with plasma, above, although for the opposite reason.

I can certainly understand that things which (apparently) ignore standard physics aren't going to behave as we would expect them to. I guess I'm just wondering why matter would still exist for that long to reach such a low actual negative temperature, since there isn't anything holding it together at an actual 0 K.