Thanks Abgemacht!

No problem. If you understand, please feel free to explain it : )

As said in the middle of the third column it is partially a matter of definition, which was not designed with the special case in mind, that is considered here. They say that negative temperature states are hotter and that heat would flow from a negative to a positive temperature system. That sounds reassuring!

200+ years to find out that something can be a billionth of a degree colder than absolute zero.

@Pep

Yeah after reading it, it does seem like this is mostly a matter of definition to better account for QM.

nice hot off the press too ;) so...the 'real' 'absolute for now, is now a 'fluctuation' lower? (just started reading it now...)

No, Dharmaton, that is not how I see it. The energy level distribution for a negative temperature state is fundamentally different fom the absolute zero temperature state, in that higher energy levels are more occupied or excited than lower levels.

still, it is incredible... this might be useful in orbit manufacturing

uh, does the entropy produce radiate like heat, or seep more like water? not sure I get that part correctly...

Don't take this the wrong way, but why does this matter...? It's actually a serious question...

it reminds me of a concept, let's say, included in a sci-fi novel ;-))

@bo sox, this matters because understanding the universe can allow us to manipulate it.

We can now manipulate matter into this state; which can be described as 'negative temperature' it is fundamentally different from all prevuously explored states of matter; and thus may be seen as one of the greatest break throughs of the decade, of course it may turn out to be seen as an odd curiosity for a hundred years or even forgotten (though google now allows a much easier recall of little things like this, so perhaps it will not he lost for long, or at all...)

Why does this matter? Well we don't even understand it well enough yet to say, and that matters a great deal; it is precisely where all the coolest new discoveries come from - imagine electricity 200 years ago, and you asking why does understanding how electrons move matters...

@ora

bo doesn't give two shits about any of that. Like any good high-schooler, he only cares about getting high and figuring out why he keeps striking out with girls.

Gee abge, believe it or not, I appreciate that explanation. Sometimes I wonder who else on this forum is a high schooler.

I don't know how you got your mod title if your time on these forums revolves around bashing people that would like to know something about these things. I hope whoever chooses will have better judgment next time.

Alright, let me see if I understand this:

Temperature is defined as: 1/T = del(S)/del(E).

Normally, one would expect Entropy to increase as Energy increases, thus positive Temperatures. However, as described in the paper, if you are apple to assemble a system in which High Energy States are more filled than Low Energy States, increasing Energy will decrease Entropy, causing negative Temperature.

While certainly interesting, this doesn't actually contradict any laws of Thermodynamics, specifically:

"The entropy of a perfect crystal at absolute zero is exactly equal to zero" is still true, and:

"It is impossible by any procedure, no matter how idealized, to reduce the temperature of any system to zero temperature in a finite number of finite operations" is still true.

Do I have this right?

@bo

Hey, I'm not the one going around asking questions only to mock those who answer them. Don't blame me if it bites you in the ass.

I'm not the one going around mocking those who ask questions. Don't know how I'm supposed to figure things out if I get told I'm never going to figure them out and thus shouldn't be answered.

bo

Most of the time when you ask a question, it is tongue-in-cheek. That is the reputation you've built for yourself. If you are legitimately curious about this topic, then I encourage you to participate and I'm sorry for misjudging you, although I think I can hardly be blamed given how you usually act on the forum.

If you know how I act on the forum, I don't know why you lowered yourself to my level. Takes a special kind of stupid, don't you think?

Thank you orathaic... I'm not 100% sure what it even is, but if it's comparable to the discovery of electricity, then I guess it's pretty spectacular. I'll leave you all in peace; I guess I'm not really welcome here since I don't have the guts to bash business majors anyway.

Moving right along, here are the Supplementary Materials if anyone is interested:

https://docs.google.com/file/d/0BwH0Gnsrya38OElFMmRpTkVPRGs/edit

Yes abge, all of the seems right.

It is notable that most system don't exhibit this kind of behaviour... The statistical definition of infinite temperature is one where all energy states have an equal probability of being occupied - how and ever if there is no upper limit on the possible energy then an infinite number of states exist above the zero state and it is impossible to reach an infinite temperature (without infinite energy) - so this state of negative temperature seems to have limited finite positive energy states. Which i would have thought of as a bound state - and i would also have assumed that adding enough energy would break the bond and release the particles to higher energy states... But for the purpose of this 'state of matter' (by which i'm refering to the macro-state, similar to phase) there is a point where adding energy decreases entropy.

I like the idea that this can be used to drive heat engines which have more than 100% efficiency... Because that would make it possible to do previously impossibpe things.

@Bo, sorry if ly answer didn't explain it very well. I can't imagine not wanting to know what this means... When i was 3 years old and saw my first snowfall i asked my mother (or so she reports) 'but how does god make the snow go back up?' - i think i've always been i terested in how things work, so for me figuring out the 'how' is worthwhile on it's own; what technilogy this may enable to you in the future doesn't actually matter if you just pick up your iphone 8 with selfcharging batteries and don't give a damn how it works...

Ps: i can't read the supplemental materials

Pps: how does my iphone work? It's got a touch sensitive screen, i think it uses a layer of transparent capacitors and can tell the difference between a human touch and, say a pen, because humans have a difference capacitance...

It also has accelerometers or a single axis gyroscope which tells it how it is orientated... And has all these creazy bits of software logic which i can't imagine making...

Condensed Matter is a rather busy field ;D ...to each his cup of tea lol

@ora

I'll check that link in a bit.

Yes, your iPhone has a capacitive touch screen, unlike the old resistive touch screens that you'll still encounter on things like the Nintendo DS and WiiU. Caps allow for things like multi touch.

Better also than the Theremin, with uses capacitance of the human hand; but provides no physical feedback...

Resistive touch allows pressure to change, so you can calibrate it to work with a stylus; i think i'd like a dual touch system. How and ever, i don't understand why caps allows multi touch and resistive touch would not...

I gess i am assuming that each has a series of independent sensors, which form an array... But maybe there is something else going on...

A resistive touchscreen works by creating a contact when pushing down on two panels. Based on where the contact is made, the resistance of the circuit is different. If you push down in two place, you get two resistances in parallel. The problem is that parallel resistances are equivalent to other resistances in series. It would be impossible to tell just by a resistance value if it was fine location or several that are equivalent in value to that one location.

With that being said, it can be done, but given the other advantages of capacitive touch screens, it isnt worth doing.

Also I can open it just fine. I can email it to you if you're having a problem opening it still.

Yeah, email would be great! Thx