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4387 clicks; posted to Geek » on 04 Jan 2013 at 11:58 AM (4 years ago)   |   Favorite    |   share:    more»

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That article made my brain hurt. Where do they make the logic jump from "effectively a billionth of a degree below zero kelvin" and "engines that are more than 100% efficient"

You can never get to zero so long as you have an infinite number of decimal places on your scale.

This is why math must be stopped. Well, that and because Jesus.

As a comment suggests, lasers have had negative temperature for decades. Infinite temperature has all energy states of a system populated in proportional to some bizarre quantum statistical numbering scheme. Positive temperature has lower energy states disproportionately occupied, negative temperature has higher states occupied.  Traditional lasers rely on an excess of electrons in high energy states.

Well that's probably with wind chill

I don't understand any of that but it seems to me that if 'absolute zero' is the term for the lowest possible temperature and someone gets below that, then shouldn't 'absolute zero' be redefined with the new value?

stratagos: That article made my brain hurt. Where do they make the logic jump from "effectively a billionth of a degree below zero kelvin" and "engines that are more than 100% efficient"

negative temperature, negative pressure;

http://en.wikipedia.org/wiki/Carnot_heat_engine

Slaxl: I don't understand any of that but it seems to me that if 'absolute zero' is the term for the lowest possible temperature and someone gets below that, then shouldn't 'absolute zero' be redefined with the new value?

No, because the new value seems to be some kind of new state beyond no atomic motion (which is absolute zero) so the negative designation makes sense.

Slaxl: I don't understand any of that but it seems to me that if 'absolute zero' is the term for the lowest possible temperature and someone gets below that, then shouldn't 'absolute zero' be redefined with the new value?

Do not think of it as below, but rather opposite.

In the article they state "objects with negative temperatures are always hotter than ones with positive temperatures.".

Yahoo was just fishin for hits with their title.

Slaxl: I don't understand any of that but it seems to me that if 'absolute zero' is the term for the lowest possible temperature and someone gets below that, then shouldn't 'absolute zero' be redefined with the new value?

Absolute zero is defined as the cessation of all molecular motion. While I'm not sure how they did this, they circumvented that scale somehow.

doglover: Slaxl: I don't understand any of that but it seems to me that if 'absolute zero' is the term for the lowest possible temperature and someone gets below that, then shouldn't 'absolute zero' be redefined with the new value?

No, because the new value seems to be some kind of new state beyond no atomic motion (which is absolute zero) so the negative designation makes sense.

It's like backwards entropy, fizzy lifting drink for the density of occupied states.

QuantuMechanic: doglover: Slaxl: I don't understand any of that but it seems to me that if 'absolute zero' is the term for the lowest possible temperature and someone gets below that, then shouldn't 'absolute zero' be redefined with the new value?

No, because the new value seems to be some kind of new state beyond no atomic motion (which is absolute zero) so the negative designation makes sense.

It's like backwards entropy, fizzy lifting drink for the density of occupied states.

Also it's not the macroscopic temperatue, but a mathematical one. A better explanation to a layperson would be "It's just math. If you want the blunt skippy, go bone up on your basic quantum physics. If you don't fall asleep in ten minutes, I'll try to answer your question."

Also it should be pointed out that they are not "cooling" i.e. reducing the entropy in all degrees of freedom; only certain ones they choose through the design of their experiment.

This type of "temperature" is very difficult to relate to how and what we experience as temperature.

Here's the wiki: Negative temperature

But "negative temperature" != "below absolute zero"

Negative temperature is not a new phenomenon, in lasers it's called "Population inversion" and it's how you get lasers to do their thing.

Think of it in terms of gravity. If you have gravity in one direction, you can call it "positive" gravity, and you're pulled towards the Earth. If you have "zero" gravity, you're not pulled anywhere, and just float. If you have "negative" gravity (anti-gravity), you are pushed away from the Earth. This doesn't mean you are feeling less force than the zero gravity situation, just that the force is pointing the other direction than you designated positive gravity.

Similarly, negative temperature is when the particles naturally settle uphill, rather than downhill, as it were.

Some body divided by absolute zero, dammit.

Regardless of the science behind the article, it is still a very appropriate use of the cool tag.

Reading that article makes me think "This is what it's like to get old. I read the article, and the words make sense, but conceptually I just can't wrap my head around it. Confounded iPod3MP player device."

so.. in negative temps... the atoms shiver and are hotter then their surroundings while still being colder?

umm.. yeah. thats exactly how I feel when naked and drunk and wet outside in the winter so how is this new>?

Isn't absolute 0 just a term for where the subatomic particles freeze? I would think that there could be a temperature colder then that.

Yeah, lasers, basically, but these guys seem to have done it in a different system with some interesting effects.

The "easiest" way I've been able to understand this is they've created a system where adding energy serves to decrease the systems entropy. So they've created a roughly macroscopic system that exhibits that property. Which is pretty "cool".

"A substance with a negative temperature is not colder than absolute zero, but rather it is hotter than infinite temperature." actually seems like it makes more sense to me...

nmrsnr: Here's the wiki: Negative temperature

But "negative temperature" != "below absolute zero"

Negative temperature is not a new phenomenon, in lasers it's called "Population inversion" and it's how you get lasers to do their thing.

Think of it in terms of gravity. If you have gravity in one direction, you can call it "positive" gravity, and you're pulled towards the Earth. If you have "zero" gravity, you're not pulled anywhere, and just float. If you have "negative" gravity (anti-gravity), you are pushed away from the Earth. This doesn't mean you are feeling less force than the zero gravity situation, just that the force is pointing the other direction than you designated positive gravity.

Similarly, negative temperature is when the particles naturally settle uphill, rather than downhill, as it were.

Thank you, that made more sense than the article.

Does these mean that entropy death isn't a reality for the universe?

Approves!

I get the feeling that these 'below absolute zero' temperatures don't really exist. They are just part of the math in our currently less than perfect model for how the universe behaves. Measuring the temperature of a laser is meaningless since a laser is just photons and photons have neither mass nor temperature (although they can influence both of those characteristics in other bodies). Using a 'negative temperature' balances the math to make our model work.

Cave Johnson here. Those test subject wishing to make MORE than \$60, and dont mind us flipping your molecular state to one where cold objects become hotter, in the name of SCIENCE, go see the nurse on level 10. And please, before you go, wash any flammable grease out of your beards.

They will declare the cause to be "dark cold" like they do to cover up all their other math errors.

Uh, yeah. My white cell count!

That's COOL.

oh yeah, I went there.

ISO15693: Cave Johnson here. Those test subject wishing to make MORE than \$60, and dont mind us flipping your molecular state to one where cold objects become hotter, in the name of SCIENCE, go see the nurse on level 10. And please, before you go, wash any flammable grease out of your beards.

Bad news, test subjects. The Temperature Inversion test has been cancelled. We do, however, have a new test for you, testing Microwave Ray Emitters against abominable ice monsters. Grab a weapon from the racks on level 9 and follow the blue line down the stairs to level 10. You'll know when the test begins.

Colder than absolute zero = the temperature of your wife's feet when she gets into bed.

Negative on the Kalvin scale does not mean below zero energy. Absolute zero means there is nothing moving because there is no classical energy. Mainstream media shouldn't report on physics news because they don't understand it.

FTA: This unusual advance could lead to new engines that could technically be more than 100 percent efficient

Just like Lisa Simpson, they don't believe in the laws of thermodynamics.

also:

"Let's expend an extraordinary amount of energy to align atoms into a state wherein we can use them to produce more energy!"

I'd be very interested to see how it ultimately shakes out, but my first instinct on this is that given the expense (energy wise) of using lasers in a vaccuum static environment in order to attain the states they have means that there's no way they get more energy out of the system than they put in it.

You can do all manner of entertaining things with math, but going from what they've achieved to 'heat engines that are more than 100-percent efficient' in more than a theoretical model still seems pretty absurd.

palelizard: ISO15693: Cave Johnson here. Those test subject wishing to make MORE than \$60, and dont mind us flipping your molecular state to one where cold objects become hotter, in the name of SCIENCE, go see the nurse on level 10. And please, before you go, wash any flammable grease out of your beards.

Bad news, test subjects. The Temperature Inversion test has been cancelled. We do, however, have a new test for you, testing Microwave Ray Emitters against abominable ice monsters. Grab a weapon from the racks on level 9 and follow the blue line down the stairs to level 10. You'll know when the test begins.

Both of you receive 1/2 internet each for taking an old joke and making me laugh at it all over again.

Yeah...and I suppose we'll all have flying cars next, eh?

/obligatory...

madgonad: Measuring the temperature of a laser is meaningless since a laser is just photons and photons have neither mass nor temperature (although they can influence both of those characteristics in other bodies).

No, photons have energy, and a thermal distribution of photon energies corresponds to a temperature. The whole blackbody radiation thing happens when a photon gas is in thermal equilibrium with matter, i.e. they have the same temperature.

The weird part, as near as I can figure it, is that this "negative temperature" thing isn't the sort of temperature we're used to thinking about. Most of the time, we use temperature to describe the average energy of a bunch of particles. That has an absolute, inviolable zero: when the system of particles is in its lowest possible energy state.

The temperature they're talking about here isn't based on the average energy, but on the distribution of the various particles' energies. More low-energy particles than high-energy particles (which is how things settle down in equilibrium conditions) corresponds to a normal, positive temperature. More high-energy particles than low-energy particles requires a negative temperature to be plugged into the formula.

Energy distributions like that are non-thermal, i.e. they can't happen for a system that's in thermal equilibrium, but only when things are in flux somehow. Our normal concepts of temperature, heat flow, and such only apply to systems that are either in equilibrium or really close to it, so it's natural that applying them to other conditions produces screwy-sounding results. It's workable if you're meticulous about how things are defined, but you can see the sort of crap that happens when you let journalists loose on it.

So temperature is simply a 2s compliment integer?

stratagos: That article made my brain hurt. Where do they make the logic jump from "effectively a billionth of a degree below zero kelvin" and "engines that are more than 100% efficient"

Because despite their higher energy state, they pull energy from "colder" positive temperatures, so far as I could glean.

If the Super Bowl is the ultimate game, why do they play it every year?

wut?

So now Spinal Tap will have to crank it down to -11?

It's more like trying to assign -1 to an unsigned integer. It just loops back around to the top.

ISO15693: Cave Johnson here. Those test subject wishing to make MORE than \$60, and dont mind us flipping your molecular state to one where cold objects become hotter, in the name of SCIENCE, go see the nurse on level 10. And please, before you go, wash any flammable grease out of your beards.

Awesome. I read that in his voice, too.

+1

ThreadSinger: ISO15693: Cave Johnson here. Those test subject wishing to make MORE than \$60, and dont mind us flipping your molecular state to one where cold objects become hotter, in the name of SCIENCE, go see the nurse on level 10. And please, before you go, wash any flammable grease out of your beards.

Awesome. I read that in his voice, too.

+1

Cave Johnson automatically makes anything awesome!

/Lemons!

This is more proof that we live in a computer simulation. This is nothing more than an overflow error.

need a new temperature scale now dammit...

/one more conversion chart...

rogue49: need a new temperature scale now dammit...

/one more conversion chart...

We'll just make absolute zero one lower.

Maybe this leads credence to the theory will are living in a metastable false vacuum.

If so, screwing around with this is a bad idea.

I thought that when stuff gets really cold it coalesces into Bose Einstein condensates. So at negative temps are they still condensates?

I just want some goddamn exotic matter so I can make a traversable wormhole dammit!!

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