I stumbled upon this sentance while writing up a physics lab. It expresses the concept wonderfully:

:happycat:

edit: actually this is more likely to fuck with engineers/people who know some physics. Still, hehe

Well, that's a gorgeous sentence. I feel inferior already. :( Care to provide some links to ease the pain, or a bit more explanation?

That indeed fucks with my head.

It's like the signal generator i was using the other day, which was putting out -10KHz.

it sounds to me like the whole glass isn't half empty its half full thing...a different way to say the same thing...

Oh dear, it wasn't meant to make anyone feel inferior, more to pander to the stereotype of oddball scientists coming up with crazy theories that defy belief...

Basically it all comes down to what we define temperature as. Everyone knows that hot things are hot and are at a higher temperature than cold things that are cold, and that heat flows from hot things to cold things, cooling the hot things and warming the cold. Unfortunately such a definition is not quite definitive enough for physicists (I believe it does work for engineers though :P).

As far as (an ideal) gas is concerned, temperature is a measure of the mean kinetic energy of the particles - basically how fast they are going.

If the particles can interact with each other and store potential energy in some form this has to be taken into account too. In statistical physics temperature is defined by: 1/T = dS/dE, where T is temperature, S is entropy and E is energy. Entropy is basically a measure of disorder, or the number of states available to a system.

In the nuclear spin system I was looking at there are only two states available to the nucleus, spin up and spin down. If a magnetic field is applied these states have different energies. The energy of the system is then given by the number of nuclei in each state - the lowest possible energy is when all the nuclei are in the spin down state, the highest when they are all spin up. An intermediate value occurs when half are spin up and half are spin down.

Let us have a look at the graph of dS/dE (how the disorder of the system changes with the addition of energy). Starting at the lowest possible energy we only have one way of arranging the system - all spins down. This corresponds to the lowest possible entropy. If we add some energy to the system some of the nuclei will 'flip' and have their spins up. There are many more ways of arranging this system so the entropy increases, as does the temperature.

As we add more and more energy to the system the temperature continues to increase, just as it would if you were heating a pot of water. All is well. This carries on until we hit the point where half the nuclei are spin up and half are spin down. Hence dS/dE = 0
...
1/T = 0
...
T = infinity
...
disaster.

As we keep adding energy the entropy begins to decrease. dS/dE is negative, as is temperature. So you can see when the system has negative temperature, it actually has more energy than it did at positive (or even infinite) temperature. This carries on until the system has maximum energy (it canne take it any more, Captain!) and we hit negative zero.

The quote itself was from wikipedia

*sees the light dawning over the horizon*

I think I just gained an IQ point, el bronto. :bowdown:

thank you for clearing that matter up for me...now i feel significantly more intelligent... :hmm:

Only 1 IQ point? :hmm:

And save the :bowdown: for the people who invented it, any old monkey can learn it :wow:

I'm counting on you to eventually get me up into double figures. :wow:

Heh, I'll start writing a column

I leveled up.

I'll stick with thermodynamics. BTW, an irish thermo lecturer would rule.

Hehe, level up. With a burst of insight templar34 becomes STAGE 3 PHYSICS!

You'll stick with thermodynamics? And an Irish thermo lecturer? I don't get it

Can you imagine an Irishman saying Thermodynamics? Entalpy?

Thermal is one of really only two areas I enjoy, and I like it more than electronics, currently

arts students cant count.

science students cant read.

So....

Where does that leave Commerce students :P?

I knew some smart arse would ask that.

It depends which kind of Commerce student. Accounting and Finance come under science...so they cant read.
Marketing students can't do anything.
Economics students can do everything.

The rest don't count.

El Bronto, thank you. That is far more interesting than what I'm doing in thermo right now (Stage II Chemical Engineering). However, I'd like to see you apply that...


Also, I heard that commerce stdents are good at sleazing

I'm applying it right now, in a monster stage 3 physics lab known as nuclear magnetic resonance (NMR). NMR is incredibly useful, physicists invented in cause they could, then the chemists realised they could use to analyze substances, then the biology type people got ahold of it and used it in what they call magnetic resonance imaging (MRI) to look at the insides of people (naughty, naughty).

The way thermodynamics is taught I find incredibly boring, thought Templar34 seems to like it, although he implies he likes electronics too :shrugs:

Economics students can do anything - one nearly became prime minister the other day :ph43r:

That is why I am going to take over the world.

I believe the term is 'stealth man-whoring'. It is an art which cannot be taught ny any department.

No, sloanie's right. I was born like this.

commerce students can't think. :P

commerce is what im going into due to finding science boring and hard...while commerce is boring but easy...

hannoir, arts students dont neeeed to be able to count. :angry:
besides, it makes band statement time a whole lot less painful when you confuse your +s with your -s and your 9999s with your 12s.

i often confuse my -'s with my +'s when it comes to grades...in that i always get +'s...but never minuses...