# Less than 0 kelvin? Meaning of temperature

by .ultimate
Tags: kelvin, meaning, temperature
 P: 41 Zero point motion is predicted to persist to 0K. This energy cannot be radiated or lost any other way because there are no lower vibrational states available. But, the remaining motion occurs on a scale that is relatively small with respect to atomic sizes. The time-averaged atomic position remains fixed. The Lewis and Randall definition of 0K is that the entropy also be 0 and the substance be in a pure, perfect, crystalline state. As you get close to 0K, unpaired electron spin or nuclear spin can complicate matters, because mixtures of spin states can be obtained in the absence of a perturbing applied field. -Jim
P: 45
 Quote by ZapperZ That is what happens when light "disappears" when it hits objects.
If you say all the EM radiations carry energy. How can the energy 'dissapper'? Isnt that violation of Enery-Mass equivalence

 Not it doesn't. You are forgetting one half of this important equation - THE NATURE OF THE RECEIVER.
All matter is supposed to be made of same material. And What do you mean by 'nature' in atomic terms.

 The TYPE of material can also dictate if em radiation of a certain wavelength can be absorbed. No material has an infinite bandwidth of absorption. Your skin is obviously transparent to x-ray, which has a higher energy than visible light which is absorbed by the skin and turned into heat.
Well, this is purely hypothetical. X-rays are not absorbed by skin neither by bones. I recently postulated the reason for reflection of light

Size of wavelength of Visible radiation = of order of $$10^{-7}$$
and size of whole atom = $$10^{-10}$$
Size of nucleas = $$10^{-15}$$
Empty space = $$10^(-5}$$

Hence the EM wave will not penetrate through the atom, and the photon will be reflected as such.

You can apply tjhis to the above scenario, X-rays can penetrate through the skin cells but not bonemarrow.

 Atomic or molecular KE or lattice vibrations, the SAME way it is defined in thermodynamics!

Fine that Heat is considered to be molecular Kinetic Energy, But how can it be 'lost' as radiations?

Zzzz. (sleeping)
Mentor
P: 27,563
 Quote by .ultimate If you say all the EM radiations carry energy. How can the energy 'dissapper'? Isnt that violation of Enery-Mass equivalence
Read again what I said. I said the "light disappear". The FACT that I then said that it has been turned into heat means that the energy in that light has been converted in another form of energy, which is heat.

 All matter is supposed to be made of same material. And What do you mean by 'nature' in atomic terms.
Then you must have not read the FAQ that I have written and asked you to read. Consider the following: Graphite and Diamond are both made up of carbon atoms. Yet, they can't be any more dissimilar. That alone is enough to show you why what you wrote isn't complete.

 Well, this is purely hypothetical. X-rays are not absorbed by skin neither by bones. I recently postulated the reason for reflection of light
Careful with your speculative post and re-read the PF guidelines that you have agreed to.

Furthermore, you missed the point. I was debunking your idea that the higher the energy of em radiation, the most that energy will be absorbed. X-ray has a higher energy per photon than visible light, yet it isn't absorbed by skins the way visible light is.

 Size of wavelength of Visible radiation = of order of $$10^{-7}$$ and size of whole atom = $$10^{-10}$$ Size of nucleas = $$10^{-15}$$ Empty space = $$10^(-5}$$ Hence the EM wave will not penetrate through the atom, and the photon will be reflected as such.

 Fine that Heat is considered to be molecular Kinetic Energy, But how can it be 'lost' as radiations? Zzzz. (sleeping)
This is getting convoluted. I suggest you understand one part at a time before delving into another, and certainly before asking about "negative temperatures".

Zz.
P: 32
 Quote by haiha I think there's no concept of vacuum's temperature at least for classical physics. Because temperature measures the movement and/or oscillation of particles, so no particles mean no temperature. It is like you say of the speed of a car, but if there's no car, the speed of nothing is meaningless. I am not sure if in modern physics when they say the vacuum is not nothing, but somethingl, the temperature concept can be applied.
Just a thought. - space is a positive energy form +Ey plus a negitive energy form -Ey (y being qty) thus expressed Ey-Ey. It's not the some as zero. Conceptually it's different.

Quantum geeks have done experiments to support this "negative energy" or "antimatter" (same thing by definition) and concluded it is actually "positive energy" (matter)

If energy can't be created or destroyed and doesn't have geometric origins (time and place) It follows that it can exist independently of space and time. Defying any absolute zero of time space or temperature.

My muse is,

Is this "positive" energy outside added to equal "positive" energy inside (our universe) a possible explanation for why Vacuum has no temperature as opposed to 0 temperature?
P: 35
 Quote by .ultimate If tempertaure means the movement of particles, Can tempertaure be below 0 Kelvin? I mean no movement, vacumm
Yes, I think the same...
P: 2
 Quote by .ultimate Size of wavelength of Visible radiation = of order of $$10^{-7}$$ and size of whole atom = $$10^{-10}$$ Size of nucleas = $$10^{-15}$$ Empty space = $$10^(-5}$$
I suggest you go learn some maths first too, how can the empty space inside an atom be greater that the size of the atom itself?....

anyway...