# Absolute Zero or Uncertainty Principal?

1. Aug 12, 2006

### Dropabomb

A few weeks ago, I was wondering around my school when I realized that at absolute zero, Heisenburg's Uncertainty Principal may break down due to the non-existance of energy among subatomic particles. Later, while I was researching the topic, I found a few books that covered this topic and interpreted this as the evidence that absolute zero can not be reached since under no circumstances should HUP break down. However, an article published by the NewScientist magazine stated that "Even if the universe itself froze over and its temperature plunged to absolute zero, zero-point vibrations would still be going strong, propelled by energy from empty space." Which contradicts my previous statements. So, can anyone tell me which statement is more accurate. If neither statements are at all accurate, can someone provide me with a more accurate picture regarding this topic?

2. Aug 12, 2006

### ZapperZ

Staff Emeritus
Look into a QM text at a quantum harmonic oscillator. Is the lowest possible energy zero, or is it a finite, non-zero value?

Furthermore, the specific heat of nobel gasses, for example, exhibit the deBoer effect in which the zero-point energy correction kicks in.

Zz.

3. Aug 13, 2006

### HallsofIvy

Your first statement "at absolute zero, Heisenburg's Uncertainty Principal may break down due to the non-existance of energy among subatomic particles. " is wrong; it works the other way- because of Heisenburg's uncertainty principle you cannot have "non-existance of energy" and so particles do not stop at "absolute zero". The other two statements, that absolute zero cannot be reached and that even at absolute zero there is still zero-point vibrations are not contradictory, they are just different ways of saying the same thing. The first interprets "absolute zero" as meaning no motion and so it is impossible to reach absolute zero. The other interprets "absolute zero" as the lowest possible temperature and so says that at absolute zero there is still motion.

4. Aug 13, 2006

### Dropabomb

Oh

Oh, I see, thanks for the clarification.

5. Aug 13, 2006

### samalkhaiat

6. Aug 13, 2006

### ZapperZ

Staff Emeritus

7. Aug 13, 2006

### samalkhaiat

8. Aug 13, 2006

### Schrodinger's Dog

As I understand it it's hypothetical but supported by theory, which is somewhat unusual, but not in physics,we assume that these things cannot be reached, but we have no idea why exactly, and we can make suppositions based on this, regardless of the fact that there is no evidence. Essentially we assume, we have no real idea, so we take assumption as fact sometimes, because our actual knowledge is lacking. As always this is a suposition, if you can prove that we cannot reach absolute zero absolutely, do so.

Personally I don't get it, it seems counter intuitive to make bold that it cannot be reached. Often the case, someone comes up with an idea it's right, without any regard for logic.

9. Aug 17, 2006

### juju

At absolute zero a system is in its lowest possible energy state. That state need not be zero.

juju