# Would any physical event happen at absolute zero?

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• Gerinski

#### Gerinski

For example if we could bring a radioactive atom to absolute zero, would it still be subject to the random radioactive decay? Or would absolute zero inhibit the normal half-life decay of the element?

Perhaps in other words, would absolute zero inhibit the elapsing of time?

As I understand it, there IS no such thing, physically, as absolute zero but I don't consider that a complete answer to your question so I hope a more knowledgeable member will jump in here.

For example if we could bring a radioactive atom to absolute zero, would it still be subject to the random radioactive decay? Or would absolute zero inhibit the normal half-life decay of the element?

Perhaps in other words, would absolute zero inhibit the elapsing of time?

Nah... I'm not sure about radioactive decay (even though I am pretty sure it wouldn't be affected at all), but there are many events that can happen in absolute 0, such as gravitational interactions between bodies, etc.

Nah... I'm not sure about radioactive decay (even though I am pretty sure it wouldn't be affected at all), but there are many events that can happen in absolute 0, such as gravitational interactions between bodies, etc.
So, you believe there IS an absolute zero, physically. I've read here on this forum that that is not the case.

For example if we could bring a radioactive atom to absolute zero, would it still be subject to the random radioactive decay? Or would absolute zero inhibit the normal half-life decay of the element?

Perhaps in other words, would absolute zero inhibit the elapsing of time?
If you are considering a single atom then temperature is not a meaningful measure. Temperature is a statistical property of large collections. It is [pauses to look it up] the partial derivative of internal energy with respect to entropy. Entropy is not well defined for a single atom.

Delta2
Curie & Kamerlingh Onnes, 1913, "The radiation of radium at the temperature of liquid hydrogen"
suggests that radiation (alpha) is not affected by temperature.
http://www.dwc.knaw.nl/DL/publications/PU00013080.pdf
Do more recent experiments confirm or deny that claim, I guess more googling is in order.

Would it possible to use such evidence to determine what would happen at absolute zero?
Knowing of course that, physically, we can come close to absolute zero, but never quite at it ( as phinds eludes to ).

So, you believe there IS an absolute zero, physically. I've read here on this forum that that is not the case.

No, there isn't. I'm theoretically speaking.

A lot of systems are solved at T=0. In fact, in most cases, it is SIMPLER to solve it at T=0. So yes, things DO happen, theoretically and in principle, at T=0. Tunneling can occur at T=0. Conduction electrons are non-local at T=0. etc... etc.

Zz.

Delta2
So if I understand well, the elapsing of time in fundamental physics systems is completely independent from temperature. That was actually the meaning of my question, I know that many macroscopic systems slow down their "normal" evolution if we cool them down. I wanted to know if fundamental physics processes are also slowed down or not by lowering the temperature of the system as close to zero as it is in principle possible.

I understand that the answer is "no", fundamental processes such as radioactive decay, decoherence, tunneling, particle interactions involving emission and absorption etc will still happen at the same rate even at absolute zero + the practical physical limit.

Thanks.

Um, yeah, why would they be dependend on temperature?

And how would you expect time to run at one rate in the universe just because it was a different temperature than other parts of the universe?

Yeah I guess you are right. I guess I had some intuitive feeling that some physical processes slow down with extreme temperature drop, but these may be only those processes which are mediated by kinetic energy of some sort, like food rotting, many chemical reactions, biological aging etc, while more fundamental physical processes may not be subject to temperature at all.

Thanks for the replies.

A possible decay is not affected by temperature I guess, because it only depends on the mass of the particle that decays and not on the average kinetic energy of a system of particles.
I think what is affected by temperature is the particles' interactions [because cross sections depend on the energies-->so temperatures]. An example is the evolution of the Universe, where some interactions were possible at the first stages and became 'impossible' as the it cooled down.

I can't imagine any reason the fundamental forces stop "forcing" at T=0.

Yeah I guess you are right. I guess I had some intuitive feeling that some physical processes slow down with extreme temperature drop, but these may be only those processes which are mediated by kinetic energy of some sort, like food rotting, many chemical reactions, biological aging etc, while more fundamental physical processes may not be subject to temperature at all.

Thanks for the replies.

Oh OK then!

Not to mention radioactive decay will increase entropy. Entropy implies motion, which implies temperature.

Not to mention radioactive decay will increase entropy. Entropy implies motion, which implies temperature.
When you're digging this deep under the covers, it is not clear that a definition of temperature in terms of average energy per degree of freedom is appropriate. But then I've never taken a thermo course in my life, so I may be well off base.