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A Reversibility of radioactive decay process?

  1. Jun 20, 2017 #1
    I viewed the answers to the non repliable post https://www.physicsforums.com/threads/is-radioactive-decay-reversible-in-time.673735/, but I have doubts. In particular, the last claim by nugatory: "the overall decay of the sample is as irreversible as the transfer of heat from a hotter body to a cooler one."
    Given that there is no heat inside the nucleus, and knowing that temperature doesn't influence half-life time in radioactive deacay of, let's say, a neutron or a tritium nuclid, we must agree that heat transfer here can be not more than an analogy.
    On the other hand, if the process can be reverted, we should get a dynamic equilibrium between nuclei and dacay products by putting protons and electrons in a gravitationally confined volume with enough kinetic energy (that is the same of high temperature). In that system we expect that the probability of decay in the collection of neutrons would be temperature dependent.
  2. jcsd
  3. Jun 20, 2017 #2
    Avodyne addressed that in the original thread:
  4. Jun 20, 2017 #3
    Thank you Anodyne, but I already read that. The equilibrium I was talking about, or striving to conceive, was exactly of the kind of nucleosynthesis. I'm questioning that is strange to think about a dynamic equilibrium that is an analogous of phase equilibrium in which the decay process is temperature independent whereas the reverse process is temperature dependent. You can have a perfect statistical balance among the two processess, of course. But what I miss is how the process continues inside the recombined/initial atom, without any thermal effect, while outside you have motion, temperature, kinetic energy. There is a sort of "gate" or interface between the two opposite processes which obstacles the principle of microscopic reversibility. Furthermore, if the original nucleus has no evolution, no processes inside, how could that lead to a precise statistical lifetime? I think that we have "vibrations" both inside and outside the nucleus, although of different nature: quantum fluctuations inside, thermal outside. Eventually, provided I'm interested in local time arrow, I believe time continuously flows in the same direction independently if entropy is increasing (a single neutron decaying, or many more neutrons decaying than forming) or decreasing (more electrons and protons back-forming neutrons).
  5. Jun 20, 2017 #4

    Vanadium 50

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    This sounds a lot like a personal theory. As far as conventional physics goes, Avodyne addressed that in the original thread.
  6. Jun 20, 2017 #5
    You seem to be tying heat to the mechanism that a nucleus uses to time its own decay. There are plenty here who can correct me if I'm wrong, but I think I can provide a more conventional explanation.
    Think tunneling. Imagine two tall hills with a small elevated valley between them. That high valley represents the state of the undivided heavy nucleus. That valley holds the nucleus in its unified state well above the much lower surrounding valleys. Normally, that would be the end of the story. But the state of the nucleus cannot be exact. It is subject to the Heisenberg Uncertainty Principle and has the potential to escape through the hills and from the high valley, to effectively tunnel its way out.
    So the timing mechanism you are looking for is not related to heat or to any activity within the nucleus. It is simply HUP - which includes a time component.

    Addressing the issue of equilibrium: It is certainly possible for the process to reverse, but the likelihood is low because the surrounding valley is so much lower than the high valley. Under some conditions, that surrounding valley can be very hot and thus very high, and under those conditions, these heavy nuclei can be formed.

    Hope this helps.
  7. Jun 20, 2017 #6
    OK, and decay time is inversely proportional to the energy barrier.

    Sure, that helped me a lot. But, at the same time it remembered me of attempts to relate Heisenberg's uncertainty to a sort of dissipative or sthocastic process occurring at a lower level than thermal. I can't manage the mathematics of that process: it is a matter of faith that everything in the Universe is vibrating. So, "tunnel effect" is the phenomenon, not the logical explanation of itself.
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