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Decay of matter?

  1. Sep 27, 2015 #1
    Hi,

    I have a question regarding decay of matter. Let's say I have a block of lead. Now imagine I sit it in a vacuum - given infinite time. What will happen to it - will it ever degrade or change. In another way does matter last forever?

    Also what is the correct physics term for what I am describing

    Thanks
    Ward
     
  2. jcsd
  3. Sep 27, 2015 #2

    Drakkith

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    Staff: Mentor

    I believe that unless proton decay occurs, then yes, it should last forever.
     
  4. Sep 27, 2015 #3
    If black holes can form by quantum fluctuations and there exists the smallest possible black hole that does not decay, then the block of lead will not last forever, it will eventually form a black hole instead.

    If black holes can decay, no matter how small, then the fate of the block of lead depends on the speed of expansion of universe (lol). Basically, the stable configuration will be an evaporating black hole surrounded by Hawking radiation in thermal equilibrium. The hole radiates particles and absorbs particles at the same rate. The equilibrium state can not be achieved if the universe expands so that the temperature of Hawking radiation constantly drops - in this case the ultimate fate will be single noninteracting particles flowing through space forever. Also, equilibrium can not be reached if the universe contracts, so that temperature rises.
     
  5. Sep 27, 2015 #4

    anorlunda

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    Science Advisor
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    The original question is not clear. Does it apply specifically to natural lead, or to any matter?

    Radioactive decay, also known as nuclear decay or radioactivity, is the process by which a nucleus of an unstable atom loses energy by emitting radiation. https://en.wikipedia.org/wiki/Radioactive_decay

    Via that process some nuclei decay into other kinds of nuclei. For example, one isotope of lead, 210Pb, decays into mercury or bismuth with a half life of 22.3 years. But other isotopes of lead (204, 206, 207, 208) are called "observationally stable" which means they don't decay. The most common natural forms of lead are the stable ones. That is what Drakkith meant when he said it "should last forever".

    You asked "will it ever degrade or change" The answer is sometimes yes, sometimes no, depending on what "it" refers to.
     
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