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Our life-time is negligible, compared to that of unstable nuclei with half-lives of billions of years.

How, then, are these half-lives estimated, if you may never even witness a decay. It's like estimating the probability of a popcorn kernel popping, after one of the 200 in a pan has popped.

Would it be done over, say, a decade, with a massive amount of the source constantly monitored by a gygameter? Wouldn't the data still be inconclusive?

Is it estimated other ways, such as by examining the relationship between the composition of an atom and its half-life, to extrapolate larger half-lives? Comparing the quantities of the nucleuses isotopes found in nature, to extrapolate?

-- How on earth could scientists know that Lead-204 has a half-life 10,000,000 time longer than the age of the universe ~14,000,000,000 so: 140,000,000,000,000,000 years.

Qmechanic
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Tobi
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  • @Countto10 That's not a duplicate... "Logically, shouldn't it take 2,865 years for the quarter to decay, rather than 5,730?" Does that read similarly to anything I've asked? – Tobi Mar 02 '17 at 13:38
  • @Tobi It kind of is though. But it isn't clearly so -- it doesn't use the exact same words you do, but the answer to that other question is the same answer to yours. – tpg2114 Mar 02 '17 at 13:41
  • The question they ask is "How do half lifes work" followed by "...Logically, shouldn't it take 2,865 years for the quarter to decay, rather than 5,730?" – Tobi Mar 02 '17 at 13:42
  • Very much irrelevant to this question about how half lives are estimated way beyond our life time. Does that not make sense to you? – Tobi Mar 02 '17 at 13:43
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    And your question ultimately boils down to "How does half-life work" and the answer is the same. There is a whole lot of atoms in a small sample of material, and by observing them and counting how many undergo changes, you can figure out the half-life. If there is 10^22 atoms in a sample, you don't need to wait 10^18 years to see a change. – tpg2114 Mar 02 '17 at 13:44
  • "How does a half life work" was about the meaning of a half life. The question poster was evidently confused by how it was used to model decay. My question on the other hand is unrelated, in that, it's speaking about how the values are estimated. Yes, someone may have gone on a tangent, in one of the many answers there, that related to this, but, this question is in no way a duplicate. – Tobi Mar 02 '17 at 13:48
  • Is "how is charge estimated?" a duplicate of "how does electrostatic repulsion work?" – Tobi Mar 02 '17 at 13:50
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    Possible duplicate of How do we know that some radioactive materials have a half life of millions or even billions of years? – Jon Custer Mar 02 '17 at 13:51
  • That question is most probably a duplicate. My question being down voted is sp childish... – Tobi Mar 02 '17 at 13:52
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    Move on, as in? I successfully got the answer to my question, even with the pedantry/instigative nature, typical of stackexchange forums – Tobi Mar 02 '17 at 14:02

1 Answers1

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Because there are a lot of atoms. Lets take the example of lead 204. If we take 1 Mol, which is 204g we have $6×10^{23}$ atoms. You say half-life is $140×10^{15}$years which is around $4×10^{24}$ seconds. So in a crude estimation you still should have around 1 decay every ten seconds. In order to find this, you look for the outgoing radiation, not for the decay product.

John Dumancic
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lalala
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