If a substance is said to have a half-life, doesn't this imply that it is eternal?

If I take 100 divided by 2, 50 divided by 2, 25 divided by 2, etc. I would never reach 0. If a radioactive element has a half-life, does it ever really go away? Do I have a half-life?

This question has haunted me for years, any illumination would be appreciated.

Well, sorta yes and sorta no. Eventually, you’re going to get down to only one atom left, and it’s going to only last for a certain period of time. Remember, the half-life is an average, not a rule. As for whether “you” have a half life, only certain elements do, and only radioactive ones. There are isotopes in your body that are radioactive (like C14 (C12 is the regular, not radioactive version of Carbon)). These elements can be used to find out roughly how long ago you died by extrapolating backwards from how much is left in your body, since they have known half-lives.

Zeno does physics!

It should be noted that C14 dating is only good for so long (about 40,000 years IIRC). For stuff older than that there’s not enough radioactivity to measure and they have to use other methods of dating.


I was going to say that.