# What isotope has the shortest half life?

Question:

What isotope has the shortest half life?

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One question at a time please. The question of half-life constantness has been addressed on the site already (see also the "related" question of the link), and redefining the time base would be a "discussion" and as such "not a real question". –  dmckee Jul 25 '12 at 15:17
@dmckee What SE site would you suggest for the redefining time question? Philosophy? (sounds wrong to me but....) –  Event_Horizon Jul 25 '12 at 15:46
All Stack Exchange site that I am familiar with ban "discussion" type questions, so I wouldn't suggest any of them. I'm not, however, intimately familiar with all of the sites so you could read their FAQ and look in their meta posts to figure it out. –  dmckee Jul 25 '12 at 15:50
@Event_Horizon: you could repose as something like "What would be the advantages/disadvantages of changing our time system?" and post it here. If you have specific changes in mind, that would help define the question further. –  AdamRedwine Jul 25 '12 at 18:14

The question is ill-posed.

To begin it should be "*What isotope has the..." and even then the answer is "We don't really know, as there are some we have produced too few times to have an accurate measure for but they sure don't live long." Looking at the low-mass end of the periodic table I find some described in terms of the linewidth---which means really short.

Isotopes with halflives measured in 10s of seconds have been put to use from time to time. And the shortlived low-mass isotopes are useful in calibrating underground neutrino detectors.

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@ArnoldNeumaier Er...Yeah. You know how it is, trouble with things like basic multiplication. $24*4 \approx 100$ not $1000$. Thanks. –  dmckee Jul 25 '12 at 18:00