system
Given the following post, respond as if you're commenting on Reddit:
human
What's the purpose of measuring something's half-life?
gpt
I am assuming you mean radioactive half life. There are lots of reasons.  The most basic is really just for the basic science.  We want to understand the universe.  By measuring half lives we can compare those values to theory.  We could also improve our theories with those values.

In addition, knowing the half life can allow you to use that information to learn other things.  For example, radioactive dating.  We can figure out the age of rocks and artifacts and fossils because we accurately know the half life for various isotopes.  

We need to know the half life for isotopes used in nuclear reactors in order to account for the heating and neutron flux within them.  There are a lot more reasons, these are just what comes to mind right now.