Since the universe was 10-5 seconds old, when the hadrons formed. ;^) ========================================================
Well, if you can't be any more specific than that....
</sarcasm mode>
Your reply to PH was simply delightful; succinct and chock-full of fascinating info.
Well, my question was answered, that's for sure. As for that zinger about the age of the universe ... yeah, it was pretty good.