hormone testing was first and can work from 9 days (eggs hatch at day 21). Optical means (tend to work at a later point in the process around day 13-15), includ

hormone testing was first and can work from 9 days (eggs hatch at day 21). Optical means (tend to work at a later point in the process around day 13-15), including various forms of spectroscopy (NMR, IR, etc): shine a light at the egg and look for differences. Egg should be absolutely fine, but there will be a chick in there, so if you wanted to eat it like an egg, you might end up closer to balut than you want / expect.