ending 1

 The potion slipped and the lab swayed as the asteroid's force controlled the whole lab. The 4 present selves cracked their bottles into bits of glass. The asteroid had crushed all the present selves and they died. Since there were no present selves, there were no future selves and with no future selves no robots with no robots there were no buildings. Without the buildings Washington D.C. was a wasteland forever and the asteroid destroyed other big cities making the earth died away.