I had a thought this morning about reincarnation, sort of. I thought, if the body has the same number of molecules before & after death, only energy has left the body. If energy leaves, where does it go? If a thousand people die at once, where will the energy go? Space must maintain an equilibrium of energy.
Will that energy get absorbed into matter elsewhere? Does it get sucked into the nearest black hole? Does the universe notice the energy change when just one person exits their body? I think it must.