Probably a very stupid question, even may deserve to be downvoted, but I have always wondered: Hypothetically, let's say somehow tomorrow I die in an accident. Now lets say that after a long time (e.g. centillion of years) for one reason or another the cells that made up my body -right before I died- are part of a new body arranged exactly the same doing the exact same functions. My questions are:

1) It is possible? -Possible in the sense that atoms that are cremated tomorrow or ate by worms, can they go back to their previous chemical state?-

2) Am I the same person? Not philosophically, I mean are there in my brain the same synapses? or are other variables to take into account? (I guess this one is more about neurochemistry than chemistry)

Let's not discuss the likelihood of happening, at least not much, because time is infinite one can argue that it may be bound to happen. But time being infinite or not and related questions may be more of an cosmology issue.

  • 1
    $\begingroup$ I would say this is outside the scope of chemistry. You might be able to stretch and say it is a biological question, but I think it is more suitable as a philosophy question. I don't think science has an answer on whether the same arrangement of the same atoms would constitute the same person. We have yet to achieve cloning or understand the brain on anywhere close to the level to say the collection of cells would be the same person. $\endgroup$
    – Tyberius
    Mar 18, 2017 at 3:21

1 Answer 1


Let me start from the bottom up: If we assume the earth as a closed system, i.e. exchange of energy with the surrounding space is possible, but exchange of matter impossible, than naturally our body contains atoms previously present in other form of matter. Already our breakfast is matter we incorporate, subject to chemical reaction (digestion), and eventually excrete in one form, or an other. Hence it is likely that we contain some atoms that once constituted a mammoth, or a dinosaur, or by your tomato in the back yard.

Digestion often splits the larger molecules present in our food into smaller ones. This eases transport of matter across membranes, for example. Think of proteins de-constructed into amino acids; our organism uses the smaller to build new proteins in need.

Beside chemical degradation as in aforementioned example of the proteins, digestion includes physical degradation, too -- chewing food, for example increases the surface area the chemicals responsible for digestion may access. By both means of action, physical and chemical degradation, entire cells face only a tiny chance to remain intact "as such". It is more likely that they are dismantled, are split into their constituents, eventually -- as molecules -- harvested in the ways briefly mentioned earlier.

To sum up: so far there is no evidence a synapse of yours will be recycled, maintaining the original form and function, to find its way back as synapse in an other brain, similar to a spare tire. Atoms of yours however, as easily they entered your body, eventually will leave you; at their pace.


Not the answer you're looking for? Browse other questions tagged or ask your own question.