Question: I saw this question somewhere in the Internet(I forgot the source) and I think this forum is a good place to ask it.

According to what I know, the atoms in a persons body are replaced every certain amount of years:
<https://skeptics.stackexchange.com/questions/18427/are-all-the-atoms-in-our-bodies-replaced-on-a-regular-basis>

Then, if a persons body atoms are replaced every x years, should the person be prosecuted today for a crime that he/she committed x years ago, when today that person is physically another person(different atoms)? 

And lets say hypothetically that 0.00001% of atoms are never replaced, should 0.99999% of the sentence in years be eliminated (the person is 0.00001% responsible for the crime) ?

This is a related question in the forum:
[Am I still the same person as I was yesterday?](https://philosophy.stackexchange.com/questions/2747/am-i-still-the-same-person-as-i-was-yesterday)

Answer: 
Arne Naess wrote many essays about the Self. In them, he argued for a concept called the Ecological Self, but along the way he used a series of phrases to challenge commonly held approaches to defining the self. Such class of phrase pairs looked like:

* I enjoy listening to Mozart.
* My body enjoys listening to Mozart.

Or

* I am my mother's son. ("daughter" if you are female)
* My body is my mother's son ("daughter" if you are female)

If one considers the pairs of phrases to not be *quite* identical, it suggests that "my body," i.e. the atoms in my body, are not quite exactly the same concept as "my self." Thus, replacement of the atoms in the body is probably not sufficient to be a change of self.
It seems to me that this is just a reformulation of Theseus' paradox. Plutarch notes in his biography of Theseus that the ship that Theseus and the other Athenian youths returned upon was preserved by the city of Athens through the ages. As various planks and rails rotted, they were replaced leading to the question commonly discussed among philosophers over whether or not the ship we have now is one and the same as the ship that Theseus returned to Athens upon.

Really the question at hand is the very question of identity. It's not an easy question to answer. A good starting place is the subtopic Understanding the Persistence Question over at the Stanford Encyclopedia of Philosophy in the Identity entry: <http://plato.stanford.edu/entries/identity-personal/#UndPerQue>