Just because physics doesn't have a notion of identity, doesn't mean there is no such thing.

Identical particles have different identities because they have a different location in space-time. The location in space-time creates the identity.

There's also a problem with the math of your claim. They can't "be the same particle" if you can have two of them. 1 != 2

> Just because physics doesn't have a notion of identity, doesn't mean there is no such thing.

How is that not exactly what that means?

Identity, like beauty, fun, and spiciness, is[1] something that's built on physics, not requiring a fundamental property, just as asking how much spiciness an electron has is futile.

[1] Well, presuming it actually does exist as something other than confusion, which I'm not currently arguing, though I'm sympathetic to the notion.

Beauty has physical structure on a couple levels. You can either talk about certain synapses lighting up (or whatever happens in the brain when someone experiences beauty) or you can talk about facial symmetry and 1.618.

Fun is an extremely vague notion, I'm not sure what it means or if it even has a consistent set of synaptic patterns (or whatever), but I think that's probably because people don't use the term consistently (or are confused, etc., as you say).

Spiciness is absolutely purely chemical.

I think the problem there is with the first half of that statement,

> Just because physics doesn't have a notion of identity

I inferred that the intended meaning was "Just because the field of physics has no notion of identity". Obviously in philosophical and sociological circles there is absolutely a concept of identity.

Because physics is not done?

You should read the Quantum Physics sequence I mentioned above. There is no Royal Road, and the whys and hows just cannot be explained in a few lines[1]. If you want a short-cut nonetheless, try here[2] to understand what is a configuration space, then proceed there[3] to understand what "no identity" really means. I won't repeat Eliezer here, you really have to follow the links.

Now I did made some language abuse.

First, there is no such things as a particle at the basic level. I mean, there are particles, but in the same sense that there are houses: particles are not the fundamental stuff, they are made up of the fundamental stuff, just like houses are made up of bricks.

Second, It is possible to test whether two situations are the same, or not. And I don't mean "nearly the same", I mean exactly the same. The difference is rather drastic: in one case you end up with |x|²+|y|² (where x and y are two complex numbers), and in the other case, you end up with |x+y|².

Third, there are no labels attached to particles. The universe is not like "photon A here, photon B there". It is more like "photon here, photon there". We know that because of my second point: there is just no difference between "photon A here, photon B there" and "photon B here, photon A there", it is the same configuration.

Now, when you move a particle from point A to point B, those are certainly different configuration. (So you do have a point). On the other hand, the way you move the particles doesn't matter in the slightest, as long as the end result is the same: having the particle at point B.

Well, the same goes for a human. Flying from London to New-York doesn't destroy your identity. The only thing that matters it that you end up in New-york. So, whether you took the plane, or have been wired across the internet just doesn't matter. You end up in New York.

Now, sure there is some difference: locally, you are the same. But the world around you is different. So this is a different configuration[4]. The plane didn't fly, computers did some more work, bandwidth got consumed… But that doesn't sound like the kind of difference that destroys your identity, even intuitively. I mean, by writing this text, I have a much greater influence over your than the motion of a plane could ever have (unless you're in it, or watching it). And I don't destroy your identity.

Now that's about it. Those who hunger for more should really read the whole Quantum Physics Sequence.

[1]: http://lesswrong.com/lw/kg/expecting_short_inferential_dista...

[2]: http://lesswrong.com/lw/pi/classical_configuration_spaces/

[3]: http://lesswrong.com/lw/pl/no_individual_particles/

[4]: http://lesswrong.com/lw/pf/distinct_configurations/

>You should read the Quantum Physics sequence I mentioned above. There is no Royal Road, and the whys and hows just cannot be explained in a few lines.

Life is short.Just read Volume III of Feynman Lectures here

http://www.feynmanlectures.caltech.edu/III_toc.html

Bookmarked, thanks.

The target particles in quantum teleportation are sort of a canvas on which to paint the properties of the original particles. After teleportation, the two entities will be indistinguishable.

However, I do not think it means you are the same person. Currently, quantum teleportation destroys the original copy. For the sake of philosophical argument, suppose it did not. Then that new person would be conscious independent of you. Clearly, you are not that person.

Now imagine your particles becoming destroyed. You are dead. He is alive. He is not you, even though it would be impossible to tell that he was not you.

I think the whole discussion doesn't lead anywhere. We're trying to bend the ideas of self, continuity and sameness to our quite limited imagination.

Let's take the teleportation example: my rebuilt self is just as much "me" as the original was (or still is, should the device keep it intact) -- all atoms are in exactly the same place, and what's crucial, the memories and mental characteristics are preserved. It's not my clone (where only the DNA is the same), it's the exact replica. Doesn't matter that it's built from freshly assembled atoms, since our bodies continuously assimilate new atoms and shed old ones anyway. In that we're more resembling a wave on the ocean than a Luke Skywalker's lightsaber prop, where it actually counts that it's the exact set of atoms that Mark Hamill wielded on set. If you care about memorabilia anyway.

The two existing duplicates of me are obviously not "the same me", but nobody should expect them to be. They both are a continuation of myself. Like the aforementioned wave, I'm not my atoms and their configuration, I'm the continuity of their ever-changing state.

.......

When a cell divides, does it cease to exist? If so, at which point exactly? Are the two newly created cells the same cell as the one that was there before? Are they a half-cell each, even though they both are full cells now? Is one of them the original cell that gave half of its matter to create an offspring? Would everything be back to normal if one of them ate the other one and we could say that the original cell just performed a crazy transformation, but it's still the same cell (the same atoms, chromosomes and all)?

These questions might seem reasonable, but I think they stem from our mistaken desire to qualify and label things. Still, the reality isn't limited to our understanding of it.

So if a copy of you were made, you would be ok with swallowing a suicide pill?

If you are asking this question after the copy was made, then the mere fact that you would be asking that question to the original, means that the original diverged from the copy. The copy was not presented with that offer (to swallow pill) and the thought processes and synaptic impressions in their brains started to diverge! They are no longer identical.

The best scenario would be if there were no concept of choice at all. Not even before the copy were made. Not even the awareness that as part of the cloning either the clone or the original would die is good enough, because you are still asking me to make a choice.

The ideal case would be I am awake today, go to sleep and tomorrow either me or my copy would wake up.