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Zaq comments on Timeless Identity - Less Wrong

23 Post author: Eliezer_Yudkowsky 03 June 2008 08:16AM

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Comment author: Zaq 10 October 2013 10:32:03PM 3 points [-]

Eliezer, why no mention of the no-cloning theorem?

Also, some thoughts this has triggered:

Distinguishability can be shown to exist for some types of objects in just the same way that it can be shown to not exist for electrons. Flip two coins. If the coins are indistinguishable, then the HT state is the same as the TH state, and you only have three possible states. But if the coins are distinguishable, then HT is not TH, and there are four possible states. You can experimentally verify that the probability obeys the latter situation, and not the former. And of course, you can experimentally verify that electron pairs obeys the former situation, and not the latter. This is probably just because the coins are qualitatively distinct, while the electrons are not.

But it seems that if you did make a quantum copy (no-cloning theorem be damned!) then after a bit of interaction with the different environments, the two would become distinguishable (on the basis of developing different qualitative identities) and start behaving more like the coins than the electrons. In fact, if you're actually using the lightspeed limit then the reconstructed you would be several years younger, and immediately distinguishable from what the scanned you has since evolved into. At the time of reconstruction, the two are already acting like coins and not electrons. Does this break the argument? I'm not really sure, because the reconstructed you at the time of reconstruction would still be indistinguishable from the you at the time of scanning, if you could somehow get them both around at the same time.

Bonus! The reconstructed you could be seen to have a very qualitatively different time-evolution. The scanned you evolves throughout its entire history via a Hamiltonian which itself changes continuously as scanned-you moves continuously through your environment. Reconstructed you, however, has a clear discontinuity in its Hamiltonian at the time of reconstruction (the state is effectively instantly moved from one environment into a completely different environment). The state of the reconstructed you would still evolve continuously, it would just have a discontinuous derivative. So I'm not really sure if reconstructed you would fail to pass the bar of having a "continuity of identity" that a lot of people talk about when dealing with the concept of self. My gut says no, but I'm not sure why.

Comment author: deciplex 27 April 2016 10:35:19AM *  0 points [-]

Eliezer, why no mention of the no-cloning theorem?

Indeed. It is disappointing to see this buried at the bottom of the page. I don't think the no-cloning and no-teleportation theorems have any serious implications for Eliezer's arguments for life extension (although, it might have some implications for how he anticipates being recovered later). But, it does have some implications for the ideas about identity presented here. Here is the relevant text:

Are you under the impression that one of these bodies is constructed out of the original atoms—that it has some kind of physical continuity the other does not possess? But there is no such thing as a particular atom, so the original-ness or new-ness of the person can't depend on the original-ness or new-ness of the atoms.

In fact, having read the entire QM sequence, I am not under the impression that I am made out of atoms at all! I am an ever-decohering configuration of amplitude distributions. Furthermore since I know my configuration can never be decomposed and transmitted via classical means, I also know that the scanner/teleporter so-defined can't possibly exist.

Now, if you want to talk about entangling my body at point A, with some matter at point B, and via some additional information transmitted via normal channels, move me from point A to point B that way - now we have something to talk about. But the original proposition, of a teleporter which can move me from point A to point B, but can also, with some minor tweaking, be turned into a scanner which would "merely" create a copy of me at point A, is an absurdity. It is impossible to copy the configuration that makes up "me". The original classical teleporter kills the people who use it, because the configuration of amplitude constructed at point B can't possibly match, even in principle the one destroyed at point A.