Yes, of course: one of the twins. You assume that there are two for a significant time.
Suppose you have two cents, identical right down to the last atom. I destroy one. What have you lost? 1 cent.
Now suppose you have one cent. Within an imperceptibly short moment of time, I copy that cent down to the last atom and destroy the original. What have you lost? Nothing: you had one cent, you still have one cent. You never had two cents in any meaningful way.
Except objectively. Your argument is that if I can't perceive something exists then it isn't destroyed. But though I may not realize I had that second cent to lose, that doesn't mean it hasn't been lost, objectively, to the universe, regardless of whether I realize it or not, right? There are things happening all over the universe that are imperceptible to me. Do you want to argue that they're not really happening? Because according to this logic, which I will now call the
Principle Fallacy of Subjective Ontology, they're not. (Btw, apologies for my use of the phrase "have we lost anything?" in the bit you quoted; I meant what have we lost [objectively], not what have we lost from our limited human point-of-view, which objectivity always trumps; a better phrasing would have been "what has been lost?")
Suppose you had a computer file that is somehow important to you, for example it is a photo of your grandmother. You copy it. Now you have two identical files. If you delete one, have you lost something? Yes; you lost one copy. Because for some significant period of time, you had two copies.
Now suppose you have one computer file and you are going to "move" it. You can do this in one of two ways: either by changing the name of the path so that it appears somewhere else on the disk, or by copying to another place and deleting the original. Assume that both take an imperceptibly short moment of time, and you may not even know which method the computer will use. You started with one picture of grandma, and you ended up with one picture of grandma in another place. Have you lost anything? Does it make any difference which method is used? I'd say no.
Okay, this is a somewhat different analogy, i think. Let's see: "moving" computer files may be done in two ways: copying the file physically from one sector to another, or renaming the path to the file. Does it make any difference which method is used? Subjectively, as a computer user, not really; subjectively, as a computer programmer, yes (or it should at least, if I'm a good one); objectively, of course (the universe never misses anything: the method used determines the physical state of the computer). So I'd disagree. It may not make any difference to the user, but it certainly does to the physical state of the computer.
Most SciFi teletransporters are supposed to work similar to the copy and destroy method, though many presume that the destruction occurs before the reconstruction even begins, which means that at no moment in time are there ever two identical travelers.
Though objectively a destruction has occurred; kind of significant, especially to the being being destroyed ("being being" -- awkward wording, but fits this thread).
The transporters in Star Trek are sometimes claimed to use a method more similar to the path rename; the travelers supposedly consist of the same atoms as they started with, only shifted in space. This has apparently never prevented anyone from being copied, merged with others or turned into their younger selves, but if both methods work as intended, is there any significant difference between them? I'd say no: there is one you before transfer, and one you after transfer.
But there's the rub: is there "a traveler" to make the trip once his or her atoms have been torn apart? Objectively, we have a person that's been torn apart right down to the level of atoms; then, those atoms (which are now rearranged into and exist as a beam) are fired through space; then those atoms are reassembled into a material configuration identical to that of the destroyed "traveler", but objectively not the destroyed traveler, because s/he was destroyed before the trip took place (the trip being the teleporting of his or her atoms; objectively, the "traveler" doesn't take the trip, the beam does; "though they said he was beaming upon arrival at StarBase 7" - sorry, bad joke).
If whatever in between happens in a shorter time than it takes for one neuron to signal to another, the process of consciousness stops in one place and continues in another. The same process.
The process of consciousness is not the person though, just a subset of the activities of the local material system we call "the person". The process of consciousness is a description and property of the local material system, not something separate from it that can be abstracted and transferred (according to physicalism, that is; in some ontologies, idealist or spiritual ontologies, it can; but not under physicalism). Destroy the local material system, and all its properties vanish too, necessarily. Creating an identical material system somewhere else one of whose local properties is consciousness of whatever the destroyed material system would have been conscious of the instant after its destruction is just that, creating an identical material... [bla bla bla] ...instant after its destruction: two separate processes occuring in two separate systems. Sure, if you ignore the material destruction and recreation, it might seem like they are one continuous process, when we imagine them as a continuous subjectivity; but that's the Fallacy of Subjective Ontology again; objectively, they are two separate processes, belonging to two separate material systems, which for two separate moments in spacetime happened to be identically configured. That's all.
(In Star Trek travelers are supposedly held in a "stasis field" so that all of the processes in their bodies are halted during the visibly slow transport. I guess the effects department could only use still images for the transporter effects).
Yeah, that "stasis field" is a neat trick; in sci-fi, if you need some magic, just give it a sciency-sounding name and don't sweat the details. That seems to have been the case with the teletransporter. We know it can't work in our universe (5th & last time, promise; see: No-teleportation theorem
WP) unless QM and the uncertainty principle (among other things) is wrong; so what sort of physics does a working transporter entail in the Star Trek Universe, and is it even consistent? (So far, afaics, no.) As a thought experiment, how does it bear on our notions of "consciousness", "identity", etc.? Well, these are extremely subtle and tricky concepts (I'm certainly still doing my best to puzzle them out, and try - despite ego and wanting to be right darnit all the time! - to stay open to conflicting points-of-view which might revise or at least make me think harder about my own; and yours have made me think harder, so thanks); the teletransporter exercise is as good a starting-point as any I've come across for really digging into and discussing them.
