Imagine a universe which is exactly like our own, except that all three of the following devices could be built. Device number one looks at your body and writes down the position and state of every particle in it instantaneously, or at least so quickly that it seems instantaneous. Device number two kills you, either at the same time as device number one is doing its thing, or at some later stage. Device number three -- which might be located anywhere -- takes the information written down by device number one, and uses it to reconstruct a copy of you which is indistinguishable to an outside observer from the person who was examined by device number one.
(In our universe, devices one and three cannot be built: they violate the uncertainty principle of quantum mechanics. Even if they didn't, the amount of data which would have to be transferred is impossibly big. The human body contains something like 5,400,000,000,000,000,000,000,000,000 atoms; accurately recording the position and velocity of each of these would require -- let's say -- twenty-four bytes of information. A terabyte of data can be stored in hard disks weighing a kilogram or two; storing all this data would require hard disks weighing about as much as the British Isles. By contrast, device number two is easy to build, and throughout recorded history human beings have shown considerable ingenuity in making numerous versions of it. For our purposes, it may as well be completely comical: a man with a shotgun standing outside the booth containing device number one will suffice.)
With devices one, two and three, I can build a teleporter. You walk into a booth and press a button. Device number one records your body, and transmits it to device number three, which is located somewhere else -- let's say Australia. Leaving the booth, device number two does its stuff: a shotgun-wielding maniac blows you away. This is not a neat teleporter; if forced to use it, the crew of the Starship Enterprise would have spent a lot of their time cleaning blood off their decks. But it clearly is a teleporter: to a witness in Australia, the person who steps out of device three is the same as the person who stepped in to device one; and when asked their experiences, they will explain that they walked into a booth in Britain -- ignoring the shotgun-wielding maniac as they passed -- pressed a button, and found themselves in Australia.
But what do you experience when you walk in to device number one and press the button?
To my surprise, this question has generated considerable discussion among people I've asked. (I was also very surprised that there are people who haven't heard this question -- or something very like it -- before.) For those who aren't sure, some further questions:
- Suppose that devices one and three have been supplied by space aliens, and nobody understands how they work. The phone lines to Australia are down, and it's just possible that the whole thing is a practical joke. Device number one is a Great Big Lie -- it's just a phone booth with a button in it -- and device number three doesn't exist at all. What do you experience when you walk into the booth and press the button? If no-one can tell the difference between the real and fake devices, would your experience of the fake device differ from your experience of the real one?
- If the question, `what do you experience?' seems ambiguous, can you rephrase it as, `at the moment that you press the button in the booth, what would you believe would happen next?'
- Suppose that devices one and three work as described, but the internet connection to Australia is very slow. It will take a week for all the information read by device one to reach device three. Suppose further that the shotgun-wielding maniac is having an off day, and he merely clips you; you manage to escape before he can reload. A week after pressing the button in the booth, you are recovering in hospital; in Australia, a copy of you is made in device number three. What do you experience?
- Suppose that, rather than in Australia, device number three is actually located at the bottom of the deep ocean. The person who materialises in device three immediately drowns. Does this make any difference to your experience? What if device three is in the space aliens' secret (oxygen-filled) base on the Moon? What if it's on a planet orbiting Alpha Centauri?
- Would you use such a machine? And if, rather than a shotgun-wielding maniac, device number two were replaced with some means of killing which was guaranteed to be painless and instant?
- (If applicable.) What happens to your soul?
If you want to know what I think, read this; but make up your own mind before you do. At this point I should also apologise for inverting the purpose of this web log; I've already bored people in the pub with this question, but every time it comes up in real-life conversation an argument starts, so I may as well get some web log mileage out of it. Also, a special request for the comments: I'm not a great fan of brand-name philosophy, so if you feel it's necessary to invoke a brand-name philosopher to explain your answer, then please either (a) reconsider and phrase your point in English; or (b) post a holiday photograph to compensate, as with my ID cards strange attractor. And, again, sorry: no graph (next week...). At least this piece isn't about ID cards, though please do come to Mistaken Identity on Wednesday, especially if you're David Blunkett.
Comments
Posted by Roy Badami, Saturday, 15 May 2004 12:31 (link):
What happens to your soul?
The soul is clearly a quantum mechanical phenomenon. In the universe you postulate, we would not have souls... :-)
-roy
Posted by Roy Badami, Saturday, 15 May 2004 12:35 (link):
Or alternatively, consciousnous is a quantum mechanical phenomenon.
So when you walk into the booth and press the button, you would experience precicely nothing because, in that universe, you wouldn't be capable of exeriencing anything.
Posted by Chris Lightfoot, Sunday, 16 May 2004 10:57 (link):
This is a cop-out too, but it's quite a good cop-out, because it does short-circuit the whole argument in a way that I rather like....
Posted by Roy Badami, Sunday, 16 May 2004 23:25 (link):
On a slightly related note: I'm actually very wary of any thought experiment that contains a premise that is impossible.
I'm reminded of the thought experiments that create contradictions by considering the behaviour of a perfectly rigid body travelling at relativistic speeds as seen by observers in different frames. The resolution is of course that the laws of physics forbid perfectly rigid bodies. The nature of the universe is such that if you start from an impossible premise, you may well reach non-sensical conclusions...
Incidentally, your linked explanation of your view of this contains the premise that a future event (the failure of the information stream between processes 1 and 3) cannot influence your experience during of process 2.
This is by no means axiomatic. Consider the Bell's inequality experiment. Notwithstanding the dispute about the particular experimental results, it would appear that quantum non-locality is a concept that at least some physicists are willing to entertain. Which, as I understand it, has the consequence that an event can sometimes influence events outside its light cone, as long as it does so in a way which doesn't allow information to be conveyed outside that event's light cone.
So the successful application (or otherwise) of process 3 could conceivably influence what you experience during processes 1 and 2, as long as it doesn't change your behaviour as observed by others (if it changed your observed behaviour, then someone would be able to send a message outside their light cone by sabotaging process 3). Since the first you is dead after process 2, I don't think this would create any paradoxes.
FWIW, my inclination is to answer the question the same way you do (with the proviso I give above that I'm disinclined to answer the question at all :-)
Here's another scenario that amuses me. Consider that the whole system is supplied by aliens, and that processes 1 and 2 are integrated in a single unit. The aliens simply tell us that it's a teleporter, and we know nothing about how it works. They may or may not counsel against its use for transporting humans, but let's say we do it anyway.
When you press the button, you'd either experience a painful death, or perhaps just painlessly cease to experience anything more. However, there would of course be no evidence for this. In fact, there'd be considerable evidence to the contrary, since if people questioned you after you'd been through the teleporter, the experience you'd describe would be pressing the button and then finding yourself in a different place.
I therefore resolve never to use a teleporter supplied by aliens without first understanding how it works, even if there is a body of circumstantial evidence that its use is perfectly safe. Given how bad I am at keeping resolutions, I fully expect to break this one sooner or later, though :-)
-roy
Posted by Julian T. J. Midgley, Monday, 17 May 2004 07:56 (link):
It's amusing, but since it depends on the entirely unproven hypothesis that consciousness is an artifact of quantum-mechanical processes, it isn't especially enlightening. Consciousness could as well (and, in my opinion, is rather more likely to be) the consequence of chaotic effects well above the quantum level. Neurons and synapses are so much larger than the scale at which quantum effects become significant that it seems improbable that quantum mechanics has much sway over consciousness.
Posted by Roy Badami, Tuesday, 18 May 2004 22:47 (link):
I'll buy that. Though it appears that (like me) you quite like the idea that consciousness relies on a system that doesn't behave in an obviously deterministic manner...
It may or may not be of any interest to observe that quantum mechanics causes chaotic systems to become genuinely non-deterministic in the real world, whereas in a Newtonian universe they would still be deterministic if you knew the state to arbitrary precision.
-roy
Posted by Francis Irving, Sunday, 16 May 2004 03:43 (link):
OK, I think Chris is wrong. To summarise, I think he's wrong because he doesn't fully understand the nature of time and self. Not that I truly feel that nature to the depths of my being, but I can give some rational arguments about it.
I'm assuming for this discussion that the universe is materialistic, and that we have no special soul. In other words, we are merely an aggregation of particles which behaves in a complex manner. Some questions to ask about your consciousness in this universe:
* How do you know that if you stay where you are now in the same place, you will experience consciousness in a moments time in the same place?
* If you move slightly across the room, how do you know that your consciousness when you have moved is the same person as now?
All you have to go on is memory. You remember that last time you did it, you believed that your consciousness moved with you. But that is just memory of memory. All you are is memory of memory taking decisions. Even the memory takes time to happen, you don't really exist at one instance in time (their are interesting experiments about our time perception, which show that consciousness happens after decision making).
For practical purposes we believe that our consciousness is a stream, passing forwards through time. But really there is no such thing as self (nor such a thing as no-self, that would be just as stupid a belief). There is some stuff which does things and leads to some more stuff. The stuff is particularly complex, and self-reflective, and for practical reasons creates a story of itself as a continuous being, recalling its previous positions and activity in the universe for the purposes of making future decisions.
Moreover, there is no such thing as progression of time. Yes, the universe has rules to do with time encoded in its laws. But we only experience time in the sense that we only have memory backwards, and there is a certain direction of cause and effect.
So what do you experience when you press button 1? That's a meaningless question. There is no "you" for that question to answer. Take this universe as a 4 dimensional (say, this may as well be Newtonian since we removed quantum mechanics already) static object - 3 dimensions of space, 1 of time. In that case there is a me now, sitting here typing on this computer. There is also a roughly similar entity there a fraction of second later, who given the laws of causality will experience that he has passed continuously from the one moment in time to the next.
Likewise, there is me about to press the button in Chris's "teleportation" machine. And I press the button. Then, a moment later there is a me in roughly the same place with a continuous memory. Likewise there is a me in Australia next week with a continuous memory. When you consider the universe as a static object, there really is no difference between these two entities.
So I hear you cry -- again! -- what do you experience? Well you don't. One doesn't experience forwards in time, one experiences backwards. So it's just a gibberish question. You can't ask what you will experience next. You can, as Chris says, ask what you /believe/ you will experience next, but that wouldn't be a very interesting thing to ask -- it wouldn't alter the fact that you only experience backwards, and the question is moot.
So there will be two yous, both conscious, both existing in the same universe, who both experience backwards in time that they just pressed the teleporter button. If you are still asking the question "which do you experience", then you need to think harder about what you mean by "you". And you need to consider what you currently believe to be a forwards stream of consciousness in a more critical light.
Posted by Chris Lightfoot, Sunday, 16 May 2004 10:56 (link):
That's a cop-out. You frequently answer questions which aren't very interesting. Do you think that you would have a firm belief at the time you press the button? What do you think it would be?
Posted by Francis Irving, Sunday, 16 May 2004 12:26 (link):
Are you saying that if I firmly believed I was going to be in Australia, then that is where I would experience myself being?
Posted by Chris Lightfoot, Sunday, 16 May 2004 12:31 (link):
If so, I want some of what you're smoking.
Let me put it another way. Asked at the moment of pressing the button, would you think that you will believe something different will happen to you in the fake machine than in the real one?
Posted by Francis Irving, Monday, 17 May 2004 00:23 (link):
In the fake machine I am confident that I would experience myself being in the same place. I have a philosophical suspicion that this is a misgrounded confidence, but no more so than the similar belief I have as I sit here and type this.
In the real machine I would not know what to believe I would experience. I would be very curious (and frightened) of what was going to happen.
And, yes, I am saying that an appearance of molecules ordered just like me remote in time and space can affect my experience. Of course it can, it happens all the time, just over much smaller distances as I walk across a room.
Posted by Chris Lightfoot, Monday, 17 May 2004 01:27 (link):
Posted by Francis Irving, Tuesday, 18 May 2004 06:05 (link):
1. If I didn't know whether the machine was real or not, then I wouldn't know what was going to happen to me. Not sure quite what you're getting at with the question. I would have a conditional belief: "If the machine is fake, then I'll definitely walk out of here and get shot. If the machine is real, I don't know what will happen to me."
2. No. I assume you mean my "walking across the room" example as a continuous displacement example? I, and I believe you, have no evidence that "continuous movement" is necessary to preserve some kind of "forwards stream of consciousness". What evidence do you have that that is the case? What evidence do you have that "walking across the room" is a continuous movement in any sense? We have no idea if the (even Newtonian) universe if continuous or discrete at the bottom. And even if we did, we have no evidence that consciousness depends on things moving continuously.
Posted by Chris Lightfoot, Tuesday, 18 May 2004 17:39 (link):
Even if there were no test whatever which could be applied to tell you whether the machine was fake or real?
Necessary but not sufficient. I'm claiming that discontinuous movement is likely to be bad for you, as in, for instance, a car crash.
Posted by Peter Clay, Tuesday, 25 May 2004 15:37 (link):
If that's the case, then 'fake' and 'real' have no empirical meaning. Stepping into the machine and pressing the button is clearly a test of whether it's real or not, depending on whether machine 3 does its job. After someone's done that, you know whether it's a real teleporter or not.
Somehow this reminds me of a William Gibson short story in the Burning Chrome collection, where there is a large collection of alien ships that have been found, with pre-programmed FTL drives. People climb into them and press the buttons. They disappear; some time later they come back. Well, some of them come back. Some of them come back with nothing. Some of them come back with amazing artefacts. Some come back dead. Quite a lot of them come back deranged or suicidal. Despite all this, there is a huge waiting list for the opportunity to try this.
(Ooh, I note you've only allowed logical markup in comments. Cool.)
Posted by Roy Badami, Sunday, 16 May 2004 23:34 (link):
Incidentally, I think the difference between your (and my) position and Francis's position stems from a philosophical difference about the nature of consciousness.
-roy
Posted by Francis Irving, Monday, 17 May 2004 00:24 (link):
Could you elaborate what you think the philosophical difference actually is?
Posted by Julian T. J. Midgley, Monday, 17 May 2004 09:42 (link):
So, Chris is 'clearly' wrong...
His argument is that since "we cannot distinguish" a fake transporter from a real one, then what we experience in the fake one must be the same as that which we would experience in the real one. To persist in the overuse of a word that is self-evidently inappropriate given the debate this topic has created - this is clearly fallacious.
Firstly, how would I answer the question - well I believe I would become two 'me's and so would experience both being shot and finding myself in Australia, and if such teleporters were to be become a routine means of travel, I would rapidly start ignoring the "being shot" bit (because I would have been through hundreds of teleporters, without experiencing being shot once (all the 'me's that experienced that died immediately, so my consciousness would have accumulated no memories of it)).
Why is Chris wrong? It's evident that we can distinguish a fake transporter from a real one, just as we can distinguish a car journey in which die in a fatal accident from one in which we do not. If, after having been through the "transporter", we have a memory of having been in place A a moment ago, but now discover that we are in place B, then we can say that the transporter is real. If we find ourselves bleeding to death from a shotgun wound, we cannot say whether it was fake or not (since we don't know what happened in Australia). In the case of a real transporter, we will evidently experience both being transported, and being shot (I don't see why this is in the least surprising - there are two copies of 'me', so clearly 'I' can experience two different things simultaneously), but the fact that one of us experiences being transported is sufficient for that one of us to deduce that the transporter is real. The other one never knows whether it was real or not.
It is scarcely surprising that Chris comes to the conclusion that we experience only being shot, since he completely ignores what the copy of us in Australia experiences, yet provides no justification for doing so.
"What do you experience next?" is a question normally taking the answer "I experience...", but in this case it can only correctly take the answer "we experience...". There is no means of deciding which (alone) of the two beings that exist after the copying devices have done their work deserves to be seen as the continuation of the one that entered it, since the only difference between them is that one is in a different place.
Some supplementary questions that should clarify this:
Consider a machine that worked as follows. You walk into a room with two beds and lie down on one. You press a button and are put under general anaesthetic. A copying device instantaneously makes a copy of you on the bed next to yours. The beds are taken out of the room and placed in a different room that you've never seen before, and arranged head to head, where they were previously side by side. You are both revived. What do you experience? What if the two beds are shuffled so that no one knows which was the copy, and then placed in different rooms, one room painted red, the other blue? What if ten copies of you are made, but the original killed while still under general anaesthetic?
Imagine there was a 50/50 chance of a copy of being made of you in your sleep, the original killed, and the copy put back in your bed. How would you know whether you were the original or a copy in the morning? If you are unable to work out which you are, then why is the experience of the Australian copy of yourself in the original question irrelevant as Chris suggests it is?
And finally, suppose someone manages to code a conscious AI in C (this is perhaps more probable than the Uncertainty Principle's turning out to be false). We take their code, and insert the following:
if (lifetime > 10 YEARS) {
if (fork() == 0) {
exit(0);
}
}
What does the AI experience? What would it experience if we commented out the exit()? What if we made it fork ten copies of itself, and none of them exit()ed? What if we dump the memory of the computer it is running on to disk and make some back up copies, then restore these on several different (but identically specced) machines. Can we (or the AI itself) usefully distinguish the original from any of the copies?
To me, it seems quite obvious that if there are numerous conscious entities, descended from a 'parent' by any lossless copying or forking process, then one cannot choose any particular one of them as more deserving of being called the continuation of the 'parent'; a question about what the parent entity believes it will experience as a result of forking cannot be therefore be answered except by reference to the anticipated future experiences of all of the copies (and itself).
Posted by Chris Lightfoot, Monday, 17 May 2004 10:39 (link):
I agree with you in the case where you're copied in your sleep or when unconscious, but that's because there's no continuity of experience between going to sleep and waking up. But I don't agree that the fake teleporter is necessarily distinguishable from the real one. That is, I claim that some third party -- space aliens, perhaps -- can construct a device for which the question, `is this a teleporter?' cannot be answered by any test that we can devise. As another approach to that problem, what do you think about the case where the data get delayed (or lost) between here and Australia? Do you believe that that changes your experience of the device?
I agree with this (and indeed it's in the premises to the question).
But this is just an assertion which you haven't really justified.
(BTW, you meant _exit(0) in your C -- i.e. the system call not the ISO C library call -- otherwise your AI's standard input/output/error streams would probably get shut down in the parent and the child, which would really confuse things....)
Posted by Julian T. J. Midgley, Monday, 17 May 2004 12:25 (link):
What is the meaning of "continuity of experience"? It seems to me that the copy of me that ends up in Australia wouldn't complain of any loss or break in his continuity of experience. He wouldn't report a black-out or anything similar. He would report having walked into a kiosk, pressed a button, and walked out on to Bondi Beach. He would have experienced no more of a break in the continuity of his consciousness than you would if I put you in a room with your field of vision filled by a wall on which was projected the image of a mountain scene and I instantaneously changed the projection to one of the centre of New York City. An AI similarly would report no loss of continuity in conscioussness if you dumped memory to disk and restored it ten years later. It might later deduce that there had been one, but it would find it difficult to determine when precisely it had occurred if one were careful to keep its immediate environment constant before and after the backup and restore operation.
As regards the space alien's device: I really don't see what the trouble is here - what you experience is determined entirely and absolutely by whether the device is a teleporter or it isn't. If it isn't, then you experience being killed. If it is, then you experience both being killed, and turning up at the destination (in different incarnations). What you experience is not in the least dependent on what you know about the device before you press the button. Your answer to the question "what will you experience" is merely a question about your beliefs concerning the device. If you believe that it is a teleporter, you will answer "death and teleportation", if you believe it isn't, "death", and if you're not sure, you'll presumably answer "either death and teleportation, or just death, depending". What you actually experience depends not on your beliefs, but on what the device actually does, and if the aliens are the only ones to know that, then they too will be the only ones to be able to answer the question correctly in advance.
In the case where the data gets delayed on its way to Australia, then again, the Australian copy of me won't notice a break in his consciousness. If he's alert, he may observe that he arrived later than he was expecting to, but the answer to the original question remains "I will experience being shot, and turning up in Australia, independently". If the data is lost, then no one gets to experience turning up in Australia, so clearly the only experience is one of being shot. But that doesn't in any way change the experience of someone whose data doesn't get lost, and I don't yet understand why anyone would think that it might.
Out of interest, does your answer change if the reading device physically pulls you apart atom by atom, sends the atoms to Australia with intructions for putting them back together again, and also uses the instructions to build a second copy of you that it puts back in the kiosk where you started. (I.e. the original physical you gets sent to Australia, and the new copy is the one that walks out and gets shot). Is there any way for a user of the teleporter to tell after the event whether the teleporter works according to your original method, or my revised one? If there isn't, then the experiences of both copy and original are surely equally valid "experiences" as answers to the original question.
I am still not sure what your justification is for ignoring outright the experience of the copy of you that ends up in Australia.
My justification for the statement that one must take account of the anticipated experiences of both copy and original is straightforward - if the copy and original cannot distinguish themselves one from the other, then both their experiences are valid and must be considered. If there is a meaningful distinction between the two, then it may be possible to ignore the experience of one of them- I haven't yet seen anyone draw that meaningful distinction, and I cannot think of one myself.
Posted by Chris Lightfoot, Monday, 17 May 2004 16:34 (link):
I can't see any reason to believe that my `consciousness' would cross 12,000 miles to Australia, simply because device 3 has done its stuff.
Posted by Julian T. J. Midgley, Monday, 17 May 2004 18:49 (link):
So what happens to your consciousness if the device tears your body apart and reassembles it in Australia? Or, to put it another way, with your original 3 devices, how is the consciousness associated with your body in England different from that associated with your body in Australia? In what way is the latter any less 'you'?
Posted by Chris Lightfoot, Monday, 17 May 2004 18:58 (link):
Ah, yes, I forgot to answer that bit. And I'm tempted not to answer it now, because I'm fairly sure that it doesn't meet the original premise of the question (because I don't think that the fact that devices 1 and 3 are possible in the thought-experiment universe necessarily implies that your device could be built there too).
But -- and noting that this is just my interpretation of your description of the device, and I don't believe that this is relevant to the original question -- if the device is `pulling [me] apart atom by atom', I would experience an unpleasant death as my atoms are removed one by one and stuffed down the pipe. The copy in Australia wouldn't have that entire experience (though they might have part of it, depending on the stage at which the configuration of my brain was recorded). The local copy has the same memories as the copy in Australia.
Posted by Francis Irving, Monday, 17 May 2004 15:50 (link):
OK, in that case there is an even better example, which is equivalent to Julians but in which you never fall unconscious. Imagine the top of a lift shaft, you walk in. The lift goes down, then spins round on its axis a large number of unpredictable times. You are a bit dizzy, but there is no way you can tell which direction the exit door is facing.
The lift then opens at the bottom in an underground complex. There is a 50% chance it opens with the door pointing to one room, and a 50% chance it opens with the door pointing to another identical rotationally-symmetric room. The two rooms are indistinguishable to you. Further, nobody except the random number generator in the lift mechanism knows which set of rooms you are going into. You go into the room, and the lift door seals behind you.
You press the button.
You and your (rotated by 180 degrees) copy in the other room then walk out of an exit door on the far side of the rooms you are respectively in. You go outside, then walk round to meet each other. Nobody knows which is the original and which is the copy. You were both conscious all the time. You both experienced exactly the same thing, until the point at which you exited the complex in a different place - and even gives no clue as you were randomly spun about earlier, and don't know where you should have ended up.
Notice that this thought experiment works with your devices 1, 2 and 3 as originally stated by Chris.
So, Chris... Before you press the button, what would you believe is going to happen to you? Which exit do you think you are going to walk out of? And why do you believe this case is any different from the one where one copy is in Australia?
Posted by Chris Lightfoot, Monday, 17 May 2004 16:40 (link):
You've constructed a situation where I will be confused between the two. That's because both copies survive and are placed in identical environments. This is quite different from the situation I posit, where a copy is made and the original killed. Now, if you kill one of the copies at random at the end, then I would judge there was a probability of one half that I wind up being shot when I press the button. (This is the same as the randomly-spinning lift without the copying process, of course.)
As another thought-experiment, if you place devices 2 in Australia rather than here, and kill the copy that's made in Australia, my experience of the machine is that I walk in, press the button, and leave it exactly as I entered it. Over in Australia, a copy of me is made and then shot, which is sad -- but understandably I'm wouldn't be as upset about this as I would be if I were shot.
Posted by Francis Irving, Tuesday, 18 May 2004 06:15 (link):
OK. Suppose that in my rotationally symmetric room example, the computer remembers which one is the original and which is the copy. As they leave the complex, the two beings are stamped with a label A or B, and only the computer knows which label corresonds to the "copy" and which to the "original". The two beings go and live their lives for one week, talk to each other, get to know each other etc. Then some secretary of state or other comes up to them, says "you are the copy!" to one of them and shoots them.
Now, before you press the button, what would you believe you are going to experience?
I'm assuming your answer will be that you are confident you would be the one who isn't shot. In which case, what did you mean when you said to Julian "I agree with you in the case where you're copied in your sleep or when unconscious, but that's because there's no continuity of experience between going to sleep and waking up".
Posted by Chris Lightfoot, Tuesday, 18 May 2004 09:48 (link):
If the copy is the one that's shot, then I walk in to the machine, walk out (slightly dizzy) and emerge to live a natural life (or at least until I fall foul of some other such experiment -- I won't say it's bonkers, but others might). I'm not sure what the point of the question is. The difference is that in the rotationally symmetric room example there is continuity of experience. When you go to sleep there isn't.
Posted by Pete Stevens, Monday, 17 May 2004 09:47 (link):
[to bring this back onto tradition for this weblog]
Clearly Mr Excutioner is going to sell your biometric ID to the highest bidder and the Australian government will imprison you for being a fake, just after your bank account has been emptied. Someone tells Mr Blunkett his ID scheme is broken so he hush hushes the whole thing and gives another five billion of tax payers money to a computer consultancy in exchange for some ROT 13 encryption somewhere in the system.
Posted by Pete Stevens, Monday, 17 May 2004 09:51 (link):
Oh, you also discover that since the momentum of your particles is unchanged, you're now travelling sideways at around two thousand miles per hour which is going to make a mess of the nearest building you're about to hit.
Posted by Chris Lightfoot, Monday, 17 May 2004 10:40 (link):
Later on I was going to introduce the version where device number 2 is in Australia, rather than here, to see whether people would make a different decision about whether to use it. But as Pete points out, this wouldn't be strictly necessary if machines 1 and 3 work as I described....
Posted by Francis Irving, Tuesday, 18 May 2004 06:28 (link):
For the record, it would certainly make a lot of difference to me. If I had any suspicion that the machine was fake, then I'd be much happier to use the one where the aliens claim "copy in Australia gets shot". And I think I would always have some suspicion that the machine is fake.
If it is a real machine, I don't know what is going to happen to "me" with any confidence when there are two of me. My suspicion is that it is a meaningless question to ask, and it is a flaw in my brain assuming one flow of consciousness that leads me to think it is I any way a reasonable question. But psychologically, I'd still have that doubt. So in that limited sense, I'd prefer the machine where the person in Australia gets shot.
However, I'd also think it possible that "I" would next experience being in Australia and being shot, so I still wouldn't like to use the machine. Whereas Chris would happily, and somewhat stupidly, use it. Entirely on the bizarre basis that consciousness flows to things that happen to be spatially located in roughly the same place as they were at a previous instant of time, rather than that consciousness flows with information and cause/effect. Clearly in this case the copy of Chris who appeared in Australia and was shot would somewhat deserve the punishment for his philosophical confidence.
A somewhat severe punishment, I agree, but at least he kept a backup copy in England ;)
Posted by Chris Lightfoot, Tuesday, 18 May 2004 17:45 (link):
If you're going to bring cause and effect into it, then let's try to make your theory causal. What happens if I am never alive in the light cone of the copy? If I am shot before a time of 2d/c + t after pressing the button has elapsed (where d is the distance to Australia and t is any other delay before device 3 constructs a copy), do you think that my experience differs from that described in your 50/50 theory?
Posted by Tom Lynn, Tuesday, 18 May 2004 19:14 (link):
The final words of the one in Australia are presumably: "What? But there's been some misunderstanding! I'm meeeeeeeee..."
Incidentally, Francis, despite mainly agreeing, we differ on best strategy. I optimize for keeping as many mes alive as possible, rather than minimizing my deaths, so I'd go in the machine as many times as possible until I died (or had assembled a big enough army to TAKE OVER THE WORLD).
Posted by Chris Lightfoot, Tuesday, 18 May 2004 19:44 (link):
Tom wrote:
Now I'm worried.Posted by Tom Lynn, Wednesday, 19 May 2004 09:58 (link):
This of course presumes that I believe the probability of there being more than one clone-writing machine is greater than the probability of there being zero.
Posted by Tom Lynn, Tuesday, 18 May 2004 19:08 (link):
...but that won't work! ROT13 looks normal in Australia.
Posted by Pete Stevens, Wednesday, 19 May 2004 10:33 (link):
A large software consultancy using bollocks encryption in an inappropriate fashion. I can see why your skecptical, I can't think of a case where it's happened before.
PS - the secret password almost certainly won't be 'OpenSSH Programmers are Weenies!'
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