Jesse

elwoodblues:
Correct, and I haven't seen any evidence either. What I ALSO haven't seen is a compelling argument that the brain cannot employ quantum effects in the same way that a theoretical quantum computer could.

The usual answer is decoherence. To have a quantum computer you need all of the elements of the computer to remain in quantum coherence, which is destroyed if the system interacts in even very small ways with the outside world; the larger (and hotter) the system, the more likely it is that small thermal interactions with the outside world will cause decoherence. This is why most attempts to build a quantum computer today involve a small number of particles at close to absolute zero. Although it's not impossible that a way around this will be found (no one would have expected superconductivity at warm temperatures before it was discovered), most physicists think it is very unlikely that large-scale quantum coherence could exist in the brain.

Physicist Max Tegmark wrote a paper on this issue which is often cited, called "The Importance of Quantum Decoherence in Brain Processes"--you can find it on his <a href="http://www.hep.upenn.edu/~max/brain1.html" target="_blank">quantum brain</a> page.

In any case, quantum computers cannot actually do anything that cannot be mimicked by classical computers; it's just that for certain types of computations they are exponentially faster. But if you want quantum effects to make the brain do something radically different than any classical computer, you'll have to postulate new laws of physics as Penrose does.

[ September 24, 2002: Message edited by: Jesse ]</p>

Jesse

marduck:
Interesting idea, what if we replecate you, or State S, into 2 androids, one red and one blue. After the procedure do you awake in the red or blue android? will you care if they scrap the one not of your color? do you awake at all? How will anyone ever know? or is it just two copies holding your memories?

Well, according to the many-worlds interpretation of QM something like this is happening every instant anyway. Although it's a bit weird on first glance, I can't see anything particularly inconsistent about the idea that consciousness can "fork" like a river, so that in your thought-experiment both androids would be true extensions of the original, while from the original's point of view there'd be a 50-50 chance that when he woke up he'd find himself to be the red android or the blue one.

In any case, it can't be the actual atoms which determine who you are; your atoms are constantly being replaced, so you're going through a slow version of a star-trek-style "transporter" every few years. How is replacing the neurons with functionally identical computer chips any different? I guess you could always postulate a nonphysical "soul" to assure continuity of consciousness, but then how does it interact with the brain? Through the pituitary gland, as Descartes suggested?

Anyway, I suspect that these sorts of philosophical questions would become moot if uploading was every actually realized. Imagine a world where uploading is common, and uploads act like they are "the same person" as they were before the procedure; imagine some of your closest friends did it, and you couldn't see any way in which they were changed. Although it would still be logically possible that the original's consciousness was destroyed and a new being with "false memories" was created, it would be hard to take this seriously, in much the same way that it'd be hard for us to take seriously the idea that our consciousness is destroyed every time we go to sleep and a new one is created when we wake up, although logically there is no reason this couldn't be the case.

[ September 24, 2002: Message edited by: Jesse ]</p>

Marduk

"Although it would still be logically possible that the original's consciousness was destroyed and a new being with "false memories" was created, it would be hard to take this seriously"

I still won't do it, no way!! There may come a time when everyone is dead and no one will know. All replaced by identical bodies. I'm thinking "Invasion of the Body Snachers" here!

Jesse

marduck:
I still won't do it, no way!! There may come a time when everyone is dead and no one will know. All replaced by identical bodies. I'm thinking "Invasion of the Body Snachers" here!

Sure, it's logically possible that that's what a society of uploads would "really" be like. But how do you know that your consciousness wasn't created when you woke up this morning and that it won't be destroyed when you go to sleep? How do you know that all people of the opposite sex aren't really "zombies" who act conscious but really aren't? These things are logically possible too, and I see no reason why they are a priori any more or less plausible then the "uploads are zombies" scenario. The reason they seem less plausible is just that we are used to the idea of going to sleep and waking up (or at least we have memories of being used to it--maybe we have only been experiencing those memories for a few hours!), and we are used to interacting with the opposite sex regularly. But in a society where uploading was common, people would have just the same sort of intuitions about uploads. Likewise, a member of an alien race which didn't sleep might have serious suspicions about our own continuity of consciousness, just like your suspicions about uploading. Like I said, there doesn't seem to be any reason why any of these possibilities should be more or less plausible than the others, aside from the fact that we are accustomed to some but not accustomed to others.

[ September 24, 2002: Message edited by: Jesse ]</p>

elwoodblues

Good point! I hadn't thought of that. I'll have to think about it...

Marduk

Because AFAIK sleeping doesn't destroy the original version, there is not two of me crawling out of bed in the morning, an upload would or might.
Either way, just count me out.

Marduk

" How do you know that all people of the opposite sex aren't really "zombies" who act conscious but really aren't?"

This one I'm not so sure about now.

Jesse

marduck:
Because AFAIK sleeping doesn't destroy the original version, there is not two of me crawling out of bed in the morning, an upload would or might.

Sure, but your consciousness is shut down and rebooted...to someone who wasn't used to it that might seem worrisome. If by "original version" you just mean that your brain is made out of the same matter when you go to sleep and when you wake up, what about the long-term replacing of atoms due to eating and drinking? I've heard people say that your atoms are completely replaced every 7 years, I don't know if this is one of those made-up figures or not, but say it's about right--what makes you think your memories of more than 7 years ago really happened to "you"? How is gradual replacement of atoms different from instantaneous replacement a la star trek? What if your neurons were gradually replaced with functionally identical computer chips over a period of many years?

As for the opposite sex being zombies, you joke, but that sort of underscores my point--we're so used to dealing with people of the opposite sex (or of different races, different eye colors, or even anyone who isn't me) that the idea of them being unconscious zombies is impossible to take seriously except as a sort of silly thought-experiment. Now imagine a world where uploading is common, almost everyone has had the experience of someone close to them being uploading, and then of the relationship continuing for years afterwards...I think anyone who seriously entertained the idea that uploads are unconscious would be considered a nut, the same way we think of members of racist cults who entertain similar ideas about nonwhites (such people do exist).

Of course, all this assumes that uploaded people really would act just like the "originals." Maybe they'd all act like lobotomy patients, in which case we'd be a lot more likely to take seriously the idea that there's something about human intelligence which can't be captured on a computer, and that unlike real lobotomy patients those attempted uploads might not be conscious at all.

I think we'll have the answer to this last question within a few decades. All it should take is enough understanding of neurons and neurotransmitters to be able to simulate interactions between individual neurons accurately, the technology to map out an entire brain at the synaptic level, and the computing power to simulate all those neurons on a computer...there'd be no need to know how the brain actually works at a higher level, provided it's some function of the organization of the individual neurons. If you project trends like Moore's law into the future we'll probably have the needed computing power by 2030 or so:



As for increases in brain-scanning technology, there are fewer data points here, but there is also some evidence for an exponential trend:







(charts from <a href="http://www.kurzweilai.net/meme/frame.html?main=/articles/art0134.html" target="_blank">Ray Kurzweil's article</a> on exponential trends in technology)

These charts concern trends in noninvasive brain scans--if you also include the possibility of destructively scanning a dead brain (by freezing it and slicing it into sections, perhaps, as was done with the full body-scan of an executed man who donated his body to science, the details of which can be found <a href="http://www.nlm.nih.gov/research/visible/visible_human.html" target="_blank">here</a>) then uploading might be a lot easier. My guess is the first uploads will be people who specify in their wills that they're willing to give it a try after they die--at that point, what have you got to lose?

The Other Michael

Hi Michael,

I think it was Fred Pohl's "Heechee" series that had a lot of plot dealing with downloaded persons.

However, they were a separate entity from the original person. It was a copying process, not a transfer.

cheers,
Michael

Mr. Sammi

Nanotechnology - no idea.

AI - No confidence in human intelligence, much less robot intelligence..

Immortal Androids - Will never happen.

Interstellar travel - Will never happen. We are alone.


Sammi Na Boodie ()