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Are Physical Laws Inevitable?

math.columbia.edu

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Re: Are Physical Laws Inevitable?

#51

Post by tsimionescu »

raspasov wrote: post #48
tsimionescu wrote: post #42

Earlier quoted context omitted.

> Sure, we might not have a plausible way of testing it today but that doesn't mean there won't be in the future. 2000 years ago people were on the right track that the Earth is round but couldn't "test it" but going around it. I'm sure the prospect of going round the earth back then seemed as distant as testing a multiverse today. But there lies the problem: people 2000 years ago had a very clear idea of how they co…

I am not a physicist, but one can definitely come up with thought experiments about testing the multiverse. One could imagine creating a universe in a lab "from nothing" since there's a hypothesis that the energy of a universe could be zero (see https://en.wikipedia.org/wiki/Zero-energy_universe and https://en.wikipedia.org/wiki/Inflation_(cosmology) ). Now, we might not be 2000 years but perhaps 20,000 or 20 million…

Creating a new universe inside our own would not prove that universes other than our own and the newly created one exist. Sure, it proves that it is possible, but that would not be surprising. The argument is that we have no physical argument that can either prove or disprove the existence of extremely distant other universes, and simply creating one would not move that debate in any direction at all.

This goes even more for the many - worlds interpretation of quantum mechanics.

On the last point, I do agree. I realize how it sounded, but I didn't mean to imply that string theory is as plausible as Aristotle's physics. Still, it is somewhat intellectually dangerous to believe in a theory that does not make testable predictions.

Re: Are Physical Laws Inevitable?

#52

Post by yters »

ithkuil wrote: post #49
yters wrote: post #34

Earlier quoted context omitted.

Doesn't this thought experiment illustrate the absurdity of consciousness cloning? Consciousness cloning is a logical implication of conscious machines. Hence, by modus tollens, machines cannot be conscious.

I thought I set up the thought experiment in such a way to separate the question of whether machines can be conscious from the question whether you'd feel any different if multiple concurrent and non-communicating "yous" would exists, with the purpose of engage in a discussion about Wigner's friend scenario. From your answer it seems you're also ruling out, a priori, the possibility that cloning a conscious being is…

It fundamentally is a category error. A consciousness is inherently unique. If we 'cloned' it, it would be a different consciousness, so it cannot be cloned.

For example, in your scenario, neither of the consciousnesses is ever going to experience what the other experiences. Thus they must be different, and not truly clones.

On the other hand, if I copy a piece of software, it is in some sense the same software in both instances, though their histories are different.

Re: Are Physical Laws Inevitable?

#53

Post by perl4ever »

ithkuil wrote: post #49
yters wrote: post #34

Earlier quoted context omitted.

Doesn't this thought experiment illustrate the absurdity of consciousness cloning? Consciousness cloning is a logical implication of conscious machines. Hence, by modus tollens, machines cannot be conscious.

I thought I set up the thought experiment in such a way to separate the question of whether machines can be conscious from the question whether you'd feel any different if multiple concurrent and non-communicating "yous" would exists, with the purpose of engage in a discussion about Wigner's friend scenario. From your answer it seems you're also ruling out, a priori, the possibility that cloning a conscious being is…

I can't answer for someone else, but I don't think conscious beings can be cloned for the same reason that objects in general can't be cloned. I guess my rudimentary understanding of the uncertainty principle?

Of course, that's different from people being cloned all the time implicitly, aka many-worlds.

However, my instincts also tell me that reproducing quantum states for quantum computing must be basically the same thing as cloning objects, difficulty-wise, so I expect large quantum computers to become exponentially difficult to construct - but smart people who actually understand the math don't seem to believe that. So I don't have firm grounds for knowing the world works the way I think it does.

Re: Are Physical Laws Inevitable?

#54

Post by perl4ever »

tsimionescu wrote: post #51
raspasov wrote: post #48

Earlier quoted context omitted.

I am not a physicist, but one can definitely come up with thought experiments about testing the multiverse. One could imagine creating a universe in a lab "from nothing" since there's a hypothesis that the energy of a universe could be zero (see https://en.wikipedia.org/wiki/Zero-energy_universe and https://en.wikipedia.org/wiki/Inflation_(cosmology) ). Now, we might not be 2000 years but perhaps 20,000 or 20 million…

Creating a new universe inside our own would not prove that universes other than our own and the newly created one exist. Sure, it proves that it is possible, but that would not be surprising. The argument is that we have no physical argument that can either prove or disprove the existence of extremely distant other universes, and simply creating one would not move that debate in any direction at all. This goes even…

"a theory that does not make testable predictions."

When people use this phrase, I think they are often referring to a theory that "does not make testable predictions that are different from the mainstream accepted theory". But I wonder to what extent new science requires looking at familiar things differently first?

Re: Are Physical Laws Inevitable?

#55

Post by dragonwriter »

raspasov wrote: post #36

After reading a few blog posts and interviews with Peter Woit, I think I can say he's definitely a little bit "fringe" as far as physics is concerned. He does try to stick to the science (of sorts) but using some philosophizing he makes critiques like here: https://blogs.scientificamerican.com/cross-check/why-string-... "This is however a straw man argument: the problem with such research programs isn't that of direc…

> 2000 years ago people were on the right track that the Earth is round but couldn't "test it" but going around it.

2,200+ years ago, and while they couldn’t test it by going around it, still, they could test it with a prediction of measurement differences which would be found if it was round and would not be found if it was not, and, as a bonus, whose magnitude would also tell the size of the earth if it was round. Could—and did. The prediction was not untestable, even with the technology of 194 B.C.

Re: Are Physical Laws Inevitable?

#56

Post by dragonwriter »

raspasov wrote: post #48
tsimionescu wrote: post #42

Earlier quoted context omitted.

> Sure, we might not have a plausible way of testing it today but that doesn't mean there won't be in the future. 2000 years ago people were on the right track that the Earth is round but couldn't "test it" but going around it. I'm sure the prospect of going round the earth back then seemed as distant as testing a multiverse today. But there lies the problem: people 2000 years ago had a very clear idea of how they co…

I am not a physicist, but one can definitely come up with thought experiments about testing the multiverse. One could imagine creating a universe in a lab "from nothing" since there's a hypothesis that the energy of a universe could be zero (see https://en.wikipedia.org/wiki/Zero-energy_universe and https://en.wikipedia.org/wiki/Inflation_(cosmology) ). Now, we might not be 2000 years but perhaps 20,000 or 20 million…

> I am not a physicist, but one can definitely come up with thought experiments about testing the multiverse.

No you can't, because it is logically impossible. If you can experience effects that it causes, it isn't a separate universe. To test it, you must observe effects caused by it's existence that would not be expected to be present if it did not exist. Ergo, you cannot test the existence of other universes.

> One could imagine creating a universe in a lab "from nothing" since there's a hypothesis that the energy of a universe could be zero

Sure. But you can't ever observe that you have created it (or, more precisely, you can't ever observe anything that would distinguish what you have created as another universe, only as an object in our universe.)

Not that, even if it were possible to observe, creating universes in the lab would in any way test multiverse-based cosmological speculations.

Re: Are Physical Laws Inevitable?

#58

Post by perl4ever »

ncmncm wrote: post #35
perl4ever wrote: post #27

Earlier quoted context omitted.

Why would a shared past equal a shared future? I mean, you don't treat twins as though they are a single person, right?

Some people do. Dress them the same, even.

I would say treating them the same is an affirmation that they are different people. If they really were the same person, nothing would have to be done twice.

Re: Are Physical Laws Inevitable?

#59

Post by ithkuil »

perl4ever wrote: post #53
ithkuil wrote: post #49

Earlier quoted context omitted.

I thought I set up the thought experiment in such a way to separate the question of whether machines can be conscious from the question whether you'd feel any different if multiple concurrent and non-communicating "yous" would exists, with the purpose of engage in a discussion about Wigner's friend scenario. From your answer it seems you're also ruling out, a priori, the possibility that cloning a conscious being is…

I can't answer for someone else, but I don't think conscious beings can be cloned for the same reason that objects in general can't be cloned. I guess my rudimentary understanding of the uncertainty principle? Of course, that's different from people being cloned all the time implicitly, aka many-worlds. However, my instincts also tell me that reproducing quantum states for quantum computing must be basically the same…

Yeah, being cloned implicitly while in superposition (whether interpreted as many worlds or not) is what I was a was going after in order to address the fact that Wigner's friend situation doesn't have to be absurd.

That doesn't require us to clone an object; the argument only requires us to imagine how would it feel if it's happening all the time to us and conclude that we wouldn't feel a thing subjectively.

Re: Are Physical Laws Inevitable?

#60

Post by ithkuil »

yters wrote: post #52
ithkuil wrote: post #49

Earlier quoted context omitted.

I thought I set up the thought experiment in such a way to separate the question of whether machines can be conscious from the question whether you'd feel any different if multiple concurrent and non-communicating "yous" would exists, with the purpose of engage in a discussion about Wigner's friend scenario. From your answer it seems you're also ruling out, a priori, the possibility that cloning a conscious being is…

It fundamentally is a category error. A consciousness is inherently unique. If we 'cloned' it, it would be a different consciousness, so it cannot be cloned. For example, in your scenario, neither of the consciousnesses is ever going to experience what the other experiences. Thus they must be different, and not truly clones. On the other hand, if I copy a piece of software, it is in some sense the same software in bo…

Sure, each instance of consciousness is independent, regardless of whether it shared history with another consciousness instance, and would feel things independently. I'm glad we're on agreement here.

Apparently we don't mean the same thing by "cloning". Let's call it "forking".

Btw, the same "uniqueness" issue applies to running software as well. The instance of a running software is not the same thing as the code of the software. If you take a snapshot of a software running on machine A and resume it on machine B, they no longer _are_ the same instance. It's clear that they exist independently because you can act on them independently and their state and future reactions will diverge.

That said, it's trivial for us to run n copies of the same state transitions with software (in lock step), something that might just not be possible for us to do with arbitrary precision on biological systems. That's not what I meant by cloning: I'm not saying having an exact "lock-step" reproduction of whatever the internal mechanism of consciousness is (that would be another debate).

But let's get back to the main point of my argument in this thread:

Wigner's friend thought experiment is absurd/paradoxical only if we cling to the notion that we'd somehow be subjectively affected by the fact that nature effectively forks off and entertain parallel histories for complex systems such as conscious beings in the same way as it seems to fork off and entertain parallel histories for simpler quantum systems when they are in superposition state. We don't have to invoke the many-worlds interpretation, which is just an interpretation; we can jus look at the math that describes how quantum states evolve: our most accurate description of what we observe in the world tells us that the behaviour of particles is consistent with viewing them as if they fork off and evolve in parallel over time until, at some point, when we add ourselves in the mix as "observers" then suddenly puff this superposition collapses and we observe the particle having a concrete state, at random.

Common ways to explain this collapse are:

1. The act of observing a system, done by a conscious being, collapses the quantum state, because consciousness is special

2. A conscious being it's just a very complex system that obeys the same rules governing the system it obseves, and thus gets involved in the superposition while performing the measurement, literally becoming part of the superposition. Thus the observed randomness is just an artefact of subjectively "waking up in room 1"

Wigner's setup exaggerates this problem by adding another observer (the scientist friend). It poses absolutely no problems of you espouse the second explaination above. It poses all sorts of problems if you absolutely cannot stomach the possibility that all of us people might not live in a uniform linear objective reality that works according to our intuition.

Simple != Intuitive

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