I Are the implications of MWI really this horrifying?

[PeterDonis]

How does the fact that probability amplitudes lose coherence lead to the suggestion that they land in... other unobservable universes?

"Lead to the suggestion" is incorrect. The correct statement is that decoherence is the same thing as "landing in other unobservable universes". Decoherence of different branches of the wave function is what defines the different "worlds" in the MWI.

 

[PeterDonis]

Seriously, you need to read up a bit on the MWI, rather than react with astonishment or consternation at every turn this thread takes!

@CoolMint, this is excellent advice for you to take.

 

[Fra]

MWI has no observable consequences beyond the standard consequences of quantum mechanics. Hence there is nothing horrifying to worry about.

Maybe one possible consequence is that thinking too much about it, may give you weird ideas that may not add explanatory yet occupy your attention for better use,

I never got what is attractive, or the promise of MWI. I can't even related to it conceptually in a constructive way, so I rarely butt into MWI threds, this was an exception. The idea that the world splits, but the observer is only in one of them, which problems does it even solve?

/Fredrik

 

[CoolMint]

@CoolMint, this is excellent advice for you to take.

I have. Thanks anyway.

It strikes me that most other interpretations keep shy of making outlandish unverifiable claims.
The mathematical framework doesn't say or hint that there are other parallel universes. I guess I am a disbeliever. I will stop posting to this thread for parsimony reasons - I must have created a billion new universes just by participating in this thread and the resultant interactions.

 

[hungrybear]

No. One "branch" of the wave function will only include the plane crashing if some event with quantum uncertainty has a nonzero probability of making the plane crash. MWI proponents often wave their hands and assume that every event you can possibly imagine has some nonzero probability, but that is not at all obvious when you actually look at the math.

Thanks for both your thoughtful replies Peter. On the above point, isn't it the case that all classical interactions rely on quantum interactions, it's just that some quantum outcomes are extremely statically unlikely? So if every series of quantum outcomes occurs with 100% probability in MWI, it would lead to most conceivable scenarios? This seems like what David Deutsch is talking about when he says most worlds imagined by science fiction exist.

 

[PeroK]

Summary:: The implications of MWI theory seem to me to be horrifying for each us individually. Am I getting something wrong?

It means that with 100% certainty each of us sitting here reading this forum will experience the most distressing and painful possible outcomes. Yes it will be split parts of us but it seems we must think of these split selves as us or the alternative is that we cease to exist and new copies of us are created, which also isn't great.

I really genuinely appreciate any help with understanding this as it scares the hell out of me to be honest.

Let's assume that MWI is not right and there is only one planet Earth in any meaningful sense. Now, let's look at the history of human beings from 1900, say - at least according to mainstream historical record. Assume we can assess everyone's life and make some overall judgement on how good or bad or terrible people's lives have been. A certain number of people - perhaps more than anyone would like to admit - have come to some truly horrific end.

Very optimistically, perhaps, and very simplistically, we are going to say that things are 99% good and 1% bad here on Earth. For example, according to the UN 25,000 people die from hunger every day. That's nine million people every year.

https://en.wikipedia.org/wiki/Starvation

Now, let's assume that MWI is correct. Note that in general, the vast majority of "worlds" have no planet Earth at all; and, the vast majority of those don't have you in it. But, let's focus on the ones that, say, start from the day you were born.

Statistically, most worlds will follow a similar pattern to the one we are familiar with. In fact, the variations (although QM in origin) could be understood by looking at the probabilities associated with higher-level processes; namely, social, political and religious movements that determine, for example, how many wars there are and how many human beings starve to death, or are tortured to death by other human beings.

We have, therefore, a core set of branches or worlds that must look very like our world. They may represent a proportion extremely close to the total number. Overall, therefore, we are still talking about a 99% good and 1% bad experience for a very large (perhaps infinite) number of sub-systems that can be identified as a human being in some way. Even if the suffering is nominally spread out a bit.

The extra branches, therefore, don't necessarily change the overall proportion of suffering against a good life - they may simply multiply everything up. MWI in that respect is no worse or better than the non-MWI single world. It's just more of the same. On average, 25,000 people will be starving to death every day in each of these branches. In a few, perhaps, hunger will have been eradicated; in others, inequality will be much worse than it is in our world.

The rest of the worlds - the ones with the really weird stuff - will be statistically dominated by the more normal worlds.

I would, therefore, refer back to my original point: the horrors of MWI are the same horrors that are already with us.

 

[PeterDonis]

isn't it the case that all classical interactions rely on quantum interactions

That's the current belief, yes. However, we don't have a theory of quantum gravity, so there is one interaction, gravity, that we don't have a theory with which to back this belief up. For the other three fundamental interactions (strong, weak, electromagnetic), we do have such a theory, the Standard Model of particle physics, which is a quantum field theory that includes all three of those interactions.

it's just that some quantum outcomes are extremely statically unlikely?

Yes.

if every series of quantum outcomes occurs with 100% probability in MWI, it would lead to most conceivable scenarios?

Not necessarily, because "conceivable" is not the same as "has a nonzero probability amplitude in the wave function". MWI proponents often talk as though those two things are the same, but they're not.

 

[hungrybear]

The extra branches, therefore, don't necessarily change the overall proportion of suffering against a good life - they may simply multiply everything up. MWI in that respect is no worse or better than the non-MWI single world. It's just more of the same. On average, 25,000 people will be starving to death every day in each of these branches. In a few, perhaps, hunger will have been eradicated; in others, inequality will be much worse than it is in our world.

The rest of the worlds - the ones with the really weird stuff - will be statistically dominated by the more normal worlds.

I would, therefore, refer back to my original point: the horrors of MWI are the same horrors that are already with us.

Yes I guess my meaning is less altruistic than that! The overall proportion of suffering in the world won't change, but what I wonder is, if MWI is true, will I personally suffer all the terrible possibilities I'd be statistically unlikely to suffer if there is just one world? If the particles that make up me in this present moment split into many different worlds in which all possibilities are realized, from the perspective of me in the present moment, the future looks pretty terrifying.

That's why I use the flight example. In a single universe view my chances of being in a plane crash are about 1 in 10,000,000. If I split into all possible futures, the possibility seems to be about 100% certain. The Quantum Suicide experiment suggests a future in which you can expect to survive a quantum suicide attempt – leaving aside the problems with this thought experiment, MWI also seems to imply you can expect a future in which you will always experience the worst possible suffering, among other outcomes.

Let me try to explain my main question in two scenarios:

Someone in a lab measures the spin on an electron

Does MWI mean:

1. There was one version of me, but the experiment literally causes the particles that make up me (and the rest of the world) to split into two, one version of me would go on to learn that the electron was spin up, one would find out it is spin down.

2. There have always been two versions of me who have been experiencing the same things until this experiment. After the experiment one will go on to learn that the electron was spin up, and one will find out it is spin down. The particles making up the different versions of me do not literally split, they just take different routes to different futures.

These two scenarios are very philosophically different, because in version two I can only ever experience one timeline, but in version one, I am continually literally splitting and experiencing every possible future. If the first version is true, philosophy has a lot of work to do on what MWI means for individuals. The second one doesn’t have any huge consequences other being interesting for the imagination.

(Genuinely hope I’m not annoying the hell out of everyone , I just want to understand more and I don’t have the technical ability to follow the literature on this – I also think some of the literature is quite philosophically confused!).

 

[PeterDonis]

1. There was one version of me, but the experiment literally causes the particles that make up me (and the rest of the world) to split into two

This is false. Unitary evolution can't do this.

2. There have always been two versions of me who have been experiencing the same things until this experiment. After the experiment one will go on to learn that the electron was spin up, and one will find out it is spin down.

This is closer to what MWI says.

 

[PeroK]

Yes I guess my meaning is less altruistic than that! The overall proportion of suffering in the world won't change, but what I wonder is, if MWI is true, will I personally suffer all the terrible possibilities I'd be statistically unlikely to suffer if there is just one world?

Yes, I guess, some sub-system that is recognisable as you in some sense will suffer everything with the appropriate probability or weighting. It's not entirely clear how MWI translates into anything meaningful in terms of human experience.

 

[akvadrako]

These two scenarios are very philosophically different, because in version two I can only ever experience one timeline, but in version one, I am continually literally splitting and experiencing every possible future. If the first version is true, philosophy has a lot of work to do on what MWI means for individuals. The second one doesn’t have any huge consequences other being interesting for the imagination.

I don't think they are philosophically different, at least in terms of what you should expect to experience.

Each version of you will only experience one timeline in both the splitting and the diverging descriptions. If this wasn't true, you would already be experiencing something different. So it's a matter of degree how altruistic it is to care about those other "yous" vs other people in the current world, because once the split has happened, you are different beings.

It's hard to explain this in normal language, but there is a classical analogy which I think captures the essence of it pretty well. Imagine we had perfect cloning machines. Each night you enter the machine, the original body is removed, and say a million perfect copies wake up in different rooms which will never interact until the end of the universe. Most of those copies are giving a very typical room, some are given bad rooms, and some good rooms.

From then on they live their own lives – they are not the same person. So even though there is no randomness involved from an objective (god or bird's eye) viewpoint, there is something like a random expectation from a subjective viewpoint, just like in non-MWI theories. In either case, over repeated iterations, to maximize your expected payout, the best strategy is to place bets in accordance with expecting to become one of the typical copies.

Expecting to become all of the copies does not make sense – it just comes about from a limitation of our language in describing such a situation.

 

[PeterDonis]

Imagine we had perfect cloning machines.

Note that, by the quantum no-cloning theorem, this is not possible. So this aspect of the analogy does not carry over to the quantum case. That should be kept in mind when interpreting it.

 

[akvadrako]

Note that, by the quantum no-cloning theorem, this is not possible. So this aspect of the analogy does not carry over to the quantum case. That should be kept in mind when interpreting it.

Are you saying that the versions of each "future you" in the different branches cannot be perfect copies?

 

[PeterDonis]

Are you saying that the versions of each "future you" in the different branches cannot be perfect copies?

In the sense of your classical analogy, they can't be perfect copies. In quantum terms, "you" are entangled with what you are observing, and each "future you" is the "you" degrees of freedom in one particular branch of the entangled wave function. So strictly speaking, none of the "future yous" have a definite state at all; only the overall entangled wave function is in a definite state. (Note that this is one of the issues with the MWI, explaining how we experience definite outcomes even though no individual branch of the wave function has a definite state at all.) Certainly no "copying" is going on in the quantum wave function; as I have already said, unitary evolution can't do that.

Even if we assume there is some way of getting around that difficulty, each "future you" experiences a different result of whatever measurement we're talking about, so they aren't perfect copies in that sense either.

 

[akvadrako]

Even if we assume there is some way of getting around that difficulty, each "future you" experiences a different result of whatever measurement we're talking about, so they aren't perfect copies in that sense either.

Indeed, better not to say they are perfect; but a clone that's good enough so it can reasonably think it's a future you.

And better not to say copies, but perhaps more future versions. Even though there is no copying going on, it's the orthogonal differences between the different branches that let's us say the branching tends to give us more branches in the future compared to the past, even assuming a diverging view.

 

[PeterDonis]

Even though there is no copying going on, it's the orthogonal differences between the different branches that let's us say the branching tends to give us more branches in the future compared to the past

As long as you're willing to ignore or hand-wave the fact that none of the branches individually has a definite state at all, yes.

 

[Moes]

These two scenarios are very philosophically different

You are getting into many philosophical questions, many which we already are confused about. It’s not even clear whether your two scenarios are at all philosophically different.

If there are two identical versions of you are there two of you or one?

Expecting to become all of the copies does not make sense – it just comes about from a limitation of our language in describing such a situation.

I don’t think it makes any more sense to expect to become only one of the copies.

If the first version is true, philosophy has a lot of work to do on what MWI means for individuals

Even without MWI philosophy has a lot of work to do. Why should you care about your future self/selves? Even if you do care about it why should you care about your own future self more than you care about anyone else’s? What makes you the same you today and tomorrow?

Before we have answers to all these questions I think it’s pointless to ask specifically about MWI.

 

[PeterDonis]

Even without MWI philosophy has a lot of work to do. Why should you care about your future self/selves? Even if you do care about it why should you care about your own future self more than you care about anyone else’s? What makes you the same you today and tomorrow?

Even if philosophy hasn't come up with what it believes to be good answers to all these questions (and I'm not sure all philosophers would agree with that--I think some think they, at least, do have good answers to them), our ordinary everyday view of things has reasonable pragmatic answers to them. Given that, it's reasonble to ask what, if any, impact the MWI has on those reasonable pragmatic answers. That is what I take the OP to be doing in this thread.

Before we have answers to all these questions I think it’s pointless to ask specifically about MWI.

Since this is your opinion, please do not post further in this thread, since you are basically saying the thread is pointless. Others may disagree, and they are the ones who should be posting here.

 

[Moes]

since you are basically saying the thread is pointless

Sorry if this is what it sounded like I was saying, its not at all what I was trying to say.

our ordinary everyday view of things has reasonable pragmatic answers to them. Given that, it's reasonble to ask what, if any, impact the MWI has on those reasonable pragmatic answers

I agree. My opinion is, like others already explained in this thread, that there is basically no impact that MWI has on those reasonable pragmatic answers.

 

[akvadrako]

As long as you're willing to ignore or hand-wave the fact that none of the branches individually has a definite state at all, yes.

I am willing to do that since I would say branching is just an approximate and convenient description; only the universe as a whole is independently consistent.

 

[PeterDonis]

My opinion is, like others already explained in this thread, that there is basically no impact that MWI has on those reasonable pragmatic answers.

That's fine, but it's very different from what you said in your previous post.

Also, please be aware that this is not a philosophy forum and general issues of philosophy are off topic here.

 

[PeterDonis]

I would say branching is just an approximate and convenient description; only the universe as a whole is independently consistent.

Does this include your conscious experience? You are aware, I take it, that according to the MWI, "you" have different conscious experiences in each individual branch, and that must be the case even though "you" do not have a definite state in each individual branch.

 

[Grinkle]

according to the MWI, "you" have different conscious experiences in each individual branch,

Does MWI require (I think the answer is yes, but I am not asking rhetorically, I may be incorrect) that any conceivable state of mind of the human race be allowed?

For instance, does MWI insist that there is a branch somewhere in which immediately after I post this reply I will spontaneously become an ardent advocate of flat Earth and instead of being banned from PF for nonsensical postings I will be hailed as a visionary by all of the PF mentors?

Absurdity may not be a barrier to something being real, but MWI seems to require so much to exist that its very hard for me to accept it as possible. My example is intended both tongue-in-cheek and also as a serious question - do such branches exist, according to MWI?

Sort of poking Occam right in the eye, if so.

 

[PeterDonis]

Does MWI require (I think the answer is yes, but I am not asking rhetorically, I may be incorrect) that any conceivable state of mind of the human race be allowed?

No, only ones that correspond to something with nonzero probability amplitude in the wave function.

For instance, does MWI insist that there is a branch somewhere in which immediately after I post this reply I will spontaneously become an ardent advocate of flat Earth and instead of being banned from PF for nonsensical postings I will be hailed as a visionary by all of the PF mentors?

Only if there is a nonzero probability amplitude in the wave function for that transition. You would be a better judge than I am of whether that is the case.

 

[Grinkle]

You would be a better judge than I am of whether that is the case.

Ha! I've likely made more ridiculous posts with far less awareness. ;-)

Only if there is a nonzero probability amplitude in the wave function for that transition.

OK - this can potentially rescue MWI for me. I can imagine that human minds operate to some degree as equilibrium restoring machines, and this mechanism will drive the probability of flatly absurd human behavior scenarios to zero. Like the laws of physics driving the probablility of impossible physics branches to zero.

 

[akvadrako]

Does this include your conscious experience? You are aware, I take it, that according to the MWI, "you" have different conscious experiences in each individual branch, and that must be the case even though "you" do not have a definite state in each individual branch.

In terms of consciousness, I don't see why according to the MWI anything would be different. I can just guess what must be required to explain it; maybe it can't be described as a classical state or even one branch, but the experience of continuously branching must be taken into account.

 

[Quantumental]

In terms of consciousness, I don't see why according to the MWI anything would be different. I can just guess what must be required to explain it; maybe it can't be described as a classical state or even one branch, but the experience of continuously branching must be taken into account.

In your view, what does this mean?

Either Person A becomes Person B and C, or they don't. There is literally no other option. If both outcomes (persons) are equally real, how can you say that either of them is 'more likely' to experience a certain outcome? This is where MWI has not progressed since my decade-old post which was quoted in this thread.

Since we cannot rely on branch counting, how can you logically defend X over Y outcome in any quantum mechanical probabilistic scenario? If both outcomes are equally real, by definition, there cannot be a 'preferred' outcome...

 

[PeterDonis]

In terms of consciousness, I don't see why according to the MWI anything would be different.

We have no actual theory of consciousness in physical terms, so of course we don't know, but one thing that would seem to be required is that a physical system that is having some definite conscious experience should be in some definite physical state. And that is not true of an individual branch of the wave function in the MWI.

maybe it can't be described as a classical state or even one branch, but the experience of continuously branching must be taken into account.

But nobody has any such experience of continuously branching.

 

[akvadrako]

But nobody has any such experience of continuously branching.

I don't know how you can know this; I certainly don't know it about myself. But I think the lack of any model for consciousness means it isn't a good avenue for discussion.

 

[akvadrako]

In your view, what does this mean?

Either Person A becomes Person B and C, or they don't. There is literally no other option. If both outcomes (persons) are equally real, how can you say that either of them is 'more likely' to experience a certain outcome? This is where MWI has not progressed since my decade-old post which was quoted in this thread.

Since we cannot rely on branch counting, how can you logically defend X over Y outcome in any quantum mechanical probabilistic scenario? If both outcomes are equally real, by definition, there cannot be a 'preferred' outcome...

I find several of the models for weighing outcomes satisfactory, but think it's a bit off-topic so won't get into it. Research hasn't stopped along these lines either; for example there is a paper from November which proposes an alternative way to count: Branch-counting in the Everett interpretation of quantum mechanics from Simon Saunders.

 

[PeterDonis]

I don't know how you can know this; I certainly don't know it about myself.

It seems obvious to me.

I think the lack of any model for consciousness means it isn't a good avenue for discussion.

Yes, fair point.

 

[hungrybear]

Thanks for the replies again.

I don't think you can avoid a model in which if Person A splits then they are the same as the two people they split into, even though those two people are now separate from each other, and don't experience each others perceptions. From person A's perspective, upon being split they either cease to exist or they become two separate selves, there's no reason why they would become only B or C. From the perspective of person A thinking about their future, they will become two separate entities and their future is both futures even though those entities will not experience each other once the split occurs. For person A to think of their future "I wonder if I will become person B or C?" doesn't make sense ontologically if B and C are made from directly splitting A.

If you're coming from an materialist perspective, this works just as well with particles. If you literally split an electron, it doesn't make sense to say which half of the electron will the original electron become? If you split the particles you are made of, from a materialist viewpoint you would become both people.

But you're right we're straying into philosophy here.

Peter I think if I'm following you when you say nothing splits and MWI is a temporal unity, does that mean that many world theories effectively require a block universe, with no flow of time? This is what David Deustch advocates.

In this case my scenarios become different again. An electron spin is measured and:

1. In scenario one, I am a unified person in one unified world and after the experiment there are two people like me, each of which experiences a different outcome. There has been no split because all times exist simultaneously so the me in the first timeframe and the two people in the next time frame have in some sense always existed but don't move through time.

2. In scenario two, there are already two versions of me but their experiences have been identical, after the experiment there are two further people like me, each of which experiences a different outcome. There is no progression of time but each possible past and future was already a separate world so in a sense there are four version of me, two before the experiment, two after, it's just the two versions after the electron experiment are not in identical universes, one experiences spin up, one experiences spin down.

Another question - does MWI mean there could be an extremely unlikely universe in which there is perpetual motion / no end of the universe scenario? My understanding is quantum events can extremely rarely disobey the laws of thermodynamics?

 

[PeterDonis]

if I'm following you when you say nothing splits and MWI is a temporal unity

I said nothing splits. I didn't say anything about MWI being "a temporal unity". I don't know what that means.

does that mean that many world theories effectively require a block universe

No.

In scenario one, I am a unified person in one unified world and after the experiment there are two people like me, each of which experiences a different outcome.

The MWI can be interpreted to say this, if you're willing to accept the implicit claim that each branch of the entangled wave function after measurement can contain a person that experiences a definite outcome at all, since neither branch has a definite state by itself. However:

There has been no split because all times exist simultaneously so the me in the first timeframe and the two people in the next time frame have in some sense always existed but don't move through time.

No. The MWI doesn't say anything like this. The MWI says there has been no split because the time evolution is always unitary, and a unitary operation can't "split" or "copy" anything. All that has happened is entanglement. That's it.

In scenario two, there are already two versions of me but their experiences have been identical, after the experiment there are two further people like me, each of which experiences a different outcome.

The MWI can also be interpreted to say this, with the same caveat as I gave for scenario one above. In other words, the MWI doesn't really see any difference between the two.

There is no progression of time but each possible past and future was already a separate world so in a sense there are four version of me, two before the experiment, two after, it's just the two versions after the electron experiment are not in identical universes, one experiences spin up, one experiences spin down.

The MWI doesn't say anything like any of this.

 

[Grinkle]

@hungrybear I don't think Unitary means what you are interpreting it to mean, but I'm not sure what your interpretation is.

 

[PeroK]

Another question - does MWI mean there could be an extremely unlikely universe in which there is perpetual motion / no end of the universe scenario?

MWI is not about unlikelihoods in that sense. The laws of physics remain as they are, except that every probabilistic outcome is realized (in some sense). There would be no branch in which you could rely on unlikely outcomes to continue.

This raises the question about the physical significance of these branches compared to the "normal" branches. To take an example:

You park your car overnight and wake up the next morning. There are, let's say, two reasons that your car is not there.

1) It's been stolen. That has a probability of, say, 1/10,000. Which corresponds to an overnight theft every 30 years.

2) It's vanished due to "an improbable sequence of quantum events". I can't write down a probablity for that because it's too small.

Leaving MWI aside, what is the physical significance of 2)? And, in MWI, what is the physical significance that in some sense a branch exists where your car has vanished into thin air overnight? You'd just assume it was stolen in any case!

 

[stevendaryl]

MWI is not about unlikelihoods in that sense. The laws of physics remain as they are, except that every probabilistic outcome is realized (in some sense). There would be no branch in which you could rely on unlikely outcomes to continue.

This raises the question about the physical significance of these branches compared to the "normal" branches. To take an example:

You park your car overnight and wake up the next morning. There are, let's say, two reasons that your car is not there.

1) It's been stolen. That has a probability of, say, 1/10,000. Which corresponds to an overnight theft every 30 years.

2) It's vanished due to "an improbable sequence of quantum events". I can't write down a probablity for that because it's too small.

Leaving MWI aside, what is the physical significance of 2)? And, in MWI, what is the physical significance that in some sense a branch exists where your car has vanished into thin air overnight? You'd just assume it was stolen in any case!

I don’t have an answer, but I would like to point out that there could be a “many worlds” interpretation of classical probability, as well. To simplify things, let’s assume a world that is deterministic except for one thing: There is a coin that can be flipped so tgst the outcome, heads or tails, is completely unpredictable, with a 50/50 chance if heads or tails.

Now, suppose that every time that you flip this coin, what really happens is that two copies of the universe are created. In one copy, the result is heads, and in the other, the result is tails.

Now there are two universes, slightly different. Any time that a coin is flipped in any universe, that universe is copied and made different by the results of that coin flip.

As far as someone living in the original universe is concerned, the existence of the alternate universes makes no difference. He might as well think of his as the only one. Of course, absolutely any universe can equally well consider itself to be the original.

So in this many-worlds model, the multiverse evolves deterministically, while each universe appears to its inhabitants to evolve nondeterministically.

 

[Nugatory]

It strikes me that most other interpretations keep shy of making outlandish unverifiable claims.

They all make unverifiable claims - that's what makes them interpretations. To the extent that they help us develop a mental model what the math is telling us in any given problem that's OK - it's what interpretations are for.

"Outlandish" is very much in the eye of the beholder (or as I've said many times before there is something to dislike about every interpretation). They all resolve the measurement problem with some form of "and then a miracle happens". MWI provides a consistent mathematical treatment of the miracle, unlike - for example - the relativity-defying unmotivated magical abandonment of unitary evolution that we find in collapse interpretations. Which do you find more outlandish? And is that not basically an aesthetic judgment?

 

[CoolMint]

They all make unverifiable claims - that's what makes them interpretations. To the extent that they help us develop a mental model what the math is telling us in any given problem that's OK - it's what interpretations are for.

"Outlandish" is very much in the eye of the beholder (or as I've said many times before there is something to dislike about every interpretation). They all resolve the measurement problem with some form of "and then a miracle happens". MWI provides a consistent mathematical treatment of the miracle, unlike - for example - the relativity-defying unmotivated magical abandonment of unitary evolution that we find in collapse interpretations. Which do you find more outlandish? And is that not basically an aesthetic judgment?

Yup. It is. Still people have been trying to harness the quantum weirdness and use its potentials. If what I have been reading is right, quantum computing has now been proven feasible. Quantum states, for all practical reasons, appear to have a reality of their own. Its major hurdle is what is perceived as 'decoherence' which like measurement also appears irreversible. If they can cool down the qubit and isolate it well enough, the future is quantum. From computers to tv's simulating virtual reality via goggles in highest resolution to cars and the internet. I am modestly optimistic that the future of the human race is quantum and with its endless practical applications, interpreting its essence will likely be easier.

 

[physika]

But, as a realist, the only objectively real world is the one experienced. Why should any alternative reality concern me based on my concrete experience?

Experencied by another "one".

 

[hutchphd]

Quantum states, for all practical reasons, appear to have a reality of their own.

What does that mean? They describe only themselves? This would not seem useful.

I am modestly optimistic that the future of the human race is quantum

I am equally modestly certain that the past has also been quantum. With respect, I find these pronouncements meaningless .

 

[CoolMint]

What does that mean? They describe only themselves? This would not seem useful.

No.

I am equally modestly certain that the past has also been quantum. With respect, I find these pronouncements meaningless .

One sentence can be meaningless when you remove the relevant context.
You should quote the whole comment I made(as I do with your comments) without removing the context so that it makes sense. The context can make a world of difference.

 

[hutchphd]

OK

Yup. It is. Still people have been trying to harness the quantum weirdness and use its potentials. If what I have been reading is right, quantum computing has now been proven feasible. Quantum states, for all practical reasons, appear to have a reality of their own. Its major hurdle is what is perceived as 'decoherence' which like measurement also appears irreversible. If they can cool down the qubit and isolate it well enough, the future is quantum. From computers to tv's simulating virtual reality via goggles in highest resolution to cars and the internet. I am modestly optimistic that the future of the human race is quantum and with its endless practical applications, interpreting its essence will likely be easier.

I find the highlighted text meaningless word salad . Please elucidate.
.

 

[hutchphd]

I have recently remembered this bit of Feynman wisdom. I believe it is part of the Cornell Messenger Lectures:


Drop the Mic.

 

[CoolMint]

OK
I find the highlighted text meaningless word salad . Please elucidate.
.

You need to understand the developments in quantum computing.
Quantum computers store the non-binary information in quantum states. You can find further info in the links provided in the wiki article. https://en.m.wikipedia.org/wiki/Quantum_computing

 

[hutchphd]

All computers store information in quantum states.
I was hoping you could make sense out of a statement that makes no sense to me. It was, after all, your statement.
I have taught both undergrad and graduate quantum mechanics courses. Yet there are parts of quantum computing I do not think I understand, so I already know that I need to "understand" it.

 

[CoolMint]

All computers store information in quantum states.
I was hoping you could make sense out of a statement that makes no sense to me. It was, after all, your statement.
I have taught both undergrad and graduate quantum mechanics courses. Yet there are parts of quantum computing I do not think I understand, so I already know that I need to "understand" it.

Computers based on transistors like yours store binary information in the transistors' gates. Not in quantum states. The computers of today do not employ quantum mechanics, but rather try to prevent it. E.g. leaking 2nm transistors due to quantum tunneling.

https://en.m.wikipedia.org/wiki/2_nm_process

The separation between gates and insulation becomes too small and quantum tunneling is very hard to prevent.

 

[PeterDonis]

Computers based on transistors like yours store binary information in the transistors' gates. Not in quantum states.

If you adopt a realist interpretation of quantum states (which is implied by your statement that "quantum states have a reality of their own"), then the states of the transistor gates are quantum states, since the state of any real object is a quantum state. So your statement above would be false as you state it.

The computers of today do not employ quantum mechanics, but rather try to prevent it

This is also false as you state it, since "quantum mechanics" underlies the behavior of everything, including transistors and computers.

I think you need to be more careful in how you state things. It would be valid to state that today's digital computers do not depend on any quantum interference effects, and try to prevent things like quantum tunneling from happening, since those things reduce the accuracy and reliability of the computers. But that is not what either of the statements of yours that I quoted above say.

 

[CoolMint]

If you adopt a realist interpretation of quantum states (which is implied by your statement that "quantum states have a reality of their own"), then the states of the transistor gates are quantum states, since the state of any real object is a quantum state. So your statement above would be false as you state it.This is also false as you state it, since "quantum mechanics" underlies the behavior of everything, including transistors and computers.

I think you need to be more careful in how you state things. It would be valid to state that today's digital computers do not depend on any quantum interference effects, and try to prevent things like quantum tunneling from happening, since those things reduce the accuracy and reliability of the computers. But that is not what either of the statements of yours that I quoted above say.

Quantum theory was never relevant to classical computers until the time when tunneling become a problem. Clearly everything is quantum in nature but that doesn't mean that a kitchen knife uses quantum mechanics. Even if its constituents are quantum in nature.
There is still a field of physics known as classical physics and it is no more false than a knife being a quantum object. A classical computer is not a quantum object unless weird discussions among interpretations are concerned.

 

[PeterDonis]

Clearly everything is quantum in nature but that doesn't mean that a kitchen knife uses quantum mechanics.

According to your idiosyncratic definition of what "uses quantum mechanics" means, perhaps. But as you can see from others' responses in this thread, your idiosyncratic use of language just makes it difficult for other people to understand what you are saying. That is why I said I think you need to be more careful.

 

[gmax137]

Has anyone done an estimate of how many worlds there are now? If the universe is made of say,10^80 protons and electrons that have been interacting for about 14 billion years, what does the number come to? Isn't it unimaginably huge?

How many bifurcations does an individual human experience every day? Asking for a friend :)