I Are the implications of MWI really this horrifying?

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  • #91
hutchphd said:
What does that mean? They describe only themselves? This would not seem useful.

No.

hutchphd said:
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.
 
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  • #92
OK

CoolMint said:
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.
.
 
  • #93
I have recently remembered this bit of Feynman wisdom. I believe it is part of the Cornell Messenger Lectures:


Drop the Mic.
 
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  • #94
hutchphd said:
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
 
  • #95
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.
 
  • #96
hutchphd said:
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.
 
  • #97
CoolMint said:
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.

CoolMint said:
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.
 
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  • #98
PeterDonis said:
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.
 
  • #99
CoolMint said:
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.
 
  • #100
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 :)
 
  • #101
gmax137 said:
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 :)
I'm not sure there is a consensus on whether the number of branches is finite, countable or uncountable. I believe Everett himself postulated bifurcation into uncountably infinite branches.
 
  • #102
PeroK said:
I believe Everett himself postulated bifurcation into uncountably infinite branches.
Well then in nearly all of them, the OP is not there. So the OP worrying about how things are going for him/her in these other worlds seems to miss the point. On the other hand, maybe there are some worlds where he/she is the king. And lives for ten thousand years. It's a glass half full thing.
 
  • #103
gmax137 said:
Well then in nearly all of them, the OP is not there. So the OP worrying about how things are going for him/her in these other worlds seems to miss the point. On the other hand, maybe there are some worlds where he/she is the king. And lives for ten thousand years. It's a glass half full thing.
Sure, especially if we believe that the origin of the galaxies is a series of quantum events in the early universe, then "most" branches do not have the Milky Way, Sun or Planet Earth, let alone an individual whose birth depended on a very specific set of macroscopic circumstances, which themselves were heavily dependent on quantum mechanical outcomes.

Taking about "being king" or "living for ten thousand years" may be missing the point. Even if there are such branches, then they must be statistically dominated by more normal outcomes.

That said, I'm not sure any of us has the capacity to make much sense of MWI from any sort of "human" perspective.
 
  • #104
PeroK said:
I'm not sure there is a consensus on whether the number of branches is finite, countable or uncountable. I believe Everett himself postulated bifurcation into uncountably infinite branches.
Everett’s original paper on what came to be known as the “Many-Worlds Interpretation” didn’t talk about branching. It talked about the state of the rest of the world relative to the state of the observer.
 
  • #106
Once again excuse my ignorance but what does MWI say about quantum fluctuations in the vacuum, the random appearance and annihilation of pairs of quantum particles? I've struggled to find something for the general reader on this.

Are the fluctuations deterministic in MWI theory? Do they happen differently in different worlds? Or does MWI theory accept these as random?
 
  • #107
hungrybear said:
Once again excuse my ignorance but what does MWI say about quantum fluctuations in the vacuum, the random appearance and annihilation of pairs of quantum particles? I've struggled to find something for the general reader on this.

Are the fluctuations deterministic in MWI theory? Do they happen differently in different worlds? Or does MWI theory accept these as random?
Professor Neumaier has written several articles on the misconceptions and myth of quantum fluctuations.

https://www.physicsforums.com/insights/misconceptions-virtual-particles/

https://www.physicsforums.com/insights/vacuum-fluctuation-myth/

In short, the fluctuations are not themselves quantum events or interactions; they are a heuristic aid to calculating the amplitudes for real quantum events.
 
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  • #108
hungrybear said:
what does MWI say about quantum fluctuations in the vacuum, the random appearance and annihilation of pairs of quantum particles?
This phenomenon (which, as @PeroK has noted, is often misdescribed and misunderstood) does not involve any measurements, so QM interpretations don't really say anything about it.
 
  • #109
CoolMint said:
Quantum theory was never relevant to classical computers until the time when tunneling become a problem.
I'm not sure that's true, @CoolMint. As I recall my comp sci history, transistor design - even the first one! - utilised QM. And I know that 'classical' computing is different to a quantum computer, but 'classical' does not mean QM wasn't / isn't needed for semiconductor design.
 

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