What types of parallel universe do you find most plausible?

[pulstar]

Different interpretations based on their different framework predict various different outcomes. Thankfully that can be tested. Based on experimental data Born rule is real and physics based on Copenhagen led all the way to here. In order to explain probabilistic nature of Copenhagen it is very unscientific to explain it in terms of MWI, not to mention claiming then that Born rule is not more real than MWI.

I'm not sure all ideas about MWI can be tested. Concerning Born rule and MWI probability postulate, if you crossbread our knowledge about quantum physics, math and statistics we possess thus far, you can only conclude that both have the same chance to be correct, there are a couple of works I found. The real problem with MWI is their main proponents slightly vary in how they interpret the idea. Some MWI ideas can't be tested yet, some never would be possible. That's what drawn away many physicists from even considering it, as they argue it leads to metaphysics. But lets not forget that MWI was deeply discouraged from any educational facilities for most of the 20th century and this might be another reason why it was not made more breakthroughs in that direction. There were many other similar subjects and people kept away from public that made the discoveries and simply disappeared because academia at that time didn't consider it noteworthy. There are also some positives about MWI not found in standard interpretation, like the fact it retains the theory of relativity. Some folks argue that MWI don't follow Ockham's razor, as it imposes more hypothesis, but from purely mathematical side it imposes less hypothesis than standard interpretation. Anyhow, exact explaination of quantum physics phenomenon is still unknown, I'm just keeping my mind open for any idea and this thread is about philosophy of cosmology more than anything else. For now, my view here is strictly agnostic.

[Westbrook]

This is still better than 17,000 identical "what countries do I pass in" or "classify my neighbor's uncle" anthrotard threads

I write this while drinking a big stein of Heineken:

You guys are all dumb, using big mumbo jumbo that you clearly do not understand in attempt to look "smart".
Why get specific on such a topic that is so speculative at best? String theory has only been scratched and we hardly know 10% of the implications of quantum mechanics.

It does point that multiverses exist and that's enough. Narrowing it down beyond that is absurd.

Quantum physics hits a giant brick wall where only Buddhist philosophy will fill the gaps.

[Insuperable]

I'm not sure all ideas about MWI can be tested. Concerning Born rule and MWI probability postulate, if you crossbread our knowledge about quantum physics, math and statistics we possess thus far, you can only conclude that both have the same chance to be correct, there are a couple of works I found. The real problem with MWI is their main proponents slightly vary in how they interpret the idea. Some MWI ideas can't be tested yet, some never would be possible. That's what drawn away many physicists from even considering it, as they argue it leads to metaphysics. But lets not forget that MWI was deeply discouraged from any educational facilities for most of the 20th century and this might be another reason why it was not made more breakthroughs in that direction. There were many other similar subjects and people kept away from public that made the discoveries and simply disappeared because academia at that time didn't consider it noteworthy. There are also some positives about MWI not found in standard interpretation, like the fact it retains the theory of relativity. Some folks argue that MWI don't follow Ockham's razor, as it imposes more hypothesis, but from purely mathematical side it imposes less hypothesis than standard interpretation. Anyhow, exact explaination of quantum physics phenomenon is still unknown, I'm just keeping my mind open for any idea and this thread is about philosophy of cosmology more than anything else. For now, my view here is strictly agnostic.

Look... not only is MWI waste of time, so are most other interpretations of QM (except Copenhagen). At best none of them should be taken for real, but some perhaps could be used as a practical tool to solve some non-relativistic problems. Regarding the bolded ... MWI simply reduces number of hypothesis and replaces them with one big giant scratch head hypothesis, makes you think some six year old child came up with it. Like I said elegant, but futile. In a similar way the Standard Model of (Particle) Physics is not elegant which in a way made physicists to come up with elegant theories of supersymmetry and string theory, but turned out empty handed. Decades of work gone to waste (lulz at Warchief only scratched the surface). Even Witten is turning back on such theories.

Anyhow, exact explaination of quantum physics phenomenon is still unknown, I'm just keeping my mind open for any idea and this thread is about philosophy of cosmology more than anything else. For now, my view here is strictly agnostic

The exact explanation of all weird phenomena (collapse, wave-particle duality etc) is not unknown. It can be explained within the context of the Quantum field theory. Quantum field theory is a generalization of Quantum Mechanics. It is a relativistic QM. Schrodinger equation is a non-relativistic equation. Klein-Gordon equation is a relativistic Schrodinger equation. Quantum field theory says that there are no such thing as particles. There are only fields of energy. There is a photon field which permeates the entire Universe. There is an electron field which permeates the entire Universe, proton field etc. And what we think of as particles are simply excitations or concentrations of a corresponding field. Whenever these fields come into contact with each other an exchange of energy and 'momentum' occurs. At the beginning of the Universe there was probably only one field (unified theory everyone searches for) which broke into more fields as the Universe got older. Quantum field theory led to the Standard Model of (particle) physics. Also, quantum electrodynamics is the most exact scientific theory known to man. If a physicist wants to do non-relativistic physics (like condensed matter physics) he won't do it according to the rules of quantum field theory, but according to the rules of more practical quantum physics like quantum mechanics and along with it according to the rules of Copenhagen interpretation.

You are now probably wondering wtf why do we have all these interpretations of quantum mechanics. We have them because many physicists can't cope with the physical and mathematical abstractness of the quantum field theory. They prefer particles instead of fields, but are more and more forced to except that the field is the most fundamental constituent. The other problem is the problem of entanglement. It is an experimental fact, but how to incorporate it into the quantum field theory is still not precisely known, but it will be done sooner or later. On the other hand, interpretations except Copenhagen which doesn't even want to do that, lack incorporation into the quantum field theory, not to mention reproducing the Standard Model of physics.

The greatest physicists of the 20th century realized early on it is stupid to break heads about understanding the most fundamental reality. All you need is to take certain aspects of quantum physics (aka field theory) for granted, do the math, do numbers and in the end just do what they say.

As you probably know your body mass is equal to mass of protons and neutrons in your body. Electron mass can be neglected. Since protons and neutrons are made of quarks you'd think that your mass is equal to masses of all quarks in your body. But that is not so. Experiments confirm that mass of quarks in protons or neutrons is just 1-2% of mass of proton and neutron respectively. Higgs field gives quarks that 1-2% mass. Kinetic energy of quarks moving at relativistic speeds inside protons and neutrons contributes to about 30 or 40% to mass of proton or neutron. 3% of our mass is attributed to vacuum fluctuations. The rest of our mass comes from other processes. Don't take me for granted, but I think some are still unknown. You are now probably wondering where does this kinetic and other energy coming from. It probably comes from the zero-point energy of the Universe.

This example alone should tell you about the importance of fields and the abstractness of quantum physics aka quantum field theory.

[pulstar]

Look... not only is MWI waste of time, so are most other interpretations of QM (except Copenhagen). At best none of them should be taken for real, but some perhaps could be used as a practical tool to solve some non-relativistic problems. Regarding the bolded ... MWI simply reduces number of hypothesis and replaces them with one big giant scratch head hypothesis, makes you think some six year old child came up with it. Like I said elegant, but futile. In a similar way the Standard Model of (Particle) Physics is not elegant which in a way made physicists to come up with elegant theories of supersymmetry and string theory, but turned out empty handed. Decades of work gone to waste (lulz at Warchief only scratched the surface). Even Witten is turning back on such theories.



The exact explanation of all weird phenomena (collapse, wave-particle duality etc) is not unknown. It can be explained within the context of the Quantum field theory. Quantum field theory is a generalization of Quantum Mechanics. It is a relativistic QM. Schrodinger equation is a non-relativistic equation. Klein-Gordon equation is a relativistic Schrodinger equation. Quantum field theory says that there are no such thing as particles. There are only fields of energy. There is a photon field which permeates the entire Universe. There is an electron field which permeates the entire Universe, proton field etc. And what we think of as particles are simply excitations or concentrations of a corresponding field. Whenever these fields come into contact with each other an exchange of energy and 'momentum' occurs. At the beginning of the Universe there was probably only one field (unified theory everyone searches for) which broke into more fields as the Universe got older. Quantum field theory led to the Standard Model of (particle) physics. Also, quantum electrodynamics is the most exact scientific theory known to man. If a physicist wants to do non-relativistic physics (like condensed matter physics) he won't do it according to the rules of quantum field theory, but according to the rules of more practical quantum physics like quantum mechanics and along with it according to the rules of Copenhagen interpretation.

You are now probably wondering wtf why do we have all these interpretations of quantum mechanics. We have them because many physicists can't cope with the physical and mathematical abstractness of the quantum field theory. They prefer particles instead of fields, but are more and more forced to except that the field is the most fundamental constituent. The other problem is the problem of entanglement. It is an experimental fact, but how to incorporate it into the quantum field theory is still not precisely known, but it will be done sooner or later. On the other hand, interpretations except Copenhagen which doesn't even want to do that, lack incorporation into the quantum field theory, not to mention reproducing the Standard Model of physics.

The greatest physicists of the 20th century realized early on it is stupid to break heads about understanding the most fundamental reality. All you need is to take certain aspects of quantum physics (aka field theory) for granted, do the math, do numbers and in the end just do what they say.

As you probably know your body mass is equal to mass of protons and neutrons in your body. Electron mass can be neglected. Since protons and neutrons are made of quarks you'd think that your mass is equal to masses of all quarks in your body. But that is not so. Experiments confirm that mass of quarks in protons or neutrons is just 1-2% of mass of proton and neutron respectively. Higgs field gives quarks that 1-2% mass. Kinetic energy of quarks moving at relativistic speeds inside protons and neutrons contributes to about 30 or 40% to mass of proton or neutron. 3% of our mass is attributed to vacuum fluctuations. The rest of our mass comes from other processes. Don't take me for granted, but I think some are still unknown. You are now probably wondering where does this kinetic and other energy coming from. It probably comes from the zero-point energy of the Universe.

This example alone should tell you about the importance of fields and the abstractness of quantum physics aka quantum field theory.

If you wish to talk about QFT, I'm not the right person. I simply read few ideas about some selected chapters, so I know very generalized what you speak of. I also read a good book on non-relativistic standard interpretation of quantum mechanics, so I think I got decent understanding regarding elementary Copenhagen principles. Like I said, I'm open to other interpretation so far, because I didn't had opportunities to read whole papers, just popular science brief explainations which can be very wrong. That might change when I read the MWI paper and one decent notebook on QFT I've found.

[JosephK]

I suppose (1) is the only one remotely plausible, that an infinite universe will wield infinite parallel universes, exhausting all possibilities. But that's only if everything is, in infinity, as we understand it.

[Latinus]

I suppose (1) is the only one remotely plausible, that an infinite universe will wield infinite parallel universes, exhausting all possibilities. But that's only if everything is, in infinity, as we understand it.

[Red Pill]

If you wish to talk about QFT, I'm not the right person. I simply read few ideas about some selected chapters, so I know very generalized what you speak of. I also read a good book on non-relativistic standard interpretation of quantum mechanics, so I think I got decent understanding regarding elementary Copenhagen principles. Like I said, I'm open to other interpretation so far, because I didn't had opportunities to read whole papers, just popular science brief explainations which can be very wrong. That might change when I read the MWI paper and one decent notebook on QFT I've found.

Even if I have a scientific education, I don't have a background in physics, so I cannot discuss QFT in any depth, only quote what the experts say about the basics and maybe make some general observation. There are more than a dozen interpretations of Quantum Physics, without counting variants. The Copenhagen interpretation, as far as I know, is still one of the most popular but by no means consensus, and it is, and has been, criticized by many scientists, including Einstein. I personally like the Everett "multi-world" interpretation, but I cannot in any way say how much likely it is. I just like the idea that all possible alternatives congruent with the law of physics exist in separate universes. For instance there would be universes where the West never turned "woke". However, it's well possible that in such multiverse most universes would turn out worse than ours. "Worse" of course is very subjective. A universe where, for instance, the KT event never occurred would not have any humans, but it would be a better world in a dinosaur perspective.
Today most physicists support the Cosmic Inflation, which in turn seems to support a multiverse. However that doesn't necessarily mean that this multiverse is infinite, or even as big as some hypothesis postulate. For instance, one hypothesis assumed the existence of 10^500 universes, a number that defies imagination (to compare, there are estimates that the number of subatomic particles in the observable universe is around 10^120, every additional unit corresponding to a 10-fold increment). However other physicists have a more conservative view of the size of the multiverse, and believe that it would not be large enough to produce "copies" of ourselves. If I recall correctly, the late Stephen Hawking "converted" to the latter view in the last years of his life. Maybe even 10^500 would not be enough. If somebody likes the idea that there is somewhere a copy of you who successfully dated that high school flame, better hope that there is an infinite multiverse, or that the Everett interpretation is correct

[pulstar]

Even if I have a scientific education, I don't have a background in physics, so I cannot discuss QFT in any depth, only quote what the experts say about the basics and maybe make some general observation. There are more than a dozen interpretations of Quantum Physics, without counting variants. The Copenhagen interpretation, as far as I know, is still one of the most popular but by no means consensus, and it is, and has been, criticized by many scientists, including Einstein. I personally like the Everett "multi-world" interpretation, but I cannot in any way say how much likely it is. I just like the idea that all possible alternatives congruent with the law of physics exist in separate universes. For instance there would be universes where the West never turned "woke". However, it's well possible that in such multiverse most universes would turn out worse than ours. "Worse" of course is very subjective. A universe where, for instance, the KT event never occurred would not have any humans, but it would be a better world in a dinosaur perspective.
Today most physicists support the Cosmic Inflation, which in turn seems to support a multiverse. However that doesn't necessarily mean that this multiverse is infinite, or even as big as some hypothesis postulate. For instance, one hypothesis assumed the existence of 10^500 universes, a number that defies imagination (to compare, there are estimates that the number of subatomic particles in the observable universe is around 10^120, every additional unit corresponding to a 10-fold increment). However other physicists have a more conservative view of the size of the multiverse, and believe that it would not be large enough to produce "copies" of ourselves. If I recall correctly, the late Stephen Hawking "converted" to the latter view in the last years of his life. Maybe even 10^500 would not be enough. If somebody likes the idea that there is somewhere a copy of you who successfully dated that high school flame, better hope that there is an infinite multiverse, or that the Everett interpretation is correct

I got knowledge of mathematical tools to start dealing with this subject but I don't have time to read all the theory, even though I try to. Thus far I've read one book by Susskind and I started another by some guy from Cambridge on subject of Quantum Mechanics. I didn't reach QFT, but I check interesting videos, and ocassionally they have smart things to say, like Sabine's arguments against MWI (but also why its at least on par with Copenhagen):


And that's all what I meant by saying I'm agnostic. That's not to be confused by what some folks consider classical definition of agnosticism in quantum mechanics, namely quantum indeterminacy, which tries to give answer to the question about position of particle just before the measurement, and the answer goes something like:
"What sense can there be in making assertions about the status of a particle before a measurement, when the only way of knowing whether you were right is precisely to make a measurement, in which case what you get is no longer “before the measurement”?"

That last assertion was debunked by John Bell's experiment in 1965. The other two views often mentioned are: orthodox (answer is "the particle isn't really anywhere", that's Copenhangen) and realist ("the particle was at exact location A", this is where Einstein's claim was falling, it implies quantum mechanics is incomplete and lacks some hidden information, often called hidden variables). So what I mean is I'm agnostic between any two orthodox interpretations, because I knew realists position was experimentaly proved wrong. From my understanding MWI falls into orthodox view.

As for others views I already said they were all compatible and for new they seem equally likely to me except for the last one. In fact I believe (personal opinion) that holographic and simulated multiverse are something that sounds the most logical. At least philosophically. Steven Hawking was one of the founders of holographic multiverse idea.

[Insuperable]

Even if I have a scientific education, I don't have a background in physics, so I cannot discuss QFT in any depth, only quote what the experts say about the basics and maybe make some general observation. There are more than a dozen interpretations of Quantum Physics, without counting variants. The Copenhagen interpretation, as far as I know, is still one of the most popular but by no means consensus, and it is, and has been, criticized by many scientists, including Einstein. I personally like the Everett "multi-world" interpretation, but I cannot in any way say how much likely it is. I just like the idea that all possible alternatives congruent with the law of physics exist in separate universes. For instance there would be universes where the West never turned "woke". However, it's well possible that in such multiverse most universes would turn out worse than ours. "Worse" of course is very subjective. A universe where, for instance, the KT event never occurred would not have any humans, but it would be a better world in a dinosaur perspective.
Today most physicists support the Cosmic Inflation, which in turn seems to support a multiverse. However that doesn't necessarily mean that this multiverse is infinite, or even as big as some hypothesis postulate. For instance, one hypothesis assumed the existence of 10^500 universes, a number that defies imagination (to compare, there are estimates that the number of subatomic particles in the observable universe is around 10^120, every additional unit corresponding to a 10-fold increment). However other physicists have a more conservative view of the size of the multiverse, and believe that it would not be large enough to produce "copies" of ourselves. If I recall correctly, the late Stephen Hawking "converted" to the latter view in the last years of his life. Maybe even 10^500 would not be enough. If somebody likes the idea that there is somewhere a copy of you who successfully dated that high school flame, better hope that there is an infinite multiverse, or that the Everett interpretation is correct

10^500 number comes from string theory not Inflation if that is what you are implying. The idea that number represents other universes is just one of interpretations of it and hyped too. Anyway, very childish post and you didn't read anything I wrote.

I got knowledge of mathematical tools to start dealing with this subject but I don't have time to read all the theory, even though I try to. Thus far I've read one book by Susskind and I started another by some guy from Cambridge on subject of Quantum Mechanics. I didn't reach QFT, but I check interesting videos, and ocassionally they have smart things to say, like Sabine's arguments against MWI (but also why its at least on par with Copenhagen):

No interpretation is on par with Copenhagen and she doesn't say that. Copenhagen is not interpretation like others are. Copenhagen is more like set of rules. We already have definite interpretation of physics which can solve all problems. It is called the Quantum field theory.

And that's all what I meant by saying I'm agnostic. That's not to be confused by what some folks consider classical definition of agnosticism in quantum mechanics, namely quantum indeterminacy, which tries to give answer to the question about position of particle just before the measurement, and the answer goes something like:
"What sense can there be in making assertions about the status of a particle before a measurement, when the only way of knowing whether you were right is precisely to make a measurement, in which case what you get is no longer “before the measurement”?"

That last assertion was debunked by John Bell's experiment in 1965. The other two views often mentioned are: orthodox (answer is "the particle isn't really anywhere", that's Copenhangen) and realist ("the particle was at exact location A", this is where Einstein's claim was falling, it implies quantum mechanics is incomplete and lacks some hidden information, often called hidden variables). So what I mean is I'm agnostic between any two orthodox interpretations, because I knew realists position was experimentaly proved wrong. From my understanding MWI falls into orthodox view.

MWI falls nowhere, where did you get that? Probably from those who push MWI for whatever reason. The very problem in those views is in those very sentences ... the word particle. When we deal with low-energy physics or non-relativistic one we deal with particles. Such view is just a special case of a more general theory called quantum field theory which is a high energy physics or relativistic one. When you combine special theory and quantum mechanics fields comes out naturally.

Most physicists deal with low-energy physics. Most of them never touch upon many aspects of the quantum field theory. They only borrow ideas from quantum field theory here and there. Physicists who work with quantum field theory the most are obviously theoretical particle physicists and believe it or not most other physicists don't know quantum field theory. Next problem is that papers on quantum field theory and entanglement, locality etc are scarce. Those who do quantum field theory don't care about that and vice versa. From my understanding, based on all of that and more is why discrepancies lay.

Physicist Rodney Brooks wrote a book about quantum field theory and someone asked what people think of it. He wrote:

Coincidentally, I saw this question on Quora the same day I had visited the author of a major textbook on Quantum Field Theory – a book that has sold 8000 copies. (My book has only sold 4000, but it is moving up fast, and has a 4.4 star rating on Amazon.) I'm glad to say that he approves of my book and is very supportive of my efforts.
As for my own background, I do not pretend to be an expert in QFT. I learned it as a student of Julian Schwinger, the genius who perfected it (see Julian Schwinger). However I did my Ph.D. thesis with Nobel laureate Norman Ramsey, and went on to have a successful career working on the physics of medical imaging at the National Institutes of Health.
I freely admit that most “mainstream” physicists do not agree with my field view. Following Feynman, they prefer the particle picture, despite the fact that Feynman (as reported in my book) eventually converted to fields. When I gave a talk this year at the Czech Technical University, “What does the electron look like?” (under “Related Links” at Understand Physics Through Quantum Field Theory), very few in the audience accepted the field picture. Also very few had heard of Julian Schwinger.
I try to make it clear in the book that the use of color is strictly imaginary and has no relation to the colors similarly used in quantum chromodynamics. Fields are nothing more than properties of space, and most people (including me) have a hard time grasping the concept at first. Most readers find color a useful crutch to help picture the various fields. Art Hobson (another “mainstream” physicist) has called it “a stroke of pedagogical genius”.
Finally, the reason there are so many disparate quotes scattered in my book is that it is aimed at the lay reader. I quote Marilyn vos Savant – along with Joseph Heller, Bill Clinton, et al. – to illustrate how confusing the general public finds quantum physics and relativity, and quotes from physicists like Einstein, Feynman, Newton, etc. are there because I know my credentials are weak and I want to show that I’m not just whistling Dixie.
Please give it a try. I consider the neglect of QFT, the only theory that makes sense and resolves the paradoxes of relativity and QM, an intellectual tragedy of the highest magnitude. WAKE UP AND SMELL THE FIELDS.

https://www.quora.com/What-do-mainst...m-field-theory

Ironically, field view was present already in the the 1920s. Started with Dirac and others in 1926 and with Heisenberg and Pauli who further layed foundations of QFT in 1929 and 1930 building successful Lagrangian Quantum Field theory.
https://en.wikipedia.org/wiki/Second_quantization

And sadly almost 100 years later guy has to talk about this in his Faraday lecture or whatever it is because such view is not yet widely accepted.


For every theoretical particle physicist today and quantum field theorists, QFT is THE interpretation especially considering the example why I gave in the previous post.

[Red Pill]

10^500 number comes from string theory not Inflation if that is what you are implying. The idea that number represents other universes is just one of interpretations of it and hyped too. Anyway, very childish post and you didn't read anything I wrote.

Inflation is included in several versions of String Theory, Einstein. And I was discussing with Pulstar.