Fun fact, Hugh Everett is “E” Mark Oliver Everett’s father, lead singer of The Eels.
Came here for this :-D.
:-D
How the Many-Worlds Theory of Hugh Everett Split the Universe
71–80 of 122 posts
Re: How the Many-Worlds Theory of Hugh Everett Split the Universe
#72Earlier quoted context omitted.
The main difference is one of rhetoric: Copenhagen insists that experiments have single outcomes. MWI insists that experiments have multiple outcomes in point of metaphysical fact. Another difference is that the MWI has to explain the Born rule (which is problematic), whereas Copenhagen simply takes it as an axiom. http://blog.rongarret.info/2019/07/the-trouble-with-many-wor...
It should be noted though that few interpretations have an explanation for the born rule.
Actually most interpretations have the same explanations for the Born rule, it's just that people who study many worlds are more inclined to consider them. People who believe in Copenhagen don't care about this stuff.
For a recent high-quality example: https://www.nature.com/articles/s41467-019-09348-x
Re: How the Many-Worlds Theory of Hugh Everett Split the Universe
#73Earlier quoted context omitted.
The main difference is one of rhetoric: Copenhagen insists that experiments have single outcomes. MWI insists that experiments have multiple outcomes in point of metaphysical fact. Another difference is that the MWI has to explain the Born rule (which is problematic), whereas Copenhagen simply takes it as an axiom. http://blog.rongarret.info/2019/07/the-trouble-with-many-wor...
Conversely, Copenhagen-like explanations need to explain (or postulate) a decoherence/collapse operation that violates all the usual rules of QM: it would be non-time-symmetric, non-unitary, likely non-local (propagating faster than light), ...
Non-locality is practically axiomatic if you understand Bell's Inequalities, and doesn't require true FTL signalling.
MWI doesn't really solve either the locality or the FTL problem. If you're going to believe in MWI you have to explain how an entire universe appears instantaneously, identical in every way to another universe, except for one almost insignificant difference in exactly one quantum interaction.
That's a rather larger and more serious signalling and information transfer problem than the much smaller-scale non-locality required to explain entanglement.
Re: How the Many-Worlds Theory of Hugh Everett Split the Universe
#74Earlier quoted context omitted.
"self-location uncertainty" seems to still assume what is basically the Born rule: >MWI probability postulate: The probability of self-location in a world with a given set of outcomes is the absolute square of that world’s amplitude. ( http://philsci-archive.pitt.edu/14389/1/defence-location-unc... ) It just applies the absolute square of the amplitudes to the chance of being in a given world rather than the chance o…
Fair enough - I'm not a physicist or read papers on physics. I'm just trying to re-tell the best version of the theories as I've understood them by steel-manning arguments laid out (by scientists that have some media exposure), rather than try to straw-man each theory with prima-facie criticisms that have already been answered. I know MWI has significant gaps, this appears to be one of the biggest. thank you for citi…
Ta. As far as I can tell a lack of an explanation for the Born rule is a feature of all quantum interpretations, not just many worlds. It's pretty much the central mystery of quantum mechanics.
Re: How the Many-Worlds Theory of Hugh Everett Split the Universe
#75Earlier quoted context omitted.
Here's a quote from David Deutsch's "The Fabric of Reality": "When I introduced tangible and shadow photons I apparently distinguished them by saying that we can see the former, but not the latter. But who are ‘we’? While I was writing that, hosts of shadow Davids were writing it too. They too drew a distinction between tangible and shadow photons; but the photons they called ‘shadow’ include the ones I called ‘tangi…
Deutsch may believe that. (Heck, I believe it). It's a natural interpretation of the MWI wavefunction. But it is an interpretation, a layer on top of the physical claims, a model - not a mandatory part of MWI. Deutsch may interpret a given wavefunction as describing a particular ensemble of 'tangible' and 'shadow' objects, but someone who interprets that same wavefunction a different way (but agrees on the same wavef…
That makes MWI a "no true parallel Scotsman" interpretation.
Either the other versions of reality are tangible, or they're not. If they're just abstractions, you have't solved the problem - you've taken a long way around a circular argument that starts with the wavefunction and ends with it doing something that results in a measurement, maybe.
Unfortunately explaining how that happens is the problem you're trying to solve. It's not an answer to the problem.
If they are real, there are all kinds of other issues, the Born Rule being the most obvious.
Re: How the Many-Worlds Theory of Hugh Everett Split the Universe
#76Earlier quoted context omitted.
Here's a quote from David Deutsch's "The Fabric of Reality": "When I introduced tangible and shadow photons I apparently distinguished them by saying that we can see the former, but not the latter. But who are ‘we’? While I was writing that, hosts of shadow Davids were writing it too. They too drew a distinction between tangible and shadow photons; but the photons they called ‘shadow’ include the ones I called ‘tangi…
MWI provides a clear, comprehensive explanation for all of the “weird” quantum phenomenon. Beyond that, this quote from FoR [1] convinced me: “To those who still cling to a single-universe world-view, I issue this challenge: explain how Shor’s algorithm works. I do not merely mean predict that it will work, which is merely a matter of solving a few uncontroversial equations. I mean provide an explanation. When Shor’s…
"Interpretations of quantum mechanics, unlike Gods, are not jealous, and thus it is safe to believe in more than one at the same time. So if the many-worlds interpretation makes it easier to think about the research you’re doing in April, and the Copenhagen interpretation makes it easier to think about the research you’re doing in June, the Copenhagen interpretation is not going to smite you for praying to the many-worlds interpretation. At least I hope it won’t, because otherwise I’m in big trouble."
- Peter Shor (https://www.scottaaronson.com/blog/?p=218#comment-5753)
Re: How the Many-Worlds Theory of Hugh Everett Split the Universe
#77Earlier quoted context omitted.
Here's a quote from David Deutsch's "The Fabric of Reality": "When I introduced tangible and shadow photons I apparently distinguished them by saying that we can see the former, but not the latter. But who are ‘we’? While I was writing that, hosts of shadow Davids were writing it too. They too drew a distinction between tangible and shadow photons; but the photons they called ‘shadow’ include the ones I called ‘tangi…
MWI provides a clear, comprehensive explanation for all of the “weird” quantum phenomenon. Beyond that, this quote from FoR [1] convinced me: “To those who still cling to a single-universe world-view, I issue this challenge: explain how Shor’s algorithm works. I do not merely mean predict that it will work, which is merely a matter of solving a few uncontroversial equations. I mean provide an explanation. When Shor’s…
If one die can have 6 values, how is it possible that two identical dice have 21 configurations? Where are those additional configurations coming from if there are only 12 possible values in the pair of dice?
Re: How the Many-Worlds Theory of Hugh Everett Split the Universe
#78Earlier quoted context omitted.
Haven't we tested precisly this? The fact that we observe interference patterns shows that the wavefunctions are real. As far as I can tell, Copenhagen posits that there is a scale at which wave functions stop being real, and instead collapse down to a single "macroscopic" state. Convieniently, this scale happens to be around the scale where our experiments stop being able to test for it in practice. Put another way,…
> The fact that we observe interference patterns shows that the wavefunctions are real. well, not quite - remember that what we actually observe for a given particular event is something that looks like particle that is localized in space. If you're referring to the double slit experiment, the interference pattern emerges as a property of the whole collection of individual photon strikes. Yes, you need to use the wav…
If we put the sensor in the slits themselves, what we would observe is individual photons passing through one slit or the other. What the double slit experiment shows is that there is still something of a wavefunction (whatever that actually is) at the moment the photons pass the slit, because that is how we get the interference pattern.
As before when we observe the photons, we see them as single discreet particles. However, in principle this seems to be the same situation as when we detect photons passing through a slit.
Re: How the Many-Worlds Theory of Hugh Everett Split the Universe
#79Earlier quoted context omitted.
> The fact that we observe interference patterns shows that the wavefunctions are real. well, not quite - remember that what we actually observe for a given particular event is something that looks like particle that is localized in space. If you're referring to the double slit experiment, the interference pattern emerges as a property of the whole collection of individual photon strikes. Yes, you need to use the wav…
If we put the sensor in the slits themselves, what we would observe is individual photons passing through one slit or the other. What the double slit experiment shows is that there is still something of a wavefunction (whatever that actually is) at the moment the photons pass the slit, because that is how we get the interference pattern. As before when we observe the photons, we see them as single discreet particles.…
Right, but in that case we never observe the wavefunction, the quantum state of the particle, or the particle interacting with itself.
In that sense, the wavefunction predicts the outcome but it does not have to "real". It is real in Pilot Wave theory, but it could simply be a mathematical or calculational tool .
In either case, you are right that one has to use it get the right result.
Let me ask you a similar question. Are virtual particles, as described with Feynman diagrams, real?
Re: How the Many-Worlds Theory of Hugh Everett Split the Universe
#80Earlier quoted context omitted.
Haven't we tested precisly this? The fact that we observe interference patterns shows that the wavefunctions are real. As far as I can tell, Copenhagen posits that there is a scale at which wave functions stop being real, and instead collapse down to a single "macroscopic" state. Convieniently, this scale happens to be around the scale where our experiments stop being able to test for it in practice. Put another way,…
> The fact that we observe interference patterns shows that the wavefunctions are real. well, not quite - remember that what we actually observe for a given particular event is something that looks like particle that is localized in space. If you're referring to the double slit experiment, the interference pattern emerges as a property of the whole collection of individual photon strikes. Yes, you need to use the wav…
Non-physicist perspective, if I’m out of line, please say so.
It seems silly to expect that the wavefunctuon is “real” just like it is silly to assume that the gravitational field is “real” or inches are “real”. They are mathematical constructions we use to make predictions about what we see. Just because the predictions are good doesn’t make the mathematical formalism real.
As a contrived example, imagine an advanced AI program running on Linux. The AI develops all sorts of models and makes very accurate predictions about what will happen in user space when it calls fopen or pipes data from /dev/urandom. But no matter how well it models the output of /dev/urandom, it will never know that the reason why the data seems random is because the kernel is generating it from a camera pointed at a lava lamp. Even if the AI was smart enough to invent models for the lava lamp and the camera optics, etc, this model wouldn’t be real, it’s still some bits in memory /describing/ what is going on outside of the AIs immediate experience.