U.Delft Quantum Results - Is the explanation parsimonious?

[ndvcxk123]

TL;DR Summary

u-delft experiment: Would Occam's razor not reject the explanation "the photons are connected" in lieu of "Well, there may be hyperfast particles we don't know yet". (They are just as invisible as a connection, right ? ) (I'm in biology..thx for clarifying)

Thx !

 

[George Jones]

Summary:: u-delft experiment

What experiment? Please give a reference.

 

[DrChinese]

I'm guessing this experiment (since it was performed at that university campus):

https://arxiv.org/abs/1508.05949

 

[DrChinese]

Summary:: u-delft experiment: Would Occam's razor not reject the explanation "the photons are connected" in lieu of "Well, there may be hyperfast particles we don't know yet". (They are just as invisible as a connection, right ? ) (I'm in biology..thx for clarifying)

This experiment is a great one, but you are jumping to the middle of the story and skipping over many key elements. To start with, there really is no way to apply Occam's razor as a way to convince others. Simple is subjective. And what you call "simpler" is not necessarily simple at all. If there are "hyperfast particles" that would imply substantial new physics; and not surprisingly, there has been plenty of study along those lines. But none (so far) leading to anything useful.

But the issue around entanglement - which demonstrates the phenomena of "quantum nonlocality" - is that quantum theory accounts for it without the need for new particles. However, the theory does not include any specific mechanism for what is occurring. That is supplied by the so-called "interpretations" of quantum mechanics. There are a number of these, including the Many Worlds Interpretation (MWI) and Bohmian Mechanics (BM). There is no generally accepted interpretation, and in fact many believe no interpretation is needed. There is a sub forum of Quantum Mechanics here which is devoted to Interpretations.

https://www.physicsforums.com/forums/quantum-interpretations-and-foundations.292/

Cheers!

 

[Nugatory]

There's some personal taste involved in just about any application of Occam's razor. For example, "evil spirits at work" is a parsimonious - just one assumption needed! - explanation for an otherwise unexplained illness, but not one that will appeal to someone with a background in biology.

"There may be hyperfast particles we don't know yet" is a similarly minimal explanation of entanglement correlations, but is even less satisfying. The assumption that evil spirits influence some aspects of our health does not necessarily conflict with biological explanations of other aspects; the hypothesis that hyperfast particles are involved in entanglement conflicts with vast swathes of modern physics.

 

[Nugatory]

However, the theory does not include any specific mechanism for what is occurring. That is supplied by the so-called "interpretations" of quantum mechanics. There are a number of these

There is, of course, the possibility that @ndvcxk123 finds all of them unsatisfactory in one way or another - that's a natural and widely shared reaction.

If so, Occam's razor suggests a way out: Drop the unnecessary and unsupportable assumption that the universe has to behave according to laws that conform to our intuition about how it ought to behave.

 

[vanhees71]

Occam's razor tells (at least a majority) of physicists to simply use the well-established quantum electrodynamics to describe photons. It describes correctly all the highly precise observations in HEP physics and quantum optics very well. There's no need for hypthetical "hyperfast particles" at all.

 

[ndvcxk123]

This experiment is a great one, but you are jumping to the middle of the story and skipping over many key elements. To start with, there really is no way to apply Occam's razor as a way to convince others. Simple is subjective. And what you call "simpler" is not necessarily simple at all. If there are "hyperfast particles" that would imply substantial new physics; and not surprisingly, there has been plenty of study along those lines. But none (so far) leading to anything useful.

But the issue around entanglement - which demonstrates the phenomena of "quantum nonlocality" - is that quantum theory accounts for it without the need for new particles. However, the theory does not include any specific mechanism for what is occurring. That is supplied by the so-called "interpretations" of quantum mechanics. There are a number of these, including the Many Worlds Interpretation (MWI) and Bohmian Mechanics (BM). There is no generally accepted interpretation, and in fact many believe no interpretation is needed. There is a sub forum of Quantum Mechanics here which is devoted to Interpretations.

https://www.physicsforums.com/forums/quantum-interpretations-and-foundations.292/

Cheers!

First, I'm honored by the granular replies to a stranger, and realize that biologists are viewed by physicists as "boys looking at large worms", at least scale-wise. (Ok, we are). So, w. humility, here a summary:
1) Occ. Rz, fullfilled bec. no explanation needed ! Nice, but does this not equate a) ceasing investigation w. b) providing a mechanism ? A decision not to look further is not a description of a mechanism.
2.) "Hyperfast particles" imply new physics. But the Delft-experiment establishes the quant. effect for sure, (i.e. meas. error excluded now) - so you've already overturned physics bec. Entanglement reaction is faster than light. The hyperfastness is already established by the experiment, the quest. is only if a particle-assumption is more parsimonious than the others, ergo:
3) MWI (which is supported by Deutsch from double-slit also ) - my quest. here is similar: Do you really need the additional worlds ? Why not say "When we shoot an individual photon, it (clearly) seems to collide w. unseen ones. - Thus, by shooting a photon, it interscts w. oth. unseen photons. I think one has to STOP there, the evidence does not go beyond this. So the term "entanglement" has a similar quality, it presupposes a connection in lieu of "cause and effect". Everything prior has been cause and effect based. New particles are constantly being discovered, and they were there, we did not know it. (I know this is a boring explanation).
4) Bohmian, cannot comment, not read yet.
5) A note on Gerlach: Who has been at a state fair + at the arcade moved the stick magnet through the curved rails, w. pull from both rails ? If you lay out the Gerlach experim. to a person who has just done this, and ask: Will the particles form Gauss distrib. or either be sucked left or right, w. nothing in middle ? They will say, yep, either left or right. And if we alter Gerlach, pulling the magnets farther and farther apart, equidistantly, in the end, the alu. will fly through. Some outlyers will be sucked left and right. So, Gerlach is not persuasive to me, as proof of a quantum-forced choice - but I have not played with the Gerlach applet as I don't have the
java engine installed.
6) The other point I don't get in reviews of the experiment is the extrapolation over much larger distances.
Thanks all, and yes you may mock me: 1) Stem cells 20+ years, not in clinic, 2) CRISPR - off-target effects, 3) anti-VEGF " we defeated cancer" (oh no, there other pathways for onco-vasculogenesis-damn!) 4) DNA! we know you now (oh, often silent) 5) RNA the transcriptome-ha now we have it! (Oh, lots of transcripts not corresponding to prot.expression, damn). So I self-mocked. You guys are working on the true mysteries...Thx

So my conclusion is that the term "entanglement" is tactically useful to enhance interest in physics, and maybe also bec. mysteries offer hope in the same sense as a future "heaven". I realize that the explanatory search has taken decades and decades, and that at one point, the community said, we have to abandon locality bec. there simply is no other explanation. Still, it is a huge jump !

 

[DrChinese]

First, I'm honored by the granular replies to a stranger, and realize that biologists are viewed by physicists as "boys looking at large worms", at least scale-wise. (Ok, we are). So, w. humility, here a summary:
1) Occ. Rz, fullfilled bec. no explanation needed ! Nice, but does this not equate a) ceasing investigation w. b) providing a mechanism ? A decision not to look further is not a description of a mechanism.
2.) "Hyperfast particles" imply new physics. But the Delft-experiment establishes the quant. effect for sure, (i.e. meas. error excluded now) - so you've already overturned physics bec. Entanglement reaction is faster than light. The hyperfastness is already established by the experiment, the quest. is only if a particle-assumption is more parsimonious than the others, ergo:
3) MWI (which is supported by Deutsch from double-slit also ) - my quest. here is similar: Do you really need the additional worlds ? Why not say "When we shoot an individual photon, it (clearly) seems to collide w. unseen ones. - Thus, by shooting a photon, it interscts w. oth. unseen photons. I think one has to STOP there, the evidence does not go beyond this. So the term "entanglement" has a similar quality, it presupposes a connection in lieu of "cause and effect". Everything prior has been cause and effect based. New particles are constantly being discovered, and they were there, we did not know it. (I know this is a boring explanation).
4) Bohmian, cannot comment, not read yet.
5) A note on Gerlach: Who has been at a state fair + at the arcade moved the stick magnet through the curved rails, w. pull from both rails ? If you lay out the Gerlach experim. to a person who has just done this, and ask: Will the particles form Gauss distrib. or either be sucked left or right, w. nothing in middle ? They will say, yep, either left or right. And if we alter Gerlach, pulling the magnets farther and farther apart, equidistantly, in the end, the alu. will fly through. Some outlyers will be sucked left and right. So, Gerlach is not persuasive to me, as proof of a quantum-forced choice - but I have not played with the Gerlach applet as I don't have the
java engine installed.
6) The other point I don't get in reviews of the experiment is the extrapolation over much larger distances.
Thanks all, and yes you may mock me: 1) Stem cells 20+ years, not in clinic, 2) CRISPR - off-target effects, 3) anti-VEGF " we defeated cancer" (oh no, there other pathways for onco-vasculogenesis-damn!) 4) DNA! we know you now (oh, often silent) 5) RNA the transcriptome-ha now we have it! (Oh, lots of transcripts not corresponding to prot.expression, damn). So I self-mocked. You guys are working on the true mysteries...Thx

Biologist or not, we all seek answers... I won't answer all of your questions, but I have a few comments that may help.

1. Entanglement is not new physics. It had appeared in the early 1930's, but there was no good way to test at that time. And no one knew what to look for. It took Bohm, Bell and Aspect (among many others) to get us to a place in the 1980's where understanding began to grow.

There is plenty of work going on to better understand entanglement. Literally hundreds of papers a month are written, and every aspect of entanglement is being probed. However, the effect has been demonstrated thousands of times, and every single experiment supports the standard quantum model. (The one that is nearly 100 years old.) As already mentioned, you must look at the interpretations to understand the search for mechanisms. This is quite a complex area, and without understanding *why* there are interpretations, you won't be able to go very far. Keep in mind that all interpretations essentially make the same experimental predictions (otherwise they would be falsified).

2. No, imagining "hyperfast particles" is no more enlightening than saying there are dragons and witches. You are free to imagine your own solutions, of course. But again, without understanding more about entanglement, you won't see the obvious problems. For example, which way do your hyperfast particles travel? Since time ordering is not a factor in the quantum predictions, it is not clear if they travel from the past to the future or from the future to the past. Turns out the ordering is by assumption only! And the idea that there is already "hyperfastness" established is wrong for a number of reasons. What you call "hyperfastness" is called "quantum non-locality" in the literature. But that does not mean anything exceeds the speed of light c. It might, or it might not, there are plenty of good reasons for either view. Again, each person has their own favored interpretation (or are agnostic).

Further: there is no requirement that particles interact to become entangled. So where do the hyperfast particles even fit it? In fact, there is no requirement that entangled particles even exist at the same time. Strange, but true.

3. MWI: do your best to knock this interpretation, but the reason it exists is because it explains things other interpretations cannot. Again: Occam is strictly in the eye of the beholder as I already mentioned. You will NOT be able to convince others that your favored interpretation is better because of Occam's Razor. You are free to try... but MWI has gained popularity steadily since its introduction in the late 1950's. (FYI I do not push MWI as my favored interpretation.)

4. Bohmian Mechanics is where the hyperfast (actually instantaneous) model is most studied.

5. And again, looking at SG experiments, you are looking at the tip of an iceberg. There is so much more to understand in this area, it really doesn't make sense to dismiss the "magic" until you catch up a bit. I would recommend either filling in a few of your gaps, or focusing on one area (such as entanglement) before you dismiss decades of work.

Please keep in mind that existing theory is essentially "perfect" while not being able to answer certain kinds of questions. In other words: the predictions of QM are accurate, which is the desired attribute of a useful theory. Everyone is open to something new, but the requirements of a quantum theory are very exacting. Therefore, improvements must make the same predictions as existing theory, but be able to explain something extra not currently explained.

6. Not really sure I follow you here about "extrapolation over much larger distances". Can you explain what you are referring to? Bell tests have been performed over quite large distances, and quantum effects have been observed across many light years.

Cheers!

 

[Nugatory]

Hyperfast particles" imply new physics. But the Delft-experiment establishes the quant. effect for sure, (i.e. meas. error excluded now) - so you've already overturned physics

The Delft experiment does no such thing. It is another confirmation of the quantum mechanical theory that was developed almost a century ago, in the mid-1920s, and is best thought of as a successful exercise in dotting the I’s and crossing the T’s. The results are exactly what everyone expected on the basis of accepted physics - had they been different that would have meant some serious overturning, but that didn’t happen and no one was surprised.

Entanglement reaction is faster than light. The hyperfastness is already established by the experiment

That is not what the experiment established. The experiment further confirmed certain predictions of quantum mechanics by eliminating some of the “loopholes” that made previous experiments extremely convincing but not absolutely conclusive.

We also have Bell’s theorem, which shows that no theory that is both “local” and “realistic” (these terms have more precise definitions, but informally only theories that are both local and realistic conform to our common-sense prejudices about how the world ought to work) can make these predictions. Locality and realism together imply an inequality (Bell’s inequality); quantum mechanics predicts that this inequality will be violated; a half-century of experiments shows that the quantum mechanical prediction is correct; therefore our common-sense prejudices are wrong.

It is a huge leap from there to the conclusion that “hyperfast particles” are the best explanation, or even a slightly good one.

So my conclusion is that the term "entanglement" is tactically useful to enhance interest in physics

The term has a precise mathematical definition: there is an algebraic property of some wave functions, and we say that systems whose wave functions have this property are entangled.

A good layman-friendly introduction to the entire history is Louisa Gilder’s book “The Age of Entanglement“.

 

[vanhees71]

Well, I think as long as quantum theory stands all the high-precision tests it stands for 95 years now, there is no need to find some "mechanism behind entanglement". QT just describes all empirical results with utmost precision. You cannot hope for more "explanation" or "mechanism" from a physical theory than that. In its relativistic form as local, microcausal relativistic quantum field theories the theory is also fully compatible with the (special) relativistic spacetime model and causality. All "mechanism" there is, is thus quantum theory!

 

[atyy]

Summary:: u-delft experiment: Would Occam's razor not reject the explanation "the photons are connected" in lieu of "Well, there may be hyperfast particles we don't know yet". (They are just as invisible as a connection, right ? ) (I'm in biology..thx for clarifying)

The important point about hyperfast particles and other superluminal mechanisms is that if quantum mechanics is correct, the superluminal mechanisms cannot be used for superluminal transmission of information.

So quantum mechanics does say that if we discuss mechanisms, then superluminal mechanisms or something more exotic is required. But if we discuss information transmission, the quantum mechanics also says that there is no superluminal information transmission.

In the orthodox Copenhagen-style interpretation of quantum mechanics, we are agnostic as to what mechanisms are involved, since we do not need to know the mechanisms to predict the results of measurements.

 

[vanhees71]

I'd say the lesson, which is most difficult for humans trained in classical physics is to accept, that there are no "mechanisms" (aka hidden variables) behind the observed randomness of Nature. There's no way to predict when a individual Ra nucleus decays. The only thing we know is it's average lifetime. According to quantum theory there's no hidden variable, which determines the precise time when the individual nucleus decays, if we only knew its value, and so far we haven't found any deterministic hidden-variable model which is in accordance with the observationally successful predictions of QT. So the conclusion is that, at least based on the best theory we have, which is QT, the lifetime of an individual Ra nucleus objectively is indetermined. All that can be known is the probability that the nucleus has been survived till time $t$, given it has been there at time $t=0$. It's approximately $\exp(-t/\tau)$ (for a nucleus at rest and with $\tau$ it's average lifetime), according to the well-known law of radioactive decay (it's for sure an approximation, because due to unitarity there cannot be strictly valid exponential decay laws, but that's another story).