History on Many Worlds Theory

This new paper gives some history and arguments in favor of many-worlds:

Revolutionizing Quantum Mechanics: The Birth and Evolution of the Many-Worlds Interpretation

Arnub Ghosh

The Many-worlds Interpretation (MWI) of quantum mechanics has captivated physicists and philosophers alike since its inception in the mid-20th century. This paper explores the historical roots, evolution, and implications of the MWI within the context of quantum theory. ...

In reflecting on the significance of studying the historical development of quantum interpretations, it becomes evident that the MWI represents more than just a theoretical framework—it embodies a paradigm shift in our understanding of the quantum world and its implications for the nature of reality. ... Moving forward, further research and exploration in this area hold immense potential for advancing our knowledge of quantum mechanics and its applications.

Okay, you know it is garbage when it pushes revolutions and paradigm shifts, but cannot find any actual utility to the theory.

A big problem is probability:

Moreover, the MWI has led to new insights into the nature of probability in quantum mechanics. In the MWI, probabilities arise from the relative frequencies of different outcomes across multiple branches of the multiverse, rather than from inherent randomness or observer-dependent collapses of the wavefunction. This perspective offers a coherent and objective interpretation of probability in quantum mechanics, resolving longstanding debates about the nature of quantum uncertainty. ...

Furthermore, the MWI has implications for our understanding of probability and randomness. In the MWI, probabilities arise from the relative frequencies of different outcomes across multiple branches of the multiverse, rather than from inherent randomness or observer-dependent collapses of the wavefunction. This perspective offers a coherent and objective interpretation of probability in quantum mechanics, resolving longstanding debates about the nature of quantum uncertainty. However, it also challenges traditional views of probability as a measure of uncertainty or ignorance, suggesting that probabilities are ontologically real and arise from the fundamental structure of the multiverse.

(This is repetitive.) Yes, you might think that MWI gets probabilities from comparing outcomes across branches, but no one has ever gotten this to work. It is a myth. You cannot count the branches, or calculate probabilities of outcomes, or do anything objectively. It is all a big sham.

The people who pursue many-worlds do not even believe in probabilities. If pressed, they will admit that some things seem more probable than others, but they say it is all an illusion. Some subscribe to crazy arguments that Born's rule seems more natural than other rules, but they have no good explanation for why probability works at all.

If the weather man says there is an 80% chance of rain tomorrow, then he means that his data has resulted in rain 80% of the time in the past. Once it rains, you can discard the possibility of a sunny day.

But the MWI fans reject this. They refuse to say that it will rain in 80% of the branches. And if it does rain, they refuse to reject the sunny day, because they argue that it is sunny in another part of the wave function.

Go ahead and read the article, and tell me if you find one reason to accept that MWI nonsense.

Free Will in the Block Universe

Some say that there is no free will because of the way relativity uses time as the fourth dimension.

The philsophical questions about free will go back to the ancient Greeks. Modern science has not settled those questions. The questions are certainly not settled by just declaring that time is a coordinate.

SciAm reports:

As troubling as quantum mechanics (or at least certain versions of it) may be for the idea of free will, relativity—the other pillar of modern physics—isn’t off the hook. Many theorists think of relativity as describing a universe in which past, present and future are all equally real: a static cosmos that just sits there like a big block of spacetime (sometimes called the “block universe”). It’s not that time disappears in this picture—but it no longer “passes” or “flows.” (As Albert Einstein famously put it, the passage of time is a “stubbornly persistent illusion.”) Conceptually speaking, the strongly deterministic quantum universe and the block universe of relativity may not be so far apart. The quantum version can be thought of as “a kind of enriched block universe,” says Alastair Wilson, a philosopher of science at the University of Leeds in England. “Imagine taking a block universe and adding an extra dimension to it—the dimension of possibility.” ...

Even without relativity, you could use a time coordinate to make a block universe. You can use any coordinates you want. Choosing some coordinates cannot possibly say anything about free will.

Many-worlds theory takes this to the next step, if you put all those many worlds in a big block multiverse.

While physicists continue to debate the idea of strong determinism, Emily Adlam, a philosopher of physics at Chapman University, agrees with Chen that it appears to present more of a threat to free will than traditional determinism, particularly because of its ties to the Everettian multiverse. “In a standard deterministic picture, sure, everything that happens was determined from the past—but your mind was a key part of the causal process by which future events get realized,” Adlam says. “So in some meaningful sense, future events—even though they were predetermined—were mediated through processes that you identify with yourself.” But in the Everettian picture, she says, it’s harder to see where decision-making would fit in. “If you always make every possible decision, that does seem to severely undermine the sense in which you are exercising any meaningful kind of choice,” she says. “So in that sense, you do seem worse off than in the standard picture, where one outcome occurs and you play a role in bringing it about.”

It goes on to say that this is controversial, as there are compatibilists who can rationalize belief in free will no matter what soft of determinism there is.

There is no mention of anyone who believes in true free will, now called libertarian free will.

The whole point of the article is to say that many-worlds theory presents a new argument against free will. Since all choices happen in parallel worlds simultaneously, then all choice possibilities are real, and humans cannot make any free will choices. That are all illusions.

This is absurd.

I wonder what Plato and Aristotle would say if we could go back in time, and tell them about our progress. We could tell them about rockets, cars, lasers, electronics, and drugs, and they would be impressed.

And then we would tell them that our best and finest theory of matter, quantum mechanics, has been interpreted to say that there is no free will, because we can imagine parallel universes where alternative decisions are made. They would rightfully conclude that we have made no progress in philosophy at all, and even regressed to some very silly ideas.

There is Nothing Non-entangled in QM

Supposedly entanglement is the most important thing in quantum mechanics (QM). It is said to be the key feature that distinguishes QM from classical mechanics.

But what is it?

New paper:

Everything is Entangled in Quantum Mechanics: Are the Orthodox Measures Physically Meaningful?

Christian de Ronde, Raimundo Fernandez Moujan, Cesar Massri

Even though quantum entanglement is today's most essential concept within the new technological era of quantum information processing, we do not only lack a consistent definition of this kernel notion, we are also far from understanding its physical meaning [35]. These failures have lead to many problems when attempting to provide a consistent measure or quantification of entanglement. I

According to a lot of modern scholars, entanglement is a resource that can be exploited to give secure communication and super-Turing computability.

The paper discuss various definitions in the literature and concludes:

We have shown how entanglement, as the unitary multiscreen effect of a single power, is an irreducible aspect of the operational content of the theory of quanta. The theory talks about powers of action each one them producing a multiscreen (non-local) effect that can be observed in the lab. Consequently, there is nothing non-entangled in QM. There is no meaningful distinction between something that is entangled and something that is not entangled within the theory of quanta. The attempt of quantifying or measuring the level of entanglement becomes meaningless.

I think that entanglement is not something real. It is an artifact of how QM works, but there is no way to objectively say whether a particle is entangled or not. So we should not talk about entanglement as if it is some mysterious resource.

Maybe I will be proved wrong by some quantum computer that uses entanglement to break RSA or some other calculation that cannot be done otherwise. Then I will have to admit that entanglement is real and useful. But nothing like that has ever been done.

Sean M. Carroll tries to explain entanglement in a recent podcast:

I 0:20 think you know entanglement arises 0:22 directly from that statement we made 0:23 long ago that when you have a Quantum 0:25 system you do not have separate wave 0:27 functions for each part of it you only 0:29 have one wave function for the whole 0:30 thing and the job of the wave function 0:33 is to make predictions for observational 0:35 outcomes so if that's all true then it 0:38 could be the case that if you predict 0:41 the outcome for one thing and another 0:43 thing particle a and particle B there 0:46 might be correlations or connections 0:48 between those measurement outcomes so I 0:50 don't know what I'm going to see when I 0:52 ask what is the spin of particle a and I 0:54 don't know what I'm going to see when I 0:56 ask what is the spin of particle B but I 0:58 know they're going to be opposite so 1:00 then that's entanglement and it tells me 1:02 were I to measure particle a I have no 1:04 idea what I'm going to observe but as 1:06 soon as I do I know what the outcome is 1:08 for particle B and this bugs people 1:11 because how does particle B know what 1:13 its outcome is supposed to be it could 1:15 be light years away

If this is the definition of entanglement, then there is nothing quantum mechanical about it. Classical physics shows the same phenomenon.

If split a classical system with angular momentum zero, separate the halves, and measure the angular momentum of one half, then the other half will have the opposite angular momentum. Just like how Carroll described QM.

When asked for more explanation, he says that he prefers the Everett many-worlds interpretation. However he admits that no one knows whether the effect of a measurement propagates at the speed of light or less in the universal wave function, or propagates instantaneously.

What? I thought that the whole point of Everett was to clarify what happens quantum mechanically when a measurement takes place. But if he cannot tell how the result propagates, then I do not see how it can tell me anything.

See also this podcast, where he starts by saying the Everestt theory is the most straightforwad interpretation of the Schroedinger equation, but it requires splittings into parallel worlds and we do not know what a world is. We also do not know if the wave function is real. Later, at 45:30 he says, "I mean the real answer there is I don't think about all those other worlds, that much again the worlds are a prediction of the theory they're not what the theory is fundamentally about."

Carroll goes on to explain the Bell tests:

also in the 1960s John Bell proved his 6:17 theorems he proved theorems about the 6:20 different predictions between a local 6:22 Theory and a non-local theory like 6:24 quantum mechanics and that made it an 6:27 experimentally accessible question so 6:29 people did the experiment and they just 6:31 won the Nobel Prize a couple years ago 6:33 so physicists are very interested now 6:35 because there's an experiment you can do 6:37 of course the experimental result was 6:38 exactly what schrodinger would have 6:40 predicted back in the 1920s it didn't 6:42 change our idea of quantum mechanics but 6:44 as long as you can do an experiment 6:45 they're happy having said that because 6:48 physicists have ignored the foundations 6:49 of quantum mechanics for so long even 6:52 the Nobel Prize press release botched it 6:55 they gave the wrong explanation for what 6:57 was going on because they didn't really 6:59 understand what they just give the Nobel 7:00 Prize

Again, this is startlingly foolish. He correctly says that the prize-winning experiments just confirmed what quantum mechanics would have predicted in the 1920s, and did not change our idea of quantum mechanics.

So how did the Nobel press release botch it? It certainly did not say that the experiment changed our view of QM. That would have been big news. See my earlier post for more details.

Carroll's real gripe is that he wants to fund more research in the foundations of QM, and the Nobel committee refused to acknowledge that the experiments left unsettled issued. In particular, he wants to push many-worlds theory, but it gets no Nobel endorsement. The Nobel committee correctly said that the experiments confirmed what everyone thought for many decades.

Einstein's Futile Search for Unified Field Theory

Sabine Hossenfelder posted her latest video:

Einstein’s Other Theory of Everything

Einstein completed his theory of general relativity in 1915 when he was 37 years old. What did he do for the remaining 40 years of his life? He continued developing his masterwork of course! Feeling that his theory was incomplete, Einstein pursued a unified field theory. Though he ultimately failed, the ideas he came up with were quite interesting. I have read a lot of old Einstein papers in the past weeks and here is my summary of what I believe he tried to do.

She insists on pronouncing his name INE-shtine. Maybe Germans pronounce it that way, but not Americans.

She summarizes Einstein's foolish and misguided unified field theories. If he did not already have a fancy reputation, this would be considered crackpot work.

She also mentions the more successful Kaluza–Klein theory:

In physics, Kaluza–Klein theory (KK theory) is a classical unified field theory of gravitation and electromagnetism built around the idea of a fifth dimension beyond the common 4D of space and time and considered an important precursor to string theory. In their setup, the vacuum has the usual 3 dimensions of space and one dimension of time but with another microscopic extra spatial dimension in the shape of a tiny circle. Gunnar Nordström had an earlier, similar idea.

This is also described as a failure. She says you need supersymmetry to make it work, but that has been rejected.

That theory is a minor variant of a 1918 H. Weyl proposal to unify gravity (general relativity) and electromagnetism. That was promptly attacked by Einstein, and mostly forgotten.

There the story ends. But not really. Einstein's ideas were, in fact, worthless, and led several generations of physicists astray. I wrote a whole book about it.

But Weyl's idea was essentially correct. In the modern Standard Model, that everyone accepts, there is an extra tiny circle at every spacetime point (event) to account for electromagnetism. In modern lingo, it is a circle bundle over a spacetime manifold. Gravity is a connection on the tangent bundle, and electromagnetism is a connection on the circle bundle. In both cases, the field is the curvature. It is the simplest and most natural relativistic theory.

Physicists studied Weyl and Kaluza-Klein for decades, without ever figuring out that they were just adding extra terms that ruined the theory. I guess they wanted to unify the gravity with the electromagnetism by hypothesizing some interactions, but that was just foolishness.

If Weyl were really smart, he would have conjectured using other Lie groups form the strong and weak interactions, alongside the circle for electromagnetism. Then we could have had the Standard Model, before quantization, about 50 years before we did.

One of the Lessons of the Standard Model is that all four forces (gravity, electromagnetism, weak, and strong) all have the same math structure (field strength is curvature of a bundle connection), but the force are essentially orthogonal. They do not have much to do with each other. There is some twisting between the weak and electromagnetism, but that's all. Many people thought that they would be unified like electricity and magnetism, where you cannot study one without the other.

Gravity is a Force

Physicists are sharply divided over whether gravity is a force. Oh, they refer to it as a force all the time, such as saying it is one of the four fundamental forces, but then say it is a fictitious force.

The excellent video channel Veritasium has explanation of Why Gravity is NOT a Force.

It is like the people who say that centrifugal force is not a force, but centripetal forces is.

Gravity has been considered a force since Newton in the 1600s, so the opposite view requires explanation.

Actually, it is not so clear that Newton believed that gravity was a force. He was very much against action-at-a-distance:

Newton famously struggled to find out the cause of gravity.^[12] In a letter to Bentley, dated January 17 1692/3, he said:

You sometimes speak of Gravity as essential and inherent to Matter. Pray do not ascribe that Notion to me, for the Cause of Gravity is what I do not pretend to know, and therefore would take more Time to consider it. (Cohen 1978, p. 298)

In a subsequent letter to Bentley, dated February 25, 1692/3, he added:

It is inconceivable that inanimate Matter should, without the Mediation of something else, which is not material, operate upon, and affect other matter without mutual Contact…That Gravity should be innate, inherent and essential to Matter, so that one body may act upon another at a distance thro’ a Vacuum, without the Mediation of any thing else, by and through which their Action and Force may be conveyed from one to another, is to me so great an Absurdity that I believe no Man who has in philosophical Matters a competent Faculty of thinking can ever fall into it. Gravity must be caused by an Agent acting constantly according to certain laws; but whether this Agent be material or immaterial, I have left to the Consideration of my readers. (Cohen 1978, pp. 302-3)

Aristotle also denied that gravity was a force.

The Aristotelian explanation of gravity is that all bodies move toward their natural place.

There are two arguments that gravity is not a force. One says that you do not feel gravity in free fall. You feel it when you stand on the ground, but you are really feeling the force of the ground pushing you up.

The second is that general relativity teaches that gravity is just curvature of spacetime, not a force. This is a variation of Aristotle's argument.

A typical explanation:

“The one sentence statement of general relativity is that ‘gravity is the curvature of spacetime,’” explains Dr. Sean Carroll, assistant professor of physics at the University of Chicago. “Really, the differences come in understanding what that sentence means.”

Carroll says that origin of the theory of general relativity dates to 1905, when scientists, notably including Albert Einstein, realized that space and time are related characteristics of a four-dimensional existence. ...

However, within this new 4-D framework, says Carroll, Einstein could not understand gravity, and how it worked in spacetime. He decided that rather than being a force, like electromagnetism, gravity must be a property: a geometric curvature.

This stuff about Einstein believing that gravity is geometrical curvature is a modern invention. Yes, he used the equations for curvature, but did not subscribe to the geometric interpretation that is popular today.

General relativity differs very slightly from Newtonian gravity. It is silly to say one is a force and the other not. They are essentially the same.

My biggest quibble is with those who say electromagnetism is a force, but gravity is not. In modern physics, all of the four fundamental forces have geometrical interpretations, where the field strength is given by curvature. Test particles follow curvature, in all cases. Here is a recent paper explaining it. So if gravitational forces are fictitious because particles are just following curvature, then nothing else is a force either.

Those who deny that gravity is a force sometimes go one step farther, and deny causality. Eg, from the Stanford Encyclopedia:

Causation in Physics

What role, if any, do causal notions play in physics? On the one hand, it might appear intuitively obvious that physics aims to provide us with causal knowledge of the world and that causal claims are an integral part of physics. On the other hand, there is an influential philosophical tradition, dating back to Ernst Mach and to Bertrand Russell’s extremely influential article “On the Notion of Cause” (1912), denying the applicability or at least the usefulness of causal notions in physics. While this tradition is perhaps not as dominant today than it once was, there continues to be a lively and active philosophical debate on whether causal notions can play a legitimate role in physics and, if yes, what role that might be.

One part of this is that if you believe in determinism and the block universe, then the Big Bang caused everything, and nothing else had any influence.

I take the view that we have forces and causes. I am all in favor of the geometrical interpretation, but not to deny forces and causes.

While I think most physicists take a geometrical view, here is a new oddball paper:

A Puzzle About General Covariance and Gauge

Eleanor March, James Owen Weatherall

We consider two simple criteria for when a physical theory should be said to be "generally covariant", and we argue that these criteria are not met by Yang-Mills theory, even on geometric formulations of that theory. The reason, we show, is that the bundles encountered in Yang-Mills theory are not natural bundles; instead, they are gauge-natural.

Of course Yang-Mill (gauge) theories are generally convariant, as the theory is independent of any particular coordinates. If you change coordinates, then the equations of motion transform as you expect from vectors and tensors.

The paper makes the trivial point that if you change the coordinates, that does not necessarily tell you how to change the gauge. Yang-Mill theories are covariant over a change in coordinates and gauge.

These confusing arguments only obscure the fact that gravity, electromagnetism, strong, and weak forces all use the same geometrical constructions. Just the bundles are different. Gravity uses the tangent bundle on spacetime, while the other forces use U(1), SU(3), and SU(2) bundles. They are all covariant.

The Wikipedia article on general covariance says that Einstein popularized the term, but did not use it precisely. So I guess that is why some might think that it applies to general relativity, but not to other bundles.

Update: Here is a new paper explaining general covariance.

The free field then couples to the gauge field, producing an interaction term in the Lagrangian that is gauge-invariant. Neither the original electron field, nor the gauge field are gauge invariant, but the way they appear in the Lagrangian is through a gauge invariant term. One then proceeds to define gauge invariant things like the tensor field 𝐅:=d⁢𝐀 and claims that the physics of the theory is contained only in those objects.

Likewise, diffeomorphisms in GR are regarded as extra, unphysical degrees of freedom: the physics must be contained only in gauge-invariant quantities. This is in flagrant contrast with what experience tells us: in ‘real life’ things are constrained to fixed frames of reference, and one can measure ‘gauge-variant’ [8] quantities, such as the energy, proper time, the electric field, and so on.

Wilczek says Falling Cats have Free Will

Physicist Frank Wilczek is famous for helping explain the short range nature of the strong force, and now he wrote a strange paper on cats. No, not Schroedinger cats.

Free Will and Falling Cats

If we consider a cat to be an isolated mechanical system governed by T-invariant mechanics, then its ability to land on its feet after being released from rest is incomprehensible. It is more appropriate to treat the cat as a creature that can change its shape in order to accomplish a purpose. Within that framework we can construct a useful and informative of the observed motion. One can learn from this example.

He seems to be saying that it is impossible for a falling cat to land on its feet, unless it has free will.

He proves it is impossible, but then says cats have a loophole because "They can readily and selectively consume stored energy, notably by converting ATP into ADP, empowering mechanical motion accompanied by radiation of heat."

This is bizarre. The physics of falling cats is well-understood, and does not require free will or ATP or heat or anything like that. See A simple model for the falling cat problem. There is even a Wikipedia article on it.

The paradox is that the cat falls with zero angular momentum, a conserved quantity, and it is hard to see how it can get its feet down without some angular momentum. But as the above paper explains, the cat can twist its body without any net angular momentum.

Wilczek has some philosophical comments that went over my head, so maybe I am not fully appreciating his paper. After all, he has a Nobel Prize and I don't. What am I missing? He does cite a book on "Falling Felines and Fundamental Physics", so he must know that this is understood.

Carroll Eulogy for Dan Dennett

Physicist Sean M. Carroll released his latest AMA podcast. He starts with a eulogy.

Dan Dennett you know was not only a hugely important 1:02 philosopher for the 20 and 21st century uh and a mindscape guest but also a personal friend so that hit very hard I 1:09 was sitting at a table with Dan and a bunch of other philosophers just a few 1:15 weeks ago at Santa Fe

He particularly praised Dennett for giving philosophical defenses of Atheism and Darwinism, and saying the mind is just a machine, so consciousness and free will are just illusions. But he was very much against telling the hoi polloi that they have no free will, or they may decide that they have no moral responsibility for their actions.

In past generations, philosophers did not want to inform us that God is dead, or that we are descended from apes.

Next, Carroll praised counterfactual reasoning.

ml pickle says your recent guests have 21:43 pointed to counterfactual reasoning as a key element of human advancement either as mental time travel or considering the 21:49 consequences of different initial conditions or empathy for the plights of others Etc I've begun to notice how 21:55 often I do it and to suspect it's true that Ed ability for example and perhaps 22:00 our overall success as a species depend upon it however I can't tell if it is required or most efficient or if it just 22:07 happens to be what I personally do how important do you think counterfactual reasoning is to effective prediction as 22:13 individuals or to our past and future advancement as a species it's hard to answer I mean that 22:20 the answer is super important basically but when you ask you know how important is it I'm not quite sure what how to 22:26 quantify it right um but I do do think that this idea of counterfactual reasoning maybe the first time we talked 22:31 about it was with Malcolm mcgyver when he was talking about the the initial evolutionary development of the capacity 22:38 for counterfactual reasoning when fish climbed onto land and could suddenly see a lot further than they could before and 22:46 yeah you're right we've talked about um people who have been thinking more specifically about how humans use those 22:52 capacities um I you know it's hard to imagine something oh Carl friston we 22:58 actually also talked with about that issue cuz I was I remember joking with him that of my two cats Ariel and 23:04 calaban one seems to be capable of counterfactual reasoning and one does not calaban just seeks the local minimum 23:10 he just wants to be as happy as possible in the moment I don't think the idea of other moments ever occurs to him whereas 23:15 Ariel is the stereotypical cat who you know when you open a door that she demands to have open she's like I don't 23:21 know do I want to open that do I want to walk to that threshold I'm not quite sure she's always thinking about the 23:26 possible bad consequences Etc and our uh feral cat our outdoor cat Puck who has 23:32 uh hung around outside our yard for a while um he's super cautious right 23:38 because this is what is keeping him alive so he doesn't do anything until he like thinks about it 20 different ways 23:43 so somewhere that's that's close to when this capacity in some minor uh key was 23:49 first developed evolutionarily but anyway yeah absolutely possible AB absolutely crucial because I think that 23:57 I suspect and I'm just making stuff up I'm not an expert on this but I suspect that the parts of the brain that are 24:03 good at in general abstract symbolic reasoning are either the same as or 24:09 closely related to the parts of the brain that are that are good at counterfactual reasoning

I would agree with this, except that there is no way to reconcile this with his views on many-worlds theory. In many-worlds, all counterfactual scenarios happen, so there is no such thing as a counterfactual.

If he really believed in many-worlds, there would be no free will either. Every decision is just a splitting of the worlds, with both branches equally real.

He also expresses support for the anti-Israel protests currently going on at college campuses.

The podcast goes on for three more hours. Let me know if I missed anything good.

Unscientific American

James B. Meigs writes:

Science journalism surrenders to progressive ideology.

Michael Shermer got his first clue that things were changing at Scientific American in late 2018. The author had been writing his “Skeptic” column for the magazine since 2001. ...

Shermer dug his grave deeper by quoting Manhattan Institute fellow Heather Mac Donald and The Coddling of the American Mind authors Greg Lukianoff and Jonathan Haidt, who argue that the rise of identity-group politics undermines the goal of equal rights for all. Shermer wrote that intersectional theory, which lumps individuals into aggregate identity groups based on race, sex, and other immutable characteristics, “is a perverse inversion” of Martin Luther King’s dream of a color-blind society. For Shermer’s editors, apparently, this was the last straw. The column was killed and Shermer’s contract terminated. Apparently, SciAm no longer had the ideological bandwidth to publish such a heterodox thinker.

The article gives many examples.

I have criticized these SciAm trends for years.

Maybe the title should be Unscientific Unamerican, since the magazine is now owned by a British company.

Many-worlds does not Solve the Measurement Problem

Brian Greene's third interview is with Carlos Rovelli:

I'll now give you a brief 0:21 summary of where we have gotten so far all right in our first conversation with 0:26 philosopher Elise Crow we discussed the basics of quantum mechanics namely that 0:33 the theory has at its core the idea that the best you can ever do in our reality 0:39 is make probabilistic predictions ...

we also explored how through quantum 1:36 entanglement reality has what we call a nonlocal quality that is what you do 1:42 here can have an instantaneous Quantum impact on something way over there and 1:48 such non-locality we found can thread not just through space but also through time

all right in 1:56 our second conversation with physicist and author Sean Carol we explored a 2:01 number of proposed resolutions to the quantum measurement problem most notably 2:07 spontaneous collapse theories as well as the many worlds interpretation of 2:13 quantum mechanics in which every possible Quantum outcome actually 2:18 happens but each takes place in its own Quantum Universe

No. Nothing can have an instantaneous nonlocal impact, and many-worlds does not solve the measurement problem.

I am surprised Greene would say this, because the advocates of many-worlds theory do not even claim to solve the measurement problem.

They argue that there is a wave function of the universe, and that the function will explain everything we see. Any mystery might be answered by understanding this function better. But it does not tell us why we see one outcome.

Or so I thought. I asked ChatGPT:

The many-worlds interpretation (MWI) is a fascinating and controversial view in quantum mechanics. Let’s delve into it and explore how it relates to the quantum measurement problem.

The Quantum Measurement Problem

The measurement problem arises from the mysterious behavior of quantum systems during measurement or observation. Here’s a brief overview:

1. Wavefunction Collapse: Before a measurement, a quantum system exists in a superposition of all possible states described by its wave function. However, upon measurement, the wave function appears to “collapse” to a specific state, leading to the observed outcome. This collapse is puzzling because it seems to violate the unitary evolution of quantum mechanics.

2. Where Do Other Possibilities Go?: If all possible outcomes of a quantum measurement have real existence, why do we observe only one outcome? What happens to the other possibilities?

Many-Worlds Interpretation (MWI)

The MWI, proposed by physicist Hugh Everett, offers an intriguing solution to the measurement problem. Here are the key ideas:

1. Parallel Universes: According to the MWI, the universe doesn’t collapse into a single state during measurement. Instead, it branches into multiple parallel universes, each corresponding to a different measurement outcome. In other words, every possible outcome occurs in a separate universe.

2. Wave Function Never Collapses: In the MWI, there is no collapse of the wave function. Instead, the entire universe (including the observer) evolves as a superposition of all possible states. Each branch represents a different version of reality, with no need for collapse.

3. Replicas of You and Me: In these parallel universes, there exist replicas of you and me, leading other lives. Each replica experiences a different outcome of the measurement. These universes coexist but remain mutually isolated.

Controversy and Philosophical Implications

The MWI challenges our understanding of knowledge and reality:

Controversy: Debates about quantum interpretations can be passionate, and the MWI is no exception. Some physicists find it elegant, while others reject it due to its radical departure from classical intuition.

Epistemological Question: The MWI raises fundamental questions about what constitutes knowledge. It challenges us to consider what kind of theory we accept as a claim to understand the world.

In summary, the MWI provides an alternative perspective that avoids wavefunction collapse, but it remains a topic of ongoing debate. Whether it fully solves the measurement problem is still a matter of interpretation and personal preference12. Feel free to explore further or ask more questions! 😊

I cites this Quanta article:

Why the Many-Worlds Interpretation Has Many Problems ...

it seemed that the central problem for quantum mechanics was the mysterious rupture created by observation or measurement, which was packaged up into the rubric of “collapse of the wave function.” ...

But Bohr and colleagues didn’t bring wave function collapse into the picture just to make things difficult. They did it because that’s what seems to happen. When we make a measurement, we really do get just one result out of the many that quantum mechanics offers. Wave function collapse seemed to be demanded in order to connect quantum theory to reality.

So what Everett was saying was that it’s our concept of reality that’s at fault. We only think that there’s a single outcome of a measurement. But in fact all of them occur. We only see one of those realities, but the others have a separate physical existence too.

Okay, I guess the Everett do claim that they have solved somethiung here. As you can see, they have not.

New Greene Videos spread Quandum Misinformation

Physicist Brian Greene, known mainly for overhyping string theory, has new interviews of Elise Crull and Sean Carroll on quantum entanglement and related topics.

You should know to be suspicious when they say the Nobel Prize committee got something wrong. Carroll complains that they gave a prize for disproving hidden variables, even though Einstein, Bohm, and Bell believed in hidden variables.

Yes, the prize was for doing experiments to prove them wrong.

Greene lets Carroll plug his favorite, many-worlds theory. They claim it is somehow simpler to assume zillions of unobservale worlds.

They do put their finger on the heart of the problem -- the theory requires rejecting probabilities.

Usually, when a theory assigns a probability to an event, it is an estimate of the likelihood. of the event occurring versus not occurring. Carroll has to reject that whole way of thinking. He has to say all events occur, and deny that probabilities mean anything.

He admits that many-worlds does not match our real-world experience, but says we need more research on the foundations of Physics to figure it out.

He complains that universities do not want people like Bohm and Bell who are concerned with this stuff. Actually he admits that they did not want Bohm because he was a Commie, and got his degree under the Commie J. R. Oppenheimer.

They all give misleading descriptions of nonlocality. There is no quantum nonlocality in the sense that doing something in one place has an immediate effect on a distant place.

There has been no Nobel Prize for quantum nonlocality. They also complain that the textbooks do not explain quantum mechanics adequately. This should make you suspicious. How is it that these guys have some profound quantum insights that are not recognized by the Nobel committee or the textbooks?

I am afraid that people watch these videos and think that they are learning something. No, they are getting some fringe ideas that mainstream physicists say is wrong.

Update: Carroll says:

just say we have a wave function and not only the electron has a wave function but you and I are part of the wave 11:14 function of the universe and we just ask what would be predicted by the [Schroedinger] equation if if we went back to the has a wave function but you and I are part of the wave 11:21 classical Paradigm where we just have stuff and an equation yeah what would happen and the answer is that that part 11:28 of the wave function let's say that has the electrons spin up and spin down it doesn't disappear when you do a 11:34` measurement a measurement is clearly defined in this picture as a physical interaction between the Observer and the 11:40 system and the decoherence part is also important and what happens is you end up in a 11:46 superposition of the electron was spin up and I saw it spin up plus the 11:51 electron was spin down and I saw it spin down and ever's entire contribution was to say and that's okay and ... yeah it's the leanest and meanest version of quantum mechanics it's just there's a wave function and an equation everything else pops

This is a little hard to follow, but he says classical mechanics uses equations to make predictions, and many-worlds is just doing the same thing to use the Schroedinger equation to make predictions.

But the equations of classical mechanics can also be used to predict probabilities. When you do, and make an observation that rules out some possibilites, then the appropriate state functions are updated accordingly. No one says that the equations create parallel worlds. So classical and quantum mechanics are essentially the same in this respect.

Carroll would say that hte difference is that the probabilities are real and fundamental in quantum mechanics, but not classical mechanics. But that is just his personal philosophical opinion.