Carroll addresses Weaknesses of Many-worlds

I have criticized many-worlds theory as unscientific nonsense, as it requires rejecting probabilities, does not make predictions, and cannot reconcile theory with observations.

In case you doubt this, listen to Sean M. Carroll, a leading advocate of many-worlds. Here is his latest podcast:

19:02 Victor Tiffany says "After you answered my question about energy conservation in the many worlds interpretation of 19:08 quantum mechanics you added there are real worries that you can have about many worlds but energy conservation is 19:14 not a true scientific worry." So what are those real worries

i think I've said what the real worries are at different 19:20 times but you know not everyone listens to every word so I'll I'll it's worth mentioning again. It's been a while Um I 19:25 think there are two sets of worries that are that are valid um one is the 19:30 question of deriving the born rule the probabilities in many worlds and it's 19:36 not that I don't think we can I think we can I think I know how to do it but the 19:41 origin of probability in many worlds is very very different than what it would 19:46 be in a truly stochastic theory or in a truly stochastic theory. um single world 19:52 theory you can just say well there's something that we don't know and can never know about what will happen next 19:58 in quantum mechanics. And the best we can do is assign a probability to it And we can figure out what that probability is by looking at 20:05 the frequencies of previous events and we get that the born rule fits the data and it all sort of makes sense It's at 20:10 least it not only does it make sense but it's comfortable and familiar to us Okay

20:16 Whereas in many worlds as has been pointed out many many times uh every allowed outcome happens The word allowed 20:23 is super important there Some outcomes are not allowed all outcomes that are supported by the Schroinger equation and 20:30 the current state of the quantum state of the universe are allowed which is very very different than saying everything happens but anyway many 20:37 different uh outcomes actually do happen and with 100% probability they will 20:42 happen in one of the branches of the wave function. right if I have a spin that is a superposition of spin up and 20:48 spin down I measure its spin in one branch it's definitely going to be spin up in the other branch. it's definitely 20:53 going to be spin down nothing probabilistic about it So where do the probabilities come from and again.

I 20:59 think there's an answer to this question and it has to do with self-locating uncertainty and things like that But the 21:05 kind of answer it is is deeply different than the kind of answer it is in the case of a truly stochastic theory. And 21:11 therefore I think it is okay to worry that we are cheating Uh you know we know what the answer is that we want to get. 21:18 We want to get the borne rule We want to get that the probability is proportional to the wave function squared I think we do get that in a very natural way but a 21:25 very different way than what we're used to. So we should be thinking very very deeply about whether we're just cheating 21:31 ourselves.

The other thing to worry about in Everett is that it's a very austere 21:37 theory. So the origin of structure broadly construed in the quantum state 21:42 of the universe is a big question Why do we see a world with three-dimensional space and you know matter and energy 21:49 rather than just seeing a wave function. okay again I think it's perfectly possible to answer this question but I 21:56 think it is much less answered than the probability question because you know the answer that we want is a lot more 22:02 detailed and structured as it were than just the probability question.

So there's a lot of work to be done and this is one 22:09 of the biggest things that I'm working on myself right now um how do you take that abstract quantum wave function and 22:16 divide it up using words like emergence and coarse graining and and effective theories and things like that and say 22:22 that oh look there's a classical limit with matter and particles and things like that. The reason why this is a 22:29 uniquely Everettian problem is because Everett's theory is the simplest theory 22:34 of quantum mechanics. Um it is the one that doesn't have any extra stuff It just has the quantum state and the 22:41 Schrodinger equation.

Other approaches to quantum mechanics don't need to address 22:46 the structure problem because they just put the structure in as part of the 22:51 posits of the theory. You have particles moving in space if you're bohmian. You 22:56 have certain ways that the wave function collapses if you're an objective collapse person And all of these rely on 23:02 this extra structure. So they quote unquote answer the question by just in 23:08 you know making an assumption that it's there right and maybe it is there that's perfectly valid I think that it is 23:14 better if we can derive it from something more fundamental but that doesn't mean that it's not uh uh work to 23:21 actually do that derivation

If you listen carefully, he is acknowledging that these are problems with many-worlds. Probabilities do not make sense. Maybe it will all be explained by "self-locating uncertainty" or some other concept yet to be developed.

And it predicts wave functions as the "simplest theory", but no one has figured out how to relate the theory to what anyone observes.

The phrase "not even wrong" applies here. There is no theory that is scientific in any way. It is all a delusional fantasy. He complains that Pres. Trump is probably not going to renew his federal grant to philosophize about this stuff, but this is crazier than transgender mice. There is no possibility of any good coming out of many-worlds theory.

Any scientific theory has to face the fact that if you look at the range of possible events, some things happen and some do not. Many-worlds theory says you get a simpler theory by dropping that fact, and assuming that anything can happen. It refuses to even say that some outcomes are more likely than others. It assures us that future work will make it all make sense somehow.

Listen to Carroll if you think I am misrepresenting many-worlds.

Columbia and Harvard are Anti-American

Peter Woit continues to rant:

Obviously I’m not a lawyer, but it’s impossible for me to believe that under the US constitutional system the president can legally issue an order to remove funding from an institution either because he thinks (see point 67 in the complaint) “Wouldn’t that be cool?” or because he wishes to take control of an institution he doesn’t like and remake it to his liking. ...

Since the beginning of this I’ve been highly frustrated by the difficulty of getting people (from the Columbia trustees on down…) to focus on what seems to me the simple and obvious issue: it’s a complete collapse of the US constitutional system to allow the executive to just defund an institution that displeases him, with the excuse for this defunding not relevant. If you accept that this is OK, you are accepting that dictatorship is OK.

No, it is not a dictatorship. Pres. Trump was popularly elected, and he is doing what he promised the voters.

Columbia and Harvard are anti-American. They break laws against racial discrimination. They are controlled by extreme leftists. They deny free speech to conservatives, while they coddle Gaza advocates who celebrate killing Jews. They get billions in government contracts, and overcharge for administrative overhead.

The colleges have an obligation to obey the law with the federal tax money they get. Every previous President threatened to withhold money if colleges do not comply. The only thing different today is that the colleges are dominated by Trump-haters.

Columbia and Harvard do a lot of good research, but most of it has no public value. The government is running big deficits, and a lot of things need to be cut.

Physicists have talked for decades on the benefits of string theory, anti-deSitter space, black hole interiors, supersymmetry, multiverse, and many other ideas of no practical value. It is all dishonest.

Scott Aaronson posted similar rants, but now announces

It’s crucial for people to understand that, in its total war against universities, MAGA has now lost, not merely the anti-Israel leftists, but also most conservatives, classical liberals, Zionists, etc. with any intellectual scruples whatsoever.

No. Harvard is suing Trump, but will likely lose on the main issues. Harvard will surely compromise, make some changes, and continue to be left-wing propaganda.

From a comment on Aaronson's blog:

I think it would be very beneficial to analyze the demands that Harvard fights so fiercely; perhaps some of them actually make sense. Would you mind if we take a look?

1. A non-specific preamble about leadership.

2. Merit-based hiring; no more racist preferences; screen for plagiarism. What’s wrong with any of that? Do you want less qualified professors with the politically preferential background? Do you want plagiarism?

3. Merit-based admission. What’s wrong with that? Do you want legacy and politically motivated student accepted and the most qualified rejected?

4. Pretty much “don’t admit Hamas operatives who misinform and inflame students.” What’s wrong with that? Do you want the horrible antisemitism of Harvard, Yale, Columbia to persist?

5. Viewpoint diversity. Indeed, social sciences and humanities department turned into echo chambers where academic discourse is effectively suppress. Would it be wrong to stop screening against conservatives and to allow faculty and students express a variety of opinions?

6. Stop antisemitism; report incidents of antisemitism. What’s wrong with that? Do you want the hatred to continue?

7. Get rid of DEI. DEI is one of major reasons for much of the above trouble. DEI is openly racist and contrary to merit-based hiring and admissions.

8. Accountability for misdeeds. Is anybody offended by the proposition that Harvard “forbids the recognition and funding of, or provision of accommodations to, any student group or club that endorses or promotes criminal activity, illegal violence, or illegal harassment”?

9. Whistleblower protection.

10. Transparency.

What’s so awful in any of these demands that Harvard should “fight fiercely”?

A lot of this has to do with Jewish issues, but my guess is that most Americans do not care about those issues, one way or the other.

Jews are going nuts with Hitler comparisons. Others wonder: was Hitler really trying to do the above ten items?

Woit refuses to admit that the colleges have a problem. Aaronson admits that the colleges have a problem, and agrees with Trump telling them to improve, but does not agree with Trump threatening to cut off money:

To win scientists’ everlasting love and support, all a more conservative political movement would need to offer is:

(2) We’ll fund and appreciate you, minus that other stuff.

All Trump can do is to threaten to cut off money, if he wants them to change. Columbia and Harvard have still refused to obey Trump's interpretation of the law.

My Definition of Science

I posted:

Broadly speaking, science consists of making observations, formulating theories, making prediction probabilities, and then making measurements to reconcile theory with experiment.

All science obeys all four steps, as far as I know.

I criticized many-worlds theory as only obeying the first two. It uses observations and the Schroedinger equation, but does not make predictions or reconcile experiments.

People find that surprising, but it is true. Making a prediction inherently implies that other things do not happen. But many-worlds theory says that all the other possibilities also happen. Probabilities are meaningless in the theory.

Astrology is better at being a science. It uses astronomy observations, has a theory, and makes predictions. It just doesn't reconcile experiments.

Ancient astronomy easily qualifies as science, even though they had flawed ideas about the underlying motions and causes.

Superdeterminism fails all four steps. It does none of them. It is not based on any theory or observations. Its advocates argue that our observations do not even reflect the natural laws, because unseen forces prevent us from testing those laws. If a drug seems to do better than a placebo in a controlled strudy, then it was only because the sicker patients were accidentally put into the placebo group.

String theory does not make predictions or reconcile experiments. Whether it does the first two steps is debatable.

A lot of theoretical physics today has no connection to experiment. An example is theorizing about the interior of a black hole. Or inflation-created universes beyond our horizon.

Watch Google Dodge Quantum Questions

This CNBC interiew is filled with quantum computer hype, and includes a Google quantum AI spokesman answering questions.

Not really. He dodges all the questions, and just babbles with things like "there's a lot of nuance in quantum computing".

Google Lost The AI Lead. Can Quantum Put It Back on Top?

I do not agree that Google lost the AI lead, or that quantum will help it in the AI race. Google has been a leader in AI for about 15 years. It is still at or near the top with protein folding, chess and go, and Gemini 2.5. And of course its big money-maker, which is using AI to target ads for everyone.

The supposed Google AI lead is based on a popular 2017 paper, but a new Nature journal survey rates a Microsoft AI paper as the most cited in the 21st century.

Scott Aaronson makes an appearance expressing skepticism about Microsoft's quantum computer.

In another video, physicist Angela Collier celebrates Bezos Blue Origin sending six women into space. Just kidding. She does a 40-minute rant against it.

And Peter Woit and Scott Aaronson are still arguing over the proper response to Trump being Hitler reincarnated. The basic facts are that Columbia and Harvard are extremely rich, they are not complying with federal law, they are receiving billions of dollars contingent on obeying federal law, they are refusing to comply, and they are squealing about Trump threatening to withhold those funds. Their faculties are dominated by leftist Trump-haters who do not want to compromise.

Woit and Aaronson think this could have been settled in quiet negotiations. Or maybe they think colleges should not have to obey the law, I am not sure. But it is extremely clear that Columbia and Harvard will not comply unless funds are withheld. Harvard already lost a racial discrimination case in the US Supreme Court, and it continues to discriminate as before.

The arrogance of these colleges was on full display when their presidents testified before Congress in Dec. 2023. The public backlash was so fierce that those presidents ended up resigning. You would think that these colleges would be eager to obey the law, but they stubbornly refuse.

Woit and Aaronson pointedly disagree on some Jewish issues, but that seems minor compared to their hysterical Trump hatred, and their overdramatizing of these colleges being held accountable. I doubt that they realize how much they seem like spoiled children.

Can Gravity be Renormalized?

A big achievement of XX century Physics was renormalizing quantum electrodynamics (QED), by Feynman and others. That showed how infinities could be canceled out, so the theory can make predictions in all energy ranges.

QED is a gauge theory on the circle group. Then 'tHooft showed renormalization applied to gauge theories over other groups. Since the known particles were classified by group representations of other groups, that opened the way to the Standard Model. They just had to use the groups already linked to the the particles, and apply gauge theory renormalization.

Gauge theory was the only known renormalizable theory, so there was no choice.

Not everyone agrees that renormalizability is so important. The later invention of effective field theory seemed to bypass renormalization. String theory also provides another approach.

Attempts to quantize gravity have failed because general relativity is not renormalizable. This led people to say string theory is the only game in town, except for maybe loop quantum gravity. Neither approach has produced a quantum gravity theory.

I did not know that general relativity could be easily modified to a theory that is renormalizable.

Luca Buoninfante posts a new paper:

An important theoretical achievement of the last century was the realization that strict renormalizability can be a powerful criterion to select Lagrangians in the framework of perturbative quantum field theory. The Standard Model Lagrangian (without gravity) is strictly renormalizable from a perturbative point of view. On the other hand, the inclusion of gravity seems not to respect this criterion, since general relativity is perturbatively non-renormalizable. The aim of this work is to provide concrete evidence that strict renormalizability is still a valid criterion even when applied to gravity. First, we show that adding quadratic curvature terms to the Einstein-Hilbert action gives rise to a strictly renormalizable theory known as quadratic gravity. Second, we argue that this unique theory represents the most conservative approach to quantum gravity and, at the same time, is highly predictive, as it can explain new physics beyond general relativity already in the sub-Planckian regime.

The simplest way to define a physics theory is to specify the Lagrangian. If you do that for the Standard Model, you can fit it on a t-shirt.

General relativity is the theory derived from the scalar curvature R being the Lagrangian. Or subtract a constant, for general relativity with a cosmological constant. This paper says that you just have to add a quadratic term in the curvature, such as R² or other contractions of the squared Riemann tensor, and you get a renormalizable theory. News to me. This model is sometimes called Starobinsky inflation, and used to explain the early universe.

We do not have any way to test quantum gravity, so the best argument for this approach is that renormalizability has been such a crucially important criterion in the past. It is how we got the Standard Model.

Adding a quadratic term is a bit like Einstein adding the cosmological constant to general relativity. It could not be measured at the time, and was intended to improve the global properties of the theory. It was only measured 80 years later.

Maybe someday this quadratic gravity will be seen as the natural way to modify general relativity to handle extreme conditions.

Everybody always says that quantum mechanics and gravity are incompatible. There is no experiment that shows a problem, so there is only a theoretical incompatibility that might only apply at the center of a black hole or in the first nanosecond of the big bang.

Now I question this. As this paper explains, just add a couple of quadratic terms to the gravity Lagrangian, and there is no problem renormalizing quantum field theory predictions. The only problem is that we do not have experimental data to determine the coefficients of those extra terms. Presumably they are small enough not to affect the known celestial mechanics and cosmology.

So we have a perfectly good quantum gravity theory, with a couple of undetermined coefficients. Those coefficients are too small to affect any of our observations. Viewed that way, it is incorrect to say that there is any incompatibility between gravity and quantum theories.

A few years ago, you could have said that general relativity was incompatible with the concept of a quantum zero point energy. Now the cosmological constant is accepted, and that is believed to be the energy. Maybe we just need to add one or two more cosmological constants, and quantum gravity will cease to be a theoretical issue.

About World Quantum Day

Monday was World Quantum Day:

This Doodle celebrates World Quantum Day, an annual celebration that improves understanding of quantum physics and technology. The date, April 14th, represents the first three digits of Planck’s constant, which describes the relationship between the energy and frequency of a quantum of energy (such as a photon): 4.14×10−15 eV·s

Brian Cox Explains Quantum Physics

New video: Physicist Brian Cox explains quantum physics in 22 minutes:

"Quantum mechanics and quantum entanglement are becoming very real. We're beginning to be able to access this tremendously complicated configuration space to do useful things."

In just 22 minutes, physicist and professor Brian Cox unpacks the subatomic world, beginning with the theories as we understand them today.

I do not think these explanations are helpful. He says the theory was not practical until recently, when quantum computers started being built.

15:13 Now you go back a few decades 15:16 then I think you could say that the interpretations 15:21 of quantum mechanics 15:23 are very interesting and very important, 15:28 because we're talking about the nature of reality. 15:30 But you might say, well, it doesn't really matter 15:33 so much practically, right? 15:35 If that now, I have a lot of colleagues in physics 15:38 who would, I think rightly hate that description 15:41 because what we're trying to do 15:42 is understand reality, what physics is. 15:45 But now particularly, I think, with the possibility 15:50 of building quantum computers, 15:52 this attempt to understand how large systems 15:55 of quantum mechanical objects behave 15:57 is becoming extremely important, 15:59 because a quantum computer 16:02 is a device which is built out of qubits.

No, the annual world economy has about a trillion dollars based on quantum mechanics. The theory is essential for transistors, silicon chips, lasers, led lights, solar panels, cameras, digital displays, and many other technologies. So the theory has been very practical for 70 years. On the other hand, no one has demonstrated any utility for quantum computers.

He spends time explaining that quantum physics involves probabilities, wave effects, and predictions from conservation laws. But none of these are unique to quantum mechanics. I do not think he explained the subject at all.

The most important new ideas in quantum mechanics are that (1) observables are non-commuting operators; and (2) electrons, and everything else, have wave properties but are observed as eigenvalues. Those are the quantum mysteries.

All the other stuff, the probabilities, the Schroedinger cats, the supposed nonlocality, the entanglement, the superpositions, etc., just are not that mysterious. Cox is a leading Physics expositor, and he can do better.

Physicist G. tHooft got a Breakthrough Prize and he was interviewed about his strange quantum ideas.

Quantum mechanics is the possibility that you can consider superpositions of states. That’s really all there is to it. And I’d argue that superpositions of states are not real. If you look very carefully, things never superimpose. [Erwin] Schrödinger asked the right questions here: You know, take my cat, it can be dead; it can be alive. Can it be in a superposition? That’s nonsense!

And he was quite right. People shouldn’t continue to insist that a dead cat and a live cat superimpose. That’s complete nonsense ...

What I’m saying is: we must unwind quantum mechanics, so to speak, as to see what happens underneath. And until the quantum technologists start doing that, I believe they won’t make really big progress.

He believes in superdeterminism as a way to save locality. He complains that no one takes him seriously.

His ideas are too silly to take seriously. He says QM is just being able to consider more than possibility. What is quantum about that? Classical mechanics allows considering multiple possibilities. And superdeterminism is really kooky.

Physicist Ethan Siegel is usually pretty good, but he rambles about the multiverse in his latest video.

At 1:18:50, he says particle spin has just a discrete degree of freedom, because it is just up or down, in each of the three dimensions. But decay into fixed-energy photon has a continuous degree of freedom, because photons can go in any direction. I did not follow that. Spin can also be in any direction. Spin is different from momentum in that different directions do not commute, and spin magnitude can only have discrete values. But in his example, both the momentum and spin have a known magnitude. So I think he is making a mistake here, but I could be wrong.

My real objection is to all the multiverse junk.

54-year-old Paper wins Breakthrough Prize

A $3 million prize was just announced:

Special Breakthrough Prize in Fundamental Physics

Gerard 't Hooft, winner of the Special Breakthrough Prize in Fundamental Physics, is one of the world’s most pre-eminent theoretical physicists. In the early 1970s he made crucial contributions to the foundations of what would later become known as the Standard Model of the subatomic particles. He proved that Yang-Mills theories (the mathematical framework underlying theories of both the weak and strong nuclear forces) make sense when treated quantum mechanically – that they can give finite, calculable results rather than meaningless infinities – thus validating theories which became central to the Standard Model. He made several crucial contributions to understanding the theory of the strong force, including resolving a major problem involving the masses of particles through special field configurations called instantons; he developed new mathematical tools for studying strongly interacting quarks; and he introduced the fruitful approach of studying the strong force by imagining it is mediated by many more varieties of quarks and gluons than it actually is. These and other contributions helped establish the Standard Model as a workable theory and provided powerful tools for calculating its predictions. 't Hooft has studied the quantum effects that can explain how information is processed in black holes, which led to the development of the holographic principle in cosmology, and possibly to new alternative ways to interpret quantum mechanics.

His 1971 paper on how to renormalized gauge fields was indeed a breakthrough, and probably did more to create the Standard Model than anything else. But it is now 54 years later.

I do not think that very many people realize what a failure theoretical physics has been for the last 50 years. It is hard to find anthing that can be called a breakthrough. The Golden Age of Physics is long gone.

Consciousness and Physics

Sam Harris has a big following, mainly promoting Atheism, Eastern religious meditation, Trump-hating politics, and lack of free will. It turns out that his wife is more preoccupied with consciousness than he is, and announced an audio documentary on it. You can hear free interviews on it here and here.

Her main point is that if consciousness is fundamental, then that would be a paradigm shift.

She expects physicists to be experts on what is fundamental, so she interviews a bunch of them for the documentary, including Brian Greene and Sean M. Carroll.

These guys are odd choices, because they do not believe in free will, and one cannot have very much consciousness without free will. To me, the ability to make decisions is at the core of my consciousness.

Here is Greene's view:

Brian Greene, a prominent theoretical physicist known for his work on string theory, does not believe in free will in the traditional sense. He argues that the universe operates under deterministic physical laws, leaving no room for human agency to override them. In his book Until the End of Time (2020), Greene asserts that everything—thoughts, actions, choices—is the result of particles and fields obeying quantum-mechanical and classical rules. During a 2020 Harvard Science Center lecture, he said, “We are made of these exquisitely ordered, wonderfully choreographed particles of nature governed fully by the physical laws, no free will whatsoever.” He sees free will as an illusion, a sensation we experience, but not a reality grounded in physics. In a 2014 blog post (Atheism and the City), he’s quoted saying, “The sensation [of free will] is real, but the choice seems illusory. Laws of physics determine the future.” For Greene, our decisions are just outcomes of particle interactions, not independent acts of will.

Carroll is even more extreme in that he fully accepts many-worlds theory, so no decisions are made. Just world-splittings.

Sam Harris is more extreme than that. While Greene and Carroll accept an illusion of free will, Sam Harris denies that, and claims that he has no feeling of free will.

Do not take the Harris's too seriously. While they claim to rely on Physics, nothing they say depends on any physics. Instead it is largely based on their experiences taking psychodelic drugs.

A new paper carefully explains the error in thinking that modern science requires denying free will:

Reframing the Free Will Debate: The Universe is Not Deterministic
Henry D. Potter, George F.R. Ellis, Kevin J. Mitchell

Free will discourse is primarily centred around the thesis of determinism. Much of the literature takes determinism as its starting premise, assuming it true for the sake of discussion, and then proceeds to present arguments for why, if determinism is true, free will would be either possible or impossible. This is reflected in the theoretical terrain of the debate, with the primary distinction currently being between compatibilists and incompatibilists and not, as one might expect, between free will realists and skeptics. The aim of this paper is twofold. First, we argue that there is no reason to accept such a framing. We show that, on the basis of modern physics, there is no good evidence that physical determinism of any variety provides an accurate description of our universe and lots of evidence against such a view.

They are correct. If you think modern science requires determinism, then you are a couple of centuries out of date.

Of course the determinists, from Einstein to Greene, know all about quantum mechanics and its indeterminacy. But they act as if QM is just classical mechanics with some randomness added in, and say that no one could have agency over randomness, by definition. This misunderstands QM. The above paper addresses this argument, although they refer to forthcoming papers for details. It also address arguments from unitarity, time-reversal, block universe, and causal determinism.

Colleges have Big Jewish Fights

Columbia Mathematical physicist Peter Woit is ranting about campus politics:

I can’t stop myself from thinking about what happened in 1933 in Germany. If you don’t know this history, you really should read about it. The analogies with what’s going on now are remarkable.

He is not referring to the Columbia radicals who want to kill Jews, but the Trump administrations efforts to stop anti-semitism.

Scott Aaronson says:

Peter, your university’s antisemitism task force — formed with no Trump involvement — produced a harrowing report last year filled with specific incidents that added up to a pretty compelling case for Jewish and Israeli students (unless anti-Zionist) to want to steer clear of Columbia. If your position requires condemning all of your colleagues on that task force as liars, fanatics, and snitches, then that seems to me like an excellent way to lose this battle and alienate most of those who would otherwise be your allies. ...

If I’m unhinged and in need of psychiatric help, then so is the entire membership of Columbia’s antisemitism task force, as I’ve done nothing more extreme than try to balance my fear of Trump with my fear of what the task force concluded in its 120-page report.

Woit replies

The university has to somehow manage this, it’s a difficult problem. It’s being made a hundred times more difficult by people like Scott Aaronson who have no idea what’s going on here, but are so intent on joining the fight to destroy the other side that they will enthusiastically collaborate with the Fascists we’re trying to resist.

So Woit and Aaronson question the sanity of each other. Aaronson is a Jew married to an Israeli, and Woit is a gentile from Eastern Europe.

The core of the problem is that Columbia and Harvard have become havens for left-wing crazies:

Last year, Harvard earned the worst score ever recorded in FIRE’s College Free Speech Rankings: Zero. This year, the elite Ivy makes a repeat poor performance — and finds fresh company at the bottom, with NYU and Columbia joining the unenviable list of “abysmal” schools for free speech.

With scores ranging from zero to 100, NYU plummeted nearly 30 points this year, and Columbia fared even worse, becoming the second school after Harvard to ever receive a zero. And Columbia, like Harvard, actually received a negative score that we rounded up to zero. The only reason Columbia was spared from receiving the title of this year’s Worst College for Free Speech is that Harvard’s actual score was even worse, a full 21 points lower.

So Columbia and Harvard do not allow free speech for right-wingers, but they do allow faculty and students to side with the Oct. 7 Gaza/Hamas attack on Israel and with generally attacking Jews.

Another part of the problem is that federal spending is out of control, and Trump administration efforts to hold grant recipients accountable has brought howls of protest from universities.

Update: Dr. Bee comments on Woit, Aaronson, and others. She notes that many support what Trump is doing.

Facing Reality is an Ugly Scar

To see how foolish the many-worlds theory (MWI) is, just read what the advocates say.

Lev Vaidman just posted The many-worlds view of quantum mechanics:

My explanation has two very different parts.

i) The ontology, stuff that exists, including laws constraining possible states of stuff and dynamical laws of time evolution of stuff.

ii) The prescription of correspondence of the state of stuff with our experiences which we inquire through our sensory organs, sometimes equipped with instruments like telescopes, microscopes, sonars, etc.

The ontology is all the parallel universes. But relating the theory to our experiences in part (ii) is impossible without probability, and that is rejected, so he settles for a theory that does not relate to our experiences.

In conclusion, physics explains all phenomena we observe on Earth extremely well. Collapse of a quantum state at measurement is an ugly scar on a beautiful quantum mechanics. The only role of the collapse is to avoid parallel worlds which anyway are not supposed to be seen according to the theory. Without collapse we have to accept MWI. Apart from the disappointment in understanding that I am not a unique Lev Vaidman, and that there are multiple copies of me in other worlds, MWI allows me to believe that by and large I understand how the universe works. For me, parallel worlds are not a too high price to pay for understanding Nature.

So he says the collapse is just a way of avoiding the parallel worlds that we never see anyway. I call that facing reality, but he says it is an ugly scar.

He acts as if the collapse is peculiar to quantum mechanics, but it is not. All scientific theories do something similar when a prediction is compared to a measurement. The Bayesians call it adjusting their priors.

So what does he get from having of other worlds that cannot be seen? It allows him to believe that he understands Nature!

The many-worlders complain bitterly about the collapse being part of quantum theory, but it is very much part of many-worlds theory also. Instead of calling it collapse, they call it world-splitting. Instead of collapsing the wavefunction so that it better describes our universe, they say that the wavefunction decomposes into pieces where one piece describes our universe, and other pieces describe unobservable parallel universes.

The MWI does not solve the measurement problem, or explain the collapse/splitting, or do anything useful.

This is not Physics, and not science. It is too stupid for a rebuttal. There is not any substance to the theory. I would not even bother commenting on this nonsense, except that a great many of our leading physicists and physics expositors buy into it.

Broadly speaking, science consists of making observations, formulating theories, making prediction probabilities, and then making measurements to reconcile theory with experiment.

Many-worlds theory says to skip the last two steps. It denies that prediction probabilities make any sense, and it says that reconciling with experiment is an ugly scar that just rules out invisible parallel worlds. It is impossible to believe in many-worlds and have a scientific world view. For this reason, I doubt anything from Sean M. Carroll, Max Tegmark, and Leonard Susskind, even though they are all brilliant and explain some things very well.

Update: According to Tegmark, the term "ugly scar" is from Gottfried in 1989.

Using a Quantum Computer for Random Numbers

Prof. Scott Aaronson brags:

today JP Morgan Chase announced that, together with Quantinuum and DoE labs, they’ve experimentally demonstrated the protocol I proposed in 2018, and further developed in a STOC’2023 paper with Shih-Han Hung, for using current quantum supremacy experiments to generate certifiable random bits for use in cryptographic applications. See here for our paper in Nature—the JPMC team was gracious enough to include me and Shih-Han as coauthors.

Bloomberg reports:

JPMorgan Chase & Co. has generated and certified so-called truly random numbers using a quantum computer, in a world-first that the bank hopes will have applications for security and trading.

Researchers created the sequence using a quantum computer built by Honeywell’s Quantinuum, according to a paper published in the scientific journal Nature on Wednesday. JPMorgan researchers, alongside Argonne and Oak Ridge national laboratories and the University of Texas at Austin, then became the first to prove mathematically that they had produced “genuine randomness.”

Most so-called random number generators, which are important for encrypting sensitive data, aren’t actually random. They’re pre-determined sequences. Computers run on a set of programmed mathematical operations that will always return the same answer, raising the risk that hackers with access to increasingly sophisticated computing power could crack encryption codes.

Computers are not really deterministic. They have a CPU with a built-in hardware random number generator. Those numbers are as genuinely random as anything else. The advantage of Aaronson's method is that the numbers are certifiably random.

Aaronson admits that the method is not really practical, and it is hard to imagine a use for it. If you want to generate a private cryptographic key, there are much easier ways. Eg, you could record a video of yourself and hash it. You could use the CPU generator. You could use the generator that comes with password and bitcoin apps.

There are also public random number generators, such as here and here. It is a little tricky for multiple parties to agree on a fair lottery, but there are many ways that are a whole lot easier than using a quantum computer.

One way is to agree on a lottery for a particular day is to agree to has (with sha256, say) of the NY Times front page that day, or the stock market trades, or the baseball scores. A drawback is that if a lot of money were at stake, maybe someone would bribe a NY Times editor to drop a story or a baseball player to throw a game in order to influence the hash. Such attacks would be extremely improbable.

The Rise of Stochasticity in Physics

New paper:

The rise of stochasticity in physics
Hans A. Weidenmüller

In the last 175 years, the physical understanding of nature has seen a revolutionary change. Until about 1850, Newton's theory and the mechanical world view derived from it provided the dominant view of the physical world, later supplemented by Maxwell's theory of the electromagnetic field. That approach was entirely deterministic and free of probabilistic concepts. In contrast to that conceptual edifice, today many fields of physics are governed by probabilistic concepts. ...

The success of the theory led physicists to adopt what became known as the mechanical world view. According to that view, all physical processes can be understood on the basis of Newton’s equations. The theory is completely deterministic. There is no room whatsoever for probabilistic concepts which play a role only in the analysis of statistical and systematic errors. Such errors were considered epistemic and, therefore, did not challenge the validity of the mechanical world view. (A notable exception is the discovery of the dwarf planet Ceres in 1801. After its discovery, the planet was lost and could be retraced only with the help of Gauss’ statistical least-squares method).

That is a pretty big exception. The Newtonian mechanics seems deterministic, but in practice it is not. Like Gauss, you have to make imperfect observations, do some statistical estimations, and make a probabilistic prediction.

The whole field of AI used to be mostly deterministic, but now they follow the same stochastic pattern. They run on deterministic computers, and use lots of deterministic formulas, but the big AI models make very heave use of statistical estimates and probabilistic predictions.

I no longer agree with saying that classical mechanics is deterministic. All of science is inherently stochastic.

Historically, probability was developed after calculus. I thought that calculus would have been the conceptually more difficult subject.

Advocates of many-worlds theory reject probability. The theory does not make some worlds more likely than others, as some assume. I think that the followers must have some fundamental misunderstanding of what probability in math and science is all about.

Today, use of probability and statistics is pervasive in all of science. Every prediction is made with some probability, and every test is analyzed with statistics. So I do not think that there is any such thing as deterministic science. Classical physics is not, and neither is biology, chemistry, medicine, or anything else.

In summary, in the last 175 years physicists have been led or been forced to ascribe an ever increasing role to probability in the description of nature. I have listed four causes for that development: Loschmidt’s number supporting Maxwell’s theory, irreversibility leading to Boltzmann’s approach, Bequerel’s discovery, spectral lines and black-body radiation leading to quantum theory, and Poincare’s discovery of classical chaos. Random-matrix theory is different. It was not imposed on physicists by an experimental or theoretical discovery but was introduced to compensate for the incomplete knowledge of the Hamiltonian.

He is right about those trends, but probability would have become essential in all of science even without those four trends.

Investing in 150 Proof-of-concept Projects

More quantum computer hype in the business news:

A Practical Quantum Computer Is Coming! But When?

CNBC 3.85M subscribers

Google, IBM, Amazon, Microsoft and Intel are all working on quantum technology, as are numerous startups. At its annual GTC developer conference this week Nvidia CEO, Jensen Huang, announced the company was opening a quantum research lab in Boston. Governments around the world have also pledged over $50 billion to develop the technology. Quantum computers hold huge potential, with experts saying that they could transform entire sectors including material science, pharmaceutical research and financial services. But despite massive advancements in the field in recent years, right now, these quantum computers aren’t able to solve big real-world problems. CNBC's Kate Rooney visits California-based startup, PsiQuantum and spoke to experts about the major challenges this tech still faces as engineers work to transition quantum computers from lab experimentation to commercial viability.

As the video explains, many billions are being invested, in a huge fear of getting left behind. Much of it is going into "proof of concept" projects.

15:54 Public interest in quantum technology is growing. 15:57 The number of quantum computing proof of concept 16:00 enterprise projects surged by 50% between 2022 and 16:04 2024, to over 150 active projects. 16:08 Consulting firm Booz Allen, Airbus Ventures and Bosch 16:12 Ventures have all invested in quantum computers. 16:14 Meanwhile, Shadbolt says Illinois is investing $500 16:17 million to construct a quantum computing campus in 16:21 Chicago, of which Psi quantum will be the anchor 16:24 tenant. Psi quantum has also received $620 million from 16:29 the Australian and Queensland governments to 16:31 build a utility -scale quantum computer in 16:34 Brisbane, which the company says will be operational by 16:37 the end of 2027. 16:39 Experts say, investing now is a smart move. 16:43 When quantum computers reach quantum advantage, 16:46 which is effectively the period in which quantum 16:48 computers outperform classical computers at 16:52 important real world problems, 16:54 it will be much, much harder to get your 16:56 hands on a quantum computer unless you're developing 16:59 partnerships with the major providers right now.

Some people are going to see this, and think that quantum computing must really be a hot technology, to have so much investment, and even a panic to invest more.

I think the opposite. With generous funding to a lot of super-smart physicists of 150 proof-of-concept projects, and none proving that the concept is viable, I think that it is probably impossible.

The Nvidia CEO got some heat for saying quantum computing is many years away:

He also expressed surprise that his comments were able to move markets, and joked he didn’t know that certain quantum computing companies were publicly traded.

“How could a quantum computer company be public?” Huang said.

Forty years ago, a company had to be profitable to go public. Later, companies could go public with a large market share and user base, and no profits. Now a company can go public with no product, no customers, and not even a proof of concept.

Meanwhile, the England crypto spooks have published a roadmap for protecting communications from quantum computers:

In our 2023 white paper, the NCSC outlined the need to prepare for migration to post-quantum cryptography (PQC) due to the threat to cryptography posed by future developments in quantum computing.

The guidance defines three phases for migration.

The first of those involves carrying out a full discovery exercise to understand your estate, and identify services that are dependent on cryptography that will need to be upgraded to PQC. This then enables you to build an initial migration plan, identifying priority services for migration. 2028 is the target date for completing all of this.

The second phase is carrying out the highest priority migration activities that you have identified, and refining your plan as the PQC ecosystem develops so that you have a thorough roadmap for completing migration. You should aim to complete this phase in 2031.

The third phase is to complete migration to PQC of all your systems, services and products, with 2035 as your target.

That does not mean that they think SSL/TLS encryption will be broken in 2035. They like to preserve secrets for 50 years, so maybe they are worried about attacks in 2085.

Quanta magazine reports that quantum algorithms have been disappointing:

This contest almost always ends as a virtual tie: When researchers think they’ve devised a quantum algorithm that works faster or better than anything else, classical researchers usually come up with one that equals it. Just last week, a purported quantum speedup, published in the journal Science (opens a new tab), was met with immediate skepticism from two separate groups who showed how to perform similar calculations on classical machines.

Military intelligence will switch to PQC, but I would not be surprised if the private sector never switches.

D-Wave Claims Quantum Supremacy

Quantum computing stock market values are up again, as D-Wave got a paper published in AAAS Science, the top American science journal, claiming quantum supremacy. But SciAm reports:

Loud declarations of various types of quantum advantage aren’t new: Google notably made the first such claim in 2019, and IBM made another in 2023, for example. But these announcements and others were ultimately refuted by outside researchers who used clever classical computing techniques to achieve similar performance. In D-Wave’s case, some of the refutations came even before the Science paper’s publication, as other teams responded to a preliminary report of the work that appeared on the preprint server arXiv.org in March 2024. One preprint study, submitted to arXiv.org on March 7, demonstrated similar calculations using just two hours of processing time on an ordinary laptop. A second preprint study from a different team, submitted on March 11, showed how a calculation that D-Wave’s paper purported would require centuries of supercomputing time could be accomplished in just a few days with far less computational resources.

There is also a lot of skepticism about Microsoft's claim of a topological qubit.

Gil Kalai has not conceded, and has doubled down with his Quantum Computing Skepticism.

Let's review the arguments in favor of quantum supremacy. The most common one is that qubits can be 0 and 1 at the same time, just as Schrodinger's Cat can be alive and dead simultaneously. Operations on qubit are thus able to examine an exponential number of possibilities at the same time, leading to an exponential speedup in computation.

Scott Aaronson says that this is wrong, because it misleadingly predicts an exponential speedup where none is possible. Instead he says the speedup comes from negative probabilities.

The QM probabilities are never negative. That is just his way of making destructive wave interference sound mysterious. When you say a computational speedup comes from wave interference, it is harder to understand.

Aaronson falls back on the argument that it is up to the skeptic to prove that quantum computers are impossible, and that would be very interesting, but no one has done that.

The many-worlds folks say that the speedup comes from computation being done in parallel universes. Most people say that there is no way to observe those parallel universes, but we are supposed to believe that they speed up computations somehow.

Feynman's original argumen was that simulating QM can be exponentially slow, so it can be faster by running a quantum experiment. You can do a chemical reaction faster than you can simulate it from first QM principles. Okay, that is true, but it is a big leap to using QM to factor large integers.

Finally, there is the argument that quantum researchers have made so much progress already. Yes, but maybe it is like slimbing trees to make progress towards going to the Moon. There is progress, but the goals seem as far away as ever. Nobody has a convincing experiment showing that quantum computing is possible.