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.