New Lecture on Many-Worlds

Physicist Sean M. Carroll has a new lecture on The Many Worlds of Quantum Mechanics. Here is a 2-year-old lecture on the same subject.

A question at 1:04:00 asks for observable evidence for many-worlds. For example, could you prepare a Schroedinger Cat, and somehow verify that it is alive in one world and dead in another?

The correct answer is that there is no such evidence, and the whole concept of many-worlds is unscientific and unverifiable.

He dodges the question, and says that there are experiments that could disprove quantum mechanics.

Yes, of course, but textbook (aka Copenhagen) QM does not say the two cats can be observed.

His lecture is a pretty clear explanation of QM and many-worlds.

He says, at 35:40 that many-worlds is a theory, not an interpretation. I agree with that. The interpretations of QM all have the same predictions and observations. The interpretation is just a philosophical explanation for what the variables mean, but no experiment can say that one interpretation is any better than any other.

The Copenhagen interpretation is what Bohr and Heisenberg said. And maybe Schroedinger and Dirac. The textbook interpretation is the version of it found in modern textbooks.

Many-worlds is, in essence, the theory of QM with the part about observations and predictions removed. So many-worlds cannot make predictions, and cannot be tested or verified.

Carroll is a big proponent of many-worlds, but only because he believes it gives a better explanation of what is going on. But it does not explain anything, and is an unscientific theory.

In the older lecture, he admits at 37:00 that many-worlds cannot be tested. He excuses this by saying that the assumptions that go into many-worlds can be tested. Those assumptions are the same as with quantum mechanics, so every test of QM is also a test of many-worlds.

This is just a dodge. There is no test that can show a preference to many-worlds over textbook QM.

He then goes on to say that many-worlds is an unfinished theory, maybe some day someone will figure how many-worlds could make testable predictions. With the current knowledge of the theory, it deterministically predicts that all things happen in branched universes, so all predictions come true in some universe. The theory cannot be tested.

Israeli physicist Lev Vaidman has a new paper on Why the Many-Worlds Interpretation?:

A brief (subjective) description of the state of the art of the many-worlds interpretation of quantum mechanics (MWI) is presented. It is argued that the MWI is the only interpretation which removes action at a distance and randomness from quantum theory. Limitations of the MWI regarding questions of probability which can be legitimately asked are specified.... Some speculations about misconceptions, which apparently prevent the MWI to be in the consensus, are mentioned.

I give you arguments for many-worlds, as otherwise you would not believe that the theory is as stupid as it is.

Note that he says that MWI removes randomness and fails to predict probability, as if that were an advantage.

The only part of our experience, which unitary evolution of the universal wave function does not explain, is the statistics of the results of quantum experiments we performed. ...

Thus, the MWI brings back determinism to scientific description [8]. (Before the quantum revolution, determinism was considered as a virtue of scientific explanation.) We, as agents capable of experiencing only a single world, have an illusion of randomness. This illusion is explained by a deterministic theory of the universe which includes all worlds together.

Got that? It it deterministic about things we never see and fails to predict the probabilistic events we do see.

The MWI provides simple answers to almost all quantum paradoxes. Schr ̈odinger’s Cat is absurd in one world, but unproblematic when it represents one world with a live cat and a multitude of worlds with the cat which died at different times of detection of the radioactive decay. ...

The paradoxical behaviour of Bell-type experiments disappears when quantum measure- ment does not have a single outcome [9]. ...

The reluctance of a human to accept the MWI is natural. We would like to think that we are the center of the Universe: that the Sun, together with other stars, moves around Earth, that our Galaxy is the center of the Universe, and we are unhappy to accept that there are many parallel copies of us which are apparently not less important.

There you go. Your rejection of the idea that you are constanting splitting into parallel universes is just a natural human conceit about your own self-importance. You are like those narrow-minded astronomers who put the Earth at the center of the universe.

This is crackpot stuff. It is anti-science. It is saying that you can get paradoxes out of a theory by removing all predictions.

Grad Schools to Stop Using Standardized Tests

From an AAAS Science magazine editorial:

Earlier this year, the University of Michigan became the first US university to remove the requirement that applicants to its nonprofessional doctoral programs take a standardized test—the Graduate Record Examination (GRE). This decision will not, on its own, address inequities in admissions practice, nor the broader education barriers that many applicants face. But it is a major step toward an admissions process that considers all dimensions of a candidate’s preparation and promise—a holistic view that should be adopted by all universities if equity in education and opportunities is to be achieved. ...

What are the costs for admissions committees that use the GRE in admissions decisions? In short, the loss of talented applicants at every stage of the process.

This is the dumbing down of science grad schools. The purpose is to admit incompetent women and BIPOCs. There is no example of a talented applicant being lost. The talented ones are able to score well on the tests.

Test scores are the main way that talented students get into good schools, when they have deficiencies in their records. Ignoring the scores serves no purpose, example to enable sex and race discrimination. It is amazing to see America's leading science journal going along with this nonsense.

Google Quantum Computers Failed to Prove Anything

AAAS Science magazine announces:

Ordinary computers can beat Google’s quantum computer after all
Superfast algorithm put crimp in 2019 claim that Google’s machine had achieved “quantum supremacy”

If the quantum computing era dawned 3 years ago, its rising sun may have ducked behind a cloud. In 2019, Google researchers claimed they had passed a milestone known as quantum supremacy when their quantum computer Sycamore performed in 200 seconds an abstruse calculation they said would tie up a supercomputer for 10,000 years. Now, scientists in China have done the computation in a few hours with ordinary processors. A supercomputer, they say, could beat Sycamore outright.

Such results were reported previous on this blog, and by Gil Kilai, who points out that Google was wrong by ten orders of magnitude.

“I think they’re right that if they had access to a big enough supercomputer, they could have simulated the … task in a matter of seconds,” says Scott Aaronson, a computer scientist at the University of Texas, Austin. The advance takes a bit of the shine off Google’s claim, says Greg Kuperberg, a mathematician at the University of California, Davis. “Getting to 300 feet from the summit is less exciting than getting to the summit.”

Still, the promise of quantum computing remains undimmed, Kuperberg and others say.

No, they are not 300 feet from the summit. They are still at sea level.

The whole point of quantum supremacy is to find a computation where quantum computers are demonstrably faster that classical (Turing) computers. That has been a failure. No advantage has been shown at all.

The advance underscores the pitfalls of racing a quantum computer against a conventional one, researchers say. “There’s an urgent need for better quantum supremacy experiments,” Aaronson says. Zhang suggests a more practical approach: “We should find some real-world applications to demonstrate the quantum advantage.”

They are acknowledging that no quantum computer has demonstrated any advantage.

I have said here that the whole research program is misguided and doomed. Quantum computing is probably impossible.

Even if you didn't know anything about this subject, you would have to think the program is fishy. The QC proponents are collecting billions of dollars in research funds, and making wildly exaggerated claims, only to be proved wrong later. Look at how they are in denial. The biggest result of the last ten years is proven wrong, and they still say, "the promise of quantum computing remains undimmed".

The Prize for the Electroweak Model

The biggest Nobel Prize for the Standard Model was probably the 1979 prize to Glashow, Weinberg, and Salam for electroweak theory.

Peter Woit posted some info about bickering behind the prize. Apparently Salam's work was unoriginal and undeserving. Salam thought that he deserved to share the 1957 prize for parity violation, and lobbied heavily to get it for something else.

Apparenly also Weinberg used to be close buddies with Glashow, but did not want to share the prize with him. So Weinberg was eager to credit Salam in order to cut Glashow out.

I am not even sure Weinberg was so deserving. His contribution was a short 1967 paper that was not hardly cited by anyone, Decades later prizes were given for the Higgs mechanism and 'tHooft renormalization, and they were arguably more critical.

A couple of comments mention that Salam was the first Moslem to win a science prize. I do not know if that worked in his favor, or against him.

Next Quantum Computing Milestone will be in 2050

A new paper sketches the history of quantum computing:

We argue that quantum computing underwent an inflection point circa 2017. Long promised funding materialised which prompted public and private investments around the world. ...

We argue that the next inflection point would occur around when practical problems will be first solved by quantum computers. We anticipate that by 2050 this would have become commonplace, were the world would still be adjusting to the possibilities brought by quantum computers.

Note that the big advance of 2017 was in funding, not technological progress.

A turning point in the development of quantum computation appears around 2017. At this point, several long-promised large funding programs began such as the European Quantum Flagship and the American National Quantum Initiative Act (this happened around the world and was in the Billions of USD). Most national investments appear to keep a country compet- itive in technological development. There are many initiatives around the world adding up to more than 20 billion USD committed public funding. In addition, many private companies also invested dramatically around this time. Mean

We have to wait a long time for the next milestone.

When will we see another inflection point? It’s hard to tell. The saying goes that knowl- edge begets knowledge. And so development always seems to go increasingly faster. But the next jump might have to wait until practical problems of commercial value are regularly solved. This should take place perhaps even around 2050.

I reported here in 2019 that progress was doubly exponential. If that were true, we would already see commercial value. Instead we have to wait 28 more years.

I don't believe it. We will not see those commercial applications. I also don't believe that it will get billions in funding for three decades without commerical payoff.

My prediction is that in about ten years, everyone will be complaining that quantum computing failed because the funding dried up.

Capturing the Central New Lesson of the Quantum

Physicist John Wheeler once wrote:

What one word does most to capture the central new lesson of the quantum? ‘Uncertainty,’ so it seemed at one time; then ‘indeterminism’; then ‘complementarity’; but Bohr’s final word ‘phenomenon’ – or, more specifically, ‘elementary quantum phenomenon’ – comes still closer to hitting the point. [...] In today’s words, no elementary quantum phenomenon is a phenomenon until it is a registered (‘observed’ or ‘indelibly recorded’) phenomenon, ‘brought to a close’ by an ‘irreversible act of amplification’. (Miller and Wheeler, 1984)57

Brian Greene comments on the view that the essence of the quantum is entanglement. Maybe superposition is second. But he says that when he was in school, no one made a big deal out of entanglement.

I don't think any of these are so central to quantum mechanics. Yes, in a quantum mechanical system, particles are usually entrangled with others. But would you say that the essence of solar system gravity is that every planet exerts a force on every other? Maybe, but I doubt it.

Scott Aaronson has weighed in on the Bohr-Einstein debates. I added this comment:

If you believe in MWI, then both Bohr and Einstein completely missed what quantum mechanics is about. What makes QM unusual is not measurement, or entanglement, or superposition, or probability, or complementarity. It is the continuous splitting of the universe into parallel worlds, where essentially everything happens somewhere.

While Bohr and Einstein did not find Bell’s Theorem, they were probably aware of von Neumann’s 1932 textbook with a theorem that had similar conclusions. That is, under certain hypotheses, QM cannot be recast as a theory of classical variables.

Aaronson notes that von Neumann's assumptions have been criticized. Yes, that is true, but not the conclusion. Conventional wisdom has been since 1932 that a theory of classical variables will not work. So I do not think that Bell's theorem would have affected Bohr or Einstein at all.

The bigger issue is my first point. Aaronson and many others now say that they subscribe to many-worlds theory (MWI). If so, why is he even talking about these other issues? MWI is so bizarre and counter to science that it makes all the other issues trivial.

Only Greeks had the Pythorean Theorem

From the Wikipedia List of common misconceptions

The Greek philosopher Pythagoras was not the first to discover the equation expressed in the Pythagorean theorem, as it was known and used by the Babylonians and Indians centuries before him.[641][642][643][644] He may have been the first to introduce it to the Greeks;[645][643] the first record of it being mathematically proved as a theorem is in Euclid's elements which was published some 200 years after Pythagoras, so he could have been the first to prove the theorem.

I don't think that there is a misconception here.

The Pythagorean theorem is named after Pythagoras, but he was a Greek who lived 2500 years ago, and no one know what he exactly did.

Ancient Babylonians and Indians had examples of right triangles with a²+b²=c², but they did not have the theorem. As far as we know, only the Greeks invented mathematical proofs.

Babylon and India were doing arithmetic. Greece was doing real mathematics.

Speaking of math, Numberphile has a new video on 10^272,000 universes in string theory, more than previously announced. In the middle it casually mentions that they all have negative energy, and are therefore unphysical. Ultimately this is what string theory will be famous for.