Foundations of General Relativity

The foundational principles of general relativity are said to be the equivalence principle, and general covariance. This new video disagrees.

Here is how I see it. The equivalence principle could also said to be foundational to Newtonian classical gravity, and it is only associated with general relativity for historical reasons.

General covariance is a mathematical principle, and it is not clear that any mathematical principle, by itself, has any physical consequences. As Einstein is quoted:

As far as the laws of mathematics refer to reality, they are not certain; and as far as they are certain, they do not refer to reality.

The laws of math do have consequences, but they require interpretation.

We normally say that Euclidean geometry has physical consequences, but that is only because of some assumptions about how idealized points, lines, planes, etc. correspond to physical entities.

Historically, covariance under Lorentz transformation was crucial to the presentations of relativity given by Poincare in 1905 and Minkowski in 1907. Einstein had a weaker version that was more similar to what Lorentz published in 1895.

Einstein was unconvinced, and wrote a paper denouncing the concept in 1913. Eventually, Grossmann, Levi-Civita, Ricci, and Hilbert convinced him to accept it.

The main ideas behind relativistic covariance had already been published by Poincare and Minkowski, but they were dead by the time Einstein worked on general relativity

I believe that general covariance is a crucially important concept. It is a way of saying that the laws do not depend on coordinates. That different frames can be used to the same effect. These ideas go right to the core of why the theory is called relativity. And historically, covariance was a large part of why relativity was accepted. By 1908 it was widely accepted, even though Einstein did not.

Aaronson Starts a Venture Investing Fund

Dr. Quantum Supremacy is tired of watching his friends and associates get rich with half-baked ideas about bitcoin, quantum computing, and AI, so he is joing the gold rush. He announces:

So then, screw it! In partnership with my brother David Aaronson, who’s long done investing professionally, and on David’s guidance and encouragement, I’m hereby embarking on a new policy. ...

So far, David and I are investing in:

• Oratomic (the new neutral-atom quantum computing startup out of Pasadena started by Dolev Bluvstein, John Preskill, and Hsin-Yuan Huang among others, which I previously blogged about here). See here for their Series A announcement this week. ...

So let me educate you then. I played a central role in introducing the whole program of sampling-based quantum supremacy back in 2009-2012. That what was allowed first Google, then Quantinuum and others, to do such dramatic demonstrations starting in 2019. Almost anyone in quantum computing will tell you that that was essential to various QC startups being able to go public recently at ~$15B valuations.

Now, what’s true is that I didn’t succeed at capturing essentially any of the value that I helped create this way. What’s true is that all the billions of dollars went to other people, who optimized for getting equity early on, rather than to me or my students, who optimized for learning the truth about quantum speedups and writing the key papers that other people then managed to profit from.

This is another sign we are in a bubble.

Oratomic says that it will not try to demonstrate quantum supremacy. It will go straight for a commercial quantum computer.

The Tycho Solar System, Revisited

I always thought Tycho Brahe was the greatest pure astronomer, so I was surprised to find this new paper trashing him:

The Tychonic system, an implausible theory
Gabriele Vanin

Several scholars have accorded the Tychonic System a prominent place, considering it a credible alternative to the Ptolemaic and Copernican systems. In recent years, there have even been some enthusiastic contributions in support of Brahe, which have sought to show how his solutions were the most suitable for providing scientifics support to the new observations that were accumulating between the late 16th century and the mid-17th century.

Tycho had a model where the Sun went around the Earth, and Mercury and Venus went around the Sun.

At a time when Copernicus had already published his hypothesis, it could not but be considered a step backwards, a return to the past, a naive and useless compromise. That is, as an ad hoc theory (the kind that sci- entists gladly do without if they can, and, in this case, they could) contrived on purpose to have the best of both worlds, i.e. the immobility of the Earth and the concentric motion of the planets around the Sun, as a geometrically and physically poorly founded expedient. After Copernicus finally have the courage to declare that in the homocentric spheres, in epicycles and deferents lies hidden the orbit of the Earth, does Brahe return to the starting point, swapping the orbit of the Earth with that of the Sun again? It would be a bit as if, in the aftermath of the publication of the On the Origin of Species, someone had said that yes, evolution was acceptable, but that the evolution of man had occurred on a parallel track, not descending from the first common life-form, but from another one, completely different, and had developed quite independently.

This is ridiculous. There were good arguments for and against the motion of the Earth.

The paper later complains that Kepler's third law, discovered in 1619, could be applied to Saturns moons, discovered in 1656-84, and that would seem to falsify the Tychonic system. Tycho died in 1601.

I have seen others trash Tycho for being too stupid to accept Copernicanism. I wonder about what their idea of science is.

Tycho had the best pre-telescope astronomy observations of anyone. By far. The stars had been tracked for thousands of years, but Tycho's data was so good that it made all preceding data worthless.

A geocentric model is not necessarily wrong. Motion is relative. We say the Earth goes around the Sun, not because it is a fact, but because dynamic models make more sense in a center-of-mass frame. It makes more sense to say the smaller object is orbiting the larger object.

Tycho was creating a more accurate model of the solar system. He did not know about gravity. But without him, it is hard to see how Kepler and Newton could have accomplished what they did.

To me, science is all about collecting data, and constructing explanatory and predictive models. Tycho did this, possibly more brilliantly that any other astronomer in history. And yet people want to trash him as unscientific.

A scientific theory can be extremely good, even if the interpretation is not quite right. For example, Murray Gell-Mann is famous for his theory of quarks, but originally he did not even believe in quarks. As the quarks cannot be isolated, it is a philosophical issue whether they are real or not. Now everyone says they are real, but Gell-Mann was not really wrong to treat them as theoretical constructs.

IBM Plans to Scale Up Quantum Computing

The WSJ reports:

International Business Machines has spent a decade building, testing and improving in the once-theoretical realm of quantum computing at its glass-paneled laboratory complex in upstate New York.

This year, the company is laying the groundwork to turn that technology into a fully-fledged, scalable business from an expensive science project.

IBM said last month it plans to form a new independent subsidiary called Anderon, a foundry to produce the silicon wafers needed to make quantum-computing processors. The venture is seeded by a $1 billion investment from the Trump administration and another $1 billion of IBM’s own cash.

Anderon will give the company a new line of business in selling wafers to other quantum-computing companies. It will also provide a steady stream of wafers to continue developing its own quantum technology, positioning IBM to capture part of what the Boston Consulting Group projects will be a $90 billion to $170 billion market for quantum-computing providers by 2040.

The venture will begin with an expansion of the company’s in-house facility in Albany, N.Y., which makes wafers for IBM’s internal research. “Now we have to scale it,” IBM Director of Research Jay Gambetta said in an interview.

The company also plans to spend an additional $9 billion over five years to advance the final stages of its quest to build a quantum-mechanics-powered computer capable and reliable enough for widespread use, a goal known as fault tolerance. That computer, named Starling, is being targeted for 2029.

With Anderon, IBM is thinking beyond Starling, or even a more powerful quantum computer planned for 2033.

I don't see how IBM can be scaling up, when they do not have a working technology, and do not have applications for the scale up.

Dr. Bee has a new video trashing the prospects for quantum computing, and in particular, IBM for quietly shifting goals. It is still committed, but cannot achieve its previous goals.

Sean M. Carroll Pushes Many-worlds Again

New interview:

Quantum Mechanics Still Doesn't Make Sense | Sean Carroll
New Scientist

What really happens in the quantum world?

In this conversation, physicist Sean Carroll explores some of the deepest mysteries in quantum mechanics: the famous double-slit experiment, wave function collapse, the Many Worlds interpretation, entropy and the arrow of time.

Speaking to New Scientist reporter Jacklin Kwan, Carroll discusses why electrons appear to behave like waves, how observation seems to affect reality and whether the universe constantly branches into countless parallel worlds. Carroll also explains the measurement problem, the challenges of interpreting quantum theory and why physicists still debate what quantum mechanics is actually telling us about the nature of reality.

Carroll is a theoretical physicist, cosmologist and author whose work focuses on the foundations of physics, quantum mechanics, cosmology and the nature of time.

He gives a brief explanation of why he believes in many-worlds theory, if you want it straight from him.

He lays it out clearly. When you have a situation where several outcomes seem possible, you forget about making a prediction, and just assume that they all happen in parallel universes.

That's it. It does not really have anything to do with quantum mechanics or the Schroedinger equation. It is just a rule for replacing probabilities with unseen worlds.

You do not even get to say that some worlds are more likely than others. You just have to accept that all possibilities happen, and nothing can be predicted.

I'm a believer in the many worlds interpretation of quantum 16:58 mechanics. ... But really it's just a theory that says you want the answer to the reality problem. Wave functions are real. They represent reality precisely and completely. ...

When I observe the electron, I don't observe the wave function. I observe different possibilities. You can interpret that as saying that what the wave function really is is a superposition of all possible measurement outcomes. And what you're seeing when you measure it is you're picking out one of the set of possibilities with different probabilities. Right?

And so what many worlds ends up saying and it's not an assertion again it's it's comes out of the equations but it says that what you send up with is a superposition but not just of the electron the combined system of the electron and the scientist doing the measurement. There's a superposition of the electron was here and you observed it there plus the electron was there and you observed it there plus the electron was there and you observed it there and the many worlds boom they're there.

And so if you accept the picture of wave functions as superpositions of different measurement outcomes it's no work at all to accept them as superpositions of different possible worlds and then everything is just physics.

So you observe electrons, not wave functions. The wave function is just a way of representing all the possible observable outcomes. All that is correct. But then he makes the leap to say that "it's no work at all" to accept the possible outcomes as parallel worlds.

I spell all this out, because most readers here probably think I am attacking a straw man when I say how stupid many-worlds theory is. It really is stupid and nonsensical. Just listen to its most eloquent advocate.

It is no work at all to replace a scientific theory with one that makes no predictions. Just say that actual observables are not real, and that the real entities are the imaginary possibilities that no one ever sees. Just forget about making predictions, and brag about the explanatory power of being able to talk about unobservable parallel universes.

I continue to be amazed that anyone takes this nonsense seriously. It is impossible to reconcile this with a scientific worldview. It is the most anti-science philosophy.

Microsoft Qubits Questioned Again

Microsoft has been trying to build quantum computers with topological qubits, which would have durability advantages if they worked. But SciAm reports:

A top quantum computing expert assails Microsoft’s claims that it has a “topological qubit,” arguing in a new paper that the company has failed to demonstrate the technology.

University of St Andrews physicist Henry Legg argues that the “topological qubit,” a storer of quantum information that could theoretically maintain a higher fidelity than any in existence, might simply be noise.

The commentary was published today in Nature’s “Matters Arising,” the journal’s venue for formal criticism of its published papers. Legg’s response is aimed at Microsoft’s most recent Nature paper, which was published earlier this month—but it is just the latest in a string of criticism aimed at Microsoft’s Quantum division by other researchers in the field.

The company has been forced to retract certain previous peer-reviewed papers. And in the new commentary, Legg argues that their most recent Nature paper may be similarly flawed. In a response also published today by Nature, a member of Microsoft’s Quantum team argues that their measurements do justify the claim that they’ve produced a topological qubit.

The Microsoft paper has about 150 authors. I did not understand it. Maybe Microsoft has done some Nobel Prize quality research, but I doubt it. I wonder how the scientists convince Microsoft management to keep funding it. There is no possibility of a monetary payoff.

I did not know that Nature had a journal for formal criticism of its papers. That seems like a good idea.

Gil Kalai defends his Quantum Skepticism

Dr. Quantum Supremacy has running feuds with several people, including Israeli mathematician Gil Kalai who says in response:

When it comes to quantum computing, I regard the choice made by many colleagues and friends to pursue this direction of research as entirely (3000%) justified, and it has led to beautiful mathematics and science. (I hope that my own choice to pursue the skeptical direction was justified as well, though this is a more difficult call.)

For the record, I expect that scalable quantum computation — and even important milestones toward this goal — are inherently impossible. ...

One very clear and important point of disagreement between Scott and me concerns the following simple factual question:

Is it currently possible to produce (without classical-computing interference) samples of size 500K for depth-14 random circuits with 20 qubits and an XEB fidelity above 0.2? (This is something Google claimed in 2019.)

I tend to think that the answer to this question is negative; Scott strongly believes that this and much more have already been achieved experimentally. Thus these are sharp factual disagreements, and I hope they will be resolved within the next few years.

I do not know who is right about that factual question, but I am included to believe that Google did not really prove it, if Kalai is till unconvinced seven years later.

Aaronson is also wound up about some Middle East war issues. I understand why he is so pro-Israel, but I do not understand why he is so anti-Trump. At any rate, it is out of my expertise.