Monday, April 22, 2024

Critical Step in Quantum Networking

Researchers have produced, stored, and retrieved quantum information for the first time, a critical step in quantum networking.

The ability to share quantum information is crucial for developing quantum networks for distributed computing and secure communication. Quantum computing will be useful for solving some important types of problems, such as optimizing financial risk, decrypting data, designing molecules, and studying the properties of materials.

“Interfacing two key devices together is a crucial step forward in allowing quantum networking, and we are really excited to be the first team to have been able to demonstrate this.” — Dr. Sarah Thomas

However, this development is being held up because quantum information can be lost when transmitted over long distances. One way to overcome this barrier is to divide the network into smaller segments and link them all up with a shared quantum state.

To do this requires a means to store the quantum information and retrieve it again: that is, a quantum memory device. This must ‘talk’ to another device that allows the creation of quantum information in the first place.

For the first time, researchers have created such a system that interfaces these two key components, and uses regular optical fibres to transmit the quantum data.

There is no commercial value in this or quantum networking. No one is going to use this to optimize financial risk, design molecules, or increase the secutiry of anything.

Tuesday, April 16, 2024

Higgs has died

Physicist Lawrence M. Krauss writs:
Higgs wrote up his idea in a two-page scientific paper entitled “Broken Symmetries and the Masses of Gauge Bosons.” It was initially rejected by the major European physics journals, as having no obvious relevance to physics. But then he added a paragraph mentioning a possible observable consequence of his idea and submitted his paper to the American physics journal, Physical Review Letters, where it was published on 19 October 1964. Similar ideas were explored by the physicists Robert Brout and François Englert, and independently by Gerald Guralnik, C.R. Hagen, and Tom Kibble, and these two groups also published their work in the same journal. But, perhaps as a result of that extra paragraph that predicted a physical consequence of his theory, it was Higgs’s name that became associated with the hypothesis, which ended up providing the cornerstone of the successful effort to unify two of the four known forces in nature: the weak and electromagnetic interactions. 
CERN discovered the Higgs particle in 2012, and he got the Nobel Prize in 2013, and it ruined his life.

Okay, but I do not see why Higgs had to predict the particle, and CERN find it, for him to get the prize.

The Higgs mechanism is essential to the Standard Model, and to all the cutting edge high-energy physics since about 1970.

The other ctitical piece was tHooft's renomalization of gauge theories in about 1970. That made gauge theories the only game in town, with SU(2) for the weak and SU(3) for the strong force. 'tHooft got the Nobel Prize in 1999. He should have also gotten the prize in the 1970s, when experiments confirmed the Standard Model.

Thursday, April 4, 2024

Thank Gravitational Waves for Life reports:
Could it be that human existence depends on gravitational waves? Some key elements in our biological makeup may come from astrophysical events that occur because gravitational waves exist, a research team headed by John R. Ellis of Kings College London suggests.

In particular, iodine and bromine are found on Earth thanks to a particular nuclear process that happens when neutron stars collide. In turn, orbiting neutron star pairs inspiral and collide due to their emissions of energy in the form of gravitational waves. There may thus be a direct path from the existence of gravitational waves to the existence of mammals.

Humans are mostly made up of hydrogen, carbon and oxygen, with many additional trace elements. (There are 20 elements essential to human life.) Those with an atomic number less than 35 are produced in supernovae, implosions of stars that have exhausted their nuclear fuel and collapsed inward. The collapse results in an explosion that spews their atoms all over the universe.

But two elements are provided by other means—iodine, needed in key hormones produced by the thyroid, and bromine, used to create collagen scaffolds in tissue development and architecture. ...

Ellis and his colleagues calculate that the r-process has provided 96% of the abundance of 127I on Earth, an isotope essential for human life, and most of the abundance of bromine and gadolinium in the Earth's crust, plus all of the Earth's thorium and uranium and a fraction of the molybdenum and cadmium.

Seems farfetched, but interesting anyway. Here is the paper.

Update: Dr. Bee comments.

Monday, April 1, 2024

Sapolsky and Sam Harris on Free Will

Imagine that two schizophrenic have a discussion about hearing voices in their heads. They both agree that they hear voices, but then puzzle about how hard it is to convince others that the voices are real.

I used to thinjk that the anti-free-will advocates could not possibly believe what they are saying. Ordinary life requires making choices. Why do they get out of bed in the morning?

That is what this podcast is like:

We Really Don’t Have Free Will?: A Conversation with Robert M. Sapolsky (Episode #360)

Sam Harris speaks with Robert Sapolsky about the widespread belief in free will. They discuss the limits of intuition, the views of Dan Dennett, complexity and emergence, downward causation, abstraction, epigenetics, predictability, fatalism, Benjamin Libet, the primacy of luck, historical change in attitudes about free will, implications for ethics and criminal justice, the psychological satisfaction of punishing bad people, understanding evil, punishment and reward as tools, meritocracy, the consequences of physical beauty, the logic of reasoning, and other topics.

Robert M. Sapolsky is the author of several works of nonfiction, including A Primate’s Memoir, The Trouble with Testosterone, Why Zebras Don’t Get Ulcers, and most recently, Determined: A Science of Life without Free Will. His book titled Behave was a New York Times bestseller and named a best book of the year by The Washington Post and The Wall Street Journal. He is the John A. and Cynthia Fry Gunn Professor of biology, neurology, and neurosurgery at Stanford University and the recipient of a MacArthur Foundation “Genius Grant.” He and his wife live in San Francisco.

Okay, I am satisfied that some schizophrrenics hear voices in their heads, and Sapolsky and Harris have some other disorder controlling their brains. They adamantly argue that they have no choices in what they do.

Believe in free will or not as you please, but there is no law of Physics that requires the future to be determined by the past.

Thursday, March 28, 2024

“Don’t be a monkey!”

Lawrence M. Krauss writes:
I vividly remember the first time he showed me his famous video of capuchin monkeys—later to feature in a TED talk that has 23 million views and counting — in which two capuchin monkeys, kept in adjoining cages, are fed treats for exhibiting a certain behaviour. The monkeys were perfectly happy performing their task for cucumbers until, one day, one of the monkeys was rewarded with a grape instead. When the monkey’s companion was given a cucumber for the same task, he immediately proceeded to throw a temper tantrum worthy of a three-year old child — even though, five minutes earlier, he had been content with that reward. 

I immediately recognized the behaviour in myself! I showed the video to my wife, and ever since then, whenever I start to feel envious of someone for receiving any sort of reward that appears to be greater than that which I had previously been perfectly happy to receive during a similar experience, I tell myself, or my wife tells me: “Don’t be a monkey!”

He vividly recalls this, because he watched a cherry-picked video. You can read more in the Wikipedia article on Inequity aversion in animals.

The experiment has been repeated many times, with mixed results. Female (but not male) capuchin monkeys showed the effect, and so did some other species. Many experiments failed to find the effect.

I think the most interesting part of this is watching humans, like Krauss, watch this video and interpretation, and somehow think that they know what is going on inside the monkey's mind. I think they are projecting their own views onto the monkeys.

It is not clear that the monkey is feeling envy, or disapproval of the inequitable reward. If the monkeys were really rejecting inequity, then maybe the monkey getting the grape would give it to the other monkey. No, that does not happen.

It is hard to see how this says anything about cooperation, as these monkeys are lousy at cooperating on anything.

As for envy, it is not clear that the monkey cares at all what the other monkey is getting. Maybe the monkey notices that she could be getting a grape, and then rejects the lesser reward in order to get the grape. Indeed, this experiment has been done with just one monkey, and it just shows that the monkey wiil show that it wants the better reward.

I just tried showing the video to a ten-year-old boy, and asked him what he saw. He said, "i see a monkey who wanted a grape." When I explained that the grownup scientist interpreted this as a monkey protesting pay unfairness, he looked puzzled, and did not see why anyone would think that.

The TED Talk has a slide saying the Pillars of Morality are Reciprocity/Fairness and Empathy/Compassion. This is a very left-wing view that I call Kindergarten Morality. Kindergarten teachers commonly tell kids that they all have to share the toys equally, and show compassion to all. Older kids usually understand that such equality is impractical, and other moral concepts are more important. For more on how leftists have crippled moral outlooks, see Jonathan Haidt's Moral foundations theory.

Monday, March 25, 2024

Stealing our cutting edge String Theory

Eric Weinstein tweeted:
Q: How do you know that String Theory isn’t working as physics despite expert assurances to the contrary?

A: No one at all is in any way worried about the Iranians, Russians or Chinese getting their hands on our cutting edge String Theory.

Ha ha. Do they worry about enemies stealing our fusion reactor or quantum computer technology? Maybe a little bit.

Our semiconductor, rocket, and AI technology? A lot.

Weinstein has his own pet theories to replace the Standard Model of high-energy physics, but it has gone nowhere.

Update: Here is a video clip with more from him and Lee Smolin. Smolin also has his pet theories that have gone nowhere. Their complaint is not just that string theory does not work, but that it gets more attention than other thoeries that do not work.

For someone negative on the whole high-energy research program, see Unziger.

Monday, March 18, 2024

Deutsch defends Many-Worlds Theory

New podcast: The Multiverse is REAL - David Deutsch.

He says the double-slit experiment conclusively proves the many-worlds theory. He accepts the parallel worlds for the same reason he accepts the existence of dinosaurs (millions of years ago). It is the only way to explain the evidence.

He admits that the photons are not really particles, and that any waves show a similar diffraction pattern. But he says that for the photon to behave as a wave, it must exist in multiple copies.

He also admits that all this has been known for decades, and yet most physicists do not accept this argument for many-worlds.

I do not see any merit to this argument. The double-slit experiment only proves that light, and other beams like electron beams, have wave properties. That's all. It is not even evidence for quantum mechanics, as this wave explanation was accepted before quantum mechanics was invented.

When asked about alternative theories, he says the von Neumann had this crazy idea that if you observe an electron in one place, then the possibility of it being somewhere else ceases to exist.

I do not see the problem with that. I do not even think the issue has anything to do with quantum mechanics. Anytime you estimate the probability of an event, and then observe it, that means that the other possibilities did not happen. That is how probabilities work.

He pushes quantum computing, but admits that he has not followed the latest technology.

I see the argument for many-worlds as nothing more than a rejection of probability theory. You could take any scientific theory that predicts probabilities, deny that the probabilities make any sense, and conclude that there are parallel worlds of unobserved possibilities.

That is all many-worlds theory is. I don't think that it even has anything to with quantum mechanics. It is only expressed in terms of quantum mechanics, because textbook QM emphasizes the probabilities. But other theories use probabilities the same way, and could have many-worlds interpretations.

Many-worlds thsoey is just the same as taking a science textbook, announcing some philosophical disagreement with probability theory, and redacting all the sections mentioning probability. It adds nothing. It just removes the theory's predictive power.

It is hard to see how any intelligent man takes many-worlds seriously. It offers nothing. Maybe they just don't understand probability theory, as I do not see anywhere that they recognize that they are just rejecting probability.

PBS TV has a news item:

How quantum computing could help us understand more about the universe

Scientists, researchers and some big companies are eager to jumpstart the next generation of computing, one that will be far more sophisticated and dependent on understanding the subatomic nature of the universe. But as science correspondent Miles O’Brien reports, it’s a huge challenge to take this new quantum leap forward.

A lot of hype. They admit that a fault tolerant quantum computer might be decade away. No one admits that it might be impossible.

Monday, March 11, 2024

Physics v. Magic

From xkcd comics.

His point here is that Physics is inherently causal. Things happen because there is some causal sequence of interactions from event A to event B, when A causes B.

For example, the Sun's gravitational pull on the Earth was once thought to be action-at-a-distance, but is not thought of as the Sun perturbing spacetime and a wave traveling to Earth. Or gravitons traveling to Earth.

However Physics often reasons from results, without following a causal chain. Examples are thermodynamics, conservation laws, and Lagrangians.

There are also examples in quantum mechanics. A particle might tunnel through a wall, without any understanding of how it gets through the wall.

In spite os these example, I still believe the universe is inherently local, in cause and effect. Sometimes our reasoning can skip some steps, but only as a mathematical convenience. There is no action-at-a-distance, and no magic.

Monday, March 4, 2024

Poincare was Five Years ahead of Einstein

It is funny to see historians try to credit Einstein. Here is a 2013 essay I had not seen before:
On some points, such as the principle of relativity or the physical interpretation of the Lorentz transformations, Poincaré’s contributions preceded by at least 5 years those of Einstein’s published in 1905. On the other hand, many of their contributions were practically simultaneous. In 1905 Poincaré published an abridged version of his “Sur la dynamique de l’électron” [3] (which preceded the work of Einstein); the expanded version of the article appeared in 1906 [4].

What are the conceptual differences? According to Darrigol,

Einstein completely eliminated the ether, required that the expression of the laws of physics should be the same in any inertial frame, and introduced a “new kinematics” in which the space and time measured in different inertial systems were all on exactly the same footing. In contrast, Poincaré maintained the ether as a privileged frame of reference in which “true” space and time were defined, while he regarded the space and time measured in other frames as only “apparent.” …Einstein derived the expression of the Lorentz transformation from his two postulates (the relativity principle and the constancy of the velocity of light in a given inertial system), whereas Poincaré obtained these transformations as those that leave the Maxwell–Lorentz equations invariant [1].
These are conceptual differences that have no actual experimental consequences as far as electromagnetism and optics are concerned. As Lorentz commented, the difference is purely epistemological: it concerns the number of conventional and arbitrary elements that one wishes to introduce in the definitions of the basic physical concepts.

Are we then dealing with a case of simultaneous discovery?

No, it was not simultaneous. Poincare was five years ahead of Einstein. Poincare was years ahead of Einstein with the relativity principle, rejection of the aether, local time, synchronizing clocks, interpreting Michelson-Morley, Lorentz group, mass-energy equivalence, four-dimensional spacetime, and relativistic theories of gravity. Einstein's only claim to originality is to certain epistemological differences of no physical significance.

Credit Einstein with those obscure conceptual differences if you want, but there is no mathematical or physical value to any of them. Mostly they consist of mathematical misunderstandings by Einstein and other physicists. For example, there is nothing erroneous about choosing a privileged frame on a symmetric space. It does not break the symmetry. Those who criticize Poincare for occasionally choosing a privileged frame are just mathematically ignorant.

The essay concludes:

As Darrigol suggests, it seems wiser to concede that Lorentz, Poincaré and Einstein all contributed to the emergence of the theory of relativity, that Poincaré and Einstein offered two different versions of the theory, and that Einstein gave form to what today is considered the best one.
No, Einstein's is not considered best today. Nearly everyone prefers the spacetime formulation that Poincare advanced in 1905 and Minkowski perfected in 1907. Einstein was still rejecting it in 1911, and did not even speak positively about it until after that, and never really accepted the geometrical significance.

A lot of historians concede that Lorentz and Poincare had all the mathematics of special relativity, and all the physical consequences, but insist that Einstein had a more modern viewpoint or superior understanding, leading to how we understand the theory today. But that is false. The Poincare-Minkowski geometrical interpretation has been preferred by nearly everyone but Einstein, since 1908.

Saturday, February 24, 2024

Thursday, February 22, 2024

Chinese Deflate Quantum Hype Again

Sabine Hossenfelder is now doing short daily physics news videos, and her latest is on Bad News for Quantum Computing: Another Advantage Gone.

In short, quantum computing researchers have been claiming quantum supremacy for years. Some call it quantum advantage. However, there has never been any convincing demonstration that quantum computers have any speedup at all over conventional computers.

The latest is that IBM claimed last year to do a quantum calculation on a "noisy" quantum computer. Some thought that they had outdone Google. But a Chinese group outdid them by doing the calculation faster and better on a classical computer.

The quantum enthusiasts will argue, as usual, that this does not disprove quantum computing, and maybe a more clever experiment would show an advantage. I am waiting.

Monday, February 12, 2024

The physicists philosophy of physics

Princeton astrophysicist PJE Peebles writes:
The starting idea of the natural sciences is that the world operates by rules that can be discovered by observations on scales large or small, depending on what interests you. In fundamental physics, the subject of this essay, the idea is narrowed to four starting assumptions.

A: The world operates by rules and the logic of their application that can be discovered, in successive approximations.

B: A useful approximation to the rules and logic, a theory, yields reliably computed quantitative predictions that agree with reliable and repeatable mea- surements, within the uncertainties of the predictions and measurements.

C: Fundamental physical science is growing more complete by advances in the quantity, variety, and precision of empirical fits to predictions, and by occa- sional unifications that demote well-tested fundamental physical theories to useful approximations to still better theories.

D: Research in fundamental physical science is advancing toward a unique mind-independent reality.

These sound reasonable, but they leave no room for many-worlds theory, string theory, simulation hypothesis, superdeterminism, or many of the ideas that are now fashionables.

The essay gives way too much attention to philosopher Thomas Kuhn.

It quotes Einstein:

The supreme task of the physicist is to arrive at those universal elemen- tary laws from which the cosmos can be built up by pure deduction.
This sounds a little like Weinberg's mythical Final Theory, also discussed.

No, trying to build the cosmos from pure deduction is foolishness.

Thursday, February 8, 2024

Dissecting Einstein's Brain

The RadioLab podcast just rebroadcast this:
Albert Einstein asked that when he died, his body be cremated and his ashes be scattered in a secret location. He didn’t want his grave, or his body, becoming a shrine to his genius. When he passed away in the early morning hours of April, 18, 1955, his family knew his wishes. There was only one problem: the pathologist who did the autopsy had different plans.

In the third episode of “G”, Radiolab’s miniseries on intelligence, we go on one of the strangest scavenger hunts for genius the world has ever seen. We follow Einstein’s stolen brain from that Princeton autopsy table, to a cider box in Wichita, Kansas, to labs all across the country. And eventually, beyond the brain itself entirely. All the while wondering, where exactly is the genius of a man who changed the way we view the world?

Later in the show, it discussed theories for the origin of Einstein's most brillian idea -- special relativity. Besides his extra-smart brain, it mentioned his physicist wife and a philosopher. It even had professor Galison explaining how train schedules causes people to rethink time.

Okay, but there was no mention of Lorentz and Poincare, or the fact that they had published the entire theory ahead of Einstein.

Galison is unusual because he does not recite crazy stories about Einstein's originality, like other Einstein scholars. He read Lorentz and Poincare and obviously understands that they did it all first, but he refuses to comment on the priority dispute.

Monday, February 5, 2024

What's the difference, said Heisenberg

From a math site:
In the 1960s Friedrichs met Heisenberg and used the occasion to express to him the deep gratitude of mathematicians for having created quantum mechanics, which gave birth to the beautiful theory of operators on Hilbert space. Heisenberg allowed that this was so; Friedrichs then added that the mathematicians have, in some measure, returned the favor. Heisenberg looked noncommittal, so Friedrichs pointed out that it was a mathematician, von Neumann, who clarified the difference between a self-adjoint operator and one that is merely symmetric. "What's the difference," said Heisenberg.

- story from Peter Lax, Functional Analysis (slightly edited for length)

There is the difference between a physicist, and a mathematical physicist.

John von Neumann wrote a 1932 book on quantum mechanics, and turned it into a real theory.

To a physicist, an observable is a symmetric operator, because those are the ones that give real values, and only real values are observed. To von Neumann, an observable is a self-adjoint operator on a Hilbert space, where some additional technical requirements are needed in order to prove the spectral theorem.

I am not trying to say that Heisenberg was stupid. But it is striking that a world-famous physicist could get a Nobel Prize for using operators as observables, and still be oblivious to the formal mathematical definition found in textbooks. We cannot expect physicists to understand mathematical subtleties.

Thursday, February 1, 2024

The World is not Discrete

Some people like to say that Quantum Mechanics makes the world discrete. That is not true. But I always assumed that QM models could be approximated by lattice models.

Apparently this is not true. We know that the weak force is chiral, ie, it violates mirror reflection symmetry. Neutrinos are left-handed in the Standard Model.

From the Scott Aaronson blog:

“There is currently no fully satisfactory way of evading the Nielsen-Ninomiya theorem. This means that there is no way to put the Standard Model on a lattice. On a practical level, this is not a particularly pressing problem. It is the weak sector of the Standard Model which is chiral, and here perturbative methods work perfectly well. In contrast, the strong coupling sector of QCD is a vector-like theory and this is where most effort on the lattice has gone. However, on a philosophical level, the lack of lattice regularisation is rather disturbing. People will bang on endlessly about whether or not we live “the matrix’”, seemingly unaware that there are serious obstacles to writing down a discrete version of the known laws of physics, obstacles which, to date, no one has overcome.”
There is a whole industry of physicists doing lattice approximations to the SM, but the SM is chiral and the approximations are not, so there is no hope that the approximations converge to the SM.

Aaronson is commenting on the silly idea that we live in a computer simulation. If we did, it would raise another silly idea that we could overwork the simulator by doing certain experiments.