Friday, January 27, 2023

NY Times on Where Physics is Headed

Peter Woit reports:
The New York Times today has Where is Physics Headed (and How Soon Do We Get There?). It’s an interview by Dennis Overbye of Maria Spiropulu and Michael Turner, the chairs of the NAS Committee on Elementary Particle Physics – Progress and Promise. This committee is tasked with advising the DOE and NSF so they can “make informed decisions about funding, workforce, and research directions.”
Turner: But it is a powerful mathematical tool. And if you look at the progress of science over the past 2,500 years, from the Milesians, who began without mathematics, to the present, mathematics has been the pacing item. Geometry, algebra, Newton and calculus, and Einstein and non-Riemannian geometry.
He probably meant "Einstein and non-Euclidean geometry" or "Einstein and Riemannian geometry". Technically, general relativity metric are indefinite and not Riemannian, so he could have mean non-Riemannian. However Rimannian geometry was the math that Einstein and Hilbert used for the field equations.
Among the many features of string theory is that the equations seem to have 10⁵⁰⁰ solutions — describing 10⁵⁰⁰ different possible universes or even more. Do we live in a multiverse?

Turner:

I think we have to deal with it, even though it sounds crazy. And the multiverse gives me a headache; not being testable, at least not yet, it isn’t science. But it may be the most important idea of our time. It’s one of the things on the table. Headache or not, we have to deal with it. It needs to go up or out; either it’s part of science or it isn’t part of science.
If it is not testable, and not part of science, why do we have to deal with it? They are just solutions to some equations that have no known relationship to the real world.

Wednesday, January 25, 2023

PBS Nova: Einstein's Quantum Riddle

PBS TV Nova has a new documentary on Einstein's Quantum Riddle, free on PBS and YouTube.

It is all about entanglement as the fundamental mystery of the universe.

I think it is entirely wrong. As noted before, entanglement is not so different from classical physics.

It argues that entanglement can be used to improve communications security, because the encryption relies on the laws of physics.

Monday, January 9, 2023

Carroll and Coyne Against Free Will

Jerry Coyne and Sean M. Carroll posted new rants on free will.

Maybe I am stupid, but these guys don't make much sense to me. Carroll says he believes in free will, but he is also a determinist, and thinks it is theoretically possible to develop technology to predict everything your brain will do. If so, you won't have free will. But that will probably never happen, so you can think of yourself as having free will as a way of coping with everyday life.

In other words, free will is an illusion.

Coyne is more against free will.

[reader comment] According to your theory, the “sane” person should never be found guilty of a crime

[Coyne] Oh for crying out loud, you haven’t followed my writings on this at all. There are very good reasons to convict sane people of a crime: to keep them away from society, to reform them, and to act as a deterrent. Go read “free will” post on this site before you make remarks like that.

That answer might make sense if the judge has free will and the criminal does not. But if no one has any free will, what is the point of giving any reasons for doing anything? It is all pre-determined, so just sit back and enjoy the ride. Nothing you or the judge decide will make any difference.

Here is more:

[reader] Your comments make perfect sense from within the materialist/determinist paradigm, but I also think it points out why the materialist/determinist paradigm is just as incoherent as any other theory of consciousness.

1. Is it actually possible to live consistently within the idea that no one chooses any thought they hold? That would render much of Professor Coyne’s popular life work moot. Why try and convince people of the futility of religious or creationist beliefs of the could not have believed otherwise?

[Coyne] 1. I do live that way. Also, even thought what I wrote may have been determined, it can still change people’s minds, because it is an environmental factor that can influence other people. Saying that determinism makes my work is not only incoherent in itself, but, frankly, offensive. I don’t CARE if I was determined to write what I did. I’m happy to know that I’ve changed people’s minds, which I have.

[reader] 1. I have often felt a serious blind spot by those who call themselves determinists is their unwillingness to give up popular folk notions of personal responsibility. It is an incompatibility to say that our thoughts and behaviors are determined but people who I disagree with can change their positions. I don’t think appealing to any intermediary step such as environment helps as that step will be just as determined. All ideas have consequences and determinism has them for our everyday notions of law and morality.

[Coyne] This is the last bit of the exchange; we’re done.

1. There is no incompatibility. If you kick a friendly dog because you were determined by the circumstances or your personality to do that, the dog will eventually shy away [from] you. Determinism plus behavior change. No problem. You appear to be confused. I’ve already discussed what I mean by “personal responsibility”: Person X did thing Y. Person X is therefore responsible for having done Y. You know this so why is this an issue?

I say humans have more personal responsibility than a dog because of consciousness and free will. Not sure what Coyne is saying. If he is not capable of changing his own mind, then I don't know why he thinks that he can change someone else's mind. If people are just like dogs who have been kicked, then I don't know why they would have personal responsibility.

I have a similar issue with Sam Harris. He is always talking about how no one has free will, and he does not even have the feeling of free will. And yet he spends the rest of his time trying to persuade people of various moral stances. Makes no sense to me.

Here is Carroll on many-worlds, from his blog in 2015:

The particular objection I’m thinking of is:

MWI is not a good theory because it’s not testable.

It has appeared recently in this article by Philip Ball — an essay whose snidely aggressive tone is matched only by the consistency with which it is off-base. Worst of all, the piece actually quotes me, explaining why the objection is wrong. So clearly I am either being too obscure, or too polite.

I suspect that almost everyone who makes this objection doesn’t understand MWI at all. This is me trying to be generous, because that’s the only reason I can think of why one would make it. In particular, if you were under the impression that MWI postulated a huge number of unobservable worlds, then you would be perfectly in your rights to make that objection. So I have to think that the objectors actually are under that impression.

An impression that is completely incorrect. The MWI does not postulate a huge number of unobservable worlds, misleading name notwithstanding. (One reason many of us like to call it “Everettian Quantum Mechanics” instead of “Many-Worlds.”)

Now, MWI certainly does predict the existence of a huge number of unobservable worlds. But it doesn’t postulate them. It derives them, from what it does postulate.

Got that? He says it would be reasonable to object to many-worlds if you thought it postulated many worlds. But it actually postulates something equivalent to many-worlds, and then derives the many worlds. He says this misunderstanding "saddens me, as an MWI proponent". 

Sorry, but it is a mathematical fact that if you postulate something that implies many-worlds, then you are postulating many-worlds.

A review notes:
Carroll echoes Everett in contending that the key mathematical expression in quantum physics, known as the wave function, should be taken seriously. If the wave function contains multiple possible realities, then all those possibilities must actually exist. As Carroll argues, the wave function is “ontic” — a direct representation of reality — rather than “epistemic,” a merely useful measure of our knowledge about reality for use in calculating experimental expectations. In epistemic interpretations, “the wave function isn’t a physical thing at all, but simply a way of characterizing what we know about reality.”
So once he postulates the equivalent of many worlds, he insists that they are real. No, imaginary unobservable things do not become real by postulating them (or antecedents of them).

Saturday, January 7, 2023

Why you can buy a Bobble-head Einstein

This week's Sabine Hossenfelder video is on Special Relativity: This Is Why You Misunderstand It.
The most important part of Einstein's theories is that they combine space and time into one common entity, space-time. This idea didn't come from Einstein but from Minkowski, but Einstein was the one to understand what itmeans. Which is why today you cany buy a bobble-head Einstein but not a bobble-head Minkowski. Sorry Minkowski.
No, the idea came from Poincare's 1905 paper, and further developed by Minkowski in 1907. Einstein missed it in his papers, and even admitted:
Since the mathematicians have invaded the theory of relativity, I do not understand it myself anymore.
Almost everything she says was from Poincare and Minkowski, and not even understood by Einstein until around 1915. She adopts a modern geometrical interpretation that Einstein rejected most of his life.

Monday, January 2, 2023

Textbooks get Plum Pudding Wrong

A couple of Norway professors write:
Most physics textbooks at college and university level introduce quantum physics in a historical context. However, the textbook version of this history does not match the actual history.
Their main complaints are about textbook descriptions of the Plum pudding model and Rutherford model. In particular, the textbooks say that Rutherford introduce unstable electron orbits into Thomson's plum pudding model. This is incorrect. Wikipedia explains:
The Rutherford model served to concentrate a great deal of the atom's charge and mass to a very small core, but didn't attribute any structure to the remaining electrons and remaining atomic mass.
The electron orbits had already been proposed by Thomson and others, and Rutherford was only concerned with the nucleus.

I am glad to see this paper "exposing the flaws in the textbook version of the historical development of quantum theory", but there is no mention of Wikipedia. The paper is organized about the confusion of a hypothetical girl Emma who reads Gamow's 1966 book but not Wikipedia.

Physics textbooks love to tell these simplified historical stories. Such as how Galileo dropped two rocks from the Leaning Tower of Pisa and proved Aristotle wrong. Usually the true story is just as good, and more instructive.

Actually, Galileo never dropped anything from the Pisa tower, and Aristotle did not say heavy objects fall faster.