Wednesday, January 22, 2020

The future is not the past

I just heard this on NPR Radio:
SEAN CARROLL: To a physicist, time is a label on the universe.

RAZ: Sean Carroll is a theoretical physicist.

CARROLL: At CalTech.

RAZ: And physicists like Sean think about time very differently from you and me.

CARROLL: To a physicist, the universe is this thing, it's full of stuff, and it keeps happening over and over again. And this goes back to, you know, ancient astronomers. The Earth revolves around the sun, and it rotates around its axis 365 times. So the universe is filled with repetitive, cyclic moments, and time is just the label on those different moments.

RAZ: Those labels - one day, one month, one year - make up what Sean and other physicists call the arrow of time, meaning that time travels in one direction. That's why you were younger in the past, while you'll be older in the future, why you remember one and not the other. But here's the problem. That difference between past and future is nowhere to be found in the laws of physics because in physics, there is no arrow of time.

CARROLL: When modern physics came to be from people like Galileo and Newton up through Einstein, we realized something very gradually, which is that the deep down laws of physics don't distinguish between the past and the future. They treat them completely symmetrically as if they were just replaceable with each other. So as a physicist, there's almost more work to be done in understanding why time works the way it does than as a person on the street because you have to reconcile the fact that there is a difference between past and future with the fact that that difference doesn't appear anywhere in your fundamental equations.

RAZ: In the laws of physics, there is no intrinsic difference between the past and the future.

CARROLL: That is exactly right.

RAZ: Which theoretically means what?

CARROLL: So if you think about time going from the far, far, far past - let's say the Big Bang was not the beginning. Let's say there was sort of an infinite amount of time before the Big Bang, and there's an infinite amount of time after the present moment. It's possible there are regions of the universe where their notion of past and future are backwards compared to ours, where they call the past what we call the future and vice versa. That's completely allowed because the underlying laws of physics don't distinguish.
It appeared to be a rerun from 2015.

I don't know how a Caltech physicist can say such nonsense. He later acknowledges that entropy is increasing with time, but he argues that is just because the Big Bang was low entropy.

Of course the laws of physics distinguish past from future.

Monday, January 20, 2020

Carroll rejects panpsychism

Jerry Coyne agrees with Sean M. Carroll about panpsychism failing to explain consciousness:
Goff himself, in the podcast below, repeatedly states that he’s “heartened” by the increasing (but still minority) view among philosophers that panpsychism is the way to go in explaining consciousness. And others, like physicist Lee Smolin, authors Annaka Harris and Philip Pullman, and philosopher Stephen Law, have endorsed Goff’s new trade book, though this doesn’t mean they all endorse panpsychism. ...

Sean, of course, is a physicist, cosmologist, and author, who knows a lot about philosophy. Debating him is Philip Goff, a philosopher at Durham University and perhaps the most vociferous advocate of panpsychism (he has a new book about it). Sean states from the outset that he doesn’t accept panpsychism, and that materialism (his view of the world) is perfectly capable of explaining consciousness, though it’s a hard problem and will take a long time to understand. ...

A brief view of the controversy. Goff avers that materialism won’t help us understand consciousness because all it produces are correlations between brain activity and conscious experience. That, he says, is useless because it doesn’t enable us to get at the heart of consciousness: subjective experience or “qualia”. As he says, “How can you capture in an equation the spiciness of paprika?” ...

In response to Goff’s statement that we need to know what consciousness really is,  Carroll answers he doesn’t really care about the “intrinsic nature of subjective experience”. If you have consciousness and know how it’s produced from neurons and the brain, that’s all there is to know.

As I said, the heart of the disagreement starts about 71 minutes in, when Goff argues that yes, everything is conscious: even the mass, spin, and charge of physical particles like electrons are forms of consciousness: a “limited form of conscious experience.” But that’s about as far as he goes in defining consciousness of inanimate objects. When Carroll asks him if he means that everything is conscious, because everything has physical properties, and whether the the Universe’s wave function is also conscious (Sean talks about that wave function his latest book Something Deeply Hidden), Goff gives a reluctant “yes”. Goff also declares that panpsychism is completely congruent with what physics tell us about the Universe. 
Before the discovery of DNA, people wondered whether life could be reduced to chemistry. We do not know whether consciousness can be similarly reduced.

SciAm also has an article on panpsychism.

It is funny to see these guys argue about who is being more materialist.

Coyne and Carroll do not even believe in free will, so they must have a very limited view of consciousness. What is consciousness, if not the ability to come to your own conclusions about yourself and the world? If they don't believe in that, they I say they don't believe in consciousness.

I am not sure it makes sense to say that electrons have a tiny bit of consciousness, but I am not sure it is any crazier than someone thinking a century ago that a single DNA molecule could contain the mystery of life, in coded form.

I hate to see mainstream science popularizers promoting their personal speculations as if they were scientific facts.

Jerry Coyne argues:
Like Massimo, I’m perplexed, because when you ask Goff to tell us in what sense electrons are “conscious”, he just redefines their properties — spin, mass, charge, and so on — as consciousness. But if you pull that trick, then explaining human consciousness just becomes a purely physical problem, given Goff’s addendum that when you bundle enough conscious atoms and molecules and neurons together, you get a human brain. In other words, why isn’t consciousness then an epiphenomenon of the collection of molecules that make up the brain?

Further, Goff seems to think there is some “intrinsic nature” of matter that isn’t given by its behavior and observable properties. But to a physicist, the described properties of an electron completely characterize an electron for any purpose that we want. And if you call those properties “consciousness” and say that when there are enough conscious particles in a lump you get “higher” humanlike consciousness, then you’re saying nothing beyond describing neuroscientists are already trying to do. There are no essences beyond what we can observe. Or, if there are, Goff can’t tell us what they are, though he strains mightily to do so.
No, the electron is not completely characterized by mass, charge, and spin.

To see why, just read this new SciAm article on double-slit and triple-slit experiments. As it explains, photons and electrons give interference patterns that cannot be understood from just the quantum numbers of the particles. Indeed, the patterns disappear if you put detectors in the slits.

Quantum mechanics uses wave functions to predict these interference patterns, and the wave function have info that goes far beyond the quantum numbers. Because the theory is so successful, many are tempted to say that the wave function completely characterizes the electron. But we don't know that. The wave function is not observable, and we are almost never sure that we even have the right wave function.

Textbooks sometimes say that the electron is completely characterized by mass, charge, and spin, because there is a quantum theory of identical particles. All electrons are identical in the sense that if you have a lot of them in a system, there is a symmetry that applies to them. The symmetry has experimental consequences, so we are very confident about it. I am not disputing that.

But the wave function encodes other info, such as position, momentum, and entanglement with other particles. The wave function successfully predicts experiments, but physicists commonly complain that it is not telling us the whole story.

So based on current physics, it is possible that an electron has some infinitesimal consciousness.

A philosopher law professor suggests that panpsychism is the most preposterous of currently fashionable philosophical views. He links to a poll comparing it to other supposedly-preposterous views, like free will. I am sure that philosophers have much more preposterous views than these!

Thursday, January 16, 2020

Theoretical Physics has lost its way

Physicist Sabine Hossenfelder writes:
In the foundations of physics, we have not seen progress since the mid 1970s when the standard model of particle physics was completed. Ever since then, the theories we use to describe observations have remained unchanged. Sure, some aspects of these theories have only been experimentally confirmed later. The last to-be-confirmed particle was the Higgs-boson, predicted in the 1960s, measured in 2012. But all shortcomings of these theories – the lacking quantization of gravity, dark matter, the quantum measurement problem, and more – have been known for more than 80 years. And they are as unsolved today as they were then. ...

Instead of examining the way that they propose hypotheses and revising their methods, theoretical physicists have developed a habit of putting forward entirely baseless speculations. Over and over again I have heard them justifying their mindless production of mathematical fiction as “healthy speculation” – entirely ignoring that this type of speculation has demonstrably not worked for decades and continues to not work. There is nothing healthy about this. It’s sick science. And, embarrassingly enough, that’s plain to see for everyone who does not work in the field. ...

Why don’t physicists have a hard look at their history and learn from their failure? Because the existing scientific system does not encourage learning. Physicists today can happily make career by writing papers about things no one has ever observed, and never will observe. This continues to go on because there is nothing and no one that can stop it.
She is right. Complaints about the quantum measurement problem or quantum gravity are commonplace, but we are right where we were many decades ago.

Dr. Bee is never going to get tenure anywhere, as physicists do not like to hear this.

The Economist mag has an article about how physicists want to build a new particle collider, but the outlook is bleak for new physics:
As Jon Butterworth, a member of the team that discovered the Higgs boson in 2012, puts it, “My whole career there’s been a very clear road map of what we need to do next and now there isn’t one. We’ve outgrown our road map. Experiment is ahead of the theory. It’s an interesting and difficult time.”
It would be nice is a new accelerator brought us some new physics, but it is a fantasy.

Tuesday, January 14, 2020

More funding for quantum computing

NextGov reports:
The Energy Department pledged up to $625 million to help stand up two to five multidisciplinary quantum information science research centers between now and 2025.

According to a funding opportunity announcement launched Friday, the agency will abide by a mandate set forth in a 2018 law to support the creation of several QIS centers to expedite revolutionary advances in science and quantum-based technology — and ultimately continue to secure the United States’ position at the forefront of the global quantum computing landscape.

"Critical to America's leadership in this field, the new quantum research centers provide training and collaboration opportunities for the next generation of QIS scientists and engineers,” Ivanka Trump, the president’s adviser and daughter, said in a statement. She went on to thank Energy for working to strengthen America’s “competitiveness in this industry of the future."

President Trump signed the National Quantum Initiative Act over a year ago, which helped catalyze a range of federal investments and industry advancements in QIS. On top of requiring coordinated, multi-agency efforts to boost QIS research and training, the law also called for the establishment of four to ten competitively awarded QIS research centers. Energy Secretary Dan Brouillette said in a statement Friday that the agency wants to help “ensure that America remains a world leader in this rapidly advancing field.”
Nobody wants to say that this is a boondoggle.

Thursday, January 9, 2020

Black hole information is just philosophy

Physicist Coel is a big believer in science being able to answer all questions, he writes in a review of a philosophy ook:
But, equally, theoretical physicists don’t work with laboratory equipment, taking measurements, they work with ideas and concepts. The internal coherence of concepts about the world is just as much a concern for scientists as for philosophers.

A current example is the black-hole information paradox, where the paradox is that current models of black holes suggest that “information” (which itself is a highly abstract concept, not a direct observable) is destroyed when material falls into a black hole. And yet, a basic principle of quantum mechanics (the best theory of matter, thought to apply everywhere) says that information can never be destroyed. Trying to resolve the inconsistency is currently exercising many of the world’s top theoretical physicists, partly because the solution might point the way to a model of “quantum gravity”, the long-sought unification of quantum mechanics with general relativity. Yet this activity is entirely conceptual, since observations and experiments pertaining directly to the issue are way beyond current capabilities. Physicists still regard the enquiry as “scientific”, even if some philosophers might want to declare it to be “metaphysics”.
This is such a terrible example. Because information is such an abstract concept, we don't know if it is destroyed in a black hole or anywhere else.

Also, conserving information is not described as a basic principle of quantum mechanics in any textbook I have.

And there is no possibility that resolving this supposed paradox will ever have anything to do with quantum gravity.

Monday, January 6, 2020

Everettian QM makes no predictions

Sean M. Carroll is a big proponent of many-worlds theory, having just written a book about it. The physics part of it is demolished by a new paper:
Epistemic separability and Everettian branches --- a critique of Sebens and Carroll

by Dawid, Richard and Friederich, Simon

We discuss the proposal by Sebens and Carroll to derive the Born rule in Everettian quantum mechanics from a principle they call ‘ESP-QM.’ We argue that the proposal fails: ESP-QM is not, as Sebens and Carroll argue, a ‘less general version’ of an independently plausible principle ‘ESP’ and can only be motivated by the empirical success of quantum mechanics, including use of the Born rule. Therefore, ESP-QM cannot have the status of a meta-theoretical principle of reasoning and provides no viable basis for deriving the Born rule. ...

Adherents of a `rationality principle' approach to Everettian QM, such as Deutsch and Wallace or Sebens and Carroll, acknowledge that Everettian QM does not allow for the deduction of objective probabilities of measurement outcomes. Moreover, they feel discontent with simply introducing the Born rule as a primitive instrumentalist principle. The proposed way out is to open up the additional playing field of requirements of rational reasoning in the given context.
Got that? Many-worlds does not make any quantitative predictions. None.

It is not an alternative to Copenhagen, or to any scientific theory. There is nothing scientific about it. It is "not even wrong", to use the phrase Peter Woit popularized. It is just some meaningless fantasy.

The whole thing is so ridiculous that it is hard to take seriously anyone who believes in it. Yes, it causes me to doubt everything else Carroll says. Carroll is essentially saying: "QM appears to be a wonderful theory with many accurate predictions, but I don't like it so I want to replace it with a theory that does not make any predictions."

Dawid is a proponent of string theory, which does not make any predictions either, but the string theorists at least promise that they might get to some testable prediction in 50 years or more. The many-worlds people pretty much rule out the possibility of ever making any predictions.

Thursday, January 2, 2020

Smolin preaches nonlocality nonsense

I posted against those obsessed with quantum understanding, arguing that they are just resisting the accepted physics of 1930.

This is not a straw man, and here is another guy stuck in 19th century physics.

Physicist Lee Smolin explains his view of physics:
Then there's a small number, and I'm one of them, that take the problems in quantum mechanics as evidence that the theory is wrong, or at least incomplete. ...

There is a key idea that underlies my work in that area, and that's the problem of what's called nonlocality. This is a very important hint. Nonlocality is the phenomenon — also sometimes called entanglement — that if you have two quantum systems and they interact and then separate, they share properties, in that the choice of what property we measure on one of those particles, even if they're very far away from each other, affects what's measurable in the other particle. That's a statement of what's sometimes called Bell's theorem, and it's been put in a form where it can be tested experimentally. The experiments clearly show that the assumption that the two particles are independent because they're far away from each other is wrong. If you want a complete description of the results of experiments on these kinds of systems, and not a statistical description in terms of probabilities, which is all that quantum theory gives in these situations, you have to posit explicit interactions and communication between the two particles.

I believe that's right. That's what would be called a nonlocal theory. Traditionally, we call it a nonlocal hidden variable theory. There are a number of these — Louis de Broglie invented the first, called pilot-wave theory. It was laughed out of town by people in the late 1920s. There were theorems that showed it was impossible in the early thirties, and it was basically dropped by de Broglie and everybody else and then rediscovered by David Bohm. That's the first nonlocal hidden variable theory we have, and there are others.
No, this is just a misunderstanding of basic physics. Once separated, the two particles are independent. Nothing you do to one can possibly have any effect on the other.

Hidden variable theories were laughed out of town because they were throwbacks to outmoded theories that had been discarded as wrong. Bell's theorem and subsequent experiments showed that they were impossible, unless you adopt some mystical views. Sensible physicists concluded that the conventional wisdom of the 1920s was correct. Instead, Smolin takes the theorem as encouragement to become a mystic.