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The Quantum Labyrinth: How Richard Feynman and John Wheeler Revolutionized Time and Reality

door Paul Halpern

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"In Fall 1939, Richard Feynman, a brash and brilliant recent graduate of MIT, arrived in John Wheeler's Princeton office to report for duty as his teaching assistant. The prim and proper Wheeler timed their interaction with a watch placed on the table. Feynman caught on, and for the next meeting brought his own cheap watch, set it on the table next to Wheeler's, and also began timing the chat. The two had a hearty laugh and a lifelong friendship was born. At first glance, they would seem an unlikely pair. Feynman was rough on the exterior, spoke in a working class Queens accent, and loved playing bongo drums, picking up hitchhikers, and exploring out-of-the way places. Wheeler was a family man, spoke softly and politely, dressed in suits, and had the manners of a minister. Yet intellectually, their roles were reversed. Wheeler was a raging nonconformist, full of wild ideas about space, time, and the universe. Feynman was very cautious in his research, wanting to prove and confirm everything himself. Yet when Feynman saw merit in one of Wheeler's crazy ideas and found that it matched experimental data, their joint efforts paid off phenomenally"--… (meer)
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Almost as brilliant as Halpern's two subjects. ( )
  ben_r47 | Feb 22, 2024 |
Topic seemed narrow at first - the collaboration of 2 physicists - yet the topics they handle, the discussion they have and their own lives (especially Feynman of course), makes it a great experience.
I liked the pointers to different books and topics along the way. Made me read Asimov "The Last Question" for example.

Great explanations of complex concepts too, it's not just biographical. ( )
  jbrieu | Nov 6, 2020 |
In The Quantum Labyrinth: How Richard Feynman and John Wheeler Revolutionized Time and Reality, author Paul Halpern paints a mostly loving portrait of two leaders in the development and exploration of quantum physics. My scientist father loaned me the book, and it took several tries to get through it. I finally convinced myself that I could appreciate the story of two incredible thinkers without completely understanding the science.

Both men were passionate teachers and used teaching as a way to learn themselves. When John Wheeler, for example, realized that, in order to solve a particular problem, he would need to better understand general relativity:

The best way to learn a field was to teach it, Wheeler had found. he had acquired the habit of assembling meticulous lecture notes for each course, which could double as an excellent resource whenever he continued to research a subject. Often in his notebooks, he scattered speculation among his course notes. He might ask those questions of his students, consider them himself, or both. Learning begets teaching, which begets more learning, in a marvelous spiral of rising knowledge. (p. 173).

In fact, Halpern writes, because physics is "built from the ground up, based on fundamental principles that might be stated or interpreted in many ways...Even concepts typically addressed in the first weeks of an introductory physics course, such as force and inertia, are nuanced" (p. 22). According to Halpern, working together on Wheeler's classical mechanics course at Princeton led to conversations about Mach's principle of distant stars causing inertia and how it might still be relevant when we know the universe is expanding. These conversations spilled over into the classroom as they challenged their students to think hard about the concepts.

Feynman, of course, became known as the great explainer. ( )
  witchyrichy | Feb 20, 2019 |
“It’s worth a lot of miles to talk with you about anything and everything.”

John Wheeler referring to Richard P. Feynman, November 28, 1978 (Caltech Archives) in “The Quantum Labyrinth” by Paul Halpern

“His ideas are strange; I don’t believe them at all. But it is surprising how often we realize later that he was right.”

Richard P. Feynman referring to John A. Wheeler, in “Inside the Mind of John Wheeler”, 1986, in “The Quantum Labyrinth” by Paul Halpern

“To be normal or unconventional, that is the question. Is it better to be regular, predictable, and straightforward or bizarre, haphazard, and mercurial?”

in “The Quantum Labyrinth” by Paul Halpern

Do people in Quantum electrodynamics end their proofs with Q.E.D?

It is known for a long time that gamma ray photons of energy 1.02 MeV or twice the mass equivalent of an electron or positron produces an electron positron pair while striking a heavy nuclei (with high positive charge) like lead for example - the opposite process of electron-positron annihilation. The idea that the quantum vacuum teems with virtual electron-positron pair was demonstrated first through Lamb shift and later by others like Casimir effect. The QED and the Uncertainty Principle allows the possibility that some of the virtual particle can become real particles when sufficient energy for their mass equivalent is available or even through quantum tunneling when sufficient energy for equivalent mass is lacking. This hypothesis is also used to explain the origin of the galaxies (The Breeding Galaxies) as opposed to the Big Bang theory (please see my comment below).

In addition to laser technology for pair production (from virtual particles) described in this article; pair production from virtual states has been practically achieved by various other means including electron-nucleus “bremsstrahlung” in the field of a nucleus; pair production in collision of two ions in accelerators; pair production in constant electromagnetic field; pair production by circularly polarised laser beams; pair production in electron beam laser collisions etc. There’s an interesting paper on this.

Wheeler is probably the greatest physicist not to get a Nobel Prize. And Emmy Noether not only invented 'modern algebra' but in her eponymous theorem framed pretty much the whole of 'modern physics' up to now, and for the future (beyond the Standard Model). Yet till the very close of her life she wasn't even awarded a proper job, or paid for her work. I've often wondered if only a woman could have done what she - generally recognized as the greatest female mathematician in history - did: provide the overall framework in which all her male colleagues and successors, notably Einstein, eventually did their work (he wrote to Hilbert "You know that Frau Noether is continually advising me on my projects and that it really through her that I have become competent in the subject.")

But I'm rather mystified about the idea of 'converting energy into time'. This seems like a basic confusion about Emmy's 1931 Theorem, which shows, among everything else, that conservation of energy is equivalent to the time-invariance of physical 'laws': 'everything else being equal' a physical process will occur the same way 'at any point in time'. I think it's based on a false analogy with the way Noether's Theorem frames 'lower-level' symmetries that correspond to things like electromagnetism and the weak interaction within, say the deeper symmetry that frames the electroweak interaction, and so on. That measuring a system changes it is now widely accepted in quantum mechanics so yes - measuring the electron at the speed of light changes it. The comparison to an ammeter is difficult because then you're dealing with much larger systems which quickly get really hard to deal with in quantum theories. As for a scientific explanation as to why this should be - that's still in debate. Current understanding is fairly hazy - the best we can say at the moment is that this happens and is sort of 'just how the universe works'... It's not very satisfying admittedly. Superposition is a rather complicated subject. In essence, you can say that any system has a certain set of allowed states. For example we can consider an electron in a box - in this case we can consider the allowed states for the electron to be in to be to do with where it is in the box (i.e. in one corner, in the middle, 5cm to the right of the middle... there are an infinite number of possible states in this case). In a classical view the electron is always going to be in just one place - i.e. just one of these states. However, in the QM view the electron can be in a superposition of these. There isn't really a classical analogue for this which makes it very hard to explain but you can sort of see it as the electron being in several states (i.e. places) at once. If you try and measure exactly where the electron is then the superposition collapses and you'll find the electron to be exactly in one state (place). Here's where it gets interesting (and unfortunately more complicated). The position of the electron isn't the only property that it has. It also has a speed and another property that we call spin. Spin is a strange property connected to magnetism and similar effects but it's enough for this discussion to say that an electron can be either spin up or spin down.

Returning to the electron in the box we can now talk about it being in a particular position and having spin up or spin down - both of these pieces of information contribute to specifying its state. The electron can be in a superposition of both spin and position - trying to measure its spin collapses it into a definite spin state and trying to measure exactly where it is collapses it into a position state. I'd like to include the electron's speed into this too. A quick comment about this first - in physics we tend to use a quantity related to speed called momentum as it makes more sense in these circumstances. For speeds much less than the speed of light momentum is just mass x speed but at higher speeds its a little more complicated than that. Momentum also has a special relationship with position in QM. The formal way to say this is to say that they don't commute. What this means in practice is that you can't exactly specify the electron's position and its momentum.

Returning to the electron in a box once again, this means that while we can simultaneously talk about its state in terms of position and spin (or indeed momentum and spin) we can't do the same in terms of position, spin and momentum. It turns out that a position state is actually a superposition of many different momentum states and vice-versa. This then has a really interesting effect. Say we exactly measure the position of the particle. As before, this collapses it into a single position state but it also forces it into a new superposition of momentum states. If we imagine that the box is infinitely large then we find that this superposition actually gives the electron equal probabilities to have any momentum! This is connected to the uncertainty principle (which means that the uncertainty in a particle's position and its momentum are related - the less uncertainty in the position the more there is in the momentum).

Of course in the world as we experience it this doesn't seem to happen. The reason for this is that we never actually measure anything exactly. These effects only really become apparent when you move down to scales around the size of an atom and smaller.

Bottom-Line: Feynman had great advice for Sean Carroll, Leonard Susskind, Lisa Randall and all the other shmucks trying to promote the idea that string theory is the only way to proceed beyond the Standard Model of particle physics, even though no experimental evidence has been produced to support it. Without testable predictions, it's no longer science, it's philosophical speculation. Sean Carroll may have a Ph.D. from Harvard, but he's no Feynman, and he's no Dirac. He and the others are very smart people, but suffering from self-delusion. Unfortunately, most science journalists (and some Physicists as well) who write about String Theory for the general public only took an intro physics course in college. I'd recommend a visit to Peter Woit's "Not Even Wrong" blog on the internet (or read his book with the same title), so they can begin to see that string advocates are perhaps trying to sell us a bunch of snake oil, in order to advance their careers. A theory doesn't pass muster simply because its equations are beautiful. It has to be supported by data, and if our current technology won't allow us to reach the very high energies required to do a decisive experiment, then string theory is simply stuck in the mud. Feynman's all over the map with accomplishments in physics. I'm simply talking about the way they can both express themselves. The way they can talk about a topic very clearly. That's all. Science is sometimes not that easy to explain. I have trouble taking what I have in my head and breaking it down for others who are not too science trained. I admire the quality in Feynman as in Tyson (Tyson is great at science. Where he fails is that he worries about what inferior minds have to say. He has apologized for things he shouldn't, to people who are too petty to even matter) and Sagan to talk about science.

NB: Feynman had a 'turbocharged' mind! You can “feel” the fire within him to explore reality at every level and kick ignorance in its teeth! The age of the rock star scientist is over. Who are our rock star scientists? Richard Bloody Dawkins, and that's why nobody's got the old curiosity any more, they're turned off by tossers. John Archibald Wheeler on the other hand wrote a book along with Kenneth Ford called “Geons, Black Holes, and Quantum Foam”. One of the later sections in that book is titled "It from Bit" as he discusses the new idea of all matter being seen as information (Halpern writes about it briefly). ( )
1 stem antao | Sep 15, 2018 |
There are two natural divisions in quantum mechanics. The first focused in Europe, from Planck through Einstein to Heisenberg. The second was in the United States, with European refugees working around the likes of Richard Feynman and John Wheeler in the runup to the second world war. The Quantum Labyrinth is about this second era, from the late thirties onward. It is as much biography as science. Paul Halpern has pulled together the lives of numerous protagonists, giving them humanity and human foibles amidst the admittedly difficult and bizarre world of quantum mechanics. Feynman himself famously declared that no one understands quantum mechanics. And he was in the eye of the storm.

John Wheeler and Richard Feynman form the spine of the story. They encounter and work with literally everyone who mattered in the discipline. That they met is remarkable. Feymnan transferred to Princeton specifically to become a teaching assistant to Eugene Wigner. Instead, he was assigned to Wheeler. Wheeler turned out to be just seven years older than Feynman, and had a very similar sense of himself and science. The two of them hit it off immediately, and spent endless hours laughing at everything and nothing together. Eventually Wheeler became Feynman’s Phd advisor, and they worked together basically the rest of their lives. Their discoveries fill book shelves.

Nothing in quantum mechanics was too wild for Wheeler. He dreamed in Technicolor. Feynman, no slouch in the imagination department either, took Wheeler’s ideas and provided mathematical proof and justification (where possible), not a year later, but in hours. Not to put too fine a point on it, Feynman obtained his doctorate in three years. Together they assaulted the boundaries and pushed them off in new directions.

The book is at its best when Halpern tells stories showing the physicists’ human side. When Feynman gave his first public lecture at Princeton, “a collection of monster minds” attended. Names like Von Neumann, Wigner, Pauli and Einstein. Before it began, Einstein interrupted Feynman at the blackboard and asked where the tea was. Feynman said he was relieved to be able to answer at least one of Einstein’s questions.

Wheeler invented the wormhole, named Feynman’s method sum over histories, and promoted the term black hole in popular science. When the universe was not enough, he tackled information – the world of bits instead of subatomic particles. It was a Wheeler brainstorm that led to the theory there was just one electron, racing around the universe showing itself.

What weakness there is in The Quantum Labyrinth is in Halpern’s discussions of quantum mechanics. It’s his profession, and he doesn’t make it easy for readers. What usually happens is Wheeler or Feynman has made some huge discovery, and Halpern asks us to step back to understand the mechanics of it., right down to the fundamentals. There is no math, but it is still dense.

It turns out physicists are real people, with quirks as well as quarks. Bohr mumbled incoherently. Dirac was painfully introverted. Feynman was always up for adventure. He played bongos into the wee hours (it was cited in his divorce), acted in plays at Caltech and was the most entertaining lecturer anyone had ever experienced: “a magician of the highest caliber.”

The story has not ended, of course. There continue to be more questions than answers, and it gets worse with every discovery and every new theory. The labyrinth is of their own making. That no one can find the way out is a clear indication that much of what is claimed is simply wrong. The value of The Quantum Labyrinth is the real, human side of this voyage of discovery.

David Wineberg ( )
  DavidWineberg | Aug 18, 2018 |
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"In Fall 1939, Richard Feynman, a brash and brilliant recent graduate of MIT, arrived in John Wheeler's Princeton office to report for duty as his teaching assistant. The prim and proper Wheeler timed their interaction with a watch placed on the table. Feynman caught on, and for the next meeting brought his own cheap watch, set it on the table next to Wheeler's, and also began timing the chat. The two had a hearty laugh and a lifelong friendship was born. At first glance, they would seem an unlikely pair. Feynman was rough on the exterior, spoke in a working class Queens accent, and loved playing bongo drums, picking up hitchhikers, and exploring out-of-the way places. Wheeler was a family man, spoke softly and politely, dressed in suits, and had the manners of a minister. Yet intellectually, their roles were reversed. Wheeler was a raging nonconformist, full of wild ideas about space, time, and the universe. Feynman was very cautious in his research, wanting to prove and confirm everything himself. Yet when Feynman saw merit in one of Wheeler's crazy ideas and found that it matched experimental data, their joint efforts paid off phenomenally"--

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