What Are You Reading?

Spooky Action at a Distance was an enlightening exploration into the history of non-locality in physics although there are several aspects to it and in many places in the text I was unsure exactly how the phenomenon being explained qualified as non-local. The premise of the book is that space, and likely time as well, are emergent properties of whatever is going on in a level below quantum mechanics and general relativity, but it couldn't in the end come up with more than a quick sketch of what a physics without space or time would look like. Still, I'm glad I read the book to see where the current frontier of physics is at.

I posted this last month in the Physics! group but this group is also appropriate and also relatively active.

I finished QED : the strange theory of light and matter and I think I understand the ideas a little better now, although I'd like to read some other non-technical books on quantum physics to get other perspectives. Also the book was written in 1985 and I know there have been more developments since then. I liked that he explained it in a way that made it clear exactly what is being calculated and why but not actually how to do the calculations.

Fascinating stuff. So what did the folks in the Physics Group have to say?

I'm currently dipping into Q is for Quantum at the moment because I've been introduced to the drug that is the 'QuizUp' app. It so happens that the phrase 'spooky action at a distance' occurs in a couple of questions that crop up regularly on the 'Quantum Physics' topic.

The Physics! group seems to be defunct.

>2 jjwilson61: I don't think there's been a whole lot of change in QED since Feynman wrote that book. It's a pretty complete theory and very successful at describing the universe. Once you add the other forces into the mix, though, the picture has indeed been changing. String theory and its successors haven't been supported by experiments at LHC and the field's in a bit of a turmoil about it.

I bought a slew of books on the physics of the last 60 years or so recently, having decided to finally move beyond my fetish for the glorious first decades of the 20th century. Haven't gotten to them yet, but I'll push QED higher up on the To Read pile.

>6 drneutron: He did say that QED explains all of nature except gravity and nuclear forces. I believe, but I'm not sure, that the nuclear forces had been unified so that the only remaining force without a quantum explanation was gravity.

He also mentioned a W particle that was involved in one quark changing into another causing proton decay and mentioned that it was too massive to be seen using the then current particle accelerators, has that one been detected? He also mentioned 5 quarks but Wikipedia tells me that there are 6.

>8 jjwilson61: Well, since there are 4 forces and QED is only about one of them, his claim of explaining all of nature except... seems a bit overstated. :) But it is an extremely successful theory for explaining electromagnetic phenomena.

The current Standard Model unifies electromagnetic theory as described by QED with nuclear forces described by quantum chromodynamics (QCD) that give how quarks interact through the strong and weak nuclear forces. The W particle he talks about is an "intermediate vector boson" and it was observed in 1983 in experiments at CERN. At the time of his writing, there were only 5 quarks known, but 6 had been proposed. Since then, the top quark has been observed, first at Fermilab in experiments in 1995. And just recently, the discovery of the Higgs boson adds further confirmation of the Standard Model.

Gravity's still not understood at the scale of quantum interactions, and many physicists think there may be an encompassing theory to unify it with the other three forces and to answer questions like why are there only 4 forces? And why are there only 6 quarks? And why do the quarks have the masses they do? String theory and its extensions are one way to try to find an overarching theory, but the recent results from the LHC at CERN don't support predictions made by string theory and the theory is vulnerable to criticism of its lack of predictive ability. Loop quantum gravity is another such effort to unify gravity with the other forces. It's an interesting time to be a physicist!

I read Feynman's QED back in 2005. According to my book log I liked it well enough, but I don't remember much about it anymore. A somewhat similar book that impressed me more in 2006 was The Quantum Quark by Andrew Watson, which focuses on the theory of QCD that drneutron mentioned in the previous comment. Another book in the vein of explaining what we know rather than speculating about what we don't is The Theory of Almost Everything by Robert Oerter, which covers the whole standard model of particle physics. That was another one I liked well enough when I read it in 2008. In 2013 I suggested The Infinity Puzzle by Frank Close for a book club I was in at the time; it was not well liked. I have heard good things about The Particle at the End of the Universe by Sean Carroll, which I have not yet read myself.

To clarify drneutron's previous comment, QCD only concerns the strong nuclear force. The corresponding theory for the weak nuclear force is unified with electromagnetism in an 'electroweak' theory that is 'hidden' by a so-called 'Higgs sector'. (Sorry for all the scare quotes, but they seem preferable to trying to explain all of those concepts in this comment.) While the standard model encompasses QCD, the electroweak theory and the simplest conceivable Higgs sector, the first is not (yet) unified with the rest.

Conjectural attempts to unify QCD with the electroweak+Higgs sector are called grand unified theories, and might be a step towards a fully unified quantum 'theory of everything' that also includes gravity. String theory as a potential theory of everything was mentioned by some previous comments. Loop quantum gravity was also mentioned; while I know relatively little about loop quantum gravity, my understanding is that work in this area generally considers gravity in isolation and doesn't (yet) attempt to unify gravity with the other forces. In this context neither string theory nor loop quantum gravity make any meaningful predictions that would be testable by ongoing or planned experiments. One might hope that such predictions might be produced if we were able to improve our understanding of these approaches, but in the absence of both enormous conceptual breakthroughs and extreme luck, results from the LHC just aren't directly relevant to them.

Lost In Math: how beauty leads physics astray ((2018) (2020) New York, Basic Books)

If you never got around to reading this, start with the newer expanded edition: The Design of Everyday Things

Recently finished reading Carl Sagan's The Demon-Haunted World, which I think still makes strong arguments despite its aged examples. It led me to find the latest "Cosmos" series on Netflix which is really well done, as demonstrated by my kids' perking up their ears as I watched it. I'm impressed by how it skips about through multiple fields of science without transition, keeping the sense of wonder going.

Cecrow, Sagan is an amazing writer. I recently bought one of the last books he wrote (w/ colleagues), titled The Cold And The Dark. Haven't read it yet, but soon ... it became famous as the title that first explained to Earth's general readers about the global problem of nuclear winter that follows the use of nuclear weapons.

A new discussion on theories about time:

https://www.quantamagazine.org/what-is-the-nature-of-time-20240229/

I just finished A City on Mars: Can we settle space, should we settle space, and have we really thought this through? By Kelly Wienersmith and Zach Wienersmith

>16 Treebeard_404: ----> if you did not yet see:

https://www.popularmechanics.com/science/environment/a60401230/climate-change-tr...

>17 MaureenRoy: Thanks for the heads-up, Maureen.

I'm a few chapters into In the Name of Plants by Anna Pavord. It's a brilliant idea: choose a set of plant genera and then, in addition to describing plants in each genus, tell the story of the people for whom the genera were named.