A correspondent points out to me that the latest issue of American Scientist has a wonderful review of Roger Penrose’s new book The Road to Reality by computer scientist, author, artist, etc. Jaron Lanier, much better than my own effort along these lines. Despite not being a theoretical physicist, Lanier does a great job of recognizing and explaining what is great about Penrose’s book. He also is dead-on about string theory (“mob mentality”, “pompous triumphalism”).

The same issue of American Scientist also has a very good review by Lee Smolin of Gravity’s Shadow: The Search For Gravitational Waves by Harry Collins. It also contains a nowhere near as good review by yours truly of Sneaking a Look at God’s Cards, a book about interpretational issues in quantum mechanics by Giancarlo Ghirardi.

Penrose’s book reminds me of Maxwell’s Treatise on Electricity and Magnetism, being a mixture of ingenious physical ideas and really awful mathematical methods. Quaternions feature prominently in both Penrose and Maxwell, without any real justification.

Whenever I see the picture of Penrose’s twistor, I automatically wonder what the lines are, electric field, magnetic field, or Poynting vector of energy transfer? The same happens with field lines in electromagnetism. If you have a Poynting vector going around in a simple circle, you get a dipole magnetic field which looks similar to Penrose’s twistor, while the electric field lines spread out radially.

I didn’t think I had the background to fathom the book. Now I’ll have to take a look at it. So you guys think a mere math B.S. can digest the thing?

My own impression of the book was that to fully understand everything Penrose is doing, you probably need a graduate level background in math and physics. But large parts of the book are quite accessible, especially if you have some basic university level mathematics background, so if you’re willing to skip some things that seem too difficult, you should find much of the book well worth time spent with it.

Maxwell was just thinking ahead to the weak force and Penrose is just thinking ahead to conformal gravity. I attended a presentation by Penrose once, it was great but as usual I felt like the AFLAC duck wanting to yell out “TONY SMITH”. Smith upgrades quaternions to octonions and gravity to conformal gravity.

Hi Peter. I’ve been a lurker here for a while and am looking forward to your book. Good luck! In your review of Ghirardi’s book, you write:

“Most physicists generally believe that quantum mechanics, in its relativistic version as a theory of quantum fields, is a complete, consistent and highly successful conceptual framework. They assume that there must be some well-defined way of describing the entirety of a physical system, experimental apparatus and human observer, appropriately dealing with the confusing interpretational issues. As a result, the study of the sorts of questions examined in this book has often been considered somewhat of a backwater.”

I can understand that belief as contributing to the view of foundational research as a backwater, but I would suggest something more sociologically profound is going on. The belief amounts to the non sequitur “we are sure there is an explanation, but we don’t know exactly what it is, so we look askance at anyone who tries to explicitly figure it out.” Not exactly a normal, scientific attitude. The high energy frontier is perhaps not the only unstable orthodoxy in physics.

Given the above quote, I’m curious if you think that the foundational issues are somehow attenuated in (relativistic) field theory. I’d say they just get harder. When field theory is introduced into the discussion, it’s usually intended to downplay the significance of Bell Inequaltiy violation, since it’s not clear how to formulate Bell’s argument in terms of in/out state scattering. But this is just an inadequacy of the standard field theory measurement formalism, not a solution to the problem.

Regards,

Eric

When I saw how big the book is, I thought, and still think, it will take me some time to read it (also, I am busy with graduate work, so time for leisure is quite restrained these days). So I bought the book as a present for a good friend. Hopefully, he’ll tell me a nice story at some point (he has not given any feedback so far). I did majors in pure maths, applied maths and physics, so I think the necessary background is there. ; )

From Down Under

Hi Eric,

I’m really not an expert on interpretational issues, so from one point of view wasn’t the best person to review that book. But I’m interested in the topic, and think my prejudices about it are pretty common ones among theoretical physicists, so part of what I wanted to do was to explain what those prejudices are.

One thing that this kind of QM and string theory seem to me to have in common is being largely insulated from experiment, and full of people who have an ideological ax to grind. What I’ve seen of the QM literature is often as depressing as the string theory literature. Without the discipline of experiment, theoretical physics seems to easily degenerate into nonsensical blather. I’d like to believe that QM will get more interesting as people figure out how to manipulate more interesting quantum mechanical systems. Maybe this is overly optimistic, we’ll see.

I have no idea whether the resolution of interpretational problems requires thinking about quantum field theory. But quantum field theory is far and away the best fundamental theory we have. It seems to me that, absent any interesting experimental data to chew on, theorists of all kinds should be spending a lot more time thinking deeply about QFT. My own approach to this is mathematical, I suspect there are mathematically much deeper ways of thinking about QFT than the ones we know about. If and when we figure these out, maybe they’ll shed some light on the interpretational issues, maybe not.

Here’s a paragraph from Lanier’s review of Penrose’s book, Peter:

Perhaps you feel that you’re obligated to say nice things about Lanier’s review since your own book review was published in the same issue of the magazine and you might like to publish there again, but, really, if your BS detector doesn’t peg after reading that paragraph, I’m going to have to reconsider my estimate of the seriousness of your devotion to debunking. Comparing the Feynman lectures to Gamow’s little trade book? And then suggesting that Penrose’s book (which I’ve read, BTW) is superior to both?

If Lanier even understood most of the words in Penrose’s book, I’d be quite surprised.

Penrose undertakes a difficult task and I was surprised how enlightening his treatment of electromagnetic theory is in tensor notation, chapter 19. If you look at Maxwell’s theory in Feynman’s lectures, you find that Feynman avoids tensors altogether, sticking to vector calculus (divergence and curl, which do what their labels say). Where Feynman tries to explain GR without tensors, he comes up with the ingenious physical contraction of space in the radial direction only around a mass, which indeed is precisely the special feature of the contraction term that Einstein introduced. However, the Feynman lectures by keeping to simple mathematics, are limited. Gamow’s ‘One Two Three … Infinity’ falsely debunks the idea that the Lorentz contraction can be considered a physical pressure effect of moving against the spacetime fabric. Gamow tries to obfuscate by claiming different materials would contract differently, when in fact the compression forces involves are always electrical and the contraction would be similar. So for all their skills in physics, I don’t see how anybody can learn sufficient physics from the popular books of Gamow and Feynman. The Penrose book excels at sticking to mathematics and physical facts, without the self-opinionated interpretational baggage…

Nigel, my point was that Lanier sets up a sort of parity between the Feynman Lectures and Gamow’s book, which is silly (and leads me to suspect that he’s not spent a lot of time reading either book). Then, lumping these two very unlike texts together, he asserts that Penrose’s book is superior to both.

As a loose analogy, consider equating the acting skills of Sir Laurence Olivier and Jon Lovitz, and then going on to say that Russell Crowe is better than both. The initial equation calls one’s judgment into question, even though it might well be the case that at least in some respects Russell Crowe

isa better actor than both (although the standard Crowe must beat is much higher in the case of Olivier than in the case of Lovitz).With apologies to the Master Thespian, of course…

Sorry, but I was really legitimately very impressed by Lanier’s review, and wasn’t saying nice things about it because the folks at American Scientist just paid me a fee in the high zero figures. His language may be a bit over the top, but Penrose’s book is something very unusual, so this level of enthusiasm seems to me not inappropriate. I don’t remember Gamow’s book, I think I probably read it more than thirty years ago. The comparison to Feynman is appropriate, that’s one of the few other books of at all similar scale and ambition. Penrose is much more of a mathematical physicist, so his book is much more mathematical. If your taste runs more to mathematical than physical arguments, Penrose’s is definitely a better book than Feynman’s. For purely physical arguments though, you’re better off with Feynman.

I don’t know Lanier personally, but do know people who do, who had told me he’s a very impressive character, with knowledge of a wide range of subjects. His review certainly demonstrated this. He correctly pointed out many of the best and most striking things about the book, made a wonderful analogy to the book that made Camille Paglia famous, and did a fantastic job of situating Penrose, his point of view and what he was trying to accomplish with the book in the context of contemporary theoretical physics.

Lanier’s comments about string theory certainly did endear him to me, so if you want to accuse me of being seduced into feeling obligated to say something nice about the review, it would be those that did it, not the American Scientist connection. But I can assure you that I thought the review was great and at no time felt I had to say nice things about it for any other reason.

Okay, I’ll let you slide on this one. Heck, I wouldn’t have sold out for $0 either. They would’ve had to pay me at least $&epsilon for some ε>0.

And for the record, I, too, read Gamow’s book decades ago and have little recollection of its details. But I’m not the one who mentioned it in a published review, so I’m cutting myself (and you) some slack on that score.

Regards…

Lost a semicolon after that first epsilon, I see. Dang.

Nigel, where is Feynman limited by not having tensors? He can’t unify GR and electroweak/color I suppose but tensors can’t do that either. You need something like SU(5) GUT which from a spacetime point of view could be like adding Kaluza-Klein-like dimensons.

Some interesting history from Tony Smith’s site:

http://www.valdostamuseum.org/hamsmith/HeisHist.html

How many times does this book mention Godel’s theorem?

I was a grad student at U. Cal. Irvine back when Joe Weber taught there (he was also teaching at U. Maryland, if I recall). Most of the small amount I know about gravitation I learned in his class, which he taught out of his book. He died quite recently.

Carl

The book has a couple pages about Godel’s theorem.

John: Feynman pulls his simple formula for contraction of space around a mass out of thin air, like magician pulling a rabbit from a hat. Penrose goes into mathematical physics a bit deeper. In your link Tony Smith deals with Feynman’s lectures on gravitation (1995 publication), not the lectures on physics.

Today, I received a copy of Sir Penrose’s The Road to Reality. After a brief glimpse, I think it is the graduate’s Feynmann’s Lectures on physics!

It tells us with caution what we did know, what we are now doing and in what directions shall we go?

But here is a question in Page 659: why the commutation(anticommutation) relations involve the imaginary number i?

Peter,

I found your review extremely frustrating because it didn’t answer the single most important thing anyone reading a review wants to know: should I devote some of my precious and very limited time to reading this book. The book, apparently, covers material we have all seen many times and, as least as far as your review goes, says absolutely nothing that wasn’t said thirty years ago.

Bohr, EPR, entanglement, Bell, Aspect, it’s all very mysterious, blah blah.

It sounds like the only thing they have to offer is the sort of stupid ad hoc modifications people were making in the 50’s to non-relativistic QM. I honestly don’t know why people waste their time with this crap — it’s so clearly not going to fit into the larger structure. It’s like approaching rotation as something algebraic, and dicking around with the algebra, rather than viewing it as something geometric and making modifications that match that geometric view.

So the answer to my question would appear to “don’t waste your time, unless you’ve never, in your life, met this material before”. Is there a single thing they say that is not either a waste of time, or that would come as news to an intelligent 2nd yr grad student?

Is this a fair conclusion, and it was politeness and the conventions of the review format that prevented you from saying so outright?

Hi Maynard,

I suppose I should have made this clear in the review, but the Ghirardi book is aimed at people who don’t know much about interpretational issues in quantum mechanics. If you’ve thought about this stuff, read about it elsewhere, and have a graduate-level background in QM, the book isn’t aimed at you. It has a bit more about Ghirardi et. al.’s own approach than you’ll find in other books, but not that much. If you have some background and want to know about what they have done, you should read their papers.

I thought the best thing about the book was the way it wasn’t either too gee-whiz, or pushing a specific viewpoint. Some introductory books like this act as if QM is some complete mystery, Ghirardi doesn’t. He also doesn’t push his own research strongly, acknowledging that it has problems. It’s basically an even-handed introduction to the subject, aimed at the non-expert.

speaking of roger penrose, what do his peers think of his suggestion that gravity is what divides the quantum realm to the classical realm?