31 Comments

"Mach is one of those guys who was incredibly famous and impressive in his day, but is now totally forgotten.² His jobs included physicist, philosopher, psychologist and social reformer, and he made a splash at all of them. He was also a radical empiricist who believed that the only things worth talking about were the things we can see, touch, or otherwise measure."

In 2018, I met Rainer "Rai" Weiss. It was a few months after he got the Nobel prize for LIGO--at least being the face attached to it. The husband of the librarian at my old high school in New Orleans had worked with Rai in the past and when he saw the accolade, he invited him to speak at the graduation. I attended it to hear Rai and I threw a dinner for him afterward, so I got to spend quality time asking him questions and generally shooting the bull with him. Great guy.

One of his main points was that Einstein had predicted the existence of gravitational waves, but he also predicted that, because they are so almost incomprehensibly small, they'd never be detected. LIGO proved the first to be correct--they're real, but the second to be wrong--LIGO found them. In fact, they pick up about fair number of them. Tens to hundreds of solar masses get turned into GW energy when black holes collide with one another and when black holes collide with neutron stars. That's an enormous amount of energy. The effect on the LIGO is a shrink/expansion of the kilometer-long interferometer arms of ~ 1/2000th the diameter of a proton. We're talking one part in about 10^24. That's a 1 followed by 24 zeroes. Not a surprise the Albert predicted it would never be measurable, but he hadn't anticipated engineering 100 years after the prediction.

Back at the dinner table...I'm sitting across from Rai, and next to the principal's wife, who asks animatedly about things like alternate universes. Rai pleasantly says that he thinks that physicists ought not to delve into unmeasurable fantasy things, like alternate universes. I ask him if he remembers pointing out that Einstein had predicted that GWs wouldn't be measurable either....

It was a light moment.

Expand full comment

An entertaining/enlightening read, as always! I have a question though:

> You might object, “if two theories are indistinguishable by observation and experiment, then they are equally valid and it doesn’t matter which one we pick.” But come on, while some philosophers might say that, nobody actually believes it.

… does nobody believe this? The strong form even seems obvious, if you have two theories which agree on every single prediction they make, even if they’re superficially different in some way, isn’t it the most natural conclusion that these are in fact the same theory, seen from different perspectives? It’s like a surjective mapping defining an equivalence clas, A->C, B->C => A~B.

Expand full comment

The theory that there is a unicorn behind you at all times but that the universe itself conspires to make it so that you personally cannot perceive it directly or indirectly by any means (your friends are compelled by strange force to lie to you about it, cameras do not perceive it, various outlandish nonsense) is indistinguishable by any observation or experiment you could possibly do. But it's still somehow different than not believing in it.

Expand full comment

The above is not a good example because it is not a theory, when Mr Psmith speaks of a theory, he means it in a scientific context. A scientific theory is a “well-substantiated explanation of an aspect of the natural world that can incorporate laws, hypotheses and facts.” He is specifically talking about equating competing explanations for some observable phenomenon (gravity, electromagnetism, rain, etc). You can add unicorns if you wish, but it makes no difference to the theory to add or remove the unicorn (though personally I would remove it, as the Lagrangian for an invisible unicorn is probably difficult to write down).

A better example that makes your point would be something like the uninformed experimentalist’s (that’s me!) favorite punching bag, interpretations of quantum mechanics - Many Worlds? Copenhagen? Pilot Wave? Pick your poison. But so long as these theories are indistinguishable by experiment, even in principle, they’re philosophy, not physics.

Expand full comment

Lots of people do believe it; I believe it.

It could be that Mr. Psmith is meaning it in a slightly more nuanced way than we're reading it, though. I hope he'll clarify in an answer to my own question!

Expand full comment
author

It's funny, you guys think I'm being unfair in one direction, but I got an email accusing me of being unfair in the other! Rather than "yes lots of people believe this" it was "you're strawmanning, nobody even claims to believe that." I will point that emailer at this comment thread.

More seriously, I will try to write something longer about this in the future!

Expand full comment

Scott Alexander had a funny comment once about how he wishes his critics would get together and decide which way he was being unfair, instead of coming to him first.

Expand full comment

There's far more to recommend a theory than it's external prediction record. Internal simplicity, ready further testability, relationship to other theories and so on.

Expand full comment

Sheesh, I know what that's like!

I wouldn't say you're being unfair, I just don't agree (or don't really understand). Take your time, we're all reading.

Expand full comment

I don't really agree with the thrust of your remarks here.

> In a few short sentences Einstein completely repudiates the empiricist spirit which has ostensibly guided scientific inquiry since Francis Bacon. He doesn’t care what the data says.

My sense is that nonphysicists love Einstein, in part, because they don't realize he's like this. Einstein's lack of humility in the face of nature's disconfirmations of his beliefs is even more stark when he insists that "God doesn't play dice." Neils Bohr was the better scientist, and his reply, "Don't tell God what to do," shows why: he could submit to reality and accept it on its own terms.

> When it falls, its mass doesn’t matter at all. I don’t think most teachers do a good enough job drawing our attention to how extremely weird this is — but it’s weird enough that the Aristotelians got it wrong for centuries!

I've spent a lot of time pointing out how bad Aristotelian physics is, but this really doesn't strike me as being particularly interesting. Newtonian physics says it's the mass itself that causes the pull, so how could gravity be a 1/m phenomenon? Sure, everything else spreads force over mass, and ends up with a ~ 1/m because "everything else" is some force that exists on its own, or for some other reason. But if more mass means more force, of course a is no longer proportional to 1/m. It just seems inevitable.

> if two theories are indistinguishable by observation and experiment, then they are equally valid and it doesn’t matter which one we pick.” But come on, while some philosophers might say that, nobody actually believes it.

Mr. Psmith, I wonder why *you* don't seem to believe this. It isn't very hard.

Is it wrong to call Dorian a major mode with flat 3rd and 7th note, when we could more easily call it a minor mode with a sharp 6th note? Is it wrong to say love draws spouses together, when we could just as easily say they love each other because they're drawn together? Why do you think it matters?

Expand full comment

Yeah, even the first quote, is more about what he liked about the idea,

"because they avoid the inertial system... It is really quite strange that"

Just read Einstein, he's great. (Even in translation)

Expand full comment

How did you typeset the math equation? Did you use MathJax? How do you do that in Substack?

Expand full comment
author

Substack allows you to add a LaTeX block. I am firmly of the belief that numbers belong only in the corners of pages but I assume that’s what John did!

https://support.substack.com/hc/en-us/articles/12291042958996-How-do-I-add-equations-to-my-Substack-post

Expand full comment

I'm not sure when, but Einstein once called himself a Spinozist, which implies rejection of miracles, which implies skepticism on observations untethered to natural frameworks.

Expand full comment

Regarding Einstein's belief in theory over experiment, I'm not sure he was as sanguine as the quote portrays. He once famously said that if the general theory of relativity were to be proven experimentally, Germans would proudly refer to him as a German, and the French would call him a citizen of the world. If Eddington's experiment hadn't shown the predicted precession of Mercury's orbit, the French would have called him a German and Germans would call him a Jew.

This doesn't mean that he wouldn't have still believed the theory, but not confirming a highly specific prediction would have certainly called it into question. As it turns out, I'm unaware of any evidence that contradicts the theory. In fact, I only know of one major problem with Einstein's comments....

https://xkcd.com/1206/

;-)

Expand full comment

Einstein's change described here is a perfect illustration of the divided line Socrates describes in the Republic. Moving from the seen to the intelligible.

Expand full comment

My initial thought after reading this is the stock market, and the use of quantitative tools, to optimize trading to make money. There is so much price information over the decades that presumably that would be the perfect place to mine for a grand unification theory of the markets if you will. I wonder if Einstein were around today whether he would have been a hedge fund manager.

Expand full comment

'On Scotland and the Scotch Intellect' by Henry Thomas Buckle is a reprint of a part of Buckle's 'History of Civilization in England'. Buckle viewed the Scotch Intellect as essentially flawed by inductive logic. Stupid Scotch, incapable of deductive logic, the only true logic. A good return of serve to all that Scottish Enlightenment stuff. But the Scottish Enlightenment was real, and got more accomplished than the life of the mind in England of its time, and Conan Doyle did some good riffs on deductive logic in Sherlock Holmes.

This was in the air during Einstein's 1905 Anno Mirabilis.

Expand full comment

That condition in the last sentence is bearing a very heavy load. To a first approximation, no-one is as smart as Einstein was.

Not as reassuring to quacks and eccentrics as they might think.

Expand full comment

I loved this. Thanks so much. Subscribed.

Expand full comment

Re: Footnote 8 and similar themes throughout the review, I suppose the obvious question is: How do we distinguish between people who are smugly overconfident despite the evidence and correct (because they're geniuses), and people who are smugly overconfident despite the evidence and wrong (because they're just arrogant and pigheaded)? All of us have met the latter, and in fact the latter is a defining trait of many people aggressively adhering to certain scientific and social theories that are causing us great harm (insert South Africa book review link here).

But maybe that's just the thing: We *can't* easily or consistently distinguish the two, but we just have to bit the bullet and acknowledge this sort of thing existing is a good thing. The obvious comparison is to the world of entrepreneurship: Most businesses fail and objectively it's often not a +EV play to do startups over safer paths, but some people just decide "screw the odds" and we benefit from it long-term. A certain behavioral variance is desirable for the overall system. MOST people who are smugly overconfident in the face of measured evidence are just being pigheaded or arrogant...but we still need those traits for the occasional person who is that arrogant because they're right and need the guts to stay the course.

Expand full comment
author

My point (and Feyerabend's) is less prescriptive ("it is good that scientists ignore the evidence") and more descriptive ("many scientists act this way, including some very famous and successful ones").

I think if you wanted you could make a case that it *is* good at a whole-ecosystem level. Kuhn and Feyerabend both point out that even a correct theory is often incorrect or unable to explain all the evidence in its initial form. So if everybody was rigorously culling theories that didn't explain the best available evidence, new theories would have trouble getting their footing, and science would never progress. Scientists ignoring the evidence or sweeping it under the rug is harmful in each individual case, but overall positive because it means that new theories which are onto something have time to build their defenses and win adherents.

Another, less outrageous-sounding way to put this is that perfectly-efficient competition can make it hard to pull off big and risky moves in any domain.

Expand full comment

Einstein wasn't correct despite the evidence when it came to quantum mechanics. He completely s*** the bed and insisted the moon is there when he's not looking at it. His fans remember him as a great physicist, but I remember him as a kind of halfway scientist who pioneered relativism while struggling with the obvious in quantum because it violated his hubristic belief that he really, really knew what reality was all about, really.

Expand full comment

David Deutch’s criticisms of induction in his book “The Fabric of Reality” also seem on point here.

And you are exactly right about the execrable NdGT.

Expand full comment

do you really mind him so much? He’s never really bothered me. It’s not like he says anything that’s grossly objectionable from a physicist’s point of view, it’s more like how high school physics is an approximated, abbreviated form of the higher level concepts.

Expand full comment

As a person who only ever reached high school physics (and doesn't remember much of that) I would be interested in learning some ways that ndGT is wrong -- whether grossly objectionably so or not. I have some experience with his work, but I don't know enough about it to know why some people think he's overrated, etc.

Expand full comment
author

My dislike of him is less about what he says on particular scientific topics, and more about the IMO oversimplified way he portrays science *as a process*.

Expand full comment

Well, I mean he’s not really wrong. It’s more just compressing complex topics into sound bites is inherently a lossy compression, and I suspect no one likes their profession reduced to sound bites. He isn’t wrong though.

Expand full comment

That makes sense. Thanks!

Expand full comment
deletedMay 29
Comment deleted
Expand full comment

I think that was a joke? They both look similar.

Expand full comment
author

Yes, it was a joke! Sorry if that wasn't obvious.

Expand full comment