Dreams of a final theory

What Hacker News says

1. prvcJul 2021
   I read "Dreams of a Final Theory" as a child, and have been contemplating some of the philosophical questions posed therein ever since. RIP.
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2. oefrhaJul 2021
   Dreams of a Final Theory was one of the most influential texts that motivated me into theoretical high energy physics. Sad.
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3. ssivarkJul 2021
   I’ll share what to me was one of the most impressive aspects of Weinberg’s work. I’ve seen him described as a battle tank — not the fastest to get moving, but basically unstoppable once he does.

   As I was digging into the literature during my research, I noticed an interesting pattern to his work over the decades. There would erupt a “hot” area in applying quantum field theory, and have lots of back and forth and papers making claims, correcting each other, and being corrected. And then a few months/years later would come a Weinberg paper, handling the matter so systematically & thoroughly that there likely won’t be any more low-hanging fruit in the area!

   The whole thing was really impressive given that he worked largely by himself (most of his papers are single-author), and had among the highest average citation count I’ve seen for a theoretical physicist. There is a reason his quantum field theory textbook series is highly respected — he wrought the field piece by piece with his own hands.

   Finally, he was an extremely articulate writer, and I have a huge soft spot for his “Dreams of a final theory” — especially his comments on the relationship between theory & experiment, and the scientific method more generally. I really wish more people read that and got influenced by its depth and nuance.

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4. ssivarkApr 2021
   That’s a good (and profound) question, not deserving of downvotes.

   It turns out that the simplified paradigmatic “scientific method” is a very bad caricature of what actually happens on the cutting edge when we’re pushing the boundaries of what we understand (not just theory, but also experimental design). Even on the theoretical front, the principles might be well-understood, but making predictions requires accurately modeling all the aspects that contribute to the actual experimental measurement (and not just the simple principled part). In that sense, the border between theory and experiment is very fuzzy, and the two inevitably end-up influencing each other, and it is fundamentally unavoidable.

   Unfortunately, it would require more effort on my part to articulate this, and all I can spare right now is a drive-by comment. Steven Weinberg has some very insightful thoughts on the topic, both generally and specifically in the context of particle physics, in his book “Dreams of a final theory” (chapter 5).

   If you don’t have access to the book, in a pinch, you could peruse some slides that I made for a discussion: https://speakerdeck.com/sivark/walking-through-weinbergs-dre...

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5. earthicusJul 2019
   The view that Dirac is putting forth, that the fundamental equations need to be simple, is certainly not the modern one endorsed by theorists today. Since the 70s or 80s, the point of view that has come to dominate is that our most accurate theories (quantum field theories) are what are known as "effective field theories", where the adjective 'effective' refers to the idea that they are only only low-energy approximations to some other more complete theory. In this point of view the complete theory would have more complicated, even non-renormalizable terms that violate conservation laws, but these additional terms are suppressed by powers of something like the plank scale and so are virtually undetectable at low energies. Thus the low energy approximations (the effective field theories) have the simple, renormalizable form that we know. There is a good accessible discussion of this in Weinberg's popular science book 'Dreams of a Final Theory'.
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6. libraryofbabelDec 2017
   I've always liked the dog analogy ever since I came across it in Stephen Weinberg's book Dreams of a Final Theory:

   "...it may be that humans are simply not intelligent enough to discover or to understand the final theory. It is possible to train dogs to do all sorts of clever things, but I doubt that anyone will ever train a dog to use quantum mechanics to calculate atomic energy levels."

   The impossibility of dogs doing Calculus is an equally nice example, but I think we could push the point further. Calculus is not only hard and unnatural for dogs; it is hard and unnatural for humans as well. There were anatomically modern humans equipped with culture and language for something like 30,000 years before even one of them understood calculus. It's truly extraordinary that this thing which was at the absolute limits of the human intellect in the 17th century is now taught routinely in high schools and colleges across the world, and used for such mundane purposes as building bridges or stock trading.

   Those inclined to optimism could read in this a story about how humans are not like dogs, because culture. (i.e.: "culture allows us to consolidate and simply the understanding of previous generations so future generations can build on it towards almost limitless horizons", etc.). But I'm a pessimist: calculus is still damn hard for nearly all human beings (just ask your average college student). Heck, I found it pretty tough to learn and I ended up getting a masters in math. And - to get back to the article - I'm not convinced that current topics at the edge of human understanding today (string theory, or whatever) are ever going to get 'mundane'. It takes many years of special training and extraordinarily single-minded dedication to even get to the current frontier of knowledge in these areas. At some point, as the article says, perhaps the math just gets too hard.

   Fortunately, just because the universe might not be comprehensible by humans (we never get to a successful theory of quantum gravity, or whatever) doesn't mean science itself will have a end. There's plenty to do in other fields.

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