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Lesser known but possibly more relevant to most HN readers are Feynman's lectures on computation - https://theswissbay.ch/pdf/Gentoomen%20Library/Extra/Richard... . There's some really great explanations in there of computability, information theory, entropy, thermodynamics, and more. Very little of it is now out-dated.
By Isamu 2026-02-112:32 Apropos of Feynman on computing, the story of his time working at Thinking Machines Corp https://longnow.org/ideas/richard-feynman-and-the-connection...
“For our first seminar he invited John Hopfield, a friend of his from CalTech, to give us a talk on his scheme for building neural networks. In 1983, studying neural networks was about as fashionable as studying ESP, so some people considered John Hopfield a little bit crazy. Richard was certain he would fit right in at Thinking Machines Corporation.”
Interesting, he also talks about quantum computing (a first?): p. 191, "We now go on to consider how such a computer can also be built using the laws of quantum mechanics. We are going to write a Hamiltonian, for a system of interacting parts, which will behave in the same way as a large system in serving as a universal computer."
p. 196: "In general, in quantum mechanics, the outgoing state at time t is eⁱᴴᵗ Ψᵢₙ where Ψᵢₙ is the input state, for a system with Hamiltonian H. To try to find, for a given special time t, the Hamiltonian which will produce M = eⁱᴴᵗ when M is such a product of non-commuting matrices, from some simple property of the matrices themselves, appears to be very difficult.
We realize, however, that at any particular time, if we expand eⁱᴴᵗ out (as 1 + iHt − H²t²⁄2 + …) we'll find the operator H operating an innumerable arbitrary number of times — once, twice, three times, and so forth — and the total state is generated by a superposition of these possibilities. This suggests that we can solve this problem of the composition of these A’s in the following way..."
Feynman is indeed often quoted among the first people to propose the idea of a quantum computer! This talk he gave in ‘81 is among the earliest discussion of why a quantum universe requires a quantum computer to be simulated [1]:
> Can a quantum system be probabilisticaUy simulated by a classical (probabilistic, I'd assume) universal computer? In other words, a computer which will give the same probabilities as the quantum system does. If you take the computer to be the classical kind I've described so far, (not the quantum kind described in the last section) and there're no changes in any laws, and there's no hocus-pocus, the answer is certainly, No! This is called the hidden-variable problem: it is impossible to represent the results of quantum mechanics with a classical universal device.
Another unique lecture is a 1959 one [2] about the potential of nanotechnology (not even a real thing back then). He speaks of directly manipulating atoms and building angstrom-scale engines and microscope with a highly unusual perspective, extremely fascinating for anyone curious about these things and the historical perspective. Even for Feynman’s standards, this was a unique mix of topics and terminology. For context, the structure of DNA has been discovered about 5 years prior, and the first instruments capable of atomic imaging and manipulation are from at least the 80’s.
If you’re captivated by this last one as I was, I can also recommend Greg Bear’s novel “Blood Music”. It doesn’t explore the nanotechnology side much, but the main hook is biological cells as computers. Gets very crazy from there on.
1. https://s2.smu.edu/~mitch/class/5395/papers/feynman-quantum-... 2. https://www.zyvex.com/nanotech/feynman.html
By griffzhowl 2026-02-1118:34 If you're into atomic physics and getting a feel for the intricate structure of the basic processes, the best find I had recently is this MIT course by Wolfgang Ketterle. The first lecture is an informal overview, and he gives vivid and detailed descriptions of the phenomena they can create and control now, like why we see different kinds of thing happening at very low temperatures: the atoms are moving past each other so slowly that it gives their wavefunctions time to overlap and interact, using intersecting lasers to create arrays of dimples in the electromagnetic field to draw in and hold single atoms, this kind of thing. It gives a more tangible insight into the quantum aspects of matter that can otherwise seem inscrutable
https://www.youtube.com/watch?v=Agu68RGaoWM&list=PLUl4u3cNGP...
He also got the Nobel prize in the 90s for making a Bose-Einstein condensate iirc.
By WhitneyLand 2026-02-1115:49 The quote is not suggesting a quantum computer can’t be simulated classically, it can in fact, just slowly, by keeping track of the quantum state where n qubits is 2^n complex amplitudes.
It relates more to the Bell results, that there doesn’t exist a hidden variable system that’s equivalent to QM.
By jesuslop 2026-02-1113:00 IBM (atoms) [1989]: https://en.wikipedia.org/wiki/IBM_%28atoms%29
By dgfl 2026-02-118:35 “There’s plenty of space at the bottom” only really took off in popularity decades later. Feynman’s accomplishments are undeniable, Nobel prize and all, but his celebrity status is given by other aspects of his personality. No Feynman equivalent I can think of is alive today. Perhaps Geoffrey Hinton and his views on the risk of AGI? He’s far from the only one of course.
By richardfeynman 2026-02-114:412 reply indeed there are.
By mkw5053 2026-02-114:14 I was just talking to someone about Feynman's lectures on computation the other day. I really really enjoyed it. That's all.
The Feynman lectures are obviously brilliant but think the computation lectures are probably a better display of Feynman's brilliance. It's quite stunning how up to date they are.
Although that being said the rough outline of a field is usually worked out almost immediately after a consensus forms that it's "real" so to speak.
By chii 2026-02-114:20 The theory of computation hasn't changed a whole lot since those times - and feynman explains it very well to a laymen audience (which is what makes it great, as it's not filled with jargon).
By CaptainNegative 2026-02-116:15 I feel like the section on primality testing with Fermat's test should at least make a shout out to Carmichael numbers and that for some inputs the probability you get a false positive result is 1.
Poets say science takes away from the beauty of the stars—mere globs of gas atoms. Nothing is 'mere.' I too can see the stars on a desert night, and feel them. But do I see less or more? The vastness of the heavens stretches my imagination—stuck on this carousel my little eye can catch one-million-year-old light. A vast pattern—of which I am a part—perhaps my stuff was belched from some forgotten star, as one is belching there. Or see them with the greater eye of Palomar, rushing all apart from some common starting point when they were perhaps all together. What is the pattern, or the meaning, or the why? It does not do harm to the mystery to know a little about it. For far more marvelous is the truth than any artists of the past imagined! Why do the poets of the present not speak of it? What men are poets who can speak of Jupiter if he were like a man, but if he is an immense spinning sphere of methane and ammonia must be silent?By rramadass 2026-02-113:53 The man had a way with words.
The recent HN thread Why is the sky blue? is a good example of this - https://news.ycombinator.com/item?id=46946401
Once you start going down the rabbit hole you start asking questions like "does the photon oscillate?", "what exactly is resonant frequency?", "how different is the electron cloud around a molecule from that around its constituent atoms?", "how does a photon passing by/through a molecule cause its electron cloud to oscillate?" etc. The act of clarifying each to oneself in however simple a form is the insight we all crave. Good teachers like Feynman do a great job of it which is why their books are so highly valued.
PS: People might find the recent free book Atomic Physics for Everyone: An Introduction to Atomic Physics, Quantum Mechanics, and Precision Spectroscopy with No College-Level Prerequisites (2025) good for an initial understanding of atomic physics - https://news.ycombinator.com/item?id=46961595
By shanemhansen 2026-02-113:292 reply I've thought of this quote a bunch and I came up with my own addon.
"Some people think that the magic of something wondrous is diminished when it's understood. I feel bad for those people." -- Shanemhansen
By mananaysiempre 2026-02-111:381 reply A footnote for those of the millenial or more recent persuasion: we take the full “vastness of the heavens” as given, as we’ve seen it described pretty confidently all the way back to the science books of our childhood. But cosmology, and frankly the entire field of astrophysics, is strikingly young. The idea that nebulae are in fact whole independent collections of stars, and that the observable universe is large enough to accomodate all of that, is younger than quantum mechanics and relativity both, and only got acceptance after a huge fight. The name “Big Bang” was originally a pejorative used in a similar, later fight. And so on. When Feynman said this, the idea of nebulae as galaxies was younger (~40 years) than the key idea of quarks (confinement/asymptotic freedom) is today (~50 years), and I’m guessing the latter still counts as new and arcane in your mind.
I feel uncomfortable labelling nebulae as collection of stars. The more appropriate term is stellar nursery if you want to allude to their role in star formation.
They themselves are just clouds of gas and dust where protostars have begun to form.
Stellar clusters are what you would call a collection of stars.
Also on the note of cosmology and astrophysics being strikingly young fields, I think that's fair statement if we consider their modern definitions. Although their core ideas have already been discussed in a lot of ancient civilizations. It was a lot more philosophical and less rooted in science though (except for the observational astronomy, which remains perhaps one of the oldest scientific discipline).
By mananaysiempre 2026-02-113:361 reply Sorry, yes, there’s a terminological disconnect here: M31, say, is the “Andromeda Galaxy” to us, but the “Andromeda Nebula” to Hubble’s contemporaries circa 1920. The recognition that at least some of the cloudy (nebulous, literally) stuff in the sky is galaxies (and that the universe fits more than one) was the very point of the fight I mentioned. The world before it was thought to be drastically smaller in a way that I find difficult to think about.
By kmaitreys 2026-02-114:25 That's right. Historically, nebula was anything that looked cloudy, so a lot of astrophysical objects that we now understand are distinct, were simply labelled as nebulous. M31, as you said, being a great example.
Modern astrophysics still carries the baggage of obsolete terminology to this day, from names of objects to names of units.
By haroldp 2026-02-114:20
Unlike the commercial audio CDs of the lectures the recordings here have the chat before and after the lecture which is fun.
My favourite lecture is the standalone "The Principle of Least Action" at
https://www.feynmanlectures.caltech.edu/II_19.html
Audio: https://www.feynmanlectures.caltech.edu/II_19.html#Ch19-audi...
By ontouchstart 2026-02-1111:43 This one is my favorite too. I had the three volumes of hardcover copy.
> Later chapters do not depend on the material of this special lecture—which is intended to be for “entertainment”
We might say this is the most important chapter in the whole series.
