Earlier quoted context omitted.
Good to know the speed of light in a vacuum is not a fundamental constant.
Apparently, even vacuum is not a fundamental constant.
The bad news is Nature abhors a vacuum. The good news is there's plenty of it.
A 9-line summary of textbook physics
121–130 of 179 posts
Re: A 9-line summary of textbook physics
#122> Lines 1, 2 and 3, together, uniquely determine special and general relativity, cosmology, the Hilbert Lagrangian and Einstein's field equations, as told here. This is a huge exaggeration. For example 1 says "W=∫L" but L is never defined. The definition of L hides a lot of details, in particular that each point of the universe is equivalent, so there is translation invariance that using the Noether's theorem implies…
These kinds of comments block me from doing a physics dive; I don’t know where to start/am worried about starting from a bad point. I don’t know whether to follow some of the trails the linked author has laid out if I want to learn more, whether you’re nitpicking, or whether you’re advocating for a much better approach that starts with the details you say this obfuscates. When I was younger and had more time I’d be w…
One thing about the traditional sequence of physics topics, is that it progresses (more or less) in parallel with the traditional math sequence. So you can get yourself up to speed on both simultaneously.
Also, you don't need to get all the way to the whiz-bang stuff, for it to be both enjoyable and useful. Granted, my degree was 30+ years ago, but today I specialize in designing measurement equipment. If all you end up learning is calculus plus how some mundane things work like circuits and optics, it would hardly be a loss. I don't even claim to understand fundamental stuff like field theory.
There's also a problem with explaining physics: Most of us who claim to understand it (I have a physics degree) have never attempted to explain it or even think about it without math. There's the commonly shared anecdote about physicists trying to grasp the "non calculus based" college physics course, and finding it too complex and baffling to proceed.
Re: A 9-line summary of textbook physics
#123Earlier quoted context omitted.
^—— “How Many Fundamental Constants Are There?” by John Baez
Good to know the speed of light in a vacuum is not a fundamental constant.
Yep, you can just set c=1 and have https://en.wikipedia.org/wiki/Natural_units
Re: A 9-line summary of textbook physics
#124The author is a well-known crank. See post #10 here, for instance: https://www.physicsforums.com/threads/strand-model-published... Proceed with caution.
Indeed, the author's 2000-page online textbook, heavily promoted on the internet, is a classic trap for unwary students.
It looks alright at first: volume I is light on math, but full of neat examples. But it's full of intuitively plausible but slightly wrong statements which fall apart in more general situations, reflecting the author's lack of technical expertise. This problem steadily gets worse: volume IV is an oversimplified introduction to quantum mechanics which contains almost no math, and serious conceptual errors on almost every page. Volume V covers a bizarre mix of particle physics, consciousness, and sexual reproduction. And volume VI is the author's almost math-free personal theory of everything. Because the change is gradual, a student can get seriously misled without noticing, like the proverbial boiling frog.
On HN, people are always asking how to get started self-learning topics like physics. The tragedy is that this has been a completely solved problem for decades: the standard textbooks are excellent. But people don't hear that message because self-promoters pollute the discourse.
Re: A 9-line summary of textbook physics
#125The author is a well-known crank. See post #10 here, for instance: https://www.physicsforums.com/threads/strand-model-published... Proceed with caution.
With several recent PRDs.
The Physical Review is a gigantic set of journals, and like anything of its size, many of its published results are wrong. At this very moment I'm writing a rebuttal to a PRD paper that arrived at nonsensical conclusions due to some basic algebra mistakes.
Re: A 9-line summary of textbook physics
#126s/nature/the simulation/g 1. Total compute capacity is limited and redistributes toward areas of high activity. 2. Processor speed is limited. 3. Mutations are sensibly constrained to prevent overflow. 4. Smallest addressable memory space. 5. No process is ever fully idle. 6. IPC is done using circles. 7. The kernel however operates at the level of spheres, and pointers to pointers to pointers to spheres. 8. There's…
Religion: "God did it" Simulation hypothesis: "God did it, with a computer"
Simulation hypothesis: God did the first simulation with a computer, everything else is a simulation of a simulation.
Re: A 9-line summary of textbook physics
#127s/nature/the simulation/g 1. Total compute capacity is limited and redistributes toward areas of high activity. 2. Processor speed is limited. 3. Mutations are sensibly constrained to prevent overflow. 4. Smallest addressable memory space. 5. No process is ever fully idle. 6. IPC is done using circles. 7. The kernel however operates at the level of spheres, and pointers to pointers to pointers to spheres. 8. There's…
It makes intuitive sense to me that computers are physically constrained in all of the ways (and more) that the universe itself is physically constrained. I don't know why the inclination is to take these fundamental constraints and then say "the universe is in a computer" instead of saying "the computer is in a universe".
Re: A 9-line summary of textbook physics
#128The author is a well-known crank. See post #10 here, for instance: https://www.physicsforums.com/threads/strand-model-published... Proceed with caution.
Indeed, the author's 2000-page online textbook, heavily promoted on the internet, is a classic trap for unwary students. It looks alright at first: volume I is light on math, but full of neat examples. But it's full of intuitively plausible but slightly wrong statements which fall apart in more general situations, reflecting the author's lack of technical expertise. This problem steadily gets worse: volume IV is an o…
[deleted]
Re: A 9-line summary of textbook physics
#129Earlier quoted context omitted.
Religion: "God did it" Simulation hypothesis: "God did it, with a computer"
Simulation hypothesis: God did the first simulation with a computer, everything else is a simulation of a simulation.
Simulation hypothesis: It's simulations all the way down. No gods in sight.
Re: A 9-line summary of textbook physics
#130> Lines 1, 2 and 3, together, uniquely determine special and general relativity, cosmology, the Hilbert Lagrangian and Einstein's field equations, as told here. This is a huge exaggeration. For example 1 says "W=∫L" but L is never defined. The definition of L hides a lot of details, in particular that each point of the universe is equivalent, so there is translation invariance that using the Noether's theorem implies…
These kinds of comments block me from doing a physics dive; I don’t know where to start/am worried about starting from a bad point. I don’t know whether to follow some of the trails the linked author has laid out if I want to learn more, whether you’re nitpicking, or whether you’re advocating for a much better approach that starts with the details you say this obfuscates. When I was younger and had more time I’d be w…
If you want to dive in to physics on your own, a textbook can be a decent starting point. Griffiths is pretty good, although if you’re starting from zero, it’ll be a challenge.