151–160 of 179 posts
Can somebody with knowledge in biology and/or physics take a look at (one of) his book and comment if it's decent as in if the science is solid? I browsed https://www.motionmountain.net/motionmountain-volume5.pdf and I'm intrigued (there are no reviews in Amazon).
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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…
> the standard textbooks are excellent Sorry, I have to disagree with this, at least with respect to quantum mechanics. The pedagogy of QM is atrocious because it generally focuses on the single-particle case and relegates entanglement to the sidelines while making a big deal out of the mystery of the measurement problem. This leaves students hopelessly confused. At least, it left me hopelessly confused for about ten…
And is the measurement problem not a mystery? If there's convincing explanation, that's news to me.
Earlier quoted context omitted.
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…
What are the standard textbooks? Could I just look at the curriculum of any physics program of a respected school and go from there?
Earlier quoted context omitted.
> the standard textbooks are excellent Sorry, I have to disagree with this, at least with respect to quantum mechanics. The pedagogy of QM is atrocious because it generally focuses on the single-particle case and relegates entanglement to the sidelines while making a big deal out of the mystery of the measurement problem. This leaves students hopelessly confused. At least, it left me hopelessly confused for about ten…
Can you point to a standard textbook that does this? The ones I'm familiar with definitely don't shortchange multi-particle problems. And is the measurement problem not a mystery? If there's convincing explanation, that's news to me.
That does what? Focus on the single-particle case and punt on measurement? My two poster children are the Feynman lectures and Griffiths.
> The ones I'm familiar with definitely don't shortchange multi-particle problems.
What does your reading list look like? Maybe things have changed since I last looked.
> the measurement problem not a mystery?
It might be a mystery, but it is not the mystery most commonly presented, namely, that particles change their behavior "when somebody looks." This is nonsense. Measurement has nothing to do with "somebody looking", it is just entanglement + decoherence. The only real mystery is the origin of the Born probabilities.
See https://flownet.com/ron/QM.pdf for a complete discussion.
> 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…
I will always be amused when people who study particle physics do everything after 2nd quantization and thus assume that literally understanding plane wave interactions explain all physics, rather than such methods are actually reductionist and have their own attendant assumptions that fail at certain points (like the UV limit for QED), but that means you really don't "understand" all physics just by writing down the Lagrangian for SM, it's just a starting point. "Understand" for a scientist shouldn't be abstract, it should be "given x equations/model I can predict y output" which is very hard for a lot of physics, otherwise there wouldn't millions of scientists doing things other that just doing string theory derivations everyday.
Equations of motion is not understanding.
I'm a former physics/astro person, and honestly I had never seen a factor like c^4 power in my life...
Huh? It appears in the basic relativistic energy/momentum equation at the bottom of here http://hyperphysics.phy-astr.gsu.edu/hbase/Relativ/relmom.ht...
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Can you point to a standard textbook that does this? The ones I'm familiar with definitely don't shortchange multi-particle problems. And is the measurement problem not a mystery? If there's convincing explanation, that's news to me.
> Can you point to a standard textbook that does this? That does what? Focus on the single-particle case and punt on measurement? My two poster children are the Feynman lectures and Griffiths. > The ones I'm familiar with definitely don't shortchange multi-particle problems. What does your reading list look like? Maybe things have changed since I last looked. > the measurement problem not a mystery? It might be a mys…
Concerning Griffiths, what do you feel it lacks? You've got the hydrogen atom, fermions, bosons, helium, and probably more stuff that I'm forgetting right now. What else would you stick in an intro course? Hartree-Fock?
B) Decoherence doesn't solve the measurement problem. Even the decoherence boosters admit this. See, for example, Adler's paper on this: https://arxiv.org/abs/quant-ph/0112095.
This isn't to say the decoherence program isn't important. I think it is. It just hasn't solved the measurement problem.
The empty space between the bosons, quarks and leptons is not made up of any of these particles, yet the space ‘exists’ - without it, everything in the universe would just be a big clump.
> 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…
There is a very good starting point following the historic developments, maybe iron age stuff, a bit of platonic philosophy, including logic, rhethorics and philology on an a-level level. purely theoretical physics is rather math heavy final year, post grad stuff.
> 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…
In GR you maximize proper time to get geodesics.