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A 9-line summary of textbook physics

motionmountain.net

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Re: A 9-line summary of textbook physics

#61

Post by PrettyPebble »

erikpukinskis wrote: post #17
PrettyPebble wrote: post #2

Fun fact: all physics experiments ever made can be described by 9 lines, without any deviation between theory and observations. The 9 lines are sufficient to describe quantum physics and gravity. It seems that the 9 lines even contain all (update: natural) sciences, not only physics. Finding an exception to the 9 lines will make you famous. So will the discovery of a 10th line. Thousands of researchers work towards t…

This is just straight wrong. There is no computer in the world that can predict the outcome of, say, a drug trial from these equations. If your “science” requires an impossible computer to work then it’s not science it’s faith.

The 9 lines do not say this. The lines do say that drugs are made of atoms and that the molecules follow quantum theory.

Re: A 9-line summary of textbook physics

#62

Post by podiki »

323 wrote: post #41

I've read a few times that you can derive the Maxwell equations from knowing that U(1) exists, as this article implies, that every point in space has (among other things) the symmetry of a circle. But I've never seen this derivation. I assume it's either trivial or too complicated. Anyone has a link or thoughts on this?

In short, if you impose a U(1) symmetry on your Lagrangian, you get electromagnetism. Basically you do the action of U(1) and enforce that the equation of motion does not change. That gives you the electromagnetic force (a photon).

Putting in some of those keywords will find plenty of detailed notes online, like

http://www.physics.usu.edu/torre/Classical_Field_Theory/Lect...

or more quick overviews like

https://mugndonut.wordpress.com/2018/03/31/symmetries-yield-...

Re: A 9-line summary of textbook physics

#63

Post by PrettyPebble »

criticaltinker wrote: post #15
PrettyPebble wrote: post #2

Fun fact: all physics experiments ever made can be described by 9 lines, without any deviation between theory and observations. The 9 lines are sufficient to describe quantum physics and gravity. It seems that the 9 lines even contain all (update: natural) sciences, not only physics. Finding an exception to the 9 lines will make you famous. So will the discovery of a 10th line. Thousands of researchers work towards t…

This is satire right? You might be getting downvotes because it’s not clear if you’re serious, and those claims seem quite ridiculous at face value.

What is ridiculous?

Re: A 9-line summary of textbook physics

#64

Post by mhh__ »

ravi-delia wrote: post #37
mhh__ wrote: post #23

The 9 equations aspect is pretty pointless but the chapters on the right hand side could be ok. One of the things that makes physics different to most subjects is that we can make an explicit goal of being smug and rederiving the laws of physics from the simplest possible principles. I think the book seems to do this, but just summarizing like done on this webpage is a bit daft.

I think the way these are phrased do a better job expressing the "vibe", for lack of a better word, of our current understanding. That the particles and constants are declared by fiat, with behavior constrained by simpler laws, is an understanding I didn't come to until I took a QFT course. The physicist's God is as concerned with forbidding seemingly pointless things as the biologist's God is with beetles.

Vibe is not a bad word to use in these situations.

Re: A 9-line summary of textbook physics

#65

Post by user-the-name »

PrettyPebble wrote: post #58
gus_massa wrote: post #55

> 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…

For deriving special and general relativity, see https://www.motionmountain.net/maximumforce.html The page also cites the papers proving the statement.

That page has zero words about actually deriving anything.

Re: A 9-line summary of textbook physics

#66

Post by PrettyPebble »

ianbooker wrote: post #32
PrettyPebble wrote: post #21

Earlier quoted context omitted.

Good point - but it needs computers...

Strangely not. You can do CS on paper, no need for a single bit-flipping device. Turing did half the field in his head / a thought experiment.

And input and ouput devices ...

Re: A 9-line summary of textbook physics

#67

Post by theduder99 »

la64710 wrote: post #35

Why do the first chapters of all physics textbook ONLY talk about Greek philosophers and scientists and NEVER talk about contribution to Science from eastern civilization like India and China ? These civilizations have a very rich heritage and astounding contribution to many underlying scientific philosophies. Yet generation after generation of writers ignore them and it is sad to see that being true even today. It i…

can you recommend me some good books on China and India's contributions to Science please?

Re: A 9-line summary of textbook physics

#68

Post by 7373737373 »

MauranKilom wrote: post #9

> About 18 particles > About 25 numbers Excellent science here!

https://math.ucr.edu/home/baez/constants.html

  the mass of the up quark
  the mass of the down quark
  the mass of the charmed quark
  the mass of the strange quark
  the mass of the top quark
  the mass of the bottom quark
  4 numbers for the Kobayashi-Maskawa matrix
  the mass of the electron
  the mass of the electron neutrino
  the mass of the muon
  the mass of the mu neutrino
  the mass of the tau
  the mass of the tau neutrino
  4 numbers for the Pontecorvo-Maki-Nakagawa-Sakata matrix
  the mass of the Higgs boson
  the expectation value of the Higgs field
  the U(1) coupling constant
  the SU(2) coupling constant
  the strong coupling constant
  the cosmological constant

Re: A 9-line summary of textbook physics

#69

Post by dgellow »

sdoering wrote: post #26
Reventlov wrote: post #6

I opened a volume of the books linked in the page, and found this: « Learning allows us to discover what kind of person we can be. Learning widens knowledge, improves intelligence and provides a sense of achievement. Therefore, learning from a book, especially one about nature, should be efficient and enjoyable. Avoid bad learning methods like the plague! Do not use a marker, a pen or a pencil to highlight or underli…

> Do not use a marker, a pen or a pencil to highlight or underline text on paper. It is a waste of time, provides false comfort and makes the text unreadable. What a load of elitist BS (pardon my French). When I was at University we were trained early on to cut the notion of a book being sacred. We should mark, note, create meaning on the pages with pens. I would not have been able to learn as much in my life if I ha…

> What a load of elitist BS (pardon my French)

The actual French word would be "conneries" (in plural here).

Re: A 9-line summary of textbook physics

#70

Post by irrational »

Reventlov wrote: post #6

I opened a volume of the books linked in the page, and found this: « Learning allows us to discover what kind of person we can be. Learning widens knowledge, improves intelligence and provides a sense of achievement. Therefore, learning from a book, especially one about nature, should be efficient and enjoyable. Avoid bad learning methods like the plague! Do not use a marker, a pen or a pencil to highlight or underli…

Yeah, this is clearly BS. Recently I changed the turn switch on my car. How did I learn how to do that? From the Internet, specifically from watching videos. It was easily the most efficient way to learn.
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