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Comment by cambalache | Hacker News Reader

You wont understand how stuff "works" if you cannot solve problems, at least not in any meaningful sense.If you want a superficial knowledge (Nothing wrong with that) you have youtube channels or there are conceptual physics textbooks for non science majors.

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I have to agree with this. There is no harm in absorbing qualitative accounts of various physics ideas, and that can be very interesting. But you won't really know what it's all about until you swim in the mathematical details. It sort of like listening to somebody describing programming, without ever writing a computer program.

Or like listening to a description of a song. The speaker might tell you the lyrics, even hum the various parts. If the song is simple (corresponding to perhaps simple and interesting facts about our solar system), vocals will give a good rendition of it. But if the song is intricate (like quantum mechanics), without the full band, all you are listening to is a hollow echo of the song.

I disagree. You can grasp the meaning of pv=nrt without memorizing the value of r. You can understand that electrons exist in probability shells without remembering what atomic number the d orbital starts at. You can understand that e=mv^2 is only an approximation that works at low velocities without being able to do a Lorentz transform.

Solving problems doesn’t necessarily mean getting numerical answers. If you don’t know how to apply the equations you list algebraically then you don’t really understand them.

In all my undergrad and graduate level Physics, I don't think I ever used the value of R. The answer has nothing to do with the numerical value--that you can google. It has to do with knowing how to solve the problem.

Though having a grasp of the numbers can help with scale and the often forgotten "does that make any reasonable sense" check.

> You can grasp the meaning of pv=nrt without memorizing the value of r.

Do you actually think that memorizing physical constant values is solving problems?And ,yes, anybody can grasp what PV= nRT means,but what about stuff like: "The average speed of the molecules doubled, what is the temperature now"."Derive the relation between pressure and height for an ideal gas and use it to estimate at which height the atmospheric pressure halves".Interesting stuff like that and not plugging numbers in a formula.

> you can understand that electrons exist in probability shells without remembering what atomic number the d orbital starts at

The d orbital "starts" at n=1. Hydrogen has d orbitals.You are confusing orbital existence with the occupation of them by electrons.

> You can understand that e=mv^2 is only an approximation that works at low velocities without being able to do a Lorentz transform.

The e = mv^2 you propose here is not an actual formula in physics. It is either Ek = (1/2)mv^2 in classical physics, so just kinetic energy, or E =mc^2+mv^2/(1-gamma^2)^(1/2) in special relativity. Which of course at low velocities is approximated by E= mc^2 + 0.5mv^2 the second term being the Ek as calculated in the classical theory.

I think your comment shows beautifully what I meant with my original assertion.

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