Questions tagged [faq]
Frequently asked questions. Whenever the same question winds up getting asked over and over again, this tag should designate the _original_ one, which we close all the others as duplicates of.
29 questions
0 votes
6 answers
773 views
Why does it represent change in velocity?
In the above image a particle goes with velocity $v_0$ at some direction and then in an another direction where its velocity is represented by $v$. Both are same in magnitude but their direction is ...
- 1,138
38 votes
3 answers
2k views
Is it possible to speak about changes in a physical constant which is not dimensionless?
Every so often, one sees on this site* or in the news† or in journal articles‡ a statement of the form "we have measured a change in such-and-such fundamental constant" (or, perhaps more commonly, "we ...
- 138k
14 votes
1 answer
7k views
How do Einstein's field equations come out of string theory?
The classical theory of spacetime geometry that we call gravity is described at its core by the Einstein field equations, which relate the curvature of spacetime to the distribution of matter and ...
- 1,031
29 votes
3 answers
17k views
How does the Higgs Boson gain mass itself?
If the Higgs field gives mass to particles, and the Higgs boson itself has mass, does this mean there is some kind of self-interaction? Also, does the Higgs Boson have zero rest mass and so move at ...
- 14.7k
27 votes
7 answers
7k views
Is it possible to recover Classical Mechanics from Schrödinger's equation?
Let me explain in details. Let $\Psi=\Psi(x,t)$ be the wave function of a particle moving in a unidimensional space. Is there a way of writing $\Psi(x,t)$ so that $|\Psi(x,t)|^2$ represents the ...
304 votes
1 answer
152k views
Resource recommendations [closed]
Every once in a while, we get a question asking for a book or other educational reference on a particular topic at a particular level. This is a meta-question that collects all those links together. ...
72 votes
17 answers
144k views
What is the simplest way to prove the Earth is round?
Assume you've come in contact with a tribe of people cut off from the rest of the world, or you've gone back in time several thousand years, or (more likely) you've got a numbskull cousin. How would ...
tQuarella
22 votes
9 answers
26k views
Why there's a whirl when you drain the bathtub?
At first I thought it's because of Coriolis, but then someone told me that at the bathtub scale that's not the predominant force in this phenomenon.
- 363