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1500 questions
81
votes
7 answers
Which way does the scale tip?
I found the problem described in the attached picture on the internet. In the comment sections there were two opposing solutions. So it made me wonder which of those would be the actual solution.
So basically the question would be the following.…
Peter Raeves
- 923
81
votes
8 answers
Moon's pull causes tides on far side of Earth: why?
I have always wondered and once I even got it, but then completely forgot. I understand that gravity causes high and low tides in oceans, but why does it occur on the other side of Earth?
Muhammad Umer
- 2,635
81
votes
6 answers
What was the major discovery on gravitational waves made March 17th, 2014, in the BICEP2 experiment?
The Harvard-Smithsonian Centre for Astrophysics held a press conference today to announce a major discovery relating to gravitational waves. What was their announcement, and what are the implications?
Would this discovery be confirmation of…
Physics_maths
- 5,559
80
votes
3 answers
Why is the sky not purple?
I realise the question of why this sky is blue is considered reasonably often here, one way or another. You can take that knowledge as given. What I'm wondering is, given that the spectrum of Rayleigh scattering goes like $\omega^4$, why is the…
Warrick
- 9,625
80
votes
2 answers
Why did Feynman's thesis almost work?
A bit of background helps frame this question. The question itself is in the last sentence.
For his PhD thesis, Richard Feynman and his thesis adviser John Archibald Wheeler devised an astonishingly strange approach to explaining electron-electron…
Terry Bollinger
- 21,997
80
votes
11 answers
What determines color -- wavelength or frequency?
What determines the color of light -- is it the wavelength of the light or the frequency?
(i.e. If you put light through a medium other than air, in order to keep its color the same, which one would you need to keep constant: the wavelength or the…
user541686
- 4,131
80
votes
5 answers
Understanding the Bloch sphere
It is usually said that the points on the surface of the Bloch sphere represent the pure states of a single 2-level quantum system. A pure state being of the form:
$$
|\psi\rangle = a |0\rangle+b |1\rangle
$$
And typically the north and south poles…
user098876
- 1,601
80
votes
8 answers
Why is there no absolute maximum temperature?
If temperature makes particles vibrate faster, and movement is limited by the speed of light, then I would assume that temperature must be limited as well.
Why is there no limit?
serg
- 1,435
80
votes
5 answers
How literally should you take "The Higgs boson gives other particles mass"?
A standard phrase in popular discussions of the Higgs boson is that "it gives particles mass". To what extent is this a reasonable, pop-science, level of description of the Higgs boson and it's relationship to particles' masses?
Is this phrasing…
Dave
- 4,153
79
votes
7 answers
Does Coulomb's Law, with Gauss's Law, imply the existence of only three spatial dimensions?
Coulomb's Law states that the fall-off of the strength of the electrostatic force is inversely proportional to the distance squared of the charges.
Gauss's law implies that the total flux through a surface completely enclosing a charge is…
Justin L.
- 5,980
- 6
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- 51
79
votes
5 answers
What causes ballpoint pens to write intermittently?
After a while, a ball point pen doesn't write very well anymore. It will write for a little distance, then leave a gap, then maybe write in little streaks, then maybe write properly again. It seems to be worse with older pens, but I have observed…
Olin Lathrop
- 12,916
- 1
- 31
- 47
79
votes
5 answers
Why can we distinguish different pitches in a chord but not different hues of light?
In music, when two or more pitches are played together at the same time, they form a chord. If each pitch has a corresponding wave frequency (a pure, or fundamental, tone), the pitches played together make a superposition waveform, which is obtained…
chharvey
- 868
79
votes
1 answer
Why does soaking a fabric make it more transparent?
It's a well-known fact that when one soaks a thin piece of fabric, it will often become more transparent than it was before.
What is the reason behind this? I can't put glass behind the fabric and increase its transparency.
(Also, just in case this…
Isky Mathews
- 1,935
79
votes
16 answers
How exactly does curved space-time describe the force of gravity?
I understand that people explain (in layman's terms at least) that the presence of mass "warps" space-time geometry, and this causes gravity. I have also of course heard the analogy of a blanket or trampoline bending under an object, which causes…
Zac
- 893
79
votes
3 answers
Why do we need to "create our own" Higgs boson in order to see one?
I understand that the LHC found the Higgs boson by pumping so much energy into a tiny space (via near light speed proton-proton collisions) that a Higgs boson appeared momentarily, then instantly decayed. They detected the products of the decay, and…
Max Williams
- 1,309