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1500 questions
38
votes
2 answers
Does too little ice make my martinis watery?
When I make martinis, the recipe I use is 2.5 fluid ounces1 of gin2 and 1/2 fluid ounce dry vermouth3, shaken or stirred4 with 7 ice cubes5, then strained into a cocktail glass (I mix until it's cold enough, and not for some specific length of…
bmb
- 461
38
votes
4 answers
Is there just one EM field for the whole universe?
Does our universe contain individual magnetic fields ?
For example two different magnets, one here on earth and one on mars. Do both of them have their own magnetic field? Or is there only one single field that stretches across the entire universe,…
user134652
38
votes
1 answer
Is there an elegant proof of the existence of Majorana spinors?
Almost all standard sources on the existence of Majorana spinors (e.g. Appendix B.1 to Polchinski's "String Theory", Vol. 2) do so in a way I consider inherently ugly:
A priori, we are dealing with an irreducible complex representation $(V,\rho)$…
ACuriousMind
- 124,833
38
votes
5 answers
Is the Schrödinger equation derived or postulated?
I'm an undergraduate mathematics student trying to understand some quantum mechanics, but I'm having a hard time understanding what is the status of the Schrödinger equation.
In some places I've read that it's just a postulate. At least, that's how…
Bruno Stonek
- 751
38
votes
8 answers
Would it matter if the Earth rotated clockwise?
In the Futurama episode "That Darn Katz!" they save the world by rotating the Earth backwards saying it shouldn't matter (which direction Earth rotates). If Earth rotated clockwise and remained in it's current counter-clockwise orbit around the Sun,…
Major Stackings
- 715
38
votes
10 answers
Is there a notion of causality in physical laws?
I was reading "A Few Useful Things to Know about Machine Learning" by Pedro Domingos and towards the end of the paper he makes this statement:
"Many researchers believe that causality is only a convenient fiction. For example, there is no notion of…
covfefe
- 473
38
votes
5 answers
How does defrosting your freezer save energy?
I've been told I should defrost my freezer to save energy, wiki, here and here for example, but none of the linked sites is a peer-reviewed paper explaining why (the wiki article doesn't even have references), and I don't find it obvious. I don't…
Santropedro
- 1,426
38
votes
7 answers
How fast a (relatively) small black hole will consume the Earth?
This question appeared quite a time ago and was inspired, of course, by all the fuss around "LHC will destroy the Earth".
Consider a small black hole, that is somehow got inside the Earth. Under "small" I mean small enough to not to destroy Earth…
Kostya
- 19,992
38
votes
4 answers
Are today's chip scale atomic clocks accurate enough to conduct my own test of time dilation?
Regarding the Symmetricom SA.45s Quantum™ Chip Scale Atomic Clock, is it accurate enough to test time dilation if I place one at sea level, and one on a mountain? It's accurate to 3.0⋅10−10 per month.
Steve
- 521
38
votes
11 answers
Examples of number theory showing up in physics
Are there any interesting examples of number theory showing up unexpectedly in physics?
This probably sounds like rather strange question, or rather like one of the trivial to ask but often unhelpful questions like "give some examples of topic A…
Joe Fitzsimons
- 8,425
38
votes
10 answers
A contradiction between Biot-Savart and Ampère-Maxwell Laws?
I came across a problem that I cannot get my head around.
Consider two very small spherical metallic balls given charges $+Q$ and $-Q$. Assume that both can be approximated as point charges. Now, they are connected by a straight, finite, conducting…
Newton
- 787
38
votes
3 answers
The exchange of photons gives rise to the electromagnetic force
Pardon me for my stubborn classical/semiclassical brain. But I bet I am not the only one finding such description confusing.
If EM force is caused by the exchange of photons, does that mean only when there are photons exchanged shall there be a…
skywaddler
- 1,485
38
votes
3 answers
What happens when anti-matter falls into a black hole?
Let's say a black hole of mass $M$ and a very compact lump of anti-matter (not a singularity) also of mass $M$ are traveling toward each other. What does an outside observer see when they meet?
Will they blow themselves apart in a …
Schwern
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38
votes
8 answers
Does the scientific community consider the Loschmidt paradox resolved? If so what is the resolution?
Does the scientific community consider the Loschmidt paradox resolved? If so what is the resolution?
I have never seen dissipation explained, although what I have seen a lot is descriptions of dissipation (i.e. more detailed pathways/mechanisms for…
propaganda
- 928
38
votes
5 answers
How are forces "mediated"?
I hope this is the right word to use.
To me, these forces seem kind of fanciful (except for General Relativity and Gravity, which have a geometric interpretation).
For example, how do two charged particles know that they are to move apart from each…
Justin L.
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