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1500 questions
37
votes
4 answers
Entropy and the principle of least action
Is there any link between the law of maximum entropy and the principle of least action. Is it possible to derive one from the other?
Anarchasis
- 1,397
37
votes
6 answers
What is the probability for an electron of an atom on Earth to lie outside the galaxy?
In this youtube video it is claimed that electrons orbit their atom's nucleus not in well-known fixed orbits, but within "clouds of probability", i.e., spaces around the nucleus where they can lie with a probability of 95%, called "orbitals".
It is…
Klangen
- 479
37
votes
3 answers
Why is there more steam after a pot of water *stops* boiling?
I have a pot of vigorously boiling water on a gas stove. There's some steam, but not alot. When I turn off the gas, the boiling immediately subsides, and a huge waft of steam comes out. This is followed by a steady output of steam that's greater…
SuperElectric
- 481
37
votes
7 answers
Reading list in topological QFT
I'm interested in learning about topological QFT including Chern Simons theory, Jones polynomial, Donaldson theory and Floer homology - basically the kind of things Witten worked on in the 80s. I'm looking for pedagogical reviews rather than…
Sudip Paul
- 771
37
votes
1 answer
Can I eat myself into a black hole?
This was a humorous thought experiment that occurred while chatting about black holes. The person that I was talking to assumed that a black hole required a specific density to be achieved. I pointed to the formula for the Schwarzschild radius. …
badjohn
- 2,095
37
votes
3 answers
Could a powerful gravitational wave cause electrons to emit light?
I imagine electrons being accelerated by passing gravitational waves, say from a nearby kilonova, so I would expect the electrons to emit light. Am I right?
user6760
- 13,214
37
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6 answers
How many times has the matter in our Solar System been recycled from previous stars?
I've got a basic understanding of these facts:
The Universe is a little over 13 billion years old. Our Galaxy is almost that old.
Our Solar System is roughly 4.6 billion years old.
The heavier elements (carbon, oxygen, etc...) are only produced by…
Clinton Pierce
- 473
37
votes
3 answers
Nuclear Fusion: Why is spherical magnetic confinement not used instead of tokamaks in nuclear fusion?
In nuclear fusion, the goal is to create and sustain (usually with magnetic fields) a high-temperature and high-pressure environment enough to output more energy than put in.
Tokamaks (donut shape) have been the topology of choice for many years.…
Valentina
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37
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7 answers
Dirac once said that renormalization is just a stop gap procedure, and there had to occur a fundamental change in our ideas. Did something change?
Once, Dirac said the following about renormalization in Quantum Field Theory (look here, for example):
Renormalization is just a stop-gap procedure. There must be some fundamental change in our ideas, probably a change just as fundamental as the…
Deschele Schilder
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37
votes
1 answer
How far away are we from probing Planck scale physics directly?
There are three related questions here:
Given the current limits of technology how far away are we from probing Planck scale physics directly?
It's well known, at least in some circles, that atoms were thought of in Antiquity; given the limits of…
Mozibur Ullah
- 14,713
37
votes
3 answers
Does QED really break down at the Landau pole?
In QED, the fine structure constant $\alpha$ runs upwards in the UV, with a loop calculation (involving a geometric series of the vacuum polarisation diagram) indicating a divergence in $\alpha$ at $\sim 10^{286}\,\text{eV}$. It is often claimed…
gj255
- 6,525
37
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
- 459
37
votes
4 answers
If temperature is amount of kinetic energy of particles, then how can there be a cold breeze?
When we put hands on A/C it gives cold winds. These winds have high kinetic energy but low temperature. How ? *don't confuse with A/C being heat pump , just an example, take antarctic blizzards. I can't understand the paradox of low temperature…
user37060
- 451
37
votes
3 answers
Why do nuclei decay so fast and slow?
Why do nuclei like Oganesson (also known as Ununoctium, this is the 118th element on the periodic table) decay in about 5 milliseconds? This is weird that they decay. In comparison, why do elements like uranium take about 200,000 years to decay, or…
science error
- 339
37
votes
6 answers
If the moon had a mirror surface, would the earth be equally illuminated as by the sun during full moon, or would it require a different mirror shape?
Suppose the apparent diameters of the sun and the moon are exactly the same (which in fact very close to the real situation). If the moon had a perfect mirror surface, would the reflected visible light of a full moon (at night) illuminate the earth…
Deschele Schilder
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