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1500 questions
36
votes
4 answers
How to imagine WiFi signal propagation?
When thinking about how the WiFi signal propagates through a household, can I use the following thought experiment?
Assume absolute darkness. Place a strong lightbulb where the WiFi access point is. The illumination that reaches various places in…
vektor
- 382
36
votes
4 answers
Why have our eyes not evolved to see "gluons"?
The photons are the propagators for QED, and we rely on photons to see the world around us.
The gluon is the propagator in QCD. Why have our eyes not evolved to see gluons (either on top of being able to "see" photons, or instead of)?
DarthPlagueis
- 1,634
36
votes
4 answers
Why doesn't the solar wind disrupt the planets?
The sun creates this heliosphere by sending a constant flow of particles and a magnetic field out into space at over 670,000 miles per hour, which is also known as solar wind. If the speed of the wind is that great, why doesn't it disrupt the…
Tammy Chong
- 539
36
votes
8 answers
Why can't we see light travelling from point A to B?
Let's say we have a cloud of dust which is a lightyear across and someone shoots a beam of light from point A to B , why it is not possible for an observer far far away to see the light while it travels through the cloud at the speed of light?
Zer01
- 395
36
votes
2 answers
Kubo Formula for Quantum Hall Effect
I'm trying to understand the Kubo Formula for the electrical conductivity in the context of the Quantum Hall Effect.
My problem is that several papers, for instance the famous TKNN (1982) paper, or an elaboration by Kohmoto (1984), write the…
Greg Graviton
- 5,157
36
votes
8 answers
Why singularity in a black hole, and not just "very dense"?
Why does there have to be a singularity in a black hole, and not just a very dense lump of matter of finite size? If there's any such thing as granularity of space, couldn't the "singularity" be just the smallest possible size?
Per
- 510
36
votes
5 answers
Why do all the atoms of a radioactive substance not decay at the same time?
Why does the substance decay at a rate which is proportional to the amount of the substance at that moment?
As all atoms are in hurry to become a stable atom and as their decay do not depend on any external things (like pressure, decaying of…
Sanjib Ray
- 409
36
votes
4 answers
Why do we need complex representations in Grand Unified Theories?
EDIT4: I think I was now able to track down where this dogma originally came from. Howard
Georgi wrote in TOWARDS
A
GRAND
UNIFIED
THEORY
OF
FLAVOR
There is a deeper reason to require the fermion
representation to be complex …
jak
- 9,937
- 4
- 35
- 106
36
votes
14 answers
Why does the (relativistic) mass of an object increase when its speed approaches that of light?
I'm reading Nano: The Essentials by T. Pradeep and I came upon this statement in the section explaining the basics of scanning electron microscopy.
However, the equation breaks down when the electron velocity approaches the speed of light as mass…
Kit
- 1,483
36
votes
6 answers
What is the math knowledge necessary for starting Quantum Mechanics?
Could someone experienced in the field tell me what the minimal math knowledge one must obtain in order to grasp the introductory Quantum Mechanics book/course?
I do have math knowledge but I must say, currently, kind of a poor one. I did a basic…
azerIO
- 163
36
votes
5 answers
Why is the nucleus so small and why is the atom 99.999% empty space?
A nucleus consists of protons and neutrons. Both are extremely heavy compared to electrons. Then how come they are contained within an extremely tiny space? And why does the atom consist of 99.999% empty space?
I do not understand the mathematics…
Shades88
- 461
36
votes
7 answers
Conservation of energy and Doppler effect?
From what I understand, the frequency of light coming from a source moving towards an observer increases. From $ E=h\nu $ , this implies an increase in the energy of each photon.
What really is confusing, is where does that extra energy come from?…
S L
- 1,531
36
votes
16 answers
"Reality" of length contraction in SR
I was in argument with someone who claims that length contraction is not "real" but only "apparent", that the measurement of a solid rod in its rest reference frame is the "real length" of the rod and all other measurements are somehow just…
Frank
- 3,403
36
votes
3 answers
Can all fundamental forces be fictitious forces?
After reading many questions, like
this and this, I wonder:
Is it possible to consider the other fundamental forces too, the electroweak interaction and the strong interaction or ultimately the unification of these, to be fictitious forces like…
Costantino
- 985
36
votes
4 answers
What would happen if an accelerated particle collided with a person?
What would happen if an accelerated particle (like they create in the LHC) hit a person standing in its path?
Would the person die? Would the particle rip a hole? Would the particle leave such a tiny wound that it would heal right away? Something…
user60228