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1500 questions
35
votes
5 answers
Why don't we define potential due to a magnetic field?
We define electric potential and gravitational potential and use them quite often to solve problems and explain stuff. But I have never encountered magnetic potential, neither during my study (I am a high-schooler), nor during any discussion on…
user243267
35
votes
3 answers
What is the shape of the upper boundary of water hitting a screen?
When I saw that thing I did not understand how that shape is formed? To be ideal, take a vertical smooth plane. Now aim at the wall with a thin water tube. Then the outer layer forms a "parabolic shape" with stagnation point as focus of it. I found…
Sandesh Goli
- 982
35
votes
10 answers
Are there physical properties that can be used to differentiate stainless steel from copper in a home environment?
So the backstory is that I purchased a reusable drinking straw that is copper coloured, but is advertised to be stainless steel. That got me thinking about whether I could be sure it was one or the other without having access to a laboratory.
I saw…
Kolichikov
- 475
35
votes
6 answers
Is the Higgs boson an elementary particle? If so, why does it decay?
The Higgs boson is an excitation of the Higgs field and is very massive and short lived. It also interacts with the Higgs field and thus is able to experience mass.
Why does it decay if it is supposed to be an elementary particle according to the…
user6760
- 12,980
35
votes
5 answers
Why is argon a noble gas but not, say, beryllium or palladium?
Why is argon a noble gas given that the 3d subshell is still empty?
More generally, why is it that the filling of a p sub-shell makes an element noble rather than s, d, or f sub-shells, or completed n-levels?
Let's start with the prior that in a…
Paul Young
- 3,536
35
votes
2 answers
Is String Theory formulated in flat or curved spacetime?
String Theory is formulated in 10 or 11 (or 26?) dimensions where it is assumed that all of the space dimensions except for 3 (large) space dimensions and 1 time dimension are a compact manifold with very small dimensions. The question is what is…
FrankH
- 10,676
35
votes
5 answers
Couldn't we always redefine units so that inertial mass and gravitational mass are equal?
It is a known fact that inertial and gravitational masses are the same thing, and therefore are numerically equal. This is not an obvious thing, since there are even experiments trying to find a difference between the two kinds of masses. What I…
RenatoRenatoRenato
- 2,327
35
votes
2 answers
Why isn't the GPS location calculated from the Schwarzschild metric?
The GPS uses the flat space light propagation formula to calculate the distance from the source (the satellite) to the receiver (observer on Earth):
$$ d=c \cdot \Delta t$$
where $c$ is the speed of light in Minkowski vacuum, $\Delta t$ is the…
label
- 533
- 4
- 11
35
votes
5 answers
Intuition for multiple temporal dimensions
It’s easy, relatively speaking, to develop an intuition for higher spatial dimensions, usually by induction on familiar lower-dimensional spaces. But I’m having difficulty envisioning a universe with multiple dimensions of time. Even if such a thing…
Jon Purdy
- 477
35
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
- 461
35
votes
4 answers
What is the difference between a spinor and a vector or a tensor?
Why do we call a 1/2 spin particle satisfying the Dirac equation a spinor, and not a vector or a tensor?
Fahim Sharif
- 527
35
votes
5 answers
Can the Schrodinger equation describe planetary motion?
I was asked on an exam whether the Schrodinger equation can be used to describe planetary motion and my answer was "No, because the solutions are wavefunctions which give probabilities but everything can be exactly measured for large objects."
Then…
WarreG
- 909
35
votes
2 answers
Do magnets wear out?
Can a magnet ever wear out or lose strength?
If you break a magnet it (seemingly) gets weaker, but what about from normal use?
Or even very heavy use, like placing 2 magnets facing each other, so that they detract from each other, does that strain…
Welz
- 439
35
votes
4 answers
Why does light of high frequency appear violet?
When people are asked to match monchromatic violet light with an additive mix of basic colours, they (paradoxically) mix in red. In fact, the CIE 1931 color space chromaticity diagram shows this effect begins at about 510nm (greenish-cyan), where…
wnrph
- 1,287
35
votes
3 answers
Emissitivity of copper - Why are copper heatsinks all shiny?
This wikipedia article states that emissivity of polished copper is 0.04, and emissivity of oxidized copper is 0.87 - more than 20x of the polished copper.
So my question is - why are all copper heatsinks shiny and polished?
Wouldn't oxidized copper…
XIII
- 353