0
votes
0answers
9 views

Does spin-0 or spin-2 describe massive or massless particles?

spin-0 is massive or massless? How does we separate the massive and massless degrees of freedom for spin-2? What is the partially massive?
1
vote
0answers
6 views

Why would classical correlation in Bell's experiment be a linear function of angle?

Sorry if it's a newbie question, but I have trouble understanding the following part in the Wikipedia's explanation for the Bell's theorem: With the measurements oriented at intermediate angles ...
0
votes
0answers
15 views

F-mu-nu notation [on hold]

This is a really simple question that I cannot find an answer to, strangely enough. What do these (similar) notations stand for: $F^{\mu\nu}$ $F_{\mu}^{\nu}$ $F^{a\mu\nu}$ etc etc.
0
votes
1answer
25 views

Magnetic field of a stationary electron

As far as I know, a magnetic field can only be produced by a moving electric charge, or from a particle's spin (this is how a permanent magnet works, all the spins are in the same direction) What is ...
2
votes
2answers
22 views

Why doesn't water in water barometer boil?

I have read that the pressure in a water barometer at the top of the water column is around 0.5 psi and at such low pressures water should boil at around ~26°C (Room temperature). [1] [2] How ...
0
votes
1answer
21 views

Interaction of solid objects and change of trajectory

I have two solid objects. Each of them has an arbitary complex surface, which is discribed by set of vertices. The aim is to describe their interaction, result of which is the change in trajectory of ...
2
votes
2answers
45 views

Can quarks of different colors annihilate?

Wikipedia: "Antiparticles have exactly opposite additive quantum numbers from particles, so the sums of all quantum numbers of the original pair are zero." Is it possible to annihilate a ...
0
votes
0answers
19 views

Conditions for hyperregularity

(Definitions from Marsden & Ratiu, ``Introduction to Mechanics and Symmetry''): A Lagrangian is regular if the Hessian $\partial^2 L/(\partial \dot{q}^i \partial \dot{q}^j)$ is weakly non ...
2
votes
0answers
15 views

Why is there a 'loophole' in Mermin Wagner for rotations?

I'm just starting out in my mathematics career by looking at some simple stuff on broken symmetries in statistical mechanics. Since 3D is 'hard' it would be very nice to look at 2D toy models of ...
1
vote
2answers
46 views

Could the universe have evolved WITHOUT the non-determinism of quantum mechanics? [on hold]

(I'm going to make a few conjectures here - please answer the question in light of them as if they were true, even though of course they may be overly simplistic or wrong) Assuming that: the ...
5
votes
3answers
43 views

Leading-order cause of diurnal (not semidiurnal) variations in $g$?

The following graph shows the result of a very impressive differential measurement of the gravitational field in Boulder, Colorado, over a period of a couple of days. Floris got it from a ...
0
votes
2answers
60 views

Does Free Will Theorem imply that quantum mechanics plays crucial role in our brain’s functioning (consciousness)?

Is opposite statement of Free Will Theorem right: If elementary particles have a certain amount of free will, then so must we? Because to me elementary particles does have a bit of free will – quantum ...
4
votes
1answer
90 views

Why is fundamental physics taught in terms of particles?

According to this paper, there can be no relativistic quantum theory of localizeable particles ("relativity plus quantum mechanics exclusively requires a field ontology"). Sean Caroll has also argued ...
1
vote
1answer
34 views

Bloch theorem, Energy, Free electron

I'm trying to learn on my own a bit of solid physics to tackle semiconductors afterwards. I'm struggling with the Energy versus $k$ diagrams for a free electron which shows that for a single value of ...
-2
votes
1answer
38 views

When/Where will the planets colide?

Given N bodies of known position, mass, speed and direction, if they were to collide, where it will happen and when? PS: this is not a homework... im working on a physics simulation engine... ...
0
votes
0answers
29 views

Macroscopic Forces from QED

In QED the carrier for electromagnetic interaction is a photon, while macroscopic forces are due to electromagnetic interaction (by macroscopic forces I mean: normal force, object collision, friction ...
3
votes
2answers
55 views

How can a detector distinguish between a photon and a gluon

Considering that both gluons and photons have no mass, no charge and spin 1, I was wondering how one can tell the difference, if they hit a detector after a collision at the LHC. I know that gluons ...
1
vote
0answers
7 views

scattering matrix superccurent density of states

while studying scattering formula for the supercurrent (Beenakker) I encountered that the density of states for discrete and continuous spectrum can be simultaneously described by taking $\epsilon\ ...
-2
votes
0answers
22 views

Determine unknown potential & Hamiltonian in Schrödinger equation [on hold]

$x$ - time dependent Cartesian coordinate ; $m$ - time dependent mass of particle; Potential energy - unknown ! Hamiltonian - unknown ! Tasks: Make a formula to predict the $X(t$) ($x(t)$ for ...
1
vote
2answers
38 views

Can we correctly define momentum operator only by means of position operator and their commutation relation?

In "J.M. Ziman. Electrons and Phonons: The Theory of Transport Phenomena in Solids" the author formally introduces the position (displacement) operator and then defines the momentum operator with the ...
0
votes
0answers
9 views

Chemical potentials for multicomponent solids

I have a problem understanding how to deal with the chemical potential when two thermodynamic systems are in contact. For simplicity, let us consider $T=0\ K$. We have a system that is composed of two ...
6
votes
4answers
762 views

How much red, blue and green does white light have?

Different kinds of white light have a different spectrum. Light from a white LED will have blue at the peak intensity while white light from a CFL or something else will have a different looking ...
0
votes
0answers
11 views

Question on envelope-carrier description of traveling wave

I'm doing a research internship in attosecond physics right now, and one of the really important things in the field is the description of a propagating laser pulse as the combination of a slowly (or ...
2
votes
0answers
24 views

What is the idea behind counting the number of excited states and the representation of a group ?

While reading Polchinski's Chapter 1, I encountered the following on page 24, "For example, the $(D-1)$ dimensional vector representation of $SO(D-1)$ breaks up into an invariant and a $(D-2)$-vector ...
1
vote
2answers
33 views

Can the magnetic fields of EM radiation be harnessed or measured?

We use the electric component of EM radiation to create the EM radiation and to detect it (antennas and Etc.), but does anyone know of a situation where the magnetic component of EM radiation is used? ...
1
vote
0answers
21 views

Active-sterile mixing for KeVins

People sometimes talk about KeV mass sterile neutrinos as a warm dark matter candidate. I think they call them KeVins (horrible name btw). Now, In order for it to be a good dark matter candidate it ...
1
vote
2answers
49 views

parity invariance of Einstein, Maxwell and Dirac Lagrangians

How can we show that Einstein, Maxwell and Dirac Lagrangians are parity invariant?
0
votes
1answer
29 views

Will an electron gun fire behind it?

If an electron travels as a wave, can it therefore not be aimed with any precision? If you fire an electron gun, can't you aim it at a particular slit? If the electron travels as a wave, will an ...
0
votes
2answers
50 views

Can a hydrogen atom sit still?

Can we take a single lone hydrogen atom (proton and electron?) and set it in one place and observe it staying there? How about just a proton? A neutron? How about just an electron?
0
votes
2answers
34 views

Deriving spring oscilation period

We have a spring attached to a wall and at the other part an object on a frictionless surface. I tried to calculate the spring oscilation period. I used the conservation of energy and kinematics ...
0
votes
1answer
11 views

Effect of crystal growth on its scintillation

How does crystal growth affect its scintillation properties? What are possible ways in which growth of CaWO crystals grown via Chochralski method could be modified to avoid non-linearity in its ...
1
vote
1answer
26 views

Historical analysis of light interference - difference frequencies

It is well-known that light of two different frequencies illuminating a detector will produce an output with a component at the difference frequency. While such considerations are eminently useful ...
-1
votes
0answers
33 views

Lack Of Definitions?

I am reading French and Taylor's Quantum Physics textbook, and I am having some difficulty parsing a few words. One such word is the gram-equivalent. The author's seem to never explicitly define ...
0
votes
1answer
19 views

Which function denotes the energy of thermal motion within a system?

In thermodynamics, the heat $Q$ is defined as a type of energy in transfer, and is not a state function, which function denotes the energy of thermal motion within a system?
-1
votes
0answers
21 views

heat supplied by two heat source in reversible heat engine [on hold]

A reversible engine is supplied with heat from two reservoirs at 900 K and 600 K and rejects heat to a sink at 300 K. The engine develops work equivalent to 90kJ/s and rejects heat at the rate of 56 ...
3
votes
0answers
34 views

Berry's phase: in which space does the degeneracy appear?

This question follows a previous one of mine: Adiabatic theorem and Berry phase. In his original paper [ M. V. Berry, Proc. R. Soc. Lond. A. Math. Phys. Sci. 392, 45 (1984) ], Berry discussed the ...
0
votes
1answer
19 views

measuring pressure drop of air flow over a pipe [on hold]

I am working on a project like fluid flow analysis(air flow), i have tried to calculated the pressure drop over the flow using u tube manometer , the pressure head ( the difference in manometer ) is ...
0
votes
0answers
17 views

Any help available for Solid State Electronic Devices and Materials? [migrated]

I am teaching and doing research work in Solid State Electronic Devices and Materials, which is a subset of Materials Science & Engineering - a branch of Applied Physics. I want to know if this ...
2
votes
1answer
34 views

In a radioactive Bose-Einstein condensate, would all the atoms disintegrate simultaneously?

They're all supposed to do the same thing - so I suppose they would? Also, would the resulting half-life be the same as that of the individual atoms it is made up of?
2
votes
1answer
28 views

How to calculate the drag coefficient using terminal velocity?

I was wondering if it were possible to calculate the drag coefficient by allowing an object to reach terminal velocity. Can you rearrange the terminal velocity formula to give the drag coefficient?
0
votes
1answer
32 views

Kinetic energy and potential energy variation over distance in SHM

When you compute the average potential energy of a horizontal spring mass system from the mean position to the positive amplitude A, the value comes out to be $\frac{1}{6}kA^2$. For the average ...
1
vote
0answers
25 views

What is it that makes an electron maintain a distance from the positively charged nucleus? [duplicate]

What is it that makes an electron maintain a distance from the positively charged nucleus? Why aren't electrons merely pulled into and absorbed by the nucleus ?
2
votes
2answers
85 views

Describing a circular current loop as delta function

It would be really nice to see how Jackson got eqn 5.33 on his example problem for finding the vector potential of a circular current loop $$ ...
3
votes
3answers
69 views

In scattering, how does a particle 'know' which direction it is being illuminated from?

In scattering experiments, for example light scattering, the scattering strength from different sized particles is depicted as below. What I can't understand is: how does a particle know which ...
1
vote
1answer
54 views

Distance and velocity question

I know that speed is the derivative of distance. So integrating speed should give you distance. Let's suppose we have a speed which obeys this function: $$ v(x) = 2^{2^x} $$ So at time 0 the speed ...
3
votes
2answers
81 views

How “unnatural” is the universe? [on hold]

Looking to read up on the impact the discovery of Higgs boson has on the String Theory I came upon these two paragraphs in an article about the Higgs boson Nobel Prize: One possibility has been ...
10
votes
4answers
2k views

How did they take photos of Jupiter?

How did they take photos of Jupiter - I mean Jupiter is illuminated and that's a lot of light to produce. Am I missing something, and there was some sort of dark photo technology used, or was there ...
3
votes
1answer
54 views

Cartesian Coordinates to Polar Coordinates

I apologize if this question is trivial, but I am new to physics and am struggling with some of the basic concepts. Working in $\mathbb{R}^2$ with standard coordinates $(x,y)$, suppose we have a ...
2
votes
1answer
61 views

Killing Equation, trouble with tensor algebra

I'm attempting to follow a proof that the commutator of two Killing vectors is itself a Killing vector. The source that I've posted is from my course notes. I've highlighted the part I'm stuck on. ...
1
vote
1answer
36 views

Woodwind instruments overtones [duplicate]

When playing woodwind instruments, e.g., flute, if one blows harder, the sound will be one octave higher. Even harder gives even higher overtones. Does anyone know why?

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