0
votes
0answers
2 views

Can someone explain the quote “there would be no chemistry if electrons acted as bosons”?

I am reading a book and in a quote it says that if electrons acted as bosons, then all the electrons would occupy the lowest energy state, and there would be no chemistry. What does the author mean ...
5
votes
1answer
16 views

How does the sun's surface conduct thermal energy from the convective zone to the corona?

How does the surface of the photosphere conduct thermal energy from the convective zone to the corona, while remaining at such a relatively low temperature itself? It seems odd to me that the ...
0
votes
1answer
16 views

Perpendicular doppler effect photons

If I have a photon with frequency f in the lab frame and the observe it in a inertial frame moving perpendicular to the photon. The direction of the velocity of the photon must change but does this ...
0
votes
0answers
21 views

Path integral measure fourier transform

Let's have $$ Z[J] = \int D \varphi e^{iS[\varphi , J]}, $$ where $\varphi$ denotes real scalar field. Let's make Fourier transform, $$ \varphi (x) = \int e^{iqx}\varphi (q), \quad \varphi^{*} (q) = ...
0
votes
1answer
16 views

SU(3) singlets and triplets

I was reading my prof's notes and came across a passage that I didn't understand: Consider a chiral SU(3) symmetry, under which the left-handed parts of the spin-1/2 fields of a fermion-number- ...
0
votes
0answers
9 views

Entanglement of two particles with same values of the entangled parameters?

The question For an entangled state consisting of systems A and B, if A is measured when does the wavefunction at B collapse? contains next entangled state: If there are two systems A and B, with ...
2
votes
3answers
62 views

Is it possible to generate energy by the moon orbit?

My question could be a little bit surreal, but I was thinking about this: A hydroeletric plant transform the energy from the water passing through the turbines into electricity. Correct? If the ...
2
votes
1answer
47 views

Massless particle that have momentum not equal to 0

I saw some problems in special relativity that use conservation of total energy and momentum and the conclusions are spectacular. My problem is the following: how can a massless particle like neutrino ...
0
votes
0answers
20 views

Angular momentum wavefunctions with respect to different axes

I've been learning about quantum angular momentum, and I have a question about the relationship between quantum mechanical angular momentum wavefunctions with respect to different axes. I know that ...
2
votes
3answers
37 views

Does my (too low) tire pressure, affect the speedometer of my car?

Does my (too low) tire pressure, affect the speedometer of my car? How big is this effect?
1
vote
1answer
31 views

Units of eigenvectors

Consider for example a mass matrix $M$, $\lambda$ one eigenvalue and $X$ a corresponding eigenvector. Then $[M]=\text{mass}$ (the brackets indicate the "unit operator"), and $MX=\lambda X$ so ...
4
votes
3answers
72 views

Can we find the exponential radioactive decay formula from first principles?

Can we find the exponential radioactive decay formula from first principles? It's always presented as an empirical result, rather than one you can get from first principles. I've looked around on the ...
1
vote
1answer
21 views

Explanation of different magnetic field measurements due to frame of reference

If there is an stationary infinitely long wire carrying current I, and we turn on a gaussmeter, it will record a magnetic field B. Since I know the Biot-Savart law, I am satisfied with this ...
0
votes
0answers
14 views

Nuclear medical physics [on hold]

How do you calculate the half life of daughter isotope (in secular equilibrium) Given a table of countrate(cps) and time (min). Like: Time (minutes) Count Rate (cps) time (min) Count Rate ...
0
votes
0answers
12 views

Electric field/ Gauss´s Law [on hold]

if I want to calculate the electric field, since I have 3 charged densities. The first one is -2 microC/m^2 , the second one is +4 microC/m^2 and the third one is -5 microC/m^2. What would be the ...
1
vote
1answer
33 views

Are energy and momentum separable for EM waves

Everywhere I get to read statements like EM radiations and EM fields carry "energy as well as momentum " . I wonder if energy and momentum are inalienable . Is it possible for a field to carry only ...
-2
votes
0answers
12 views

Draw a circuit for simulating the solution of this equation [on hold]

Using an opamp, how can I draw a circuit for simulating the solution of this equation : 3(dy/dx)+5x=0
0
votes
0answers
15 views

Why IR divergences cancel by cross sections of next-to-leading diagrams?

I was reading QFT & Standard Model by Schwartz, Chapter 20 which is about IR divergences. He says that IR divergences only cancel cross sections for processes involving different initial or ...
0
votes
0answers
16 views

How can we determine the Hypercharges in a GUT like SO(10)?

I understand how the assignment works for a symmetry breaking like $$SO(10) \rightarrow SU(3)_C \times SU(2)_L \times SU(2)_R \times U(1)_X$$ The Hypercharge can then easily computed by $$ ...
-5
votes
0answers
24 views

Electric circuit question [on hold]

A 100W bulb is connected in series with a room heater.If now 100W bulb is replaced by a 40W bulb,the heater output will (Decrease) (Increase) (remain same)? And explain why?
0
votes
0answers
16 views

Magnetic levitation manipulation

Suppose a small crystal or mineral piece with a completely known structure was held by magnetic levitation. Would it be possible to orientate the piece by manipulating the magnetic field so that a ...
0
votes
1answer
17 views

Can a particle accelerator really be constructed which can actually change the properties of a material (create a new kind of atom)?

Can a particle accelerator really be constructed which can actually change the properties of a material (create a new kind of atom)? If not, what are some ways to create or synthesize a new atomic ...
3
votes
1answer
31 views

Does Fermat's principle of least time apply to sound waves?

I am reading Feynman's presentation of Fermat's Principle of Least Time, which explains the behavior of light; does it apply to waves in general? for example sound waves or waves on the surface of ...
0
votes
0answers
5 views

What is meant by the (aperture size) of optical deflectors in laser scanners?

How do you measure the aperture size in a laser scanner.
-2
votes
1answer
70 views

What happens in a universe with only two electrons?

What happens in a universe with only two electrons? Do they stay as waves or do they collapse into particles?
1
vote
1answer
32 views

How do we measure distance using parallax?

This is a quick mock-up of how stars are measured using parallax method. My question is : How on earth (literally) do we measure the anfle $\theta$? Is theta measured from the zenith of Earth? ...
-2
votes
1answer
36 views

Space Contraction [duplicate]

Is there any experimental evidence of space contraction which theory of spacial relativity predicts? You should bear in mind that GPS & muon detection beyond the distance permitted by its half ...
0
votes
0answers
12 views

For an entangled state consisting of systems A and B, if A is measured when does the wavefunction at B collapse? [duplicate]

If there are two systems A and B, with an entangled state consisting of $$\mid \psi \rangle = \frac{1}{\sqrt{2}} (\mid \uparrow _A \rangle \,\, \otimes \mid \uparrow _{B} \rangle \,+ \mid \downarrow ...
0
votes
1answer
7 views

What is the potential associated to a pure torque proportional to one of the principal axis of a particle?

I'm writing a code in molecular dynamics in which a particle is subject to a pure torque around one of its principal axis. E.g., if the particle has principle axis $\hat u$, $\hat v$, $\hat f$, all ...
0
votes
1answer
69 views

Commutator and Hamiltonian

Assume that $[\hat{A},\hat{H}]_-=0$ and $[\hat{B},\hat{H}]_-=0$ but we know that $[\hat{A},\hat{B}]_-\neq0$. Then the stationary states of $H$ are degenerate. How to prove it?
0
votes
0answers
7 views

How much charge per unit time passes with the Josephson current

I wonder how does the simple defintion of a current $I = \frac{dQ}{dt}$, i.e. charge per unit time which passes through some area, is applied to the Josephson effect. If I have a Josephson junction ...
-4
votes
0answers
49 views

If one were to have boots made of Vibranium, could one jump from any height? [on hold]

Vibranium is a fictional metal from the Marvel universe, with interesting properties, it "possesses the ability to absorb all vibrations in the vicinity as well as kinetic energy directed at it." It ...
2
votes
3answers
133 views

Where does air pressure come from?

Where does air pressure come from? I thought it was from gravity or the speed of the gas resulting from its heat. However, analyzing my own hypotheses, I think that my 'heat conjecture' is probably ...
8
votes
4answers
799 views

Paradox in applying Newton's second law [duplicate]

Suppose I apply two vertical but opposite forces with the same magnitude in a body like is shown in the picture: According to newton's second law, the center of mass shouldn't accelerate, since the ...
0
votes
2answers
33 views

Derivation of plane wave from inner product of position ket and momentum ket

In textbooks it seems to be taken for granted that $$\langle \mathbf{r}|\mathbf{k}\rangle = \frac{1}{\sqrt{\Omega}}\exp(i\mathbf{k}\cdot\mathbf{r}).$$ I'm sure it's obvious but is there a ...
0
votes
1answer
20 views

Continuity equation for charge and current densities of an accelerated point charge

For a point charge that moves with the trajectory $ \vec r(t)$, we know that it has the singular charge and current densities $$ \rho (\vec x, t) = q \delta^3(\vec x - \vec r(t)) $$ $$ \vec J(\vec x, ...
0
votes
2answers
36 views

Understanding notation regarding particles states and wavefunctions

In the development in my notes of second quantisation I have a problem in understanding notation. We start by considering a basis $\psi_i(\mathbf{r})$ for the Hilbert space of single particle ...
3
votes
1answer
27 views

Do two bodies spinning about the same axis in the opposite direction repel each other?

I recently read about the GEM equations, which look very much like the Maxwell's equations. Does this mean the behavior of mass is like the the behavior of the electric charge? So for example if you ...
0
votes
3answers
27 views

Database of experimental cross sections for atomic collisions

Does the atomic-physics community keep a comprehensive database of experimental data (cross sections) for atomic collisions? I am looking for data about Bremsstrahlung, ionization, elastic and ...
0
votes
0answers
7 views

What technologies exists today that can reduce the effects of air pollution on individuals (eg. carbon capture)? [on hold]

I'm researching the matter of air pollution and I would like to know if there are any technologies that I might not be aware of (beside carbon capture and Sharps's plasma cluster) whose objective is ...
1
vote
1answer
29 views

What are some current models for neutron star core?

How are neutron star cores described today, do we use models of superfluidity/superconductivity for instance?
9
votes
1answer
2k views

Is an H bomb a better “fusion reactor” than the Sun's core?

A few days ago I asked about a fusion reactor design I was thinking about and got a well-founded answer by #BowlOfRed#. There is the question I posted: Another cold-fusion reactor scheme :) Is it ...
1
vote
1answer
26 views

What is the importance of reciprocal lattice?

Reciprocal lattice is the diffraction plot of a crystal. Now with the STM instrument we can get the get the topology of the crystal, so what is the importance of reciprocal lattice or the Brillouin ...
0
votes
1answer
36 views

Determining the path of a light ray

Let's consider a ray in the plane $xy$. Let the refractive index be defined in any point of the plane with the function $n(x,y)$. In time $t=0$ the ray is located in coordinates $(x_0, y_0)$ and its ...
2
votes
1answer
38 views

Could you make a system that exchanges matter but no thermodynamic energy?

Normally we distinguish between open, closed and isolated systems, assuming that the 4th possibility does not exist, as an exchange of matter presupposes energy exchange. Could it be nevertheless ...
0
votes
0answers
23 views

value of $n$ in modified gravity model

In the modified gravitational model $ f(R)=R+\lambda{R_{0}}\left(\left(1+\frac{R^{2}}{R_{0}^{2}}\right)^{-n}-1\right) $ Are there any restrictions on the value on $n$. Also is this model valid for ...
0
votes
0answers
14 views

Is the induced EMF dependent on the conventional or actual flow of electrons?

I have been studying Faraday's Law and Lenz's Law and the flow of current to oppose change in flux linkage. My question is whether the actual flow of electrons to the top of a material makes the EMF ...
1
vote
1answer
38 views

How can we see the electrons?

As you can see the blue glows is the electrons flowing inside the cathode ray tube under vacuum condition. My question is how can we see the electrons in the setup? electrons are everywhere but why ...
3
votes
1answer
418 views

why cant we use a pair of polarizer ( whose pass axis are oriented at 90 degrees ) to protect from entry of harmful radiation?

If a pair of polarizers can block EM waves passing through it, then can we use them for protecting against harmful radiation (in nuclear reactors and also in spaceships) in thermo flasks to ...
0
votes
1answer
18 views

Energy, Voltage Drop, and Current

In an electrical circuit consisting of just a source and some load, when current hits the load, the voltage drops. This means that the potential energy of the charge drops. If the potential energy ...

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