0
votes
0answers
8 views

“If the astronaut found that light slowed down relative to his motion, he would have detected the very ether wind that Michelson failed to detect”?

The following extract is from Relativity Simply Explained by Martin Gardner (Amazon link): Consider an astronaut in a spaceship that is racing alongside a light beam. The ship is traveling with ...
0
votes
0answers
5 views

Lorentz invariant phase space of a three-body decay process

I am not following the use of delta function in the 3-body decay process. In $\gamma^* \to gq\bar{q}$ process, with $\gamma^*$ being a virtual photon, we have a phase space factor $d^9R_3 = ...
-1
votes
1answer
14 views

Intitutive meaning the unit of Force N

I infer 1 Newton of force = 1 kg.m/ sec squared means a force if acting continuosly on a body at rest would make it gain an acceleration of 1 m/sec squared each second.So the change in velocity is 1-0 ...
0
votes
0answers
7 views

Probability density function as number of particles per unit volume?

In this book Quantum Mechanics by P.J.E. Peebles pg 365 it hints at the idea of the wave function been the probability of finding $n$ particles per unit volume. I have looked in other books and on ...
1
vote
1answer
13 views

Solving the Klein-Gordon equation via Fourier transform

I have been writing a personal set of notes on QFT and I'm currently writing up a section on solving the Klein-Gordon (K-G) equation. I many texts that I've read, the author starts by expressing the ...
0
votes
0answers
9 views

how tough is research work? [on hold]

I am going to be a university graduate with good C GPA but still I am worried that whether I can do M Phil or not? I want to ask is it difficult to do research and get your work published in a ...
1
vote
1answer
7 views

Is the mass of the Z due to mixing with the photon “precursor” B or to interaction with the Higgs?

I want to get something clear that I do not seem to understand. I used to read that the photon A and the Z boson are (different) linear combinations between the W^0 (neutral weak boson before SU(2) ...
0
votes
1answer
22 views

Can the uncertainty principle be redefined for different standard deviations?

$$\sigma_x \cdot \sigma_p \ge {{\hbar} \over {2}}$$ Where the $\sigma$ is the standard deviation. What happens to the inequality if you use a different definition of $\sigma$. For instance what ...
0
votes
1answer
15 views

Are measurements of time and distance independent or always coupled by the speed of light

In texts about special relativity the light clock is usually described as a tool to measure time $t$. It counts how often light travels along a given distance $d$, i.e. $t = d/c$, where $c$ is the ...
0
votes
2answers
29 views

Is causality a necessary and sufficient condition for special relativity?

Is there a way to "build" special relativity by using causality as one of the axioms? Or is it just a consequence of a fact that the speed of light is same in all reference frames?
0
votes
1answer
28 views

Why can the probability function for a particle in an infinite square well be larger than 1?

For a particle in a one dimensional infinite potential well of width $L$ the probability function is: $$P_n(x)=\left(\frac{2}{L}\right)\sin^2\left(\frac{n\pi x}{L}\right)$$ for $0\leq x\leq L$. The ...
2
votes
0answers
30 views

Square root of matrix appears in massive gravity. How to calculate the square root of matrix $A+B$ perturbatively?

$A=\text{diag}\{\lambda_1,...,\lambda_n\}$, where $\lambda_i$ can be any number and not necessarily a small number, $\lambda_i>0$, $B$ is a positive definite symmetric matrix, and ...
-2
votes
1answer
26 views

What are mesons and leptons?

What are mesons and leptons? I get decay processes where the decay products are leptons (electrons, positrons, neutrinos, mesons etc.). What are these?
0
votes
0answers
14 views

What makes electrons behave like particles or waves at different times? [duplicate]

I am quite puzzled about the theory that electrons or light often behave as particles and sometimes as waves. So, I wanted to know more about this phenomena and what happens when and why.
-1
votes
0answers
15 views

Vertical throwing exercise [on hold]

I'm struggling with this question Assume an object is resting on the ground, in $t=0$ there is a force that starting to work on it, which grants him vertical acceleration towards up, $a=3m/s^2$, ...
0
votes
1answer
21 views

Why is hydrogen, nitrogen, carbon and oxygen the most common constituents of interstellar molecules?

Could someone elaborate more on the use of the word "constituent"? Is the question basically asking why these four elements are the most prevalent in interstellar molecules? If so, why are they the ...
-1
votes
0answers
14 views

Derivative of effective action with respect to classical fields

I have some trouble with the effective action involving fermions. Consider the following effective action (QED): $$\varGamma = \int \mathrm{d}^4 x \left( j_\mu \mathcal{A}_\mu + \bar{\varPsi} \eta + ...
-5
votes
1answer
25 views

would a clock at Absolute zero have no mass

since Absolute zero corresponds to the theoretical state in which particles have no energy at all. and m = E/c^2 Then would an unwound clock have zero mass if it was cooled ,theoretically , to ...
0
votes
0answers
5 views

Estimate Uncertainties in Rietveld Refinement

I have the output of an x-ray diffraction experiment made on a thin film. Here I report the output of the experiment (I analyzed those data using powdercell and coloured regions have been excluded ...
0
votes
1answer
24 views

Is harmonic oscillator continuous variable system?

In the literature I have seen that the notions "our system is continuous variable system", "Hilbert space of our system is infinite" were used as if they were equivalent. For example for harmonic ...
0
votes
2answers
13 views

Nucleus validation

Inside the nucleus of an atom is the Coulomb's law valid? I mean that between proton, neutron and other elementary particles, i.e., meson etc. What will be the limit or validity of charges between ...
0
votes
0answers
9 views

Spin-orbit coupling of low band gap vs large band gap semiconductors

Why do low band gap material III-V semiconductors, like InAs, show a spin orbit coupling effect higher than large band gap semiconductors? Please give me some references if possible.
0
votes
1answer
33 views

A pendulum clock vs. an atomic clock

A pendulum clock ticks slower on top of a mountain and ticks faster at ground level, but an atomic clock ticks faster on top of a mountain and ticks slower at ground level. Gravity affects pendulum ...
1
vote
0answers
22 views

How is translational symmetry related to Fourier decomposition?

The book (The Cosmic Microwave Background By Ruth Durrer) about cosmological perturbations says that because of translational symmetry of the background at a constant time, we can decompose our ...
0
votes
0answers
18 views

Dmitri Mendeleev's Periodic Table [on hold]

Dmitri Mendeleev arranged his first periodic table according to the number of protons and valency electrons. How did he, and others of his age, know of these subatomic particles and electron shell ...
-2
votes
0answers
13 views

Electric Circuits HAVE to be closed? [on hold]

If there's Nothing happening between the positive and negative terminal of a battery, can they be split to create a line circuit?
-1
votes
3answers
30 views

Formula or relation for forcing spring movement over a certain time (as the image shows) [on hold]

i have explained my objectives in the image the fact is i'm planning to use such motion in programming but i have some serious trouble over controling the time that this motion finishes! what i'm ...
-2
votes
0answers
19 views

A problem from the Rudolf Ortvay Competition in Physics [on hold]

PROBLEM STATEMENT: A uniform circular disc is kept face down on a table which has a uniform friction coefficient.It is pushed in such a way that there is translational as well as rotational motion of ...
0
votes
0answers
11 views

Correlator $bc$ system

I have da doubt with bc system. Polchinski says (2.5.10) $$ b(z)b(0)~=~O(z). \tag{2.5.10} $$ I tried to compute the correlation function With eom, using eq (2.5.6b) by Polchinki, removing the ...
1
vote
1answer
17 views

Complex scalar theory: annihilation and creation operators give wrong commutators with Hamiltonian

The theory of a real (hermitian) scalar field can be found in many books and everywhere online. On the other hand, if we take the field non-hermitian, then I can only find notes on path integrals. I ...
0
votes
0answers
35 views

Why is it easier to calculate $\langle \chi|j\rangle\langle j|A| i\rangle\langle i| \phi\rangle$ than $\langle \chi|A|\phi\rangle$?

I was reading Feynman lectures III's Spin One; there at the machinery of quantum mechanics he discusses a situation in which he needs to find the amplitude of finding the particle at ${\chi}$ state ...
2
votes
1answer
30 views

induction of van der Waals forces

Is there a way to maximize van der Waals forces between two materials, by electrifying one material, thus creating dipoles/instantaneous dipoles and thus creating stronger van der Waals forces? has ...
0
votes
1answer
50 views

Can forces in N be thought of as a length?

A solid uniform 45.0 kg ball of diameter 32.0 cm is supported against a vertical friction-less wall using a thin 30 cm wire of negligible mass. (a)make a free body diagram for the ball and use it to ...
-1
votes
0answers
21 views

Graviton saturation, alternative explanation of galaxy rotation curves?

Is there any hypothesis that suggests that some kind of "graviton saturation" could be happening, explaining the weird rotational curves of galaxies, just like the concept of dark matter tries to do? ...
2
votes
0answers
15 views

Connection between the M5 brane and (2, 0) superconformal field theory

I have read that the worldvolume theory of the M5 brane is a $(2, 0)$ superconformal field theory (SCFT). But I have also learnt from talks that the $(2, 0)$ theory lacks a Lagrangian description. ...
0
votes
0answers
16 views

Jaumann deviatoric stress rate.

Background about terms in this question: Hookes law and objective stress rates From my understading, the Jaumann rate of deviatoric stress is written as: $dS/dt = \overset{\bigtriangleup}{{S}} = ...
1
vote
1answer
39 views

Polchinski Equation (10.4.7)

I'm having a problem to interpret eq. (10.4.7) in Polchinski: $$ \gamma(z)\delta(\gamma(0)) = O(z), \qquad \beta(z)\delta(\gamma(0)) = O(z^{-1}). $$ What does he mean by $\delta$? He tries to ...
1
vote
1answer
23 views

Why can touching an iPod charger sometimes cause one's skin to tingle?

I was visiting Shanghai recently. One afternoon, while sitting on the sofa, I inadvertently brushed a family member's arm. To my surprise, I felt an unnatural tingling from his skin—quite like a mild ...
0
votes
0answers
13 views

system to reposition a car

I was thinking of a system that will use ejected gas/liquid to reposition the position of a car and/or assist in braking. Would such system be viable? What parameters would such system have? Ie. to ...
0
votes
1answer
17 views

Ammonia Unloading

The Ammonia Unloading via Ships happens at -33degC, why the temperature don't drop off or increase during unloading or during high heat summers environment? What's make him to maintain the ...
-2
votes
0answers
21 views

Finding root mean square speed of an ideal gas [on hold]

Again a question ive never seen in my life... The molecules of an ideal gas have a root mean square speed of 520 meters per second at a temperature of 27 degrees celcius. Calculate the r.m.s speed ...
0
votes
0answers
16 views

Scalar gravity coupled to matter

I am reading Ortin's Gravity and Strings and trying to understand the generalisation of Newtonian Gravity to a relativistic field theory. On page 47 (link above) he motivates the study of the Poisson ...
2
votes
1answer
43 views

How can I add dark matter to my N body simulation?

I've written a simple non-scientific N-body simulation for fun: http://magwo.github.io/fullofstars/ I expected to create something looking like spinning galaxies (there are two invisible very heavy ...
0
votes
0answers
12 views

What is the free energy of an ideal chain under stress?

this question is related to potential energy of a segment of an ideal chain under external force. I calculated the canonical partition function for an ideal chain ($i$ stands for a single segment ...
0
votes
1answer
26 views

Quantum gravity- Vacuum catastrophe

Why does the predicted mass of the quantum vacuum have a very little effect on the expansion of the universe?
5
votes
0answers
27 views

Numerical Solution of the Convection Dispersion equation

I have asked this question on Computational Science and also on Mathoverflow, but no satisfactory answers so far. I thought maybe the physics community could shed some insight on the issue. I am ...
-5
votes
0answers
27 views

are you forgetting something? [on hold]

ok so you have said that it works by heating up the air around it and that if the surface is shiny that it will reflect some of the laser. but what about the color spectrum. as it is known if you ...
0
votes
0answers
12 views

To change the path of an electron beam travelling horizontally using a uniform electric field [on hold]

Problem: A beam of 20kV electrons is travelling horizontally. If one was to bend the path to make them travel vertically at the same speed, using a region with a uniform electric field, what are the ...
2
votes
2answers
33 views

What sources of magnetic fields in urban society are strong enough to lure a compass off north?

I'm writing about the usage of magnetometers in navigation applications. As part of my reasoning about why you should be careful with it's usage (I've shown in experiments that some environments bring ...
-2
votes
0answers
16 views

Earth shrinks to a small ball without the space between electron and proton [on hold]

If the space between electron and proton diminishes, our planet will shrink to a ball with radius 60 meters. This is a scientific fact, no need to debate on it. Then, all the materials are fantasy, ...

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