-1
votes
1answer
12 views

On Elementary Particles

The mass of positron and electron are same.Also their charges are equal in magnitude but opposite in nature.Then why positron is not called one of the elementary particles? Is this only because it was ...
0
votes
0answers
5 views

How to increase flow?

I am coming up with ideas of how to increase grain (corn, soybeans etc,) flow in a tube. My first idea is to have spiral ribs inside of the tube to create a vortex effect that will allow the grain to ...
0
votes
1answer
14 views

Phenomena in the intersection of general relativity and quantum mechanics

I am looking for physical phenomena that have aspects involving both general relativity and quantum mechanics. The only example I know is Hawking radiation. While black holes have large gravitational ...
0
votes
0answers
10 views

Are there any good books about GUTs?

I'm starting to get a little desperate, because I can't find a good, introductory treatment of Grand Unified Theories. So far the only books I found are Mohapatra Unification and Supersymmetry Ross ...
0
votes
2answers
10 views

What the wave function looks of a particle in the infinite square well looks like after collapse for measurements of position and energy

Consider a particle in a the infinite square well from x=0 to x=L. At t=to, I make a measurement of position and get x=L/2. What is the resulting wave function at t=to? My understanding, from reading, ...
0
votes
0answers
6 views

Derivation of Jefimenko's Equation in Jackson's EMT book

I have been trying to understand the derivation of Jefimenko's equation in Jackson on p.246-247 which can be seen in the photographs attached. First of all I did not fully comprehend the ...
0
votes
2answers
13 views

How to calculate temperature of an incandescent bulb filament?

Suppose we have a light bulb, for which we know its power rating, like voltage of $12\mathrm V$, and power consumption of $10\mathrm W$. We also know it's a halogen bulb with a tungsten filament ...
-1
votes
0answers
11 views

Compute the temperature of the reservoirs between which the engine operates

An ideal gas for which $c_v$ = 3R/2 is the working substance of a Carnot engine. During the isothermal expansion the volume doubles. The ratio of the final volume to the initial volume in the ...
1
vote
1answer
24 views

How to derive $r, \theta, \phi$ for the sperical coordinate gradient?

I'm trying to figure out how to get the gradient in spherical coordinates. I'm as far as the author writes in this answer: http://physics.stackexchange.com/a/78514 and I understand how and why to get ...
0
votes
2answers
22 views

Expanding universe - does the Hubble red shift come from gravity?

Measurement of the expansion of the universe is based, in part, on the red shift of light. The speed of light is a constant, although some people argue that it may be changing over time, I am going to ...
0
votes
0answers
9 views

plasma and infinite acceleration

I am trying to set up a simulation of particles (they are not any particular kinds of particles, they are just points that repel each other). All the particles repel each other through the inverse ...
0
votes
0answers
19 views

Total Energy of Inverted Pendulum

I have to find the total energy $V$ of an inverted pendulum (rod). The following parameters and their values are given: Mass $m$ and length $l$ of the pendulum $\theta$ as the angle of the ...
0
votes
0answers
21 views

Physical interpretation of legendre transformations in thermodynamics

I have found this question(Physical meaning of Legendre transformation) and I have some questions regarding the transformations in thermodynamics, In thermodynamics we have: $$H= U+PV $$ $$F=U-TS ...
0
votes
0answers
28 views

The structure of spacetime and entanglement [on hold]

how many ways to quantize gravity? Do they contradict each other? How to apply long-range entangment/Professor Wen Xiaogang's theory to virtual pairs
0
votes
1answer
23 views

“Definition” of internal energy

Conversation of energy implies that if we have a thermally insulated system which goes from state 1 to state 2: $$\Delta E_{12}=E(2)-E(1)=\Delta W_{12}$$ and the 1st law of thermodynamics ...
0
votes
3answers
32 views

How does $p=fv$ hold when $v=0$ and an engine is working?

Standard high school equations: Work = Force x Distance Power = Work / Time = Force x Distance / Time = Force x Velocity When a space rocket takes ...
-3
votes
0answers
20 views

What would happen if a space ship may travel as quickly as the speed of light? [on hold]

Ofcouse, it is impossible. Beacuse of need of infinite energy to accelarate infinite mass... Bur if it might be possible...??? I did a fictional study as an amateur. I shared it, but i need feedback ...
-2
votes
0answers
9 views

Calculate bicycle efficiency power transmission?

How can I calculate the efficiency of power transmission from a person to a bicycle with standard flat pedals? How can I calculate the efficiency of power transmission from a person to a bicycle with ...
0
votes
0answers
18 views

Another universe in the other side of a black hole? [duplicate]

A common notion is that there is another universe in the other side of a black hole, past the singularity point....is this true? does it have any scientific support?
1
vote
1answer
36 views

Can a hypothetical universe have more than 2 types of its dimensions?

Our universe is often described as having 3 space-like dimensions and 1 time-like dimension. Can hypothetical universe exist with more than space and time like dimensions? If so how would these ...
-2
votes
0answers
11 views
-3
votes
0answers
14 views

How would I prove the gamma normalization relation without Clifford Algebra? [duplicate]

The equation in question is $$ \left ( \gamma ^{\mu } \right )^{\dagger }=\gamma ^{0}\gamma ^{\mu }\gamma ^{0}$$
4
votes
1answer
39 views

Speed of gravity within a mass

We all consider that gravity travels at the speed of light. Light travels at the speed of light except when it is in a medium ,say glass, where it travels slower. What happens when gravity passes ...
0
votes
1answer
20 views

Aharonov-Bohm experiment: A possible way to understand potentials?

I'm posting this question as a function of an another question I found here: What is potential energy truly? The answer of WetSavannaAnimal aka Rod Vance. As I understand the hole point is to see ...
-1
votes
0answers
15 views

XRD of Graphene Foam

At what 2$\theta$ values Graphene Foam shows the peaks in XRD ? I got two peaks at 2$\theta$ values 14.7 degree and 17.2 degree..
-2
votes
0answers
19 views

Solving IVP $\frac{dE}{dx}= -\gamma\frac{dx}{dt}-\alpha$ [on hold]

I need to solve the differential equation $$\frac{dE}{dx}= -\gamma\frac{dx}{dt}-\alpha$$ with the initial value $$v(t=0)=v_O$$ I tried writing everything in terms of $v$ which gives me: ...
0
votes
3answers
39 views

In aircraft design why are light materials preferred to heavy ones?

Especially given the relative cost between (say) steel and carbon composites. After all, I assume most fuel is consumed overcoming drag not accelerating mass. Once an aircraft reaches cruising speed ...
1
vote
0answers
8 views

Wave velocity (R)LC circuits.

I'm attempting to simulate some fluid like mechanics using circuits. Specifically wave propagation. I am attempting to measure the wave propagation velocity using an oscilloscope on the circuit below, ...
-1
votes
3answers
54 views

What logical/mathematical proof do we have to show that, everything which is called electron are identically the same?

Premise 1: Physics don't believe in sense "organs" of the human "robot" (more commonly said "common sense deceives us"). Premise 2: Physics believes in logic or mathematics. Background thrust: ...
0
votes
1answer
37 views

Quantum state of a system after measurements with non-commutative operators

a) Assume two operators $A$ and $B$. 1) Assume $$[A,B]=0 $$ and $$ ψ= \sum c_n u_n ~~~~\text a~ wavefunction~ describing~ the~ state~ of~ the~ system $$ with $$Aψ=a_n u_n $$ $$Bψ=b_n u_n$$ If we ...
0
votes
1answer
14 views

Approximating energy loss caused by drag force

We know the usual aerodynamic drag equation is given by: $$F_d = -bv^2$$ Where $b$ here is just some constants combination related to the property of the fluid and the material passing through. My ...
1
vote
1answer
23 views

Digital colors: why RGB instead of RYG?

We know that Red, Yellow, Blue are primary colors. Any other color can be created by mixing these color. Graphical representation is below: But when I began to learn about computers, I noticed that ...
-1
votes
0answers
14 views

Clocks in moving inertial frames

A clock $C$ is at rest at the spatial origin of an inertial frame $S$. A second clock $C'$ is at rest at the spatial origin of an inertial frame $S'$ moving with constant speed $u$ relative to $S$. ...
-1
votes
0answers
28 views

Sinusoidal Wave Problem

A sinusoidal wave of frequency $650 \mathrm{Hz}$ has a velocity of $450 \frac{\mathrm{m}}{\mathrm{s}}$. Determine the distance between two points on the wave that differ in phase by 1.5 ...
-3
votes
1answer
37 views

In Gauss's law, why do we use an infinte long wire or long plane to calculate electric field intensity?

In the NCERT textbook of class 12, in the section on applications of Gauss's law, there are three applications. The first application is to calculate the electric field intensity around an infinitely ...
2
votes
0answers
17 views

Single particle passing through the double slit at a time

In modern experiments, With the classical setup of photons or electrons passing through double slit, the intensity is kept extremely low, such that one can detect a single particle passing through ...
3
votes
2answers
118 views

How to interpret single photon interference when the two possible paths are different in length?

Here is my question. I struggle with the definition of single photon interference. Let’s assume we have a Michelson interferometer and the interference pattern we observe is a single photon result, ...
1
vote
0answers
25 views

Birkhoff Theorem proof reference [on hold]

I am looking for a reference with a clear (and easy to understand) proof of Birkhoff's theorem in general relativity.
2
votes
1answer
24 views

How does the second law of thermodynamics affect the efficiency heat-to-work conversion, at the molecular level?

I understand the second law of thermodynamics in terms of the improbability of the high--and-low-velocity particles of a gas to separate themselves so that at one moment they are at different sides of ...
3
votes
1answer
37 views

In an elastic collision, can we choose between cons. of energy and cons. of momentum?

Suppose we have two solid spheres with masses $m$ and $M$, respectively, and that $m$ is significantly smaller than $M$. The lighter sphere is placed directly on top of the heavier one, and the two ...
0
votes
0answers
42 views

how to define infinite/finite systems in nature?

Infinity may be fixed and limited in a set, sequence, or series to repeat the same things infinitely and the finite is not fixed/unlimited to repeat different things finitely. Both can be described by ...
0
votes
2answers
19 views

What is the formula of power of an optical instrument?

I have searched and found that the power of a lens, with surrounding medium of refractive index $n$, is $n/f$ where $f$ is the focal length, the formula is $$n/f=(n'-n)/R1 + (n-n')/R2.$$ But in my ...
0
votes
4answers
50 views

How is gravity proportional to space-time curvature in the rubber-sheet analogy?

In General Relativity, Einstein established that gravity is due to the curvature produced by objects in space. We all know that gravity is proportional to mass. The picture Einstein painted looks ...
-1
votes
0answers
25 views

Is it possible to cut the contents of an atom? (theoretical question)

For example, if I become the size of an atom and were to explore it. Then if I cut the proton, electron or neutron with a knife (remember, this is theoretical), what would happen? Would it blast, or ...
0
votes
1answer
31 views

Zero volume at zero Kelvin

Why does the volume of a gas become zero at 0 Kelvin? Can a Bose Einstein condensate be considered as matter? (I mean the volume becomes zero)
1
vote
0answers
21 views

Feshbach resonance in simple terms

I was reading up Feshbach resonances in cold atoms and I was unable to grasp the concept. I will tell you what I have understood. We consider two body scattering processes elastic as well as ...
-1
votes
1answer
19 views

Wave Equation - Vibrations & Waves

My question is basically how to do part ii) of this question even with the hint I am confused; the first part was simple; There's no dispersion & vp = vg = sqrt(hg) as required. But how would I ...
0
votes
0answers
21 views

Optics modelling software

I am looking for software that could allow me to model the internals of my spectrometer. I would imagine some sort of ray tracer that allows me to add mirrors, slits, gratings etc. This way, I can see ...
-4
votes
2answers
53 views

Is it possible to travel ONLY through Time and not Space?

The question is as stated above. I although think, the most probable answer is no, but I really want to know the reason to it. If, One can travel through only space by travelling at the speed of ...
-1
votes
1answer
22 views

Which of the Physics textbooks would you recommend I read this quarter (Analytical Mechanics)? [duplicate]

My Analytical Mechanics class this quarter has one required textbook: "Classical Dynamics of Particles and Systems" by Thornton & Marion and three recommended readings: "Mechanics" by Landau ...

15 30 50 per page