0
votes
1answer
25 views

Can condensation occur in a unsaturated vapor?

Consider that a gas mixture of vapor$+$inert gas is unsaturated with concentration (or molar fraction) $x_\infty$ far from a clear, cooled substrate of temperature $T_\text{w}$, i.e. ...
0
votes
0answers
25 views

Is the visible light from “red-hot glass” at least close to Blackbody Radiation?

In this really nice answer @RobJeffries explains the difference between the ideas of Thermal Radiation and Blackbody Radiation in the context of a source which may be in thermal equilibrium, but who's ...
0
votes
1answer
19 views

How can excite a semiconductor to make a photon just by heat in room temperature?

I want to know if a semiconductor in room temperature can excite by heat, producing photon, without any other source of energy?
-1
votes
2answers
54 views

What factors will make Earth re-rotate again if it stopped? [on hold]

"What will happen if Earth stopped rotating?" have been answered multiple times with a lot of informative and interesting answers. Continuing this hypothetical question, I have another one in mind. ...
0
votes
0answers
14 views

What is the Relationship Between Poisson Brackets and Additive Integrals of Motion?

Question in the title: what is the relationship, if any, between Poisson brackets and additive integrals of motion? Context: Is there anything we can say about additive integrals of motion in ...
0
votes
0answers
10 views

Slowly Varying Functions for Adiabatic Invariants - The Same as Karamata's?

In section 49 (and 50) of Landau and Lifschitz's "Classical Mechanics", adiabatic invariants are discussed, which are related to functions which vary adiabatically or "slowly" with time. Admittedly ...
0
votes
1answer
32 views

How does pressure change over time in an open box?

Imagine that you have a 1 cubic meter metal box with two 20 mm diameter holes. One of them is connected to an air-compressor that constantly pressurizes the inside of cube. Let's say 5 atm. The other ...
1
vote
0answers
24 views

Do gases have phonons?

A phonon is a quantized unit of sound; they are encountered when quantizing lattice vibrations in solids. Now, even an ideal gas supports sound waves, but in such a case, interactions between atoms ...
11
votes
3answers
1k views

Same photon or different photon?

Consider a typical optical focusing system: A small light source, then a collimating lens, then a focussing lens, and then a detector (e.g. CCD). Assume that source intensity is so low that only one ...
1
vote
0answers
22 views

What is a good mathematical introduction to QFT [duplicate]

I've noticed that, any time I try to pick up Peskin and Schroeder, the main stumbling block it the leap in mathematical constructs from QM. Is there a good textbook that could teach me some of the ...
2
votes
0answers
38 views

Gimbal Lock: why is it a problem?

I was watching this video http://www.youtube.com/watch?v=rrUCBOlJdt4 about the gimbal lock problem. I understood that during rotations it could happen that one DOF disappear. Looking at the middle ...
-1
votes
1answer
43 views

Why is standing still easier than walking?

Both the works basically push force into the ground.So why does walking require more work?
-1
votes
3answers
25 views

Frequency of other light in white light

I have this question in mind because I read that the frequency of light depends only on the source of light. If we consider a source of white light then it emits light of different colours also. Then ...
0
votes
0answers
16 views

Relativistic Mass and Potential Energy

In the chapter 16–4 of the Feynman Lectures, Feynman employs a thought experiment to explain why "if two particles come together and produce potential or any other form of energy; if the pieces are ...
0
votes
1answer
16 views

Counting states

Assume we have 6 particles, 3 with spin $\frac{1}{2}$ and another 3 with spin 1. The particles are distinguishable. The energy of a spin s is $\epsilon=-s \mu H$. How many energy states the system ...
0
votes
1answer
29 views

Do all solid objects emit visible light?

Are there solid objects that do not emit visible light? To my limited and humble knowledge, creating such an object would require us to "only" shift the spectrum of emitted radiation. Is it possible? ...
0
votes
0answers
14 views

Where is the zero electric potential energy point?

Does the point of the electric potential energy of zero is defined by human or dominated by the indefinite integral of the electric force?
0
votes
0answers
25 views

Double-slit intensity distribution for particles

For waves, the intensity pattern for the double-slit experiment is given by the following equation (as of David Morin's notes on waves) $$ I(x) = I(0) \frac{D}{\sqrt{x^{2} + D^{2}}}cos^{2} \left ( ...
-1
votes
1answer
29 views

Can tearing a piece of paper be chaotic?

When one thinks of chaos, then automatically the thought pops up that a very little difference in the initial conditions enlarges over time and you end up with a totally different end situation. When ...
0
votes
1answer
26 views

Which of the following bulbs will glow? [on hold]

When the switch is closed which of the following resistors are parallel. Here is my thought process. Consider the current flow from the voltage source. When the charges reach the junction where ...
0
votes
0answers
20 views

Applying AdS-CFT to traversable wormholes? [on hold]

ER=EPR recently brought up the connection between non-traversable wormholes and entanglements. What about traversable wormholes? Can we apply AdS/CFT to traversable wormholes?
0
votes
0answers
15 views

acceleration of water when it travels through garden hose

How to derive average acceleration of water as it travels through nozzle of garden hose. Suggest some assumptions for better understanding
7
votes
1answer
42 views

How can dimensional regularization “analytically continue” from a discrete set?

The procedure of dimensional regularization for UV-divergent integrals is generally described as first evaluating the integral in dimensions low enough for it to converge, then "analytically ...
1
vote
1answer
88 views

The mass of the proton times its charge radius is very close to 4ħ/c. Is this a coincidence?

The claim is $r_p m_p = 4 L_0 M_0 = 4\hbar/c$, where $r_p$ and $m_p$ are the proton's charge radius and mass, and $L_0$ and $M_0$ are the Planck length and mass. Using the muon measurement ...
0
votes
0answers
8 views

Momentum and laplacian in matrix geometry

In matrix geometry, one promotes the embedding coordinates $x^a$ of a geometry $\mathcal{M}$ to hermitian matrices $X^a$ of some rank in an appropiate manner. This we call the quantization of ...
1
vote
2answers
41 views

What does “transfer” of angular momentum mean?

The Moon’s gravity produces tidal deformations or “bulges” in the Earth. Because of the Earth’s rotation, the line that goes through the bulges is not aligned with the line between the Earth and the ...
0
votes
0answers
22 views

I need results or to conduct a simple experiment for a dynamics problem involving the range of a projectile launched from a pendulum

I have created a model to show how the maximum range of a projectile varies with respect to the velocity and angle of when the object is launched from a swing. I now need to compare these results ...
-2
votes
0answers
48 views

Does absolute motion exist?

Is it possible to determine if an object is in absolute motion by putting a (massless) accelerometer on it (from the moment it came into existence), and see if a flat line is recorded? An object is ...
-2
votes
1answer
31 views

In this energy conservation problem, why are the answers different with different units? [on hold]

Really basic question, but basically I'm given a change in height in centimeters (that's how I measured it). From that, I'm supposed to find the initial kinetic energy. $KE_i = PE_f$ After doing ...
0
votes
0answers
14 views

Finding the maximum possible uncertainty of an observable [on hold]

Show that the maximum possible uncertainty for any observable X is $\frac{1}{2}$$\|x_1 - x_2|$ where $x_1$ and $x_2$ are the extreme eigenvalues of X. (Maximize ($\sum_{i} p_ix_i^2 ) - (\sum_{i} p_i ...
2
votes
2answers
31 views

Pole and Barn Paradox w/ Spacetime Interval

I'm having trouble with a pole and barn paradox problem. The problem is as follows: A pole vaulter is running with a pole at $ v=\frac{\sqrt3}{2}c $. Her pole has a proper length of $L$. She runs ...
1
vote
0answers
11 views

Equivalent of the word “Attitude” for the other three DoFs [on hold]

When discussing the physical state of a thing (e.g. a satellite), you can refer to its attitude state (which, to me, consists of its attitude and its derivatives/rates) and its.... non-attitude state ...
1
vote
2answers
31 views

Finding the speed of electrons in a magnetic field

So I'm trying to solve this problem in which an electron beam is "drawing a picture" on a TV screen. The electrons are accelerated to a voltage of $3 kV$ by wire coils and are then directed to ...
0
votes
1answer
23 views

How does Modified Newtonian Dynamics (MOND) violate Newton's laws?

I have read some articles on MOND which indicate that a modification of gravity violate Newton's third law, but I don't know how exactly that works. I do know that if Newtonian acceleration is smaller ...
1
vote
1answer
12 views

How is it guaranteed that electrical connections could be made without destroying a diode laser?

A diode laser is a tiny diode and requires a microscope to see it. Since a laser generates a good amount of heat, the diode should be destroyed with the produced heat. But it does not happen. but why ...
0
votes
1answer
22 views

Electron velocity in hydrogen

I was speculating over the feasibility of myon catalysed fusion. Somehow I drifted away from that a little, and I was wondering if one can find a quantum-mechanical expression for the velocity of an ...
0
votes
1answer
58 views

Why is carbon not a semiconductor?

As opposed to silicon and germanium (or tin and lead), carbon is not a semiconductor --even though, they are in the same group. More interestingly, diamond (which is carbon) seems to be a good ...
5
votes
1answer
38 views

Understanding potential energy

I am self-studying the classical mechanics using the book by Taylor, and I have a question about the potential energy. The book (pg 111) says: If all forces on an object are conservative, we can ...
1
vote
1answer
33 views

Quantum teleportation and macroscopic objects

Purely speculative. If not allowed, I'll delete. If quantum teleportation was scalable to macroscopic objects, I assume it would require an amount of matter at the destination, equal to the amount of ...
1
vote
0answers
8 views

What wavelengths of electromagnetic radiation are emitted by the LH2/LOX reaction?

Rocket engines such as the Rocketdyne Rocket System 68 and the Space Shuttle Main Engine use liquid hydrogen and liquid oxygen as propellants. The exhaust from this type of engine is notable in ...
1
vote
1answer
23 views

Annihilation operator in harmonic oscillator

In Wikipedia's QHO page there is a moment when the following is stated: I don't know why "the ground state in the position representation is determined by $a|0\rangle=0$". I would say that the ...
0
votes
0answers
9 views

How to calculate heat emitted and the range

If I have a source of heat and I know it's surface temperature and size (suppose there are no barriers, only vacuum) can I then calculate the length to which the heat will be felt, and create a graph ...
1
vote
0answers
22 views

Conservation of Komar Mass

The definition of Komar Mass in GR is associated with one asymptotically flat end. However, a hypersurface may contain more than one end, such as the spacelike Einstein Rosen bridge in Kruskal ...
0
votes
0answers
23 views

Colliding beams vs static target

In this problem I need to find the threshold energy of a positron-electron collision that creates a Z boson (the reverse of the following picture; Z mass 92 GeV) in two distinct cases: collision ring ...
1
vote
0answers
18 views

Antiunitary operators in the tenfold way

In the classification of free fermion systems in condensed matter, physicists usually divide the systems into ten symmetry classes, first discovered by Altland and Zirnbauer. In their classification, ...
2
votes
3answers
41 views

Does visible light heat things up?

During a sunny day the walls of my house warm up (no surprise). My question: how much of this warming up (if any) comes from visible light? I associate infrared with thermal energy. If my house was ...
-4
votes
0answers
48 views

Where can a particle be found in a wavefunction [on hold]

Let me rephrase my question. Consider the 3d wave packet of a free particle moving along the x-axis. The wave packet will have components in the y and z dimensions as well as the x dimension. What ...
1
vote
1answer
33 views

Surface brightness

I have to compute the surface brightness as a function of the radius from the following set of data: {right ascension ($\alpha$), declination ($\delta$), magnitude (m)}. I also know the center of the ...
-4
votes
0answers
32 views

The Sun's space-time warp [on hold]

Can we infer that the skin of the Sun is (to some depth) blanketed by the space-time warp created by its own mass? Does the Earth's mass create any measure of a space-time warp?
0
votes
0answers
17 views

Charge Magnitude Based on Isoline Spacing

Suppose we have two positive charges of unknown magnitudes. We are given the isoline map (the equipotential lines) for the two-charge system. One has isolines more "squashed together" (more closely ...

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