0
votes
1answer
7 views

In the double slit experiment, what happens when there is more than one observer trying to see which slit the same electron goes through?

From all the demonstrations Iv been able to find of Heisenberg's double slit experiment, whenever an observer tries to "see" which slit an electron passes through it collapses the wave function. My ...
2
votes
0answers
19 views

$\mathrm{CO_2}$ rate of deposition

Parts of Antarctica average -127°F (-83°C). The freezing point of $\mathrm{CO_2}$ is -109.3 °F (-78.5 °C). If one could construct a large container at such a place shielded from the sun, would ...
1
vote
2answers
15 views

Radioactivity features

What happens if someone would make a wire coil around nuclear reactor core? What are the possibility to capture radioactivity directly?
1
vote
0answers
28 views

What is light and how does it travel?

My question is: What is light, and, more specifically, how does it travel? I've been contemplating a theory that I watched on Youtube (which has no real credibility to my knowledge), the Cosmic ...
1
vote
2answers
26 views

How can I split a resultant force into its $x$ and $y$ components?

Point charge 3.5μC is located at x = 0, y = 0.30 m, point charge -3.5μC is located at x = 0 y = -0.30 m. What are (a)the magnitude and (b)direction of the total electric force that these charges ...
1
vote
1answer
40 views

Quantum Yang-Mills Theory and AdS/CFT

I just read the first chapter of Becker-Becker-Schwarz. To quote: A remarkable discovery made in the late 1990s is the exact equivalence (or duality) of conformally invariant quantum field ...
0
votes
1answer
10 views

Does the pressure in a pressure tank depend on the amount of air?

I have a pressure tank which is filled with water and air. What want to know is: if I change the ammount of air in the tank would the ammount of water that leaves the tank, when pressurized, change? ...
0
votes
2answers
21 views

Calories Burned While Hiking

I want to find out how many calories are burned on any particular hike by any particular by using a formula. I figure it's probably a simple physics question, but since I never took physics, I don't ...
1
vote
2answers
19 views

Force on every particle?

Say there is a horizontal rod, where a force $P$ is applied to the right hand side of the rod to drag it horizontally to the right. If I drew a force diagram, I'd put some vector with a length of $\| ...
1
vote
1answer
18 views

Mass of small fluctuation around vacuum

For a potential $V$, how do we define the mass of a small fluctuation around its vacuum? For example I have the potential $$ V_\mathrm{eff}(\phi) = \frac{1}{2} \left(\frac{\rho}{M^2} - \mu^2\right) ...
1
vote
0answers
15 views

Why photon has a wave nature?

Wave theory does not account for the photon model, which was developed only to explain quantum effects like photoelectric effect. Then why do we talk about a photon's reflection and rarefaction, as ...
0
votes
0answers
12 views

Angular and Linear Acceleration

Imagine a rod attached at one end to a solid wall. It has a hinge where it is attached to the wall, which allows it to rotate. Hold the rod perpendicular to the wall. In the instant you release it, ...
0
votes
1answer
7 views

What is the space/time effect of an exploding supernova?

If the flow of energy -- or the flow of time/light/space? -- in "empty" space is distorted when meeting an object such as a planet, flowing around the object in a distortion of space/time that also ...
-2
votes
0answers
22 views

How to convert 1atm to kj/m3 [on hold]

I am trying solve similar questikn like this myweb.loras.edu/cm418218/EGR334/HW%2019%20Solutions%20Spring%202012.docx 13th slide but in si unit i just want to know how to convert 1atm to kj/m3 in ...
1
vote
2answers
20 views

Can an arrangement of particles be duplicated precisly?

Is it possible to teleport or clone someone or something? After watching this TED talk by Max Tegmark - https://www.youtube.com/watch?v=GzCvlFRISIM I find myself wondering if it is then possible to ...
0
votes
0answers
28 views

How can light travel at speed of light? [duplicate]

I am well aware that the speed of light is a universal constant at which nothing but light can travel. But why? Why can even light travel at such a speed? Our maths tell us that anything with rest ...
0
votes
1answer
23 views

Can someone explain effects of time dilation on expansion of universe

I'm not a physics guy, but this is something I have always wondered about. If a clock flown by an object of high mass runs slower, what is the effect of this in regards to the density of the universe. ...
2
votes
1answer
15 views

World-sheet energy-momentum tensor and OPE

On p43 of Polchinski's book, it says that under the world-sheet translation $\sigma^a\rightarrow\sigma^a+\epsilon v^a$, $X^\mu\rightarrow X^\mu-\epsilon v^a\partial_a X^\mu$. And $$j^a=iv^b T_{ab},$$ ...
1
vote
1answer
21 views

What exactly happens to an exposed human body in space?

I know that space is a vacuum, has no air and is very, very cold. from what i have seen in movies and TV shows when a space suit is exposed the oxygen will escape will escape like a visible gas and ...
0
votes
0answers
16 views

Algorithm of Patankar for Numerical Heat Transfer and Fluid Flow [on hold]

I look for the algorithm of Patankar (for exemple: SIMPLE, SIMPLER, ...
2
votes
1answer
621 views

How cold would a bowling ball near absolute zero make a room?

If a bowling ball at absolute zero suddenly appeared in my room, how cold would the room get? Would I die? My initial estimation is that it one bowling ball at 0K (i.e., 300K below room temperature) ...
0
votes
1answer
38 views

Minkowski spacetime vs Euclidian space

Two questions marked in bold: What is the magnitude of a Minkowski spacetime four vector? I'm deducing that it is c for all observers, and that it is a velocity vector. In Euclidian space, a ...
1
vote
0answers
6 views

Convention about delta x in Waves Interference

http://imgur.com/oxFF7q8 They seem to adopt a convention that delta x must always be positive. Otherwise, there is no way to know what the phase difference of the sources actually means. Does a ...
1
vote
0answers
25 views

Supergravity solution, metric for the total space, and connection

In supergravity solutions, one sometimes encounters the case where the manifold may be a bundle over some base space, and one has to write down the explicit metric regarding such bundle. I would like ...
0
votes
1answer
21 views

Reflected waves and phase changes

If a wave passes from a lightweight string to a higher density string, we say that the reflected wave has a pi phase change. Can we say that it has minus pi phase change? If yes, why would that not ...
0
votes
1answer
37 views

Would equations for a spinning top be an (x,y,z) vector [duplicate]

I am following the equations on this page, and for torque it is $mgr\sin\theta$, but I am curious about $r$. I am working on a game and I want to correctly model the top, and am curious if $r$ should ...
0
votes
0answers
24 views

Calculation of frequency from known beat pattern [on hold]

< Why is the answer 498 Hz and not 502 Hz? The difference between the two frequency is 2.
2
votes
1answer
40 views

Rate of change of a normalised wave function

I'm reading Weinberg's Lectures on QM. On top of p23 it says $$i\hbar\frac{d}{dt}\int|\psi(x,t)|^2d^3x=i\hbar\int\psi^*(x,t)\frac{\partial}{\partial ...
2
votes
1answer
65 views

How to weigh your nephew [on hold]

My nephew is 3 and weighs around 30 pounds I am guessing. However, I would like to weigh him at home. I have kitchen scales, one flat one that goes up 1kg and one that looks like this picture that ...
3
votes
0answers
41 views

Bound states in 1D & 2D

Why does Mother Nature allow bound states in arbitrarily weak attractive potential in 2D but not in 3D? See, for example, this article: ...
0
votes
1answer
47 views

Microscopic understanding of Brewster angle

The textbook explanation is that, at Brewster's angle, the electric dipoles excited by the incident light can't reradiate to the reflection direction since it's aligned with the dipole moments. Is ...
4
votes
1answer
517 views

Does dark energy annihilate energy?

Antimatter and matter particles annihilate. But does dark energy annihilate energy? We consider energy to be photons, and such, correct? So when we say energy, we're actually talking about some ...
0
votes
1answer
9 views

Intense of liner polarized wave: with a polarizer vs. without a polarizer differences

We had this experiment in which we measured the intense of linear polarized wave - with and without a polarizer. I noticed that without the polarizer the intense was slightly lower than with the ...
0
votes
0answers
38 views

Can we build large spaceships? [on hold]

Ok, so could we build large ships like the ones on TV? If not, why? Also, is their a way to improve out rocket technology and launch heavier payloads into space for a cheaper cost? If we could build ...
2
votes
1answer
30 views

Bulk-boundary cutoffs in AdS/CFT

I'm studying the holographic entanglement entropy (HEE) in this paper (Ryu-Takayanagi, 2006). In section 6.3 they compute the HEE for a segment in a 2D CFT. To do so, they obtain the corresponding ...
2
votes
1answer
47 views

Refractive index of dielectric in different frames of reference

The setup A transparent isotropic dielectric medium moving in the negative $x'$ direction at speed $v$ in frame $S'$ is stationary in frame $S$, where it has refractive index $n$. In other words, ...
1
vote
1answer
31 views

Ward Identity in CFT

This is about Polchinski's eq(2.3.11). It says that $$Res_{z\rightarrow z_0}j(z)\mathcal A(z_0,\bar z_0)+\bar{Res}_{z\rightarrow z_0}\tilde j(\bar z)\mathcal A(z_0,\bar z_0)=\frac1{i\epsilon}\delta ...
0
votes
0answers
31 views

Finding interaction Hamiltonian for nano particles

I am studying Quantum electrodynamics (QED) and the core part of this theory is the light-matter interaction (quantized light and matter). I referred many papers and books (Molecular quantum ...
8
votes
2answers
321 views

How does escape velocity relate to energy and speed?

I have several confusions regarding escape velocity. I am sure I am missing something(s) obvious or maybe I am taught wrong. Lets say we throw an object of any mass at exactly escape velocity of ...
0
votes
2answers
40 views

Tachyonic field

i'm working on a paper about symmetron cosmology. symmetron is a scalar field that by its symmetry breaking can explain the dark energy. the action is: ans A , V are assumed to be: where M ...
1
vote
0answers
19 views

Sun reaching zenith at a particular latitude

I need to find when the sun reaches the Zenith at a given latitude. What I've done so far: $L=23.5 \cdot \sin(\frac{2\pi}{365.25}\cdot D) $ Here L is the latitude (<23.5) and D is number of days ...
0
votes
0answers
40 views

What is the scalar field mediated force?

I'm working on a paper about symmetron cosmology. Symmetron is a scalar field that by its symmetry breaking can explain the dark energy. the action is: ans A , V are assumed to be: where M ...
0
votes
1answer
33 views

Would days be longer as the polar ice caps melt? [duplicate]

I got question in my mind striking for several days but not able to prove it, suppose polar ice on earth melt, would the days be longer? My friend said it was due to moment of inertia of the earth ...
1
vote
2answers
50 views

Coulomb's Law- Why the Coulomb's law is valid only for point and static charges?

Why the coulomb's law is valid only for point and static charges? Is there is any definite reason?
5
votes
2answers
280 views

Speed of light in general relativity

My question has a few parts concerning the speed of light in general relativity. Firstly, time changes in response to gravity and speed. Therefore, as gravity effects time in an area of space, should ...
0
votes
2answers
43 views

Application of Newton's third law

By newton's third law , we know that every action has an equal and opposite reaction .We move left when we push slightly on the right and move forward as we push backward . But how do rockets , ...
0
votes
2answers
28 views

How do I write the units for this answer? [on hold]

If the force (at 90∘ to the lever arm) applied is 15 N and it is applied at 2.0 m from the pivot point (point of rotation), what is the torque on the lever? Is it 30.0 N/m?
0
votes
2answers
40 views

Electric Field and Calculus: What is the physical significance of infinitesimal $dA$ in the equation of Gauss's Theorem?

In many equations we see infinitesimals $dA$, $dS$, $dx$ and so on. What is is the physical significance of these? Someone told me it signifies a small entity. For example,in case of $dA$ it signifies ...
2
votes
2answers
44 views

Why should an area vector point normal to the surface?

Why is it that the direction of an area vector should be always along the normal drawn to the surface? Can't it also be some other angles with the plane?
2
votes
1answer
434 views

Dark matter a medium for light propagation

Is dark matter a candidate to fill void left by luminiferous ether as a medium for light travel?

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