0
votes
1answer
66 views

Differential cross section $d\sigma/dp^{\gamma}_{T}$?

Why we care about $d\sigma/dp^{\gamma}_{T}$? What the physical meaning of it? Why not plot $\sigma$ follow $p^{\gamma}_{T}$?. As in this picture.
1
vote
2answers
79 views

The observer experiment: quantum mechanics

If an observer is needed to see something, but it is an observer that causes a quantum wave function to "collapse" into a classical state, how could we tell that the quantum wave function even existed ...
0
votes
0answers
54 views

Can current be stopped using magnetic field?

Is it possible to stop a current "running" through wire only by using a magnetic field around the wire?
0
votes
1answer
34 views

Using gravity assitance or turn to return back a spacecraft

I wonder why gravity assist is not also used to return missions back to Earth? I assume the space shuttle is too expensive with its accessories and could be a money and time saving to reuse it, ...
3
votes
1answer
73 views

Mechanical waves with slower speed than sound

Sound is mechanical waves of high and low air pressure transmitting with 300m/s. Are there high and low air pressure waves transmitting with lower speeds? How are they produced?
0
votes
1answer
94 views

One person catch? [closed]

Starting from rest, a child throws a ball of mass m with an initial speed v , at an angle B with the horizontal direction. The child then chases after the ball, accelerating at a constant ...
2
votes
2answers
145 views

Possible paradox with black holes and time dilation [duplicate]

I am by no means an expert in the realm of physics. I do from time to time, try to understand the concepts of modern physics and their applications. I came across this video that I am currently ...
9
votes
5answers
829 views

Is double-slit experiment dependent on rate at which electrons are fired at slit?

I am a mathematician and I am studying string theory. For this purpose I studied quantum theory. After reading Feynman's book in which he described the double-slit experiment (Young's experiment) I ...
0
votes
0answers
102 views

Surface current density and infinite solenoid

I have an infinitely long cylinder with radius $R$ and axis lying on the $z-$axis, charged with volume density $\rho$ and surface density $\sigma$. The cylinder is spinning with angular velocity ...
0
votes
0answers
44 views

Topological configurations and phase transitions

It is known that topological defects might appear only during phase transitions of the first kind, while continuous transitions of the second kind and crossovers don't product them. How to explain ...
0
votes
1answer
162 views

How does measurement affect multi-particle entangled particles?

It is my understanding that you can have two entangled particles, A and B, and measure their spins from two different angles, X and Y, such that: If you measure A using one angle (e.g. X), there's ...
-1
votes
1answer
50 views

Superstrings in the 10th Dimension [closed]

Physicists say that the superstrings vibrating in the 10th dimension are what create the subatomic particles that make up our universe and all other possible universes as well. If that is true, ...
1
vote
0answers
127 views

What are the longest half-lives we can detect experimentally? What stops us going further? Are we trying to?

Xenon 136, apparently, has a half-life of 2.11×1021 years. This strikes me as a humongously long time to run an experiment, clocking in at about 11 orders of magnitude longer than the age of the ...
2
votes
1answer
59 views

Is surface brightness constant as a function of distance?

Well of course it is - the flux drops off as the square of the distance, but the solid angle subtended by the source drops off the same way, so surface brightness is constant, right? Yet other ...
0
votes
1answer
72 views

Classical Computation without NOT [closed]

Is it possible to do universal classical computation using bits and 2-bit gates when you cannot perform a NOT operation on a single bit (hence cant do CNOT and so on). If yes, what are the possible ...
1
vote
0answers
52 views

Can i use the $y^*$ representation of the chiral covariant derivatives on a superfield that contains both $y$ and $y^*$?

Imagine I want to compute this $$D^{\dagger2}D_{\alpha}(\Phi^*\Phi)$$ where the $D$-s are super-covariant derivatives and $\Phi$ is a chiral superfield. Following the notation of this review on ...
0
votes
4answers
124 views

What effect does direction have on special relativity?

Okay, so here's what I'm stuck on. First imagine there is an observer (observor A) on a train heading west at half the speed of light. It is chasing a beam of light. There is another observer ...
2
votes
1answer
77 views

Does relativity objectively define entropy?

In his undergraduate text "Spacetime Physics", Wheeler points out that there is always a fourth component to momentum and energy interactions, because the internal motion of the objects involved will ...
0
votes
0answers
57 views

How can I compute the orbit of a Higgs field?

In many papers that deal with symmetry breaking a concept called orbit is introduced: It is worth noting that if the potential is a minimum $\phi_0$ at a value of the field, then from (3.13) it is ...
0
votes
1answer
46 views

What is the Proper way to determine overall velocity in a pipe?

I am running a simulation of fluid in a pipe. The fluid in this pipe is "swirling" (instead of just moving in one direction, it's rotating as well. Like the Helix below. The fluid is faster on the ...
1
vote
1answer
77 views

About the rotating speed of a light beam which has been reflected off a rotating mirror [closed]

A light beam generated from a source reaches a rotating mirror (x m away from the source), and is reflected off to a fixed mirror ( x m from the rotating mirror ), and again back to the rotating ...
1
vote
4answers
813 views

What exactly is meant by infinity?

What exactly is meant by infinity when I see it in a physics equation (always something wrong?)? And in experiment how many orders of magnitude can be treated as infinity (say, if infinity is ...
0
votes
3answers
172 views

How to apply Newton's first law to moving object?

I'm new to many forces, such as gravity and friction, and I don't really know how they work. I'm trying to simulate a ball bouncing with a program, and it travels at a constant speed horizontally. I ...
1
vote
1answer
151 views

Does the Inverse Square Law apply for all frequencies of sound?

We often seem to only hear the lower beats of music far away, whilst the higher frequency sounds seem to diminish more quickly - remaining unheard. I know that sounds with higher frequency have ...
1
vote
1answer
119 views

What is the defintion of a current-current diagram?

Right now I am facing some Feynman diagram calculations and in the instructions I am reading the phrase current-current diagram appears quite often so I wanted to know: What is the definition of a ...
5
votes
2answers
341 views

How does one write Newtons 2nd Law using the language of forms?

Newton's second law says that $F=ma$. Supposing that the force is conservative and can thus be expressed in terms of a potential $V$ we have that $F=-dV$. We have that $V$, being a function, can ...
1
vote
2answers
98 views

Why things wobble when submitted to wind?

If I place a little piece of paper in front of a fan, it is going to wobble/oscillate. Is it because the wind flow isn't constant ? Or because the air movement makes the piece of paper move away, so ...
1
vote
0answers
32 views

How is it possible to combine various techniques in cold atom experiments?

I’ve been reading about laser-trapped cold atoms (6Li in particular, which is a fermion) and was amazed at the number of things to keep track of in the experiments, just to gain that degree of control ...
0
votes
2answers
84 views

Solid Mechanics book recommendations

I'm searching for a book on Solid Mechanics that explains the topics intuitively (similar to Kline explanations on Calculus: An Intuitive and Physical Approach). Also the book should have the ...
1
vote
1answer
140 views

Angle between two momenta in particle physics (principal axis of a two-body decay vs. center-of-mass motion in the lab)

Situation: I have events with a W-Boson decaying into two leptons (e.g. electron and electron-neutrino). Now I want to see, whether there is an angle range into which the leptons are emitted ...
0
votes
1answer
894 views

What is the cause of the surface tension of the liquids? [duplicate]

What is the cause of the surface tension of the liquids? How to know the direction of tension force on the free surface of the liquid? I know that the surface tension is the force acting normally ...
1
vote
3answers
331 views

Why does noble gas electron configuration have low energy?

In chemistry classes in primary school we learned that atoms "want" to reach noble gas configuration because it have low energy, so atoms on the left of the periodic table are willing to give away ...
0
votes
0answers
17 views

Averaging Multiple Load Graph Values

I'm aware this is a problem of statistical analysis, but given my background in physics and the physical nature of the problem I felt it was best to ask this question in this SE rather than ...
0
votes
1answer
34 views

Wideband metamaterials in mobile-telecommunications bands

Were there any metamaterials (materials, settings, geometry) studied that are non-resonant (not frequency selective) in the frequencies between 700 MHz and 2700 MHz, therefore useful for mobile ...
1
vote
1answer
35 views

Layer of graphene on reflector of an antenna

First of all I have no idea how well graphene "sticks" to other metals, but let's suppose it does (well, if I may please ask you to reply to the "stick" question too...). Given the material great ...
5
votes
1answer
187 views

what happens inside linear polarizer sheet (at microscopic level) when unpolarized light falls on it?

(1) What happens at microscopic level when unpolarized light falls on a linear polarizer sheet ? i.e. Due to what thing inside polarizer sheet, only those EM waves are passed whose plane of vibration ...
0
votes
1answer
79 views

Net work done by projectiles?

When the projectile is in motion what is the net work done on projectiles? What i think? 0 first view: We know when we throw projectiles the initial KE and final KE is 0. So from work energy ...
0
votes
0answers
44 views

Heat Retention of Wine

This may seem odd and lengthy but I am going to attempt to consolidate my thoughts as much as possible. I'm sorry in advance for the length of my post and if this is confusing. I am currently ...
0
votes
0answers
140 views

Which is has the highest (greatest) sound intensity - Sine, Square or Sawtooth waveform?

From this, http://electronics.stackexchange.com/questions/42904/square-wave-sine-wave-is-more-audible I now understand that a Square soundwave will be perceived louder than that of a Sine sound wave ...
0
votes
2answers
220 views

Why must heat supplied in the definition of entropy be reversible? Can't it be irreversible after all it is a state function?

The definition of entropy contains the term $Q_\text{rev}$ which means the heat supplied or taken out reversibly. I thought yes it can be after all only the initial & final states are important as ...
2
votes
2answers
1k views

If two objects have all the same conditions except different masses. Will their terminal velocity be different?

I can't seem to find a straight forward answer to this. I really just want to know if changing mass of an object affects the terminal velocity. If two objects of the same dimensions except one had ...
0
votes
1answer
323 views

Force between two solenoids

How does one calculate the magnetic force between two coaxial solenoids, placed in a way their currents are in the same sense? There is a simple way to treat both as dipoles and then calculate the ...
1
vote
1answer
150 views

How to calculate relative humidity from specific humidity and temperature?

If I know specific humidity and temperature at a location, can I calculate relative humidity using these two?
0
votes
1answer
87 views

Can QED explain this or do I have revert to the classical model of light?

I want to know can QED can explain this image,like why there are someplaces with low light (shadows) like behind the chair, and why there are some places that are bright(rest of the floor). I know ...
0
votes
2answers
100 views

How does a Black hole attract light? [duplicate]

Please no hate for lack of knowledge: I am somewhat fascinated with the subject of black holes. However, I do not understand a concept which is constantly attributed with black holes: that a black ...
0
votes
1answer
99 views

How to produce a 3D density map of a time-depenent system of particles?

I have a time-dependent system of varying number of particles (~100k particles). In fact, each particle represents an interaction in a 3D space with a particular strength. Thus, each particle has ...
2
votes
0answers
103 views

How does lightning flip a car?

http://www.standard.co.uk/news/london/car-flips-into-air-after-being-struck-by-lightning-in-freak-electrical-storm-accident-10366208.html and a few others ...
5
votes
1answer
142 views

Does QFT prevent preparation of an entangled particle pair as in EPR experiment?

This is the claim Tommasini makes in Reality, Measurement and Locality in Quantum Field Theory:"Two spin $1/2$ particles, A and B, are created in coincidence in a spin-singlet state, and are detected ...
2
votes
0answers
91 views

How do quarks have no spatial extent?

I found an answer to a question I had and that is that quarks have no spatial extent. But how is that possible? Everything has to have some spatial extent; to keep continuing on and on, right?
0
votes
0answers
69 views

How to determine how much torque a hollow cylinder can take?

I'd like to calculate how much torque a hollow cylinder along its axis can take before it will start to buckle. The cylinder is held at one end, and the torque is applied equally in discrete ...

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