1
vote
1answer
83 views

Are wave functions real physical objects? [duplicate]

Are wave functions (ex. electron waves) real physical objects or just mathematical tools. Some researchers say that they have proof that they are real objects. Here's the link. ...
1
vote
0answers
22 views

Coupled wheel and rod (analytical mechanics)

I am struggling with formulating the equations of motion. Put a coordinate system with origin in $O$ ($y$ upwards and $x$ to the right). Label the center of mass of rod $AB$ with $G$. Then $$ ...
0
votes
1answer
10 views

Conditions of friction on constant accleration

If a body is moving with constant acceleration, then what would the frictional force be? Zero In forward direction, In reverse direction all of above
15
votes
6answers
1k views
+500

How was the formula for kinetic energy found, and who found it?

My questions mostly concern the history of physics. Who found the formula for kinetic energy $E_k =\frac{1}{2}mv^{2}$ and how was this formula actually discovered? I've recently watched Leonard ...
10
votes
3answers
1k views
+100

How did Newton discover his third law of motion?

How did Newton discover his third law? Was it his original finding or was it a restatement of someone else's, like the first law coming from Galileo? What initiated the concept of what is now known as ...
-1
votes
0answers
31 views

Which number is bigger, -1 or -2? Discuss your answers by applying examples in Physics [on hold]

Which number is bigger, -1 or -2? Discuss your answers by applying examples in Physics. My answer: -1 is bigger than -2. \begin{align*} \ 3.4 \cdot\ 10 ^{-1} = 0.34 \\ 3.4 \cdot\ 10 ^{-2} = 0.034 ...
0
votes
0answers
9 views

Maybe the difference between contextuality, nonlocality and retrocausality lies in where we draw the boundaries?

If the apparatus lies outside the boundary, we have contextuality. If the apparatus lies inside the boundary, but the measurement occurs after the "final time" boundary, we have retrocausality. If ...
0
votes
2answers
44 views

Charging a spherical capacitance

How could one charge a spherical capacitor with a battery or any other emf source?
0
votes
0answers
32 views

How can the electron be a wave?

I read Rutherford's failed attempt for describing atomic model. Then read the famous model of Bohr and his postulates. Ok, that was fine. But then my book dumbed before me a statement that shocked me: ...
3
votes
1answer
17 views

Difference between spin and polarization of a photon

I understand how one associates the spin of a quantum particle, e.g. of a photon, with intrinsic angular momentum. And in electromagnetism I have always understood the polarization of an EM wave as ...
4
votes
2answers
99 views

What's the connection between the spin of the photon and the polarisation of light?

In view of wave-particle duality, the spin of the photon must have a counterpart in the wave picture: is this polarisation?
0
votes
0answers
6 views

The wave function of transverse one is different from longitude one for convinience?

I use the book Fundamental of Physics Hallidays&Resnick 10th Edition Jearl Walker to study in my physics class while I got myself University Physics with Modern Physics Sears, Zemansky 13th ...
0
votes
1answer
20 views
+50

What will happen to permanent magnet, if we keep same magnetic poles of two magent for long time?

What will happen to permanent magnet's magnetic field or magnetic ability, if we keep same magnetic poles of two permanent magnet for long time? Will any magnetic loss happens over the long period ...
-1
votes
1answer
14 views

In which direction due to a polarizing grid the photon's electric field is oriented?

After a photon passes the slit, is it's electric field oriented perpendicular or parallel to the slit and why this is so?
0
votes
0answers
20 views

Can we solve most of the cosmological questions using the Illustris universe simulation?

The Illustris project (http://illustris-project.org) attempts to simulate the universe in its most accurate form according to their website. With the simulation, they were able to predict the neutral ...
0
votes
1answer
22 views

Quantum cloning of orthonormal states

If I understand correctly, for two orthonormal states $\left|\psi_1\right\rangle$ and $\left|\psi_2\right\rangle$ in the Hilbert space H, there must exist a unitary transformation $U$, such that: ...
4
votes
5answers
393 views

Why does heat lose its energy as we get further away?

Why does heat lose its energy dramatically as I move back? Say I have a fire around 0.5 meters in front of me, I can clearly feel the heat, however, as I move even very slightly back, say 1 meter ...
2
votes
1answer
80 views

Heat diffusion: evanescent waves?

It has been recently pointed out to me that the solution of the heat equation in a semi-infinite material with an oscillating boundary condition at the surface is not an evanescent wave. The argument ...
1
vote
1answer
46 views

Is placing a heater in the coldest part of a room the most efficient place to put it?

I've noticed that stores blow hot air in a "sheet" by doors and windows, which is "where cold air enters". I assume they do this because it saves money and/or keeps the store a uniform temperature. ...
0
votes
2answers
99 views

How to find the amplitude of magnetic field of this plane wave

Because my previous question was short and confusing, it was put on hold. This is my new question, which getes straight to the point. I have an electromagnetic plane wave which has wavelength $λ$ = ...
1
vote
1answer
30 views

How can we take pictures of something billion of light years away?

I have had this question in my mind for a long time, I thought you guys might enlighten me easily. I am confused about some space photographs and claims like "this galaxy is 13 billions light years ...
-5
votes
1answer
82 views

Could it be possible that the universe doesn't exist [on hold]

Could it be possible that the universe doesn't exist? That nothing exists, not even you or me? And by not existing, I mean totally not existing, as in not even existing as a computer simulation, or a ...
7
votes
2answers
233 views

What do units like joule * seconds imply?

I can easily understand what divisive units imply, but not what multiplicative units imply. What I mean is, when I read "12 eggs/carton", I mentally convert it to, "There are 12 eggs for each ...
1
vote
0answers
17 views

Why is the Great Dark Spot so shortliving unlike the Great Red Spot?

The Great Dark Spot is an anti-cyclone in Neptune. But unlike the Great Red Spot of Jupiter which lasts for more than hundred years, the Great Dark Spot exists for only one year or so. Why is it so??
1
vote
0answers
27 views

General Relativity: impact of acceleration on time, experimental setup

In What is relativity by Jeffrey Bennett (Amazon link), the author explains how acceleration/gravity impact time and causes time dilation. For this he takes an example of an accelerating space-ship ...
-1
votes
0answers
30 views

Why is friction independent of contact area, and why does it increase with surface smoothness?

Below there is a line from my book: The force of limiting friction is independent of the apparent area of contact, so long as normal reaction between two bodies in contact remain same. Why is ...
0
votes
0answers
45 views

Is it possible to single out a proton, electron, neutron?

I've read that it's nearly impossible to take a proton from an element. But if it's "nearly" impossible then it is possible to some degree. If this has happened, what is exactly the process of taking ...
3
votes
2answers
85 views

Hamiltonian for a Lagrangian with coupling

I am dealing with the following Lagrangian density $$\mathscr{L}_{em}= -\frac{1}{2}\rho\omega^2 u^2 +\frac{1}{2}\nabla u:\Sigma :\nabla ...
0
votes
2answers
33 views

Could we describe acids and bases using electromagnetism?

Why don't we use Maxwell's equations in acids and base theory? Surely the interaction between two charged species is readily described by this. The theory I have so far come across is HASB theory. ...
1
vote
1answer
46 views

How fast am I moving?

Given the speed of light is 299,792,458 meters per second and that it is constant through out the universe, (i.e a person who measures the speed of light while standing still will get the same result ...
1
vote
0answers
25 views

Predicting balls's movement in well due to fluid flow

I am a total newbie in fluid dynamics. In one of my experiments/open project, my experiment setup is as below: a small ball sits in a circular well (has mass density a bit heavier than water), with ...
3
votes
1answer
44 views

What topics do I need to study electromagnetism on the quantum scale? [on hold]

What topics do I need to study (in order) so that I can study electromagnetics on the quantum scale? What is the name of the discipline studying electromagnetism on the quantum scale? Do I need to ...
1
vote
0answers
37 views

How are the Lorentz force, Maxwell's third law and Faraday's law of induction clasically related?

Faraday's law of induction can be used in any situation where the magnetic flux is changing through a closed conducting loop. While giving the correct answer, it seems to me that for the following ...
2
votes
0answers
24 views

Pion decay: V-A vs. V coupling

For the Decay $$ \pi^+ \to \mu^- \bar{\nu}_\mu $$ the Feynman rules for this tell us that the vertex couples with $\gamma^\mu (1-\gamma^5) / \sqrt{2} $. This gives me the reduced amplitude of $$ M = ...
2
votes
1answer
33 views

Measuring the pressure in a container without altering it

Let's say I have a closed, non-transparent metal container with pressurized gas and I'd like to measure the pressure inside without altering it (the pressure should stay the same), is thatpossible ? ...
0
votes
0answers
41 views

What does the relation between mass and energy of a free particle mean?

What does the Hamiltonian for a free particle mean? Does it mean that the kinetic energy of the particle is in reverse relation with mass? $H$ or $E=\hbar^{2}k^{2}/2m$. Or, what's the relation ...
0
votes
0answers
17 views

Calculating buoyant force of air experimentally

I'm planning a physics project to submit at school and since it has to be something where we experimentally determine some value, previously known theoretically, I had this following idea but I want ...
7
votes
1answer
147 views

2 Component Spinor Formalism

In Chapters 34-36 of the Srednicki QFT book, 2 component spinors and their combinations in Dirac and Majorana spinors are carefully constructed. Specifically, in equations 36.14 and 36.15 the ...
15
votes
5answers
950 views

What was the entropy of the universe at the time of the Big Bang?

(I asked this question in Philosophy.SE; but I was advised to direct it here, despite it is, in my opinion, somewhat too speculative for physics.SE). High entropy generally means high disorder; and ...
2
votes
2answers
98 views

Energy Stored in a Capacitor with and without Dielectric

I have seen the equation $V = \frac {V_0}{K}$, but also the equation $V=\frac{1}{2}CV^2$. The values of C and V increase in the same linear ration with K (because $C=KC_0$). However, as the energy ...
1
vote
1answer
26 views

Why are position and velocity enough for prediction and acceleration is unnecessary?

In classical mechanics, if you take a snapshot and get the momentary positions and velocities of all particles in a system, you can derive all past and future paths of the particles. It doesn't seem ...
14
votes
1answer
1k views

Why does the tongue stick to a metal pole in the winter?

since the Christmas season is here, I would like to ask a question about the movie, "A Christmas Story." In one of the subplots of the movie, Ralphie's friends were betting each other that their ...
2
votes
7answers
5k views

Why is the charge transferred by electrons and not by protons?

charges are transferred by electrons which we all know but why it cant but it cant be transferred by protons.Well i searched on google where i found similar questions already being asked on many ...
1
vote
1answer
34 views

Question concerning the diagram for stress tensor

I have a couple of questions related to the diagram in the answer by Kyle Kanos to this question, Why is stress a tensor quantity?. Q1. If the box shown is of finite size why are there not three ...
0
votes
1answer
65 views

Thermodynamics phase change question

why is specific volume of Saturated water greater at 1 MPA than at 0.1 MPA during the phase change process check out the T-V diagram here in the link. ...
4
votes
3answers
360 views

How much heat from a fire actually warms your home?

A fire in a hearth disperses heat to, I guess, three places: the bricks of the chimney out the hearth (where the person tending the fire is standing) out the chimney, above the house How would you ...
18
votes
7answers
1k views

Does the weight of an hourglass change when sands are falling inside?

An hourglass H weighs h. When it's placed on a scale with all the sand rested in the lower portion, the scale reads weight x where x = h. Now, if you turn the hourglass upside down to let the sand ...
3
votes
2answers
137 views

How to find the center of mass of several objects in a 2d plane?

We have the following scenario in a 2d plane: a big rectangle with a lot of smaller similar uniform rectangles in it, all of them weight differently. Where is the center of mass of this object ...
5
votes
4answers
183 views

Particles scattering on fluids: breakdown of the effective continuum description

When does the macroscopic continuum description of a medium like a fluid break down? Say I'm interested in a scattering process of some particles with momentum $p$ and energy $E$ off a fluid of ...
1
vote
0answers
58 views

Why $D^{\mu} D^{\nu} F_{\mu \nu}=0$ ? (Noether Identity) [on hold]

I have to show that: $$D^{\mu} D^{\nu} F^A_{\mu \nu}=0$$ vanish identically. This is the generalization to non Abelian groups of $\partial^{\mu} \partial^{\nu} F_{\mu \nu}=0$, apparently called ...

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