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 ...
-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
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
0answers
31 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 ...
-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
21 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: ...
1
vote
1answer
29 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 ...
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
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 ...
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??
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
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 ...
3
votes
1answer
46 views

Why is the Force of Friction Equation So Simple?

The general equation for the force of friction (static or kinetic) is $F_f = \mu * F_N$, where $F_f$ is the force of friction and $\mu$ is the coefficient of friction (its value is dependent upon the ...
-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 ...
4
votes
3answers
355 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 ...
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 ...
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. ...
1
vote
1answer
82 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. ...
4
votes
5answers
390 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 ...
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
43 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 ...
-1
votes
0answers
65 views

Lightning strikes causing nudity [on hold]

Klutz's Zap Science states on p. 62: Ever Had Your Sweat Explode? A few survivors of lightning strikes — after recovering consciousness — have found themselves lying on the ground, groggy, ...
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 = ...
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
0answers
33 views

Where does light go when you switch it off? [duplicate]

I have a lamp. When I switch it on, it immediately illuminates the surroundings. When I switch it off, the light goes away in an instant. Why is this? Where do the light particles go? Do they quickly ...
1
vote
0answers
13 views

Cartoon shape cutout at high velocities

I was recently reading this, and Floris's answer confirmed my knowledge that the information of an collision travels at the speed of sound. While I was thinking about that, my mind wandered and I ...
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 ...
2
votes
0answers
40 views

Heads, Tails… Edge?

No Nobel prizes at stake, but just an idle thought and an idle question. How could one calculate the probability of a flipped coin landing stable on its edge, instead of heads or tails? I assume ...
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 ...
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 ...
2
votes
4answers
407 views

Exploring beyond event horizons

In the expanding universe the velocity of separation between galaxies depends upon how far they are. If they are much far away will they have relative velocity of separation greater than speed of ...
0
votes
0answers
35 views

Understanding the advantage of using integration over summation for finding COM for a continuous body?

My book (NCERT) writes: In a rigid body, such as a metre stick, the number of particles is so large that it is impossible to carry out the summations over individual particles. Since the spacing ...
5
votes
2answers
198 views

Wave function in quantum mechanics

I was wondering about something while studying quantum mechanics. If the wave function collapses when measuring a particle and assumes a single position, how do we know that it was a wave in the first ...
5
votes
1answer
151 views

Making precise the statement “particles are excitations in a quantum field”

I've been trying to self teach QFT lately. I find that the basic physical idea makes sense, and I can keep up with the mathematical formalism without too much trouble, but I'm having trouble ...
2
votes
0answers
31 views

What are some good physics websites for learning in general? [duplicate]

As a 17-year-old who is interested in physics and especially in the laws of the universe, what are some good websites that are clear explanations and straight to the point?
1
vote
0answers
28 views

Independence of thermodynamic variables

A given thermodynamical system has a number of state variables, not all of which are independent. Suppose that we have a system which can be specified by $k+1$ extensive variables: $U,X_1,\cdots,X_k$. ...
1
vote
1answer
37 views

Why two-particle wavefunctions are separable and their corresponding particles are indistiguishable at the same time?

If the wavefunction $\psi(r_1,r_2)$ doesn't represents an entangled state, it is separable: $$\psi(r_1,r_2)=\psi_a(r_1)\psi_b(r_2)$$ In this treatment, we ignore the interaction between two particles ...
2
votes
1answer
38 views

If I kept getting closer and closer to the speed of light, what would be the gravitational effects appearing like to an observer? [duplicate]

Now, with special relativity applied to the scenario of me getting closer and closer to light speed, my mass would increase with respect to the observer, and also my length would contract in the ...
1
vote
0answers
16 views

A modern version of Landau theoretical minimum? [duplicate]

Can anyone point to me any modern books that are similar to Landau's book in scope and depth, these books used to serve as the backbone that determines one’s level of scientific culture, and since ...
0
votes
0answers
19 views

Better gas mileage going fast or slow [duplicate]

In an automobile, do you get better miles per gallon when going faster or slower? Is this question answerable without more information? If more information is needed, assume the following: ...
5
votes
3answers
766 views

Physics & derivatives written in a weird way

I was always taught that $\frac d {dx} (\ln x) = \frac 1 x$. No derivative had as a result any $dx$ words. In a physics book I encountered something like this (error discussion) [there might be a ...
1
vote
0answers
21 views

How to derive the Bhatnagar-Gross-Krook collision integral from Boltzmann one?

Let's have Boltzmann collision integral: $$ I_{coll} =\int d \sigma d^{3}\mathbf p_{1}(ff_{1} - f{'}f{'}_{1})|\mathbf v_{rel}|.\tag{1}\label{1} $$ How to transform $\eqref{1}$ to BGK collision ...
2
votes
0answers
34 views

What is a nucleon field?

A nucleon is either a proton or a neutron. A field is, as John Gribbin says, a physical quantity that has a value for each point in space and time. But what is meant by a nucleon field? Can anybody ...
0
votes
1answer
16 views

Angular velocity of disc from induced motion

I came across a question regarding linear momentum $L$ and it's conservation, however I tried and got confused. It reads: A $40kg$ girl stands on the very edge of a rotating disc of mass $50kg$ and ...

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