6
votes
0answers
191 views

Physical interpretation: weighted eigenvalues of the Laplacian with a potential

I'm a mathematician with only the basic knowledge of Physics, so my question may be trivial: in this case, mercy me. :-) Let $\Omega \subseteq \mathbb{R}^N$ be a domain and let $V,m:\Omega \to ...
1
vote
3answers
708 views

Does the Fundamental Frequency in a Vibrating String NOT Necessarily Have the Strongest Amplitude?

I am doing some experiments on musical strings (guitar, piano, etc.). After performing a Fourier Transform on the sound recorded from those string vibrations, I find that the fundamental frequency is ...
1
vote
2answers
140 views

What are the increasingly sophisticated ways to perform a Lorentz transformation?

Since Einstein first derived the Lorentz transformations, their generalisation and execution has changed over the century. So starting with those first derived by Einstein: What are the main, ...
3
votes
4answers
292 views

Does the wave nature of a particle refer to the wave function?

In quantum mechanics when we talk about the wave nature of particles are we referring in fact to the wave function? Does the wave function describes the probability of finding a particle (ex: ...
1
vote
2answers
834 views

Quantum Mechanics by Dirac

I took quantum mechanics from our school's electrical engineering department. It was a grad level class designed for students working in device physics, thus it covered a lot of materials: from the ...
2
votes
2answers
99 views

Is there any correlation between the energy density fluctuations of two separate systems in a vacuum state?

I think the title says it all. What I am curious to find out is if there are any observable changes in the fluctuations of zero-point energy in a vacuum state system that are the consequence of ...
5
votes
4answers
180 views

Why is there still radiation left from the Big Bang now? [duplicate]

Possible Duplicate: Why can we see the cosmic microwave background (CMB)? We all have seen evidence of radiation left from the Big Bang, but how is it still detectable? Why didn't it ...
0
votes
1answer
588 views

Could someone remind me of what we mean by zero electric field “inside” a conductor?

If I have a spherical conductor (perhaps a shell) and "inside", as in the hollow area there is nothing. The electric field is 0. But what happens if there is a charge "inside" (not like inside the ...
0
votes
0answers
50 views

What would happen to Earth if the Sun suddenly disappeared? [duplicate]

Possible Duplicate: If the earth left the solar system for interstellar space. How long would it take for atmosphere to freeze Suppose the Sun simply vanished, what would be the ...
8
votes
2answers
1k views

How can the date of lunar eclipses be calculated by hand?

How can the date of lunar eclipses be calculated? Especially without the aid of a computer.
2
votes
2answers
135 views

May molecules of ideal gases have an inner structure?

The following question is probably very elementary: whether molecules of ideal gases may have optic properties? As far as I understand, when one discusses optic properties, one assumes that molecules ...
3
votes
3answers
1k views

Does radiation change entropy?

Are there entropy changes associated with the transmission of energy from the sun to the earth? Does radiation differ from other modes of heat transfer with respect to the entropy changes? Are the ...
1
vote
1answer
131 views

Does turbulence violate Galilean relativity?

Fluid flows become turbulent beyond a certain velocity. The velocity is almost always with respect to a fixed boundary. However, an observer in a frame of reference travelling with the fluid will also ...
2
votes
1answer
225 views

How many sigma did the discovery of the W boson have?

When the W boson was discovered in the 1980s, nobody spoke of sigmas. How many sigmas was it at that time?
2
votes
1answer
185 views

Newton's law of gravitation in complex form

In an ebook about elementary complex analysis I came across Newton's law of universal gravitation with a complex valued function in place of $r(t)$. Can somebody please explain the intuition about how ...
5
votes
2answers
446 views

Winding number in the topology of magnetic monopoles

I am reading on magnetic monopoles from a variety of sources, eg. the Jeff Harvey lectures.. It talks about something called the winding $N$, which is used to calculate the magnetic flux. I searched ...
1
vote
2answers
3k views

Why does Joule-Thomson expansion of a gas do no (external) work?

I understand one of the benefits of the Hampson-Linde cycle is that there are no cold-side moving parts, but isn't one losing an awful lot of energy in the throttling process? There must be something ...
3
votes
3answers
2k views

How to calculate time dilation in approaching speed of light

If a spaceship travels close to the speed of light (say, at 0.9c), how do I calculate the time as the spaceship pilot experience it? I thought the formula was $$t = \frac{t_0}{\sqrt{1-v^2/c^2}}$$ ...
6
votes
1answer
723 views

The gravitational potential of ellipsoid

In the literature (Kirchhoff G. - Mechanic (1897), Lecture 18 or Lamb, H. - Hydrodynamics (1879)) one can find the following analytical closed form expression for the gravitational potential of ...
1
vote
3answers
384 views

What is the reason behind specific values for charge of electrons, protons?

Why do things like protons and neutrons have specific values. Also speed of light is a speed in which even if you go towards it, the speed does not vary. But why does light have to travel at speed?
0
votes
1answer
129 views

Does regular sky clouds stops the sun's ultraviolet rays?

I have an argue with an ex-Doctor of Medicine about the amount of ultraviolet light reaching us under the clear day sun and under the 100% cloudy sky. To what extent we can say that the sky clouds ...
0
votes
0answers
56 views

How is the universe expanding? [duplicate]

Possible Duplicate: spacetime expansion and universe expansion? Is the space between planets is growing or the space between stars is growing or the space between galaxies is growing?
1
vote
1answer
107 views

dimensional analysis for gravitational radiation expression

on this paper, please refer to equation 2.117 for the power emitted for a rotating mass system: $$ P = - \frac{128}{5} G M^2 R^4 \Omega^6 $$ power in cgs should be (g is grams, m is meter, s is ...
2
votes
2answers
195 views

Batting averages of the Large Hadron Collider

As I understand it, the Large Hadron Collider's function is to throw particles into each other while avoiding hitting the nucleus? If quantum mechanics dictate the position of a particle can only ...
0
votes
1answer
68 views

Tower redshift paradox

If photons are emitted at intervals a, from the top of a tower of height $h$, down to earth, is this formula correct for the intervals b in which they are received at earth? $b=a(1-gh/c^2)$ If so, how ...
2
votes
1answer
2k views

Why did my frozen water bottle explode when I opened it after it defrosted a bit?

Last night I filled a 20 fl oz bottle (http://www.thenibble.com/reviews/main/beverages/soft-drinks/boylans-mash.asp) with lukewarm water from my tap. I filled the bottle pretty much to the brim, ...
2
votes
2answers
1k views

How to calculate speed difference between objects close to the speed of light?

If two different objects (for example two rockets) move in opposite direction at close to the speed of light (for example 0.8c and 0.9c), how do I calculate the difference in speed between the two ...
0
votes
1answer
345 views

Solution to the Maxwell's equation

Question goes as Show that the solutions to the Maxwell's equations $$ \nabla \times \vec H = \frac 1 c \frac{\partial \vec E}{\partial t}+\frac {4\pi} c \vec J, \hspace{ 2 mm} \nabla \times ...
-1
votes
1answer
186 views

What is Supersymmetry (SuSy)? [closed]

In particle physics, supersymmetry (often abbreviated SUSY) is a symmetry that relates elementary particles...etc. what is symmetry breaking? What is supersymmetry (SUSY)? What is spontaneous ...
0
votes
3answers
1k views

Parallel or series connection?

Are C1, C2 and C3 connected in parallel, or C2, C3 in parallel and C1 in series with C23? Btw it appeared as a question in the basic physics Albanian A-levels yesterday. You had to find the ...
1
vote
1answer
495 views

Imaginary voltage in simple RC circuit

As a homework assignment, we have to find $U_a(\omega)$, that is the voltage that drops over the right resistor in relation to the frequency $\omega$ of the input AC voltage $U_e$. For the two ...
4
votes
2answers
532 views

Where do I start with Non-Euclidean Geometry?

I've been trying to grok General Relativity for a while now, and I've been having some trouble. Many physics textbooks gloss over the subject with an "it's too advanced for this medium", and many ...
2
votes
1answer
223 views

Man on treadmill and energy/mass conservation

Suppose we put a very obese man inside a large air tight isolated room with a treadmill and he runs on the treadmill for 24 hours and at the end of the day he sees his weight has come down (mostly ...
1
vote
2answers
132 views

$\Omega_{r}$ from WMAP results?

To do some Friedmann-Lemaître cosmology calculations, I would like to know an estimation of $\Omega_{r_0}$ ($\Omega$ radiation today). WMAP 7 give estimation of $\Omega_{b}$, $\Omega_{c}$ and ...
3
votes
4answers
2k views

What is meant by “Nothing” in Physics/Quantum Mechanics(QM)?

I am not a phycisist, so please forgive my ignorance. This is related to my posts and this. I am trying to undertand what is meant by the term "Nothing" in physics or Quantum Mechanics since it seems ...
0
votes
1answer
839 views

How to calculate specific heat capacity of an alloy

I have done an experiment in which I measured the specific heat capacity of a coin. I would like to compare the results to the actual value. I have found out that the coin is made of Cupronickel alloy ...
4
votes
0answers
295 views

Superposition of Negative and Positive Energy States

This is a question about the negative energy solutions to the free particle Dirac Equation in the first quantized picture. We need both the positive and negative energy solutions to have a complete ...
-1
votes
1answer
462 views

parallel universe- are there an infinite amount of universes?

Parallel universe: in every universe, you are presented with a different decision. Does that mean there are an infinite amount of parallel universes? I.e., if in one universe I choose to go left, I am ...
1
vote
1answer
875 views

Continuity equation for compressible fluid

A question is given as Consider a fluid of density $ \rho(x, y, z, t) $ which moves with velocity $v(x, y, z, t) $ without sources or sink. Show that $ \nabla \cdot \vec J + \frac{\partial \rho ...
4
votes
3answers
264 views

Extending mixed states to pure state

Let us consider any pure state $|\psi\rangle\in\mathbb{C^n\otimes C^n\otimes C^n}$. Its reduced bipartite density matrix represent a pure state or mixed state depending on whether $|\psi\rangle$ is ...
-2
votes
2answers
134 views

(Iran's nuclear timetable) How IAEA knows that iran is able to make nuclear bombs in four months? [closed]

'Iran could have enough material for bomb within 4 months' actually its within 3 months now. I feel, iran will be able to produce nuclear weapons, given the weakness of Western. because West has no ...
0
votes
2answers
116 views

What is gravitational speed for a black hole? [duplicate]

Possible Duplicate: What is the escape velocity of a Black Hole? This is gravitational speed for earth: $$v=\sqrt {g_{e}r}.$$ What is gravitational speed for a black hole? I want an ...
2
votes
2answers
245 views

The shape of the earth$\ldots$

....is an oblate spheroid because centrifugal force stretches the tropical regions to a point farther from the center than they would be if the planet did not rotate. So we all learned in childhood, ...
7
votes
4answers
408 views

Names, maps for Milky Way dust clouds?

There is a nice image of the Milky Way, labeled with constellations, at 360°x45° panorama with constellations: It leads me to wonder how much we know about the Great Rift, Coalsack and other ...
2
votes
2answers
30 views

What physical interactions actually make single stars leave their binary companions at formation?

From an interesting ScienceDaily article, I read this Before the groups of stars disperse, binary stars move through their birth sites and the group studied how they interact with other stars ...
0
votes
0answers
78 views

polarization - quantum point of view

polarization could be easily imagined in classical model: direction of E vector. is there any simple image for polarization of single photon?
4
votes
1answer
145 views

How should one interpret the de Sitter slicings?

When 'constructing' the usual de Sitter space in $\mathcal{M^5}$ by invoking the contraint $-X^{2}_{0} +X^{2}_{1} +X^{2}_{2} +X^{2}_{3} + X^{2}_{4} = \alpha^2$ we quickly see that we end up with a ...
4
votes
1answer
581 views

Are all bose-einstein condensates superfluid?

I feel like the answer should be "no" since all superfluids are not strictly BEC since they can undergo a Kosterlitz–Thouless transition in 2D, for example. I believe the ideal gas isn't superfluid, ...
0
votes
1answer
88 views

Future of colliders and technical limitations

Are there any technical limitations (theoretical or technological) that prevent quark based colliders? ie. Colliding two quarks together.
4
votes
1answer
254 views

Lepton Number Conservation

What is the global symmetry of the electroweak Lagrangian that gives rise to lepton number conservation? As I understand it, electric charge is some linear combination of the conserved quantities ...

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