0
votes
2answers
1k views

Electric field of not-grounded conducting plate with a given potential?

I have been trying to find an equation (or some solution) of how to calculate the electric field strength (in N/C) of a conducting rectangular (nearly flat) plate which has non-zero potential to it, ...
0
votes
1answer
179 views

range of infrared light

I notice in the EMS chart that only half of the IR range will travel through the earth's atmosphere. So in the range of frequencies that penetrate the atmosphere what frequency travels farthest?
2
votes
4answers
285 views

Can we make a change of variables (for example to polar coordinates) into a divergent integral?

I know that if the integral is convergent we can always make a change of variable to make it better, however what happens with DIVERGENT integrals? can we make a change of variable into a divergent ...
2
votes
1answer
604 views

$N$-body simulation in General Relativity

How would one perform an $N$-body simulation in General Relativity (GR) for something like galaxy formation or galactic dynamics? Suppose one wants to simulate the rotation curve $v(r)$ for galaxies ...
3
votes
1answer
20 views

Could asteroseismology have a significant potential to unravel the mechanisms of solar cycles that last thousands of years?

Could asteroseismology have a significant potential to unravel the mechanisms of solar cycles that last thousands of years? And what about solar cycles 1 billion years ago and 2 billion years ago ...
2
votes
3answers
281 views

Hydrogen transition and photon behavior

consider a transition for an electron in the Hydrogen atom from the ground state to the 1st excited state. Let's say this transition occurs through absorption of a photon of exactly the energy ...
2
votes
1answer
126 views

Are the inner planets on planar orbits because there was more dust in the inner solar system (early on in planetary accretion)?

Question inspired by a question thread here. So when there's lots of dust in a galaxy, the galaxy tends to collapse into a spiral galaxy (to maintain angular momentum and to minimize gravitational ...
4
votes
2answers
226 views

Where does a star's angular momentum go as its spin slows down?

So we know that stars slow down as they age. But total angular momentum must be conserved. Where does that angular momentum go? The dissipation of Earth's tides somehow transfers Earth's angular ...
3
votes
3answers
85 views

Distribution of each element and molecule as a function of distance from the Sun and as a function of time

Are there any graphs that show the distribution of each element and molecule as a function of distance from the Sun? And maybe even the time-evolution of each distribution over the solar system's ...
8
votes
7answers
575 views

Are the rest masses of fundamental particles certainly constants?

In particular I am curious if the values of the rest masses of the electron, up/down quark, neutrino and the corresponding particles over the next two generations can be defined as constant or if ...
1
vote
2answers
188 views

Converting Angular Momentum?

I am aware of three apparently different forms of angular momentum: spin, orbital and macroscopic, like a spinning crystal or baseball. Can angular momentum be transferred or converted from one of ...
15
votes
6answers
1k views

Proving that interval preserving transformations are linear

In almost all proofs I've seen of the Lorentz transformations one starts on the assumption that the required transformations are linear. I'm wondering if there is a way to prove the linearity: Prove ...
9
votes
3answers
3k views

How fast does an ice cube melt in a microwave?

I have noticed that when I microwave an ice cube it appears to melt more slowly than I would expect. For example, an equal volume of water starting at 0 deg C would probably be at boiling point before ...
-1
votes
1answer
29 views

Maximum depth for bacteria on rogue planets [closed]

If microscopic life evolves on a planet which is subsequently ejected from orbiting its star, then the planet would cool down. How deep into the interior of the planet could organisms reach, assuming ...
4
votes
1answer
61 views

Vesta dwarf planet status

Now that we have close-up photos of Vesta, which the IAU had previously said was a candidate dwarf planet, when is the IAU going to decide the issue? Personally, Vesta doesn't look round enough to me. ...
7
votes
4answers
820 views

What does ionization of neutral Hydrogen have to do with “transparency”?

Most accounts of the early history of the Universe make some reference to (re)ionization as being the reason that the Universe becomes transparent after a period of opacity caused by the absence of ...
0
votes
3answers
170 views

units of measure

This question is rather historical one. kilometres can be defined in metres, metres in centimetres, centimetres in millimetres. There must be some elementary unit (like millimetre or smth.) which ...
12
votes
3answers
1k views

What are the mathematical problems in introducing Spin 3/2 fermions?

Can the physics complications of introducing spin 3/2 Rarita-Schwinger matter be put in geometric (or other) terms readily accessible to a mathematician?
3
votes
1answer
338 views

SO(3) x SU(2) Symmetry of the Hamiltonian

I have a question converning multiplets when describing atoms. Let $H=\sum\limits_{k=1}^{N} (p_{k}^2 - \frac{Z}{|x_{k}|} + \sum\limits_{i<k}^{1..N} \frac{1}{|x_{i} - x_{k}|}$ be a (self-adjoint) ...
2
votes
3answers
621 views

Understand audio signals

Most audio signal are described by a curve having two parameters: The amplitude and the frequency (amount of time from positive to negative amplitude value). What I want to understand is how the ...
3
votes
1answer
736 views

At what temperature does water become a liquid on Mars? On the asteroids? And in a vacuum?

I know that I can just read off the phase diagram for water (for the surface atmospheric pressure on each object). But could there possibly be some nuances that someone might miss just from viewing ...
-1
votes
1answer
455 views

Heisenberg's Uncertainty Forms

Can Heisenberg's Uncertainty principle be rewritten in terms of energy density writing $$\Delta E \Delta T \geqslant \hbar/2$$ in factors of energy density $\Delta \sigma \text{ }= \frac{3\Delta ...
4
votes
3answers
453 views

Why don't astronauts in orbit get stuck to the “ceiling”?

When a shuttle is in orbit, it is essentially rotating around the "centre" of the Earth at a great speed. So why does there seem to be no centrifugal force sticking them to the 'ceiling' of the ...
7
votes
3answers
6k views

How fast will the sun become a red giant?

I've read many accounts of our sun's distant fate, but what I've never heard is on what time scale these events occur. For instance, when the sun runs out of hydrogen, I presume it doesn't just WHAM! ...
3
votes
1answer
3k views

Entropy of two expanding and mixing ideal gases

I am currently stuck with the following problem: ...
6
votes
3answers
508 views

How does Hubble's constant affect the Earth's orbit

If Hubble's constant is $2.33 \times 10^{-18} \text{ s}^{-1}$ and the earth orbits the sun with average distance of 150 million kilometers; Does that mean the earth's orbital radius increases ...
2
votes
2answers
1k views

Which is the heaviest present day lifter (rocket)? And is it comparable to the Saturn V rocket?

I know of the Ariane 5 ECA, the Delta IV rocket and a few more, but which of the present day's rockets is the top heavy lifter, say, to low Earth orbit (LEO)? Although it is not a certain fact, I ...
2
votes
0answers
164 views

Are there formulae for calculating stellar luminosity and effective temperature as a function of age? [duplicate]

Possible Duplicate: Are there formulae for calculating stellar luminosity and effective temperature as a function of age? Is there a manageable formula or set of formulas or simple ...
40
votes
6answers
26k views

Why do power lines buzz?

When near high tension power lines, particularly after a good rain, the lines themselves emit a buzzing noise. A similar noise can be heard coming out of the electric meters attached to my apartment. ...
4
votes
2answers
379 views

Mixed state after measurement

I'm looking at Section 2.4.1 of Nielsen and Chuang's Quantum Computation and Quantum Information were they derive the density operator versions of the evolution and measurement postulates of quantum ...
5
votes
1answer
295 views

Why is UV index so high when storms are announced?

Everytime I check the weather news and storms are announced, the UV index is very often (if not always) "very high" or "extreme", why is that?
4
votes
2answers
1k views

On numerically solving the Schrödinger equation

I just read a paper 'A pocket calculator determination of energy eigenvalues' by J Killingbeck (1979). Link: http://iopscience.iop.org/0305-4470/10/6/001 I have some questions about section 2. Why ...
3
votes
2answers
427 views

The relativity of simultaneity

In his popular book on relativity, in chapter IX, "The relativity of simultaneity", Einstein describes an experiment in which a flash happens simultaneously on A and B, as defined by the fact that an ...
18
votes
6answers
2k views

Why can we treat quantum scattering problems as time-independent?

From what I remember in my undergraduate quantum mechanics class, we treated scattering of non-relativistic particles from a static potential like this: Solve the time-independent Schrodinger ...
-5
votes
1answer
807 views

Light Energy Absorption In Mirror

Let the amount of energy in one pulse of (laser) light be $E$, and the wavelength be $\lambda$. This pulse goes straight to the mirror, and it is reflected by the mirror. Let the reflectivity of ...
10
votes
3answers
3k views

Do eyeballs exhibit chromatic aberration?

Fairly straightforward question. If not, why not? I suspect that if they do, it is not perceived due to the regions of highest dispersion being in one's region of lowest visual acuity.
36
votes
8answers
34k views

Will a hole cut into a metal disk expand or shrink when the disc is heated?

Suppose you take a metal disc and cut a small, circular hole in the center. When you heat the whole thing, will the hole's diameter increase or decrease? and why?
6
votes
3answers
4k views

Why did the asteroid belt between Mars and Jupiter form as it did?

I'm curious about why the asteroid belt wasn't pulled by Mars's or Jupiter's gravity or formed into either moons or planets. Why did it form into an asteroid belt instead?
2
votes
2answers
445 views

Correlation functions in thermal field theory etc

Suppose I am studying a field theory at finite temperature or some black hole formation scenario from boundary theory perspective in the sense of AdS/CFT. How is it possible to gain information about ...
2
votes
0answers
190 views

Picture changing operators

What is a picture-changing operator in string theory? How do they work?
7
votes
1answer
334 views

Force curve associated with squeezing a worm-like chain (WLC) between two parallel plates

Let's say I have a polymer, of contour length $L_p$ and persistence length $P$, positioned between two parallel plates separated by a distance $z$. I slowly squeeze the plates together until only ...
0
votes
0answers
52 views

radioactive decay in molecular constituents [duplicate]

Possible Duplicate: What happens to chemical compunds that include radioactive nuclei, when those decay? Suppose a radioactive atom, which is incorporated in a molecule, decays? What ...
5
votes
2answers
811 views

What is meant by “combinatorial background” in experimental high energy physics

My guess is that they find a certain tracks coming from a certain source by "combintaorially" selecting all track pairs and finding their invariant mass. If this is true, of which I am not sure, how ...
2
votes
2answers
443 views

Are there formulae for calculating stellar luminosity and effective temperature as a function of age?

Is there a manageable formula or set of formulas or simple algorithms that approximate stellar luminosity and effective temperature (or radius) as a function of stellar age? I'm aware that accurate ...
6
votes
3answers
1k views

Are we capable of discovering planets in the Andromeda galaxy?

I just watched this SpaceRip video on YouTube which shows pictures taken by Hubble while looking into the disk of the Andromeda galaxy to study a certain type of variable star. It occurred to me that ...
3
votes
2answers
154 views

Could Jupiter's gravity destabilize Earth's artificial satellites over a long timescale?

Could Jupiter's gravity destabilize Earth's artificial satellites over a long timescale? After all, it can destabilize Mercury's orbit, and it can also destabilize orbits in the asteroid belt.
8
votes
4answers
6k views

How does a hole's size affect the distance that water will squirt

I took a bucket, drilled 2 different sized holes on the side near the bottom and filled it with water. The stream of water the proceeded from the larger hole traveled further than the stream from the ...
0
votes
2answers
161 views

Why only one prong in the plugs are not showing response to tester pen?

I have 2 pin outlet for A.C current . Now when I connect a TV plug in that and when I touch one of the prongs with my tester, the tester is showing response. But on the other prong the tester shows no ...
5
votes
1answer
134 views

What is the most convenient rocket engine to use exclusively in space?

I mean what parameters should a rocket engine that is used exclusively in space (last stage of a lunar rocket for instance) have?
8
votes
3answers
582 views

Why muonium is unstable?

This question is closely related to my previous question Bound states in QED. Muonium is a system of electron and anti-muon. This article in wikipedia claims that muonium is unstable. QUESTION: Why ...

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