6
votes
1answer
212 views
What happens to an embedded magnetic field when a black hole is formed from rotating charged dust?
Black holes have no-hair so there are uniquely specified by a mass, charge and angular momentum. Imagine a cloud of charged rotating dust. There will be a magnetic field associated with the current ...
6
votes
5answers
999 views
Recommendations for Statistical Mechanics book
I saw Book recommendations
No reference to Statistical Mechanics there.
I learned thermodynamics and the basics of statistical mechanics but I'd like to
sit through a good advanced book/books.
Mainly ...
6
votes
4answers
922 views
Shape of the universe?
What is the exact shape of the universe? I know of the balloon analogy, and the bread with raisins in it. These clarify some points, like how the universe can have no centre, and how it can expand ...
6
votes
3answers
3k views
Is Dr Quantum's Double Slit Experiment video scientifically accurate?
I'm fascinated by the fundamental questions raised by the Double Slit Experiment at the quantum level. I found this "Dr Quantum" video clip which seems like a great explanation. But is it ...
5
votes
2answers
771 views
Black hole analog experiment?
This question is directed mostly at people giving lectures on black holes, but input by other physicists or students is very much appreciated.
Do you know a good (home)-experiment with a black hole ...
3
votes
5answers
1k views
What differs string theory from philosophy or religion? [duplicate]
Possible Duplicate:
What experiment would disprove string theory?
A hypothesis without hard evidence sounds very much like philosophy or religion to me. All of them tries to establish a ...
2
votes
3answers
2k views
What is the math knowledge necessary for starting Quantum Mechanics?
Could someone experienced in the field tell me what the minimal math knowledge one must obtain in order to grasp the introductory Quantum Mechanics book/course?
I do have math knowledge but I must ...
20
votes
4answers
764 views
In quantum mechanics, given certain energy spectrum can one generate the corresponding potential?
A typical problem in quantum mechanics is to calculate the spectrum that corresponds to a given potential.
Is there a one to one correspondence between the potential and its spectrum?
If the ...
11
votes
4answers
677 views
Is the world $C^\infty$?
While it is quite common to use piecewise constant functions to describe reality, e.g. the optical properties of a layered system, or the Fermi–Dirac statistics at (the impossible to reach exactly) ...
8
votes
3answers
740 views
Hypercharge for U(1) in SU(2)xU(1) model
I understand that the fundamental representation of U(1) amounts to a multiplication by a phase factor, e.g. EM. I thought that when it is extended to higher dimensional representations, it would just ...
7
votes
3answers
2k views
When is the Hamiltonian of a system not equal to its total energy?
I thought the Hamiltonian was always equal to the total energy of a system but have read that this isn't always true. Is there an example of this and does the Hamiltonian have a physical ...
7
votes
3answers
873 views
Does a particle annihilate only with its antiparticle? If yes, why?
Or to put the question another way - what is the result of a proton-positron collision, or an up quark-charm antiquark collision, etc.? As far as I know, annihilation happens only between particles of ...
7
votes
4answers
1k views
Did time exist before the creation of matter in the universe?
Does time stretch all the way back for infinity or was there a point when time appears to start in the universe?
I remember reading long ago somewhere that according to one theory time began shortly ...
5
votes
4answers
505 views
Study Quantum Physics
I'm an aspiring physicist who wants to self study some Quantum Physics. My thirst for knowledge is unquenchable and I can not wait 2 more years until I get my first quantum physics class in ...
3
votes
2answers
574 views
Learn algebra and interpretation of QM
I have a good undergrad knowledge of quantum mechanics, and I'm interesting in reading up more about interpretation and in particular things related to how QM emerges algebrically from some reasonable ...
14
votes
1answer
2k views
Why can you see virtual images?
In optics it is widely mentioned real images are projectable onto screens whereas virtual ones can only be seen by a person. Isn't that contradictory? I mean in order to see the virtual image it has ...
13
votes
4answers
2k views
Why is the charge naming convention wrong?
I recently came to know about the Conventional Current vs. Electron Flow issue.
Doing some search I found that the reason for this is that Benjamin Franklin made a mistake when naming positive and ...
10
votes
4answers
753 views
Vortex in liquid collects particles in center
At xmas, I had a cup of tea with some debris at the bottom from the leaves. With less than an inch of tea left, I'd shake the cup to get a little vortex going, then stop shaking and watch it spin. ...
10
votes
5answers
667 views
8
votes
3answers
3k views
What's the difference between the five masses: inertial mass, gravitational mass, rest mass, invariant mass and relativistic mass?
I have learned in my physics classes about five different types of masses and I am confused about the differences between them.
What's the difference between the five masses:
inertial mass,
...
5
votes
7answers
989 views
What is the proof that the universal constants ($G$, $\hbar$, $\ldots$) are really constant in time and space?
Cavendish measured the gravitation constant $G$, but actually he measured that constant on the Earth. What’s the proof that the value of the gravitation constant if measured on Neptune would remain ...
5
votes
3answers
246 views
Is there a way to decrease the rate of nuclear Beta decay?
In that question and its answers it was mentioned that you could trigger radioactive decay by bombarding atoms with gamma rays of the right energy level (there may be other solutions I do not know ...
4
votes
3answers
245 views
Can we prove that the universe is finite or infinite?
If I say that the universe is finite, how can you say with certain that I am wrong?
4
votes
5answers
513 views
Time Dilation - How does it know which Frame of Reference to age slower?
Okay, I'm asking a question similar to this one here: Time Dilation - what happens when you bring the observers back together?. Specifically, I am curious about a specific angle on the second part of ...
4
votes
4answers
346 views
Chance of objects going against greater entropy
My book uses the argument that the multiplicities of a few macrostates in a macroscopic object take up an extraordinarily large share of all possible microstates, such that even over the entire ...
4
votes
1answer
645 views
Particle physics getting started
I know classical physics, quantum mechanics, special relativity, basic nuclear physics.
I would like to get into some particle physics.
I want to get into that higgs boson, lepton, quark things :D
...
3
votes
3answers
544 views
Why the heat flux vector at a point must be perpendicular to the temperature isothermal surface? Is it a definition or a deduction?
Before the question: I am working on numerical calculation of three dimension parabolic equation that based on Fourier's Law of which I am a little confused.
Here comes the law in modern mathematics ...
2
votes
2answers
1k views
Balloons and lifting gases
Hydrogen is the lightest element, so it's cable of lifting the most weight in out atmosphere (probably not the best terminology there, but you get the picture)
Would hot hydrogen (in the same sense ...
1
vote
0answers
76 views
Do particles travel backward and forward in time? [duplicate]
All these classical ideas are pointless and obsolete today, because in quantum mechanics, the particles are completely different objects, defined by quantum motion of fields, not by the location of ...
1
vote
1answer
369 views
Is all matter made of virtual particles?
This article in New Scientist says that all matter is actually virtual particles popping in and out of existence and nothing more. is this correct?
1
vote
2answers
162 views
What is the relativistic action of a massive particle?
all Lorentz observers watching a particle move will compute the same value for the quantity
$$ds^2 = -(c \, dt)^2 + dx^2 + dy^2 + dz^2,$$
$$ds^2 = g_{\mu\nu}dx^{\mu}dx^{\nu},$$
and ''ds/c'' is then ...
1
vote
3answers
874 views
Hours of light per day based on latitude/longitude formula
I'm looking for a formula that will return the number of hours per day given a specific location. I was thinking that can be calculated as a difference of sunrise and sunset, but I see that there are ...
10
votes
8answers
2k views
Is it possible to separate the poles of a magnet?
It might seem common sense that when we split a magnet we get 2 magnets with their own N-S poles. But somehow, I find it hard to accept this fact.(Which I now know is stated by Gauss's Law)
I have ...
9
votes
2answers
780 views
Invariant spacetime - distance - Circular Motion
I understand that the closer something travels to the speed of light, that time will stretch by a factor, and distance will compress by the same factor.
My question is, if something travels in a ...
8
votes
2answers
983 views
Proof that the One-Dimensional Simple Harmonic Oscillator is Non-Degenerate?
The standard treatment of the one-dimensional quantum simple harmonic oscillator (SHO) using the raising and lowering operators arrives at the countable basis of eigenstates $\{\vert n \rangle\}_{n = ...
7
votes
2answers
1k views
Tension in a curved charged wire (electrostatic force) - does wire thickness matter?
Consider a conducting wire bent in a circle (alternatively, a perfectly smooth metal ring) with a positive (or negative) electric charge on it. Technically, this shape constitutes a torus. Assume ...
6
votes
4answers
604 views
Help Me Gain an Intuitive Understanding of Lorentz Contraction
I'm having a hard time getting an intuitive understanding of Lorentz Contraction. I understand what it is by definition but I don't 'get it.' I'm not a physicist, just an amateur, so sorry if this ...
5
votes
3answers
3k views
Quantum entanglement faster than speed of light?
recently i was watching a video on quantum computing where the narrators describes that quantum entanglement information travels faster than light!
Is it really possible for anything to move faster ...
5
votes
3answers
446 views
How can a quasar be 29 billion light-years away from Earth if Big Bang happened only 13.8 billion years ago?
I was reading through the Wikipedia article on Quasars and came across the fact that the most distant Quasar is 29 Billion Light years. This is what the article exactly says
The highest redshift ...
5
votes
4answers
1k views
What is our location relative to the Big Bang?
Given what we know about space, time and the movement of galaxies, have we or can we determine what our position is in relation to the projected location of the Big Bang? I've read some introductory ...
3
votes
1answer
249 views
Reasons to suspect that matter is emitted from black holes nonthermally
Quote: "One has reasons to suspect that this matter is emitted from the black hole nonthermally, more or less as it came in, after doing a traversal of the interior regions." Ron Maimon in Do black ...
3
votes
4answers
362 views
Does $p=mc$ hold for photons?
Known that $E=hf$, $p=hf/c=h/\lambda$, then if $p=mc$, where $m$ is the (relativistic) mass, then $E=mc^2$ follows directly as an algebraic fact. Is this the case?
3
votes
2answers
287 views
More on matter and anti-matter
1.) Does every particle that has rest mass also have an anti-particle with which it would annihilate?
2.) Does annihilation only occur between like particles? For example what happens if a ...
2
votes
5answers
3k views
Mathematical background for Quantum Mechanics [duplicate]
What are some good sources to learn the mathematical background of Quantum Mechanics?
I am talking functional analysis, operator theory etc etc...
1
vote
1answer
242 views
Superluminal expansion of the early universe how is this possible?
Is this a postulate? I get the expansion of the universe, the addition of discrete bits of space time between me and a distant galaxy, until very distant parts of the universe are moving relative to ...
1
vote
1answer
185 views
What are the average matter, antimatter, and binding energy composition of protons and neutrons?
For a free baryon at rest at room temperature, how much of its ~1Gev (rest) mass can (on average) be considered as matter, as antimatter, and as binding energy?
For a baryon in a nucleus, I assume ...
36
votes
1answer
3k views
Why do we not have spin greater than 2?
It is commonly asserted that no consistent, interacting quantum field theory can be constructed with fields that have spin greater than 2 (possibly with some allusion to renormalization). I've also ...
26
votes
9answers
2k views
What is a field, really?
There was a reason why I constantly failed physics at school and university, and that reason was, apart from the fact I was immensely lazy, that I mentally refused to "believe" more advanced stuff ...
21
votes
9answers
2k views
Rigor in quantum field theory
Quantum field theory is a broad subject and has the reputation of using methods which are mathematically desiring. For example working with and subtracting infinities or the use of path integrals, ...
43
votes
6answers
4k views
What does it mean for two objects to “touch”?
If you've ever been annoyingly poked by a geek, you might be familiar with the semi-nerdy obnoxious response of
"I'm not actually touching you! The electrons in the atoms of my
skin are just ...
