# All Questions

552 views

### Is there a different behavior between proton and antiproton beams at the Tevatron?

This question has its origin to the reference on the Aegis experiment at CERN where they aim to produce super cooled antihydrogen and detect whether its reaction to gravity is negative. It set me ...
387 views

### If : V(Phi) : is nonlocal in space, does that mean interacting quantum field theory is nonlocal?

Free field theories are definitely local in . In the interaction picture, we can decompose the fields into creation operator modes and annihilation operator modes. The product of operators can be ...
769 views

### Dual conformal symmetry and spin networks in ABJM

In this question, I would love to hear some independent opinions on an issue I asked Juan Maldacena, Nathan Berkovits, Dan Jafferis, and others, but all the physicists may be missing something. The ...
5k views

### How to learn physics effectively and efficiently [closed]

How do you effectively study physics? How does one read a physics book instead or just staring at it for hours? (Apologies in advance if the question is ill-posed or too subjective in its current ...
316 views

### Information about an expanding event horizon

Assume an observer sent a beam of photons close to an event horizon, say at some distance x (a distance far enough to avoid the photons falling in.) This light would still be observable, albeit red ...
399 views

### NASCAR drafting at Daytona

This year, the racetrack at Daytona has been repaved. The track was always faster than other tracks NASCAR raced at and several cars in a "train" were faster than single cars or smaller trains. This ...
3k views

### What does it take to become a top physicist? [closed]

What does it take to become a top physicist? Why do so many extremely talented young upstarts totally flop as they move to more advanced physics?
337 views

### Are strange metals described by a quantum critical theory?

Are strange metals described by a quantum critical theory?
472 views

### Astronomical detection significance from magnitude error

At this website: http://heasarc.gsfc.nasa.gov/docs/swift/analysis/threads/uvot_thread_afterglows.html The passage at the bottom states that a V-band magnitude of 17.62, with an error $\pm$0.02 is a ...
167 views

### Would it be worthwhile to work out a manifestly supersymmetric superspace formalism for 16 and 32 real SUSY generators?

For 4 real SUSY generators, the superspace formalism has been worked out a long time ago. For 8 real SUSY generators, some brilliant theoreticians have worked out the details of harmonic superspace. ...
3k views

### Is Mach's Principle Wrong?

This question was prompted by another question about a paper by Woodward (not mine). IMO Mach's principle is very problematic (?wrong) thinking. Mach was obviously influenced by Leibniz. Empty space ...
485 views

### Supersymmetry breaking and Goldstino

I would be glad if someone can explain to me the argument as to why supersymmetry breaking is necessarily accompanied by appearance of a massless fermion, namely the goldstino. (and also why this is a ...
2k views

### Is the Woodward effect real?

Did anyone ever heard about this?I've never seen any serious physicist talk about "mass fluctuations". Here is the man in his own words: http://www.intalek.com/Index/Projects/Research/woodward1.pdf ...
747 views

### What does the fine structure constant describe?

Feynman says in his book "QED" that the square root of the fine structure constant is the probability for a charged particle to emit a photon. But for which wavelength? Or is it an average over all ...
1k views

### Why do particles move? [closed]

Is all particles moving and forever? Can the movement of particles be stoped ?
489 views

### Does the potential energy for a given photon increase or decrease in quanta?

As a photon leaves a strong gravitational field, it loses energy and redshifts. Is the exchange in potential energy of a photon characterized by energy quanta?
5k views

### The speed of gravity?

Sorry for the layman question, but it's not my field. Suppose this thought experiment is performed. Light takes 8 minutes to go from the surface of the Sun to Earth. Imagine the Sun is suddenly ...
836 views

### What is physical in the principle of local gauge invariance? [closed]

Modern theories of interactions in particle physics are gauge ones. I know how the gauge fields are introduced in equations ($D = \partial + A$). I just do not see any physical motivation in it. I am ...
399 views

### Body's Electrical Resistance

I am not someone specialized on physics, I am just curious on why our Body Electrical Resistance measure as shown by a multimeter varies so much. When allocating the 2 probes each on one hand, the ...
2k views

### Why is the bispectrum not commonly used in experimental physics?

Power spectra, coherence spectra, and linear transfer functions are ubiquitous tools of experimental physics. However, our instruments often retain small nonlinear effects which can contaminate ...
385 views

### On-site repulsion and Pauli exclusion

Been studying hopping conduction and something that everyone is taking for granted is bothering me. Let's say we have a bunch of sites that are either unoccupied, singly occupied, or doubly occupied. ...
210 views

### Internal Energy Terminology

I am interested in finding out whether the term 'Internal Energy' can be used in both of the following cases: In the case of a macroscopic body upon which light is incident, the internal energy ...
14k views

### Explanation for different boiling points of water on different altitudes

I understand water boils at different temperatures depending on altitude. I am seeking to get an illustrative explanation for this, including a diagram if possible.
3k views

### How does an altimeter work?

In our aerodynamics class we recently discussed the concept of static and dynamic pressure and discussed their application to aircraft instruments. However, I do not understand properly how the ...
11k views

### What is the difference between a moment and a couple?

In mechanical engineering, the torque due to a couple is given by $\tau = P\times d$, where $\tau$ is the resulting couple, $P~$ is one of the force vectors in the couple and $d$ is the arm of the ...
366 views

### How does solar activity affect the ISS?

Currently the sun is launching some intense solar flares. http://www.guardian.co.uk/science/2011/feb/17/solar-flares-northern-lights-uk Th article I've linked also mentions how a "coronal mass ...
499 views

### Viscosity/Entropy ratio and unitary evolution in quantum gravity

Calculations of the shear viscosity of the quark-gluon plasma (QGP), observed in heavy ions collisions, are performed via the AdS/CFT correspondence [ref1]. One finds that the shear viscosity of the ...
806 views

### Quantum numbers of the helicity states of the W boson

What are the weak hypercharge and weak isospin quantum numbers of the helicity states of the $W^\pm$ and $Z^0$ bosons? The W boson is a spin-1 massless particle. Consequently it has three helicity ...
2k views

### List of theories supporting origin of universe [closed]

Big Bang theory is widely accepted theory when it comes to origin of universe. What other really compelling theories are out there explaining/supporting the origin of universe. I know many people ...
154 views

### Meaning and types of singularity in case of string or any cosmological model (Mathematical description)

What is actual meaning of singularity can we use this term for conclusion in any research paper( related to cosmological models ).what r the types .
741 views

### converting force from spherical to Cartesian coords

So I am working on my assignment, and have a question about converting coordinates. I dont know whether I should ask here or the math SE, so lets give it a try here. The force in question is ...
318 views

### Angular momentum

I'm given with the following problem - it's an easy one, but it's nearly 1AM, I'm tired and I need some push into the general direction to get the solution: A particle is assumed to be in the state ...
148 views

### Quickest “flights” across Atlantic and round the world

With the dawning of the private space industry, if someone was to build a rocket-based craft that powers you up and then glides in for a landing, what would be the quickest you could get across the ...
383 views

### Quantum death like heat death possible?

Quantum decoherence is an irreversible process which is the result of interaction of the system with its environment. It prevents interference due to lack of coherence. Environment acts just like a ...
701 views

### Why isn't pressure a measure of energy?

Hey guys, I'm having a problem in understanding the 1st Law of Thermodynamics. If i would increase the pressure of a closed system by compressing a gas in a cylinder isothermal, the 1.Law states, ...
347 views

### Making and keeping a reading list

Seeing this as an academic community, I hope this question is on-topic. Academia is still a long way from beta :( I have a few questions about reading journal ...
2k views

### Symmetric potential and the commutator of parity and hamiltonian

In one dimension - How can one prove that the Hammiltonian and the parity operator commute in the case where the potential is symmetric (an even function)? i.e. that [H, P] = 0 for V(x)=V(-x)
269 views

### Why should the mass of leptons to be near of proton and QCD/chiral scales?

The mistery of the mass of the top being in the electroweak scale can be justified by the Higgs mechanism itself; in some sense the top mass is the only "natural" mass, the other masses of fermions ...
224 views

### Soft Condensed Matter

I need a book dealing in particular with the intermolecular forces and, if possible, the diffusive processes. Someone knows an appropriate one?
6k views

### Weight on carpet vs. hard floor

Will the scale say I weigh more, less, or the same on a carpet as compared to a hard floor? You can assume the scale works via spring mechanism. Free body diagrams encouraged!
2k views

### Why an object travels a circular path?

It might sound stupid but seriously I couldn't find why? We have a mass with a constant speed, which is acted on by a unit force which is always at right angles to its direction of motion. Why do ...
202 views

### Are there string backgrounds which can't be described by first quantized string theory?

In the strong coupling limit of type IIA and heterotic E8 string theory, we get 11 dimensional M-theory in which we have no strings. Instead, we have M2 branes. Are there any other backgrounds in ...
176 views

### Is string theory over a time varying background a conformal field theory to all orders in perturbation theory?

When computing the first order perturbative corrections to string theory over a curved background, we find the background has to be Ricci-flat if the dilaton is constant and we have no fluxes. Such is ...
980 views

### Why is high temperature superconductivity so hard to solve?

The phenomenon of high temperature superconductivity has been known for decades, particularly layered cuprate superconductors. We know the precise lattice structure of the materials. We know the band ...
219 views

### Is there any way to distinguish experimentally gauge mediation from gravity mediation in an unambiguous way?

There are lots of models of gravity mediated SUSY breaking with various spectra as well as various general gauge mediation models. Are there any "smoking gun" experimental singnatures that could ...
1k views

### What does Lijun Wang's experiment about supraluminal speed of light in a medium mean?

This is a summary from Physics World of the paper: L J Wang et al. 2000 Nature 406 277-- "Wang and colleagues begin by using a third continuous-wave laser to confirm that there are two peaks in the ...
1k views

### Maximum size of the observable universe?

The size of our observable universe must have grown over time in the early universe. Conversely with the accelerated expansion, I have heard that eventually our observable universe will shrink down ...
851 views

### Dirac equation on general geometries?

I have a numerical method for computing solutions to the Dirac equation for a spin 1/2 particle constrained to an arbitrary surface and am interested in finding applications where the configuration ...