# All Questions

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### Relativistic Doppler Effect and the Sagnac effect

What I think I know about the Sagnac effect can be found here. It occurs to me that the equations for calculating the time do not take the Doppler effect into account. I'm familiar with the very ...
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### What is the role of exotic hadrons in particle physics? [on hold]

As the title! I like lots of detail. Thanks folks! EDIT: As user23873 brought to my attention, I am referring to tetra/penta quarks and others like those recently discovered at CERN.
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### How do we 'watch ' atomic interactions?

I'm relatively new to objective physics and it's measuring and imaging abilities.. Specifically I don't know if we can 'watch' inter/or intra molecular exchanges like the photonic and electronic. I ...
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### How to see the ground state degeneracy (GSD) from a $BF$ theory in $2+1$ $d$?

I have seen many times the $BF$ theory has non-trivial ground state degeneracy (typically on torus), but I can not see how the conclusion come out. Recently I found a paper by Hansson, Oganesyan and ...
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### Circuit Diagram [on hold]

Three resistor are put into play, two in parallel and another in series to them. One of the resistors in parallel is decreased. what will happen to the voltage and current.
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### How can light have the same speed for all observers? [duplicate]

I'm a little confused on this. If you're travelling at, say, 10% of the speed of light then light is travelling at 3x10^8 ms^(-1) relative to you. If you're moving at 80% of the speed of light and ...
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### Interaction Lagrangian forms

When a charge motion is given (known), the electromagnetic field can be explicitly found (Retarded potentials, etc.). The interaction Lagrangian density is $j\cdot A$ or in the action it may look like ...
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### Theory on what would happen if a proton touches anouther [on hold]

I came up with a theory on what would happen if two protons touched each other. I want to know if it is scientifically valid. If two protons repel each other, then the closer you bring them together, ...
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### Electric Field due to volume charge [on hold]

Electric Field at point P due to volume charge Since,the Electric field at point (0,0,z) is dE = ρvdvaR/4πε0R2 aR = cosα az + sinα aρ where aR means unit vector R can anyone derive the above ...
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### Dry Ice Sublimation time, practical calculations [on hold]

I would like to send a parcel to a family abroad with frozen (to the temperature of -18 ° C.) products.The products are small balls having a diameter of 4 cm. Balls are made from pizza dough.Total ...
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### Why do we believe in a “force” driven universe? [on hold]

Why do we not believe in the potential for a "unified force field" universe, to the exclusion of the belief in the potential for a mechanical, gear driven universe, if the correct shape for the gear ...
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### Is Ballentine's description of the Berry phase (in his book _Quantum Mechanics_) flawed?

Ok, so I'm looking at Ballentine's Quantum Mechanics right now, 7th reprint (2010). On page 363, he starts with 12.7 Adiabatic Approximation and quickly moves on to explain Berry's phase on page 365. ...
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### Why charge is an extensive property [duplicate]

While reading examples of extensive properties, I cam across electric charge. Can someone please explain to me why electric charge is considered to be an extensive property? We know that extensive ...
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### Which inertial observer should I choose when using $\Delta U = -\Delta K$?

I just read and undertood that For any conservative force $F$ (which is not necessarily constant), we can define a potential energy change $\Delta U$ of an object on which the force exerts as ...
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### What is the Weak force?

In this Particle Physics books I'm reading it explains Weak force with Beta Decay, a Neutron turns into a Proton after emitting an electron, so after it emits an electron one of the neutrons ...
### What does it mean by $t=-1$?
if the position vector of a particle is $\hat{r}=\left(4+3t\right)\hat{\imath}+\left(t^3\right)\hat{\jmath}+\left(-5t\right)\hat{k}$, i want to find at what time this particle passes through the point ...