3
votes
2answers
111 views

How can laser interferomerty be used to measure path difference smaller than wavelength of laser light?

The currently proposed Gravitational wave detection apparatus consists of Michelson Interferometer which is supposed to measure distances of the order of $10^{-22}$m. But the wavelength of the light ...
3
votes
0answers
33 views

Why charge density is higher in the sharp edges of conductor? [duplicate]

If we have a conductor which is in electrostatic equilibrium, then the charge distribution over this surface $\sigma$ is greatest at the sharp edges of that surface. Why is this the case? It is ...
0
votes
1answer
43 views

Electric field of a plate with homogenous charge density

As an example for Gauß Law's application, one can find the calculation of an electric field of a plate with homogenous charge density in nearly every textbook: $$E = \frac{\sigma}{2\epsilon_0}$$ I do ...
1
vote
1answer
79 views

Forces that fall under gravitational forces [on hold]

I was explaining the air motion in the atmosphere, so I introduced Gravity, Pressure Gradient and Coriolis Forces. Then one of the Professors asked me this question, which I couldn't answer. He said ...
0
votes
1answer
28 views

Will the current flow from the battery?

I am just trying to find out if the current enters into the positive terminal of the battery (if there is a battery with bigger emf ) will it get charged and charge will be stored and current will ...
3
votes
2answers
87 views

Why are vehicles not pitted like golf balls?

I have read that non-laminar flow reduces drag on blunt bodies. Given that, why is pitting not used on motor vehicles?
0
votes
2answers
31 views

Finding the Enthalpy of an Ideal Gas given internal energy

I am trying to find a formula for tying things up. Given an ideal gas like helium or nitrogen gas (diatomic) how can I find its enthalpy simply given internal energy? I remember it was once taught in ...
1
vote
1answer
13 views

Effects of vertical circular motion to the body weight

Our body weight will experience the differences when moving at constant speed in a vertical circular motion such as roller coaster. Why do we feel heavier when at the bottom of the loop and lighter ...
-1
votes
0answers
67 views

If the stress energy tensor $T=0$, does that mean $\delta{T}=0$? [on hold]

If the stress energy tensor $T=0$ in the vacuum, does that mean the variation of $T$ with respect to $g_{\mu\nu}$ equal zero? $$ \delta{T}=0 $$
2
votes
0answers
36 views

DOS integral when surface is not closed

According to the density of states (DOS) formula $$\rho(\varepsilon)\propto \int_{\varepsilon=\text{const}}\frac{dS}{|\nabla_k \varepsilon_k|}$$ Since there is an integral on the constant energy ...
0
votes
0answers
24 views

Are differences between elements besides the number of valence electrons negligible in forming matter and giving certain properties?

We were talking about life complexity, I don't know almost anything about physics, he told me that differences between elements beside the number of valence electrons are negligible and elements with ...
1
vote
0answers
20 views

DOS behavior of Van Hove singularity in a line

When there are some points in momentum space give $|\nabla_k \varepsilon_k|=0$, they are called Van Hove points and give singularity in the desity of states (DOS). But what if $|\nabla_k ...
1
vote
0answers
26 views

DOS of Van Hove singularity in 2D square lattice tight binding model

For the simplest example, 2D square lattice tight binding model gives the energy band as $$\varepsilon_k=-2t(\cos k_x+\cos k_y) \, .$$ We know that $\vec{k}=(0,\pi)$ and related momentum points are ...
1
vote
1answer
38 views

What causes continuous errors in a qubit?

I read that due to decoherence a qubit in a superpositon gets destroyed or put into one definite eigenstate. This kind of error seems to occur due to interactions with other stuff like the environment ...
0
votes
0answers
18 views

How to get DOS of Van Hove singularity using quadratic dispersion relation

Take 2D case for example. We can first get the area in momentum space for all $k$ that satisfy $E_0<E(k)<E $, say $S(E)$. And the density of state (DOS) is $\rho(E)=\frac{\partial S(E)}{\partial ...
0
votes
1answer
43 views

Changing linear to angular velocity

Suppose a 1m rod with a hook is travelling at v m/s, and the hook is caught on a hanging line. The rod will change its translational motion into rotation around the hook. Since it is not an elastic ...
-6
votes
0answers
27 views

Vector addition [on hold]

A pilot sets a course of 040$^{\circ}$ at an airspeed of $750$$km$$h^{-1}$. A wind blows SE at $140$$km$$h^{-1}$. Find the plane's ground speed and track. Can anyone illustrate this in a diagram?I ...
1
vote
1answer
94 views

Can I teach myself physics (LQG specifically)? [on hold]

OK I'm a second year undergrad student...have taken the introductory Math, Phys and Computer Science classes. I LOVE physics, and always have since I was a kid and wanted to major in that initially, ...
2
votes
1answer
91 views

Two math methods apply the same loop integral lead different results! Why?

I tried to adopt the cut-off regulator to calculate a simple one-loop Feynman diagram in $\phi^4$-theory with two different math tricks. But in the end, I got two different results and was wondering ...
0
votes
0answers
30 views

How to get the asymptotic expression of DOS near Van Hove singularity [duplicate]

For the simplest example, 2D square lattice tight binding model gives the energy band as $$\varepsilon_k=-2t(\cos k_x+\cos k_y) \, .$$ We know that $\vec{k}=(0,\pi)$ and related momentum points are ...
0
votes
1answer
30 views

current splitting in the presence of superconductors

When you have two resistors in parallel, the current splits up based on the resistances. What will happen if we have two superconductors in place of the resistors? What will happen to the current?
1
vote
0answers
31 views

Are we able to store low energy positrons in a magnetic field for arbitrarily long time? [on hold]

And if not, what prevents us? Is there a pattern describing the loss rate?
2
votes
1answer
27 views

Water well fluid dynamics

In my home village everyone has their own water well at the foot of the mountain (limestone) . The wells are over 100 feet deep but they are not cemented or have the area between the hole and the ...
-3
votes
2answers
79 views

“X-rays”, “gamma rays”, “sun rays”… But electromagnetic waves are NOT rays and DO NOT consist of rays?

In a separate question I'm struggling to figure out the nature of EM waves. But it's a vast topic and I'm trying to narrow it down to small specific questions. It turns out that all electromagnetic ...
0
votes
0answers
30 views

Is this a good explanation of electron mobility to the layman?

I'm writing an informative paper on graphene for my writing class (layman-oriented), and was describing electron mobility in very simplified terms. Let me know if anything is mistaken, badly ...
-4
votes
1answer
45 views

What is a safe viewing distance for nuclear fireworks? [on hold]

So people are setting off explosions and bragging about how big they are (fourth of july, you know), and I was wondering about setting off a big one. So lets say that the local firework show wanted to ...
3
votes
4answers
64 views

How does an inductor store magnetic energy?

I am trying to figure out what the potential energy of an inductor with a current really means. In a capacitor, the energy stored works like this: if you let the plates attract each other, before ...
0
votes
1answer
77 views

Is the wobbly rope depiction of a radio wave inherently wrong? And how do vectors of parallel waves align with each other?

I don't have a scientific education, yet I'm scientifically curious. Among other things, I'm struggling to understand the nature of electromagnetic waves. What I have recently realized is that the ...
-5
votes
0answers
26 views

Conseptual Questions on Optics [on hold]

a man of height h is standing in centre of a room in which a mirror is hanging to the opposite wall the height of the mirror required to see the full height of backside wall in the mirror is
0
votes
1answer
84 views

Work done in a capacitor with a conductor between its plates [on hold]

I have been agonizing over this problem, and have tried for more than two hours two find it with Kirchhoff equations, but I end up with 0=0 or some algebraic monstrosity. I have the following ...
0
votes
0answers
28 views

Can plasma in a Plasma ball be used as a source of true randomness?

This is just a thought but I've been staring at the Plasma Ball on my desk for a while and after a while I realized the plasma rays/waves/beams seem to be generated in a different spot each time so I ...
-8
votes
0answers
36 views

Is it possible to use electromagnetic waves to power an entire city [on hold]

I have a theory that it's possible to produce a huge amount of electric current through electromagnetic devices placed in four directions (N.S.E.W) with each facing the opposite side and an amplifier ...
0
votes
3answers
62 views

How much force does it take to move the Earth? [on hold]

If you could fly and survive in space, how much force would you need to move Earth at 1 meter per second?
-3
votes
0answers
44 views

Thermal contact burn [on hold]

My client fell asleep in a bus stop leaning back against 3/16 in clear plate glass For an hour with a tee shirt on. It was about 80 degrees Fahrenheit and the sun was shinning on the glass. He woke up ...
-3
votes
0answers
44 views

How does the Universe connect with other Dimensions? [duplicate]

I was wondering that if the Universe was expanding, what was it expanding into. I came up with a theory and I was wondering if there was any information to support my theory, if my theory is wrong ...
1
vote
0answers
50 views

How does the Higgs field relate to the Yang-Mills fields and gauge theories in general?

I asked this in astronomy How does the Higgs field relate to the Yang-Mills fields and gauge theories in general? but they suggested I ask it here. It is very confusing. Is there an easy ...
1
vote
1answer
48 views

Why didn't we have inflation when the theory of everything and GUTS broke symmetry?

I asked this in astronomy and they suggested I ask it here. Inflation seems to have occurred when the symmetry breaking of the electroweak occurred. But do we know of any reason why we did not have ...
1
vote
1answer
63 views

Does the Heisenberg uncertainty principle preclude moving in a straight path with certainty?

The uncertainty principle is σₓσₚ ≥ 0.5 ℏ where x is position and p is momentum. Consider a 2d plane. If one moves along a straight line along the plane (possibly backtracking or moving forwards but ...
0
votes
1answer
131 views

Does gravitational field has gravitational mass?

Other questions closely related to the one of the title (as I will show) are Does speak about work done on photon has sense? Does photon has a gravitational mass? Does exists a modern (and more ...
0
votes
0answers
32 views

What am I missing in this reasoning?

In studying the problem of locomotion at low Reynolds number, one possible approach is based on gauge theories. In simple terms, one considers a sequence of shapes of a certain deformable body, say ...
-3
votes
2answers
41 views

Doubt on resistor circuit [on hold]

How are we able to flip the triangular resistor to the opposite breaking its connection with the lower 2r resistor?
2
votes
0answers
26 views

Reverse recovery current + diode

The reverse recovery current of a diode is due to accumulated charges in the P and N region during it forward stat. I want to know this current is a diffusion current or a drift current?
-2
votes
1answer
87 views

Will the age of the universe gets longer, even if time doesn't flow anymore? [on hold]

To start off, I would like to define a clearer definition of time: Time (in italic): a dimension of the universe. This is equivalent to space. Time (in plain): a number measured by second. Age = ...
0
votes
2answers
33 views

Rapid/ Slow Expansion in Gases

How is rapid expansion of gases different from slow expansion?
0
votes
1answer
47 views

Wavelength of light too long to measure electron position in double-slit experiment?

I'm a mathematician, so I am not familiar with experimental physics. I am watching MIT course on Quantum Mechanics, and they describe the two-slit experiment with electrons passing through the slits. ...
-5
votes
3answers
94 views

Can pure mathematics alone give proofs in science [on hold]

I reasoned in my last post that because of science's nature of induction and falsifiability, it is impossible to give a theorem in science, unlike in mathematics. It is because even when a scientific ...
0
votes
0answers
24 views

Can I measure the volume of a locked room by pumping gas through keyhole and measuring its entropy?

Suppose that I have a locked room and a keyhole in the door and I want to measure the room's volume. Suppose also that I have some "magical" "artificial" inert gas A that doesn't interact with ...
2
votes
2answers
87 views

Is the stress energy tensor continuous at the interface between an object and vacuum?

The stress energy tensor has (as I understand) zero value in the region where there is no matter and non-zero value where there is matter. Suppose there is one matter object in space, now how does the ...
1
vote
4answers
83 views

Why is the definition of mass and matter interlinked?

In my textbook the definition of matter and mass are: Matter: Any thing that occupies space and has mass . Mass: The amount of matter contained in a body. While defining "matter" we refer to ...
-5
votes
0answers
40 views

Quantization of electric charges [on hold]

As per charge quantization of charge $Q=ne \Rightarrow n=Q/e$. But there can exist some charge $Q$ such that $n$ isn't an integer (i.e if $Q/e$ is repeating or recurring decimal). This can prove ...

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