All Questions

296 views

Extended Rigid Bodies in Special Relativity

I was reading Landau & Lifhsitz's Classical Field Theory and I noticed that they mention that an extended rigid body isn't "relativistically correct". For example, if you consider a rigid rod ...
1k views

Can you completely explain acceleration to me?

I understand what acceleration is, and I know the formula, and I understand it's a vector. I just don't understand how the equation works exactly. I'm kind of picky, I know, but bear with me. ...
90 views

Is there real materials have Lieb lattice structure? [closed]

Is there real materials have Lieb lattice structure? Some examples?
259 views

How to find angular velocity of a point inner a circumference

Let's consider a cicumference that have the center in the origin of axes and rotates around x-axes. Let's stick a bar in a point $A$ of this circumference and at the end of the bar let's stick a mass ...
208 views

Why do air bubbles stick to the side of plastic tubing?

I'm watching water with air bubbles flow through transparent plastic tubing. The inner diameter is a few mm. Bubbles typically are the same diameter as the tubing, with length about the same or up ...
1k views

Connection between quantum physics and consciousness

Can someone explain the quantum physics-consciousness connection? In the double slit or quantum eraser experiments, the system behaves as a whole, with some apparent time independent traits. Invoking ...
245 views

Nuclear Salt Water Rockets: viability and follow-up

This is the original paper by R. Zubrin proposing the Nuclear Salt Water Rocket design. Basically the design is that a capillar set of pipes store a uranium salt-water solution, inside a cadmium ...
337 views

Eigenvalues of a quantum field?

Fields in classical mechanics are observables. For example, I can measure the value of the electric field at some (x,t). In quantum field theory, the classical field is promoted to an operator-valued ...
1k views

Is time speeding up due to the expansion of space?

If we just look at our local galactic cluster, if all of the galaxies that are a part of it are moving away from each other, and so the overall 'density' of the strength of gravity in the cluster is ...
226 views

Can endergonic reactions occur outside of living organisms?

If the Gibbs free energy equation is defined as: ∆G = ∆H - T∆S And the amount of energy/work released from a reaction is: ...
119 views

Equivilence of One Flux Quantum and Zero Flux

In Ady Stern's review of the Quantum Hall effect, he says of a quantum hall system "The spectrum at $\Phi = \Phi_0$ is the same as the spectrum at $\Phi = 0$..." Can someone explain why this is? It ...
282 views

The physicality of the photon propagator

The equation for the photon propagator is straightforward $$D_{ij} = \langle 0 |T \{ A_{i}(x')A_{j}(x) \}|0 \rangle$$ However, $A_{i}(x)$ is gauge-dependent and therefore unphysical (in the arguable ...
170 views

Determine date of birth from “astrological” signs?

Suppose someone tells me what constellation the Sun, Moon, Mercury, Venus, Mars, Jupiter, and Saturn were in when they were born, and the information is astronomically accurate (ie, not astrological ...
189 views

Integral in Peskin and Schroeder

I'm having a bit of a slow day, and can't see how to do the following integral in Peskin and Schroeder (page 107 for anyone with the book). We've derived in the centre of mass frame the integral over ...
278 views

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Intervals as infinitesimals of same order (Landau & Lifshitz)

I don't understand the following statement in Landau & Lifshitz, Classical Theory of Fields, p.5: $ds$ and $ds'$ are infinitesimals of same order. [...] It follows that $ds^2$ and $ds'^2$ must ...
299 views

What are thermal energy distributions?

I am trying to understand the photoelectric-effect deeply. My teacher used the Planck's law and integrated it to deduce the Stefan-Boltzmann law. He somehow showed some quantum-physical ...
61 views

the poles of impurity system's Green's function

Denote the pure system as system 1, with both continuum and discrete eigen energy. $G_0$ is its Green's function. After introducing some impurities, we call the resultant system system 2 with new ...
469 views

Noether theorem and classical proof of electric charge conservation

How to prove conservation of electric charge using Noether's theorem according to classical (non-quantum) mechanics? I know the proof based on using Klein–Gordon field, but that derivation use ...
122 views

Calculating the $\frac{dp}{dT}$ slope using Clausis-Clapeyron

I've produced experimental data over how the boiling point of water varies with pressure and temperature and plotted this in a PT graph. I would like to verify my results using theory. The ...
171 views

How can gas from compressed air can “take” heat from surrounding environment?

I have recently been reading about why a can of compressed air gets cold when the air it contains is discharged. From what I understand the change from a liquid to a gas requires energy and therefore ...
213 views

How to calculate the effect of the earth's magnetic field on a HZE particle?

I'm trying to calculate the protection provided by the earth's magnetic field from HZE particles to astronauts in low earth orbit, such as those on the ISS. HZE particles are often quoted as a danger ...
94 views

Deriving term symbols from electron configuration using Young tableaux

Can somebody explain me how to derive all term symbols using Young tableaux? Our lecturer showed us but I couldn't quite understand it without any background on group theory. I have some vague ...
319 views

Do we exert more force when we walk?

When we walk, is the magnitude of the earth's force on us greater than if we were standing still?
420 views

Temperature below absolute zero?

I saw this Nature article today, which cites e.g. arXiv:1211.0545. And it makes no sense to me. The temperature of a collection of particles is the average kinetic energy of those particles. Kinetic ...
78 views

Understanding a sagnac interferometer with the half-silvered mirror reversed

I've been trying to make a simple puzzle game based on quantum optical circuits. Problem is, I don't actually know the physics that well (this is a hobby project with the goal of increasing that ...
925 views

Earth moves how much under my feet when I jump?

If I'm standing at the equator, jump, and land 1 second later, the Earth does NOT move 1000mph (or .28 miles per second) relative to me, since my velocity while jumping is also 1000mph. However, ...
641 views

Is there some way to narrow down the Leidenfrost point for water?

Cooks sometimes use the Leidenfrost effect to estimate the temperature of a frying pan by flicking a few drops of water onto the heated pan. I had no idea, before looking into this, that this could be ...
130 views

Why is a washing machine unable to spin-dry a duvet?

Background story: I put my duvet (synthetic filling) into a washing machine, and the machine was unable to spin-dry it. My mom told me: "It's because it is full of air". I was not satisfied with the ...
619 views

How much information about the scale of a waterfall can be obtained from its sound?

Is it possible to constrain the height, volume flow, or distance of a waterfall from the quantitative analysis of a high-quality recording of its sound? As an aside, the simulated sounds of fluid ...
I have the following situation: About the polarization of the photon, I introduce the basis: Horizontal polarization $|\leftrightarrow>=\binom{1}{0}$ Vertical polarization ...