Physics Weekly Newsletter
Physics Weekly Newsletter

Top new questions this week:

If we threw a baseball from the ISS, could we deorbit the ball?

Clearly this is a hypothetical question. Say we bring a star baseball player into NASA, prep them appropriately for a mission in space, and fly them up to the International Space Station. They go on ...

newtonian-mechanics newtonian-gravity orbital-motion vacuum drag  
asked by Martin Carney 24 votes
answered by John Rennie 31 votes

The scope of physics, as taught in modern times

I am asking this question based on my recent experience as a physics major at a well-known school of science and engineering. My basic question is, Why does the field of physics (at least at an ...

soft-question education  
asked by Merkh 19 votes
answered by Floris 23 votes

Same photon or different photon?

Consider a typical optical focusing system: A small light source, then a collimating lens, then a focussing lens, and then a detector (e.g. CCD). Assume that source intensity is so low that only one ...

quantum-mechanics optics electromagnetic-radiation photons identical-particles  
asked by atom 17 votes
answered by anna v 18 votes

Is the existence of a sole particle in an hypothetical infinite empty space explicitly forbidden by QM?

Suppose the universe is completely empty with one sole particle trapped in it. To simplify, I will only be looking at the one dimensional case. However, all arguments are applicable for three ...

quantum-mechanics hilbert-space schroedinger-equation approximations  
asked by Mark 15 votes
answered by ACuriousMind 21 votes

Light's inverse square law: Does it require a minimum distance from the source?

Does the inverse square law begin to take effect the moment light leaves its source? For example, does light's intensity decrease, i.e. does the area in which the photons might land increase, at a few ...

quantum-mechanics classical-mechanics optics visible-light electromagnetic-radiation  
asked by David Reishi 10 votes
answered by Cort Ammon 14 votes

Which formula for the de Broglie wavelength of an electron is correct?

So, I have my exams in physics in a week, and upon reviewing I was confused by the explanation of de Broglie wavelength of electrons in my book. Firstly, they stated that the equation was: $\lambda = ...

waves electrons diffraction matter  
asked by Kasper 8 votes
answered by DarthPlagueis 8 votes

How can dimensional regularization "analytically continue" from a discrete set?

The procedure of dimensional regularization for UV-divergent integrals is generally described as first evaluating the integral in dimensions low enough for it to converge, then "analytically ...

quantum-field-theory renormalization dimensions analyticity dimensional-reg  
asked by tparker 7 votes
answered by yuggib 1 vote

Greatest hits from previous weeks:

Linear acceleration vs angular acceleration equation

I'm learning about angular velocity, momentum, etc. and how all the equations are parallel to linear equations such as velocity or momentum. However, I'm having trouble comparing angular acceleration ...

rotational-dynamics vectors angular-velocity  
asked by Griffin 4 votes
answered by Bernhard Heijstek 7 votes

What exactly is the difference between advection and convection?

After reading Wikipedia articles on advection and convection, I still cannot determine whether there is a consensus on a difference between these two terms. Sometimes, the term convection seems to ...

fluid-dynamics heat terminology convection  
asked by Wok 19 votes
answered by John Rennie 8 votes

Can you answer these?

Uncertainty principle and digital camera

I recently got into a discussion in how far (miniaturized) digital cameras are affected by the uncertainty principle. Specifically the question was, whether the uncertainty principle is one of the ...

asked by dliw 1 vote

What are the Higgs masses for $SU(2) \times U(1)$ goes to $U(1)$ symmetry breaking with a complex triplet?

Consider an $SU(2)\times U(1)_Y\rightarrow U(1)_{EM}$ theory that is broken via a complex triplet with hypercharge 2. The potential is of the form \begin{align} V(\Phi) = -m^2\Phi^\dagger\Phi + ...

homework-and-exercises quantum-field-theory mass symmetry-breaking higgs  
asked by jeau_von_shrau 1 vote

Rainbow Black Hole

In the photon sphere of a black hole the photons are being trapped in orbit, pulled in and trajectories changed. Should we see color of the entire spectrum in the photon sphere? That a black hole ...

visible-light black-holes photons mass-energy  
asked by Jen 1 vote
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