are electric field and magnetic field the same thing under different perspectives? why do we identify the electric force and the magnetic force as one electromagnetic force?
I'm tutoring high school students. I've always taught them that:
A charged particle moving without acceleration produces an electric as well as a magnetic field.
It produces an electric field because it's a charge particle. But when it is at rest, it doesn't produce a magnetic field. All of...
The Lorentz transform takes you between frames moving with respect to each other. I've only really done them for constant velocity changes, but apparently you can handle acceleration within SR. I don't know if I would say that EM and SR are fundamentally linked together. You need SR to get EM correct and I think we discovered SR through EM, but I don't believe that SR requires EM to exist.
I don't know what your experience level is, but two quite informative exercises I've done are the above about moving an infinite line charge and looking at a beam of light that goes from A to a mirror at B then back to A both at rest and moving with constant velocity in a direction perpendicular to the beam.
Purcell is the only place that I've seen a discussion of the transformation of fields without the introduction of the field tensor, but I've personally not been able to gain much from that book.
caused certainly isn't the way that I'd put it, but I'm no expert
You'd have to look through his answers. One of them is actually what I was alluding to regarding acceleration in SR, but I'm not sure what else there is
I don't know if it is because of my latest question on main or because of all good help I am getting. can someone tell me if there is a reason I get more faster as I obtain more?
@PeterShor if the information is "still there", it would mean that a hidden variable interpretation of the physics would be possible. That is and has been a large discussion subject in physics. — fishinear7 hours ago
oh, new users. Showing their deep understanding of the current state of the discussion in physics, and unafraid to tell other people about it.
@EmilioPisanty lol. Maybe the OP doesn't realise that that's the Peter Shor. :) I'm not implying that we should bow down to authorities, just that it's wise to assume that they probably know what they're talking about, especially in discussions related to their field of expertise
user301074
rdm question; What's specifically is an spacetime with non-trivial topology?
user301074
i've read that is an spacetime which is not simply-connected
The Problem
I was going to write a question here asking what the appropriate response is to incorrect upvoted answers, but I realized that I'm far from the first person to ask this, e.g.
How should we deal with upvoted incorrect answers?
Are technically wrong answers and comments allowed on ph...
@LeakyNun the Lorentz covariant object is called the field strength tensor. This is generally written as a 4x4 matrix and the elements of the matrix give you the values of the electric and magnetic fields.
However to write down the components of the matrix requires you to choose a system of coordinates, and the values of the elements then depend on what coordinates you choose.
So while the field strength tensor is a covariant object, the electric and magnetic fields you observe depend on your coordinates so they are changed by Lorentz boosts. In effect the electric and magnetic fields are views of the tensor and the view changes depending on where you are looking from.
@CaptainBohemian if there is any region where humans live that is free from superstition and inequality I have never heard of it. Though I'll concede that some areas are more superstitious and unequal than others.
The problem with snow in the UK is that on the roads it quickly melts to an evil black mixture of slush and road dirt. Then if I cycle into town I, my rucksack and my pushbike get spattered with drops of the unholy stuff.
so when light goes from a denser medium to a less denser medium at grazing angle, if you increase the angle of incidence anymore the light will reflect. Well, why does it reflect back?
why doesn't it just come back i to the same medium at another grazing angle?
why does it make that jump and come back at the angle of incidence? Why not come back at some really small angle if we are talking about refraction..
It's probably best to chat here if you're going to ask about QM as my grasp of the fundamentals isn't actually that deep. There will be other members of this chat who know far more about QM than me.
The only significant benefit to asking me is that because my own knowledge isn't so good I tend to look for simple explanations :-)
@JohnRennie I created a room (mostly to see how you do it) just in case it gets busy in here and we want to discuss more, or if we have conflicting schedules
@JohnRennie not really, first 7 or so lectures don’t go very far in terms of depth
I live in Liverpool, and my girlfriend lives in Chester so I’m down there all the time!! We’ll have to meet up for a coffee some time and talk some ohysics
@CaptainBohemian Wild guess: people on the "shortlist" will get offered fellowships first. If some of them accept offers elsewhere and money/positions remain, offers will extended to people on the "reserve list."
@rob It turns out there is no standard usage of "reserve list" and "shortlist"--their usage varies with the administers. I considered there is. I originally guessed "shortlist" means "applicants who filfill all the requirements of the fellowship but may not be admitted due to the great number of applicants who filfill the requirements. But now I see the new term "reserve list", so I wonder the difference between them.
In job interviews there are typically three rounds of cuts. First comes the culling of most of the resumes that are submitted, to eliminate e.g. the resumes which have been written in crayon. Second is a set of low-stakes interviews, possibly over the telephone, with a large-ish number of candidates. Third is a set of on-site, in-person interviews with a smaller number of people. One of those gets offered the position.
The folks who are invited to interview on-site are typically referred to as the "short list."
For a PhD fellowship (which is really just a weird kind of a job) you have multiple positions open at the same time, so there's a risk that not everyone on your short list will be prepared to accept an offer if you make one.
In that case, offers might be extended to some of the candidates who didn't initially make the short list.
You could say that the graduate department is holding those promising candidates "in reserve."
@NovaliumCompany Personally I dont think theyll be a fight with AI, nor do I think that enhancing the brain is where we're headed
Anonymous
9:26 PM
> Serge is remembered fondly for entreating his students, cajoling his students, screaming at his students, and especially for throwing chalk at his students.
What would be a good resource if I was interested in the configuration spaces of various systems?
Also, does anything that can be parameterized by a single angle share $S^1$ as a configuration space and you just equip it with different metric? Say pendula and (damped/driven/regular) harmonic oscillators all have that configuration space but differ in metric?
I'm tutoring high school students. I've always taught them that:
A charged particle moving without acceleration produces an electric as well as a magnetic field.
It produces an electric field because it's a charge particle. But when it is at rest, it doesn't produce a magnetic field. All of...
I don't know if it is because of my latest question on main or because of all good help I am getting. can someone tell me if there is a reason I get more faster as I obtain more?
The Problem
I was going to write a question here asking what the appropriate response is to incorrect upvoted answers, but I realized that I'm far from the first person to ask this, e.g.
How should we deal with upvoted incorrect answers?
Are technically wrong answers and comments allowed on ph...
