At the watering holes where professors gather to bitch about the trials of their days I sometimes hear complains about how students these days are so uncertain of themselves that upon being told a fact in plain language they will immediately ask you if that fact is, in fact, a fact.
I'm blessed enough to rarely encounter such behavior in my students.
@3075 It would, I really want to get to Waterloo. Off residence is cheaper, but I'm moving to a place where you're literally the only person I know, and I don't even know your first name. I need a roomate so I won't be utterly alone
@0celo7 No. That would be students either wanting to be spoon fed or just being annoying because they are young and it seems like a good idea at the time.
@0celo7 You should hear the stories of the things I did because I was young and they seemed like a good idea at the time. Except that I don't tell them.
@BernardMeurer Er ... I'm not sure I understand the context. Should you live on campus? Do you have to be near by to get the most out of college? Or something else?
I stayed in the dorms for almost all of undergrad. Less housekeeping. Close to class. And it was not very expensive then, but they place wasn't as plush as most are these days.
@BernardMeurer If you still want it after reading that and you know why you want it, then it's on your head. But failing those two things it would be silly.
@3075 So, the university will probably answer the questions "Does DMcKee have a Ph.D. in [subject] from you guys?" according to what it says on my diploma.
My diploma just says "Physics", but I say I have one in "Nuclear and Particle Physics" if the person I'm talking to would understand and care about that specialization.
user54412
2:31 AM
@3075 Some supervisors won't pay you unless you do their work for them. Others won't have any idea what you should do. And most are somewhere in between.
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@ACuriousMind Would you say that a QFT defined as operator valued generalized functions, with generalized numbers for coupling constants, sounds like a decent idea
@MAFIA36790 Hi MAFIA. If I edit some old questions (for example by adding tags) to active them, is this useful for the site? Do I bother some one by this job? If so, I don't do anymore.
user116211
@lucas That depends on the question; you need to have a good legitimate reason to make them active- like they are lacking a good answer or deserve more attention or tagging is necessary etcetera; otherwise don't make such edits.
Hi guys. When we calculate a QCD process (for example two particles go to two particles) and we use the renormalized coupling constant, why should we evaluate the coupling to the energy $\sqrt{s}$ where $s$ is the invariant mass? My book says that it is the only quantity of energy dimension that characterizes the process... but there is also the variable $t =(p_1 - p_3)^2$ that is independent of $s$. So, why do we choose $\sqrt{s}$ as energy scale?
@Slereah Um...if you mean your non-standard analysis stuff with "generalized function" (because a distribution is also sometime called a "generalized function"), then no, because non-standard analysis is (to me) just a way to get rid of the annoying $\epsilon$-management of standard analysis - what advantage do you think such an approach would have?
Coupling constants run with the energy scale $\mu$. But what is exactly this energy scale. My question is, if I have a physical process, how do I compute $\mu$?
There's nothing except convenience for choosing some particular regulator
In some cases, choosing a particular regulator is "physical" in the sense that it respects some symmetry of the theory, but, really, you're extracting the "finite part" of a divergent sum, which is well defined (see Tao's blog post on zeta function regularization) independent of the regulator. There's no physics in choosing a particular regulator as far as I can see
Anyone know how relativity explains centripetal force. Say the universe was empty, there was nothing but you, how do you know whether or not there is centripetal force acting on you?
@dmckee That's a very US-centric blog, isn't it? (Not saying it's necessarily better elsewhere, but some of the specifics, in particular exams and courses in "grad school", don't apply at all here as far as I know, and it's not "school", doctorate students are employees.)
Yeah, but a guest should have some appeal to draw people to the session. I get DanielSank as a choice, quantum computing has the potential to be interesting to other people
I don't mean how to choose the renormalization scale.. Suppose I set defined $g(M_Z)^2$ where $M_Z$ is the mass of Z-boson. Now, If I have a scattering 2->2 mediated by the coupling $g(\mu)$, which $\mu$ should I choose in order to have a good prediction?
@FrancescoS That depends how you defined $g(M_Z)$ to begin with (your "renormalization scheme", cf. my answer - you can choose the scale to be defined purely by the s-channel and at t,u-zero, or you can choose the scale to be defined by all three channels equalling the scale. Regardless, there is no unique answer to what you should choose as the scale $\mu$ for a given process
What $\mu$ you choose merely controls the convergence behaviour of your perturbative computation
But, How should the running depend on the channel I used to define the coupling at a given scale? The running depends on $\mu^2$... so, how $\mu^2$ knows it is taken in a s-t-u channel?
@FrancescoS Because you defined $\mu$ through choosing these channels! E.g. in $\phi^4$ theory setting $\mu$ means setting the resummed 4-point vertex to have precisely amplitude $\mathrm{i}\lambda$ "at scale $\mu$". It is your choice of renormalization scheme whether "at scale $\mu$" means "at $s^2=4\mu^2,t^2=0,u^2=0$" or "at $s^2=t^2=u^2 = \mu^2$.
@ACuriousMind Yeah. That's true. And I don't know enough about the academic experience elsewhere to even know how broadly the advice applies.
I get the feeling that my Canadian colleagues have a similar experience, and that while the details are considerably different much of what is said is broadly applicable to most of the British Commonwealth as well. Beyond that I'm at a bit of a loss.
@Obliv The point is that a lot of people end up regretting grad school at one level or another.
I enjoyed grad school enormously, but the economic cost has been significant.
@bernardmeurer the 100rsns blog @dmckee posted should only discourage people on the fence. Don't expect a leisurely life in grad school & beyond for many areas of study. If you want a leisurely life go into another field where the $$$ is. Only pursue higher education if it's something you know you have to do and you don't care what it takes.
right and I'm sure you would agree it was worth it @dmckee and you undoubtedly learned a lot there and grew as a person. I think that's worth economic cost.
It's pretty pointless to compare lives with other people imho. We all grow up differently with different desires. Unless you ignored them when deciding to become a physics teacher, I don't think living your classmates lives would satisfy you. @dmckee
that's why it's important to understand that grad school is the only option to satisfy your desires. It doesn't matter at that point how harsh it is, if it lets you get what you want.
@Obliv Do you really know that? Many people seem to be able to learn to be satisfied with the lives they end up leading instead of pursuing the dreams of their youth.
My life would have been very different if I had not pursued the academic track., but that's not a value judgement.
I have the respect of my colleagues and get asked to do things like judge the Cub Scout science fair that suggest respect in the community. I have some flexibility in how I pursue my work that not everyone gets, but I haven't the resources to pursue some of the "bucket list" things my wife and I would like to do.
The thing I tell students is that further academics is not the "next thing" or the default path for them. That's why I am also suggesting that you know why you're going to grad school.
@acuri I acknowledge happiness is something we can create synthetically. Sure if you gave me a bunch of drugs to be content then I wouldn't care to become a physicist. I think that's similar to pursuing a different career & life to lead a 'content' life. I just don't think that's a valid path. If you strip yourself of all of your biological cargo except for your brain, got rid of all social/economic pressures, and asked what you wanted to do I think whatever that is, should be the thing you do.
Coupling constants run with the energy scale $\mu$. But what is exactly this energy scale. My question is, if I have a physical process, how do I compute $\mu$?
