@EmilioPisanty For the large particle physics collaborations I was a part of students made up roughly 60-65 percent of the authors. The rest were post-docs and "faculty".

But "faculty" included permanant staff at majors labs.

Important tasks that required a lot of hours were usually given to post-docs and leading graduate students. Because they have more hours to give to that kind of work than more senior people who get interrupted a lot for meetings and paperwork.

Hello everyone, I've heard a couple of times that one trillion electron volts is about that of a mosquito in flight, and so the memories of having a mosquito bump into me gives me a sense of what 1 TeV can feel like. I was just wondering if anyone has an even lower powered analogy that, like the mosquito analogy, is just as easily relatable?

@Louis Do you mean like a macroscopic example of a GeV?

I suppose a few milliseconds of bright starlight (eg from Sirius) entering your eye is around a GeV.

Anyone interested in answering a basic GR question over on Astro? astronomy.stackexchange.com/questions/30419/…

@PM2Ring I'm sure Duffield will be on it momentarily :-)

@rob I meant something that we would be touch sensitive to (human skin).

The tiniest example of...

@JohnRennie Very droll. ;) I was hoping someone else could get in first...

@PM2Ring I'll have a look ...

@Louis If you can feel a thousandth of a mosquito, you're doing better than me.

@Louis Well, take your 1TeV mosquito and discard 99.9% of it, and you have 1 GeV. Instead of imagining a mosquito striking you, imagine a tiny fragment of its wing, or the "foot" segment of its leg, striking you at the same speed. Might not be enough energy to trigger a tactile sensation.

@JohnRennie Thanks!

Hello, I am looking for technical bookshops in the Central London area, I am mainly interested in computer science, math and stats books. I am interested a lot also in second hand books of the same subjects. Thank you

One lazy afternoon, about 30 years ago, as I was drifting off for a nap, I had a brief flash of perfect blue in one closed eye. I suppose it was some kind of spontaneous phosphene. But I like to think it was a brief burst of Čerenkov radiation from a cosmic ray. ;)

@PM2Ring done!

@JohnRennie Looks good to me. I know enough GR to read that answer, and agree that it's correct, but not enough to write it with confidence.

Besides, I always enjoy reading your answers. Even if I don't always learn some new physics, I get a good example of how to teach physics. :)

I think I like some variant theories of GR more than GR.

like Einstein-Cartan theory, teleparallel theory, Poincare gauge theory.

I like Quantum Gravity theory. Unfortunately, nobody knows what it is yet. ;)

@dmckee sounds about right

The question is, why does it always have to be that

> more senior people who get interrupted a lot for meetings and paperwork

is the only way to have job security in modern science

@PM2Ring I also like quantum gravity, but due to my deficiency of some prerequisites, when I tried to study some theories of quantum gravity, like loop quantum gravity, asymptotically safety gravity, etc. my understanding of them is very limited.

@EmilioPisanty Never underestimate the effects of Administratium. Even in tiny quantities, its insidious anti-catalytic effects are pervasive.

these three consecutive days I waked from dreams of dense scenarios. Today I waked from a dream in which when changing seats, my classmate sold my book of Engineering Mathematics, which I left in my old seat, to a second-hand bookstore; he considered that book is discarded by someone. I felt so frustrated because that book is mine. I asked him to take me to the bookstore to redeem the book, but the boss could only find other copy of that book. I was not frustrated and continued searching for it.

After searching for several places, I still couldn't find my book ... I waked feeling a relief it turns out just a dream.

@CaptainBohemian That's really nothing compared to e.g. having to evacuate a burning building where people literally see windows fell to the floor as it get consumed in a blaze, being printed a tracker by some adversary thus cannot return to base in fear of disclosing the headquarters location, and sleeping in a bed, only the next day found it is infested with bugs

and to top that, couple of gunners firing poison syringes to you and you need to be flexible to prevent getting hit

Anybody know how to do iii? I don’t understand the derivation :/

@Secret I have dreamt that the building I was in is on fire several times---I was fleeing from the fire panically; fortunately every time I can escape from the fire safe and sound. I also have dreamt of fleeing from a flooding underground---water keeps flowing in---and fortunately I can escape from it before I was submerged. I have also dreamt of fleeing from a whirling building due to earthquake---I also escaped from it safe and sound eventually.

lucky you, I have dreams where I actually got killed by some of these things as the scene turns black

@Secret As for gunners firing poison syringes, I have never dreamt of that kind of scenario, but I have dreamt of that my country became a battle field wherein enemies are everywhere---they used cane-like stuff, e.g. rattan, stick, to whip us when we didn't pay attention so when we went outside, we need to be very cautious to prevent from being whipped by these enemies.

though I have never really experienced these horrible scenarios, I have actually lost my books in classrooms several times and I usually felt very upset when that happened.

↑ lol dream competition :o o_O

reminds me of Inception 2010 :) imdb.com/title/tt1375666

@JakeRose Maybe try $\partial_r(re_r)$ or something like that, if you have any dependency on $\tau_r$ in $e_r$ then the derivative $\partial_r(r\tau_r)$ should pop out

@EmilioPisanty In any big effort (like particle physics or an international-scale radio interferometric observation, for instance) there is a lot of coordination and cross-checking, and interfacing to be done.

That kind of work scales up faster than linearly with the size of the effort.

And a large fraction of it must be done by people who and technical experts on sub-project and have a "big picture" view.

Post-docs can get roped into this stuff, but it mostly calls for people who have been with the project long term and that means faculty.

I was wondering how the HTC Vive and other similar systems track hands? (and overall body structure)

I mean, how does the HTC Vive track the arms crossing and stuff? For example in VRChat?

@NovaliumCompany The Wiki article says it's infrared-based tracking software called "Lighthouse".

How to know whether a given metric is isotropic or not?

@dmckee hmmmmmm.

And that leaves the tasks which are more intensive but more narrow to be assigned to students and junior postdocs?

@EmilioPisanty Yep. And quality control in those jobs comes from good mentoring.

My bosses made me attend those meeting that were directly connected to my assignments (and let me out of the others).

I assume that was so I would be available to discuss technical questions with my opposite number (often also in attendance) and get a taste of that end of the job.

It gave me enough understanding of how big projects run to make me happy to be working in a small group setting...

Because @PM2Ring is right about the costs of administration. There is a reason that DUNE is a billion dollar project and the Jame Webb telescope is a billion over budget.

Big is hard and expensive.

My cooking is a mish-mash of things I picked up in different places and from different people, but I do a lot of cooking from the American south-west, some Indian and some Chinese.

Then I see

and I want to say "Everything?".

I mean, it's one of the spices I buy in bulk.

Poor OP has been missing out.

@dmckee Agreed! My cooking has a strong Indian influence, but I use cumin with lots of non-Indian things too. As well as the usual suspects like bean-based dishes, I reckon it combines well with many vegetables, including tomato, spinach, the cabbage family, and sweet potato.

I suspect it would also work with pumpkin & other squashes, but I have a bit of an allergy to the whole squash & melon family. I prefer freshly ground, or just crushed, but I got a huge bag of ground cumin on special a year ago, and I'm still working my way through it. Yes, it has lost some flavour, so I just double the quantity. :)

@dmckee BTE

Grrr. Phone fumble fingers. Sorry.

@dmckee BTW, the reason I posted that stuff about privatdozent isn't that I support these things, quite the contrary. As my rant the other day indicates, I think it's a sorry state of affairs that science doesn't get more support, and is generally not held in the high regard it deserves.

I mentioned the privatdozent system to point out that the postgrad situation in the US isn't isolated to the US, and isn't a modern phenomenon. There's a reason that so many big names in the history of science were from the aristocracy and other upper-class families.