Comments for Swans on Tea

Comment on Hey You, Stop Being … so … Unsafe! by Nick

Nick — Wed, 01 Jul 2009 14:55:03 +0000

I’ve never been content with the safety situation in any lab where I’ve worked, be it academic or government. (I’ve never worked for industry.) The safety rules were either too lax, too strict, or both.

For example, in the undergrad general chemistry labs at both of the universities I attended, students were required to wear full (hot, uncomfortable, fog-prone, vision-limiting) splash goggles at all times in the lab, even when no one was working with anything stronger than water. Meanwhile, directly over their heads in the research labs, grad students were transferring concentrated acids wearing nothing but T-shirts, shorts, and sandals. I generally knew (and know) enough to wear PPE appropriate to the job I’m doing, and I appreciated the flexibility offered by the absence of enforced rules, but some of my “cowboy” colleagues had their safety tolerances mis-set somewhere along the line and were (and are) courting disaster.

I’ve heard the “welding goggles” complaint (and made it myself) in the presence of visible OPO/OPA systems: “So, we need to block the Ti:Sapph output from 750 to 1000, the doubled Ti:Sapph from 375 to 500, the signal beam from 500 to 700…”

Comment on They Won’t Wear a Leather Outfit, Either by Uncle Al

Uncle Al — Tue, 30 Jun 2009 20:25:09 +0000

the longer the back is in relation to the legs, the less likely a dog is to flip over and the faster it can accelerate. Dachshunds, beagles.

Comment on Blackbird Singing in the Dead of Night by swansont

swansont — Mon, 29 Jun 2009 19:56:19 +0000

True. In general, though, the speed of sound depends on density. In an ideal gas, there is a relation which ties the bulk modulus and density together such that the dependence is on temperature. OTOH, the speed of sound is not the same at 100 km as it is at sea level, even though the temperature is the same.

Comment on Blackbird Singing in the Dead of Night by drew

drew — Mon, 29 Jun 2009 18:45:41 +0000

Hey pedantic man. The speed of sound varies with temperature, not density. Since pressure and density are directly related at a given temperature, any decrease in density is offset by a corresponding decrease in the ’spring constant’ pressure represents when describing sound waves. Temperature is the proportionality constant that relates the two. The speed of sound goes with the square root of temperature (sqrt(gamma*R*T) to be complete).

Comment on Blackbird Singing in the Dead of Night by Uncle Al

Uncle Al — Mon, 29 Jun 2009 15:05:11 +0000

Uncle Al knows a retired military air traffic controller. One can trivially look at shock cone angle vs. engine placement. An SR-71 doing Mach 5 was unremarkable. A speed run could launch it suborbital in principle, but nobody ever figured out how to restart the (cooled) engines at altitude - JP-7 was difficult to ignite at sea level. The SR-71 glided unpowered like a brick.

Comment on Blackbird Singing in the Dead of Night by Geb

Geb — Mon, 29 Jun 2009 13:46:43 +0000

It’s difficult to know whether to be impressed or not once you find out that the temperatures and pressures on the hull change so wildly that on the ground the blackbird’s fuel tanks don’t seal. Until it heats up, it leaks so badly that it needs to be refuelled in the air immediately after takeoff.

Comment on Doctor Incredible by drew

drew — Sun, 28 Jun 2009 06:21:48 +0000

Oops…I meant Stanford, I don’t know why I said Princeton

Comment on Doctor Incredible by drew

drew — Sun, 28 Jun 2009 06:02:04 +0000

Wow, Swan, good find…that ‘Academic Earth’ site is awesome. All of the resources the students get except for the prof’s time, absolutely free.

I just ‘attended’ the first 3 lectures of Princeton University’s “Machine Learning” class today.

Comment on Energy Balance by Uncle Al

Uncle Al — Sat, 27 Jun 2009 21:07:14 +0000

Malthus has a pat hand when compassion is more highly valued than reality. The universe exacts a terrible price from those who are inefficient (and more and worse when it is legislated inefficiency). Justice! Let the Gifted proceed unaided and the stupid proceed unimpeded. HIV is not caused by lack of funding. Anybody who believes universal opportunity creates pandemic poverty because only workers have money to spend is an ass.

Comment on Stalking the (Wild) Physicist by Uncle Al

Uncle Al — Fri, 26 Jun 2009 16:09:26 +0000

We then conclude that if a string theorist is caught shagging a sheep - who (either one) has an accomplished publicist - he rises well above his confrere’s who are content to avail themselves of more exotic, less public modalities. That sounds about right.