I'm still concerned about the black vs white heat emission issue. The photochem and energy transport phenomena don't change on the 'outbound' side for white vs black. Perhaps the kinetics will change - but that wasn't part of the discussion before. And yes, the heat transport phenomenon will definitely be tied to the material, surface structure, etc. - I agree on those points that others have raised. But, those points are in agreement with my original point, not in opposition - the variable of concern for out 'other' category is NOT color, but material! Color becomes an issue when determining the energy in, not the energy out.

People are getting caught up on the issue of a blackbody vs whitebody. They will both emit light from the 'blackbody' process based on temperature, not color. Remember that the terms 'blackbody' and 'whitebody' are tied to thepractical experimental side that led to the fundamental measurements.. All objects will have both blackbody (emittive) and whitebody (reflective/scattering) behavior in different proportions. Perhaps I was not careful enough in setting that up in my earlier post. In the end, the albedo differences some pointed out are tied to the reflective/scattering behavior generally 'drowns' out and blackbody components. So I are that a low albedo is preferable for a 'spy' satellite (and the sort), but that has to be balanced against the light absorption heating.

So, the discussion is a tangent from the original point - the whatever-paint-body will lose a small amount of thermal energy by emission of a photon. This process will likely be slower than the rate of absorbed photons in all cases I can imagine for an orbiting body (unless perhaps it's parked in the shadow of a planetary body - then we'd need numbers for Mie scattered light around the planet, etc. But now we're really running afield.) So:
      energy out - independent of paint color
      energy in - minimized for low absorptivities (i.e. white or reflective)

So, if you're minimizing solar heating for an orbiting body, black is a poor choice. When you begin balancing this against detectability, you have a more multivariate problem. But even there, I would aim for a high reflectivity approach that is directional, and directed away from potential observers. Or (in the ideal world where we do not live) for 100% efficiency solar panels (in the realistic world, perhaps a transformation of the light into something mostly other than heat can still thread the needle. Again, tangential.)

For my money, I'm going for a surface that's highly reflective but highly directional, and I'd pont is somewhere I never expected an observer. Better yet, I'd have an umbrella (black) set up in that direction in case an observer ever was there. And, while I'm wish listing, I'll put that high efficiency solar converter at this point, to further mask the 'beam' reflected and turn it into useful power, that doesn't heat the real satellite (so we want a tether with minimal heat transfer.)

(Merry Christmas all, the outline for a DARPA grant - if it hasn't already been done.)

Actually, no it's not... See a comment up the page.

If anything, Ohnoitsaguywhoistrolling... If it's the real Roland, your zombie-hunting fantasies are about to come true.

So, we're now jumping on the bandwagon where everything is spying? (I know, I must be new here...) Because, what _I_ read was a barebones article (193 words!!!) barely longer than the summary, that basically says they are using imaging of parking lots (and they implied traffic patterns as well) to see how full they are. I might be wrong, but my response is already almost longer than the article which makes it difficult to tell. I say it's a valid approach, spun up via alarmist phrasing to look like a privacy article.

Please, next time you flee in a panic from road surveyors who 'are there to spy on you and determine your vectors', please stay in your lane, because I'm already dealing with enough poor drivers... Deep breath - just because they have eyes pointed in your general direction that does not constitute spying.

Not only would I insist that this is an incorrect statement, that isn't what your link says at all.

Black items will ABSORB more light. When light (i.e. the energy contained in a photon) is absorbed by a molecule, there are a certain number of likely fates for this energy. Remember, 'what goes up, must come down' - an excited molecule will relax through one of these processes:
  - fluorescence or phosphorescence - the light comes out a different (and lower energy) color (these differ by how long they take to occur).
  - photochemistry - they react with something or break apart while excited. Bonds are made or broken.
  - vibrational energy (i.e. HEAT) is given to surrounding molecules.

The third (heat) is by far the most likely outcome, and occurs alongside the other two EVERY TIME! In other words, because it is black it ends up with MORE heat energy. It is not radiating more heat because it's black; it is getting more heat because it's black, which as a result means more heat is given off.

AND - a black satellite will overheat much faster,which goes directly against your logic.

There are a number of different tile types that are black: http://en.wikipedia.org/wiki/Space_Shuttle_thermal_protection_system gives a nice rundown.

The only way that black would help dissipate heat is that when heated up, the blackbody photons they give off would yield a minor loss of heat energy (multiple small vibrational packets of energy put together to make a light photon, if you will...)

It sounds like this could be a treatment that (with some modification) could be used to treat folks with laser damage to their eyes (or any other damage caused by highly focused light.) In that case, the 'donut hole' would be fairly small. To some degree, I also wonder if defocusing an area that illuminates small blind spots might be advantageous - instrad of a blind spot, instead the person would have a blurry spot...

Playing the Devil's Advocate for a moment, I do hope that people will ask themselves how they would respond to this parallel case:

A senior clerk in a court office (e.g. parking permits and citations - feel free to pick what one for yourself) has acceptable performance in the office. On the 3rd page of the newspaper, a photograph of this person at a racist rally (e.g. KKK) appears, and they are holding a sign backing these racist beliefs. Should the local government feel that their public behavior off-the-clock may impact their official civil function? The next-tier officials are concerned that patrons (remember, not all court patrons are citizens/taxpayers/etc - hence, patrons) may justifiably feel that this government-provided service may unfairly or ineptly handle their issues based on their public, non-job-related performance.
- Is this grounds for disciplinary actions?
- Should this same standard be applied re: teacher/strippers?

And for those who like to assume the question = the answer, notice that I didn't take a stand on any side, I'm just pointing out that we should either be consistent in our reasoning between these cases, or have a well thought-out reason that they should all be treated differently. Food for thought.

I'm a chemistry professor, and I want to agree with this post and follow-up. The bio side has lots of labs/departments that lean Mac-heavy. In chem, organic chemists have a larger Mac population than society/rest of chemistry, but it's still well under 50%. Physical chemists that are experimentalists are probably using something command-line on their instruments, because they probably built them themselves in the last few decades, and the "if it ain't broke, don't fix it" rule applies (plus more modern computers aren't so great at supporting the connections needed, so you'd be rebuilding the whole instrument anyway.) The computational chemists typically use $nix systems, because they're working with computing clusters - though many of them do their analysis on PC/Mac platforms.

BUT, to re-address the original topic - I don't think there IS a good go-to operating system to use in a high school that will prepare students for the higher sciences, because as many have posted so far it depends what those students want to do later in life. As a teaching&research oriented prof who spend 2 days a week in the K-12 system for 4 years doing on-demand professional development and curriculum deepening, I can say that there are two key criteria to use in deciding what tool to use with the students:
- is the tool "ready to hand"? - http://www3.interscience.wiley.com/journal/63450/abstract is an example of what I mean
- are the 'big ideas' the students will develop from the task generalizable enough to be platform-independent?

These are central themes of the Technology in Science Education course I teach, for what it's worth.

The NYT article was actually pretty good, but for those who want a bit more 'meat on the bone', here's the 2009 research project report:
http://caracol.cos.ucf.edu/reports/2009.php
There are some nice examples of the LIDAR images at the end of the page in the Figures section.

Cardboard box + lobby = happy broke chemist ;*) I agree about simplifying though - I think I finally tossed my Vic-20 in my last move. And boy, do I ever need that audio tape drive daily since ;*)

Actually, the area people that would still need/use these parts. In my old research group, I was babying a 286/XT switchable computer because its power supply liked to act a bit funky. We had already cobbled together a battery to maintain the BIOS settings (after I spent an entire day of trial and error getting the BIOS to be able to read the hard drive - documentation was lost to the world...) And we were always on the lookout for old computers being tossed from the department to keep flush with 5-1/2 and 3-1/4 drives. And that's just for this one computer - I'm not even bringing up the 386, 486, old Mac, and other tech we had in that lab.

"But why not upgrade to X?" "Oh, that's stupid, the Y is way cheap now!" I can hear some people ramping up to make these comments... Here's why - if it's not broke, don't fix it. And, if we had that $5k handy for the X or Y you're suggesting, we'd rather spend it on something else altogether! Our electronics rack may be replaceable by a $10k digitizing oscilloscope, but not only did our system already work, it could do specialize pulse rejection, finer amplification, etc. But the important part is that it already worked.

So, consider asking your local instrumental/analytical chemist if they need the parts. And if they don't, you can even offer it to the physicists... ;*) Or, I suppose you could start a side business reselling these components to science folks, but then you're going to have to hoard even more, which seems to be the cautionary point of the article.

Do you recall ever being given a blurb in a syllabus that strongly suggests that the optimal approach to learning in a class is to:
- read the materials before class (even a cursory read will do)
- come to class to gain connections, context, and detail for the more subtle points
- study after class to do the 'heavy lifting' of mastering the details?
Following that approach may help you with the "can't really use what I've been taught or contribute to discussion/examples until I've tried out [whatever technique/method we're learning] on my own in my own time" issue.

It's a lecture, and not a class, because with large dining halls, a fleet of academic/social/athletic buses, computer labs that require constant updating, etc., most campus administrations have moved to larger-sized intro-level courses and reserve the good instructor:student ratios for higher level courses (where the effort will support their discipline's students) rather than using scarce resources on intro/gen-ed classes. That's why it's a 'lecture', and not a 'class'. However, most of your profs have made a major commitment to educating (take hard science faculty - they choose beginning salaries in the $40k-50k range, rather than $120k+). Trying to maximize your learning gains IS the prof's business, actually (in the business/career sense), along with using the rest of their hours to contribute to the field.

The good (and still energetic) faculty try to offset these large-sized classes by using approaches that try to build back in some of the in-the-moment feedback from a small-class setting - both for the students and themselves. e.g. That's one of the things we're trying to do when we have you use those 'clickers'. For many of us, it's the reason for online homework systems - not because we're lazy, as we're often portrayed, but because we see the same common mistakes over and over and these systems do an improvingly-passing job of giving feedback as you're learning. We try to spur on classroom interaction. Are we always successful? Nope - and the still-energetic faculty also have to overcome the difficulty of learning this trade (teaching the highest-level classes) IN ADDITION to being a top-tier participant in their field. (Those who can, do, those who can try to do everything well at the expense of a life and sleep, teach.)

Why do I keep referring to 'energetic' faculty? Because, as time goes on it's simply too draining to fight the room full of 50/130 students staring at their screens. Seeing solitaire cards (or worse...) reflected back throughout the room. And not interacting/participating/responding to your efforts to reclaim the small-class opportunities for them. You see, those students on their laptops, the ones tuned-out, the ones 'showing up' in body, but not caring about the class - they're the control rods in a reactor. And by inserting them in the classroom, it has the same effect - it kills any amplification you get from having many minds in a room together, and reduces the classroom into a YouTube video - but there's now actual YouTube videos in the room that have skateboarding dogs, and stoichiometry can't compete with that for many people.

So, it's a negative feedback loop - you complain that the class is pointless, so you entertain yourself instead. Blunting any efforts on the part of the prof to improve the experience for yourself and those around you, and make it NOT pointless. The prof burns more hours/energy trying to overcome this. Finally, many simply give up and give over-rehearsed slides/monologues to the large classes, and save their energy for the 10 person majors-only class that really digs in with you, and feeds off of one another to construct a deeper knowledge of the material than any of them had from the textbook alone.

Yeah, feel free to roll your eyes at this - to say that no (or not enough) profs try as hard as I'm claiming. Whatever - you can pick it apart point-by-point, and we can have a running text battle for weeks! The big idea is: this is the view point from the 'front of the room'. And it's why some profs are trying to pull the control rods out of the reactor. You may not think it works that way; you may not care; you might be right! But we're trying to improve things, not just hearken back to the 'good old days.'

If there is an additional energy input, and if that input is highly efficient, I'm ok with the energy balance. If we consider the trash to be thrown away (ah, love what I did there...) then it's energetically lost. That means for an additional energetic input of 8E8 BTU (I rounded up for high-but-not-perfect efficiency), we get fuel worth 19E8 (scaled to matching exponents). There's something to that sort of process - it's like having a huge interest rate savings account.

And let's remember that converting crude oil into fuel forms requires energy inputs (hydrocarbon cracking, etc.) - but the energetic 'loss' is worth it to us since we get a portable energy source with more energetic value than we spent (ignoring the intrinsic energy from the fuel oil, which =0 to us in terms of utility until after processing.) As long as we break even (or better) in terms of processing energy input vs. energy of the fuel output, we lose nothing we haven't (literally) already thrown away.

If, of course, their information is otherwise complete and not overstated, and if the energy input is efficient enough to break even or better.

That would be because different educational activities can have different goals. I give analytical chemistry exams that are supposed to be somewhat collaborative, to provide an opportunity to learn (something called a "formative assessment") - this gives the students peer-guided instruction, and gives me feedback about where they stand in the process.

But, at some point I'll need to know how the individuals are getting it. These assessments/assignments may still be a formative assessment, depending on how I am using it as the instructor. Eventually, I have to sort the students based on achievement (or maybe I don't - this isn't the place for that debate, but I think we can all agree it's the most common practice) - this would be a "summative assessment".

And your example of homework is relevant - profs will often not care about whether it's done solo or in groups. But, when a _project_ contains an explicit requirement for solo work, it's (supposed to be) because the instructor has a purpose - and how often do prof.s explain to their classes their summative/formative intent? These intentions may be opaque to the student.

In reality, most profs are pretty savvy about how they work (even if you don't see it) and are using a mix of summative and formative goals in their grading and assignments. Discussions on /. about cheating and education have lots of people coming out of the woodwork to say, "I think this educational approach is dumb, so I did what I wanted instead - and I say it's more authentic!!1!", or some variant of this. I love the hubris involved in assuming that not only does the student have a better awareness of the material and the 'realpolitik' of the eventual career, but that they know education better than the prof (and that the prof's goals are necessarily transparent). Or that the classroom is only supposed to emulate the daily job - that students should learn only to consume knowledge and approaches, not to originate them ("When you get into a corporate environment, "cheating" is actually preferred. No reason to re-invent the wheel when there is existing code that gets the job done." - http://news.slashdot.org/comments.pl?sid=1547360&cid=31111942). And yet, how does the student produce new work unless taught how? That's one of the curricular decisions the instructor makes - am I pursuing the 'originator' or 'realpolitik-daily' approach as my learning goal today?

Those wearing the instructor-hat were a student for a long time, and (should) have an awareness of the benefits of group work. But when students simply declare that they've decided to ignore rules and requirements because they've chosen their own goals, in my experience they're either:
    so self-aware in their learning that they'll succeed no matter what;
    or they're being lazy or self-delusional and using their own notions of 'what good learning is' to justify it.

Schawlow was at Bell - Maiman was at Hughes. I didn't bother with cites earlier, but I was pulling from Jeff Hecht's "Understanding Lasers" (3rd ed.) book for the Maiman info (nearest cite I have to hand - it's the text for the lasers course I'm co-teaching...) A quick google gave me Schawlow as being at Bell, but I haven't followed that part any further. If my memory serves me right, Schawlow was looking into other gain media and bypassed ruby initially, but during the publicity after Maiman's success, many people revisited it (and if I remember the anecdote right, the photographer was disappointed by the effect of the 'wimpy' flashlamp, and asked him to substitute a bigger one - and most people followed this 'design' as a result!)

Either way, I think we both find the same punchline - Navy funding was the initial MASER spark, a combination of private and public money was the kindling, and the wildfire happened finally in industry.

He was talking about a laser, not a laser printer (the word "printer" never appeared in the GP.)

Replying to the entire thread here;
    Ammonia maser = 1953 - partially funded by US Navy as part of radar-type research (at Columbia)
    Funding for laser development = intervening years (ARPA, private, etc. funding)
    Ruby laser = 1960 - Hughes Research Laboratories

If anything, this is an example of the traction that comes from using public funding to stimulate scientific advancement until the public sector jumps in. HRL was excited enough that they publicized the heck out of the development, and the way corporations ran with it in the subsequent decades does show that companies would do well to keep pouring money into R&D (ala Bell Labs) but that public funding often gets the ball rolling. And oftentimes, that seed money comes with military aims (better radars) that gain massive traction and yield huge benefits in divergent fields (here, everything from music to telecommunications to supermarket checkouts.)