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I recently posted a somewhat sideways thought to twitter. Expanding the thought properly requires more than 140 characters, so I'll do it here rather than there.

Purple number one: Violet
Imagine looking at a rainbow. (If a real rainbow is available, stop wasting time reading this and go and look at it. Admiring pretty things is a vital and shockingly undervalued lifeskill.) Purple is the bit between blue and ultraviolet - since most people can't see ultraviolet, it is therefore the innermost chunk of the rainbow, fading into blue on one side, and invisibility on the other. This type of purple consists of photons with wavelengths in the rough range 380 to 450 nanometres.

Purple number two: Magenta
Now imagine looking at an LCD screen showing a picture of a rainbow. (Feel free to find one on whatever device you're using to read this if you've not practiced admiring pretty things recently.) It looks very similar, right? But your screen isn't emitting a single photon in the 380-450nm range; it isn't physically capable of doing so.

So far, this is actually entirely normal, as far as human vision goes. (Human vision, like almost everything else to do with the human nervous system, is a weird heap of barely functional kludges piled on top of other, older, kludges in a way that really shouldn't work but collapses surprisingly infrequently for something so absurdly incoherent. But that's another story.) Most colours can exist in either of these forms. So a yellow flower might be reflecting just a single wavelength in the 570-590nm range, or it might be a mixture of different wavelengths, some longer and some shorter, the average of which lies in that range[1].

And that's where purple gets unusually weird. If you want to show cyan, you mix green (longer wavelength) and blue (shorter wavelength), and your eye/brain interprets this as being something between the two. But if you want to display purple, you mix blue (longer wavelength than purple) and red (much longer wavelength). And then your brain says "halfway between red and blue is green, but there isn't any green here, so it must be something else", and shows you purple. Some of the magenta-purples you see when it does this are indistinguishable from the violet-purples that you see looking at a real rainbow. But it's possible to combine reds and blues to produce magenta-purples that (to a typical person's perception) don't match any wavelength of light at all.

There are other types of colour that can never be produced with a single wavelength of light - brown is the obvious example - but "Purple" is unusual, in English at least, in being both a chunk of the visible spectrum and a batch of non-spectrum colours.


[1] in practice, a flower is never going to be reflecting just a single wavelength. In fact, even sodium streetlights emit two, albiet two pretty close together. But imagine a flower that does, OK?
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SpaceX have just successfully landed the first stage of a Falcon 9 rocket. From a technological viewpoint, provided that the rocket is indeed fully (or even mostly) reusable, that's a pretty big step forward. Even if that rocket can't be reused, it's a solid move towards making one that is. I was impressed.

But then I started to think about the physics of it from outside the aerospace technology angle. Essentially, what they did was this: They dropped a 25-storey building out of the sky, and used controlled explosions to land it exactly upright on a floating platform that's narrower than the building is tall, without damaging either and leaving the combined system nice and stable.

When I look at it like that, it's no longer impressive, it's incredible.

Science is awesome.

ETA: Actually, that's not quite right. The height figure I was using (just over 70 metres) turns out to be for the whole Falcon 9 rocket, rather than just the first stage. The part landing on the barge is only 44m tall, so that's only about 15 stories, not 25. Which doesn't make the achievement any less amazing.
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As I wandered through our local supermarket, not buying anything (it was cold and dark and I wanted a walk somewhere that was air-conditioned and not raining), the label on a pack of bottles for minimising the hassle you get from airport security caught my eye. It asserted that the 100ml bottles in the bag were suitable for "All gels, foams, pastes, and other liquids". Is it unreasonable for me to feel that even the marketing nerk who wrote the text should have been able to identify that "gels, foams, [and] pastes" are by definition emphatically not liquids? Is that specialist knowledge that I shouldn't expect people to possess? (And if I asked for comments explaining the relevance of this posting's title, who would be first?)
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Not only did NASA manage to lower a one-tonne robot onto another planet using a sky-crane. They also managed to programme another robot three days in advance to take a photograph of this happening during the one-second interval when its camera would be pointed at the right spot.

I can understand people who think there are more important things to spend money on right now. (Although space science would be a very long way down my list of things to cut. Come back when you've got the US defence budget down to within an order of magnitude of what NASA gets, yes? Because that change will feed a lot of starving children.) But anyone who doesn't think it's an amazing achievement is beyond my comprehension.
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I'm going to get my book posts a bit more up-to-date, honest (being four months behind is a teeny bit embarrassing), but in the meantime:

One of the books I've not written up yet was Robert Peston's Who Runs Britain?. Coincidentally, Peston recently gave a very interesting lecture on the future of the media and journalism, which I recommend to anyone who hasn't read it.

Like most people I know, I don't have enough shelf space. I want Neil Gaiman's bookshelves. (I wouldn't mind his library, too, and I suspect his house is nicer than mine, but you can't have everything, can you? :)

I also want one of these. OK, it's idiotically impractical for pretty much any actual washing scenario, but with design like that, who cares?

Continuing the vaguely sciencey theme, Ben Fry has put up a rather neat Flash program that compares the text of the different editions of Darwin's "Origin of the Species" (and allows the viewer to look at them, word by word).

A few months ago, the Hubble Space Telescope had a camera upgrade. The new camera is now operational and taking awesome pictures, while Ethan Siegel has put up a nice compare and contrast of the capabilities of the old and new cameras.

Speaking of pretty pictures, Michael Dashow's website includes a rather neat piece of art he did demonstrating the dangers of mistakes in a Cthulhu-oriented workplace. A lot of his other stuff is good, too :)
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Ed Yong of "Not Exactly Rocket Science" has done a fantastic parody of the media's deranged excesses over Darwinius masillae. Presumably as a break from his continued excellent writing on actual science.
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This was bad enough. The idea that a major publisher of peer-reviewed science journals would publish a fake medical 'journal' in exchange for cash from a drug company is repulsive at best[0]. But they didn't stop at one. So far as anyone knows, this is limited to Elsevier's Australian division[1][2], but do you know what? I don't care. Even if the top of the company was merely happily ignorant of what was going on, I want their entire journal publishing empire to collapse as a warning to other people. It's bad enough to deal with creationists, quacks, and other loonies publishing allegedly serious journals full of b***s***, but to have a major scientific publishing house fake one is completely unacceptable (not to mention the fact that this plays needlessly into the hands of the 'modern medicine is a sinister conspiracy run by big pharma' morons). The initial discovery was the "Australasian Journal of Bone and Joint Medicine" (and relates to an ongoing court case against the sponsor of that 'journal'), but the known others now include two cardiology 'journals' as well as one on neurology and two on more general topics. It's not in any way impossible that people have died as a result of this, and if they have, then I hope Australian law includes a corporate manslaughter charge to take the b******s down with[3]. Putting other people's health - and lives - at risk (all the examples discovered so far are medical journals, remember) for profit is so wrong that words just fail me.

[0] Dr Goldacre's article also discusses the assorted other revolting tactics used by Merck in attempting to prevent people finding out that the drug in question was dangerous, whereas Orac's two posts are specifically about the Elsevier 'journal' problem.

[1] They're running an 'internal review' at present, and hopefully lots of deserving people will be fired (or, better yet, executed), but even if it really is a local problem[2], the damage to the company's reputation will be huge, world-wide, and long-lasting - and well-deserved.

[2] Since the website for Excerpta Medica, the 'strategic medical communications' division of Elsevier given as the imprint for the fake 'journals', says that it employs 200 people at offices in the US and Europe, it seems unlikely that this is a small local problem. See comments on Orac's two articles linked to above for more information about this....

[3] An unfulfilable idea, alas, as the best you could do would be to show that statistically speaking the number of deaths was higher than would otherwise have been expected, but that's not proof of what caused those deaths, or that they weren't a random blip. While there would be some justice in it, I'm not convinced that such an argument passes the 'reasonable doubt' test, although that might depend on how unlikely you could show that the bump would be as a random event.
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Further to previous reports, the bridge connecting Wilkins ice shelf to Charcot Island has finally snapped. But you must understand that there's absolutely no evidence for anthropogenic global warming, and no need to do anything about carbon dioxide emissions or anything like that. Absolutely not.

Shiny toy

Mar. 31st, 2009 12:07 pm
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I don't own one of these, but I'd like to. (Photo taken by the crew of the Discovery during STS-119, when they delivered the latest set of panels.)
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The BBC has some fantastic footage of Narwhals travelling through cracks in Arctic sea-ice, while one of their reporters has blogged about the government's scientific drugs advisor's frustration with the way figures are taken out of context - both by the government and by the press.

In other news, current extinction risk models may be excessively cautious in their assumptions - the actual risks may be a hundred times greater, or even higher. The periodic reports that the Earth's magnetic field is just about to flip poles would seem to be rather overstating the risk of it happening soon, otoh. (nb: to a geologist, 'soon' means 'in the next four thousand years' :) Meanwhile, Ed Yong has posted summaries of a whole range of stuff, including rapid speciation in insects and their parasites, butterflies evolving resistance to bacteria that killed only the males, and the (unsurprising[1]) research suggesting that if people learn to distinguish better between members of another cultural group, their implicit bias against that group diminishes. Of course, if they're consciously bigoted, there's not much you can do for them.

[1] to me, at least. Pigeonholing people leads to stereotypes and bias; recognising that members of $GROUP all look different will make it harder to assume they're all the same inside (even for a determined bigot, I suspect, but certainly for anyone who wants to think of people as individuals rather than as $PROPERTY-people).
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Today, in case anyone didn't know and wants an excuse to look at it, is the 40th anniversary of a remarkable first: three men in a metal box a long way from home saw Earthrise for the first time in human history. A couple of minutes later, they managed to find some colour film, and took a second picture: one of the most iconic images of our time.
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Some interesting research done recently, and usefully summarised on the Effect Measure scienceblog, suggests that in fact a significant proportion of "microwave safe" plastic containers may actually be rather less safe than ideal. Many of these containers turn out to leak potentially-toxic chemicals left over from the manufacturing process into their contents when heated. Storing food in them at room temperature (or below) seems to be fine, but heating them in a microwave or oven may not be.

In even more alarming news, which I missed until recently, ESA satellite images show that the bridge connecting the Wilkins Ice Shelf to one of the islands that anchor has almost completely disappeared since February this year. The most recent data show new rifts in the main body of the shelf, suggesting it may now be on the verge of collapse.

Finally, on a lighter note, a Canadian police video camera captured some impressive footage of a meteor coming in low across the night sky:
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Erich von Daniken is still spouting hilarious nonsense, and respectable scientists occasionally go to his lectures, in order to make fun of them post analyses of the assorted major flaws in his theories. As one of the commenters observes, I had rather assumed that the man was long dead, but....

On a lighter note, let me show you these analyses of the usefulness of chocolate teapots and tinfoil hats.
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Today's real news: an article due to appear in this week's issue of Science will contain the first ever direct images of extra-solar planets.
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This looks promising, although this summary may be considered just a little overoptimistic....
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What with financial crises, USAnian elections, and other excitements, there hasn't been much comment on 2008 TC3. It's a small rock that was no danger to anyone, but it's nice to know that we are actually starting to be able to see these things before they hit us, even if we only spot them a few hours in advance and have no way of stopping them. At the very least, there'll be time for one hell of a party before the next KT-type impact :)
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This year's Ig Nobel prizes have been announced. If the AIR site is down (it was collapsing under the load as I started this), brief details can be found at the BBC.
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Someone elsewhere pointed me at this page, which collects together photographs from the half-dozen assorted probes currently orbiting round/sitting on Mars. It's actually about a month old, but there are quite a few images I'd not seen before there.

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