For a time, the Descent: Freespace and Freespace 2 filled a gap that the failure of XvT left in me. I was very disappointed that they didn't continue the Freespace series. They really were fun, and had some top-notch graphics for their time!
Freespace II r0xx0rs.
It was obviously written by someone who practically worshipped X-Wing and Tie Fighter, because the game mechanics are identical. Completely. Oh, everything has different names, but when you get presented with a new weapon that fires fat blue bolts of energy that can disable a ship without damaging it, you know it's an ion cannon.
It also runs on modern hardware, or at least modern-ish (it runs beautifully on my GeForce II), and looks beautiful. It has big explosions, and glowing red nebulae that are genuinely disorienting to fly through, and complex ships, and it's got some capital ships that are almost beyond belief: they take minutes to fly round. Really.
If there's anything wrong with it, it's that it's damned hard, and that the storyline just doesn't grab me. Tie Fighter (never played X-Wing --- die, rebel scum!) borrowed off the epic Star Wars story. Freespace hasn't, which means it has to work much harder, and I don't think it quite manages to pull it off.
You know what? I'd love to see a total conversion for Freespace 2 that remade Tie Fighter. Now, that would be a good game.
(I'd heard that Freespace 2 had fallen into a legal hole that meant that nobody owned it, and so was legal to download. It seems unlikely to me, but does anyone know anything about it?)
IANAN, but it occurs to me that disabling Galileo for a particularly area is going to be a quite different matter to disabling GPS. Because the US owns GPS, disabling it merely involves instructing the satellites not to transmit useful information to a particular area.
Galileo, OTOH, is not owned by the US, and it strikes me that it's extremely unlikely that the US government will ever get root on the Galileo satellite network. Therefore, disabling Galileo for a particular area would require brute force approaches: physical destruction of the satellites, which would have knock-on political effects that I would hope even Bush would balk at, or else on-the-spot jammers.
Either way, preventing a rogue state like, say, Canada from access to Galileo would require significantly more committment than with GPS: you would actually need to manipulate the real world. It would also take a considerable amount of time.
Come, let us hasten to a higher plane
Where dyads tread the fairy fields of Venn,
Their indices bedecked from one to n
Commingled in an endless Markov chain!
Come, every frustum longs to be a cone
And every vector dreams of matrices.
Hark to the gentle gradient of the breeze:
It whispers of a more ergodic zone.
In Riemann, Hilbert or in Banach space
Let superscripts and subscripts go their ways.
Our asymptotes no longer out of phase,
We shall encounter, counting, face to face.
I'll grant thee random access to my heart,
Thou'lt tell me all the constants of thy love;
And so we two shall all love's lemmas prove,
And in our bound partition never part.
For what did Cauchy know, or Christoffel,
Or Fourier, or any Boole or Euler,
Wielding their compasses, their pens and rulers,
Of thy supernal sinusoidal spell?
Cancel me not - for what then shall remain?
Abscissas some mantissas, modules, modes,
A root or two, a torus and a node:
The inverse of my verse, a null domain.
Ellipse of bliss, converge, O lips divine!
the product of four scalars it defines!
Cyberiad draws nigh, and the skew mind
Cuts capers like a happy haversine.
I see the eigenvalue in thine eye,
I hear the tender tensor in thy sigh.
Bernoulli would have been content to die,
Had he but known such a^2 cos 2 phi!
These genuinely are small, portable, and genuinely fuse hydrogen atoms in an entirely unkooky way. (They're produced industrially as neutron sources.)
Alas, it seems doubtful that they'll ever be useful as power sources, due to the design, but hot damn, with a bit of knowledge and some TV repair equipment you can build one yourself.
(You know, I suspect sometimes that the big fusion research programmes are, one day, finally going to build a working fusion power plant... and at roughly the same time, one of these alternative approaches will finally work and do exactly the same thing.)
Actually, it's an ARM7
on
A .Net CPU
·
· Score: 4, Interesting
According to the products page on their website:
384K of SRAM, single cycle access
27 MHz ARM7TDMI
FBGA chip form
~450,000 instructions per second
4MB non volatile flash
1.8-volt core, 3.3-volt I/O
32768 Hz real-time clock
32-pin pinout, including 24 GPIO ports multiplexed with other functions (8 VTU ports, dual serial ports, SPI, and USB port)
SPI and I2C interfaces
I assume FBGA is a typo for FPGA. This thing sounds suspiciously similar to one of those standard FPGAs with a built-in ARM7 core.
It actually sounds like quite a nice little embedded system, a kind of grown-up Basic STAMP. I expect that the.net VM is in ROM; on start-up the FPGA is probably bootstrapped from it. I wonder if it would be possible to replace it with a real operating system?
In my opiniation, "burglarize" is a perfectionally validative wordification. How else would reportization of the securitial/policial forceship appearize to be importantive enoughly to be respectative by the massmediaship and influentate the societyness?
For email outside the company surely S/MIME has captured the market.
Has it?
I've never seen an S/MIME message, or ever felt the need to make one, or get a key, or anything. In most of the (admittedly geeky) places where it's common to sign message, it's always been GPG. The company I work for uses GPG to communicate with customers, and the customers have never suggested using S/MIME instead. As far as I've seen, GPG (and PGP) rule.
So what exactly goes through the person's mind when they are moving the cursor. Do they just think "Left" and "Right" etc. Or do they simply have to look in the direction they want the cursor to go? It'd be interesting to try it out. It would bring me one step closer to utilizing the power of the force.
The way these things work, if they're anything like the similar systems I've read about in the past, is that you learn to change your brainwave patterns in a way that the computer can detect.
When you get hooked up to one, there's a long training session (like, weeks) where you spend a lot of time staring at a jittering cursor. After a while you learn the sort of mental attitude required to make it go one way, and the different one to make it another way. Actually assuming the attitude requires concentration and a little time. You get your feedback from watching the screen. The operative words here are crude and slow: the Matrix it ain't.
This system seems to be multidimensional, but I don't imagine they've managed to improve the speed. You'd still be far better off just reaching out and pressing a key.
If I were just starting to code, I'd probably use Kdevelop. However, I found over the course of a couple of painful days that I'm too dependent on some features of emacs to make the switch worthwhile. Quick searching. Tab indentation. Keyboard split buffers. Mouseless cut and paste.
Ditto, ditto, ditto, except in my case it's with vim.
I'd love to be able to use vim inside kdevelop. I'm actually a bit better off than you are, because there's a vim kpart, so it's theoretically possible to do: except whenever I actually tried it, it always died horribly.
Maybe someone needs to come up with a good way of abstracting the text editor part of an application from the actual application logic, to make this kind of thing easy. However, I suspect that that would involve rewriting kdevelop, vim and emacs, so I doubt it'll ever happen.
My TBird does it "by default", which probably means I set it circa v0.3 and it's been the same ever since! However, this looks like what you're after.
Thanks, but... locales. Oh my gawd. If there's one thing Linux does really badly, it's locales.
Yeah, I know I could just change LANG to en_GB, but then half my scripts stop working because upperlower case mappings change. Yeah, I know that it's really a problem with the scripts, but... it'll still stop them working. Sigh.
I'll try setting LC_TIME and see if that helps. Thanks again.
Trying to dim fluorescent lamps is a really problematic process; see here for a discussion. You can't dim them by reducing the voltage, and have to pulse the power supply instead. This will, as you have discovered, interact oddly with the ballast and the tube itself and is probably what's making the bulk of your radio noise.
(The article mentions a number of problems, including the fact that you might be significantly reducing the lifetime of your tubes by dimming them. YMMV.)
What I have in my living room are some long-live fluorescents to provide the bulk of the light, and some incandescents to change the colour and make the illumination more interesting. You might be able to do something similar without having to hook the tubes themselves up to the dimmer.
I use Thunderbird at home. I think it's great. I do think kmail is better, and I use that at work, but Thunderbird is still damn good.
There's just one thing I don't know how to do: Thunderbird displays all dates in the bizarre M/D/Y format. Is there any way I can persuade it do display them in either D/M/Y, which is more common in this country, or in Y/M/D, which is the preferred format everywhere? There seem to be no localisation options.
this seems like it's really just incremental progress.
Of course. Incremental progress is what gave Russia the Soyuz, the cheapest, most reliable man-rated spacecraft in the world. Incremental progress is good if you want to put humans on board. (Won't the Klipper end up carrying the same number of people as the Shuttle?)
The place to start playing with radical new technologies is with unmanned vehicles. If one of those blows up, nobody cares but the accountants.
Apache takes >15 seconds to start? My god man, what are you running?
A P133 notebook with 48MB of RAM.
So you can probably understand why I'm anxious to keep memory usage down! And yes, I know I should upgrade it, but it's harder than you might think. While I do have 128MB of laptop memory in hand, the blasted notebook can't handle DIMMs larger than 16MB. (It's got two 16MB DIMMs, plus another 16MB internally.)
There are two main reasons for using such an underpowered machine: firstly, cost, and secondly, it's an exercise in doing things the Unix Way. A P133 provides ample CPU power for doing simple stuff like serving web pages, processing email, etc. After all, it wasn't very long ago that this computer would be considered a number-crunching powerhouse. It's just a matter of utilising that CPU power appropriately. Finding the right software to run on it has led me to find all kinds of interesting, lightweight, flexible tools: thttpd serves my web pages, sn does NNTP, dnsmasq does DNS, etc. The only big server I still have is exim --- I'm on the lookout for a smaller replacement.
Apache on this machine was noteably sluggish just serving pages; whenever a mail came in, big chunks of Apache would get swapped out and then have to be swapped back in again to emit the next page. This doesn't happen with thttpd.
Also, I just find thttpd appeals to me far more than Apache. Apache's this vast amorphous blob of a program, which can do anything and everything by absorbing plugins. thttpd is small and optimised to do one thing well, and it does it really well.
Sometimes I really hate comments like this. Just how heavy to you think Apache is? With PHP/Perl/Python/Kitchensink support loaded in, sure.
Stock Apache on my server came in at about 5-10MB RSS. thttpd is currently ticking away at 976kB. Apache takes >15s to start, thttpd starts instantly. Apache is too heavyweight for me. (My server is grossly underpowered, yes, but size and budget constraints mean I can't upgrade it.)
Now then, on to WebDAV. Your comment, "Are there any small, light tools that will just do WebDAV and nothing else, that I can add to my setup?" belies a fundamental ignorance of what WebDAV is. It's an HTTP layer for file handling.
Yes, using a very specialised subset of HTTP extensions. It'd be entirely possible, and extremely useful, to write a special-purpose HTTP server that just did WebDAV. That would also be a useful distinction of functionality: a stock HTTP server doesn't need to write to files, but a WebDAV server would, which means it'd be easier to security audit everything.
I think the biggest problem is that you're approaching the problem for a different direction than I am. I want lightweight, low footprint, but not necessarily fast. It is a home setup, after all. You seem to be looking for something that can server vast amounts of traffic scalably.
Does anyone know where I can find a small, simple WebDAV server that's doesn't require something as heavyweight as Apache?
My main server is a low-end notebook. It passes packets, does SMTP, file serving etc quite nicely. Unfortunately apache is just way too heavyweight for it; I use thttpd instead, which is smaller and faster.
I'd like to set up a WebDAV server. But I don't want to have to replace thttpd. Are there any small, light tools that will just do WebDAV and nothing else, that I can add to my setup?
the only thing you have no control over with a DVD is the intro sequence, where you are often forced to sit through the FBI/Interpol warning...
My DVD player, a cheap far eastern thing, has a cunning feature where if you insert a disk, press STOP twice while the intro is playing and then press PLAY, on about 90% of disks it'll immediately start playing title 1. It misses the intro, the warnings, the menus, everything. It's great.
Region hackable, too --- they know where the money is.
That vase has to be uranium glass. Sometimes called vaseline glass. Hold a GM counter next to it.
It's not, it's very good lead crystal.
My father actually had one of those uranium salt vases. He was a physics teacher at an old school, and they had all kinds of interesting stuff tucked away in the cupboards. At one point he went through with a Geiger counter and dug out all the radioactive sources, and lined them up on the bench in order of intensity.
The vase, which was a gorgeous colour, came somewhere in the middle, next to the lump of pitchblende (uranium ore). At the bottom, just below the americium smoke detector, was the official issue radioactive source for schools. At the top was something that was so radioactive he handled it with tongs: a WWII-era aircraft instrument dial, painted with luminous radium paint. Aaaah!
As for skin cancer rates... got any references? I'd expect that that applies mostly to people who work under them, in places where there are banks of those old-fashioned two-metre tubes. Home flourescents use miniature coiled-up tubes that fit into the space a bulb normally takes. I'd expect those to produce a tiny fraction of the UV output.
The site's slashdotted, so I can't actually go and see what they've got, but I know that in the past white LEDs had problems because they don't do white very well. I wonder if they've managed to solve them...
Flourescent lamps work by using a mercury vapour discharge tube to produce ultraviolet light, which excites a phosphor coated on the inside of the tube to produce white light of various colours. They work pretty well; my house pretty much only uses 22W flourescent bulbs, which are roughly equivalent to 100W incandescents. The colour's not bad, but the spectrum is a bit weird, and some things look a little strange. (My parents have a glass vase that shows up purple under sunlight or incandescent light, but green under flourescent light.)
White LEDs can use the same system, with a UV LED that excites phosphor, but these are inefficient and very expensive. (Or at least were, the last time I looked.) A more common way is to use a red, green and blue LED in the same package. These can be cool because you can change the colour by simply changing the relative brightnesses, but they produce a spectrum that makes flourescent tubes look normal. Compared to incandescents, they're very blue, and some things look really strange.
...the top of the elevator has to be in geostationary orbit, because the entire elevator is attached to the ground. The moon rotates once every thirty days. You can calculate, using this equation:
...the height of the elevator, therefore; for the moon it's 190000km. In other words, five times higher than one on Earth! That's nearly half-way to Earth; the gravitational disturbances from Earth's much greater mass could well make the whole thing infeasible.
Detection parameters?
on
MiniGRAIL Online
·
· Score: 5, Interesting
Since this thing is fundamentally a gravity wave antenna, what's the range of frequencies it can usefully detect? Is it just limited to 2.9kHz waves (plus or minus 115Hz)? What about harmonics? Could it be tuned for other frequencies or would that require a redesign?
The reason I ask is that not only does this thing have immense cool value, similar detectors might be very handy for SETI. We know practically nothing about the gravity wave spectrum; it's perfectly possible that the reason we can't find any alien communications with radio telescopes is because everybody's communicating with gravity waves.
So I'm eager to find out what this thing is capable of seeing.
Incidentally, I'm getting slightly disturbed how similar modern gravity wave detectors are getting to those described in David Brin's Earth. If anyone invents a strange new form of physics for manipulating singularities called cavitronics, I for one wish to emigrate to Mars.
Suppose you wanted something that didn't expand or contract in certain temperature ranges, you might be able to combine something with negative expansion and positive expansion in a structure so that the entire structure doesn't expand or contract.
Clockmakers have used such a material for a long time; it's a complex alloy called invar. The linked article gives the composition of one type of invar, which has an expansion coefficient of 1.6 ppm. This means that a bar of invar ten kilometres long that heats up by one kelvin will get longer by 1.6cm. That's pretty good. The equivalent steel bar would expand by 11cm.
And yeah, the above figures were very nearly copied verbatim from the article; read it if you're interested.
Slashdot Mirror
Freespace II r0xx0rs.
It was obviously written by someone who practically worshipped X-Wing and Tie Fighter, because the game mechanics are identical. Completely. Oh, everything has different names, but when you get presented with a new weapon that fires fat blue bolts of energy that can disable a ship without damaging it, you know it's an ion cannon.
It also runs on modern hardware, or at least modern-ish (it runs beautifully on my GeForce II), and looks beautiful. It has big explosions, and glowing red nebulae that are genuinely disorienting to fly through, and complex ships, and it's got some capital ships that are almost beyond belief: they take minutes to fly round. Really.
If there's anything wrong with it, it's that it's damned hard, and that the storyline just doesn't grab me. Tie Fighter (never played X-Wing --- die, rebel scum!) borrowed off the epic Star Wars story. Freespace hasn't, which means it has to work much harder, and I don't think it quite manages to pull it off.
You know what? I'd love to see a total conversion for Freespace 2 that remade Tie Fighter. Now, that would be a good game.
(I'd heard that Freespace 2 had fallen into a legal hole that meant that nobody owned it, and so was legal to download. It seems unlikely to me, but does anyone know anything about it?)
Galileo, OTOH, is not owned by the US, and it strikes me that it's extremely unlikely that the US government will ever get root on the Galileo satellite network. Therefore, disabling Galileo for a particular area would require brute force approaches: physical destruction of the satellites, which would have knock-on political effects that I would hope even Bush would balk at, or else on-the-spot jammers.
Either way, preventing a rogue state like, say, Canada from access to Galileo would require significantly more committment than with GPS: you would actually need to manipulate the real world. It would also take a considerable amount of time.
Yeah, but where do you get depleted uranium? Forget making bombs, I just want some as a paperweight... but it's a little hard to come by these days.
http://en.wikipedia.org/wiki/Farnsworth-Hirsch_Fus or
These genuinely are small, portable, and genuinely fuse hydrogen atoms in an entirely unkooky way. (They're produced industrially as neutron sources.)
Alas, it seems doubtful that they'll ever be useful as power sources, due to the design, but hot damn, with a bit of knowledge and some TV repair equipment you can build one yourself.
(You know, I suspect sometimes that the big fusion research programmes are, one day, finally going to build a working fusion power plant... and at roughly the same time, one of these alternative approaches will finally work and do exactly the same thing.)
I assume FBGA is a typo for FPGA. This thing sounds suspiciously similar to one of those standard FPGAs with a built-in ARM7 core.
It actually sounds like quite a nice little embedded system, a kind of grown-up Basic STAMP. I expect that the .net VM is in ROM; on start-up the FPGA is probably bootstrapped from it. I wonder if it would be possible to replace it with a real operating system?
George! You finally got a Slashdot account!
Has it?
I've never seen an S/MIME message, or ever felt the need to make one, or get a key, or anything. In most of the (admittedly geeky) places where it's common to sign message, it's always been GPG. The company I work for uses GPG to communicate with customers, and the customers have never suggested using S/MIME instead. As far as I've seen, GPG (and PGP) rule.
Where is S/MIME actually used?
Three lawyers walk in to a bar.
Really, your honour. That's exactly the way it happened. I was just holding it at the time. I had no idea they would come round that corner...
The way these things work, if they're anything like the similar systems I've read about in the past, is that you learn to change your brainwave patterns in a way that the computer can detect.
When you get hooked up to one, there's a long training session (like, weeks) where you spend a lot of time staring at a jittering cursor. After a while you learn the sort of mental attitude required to make it go one way, and the different one to make it another way. Actually assuming the attitude requires concentration and a little time. You get your feedback from watching the screen. The operative words here are crude and slow: the Matrix it ain't.
This system seems to be multidimensional, but I don't imagine they've managed to improve the speed. You'd still be far better off just reaching out and pressing a key.
I've just had the mental image of a guy in plate armor with neon stripes and sunglasses --- the Knight Who Screams 'Im!'
Need caffeine. Must have caffeine...
Ditto, ditto, ditto, except in my case it's with vim.
I'd love to be able to use vim inside kdevelop. I'm actually a bit better off than you are, because there's a vim kpart, so it's theoretically possible to do: except whenever I actually tried it, it always died horribly.
Maybe someone needs to come up with a good way of abstracting the text editor part of an application from the actual application logic, to make this kind of thing easy. However, I suspect that that would involve rewriting kdevelop, vim and emacs, so I doubt it'll ever happen.
Thanks, but... locales. Oh my gawd. If there's one thing Linux does really badly, it's locales.
Yeah, I know I could just change LANG to en_GB, but then half my scripts stop working because upperlower case mappings change. Yeah, I know that it's really a problem with the scripts, but... it'll still stop them working. Sigh.
I'll try setting LC_TIME and see if that helps. Thanks again.
(The article mentions a number of problems, including the fact that you might be significantly reducing the lifetime of your tubes by dimming them. YMMV.)
What I have in my living room are some long-live fluorescents to provide the bulk of the light, and some incandescents to change the colour and make the illumination more interesting. You might be able to do something similar without having to hook the tubes themselves up to the dimmer.
There's just one thing I don't know how to do: Thunderbird displays all dates in the bizarre M/D/Y format. Is there any way I can persuade it do display them in either D/M/Y, which is more common in this country, or in Y/M/D, which is the preferred format everywhere? There seem to be no localisation options.
Of course. Incremental progress is what gave Russia the Soyuz, the cheapest, most reliable man-rated spacecraft in the world. Incremental progress is good if you want to put humans on board. (Won't the Klipper end up carrying the same number of people as the Shuttle?)
The place to start playing with radical new technologies is with unmanned vehicles. If one of those blows up, nobody cares but the accountants.
A P133 notebook with 48MB of RAM.
So you can probably understand why I'm anxious to keep memory usage down! And yes, I know I should upgrade it, but it's harder than you might think. While I do have 128MB of laptop memory in hand, the blasted notebook can't handle DIMMs larger than 16MB. (It's got two 16MB DIMMs, plus another 16MB internally.)
There are two main reasons for using such an underpowered machine: firstly, cost, and secondly, it's an exercise in doing things the Unix Way. A P133 provides ample CPU power for doing simple stuff like serving web pages, processing email, etc. After all, it wasn't very long ago that this computer would be considered a number-crunching powerhouse. It's just a matter of utilising that CPU power appropriately. Finding the right software to run on it has led me to find all kinds of interesting, lightweight, flexible tools: thttpd serves my web pages, sn does NNTP, dnsmasq does DNS, etc. The only big server I still have is exim --- I'm on the lookout for a smaller replacement.
Apache on this machine was noteably sluggish just serving pages; whenever a mail came in, big chunks of Apache would get swapped out and then have to be swapped back in again to emit the next page. This doesn't happen with thttpd.
Also, I just find thttpd appeals to me far more than Apache. Apache's this vast amorphous blob of a program, which can do anything and everything by absorbing plugins. thttpd is small and optimised to do one thing well, and it does it really well.
Stock Apache on my server came in at about 5-10MB RSS. thttpd is currently ticking away at 976kB. Apache takes >15s to start, thttpd starts instantly. Apache is too heavyweight for me. (My server is grossly underpowered, yes, but size and budget constraints mean I can't upgrade it.) Now then, on to WebDAV. Your comment, "Are there any small, light tools that will just do WebDAV and nothing else, that I can add to my setup?" belies a fundamental ignorance of what WebDAV is. It's an HTTP layer for file handling.
Yes, using a very specialised subset of HTTP extensions. It'd be entirely possible, and extremely useful, to write a special-purpose HTTP server that just did WebDAV. That would also be a useful distinction of functionality: a stock HTTP server doesn't need to write to files, but a WebDAV server would, which means it'd be easier to security audit everything.
I think the biggest problem is that you're approaching the problem for a different direction than I am. I want lightweight, low footprint, but not necessarily fast. It is a home setup, after all. You seem to be looking for something that can server vast amounts of traffic scalably.
My main server is a low-end notebook. It passes packets, does SMTP, file serving etc quite nicely. Unfortunately apache is just way too heavyweight for it; I use thttpd instead, which is smaller and faster.
I'd like to set up a WebDAV server. But I don't want to have to replace thttpd. Are there any small, light tools that will just do WebDAV and nothing else, that I can add to my setup?
My DVD player, a cheap far eastern thing, has a cunning feature where if you insert a disk, press STOP twice while the intro is playing and then press PLAY, on about 90% of disks it'll immediately start playing title 1. It misses the intro, the warnings, the menus, everything. It's great.
Region hackable, too --- they know where the money is.
It's not, it's very good lead crystal.
My father actually had one of those uranium salt vases. He was a physics teacher at an old school, and they had all kinds of interesting stuff tucked away in the cupboards. At one point he went through with a Geiger counter and dug out all the radioactive sources, and lined them up on the bench in order of intensity.
The vase, which was a gorgeous colour, came somewhere in the middle, next to the lump of pitchblende (uranium ore). At the bottom, just below the americium smoke detector, was the official issue radioactive source for schools. At the top was something that was so radioactive he handled it with tongs: a WWII-era aircraft instrument dial, painted with luminous radium paint. Aaaah!
As for skin cancer rates... got any references? I'd expect that that applies mostly to people who work under them, in places where there are banks of those old-fashioned two-metre tubes. Home flourescents use miniature coiled-up tubes that fit into the space a bulb normally takes. I'd expect those to produce a tiny fraction of the UV output.
Flourescent lamps work by using a mercury vapour discharge tube to produce ultraviolet light, which excites a phosphor coated on the inside of the tube to produce white light of various colours. They work pretty well; my house pretty much only uses 22W flourescent bulbs, which are roughly equivalent to 100W incandescents. The colour's not bad, but the spectrum is a bit weird, and some things look a little strange. (My parents have a glass vase that shows up purple under sunlight or incandescent light, but green under flourescent light.)
White LEDs can use the same system, with a UV LED that excites phosphor, but these are inefficient and very expensive. (Or at least were, the last time I looked.) A more common way is to use a red, green and blue LED in the same package. These can be cool because you can change the colour by simply changing the relative brightnesses, but they produce a spectrum that makes flourescent tubes look normal. Compared to incandescents, they're very blue, and some things look really strange.
Does anyone actually know what these things are?
orbital_radius^3 = (3,600^2 * surface_gravity * surface_radius^2 * orbital_period^2) / 2*pi^2
...the height of the elevator, therefore; for the moon it's 190000km. In other words, five times higher than one on Earth! That's nearly half-way to Earth; the gravitational disturbances from Earth's much greater mass could well make the whole thing infeasible.
The reason I ask is that not only does this thing have immense cool value, similar detectors might be very handy for SETI. We know practically nothing about the gravity wave spectrum; it's perfectly possible that the reason we can't find any alien communications with radio telescopes is because everybody's communicating with gravity waves.
So I'm eager to find out what this thing is capable of seeing.
Incidentally, I'm getting slightly disturbed how similar modern gravity wave detectors are getting to those described in David Brin's Earth. If anyone invents a strange new form of physics for manipulating singularities called cavitronics, I for one wish to emigrate to Mars.
Clockmakers have used such a material for a long time; it's a complex alloy called invar. The linked article gives the composition of one type of invar, which has an expansion coefficient of 1.6 ppm. This means that a bar of invar ten kilometres long that heats up by one kelvin will get longer by 1.6cm. That's pretty good. The equivalent steel bar would expand by 11cm.
And yeah, the above figures were very nearly copied verbatim from the article; read it if you're interested.