...rippling bands across the ground from atmospheric turbulence, razor-sharp shadows everywhere, with prominent diffraction rings around the ones from faraway objects. And a flaming rainbow streak, blue at the top, shading down through green to red, as it rises or sets in a clear sky.
If my calculations are right, it won't burn your eyes; it would be roughly equivalent to looking into a 4-microwatt laser, not nearly strong enough to be dangerous. A 10-inch telescope could collimate it into a 5-mW beam, bright enough to see passing through the air, if only it were dark outside. The Palomar reflector would collect closer to 2 watts, enough to start fires and such.
If it happened this month, most everybody north of the Antarctic Circle would be cruelly cheated. Any time from August through April, though, it should be visible in the night sky from just about anywhere but that same Antarctic. And yes, I'd be willing to drag myself out of bed pre-dawn for this.
If you must obsessively collect something, it might as well be bits. Every year or two, you can squeeze twice as much stuff into the same space. That makes it less likely that you'll be found trapped, filthy and emaciated, beneath a collapsed pile of your hoarded treasures.
This is the first time in human history that true exponential hoarding has become not only possible, but practical.
And thank you for the survey, although I'm afraid I'm still not its target audience. (First, I need a definition of "symplectic integrator". Hmm. Works on diffeq's related to "symplectic geometry", which studies "symplectic manifolds", which are differentiable (hooray! A word I understand!) and have a closed (ok, maybe), non-degenerate (yeah) "2-form", which is apparently "the 2nd exterior power of the cotangent bundle of the manifold". By paying close attention to my body's signals over the years, I've learned to recognize this feeling as "you've read too far ahead in the textbook again".
P.S. to moderator number 2: "Redundant"? Really? Providing information from a not-freely-available article that directly responds to a specific question is "redundant"? Ooo-kay. Guess I don't have quite so good a handle on this "moderation" thing as I thought.
Also, please explain how using a telescope magically invalidates light pollution. If I follow your line of reasoning, I should be able to use a pair of binoculars to get a crystal clear view out of a dirty window.
You're right that the "bottom of a well" claim is bogus, but you miss the boat in this last paragraph.
A telescope collects more light than the naked eye, and it also magnifies the image of what you're seeing. If you're looking at an extended object -- a nebula, a planet, or a patch of light-polluted sky -- this magnification spreads the object's light over a wider area, making it dimmer. Stars, though, are still effectively point sources, so they just look brighter.
So, looking for stars in a light-polluted sky is easier with a telescope, because it makes the stars appear brighter relative to their background. With nebulae, comets, or other extended objects, especially where the object's apparent brightness doesn't exceed the sky's apparent brightness, the telescope doesn't help much at all.
As for the binoculars and the dirty window, well, the dirt would be out-of-focus for the binoculars, so they might help a little. Mostly, though, the analogy is a poor fit. Light pollution is effectively radiating from clear sky, not blocking light as smog or clouds would do.
Here's a straight copy of the description, since I know almost nothing about the domain it's describing:
The model for the integration of the planetary orbits is derived from the La2004 model9 that was integrated over 250 Myr for the study of the palaeoclimates of the Earth and Mars9, 12. It comprises the eight major planets and Pluto and includes relativistic13 and averaged lunar contributions14 (Supplementary Information). We used the SABA4 symplectic integrator15, which is adapted to perturbed Hamiltonian systems. The step size is 2.5x10^-2 years, unless the eccentricity of the planets increases beyond about 0.4, in which case the step size is reduced to preserve numerical accuracy.
It has been established that, owing to the proximity of a resonance with Jupiter, Mercury's eccentricity can be pumped to values large enough to allow collision with Venus within 5 Gyr (refs 1â"3). This conclusion, however, was established either with averaged equations1, 2 that are not appropriate near the collisions or with non-relativistic models in which the resonance effect is greatly enhanced by a decrease of the perihelion velocity of Mercury2, 3. In these previous studies, the Earth's orbit was essentially unaffected. Here we report numerical simulations of the evolution of the Solar System over 5 Gyr, including contributions from the Moon and general relativity.
The authors claim this is the first extended simulation set incorporating GR and avoiding the problematic averaging technique.
Um, no. Hot air balloons don't expand when you heat them up, otherwise the density of the air would remain at the external density and it wouldn't float. Notice how the hot breath you use when blowing up a balloon doesn't make it float.
Hot-air balloons typically don't expand during normal operation, but not for the reason you claim.
Build a balloon containing a kilo of air. Heat that air until it wants to be half its original density.
If you vent half a kilo of air, volume will remain constant, the remaining half-kilo will be displacing a kilo of air at its original density, and you'll get a half-kilo of lift.
If you don't vent any air, and keep volume constant (as you suggested above), PRESSURE will increase, but density (mass/volume) will remain constant, and you'll get no lift.
If you don't vent any air, but let volume increase, pressure will remain constant, volume will double, density (mass/volume) will drop by half, you'll be displacing two kilos of air at the original density, and you'll get a full kilo of lift.
Hot-air balloons typically get inflated to a more-or-less constant volume because it's easier to build a strong and durable balloon that works that way. Popping due to a pinprick is a bummer when you're at altitude and carrying passengers.
Though your dig against Apple for their slow to come Java updates is not unfounded, Apple won't be controlling OpenCL. You don't even need to read TFA or TFwiki, your parent poster says it.
Precisely. Remember, they didn't "control" Java, either.
Remember when Steve said that OS X was going to be the "best Java platform on the planet"? Well, there may have been some interval in which you could make that case. But if you're trying to run JOGL on a 2008 MacBook, or Eclipse under Java 6, or anything at all under Java 7, you tell me how well it's working out for you.
I've been a Mac user since 1985, and an OS X user since 2000. Still am. But Apple are building a pretty consistent track record of throwing their weight behind an emerging (or, in the case of Java, "established") standard, proclaiming their superior support, and then losing interest and wandering off in another direction.
They don't always do so, of course. I particularly hope they don't pull this trick with OpenCL, for a variety of reasons.
( Next item we need to add to the list of critically needed tech. Water purification and desalination that can be applied in the residential markets. Imagine how much land would open up for crops, settlement, and carbon sinking if we just had cheap and easy to deploy water desalination. )
You live in California, don't you?
I can say with some confidence that my residential area, well over 100 miles from the nearest ocean, is not in any sense bottlenecked on water desalination capacity.
I neglected to mention the point made by someone else just upthread -- the TouchStream, like the iPhone, can correct based on subsequent as well as preceding letters. So, if you type T-H-(R-but-almost-E)-E-A, the TouchStream might issue T-H-E-E-backspace-backspace-R-E-A.
And that's why vi (or emacs, or presumably WordStar) is a problem.
Does using such an auto-correcting keyboard make it harder to type correctly when you move to a "normal" keyboard? Something bothers me about devices that train me to make more unaware mistakes.
A little. But it's completely overwhelmed by the rich tactile feedback that you get from a physical keyboard. Without that tactile feedback, even the recovered-from-alien-spacecraft-level intelligence in the FingerWorks TouchStream keyboard only gets you up to about half the typing speed you see on a conventional keyboard; that, and the $300-400 price tag, made it a commercial failure.
But I'm much happier typing half as fast and having zero wrist pain. (No reaching for the mouse or modifier keys; they're both gestures, and don't even require you to move from the home position.)
When I do go back to a conventional keyboard, I sometimes make a few autocorrect-worthy mistakes in the first few minutes, but then I shift back into non-zero-force mode and they go away. My speed and accuracy on a conventional keyboard, while it's always been substandard, hasn't dropped since I've been using the TouchStream.
...based on the IP they acquired from FingerWorks. You can do really sophisticated error-correction if you're getting not only a stream of characters, but the exact location of the press, contact area, dwell time, and possibly more. So, with a virtual multi-touch keyboard, you can say "Okay, that looked like an R, but the contact was actually most of the way over toward E, and the previous two letters were T-H, so I'm going to go ahead and make it an E."
I know it'll rankle the manual-transmission crowd, but I've been using a FingerWorks keyboard for years, and most of the time, it's absolutely spooky how well the autocorrect works. (Just don't try high-intensity vi work.)
In fact you will often see today that a job that could be handled by a 555 and a couple of caps has been replaced with an internally-clocked microcontroller simply because it's a known platform and development is easy.
One microcontroller beats one special-function chip plus caps on part count, board space, power consumption, and probably cost. And it can take care of other odd jobs around the circuit as well.
Throwing every chat comment into a linear sequence certainly doesn't scale well for large conversations. Has anyone tried building chat into a tree, much like we see right here? It might tend to fragment conversations, but if the conversation gets too large, that's what's supposed to happen.
What I really want to see is something like the "decision duel" system from Marc Stiegler's David's Sling.
Yep, the 181 shows up in the layout diagram on his site. I'm a little surprised, actually -- if you compromise enough to use GALs (programmable logic), it's kind of pointless to brag about being "TTL-based". If I build something out of a fistful of PICs, and hook them together with TTL-level signals, can I claim the same thing?
I built a "video card" for a TRS-80 as a hobby project about 25 years ago -- 50 or so chips, 8 or 10 solderless breadboards, and a baking sheet for support/ground-plane. 30 rows, 100 columns, 8x16 pixels per character, memory-mapped, and the only thing that wasn't SS/MS-TTL was the RAM for the display buffer and the character lookup table. I guess I spent six months or so building it up piece-by-piece -- the bus interface, then the clock and divider chain, then the character RAM, then the display RAM, then the driver. I'm still kind of amazed that I pulled it off. I actually used the whole thing as a terminal for a year or two, because 100x30 was so much more pleasant than 64x16. And once I wrote a VT52 emulator and a serial driver that could keep up with a 1200-baud modem, I could actually do visual editing from my dorm room -- the height of luxury, I'm telling you.
...not subscription or service fees. When AT&T broke up, they generously offered to let me buy the phone I'd been using for something like $20, rather than turning it in. I think I actually took them up on it, and still have the thing in a closet somewhere, complete with rotary dial and acoustic-coupler-compatible handset.
Pick a small set of standards that will work "well enough" and let them become the Legacy Standard. I'm so sick of going to garage sales and seeing good equipment, such as printers and scanners, that won't connect to any computer that I own. I have a drawer full of PS/2 keyboards.
Okay. Would the "good enough" legacy graphics standard be VGA? Oops, you'll have to toss all your EGA, CGA, Hercules and NTSC/PAL monitors. For serial connectivity, you could provide a DB-9, and carry around a toolbox full of gender-swappers, null modems and 9-pin/25-pin/mini-DIN/RJ45 connectors like your father did. For parallel, there's a "standard" of sorts that's still commonly seen -- but do you remember how to connect it to a Centronics 737? Oh, and don't forget the DB-15 for Ethernet transceivers -- I paid good money for all this thicknet, and there's no way I'm tossing it just because this newfangled twisted-pair stuff has 100 times the capacity.
Maybe instead of an optical drive, your laptop can have a pop-out shelf bearing an array of different connectors. You could even put some DIP sockets on the bottom so your old 16K RAM chips don't have to go to waste.
Slashdot Mirror
...rippling bands across the ground from atmospheric turbulence, razor-sharp shadows everywhere, with prominent diffraction rings around the ones from faraway objects. And a flaming rainbow streak, blue at the top, shading down through green to red, as it rises or sets in a clear sky.
If my calculations are right, it won't burn your eyes; it would be roughly equivalent to looking into a 4-microwatt laser, not nearly strong enough to be dangerous. A 10-inch telescope could collimate it into a 5-mW beam, bright enough to see passing through the air, if only it were dark outside. The Palomar reflector would collect closer to 2 watts, enough to start fires and such.
If it happened this month, most everybody north of the Antarctic Circle would be cruelly cheated. Any time from August through April, though, it should be visible in the night sky from just about anywhere but that same Antarctic. And yes, I'd be willing to drag myself out of bed pre-dawn for this.
If you must obsessively collect something, it might as well be bits. Every year or two, you can squeeze twice as much stuff into the same space. That makes it less likely that you'll be found trapped, filthy and emaciated, beneath a collapsed pile of your hoarded treasures.
This is the first time in human history that true exponential hoarding has become not only possible, but practical.
And thank you for the survey, although I'm afraid I'm still not its target audience. (First, I need a definition of "symplectic integrator". Hmm. Works on diffeq's related to "symplectic geometry", which studies "symplectic manifolds", which are differentiable (hooray! A word I understand!) and have a closed (ok, maybe), non-degenerate (yeah) "2-form", which is apparently "the 2nd exterior power of the cotangent bundle of the manifold". By paying close attention to my body's signals over the years, I've learned to recognize this feeling as "you've read too far ahead in the textbook again".
P.S. to moderator number 2: "Redundant"? Really? Providing information from a not-freely-available article that directly responds to a specific question is "redundant"? Ooo-kay. Guess I don't have quite so good a handle on this "moderation" thing as I thought.
Also, please explain how using a telescope magically invalidates light pollution. If I follow your line of reasoning, I should be able to use a pair of binoculars to get a crystal clear view out of a dirty window.
You're right that the "bottom of a well" claim is bogus, but you miss the boat in this last paragraph.
A telescope collects more light than the naked eye, and it also magnifies the image of what you're seeing. If you're looking at an extended object -- a nebula, a planet, or a patch of light-polluted sky -- this magnification spreads the object's light over a wider area, making it dimmer. Stars, though, are still effectively point sources, so they just look brighter.
So, looking for stars in a light-polluted sky is easier with a telescope, because it makes the stars appear brighter relative to their background. With nebulae, comets, or other extended objects, especially where the object's apparent brightness doesn't exceed the sky's apparent brightness, the telescope doesn't help much at all.
As for the binoculars and the dirty window, well, the dirt would be out-of-focus for the binoculars, so they might help a little. Mostly, though, the analogy is a poor fit. Light pollution is effectively radiating from clear sky, not blocking light as smog or clouds would do.
Here's a straight copy of the description, since I know almost nothing about the domain it's describing:
The model for the integration of the planetary orbits is derived from the La2004 model9 that was integrated over 250 Myr for the study of the palaeoclimates of the Earth and Mars9, 12. It comprises the eight major planets and Pluto and includes relativistic13 and averaged lunar contributions14 (Supplementary Information). We used the SABA4 symplectic integrator15, which is adapted to perturbed Hamiltonian systems. The step size is 2.5x10^-2 years, unless the eccentricity of the planets increases beyond about 0.4, in which case the step size is reduced to preserve numerical accuracy.
9. Laskar, J. et al. A long term numerical solution for the insolation quantities of the Earth. Astron. Astrophys. 428, 261-285 (2004)
12. Laskar, J. et al. Long term evolution and chaotic diffusion of the insolation quantities of Mars. Icarus 170, 343-364 (2004)
13. Saha, P. & Tremaine, S. Long-term planetary integration with individual time steps. Astron. J. 108, 1962-1969 (1994)
14. Boué, G. & Laskar, J. Precession of a planet with a satellite. Icarus 196, 1-15 (2008)
15. Laskar, J. & Robutel, P. High order symplectic integrators for perturbed Hamiltonian systems. Celest. Mech. Dynam. Astron. 80, 39-62 (2001)
From TFAbstract, helpfully linked downstream:
It has been established that, owing to the proximity of a resonance with Jupiter, Mercury's eccentricity can be pumped to values large enough to allow collision with Venus within 5 Gyr (refs 1â"3). This conclusion, however, was established either with averaged equations1, 2 that are not appropriate near the collisions or with non-relativistic models in which the resonance effect is greatly enhanced by a decrease of the perihelion velocity of Mercury2, 3. In these previous studies, the Earth's orbit was essentially unaffected. Here we report numerical simulations of the evolution of the Solar System over 5 Gyr, including contributions from the Moon and general relativity.
The authors claim this is the first extended simulation set incorporating GR and avoiding the problematic averaging technique.
This could be even better than the "bass-seeking missile" that I've wanted to deploy for years.
Um, no. Hot air balloons don't expand when you heat them up, otherwise the density of the air would remain at the external density and it wouldn't float. Notice how the hot breath you use when blowing up a balloon doesn't make it float.
Hot-air balloons typically don't expand during normal operation, but not for the reason you claim.
Build a balloon containing a kilo of air. Heat that air until it wants to be half its original density.
If you vent half a kilo of air, volume will remain constant, the remaining half-kilo will be displacing a kilo of air at its original density, and you'll get a half-kilo of lift.
If you don't vent any air, and keep volume constant (as you suggested above), PRESSURE will increase, but density (mass/volume) will remain constant, and you'll get no lift.
If you don't vent any air, but let volume increase, pressure will remain constant, volume will double, density (mass/volume) will drop by half, you'll be displacing two kilos of air at the original density, and you'll get a full kilo of lift.
Hot-air balloons typically get inflated to a more-or-less constant volume because it's easier to build a strong and durable balloon that works that way. Popping due to a pinprick is a bummer when you're at altitude and carrying passengers.
Though your dig against Apple for their slow to come Java updates is not unfounded, Apple won't be controlling OpenCL. You don't even need to read TFA or TFwiki, your parent poster says it.
Precisely. Remember, they didn't "control" Java, either.
Remember when Steve said that OS X was going to be the "best Java platform on the planet"? Well, there may have been some interval in which you could make that case. But if you're trying to run JOGL on a 2008 MacBook, or Eclipse under Java 6, or anything at all under Java 7, you tell me how well it's working out for you.
I've been a Mac user since 1985, and an OS X user since 2000. Still am. But Apple are building a pretty consistent track record of throwing their weight behind an emerging (or, in the case of Java, "established") standard, proclaiming their superior support, and then losing interest and wandering off in another direction.
They don't always do so, of course. I particularly hope they don't pull this trick with OpenCL, for a variety of reasons.
I hope they do a better job supporting this framework than they've done with Java.
( Next item we need to add to the list of critically needed tech. Water purification and desalination that can be applied in the residential markets. Imagine how much land would open up for crops, settlement, and carbon sinking if we just had cheap and easy to deploy water desalination. )
You live in California, don't you?
I can say with some confidence that my residential area, well over 100 miles from the nearest ocean, is not in any sense bottlenecked on water desalination capacity.
...here's a towel.
I neglected to mention the point made by someone else just upthread -- the TouchStream, like the iPhone, can correct based on subsequent as well as preceding letters. So, if you type T-H-(R-but-almost-E)-E-A, the TouchStream might issue T-H-E-E-backspace-backspace-R-E-A.
And that's why vi (or emacs, or presumably WordStar) is a problem.
Does using such an auto-correcting keyboard make it harder to type correctly when you move to a "normal" keyboard? Something bothers me about devices that train me to make more unaware mistakes.
A little. But it's completely overwhelmed by the rich tactile feedback that you get from a physical keyboard. Without that tactile feedback, even the recovered-from-alien-spacecraft-level intelligence in the FingerWorks TouchStream keyboard only gets you up to about half the typing speed you see on a conventional keyboard; that, and the $300-400 price tag, made it a commercial failure.
But I'm much happier typing half as fast and having zero wrist pain. (No reaching for the mouse or modifier keys; they're both gestures, and don't even require you to move from the home position.)
When I do go back to a conventional keyboard, I sometimes make a few autocorrect-worthy mistakes in the first few minutes, but then I shift back into non-zero-force mode and they go away. My speed and accuracy on a conventional keyboard, while it's always been substandard, hasn't dropped since I've been using the TouchStream.
And you could put little springs under the bumps, so that you could feel them move when you pressed them hard enough!
...based on the IP they acquired from FingerWorks. You can do really sophisticated error-correction if you're getting not only a stream of characters, but the exact location of the press, contact area, dwell time, and possibly more. So, with a virtual multi-touch keyboard, you can say "Okay, that looked like an R, but the contact was actually most of the way over toward E, and the previous two letters were T-H, so I'm going to go ahead and make it an E."
I know it'll rankle the manual-transmission crowd, but I've been using a FingerWorks keyboard for years, and most of the time, it's absolutely spooky how well the autocorrect works. (Just don't try high-intensity vi work.)
What, you think you know better than MICROSOFT what should be on your machine?
In fact you will often see today that a job that could be handled by a 555 and a couple of caps has been replaced with an internally-clocked microcontroller simply because it's a known platform and development is easy.
One microcontroller beats one special-function chip plus caps on part count, board space, power consumption, and probably cost. And it can take care of other odd jobs around the circuit as well.
Throwing every chat comment into a linear sequence certainly doesn't scale well for large conversations. Has anyone tried building chat into a tree, much like we see right here? It might tend to fragment conversations, but if the conversation gets too large, that's what's supposed to happen.
What I really want to see is something like the "decision duel" system from Marc Stiegler's David's Sling.
Oh, wait.
Yep, the 181 shows up in the layout diagram on his site. I'm a little surprised, actually -- if you compromise enough to use GALs (programmable logic), it's kind of pointless to brag about being "TTL-based". If I build something out of a fistful of PICs, and hook them together with TTL-level signals, can I claim the same thing?
I built a "video card" for a TRS-80 as a hobby project about 25 years ago -- 50 or so chips, 8 or 10 solderless breadboards, and a baking sheet for support/ground-plane. 30 rows, 100 columns, 8x16 pixels per character, memory-mapped, and the only thing that wasn't SS/MS-TTL was the RAM for the display buffer and the character lookup table. I guess I spent six months or so building it up piece-by-piece -- the bus interface, then the clock and divider chain, then the character RAM, then the display RAM, then the driver. I'm still kind of amazed that I pulled it off. I actually used the whole thing as a terminal for a year or two, because 100x30 was so much more pleasant than 64x16. And once I wrote a VT52 emulator and a serial driver that could keep up with a 1200-baud modem, I could actually do visual editing from my dorm room -- the height of luxury, I'm telling you.
...not subscription or service fees. When AT&T broke up, they generously offered to let me buy the phone I'd been using for something like $20, rather than turning it in. I think I actually took them up on it, and still have the thing in a closet somewhere, complete with rotary dial and acoustic-coupler-compatible handset.
Pick a small set of standards that will work "well enough" and let them become the Legacy Standard. I'm so sick of going to garage sales and seeing good equipment, such as printers and scanners, that won't connect to any computer that I own. I have a drawer full of PS/2 keyboards.
Okay. Would the "good enough" legacy graphics standard be VGA? Oops, you'll have to toss all your EGA, CGA, Hercules and NTSC/PAL monitors. For serial connectivity, you could provide a DB-9, and carry around a toolbox full of gender-swappers, null modems and 9-pin/25-pin/mini-DIN/RJ45 connectors like your father did. For parallel, there's a "standard" of sorts that's still commonly seen -- but do you remember how to connect it to a Centronics 737? Oh, and don't forget the DB-15 for Ethernet transceivers -- I paid good money for all this thicknet, and there's no way I'm tossing it just because this newfangled twisted-pair stuff has 100 times the capacity.
Maybe instead of an optical drive, your laptop can have a pop-out shelf bearing an array of different connectors. You could even put some DIP sockets on the bottom so your old 16K RAM chips don't have to go to waste.
Besides, we all know that OTPs will eventually be regulated as munitions.