What do we really expect when people are fed a steady diet of superstition on TV? What are some of the most popular youth TV shows - Buffy, Charmed, Supernatural, etc.
Have you ever actually watched Buffy? Yeah, there are zombies and demons and reavers^W^W, but the people fighting them use science. You experiment, test, see what works. Just because it takes place in a Jossian universe doesn't make it any less logical.
Course, your main point still holds. More pseudosicence claptrap on TV every week, the worst being credulous woo-woo shows on places like Discovery Channel what ought to know better. Just let's keep that tar brush where it belongs.
3 millimeters per second squared, and after a week you're moving at 1.8 kilometers per second. After a month, 7.2 kilometers per second. After 2 months, you've already exceeded Earth's escape velocity from the surface, let alone from orbit. Solar escape velocity at 1 AU is about 48 kilometers per second, so it would take you half a year to get fast enough to escape the solar system altogether. Actually, less than that, because as you're accelerate you're moving outward and so the solar escape velocity from your present position is continuously decreasing, but I'm in no mood for calculus right now.
Except you're losing thrust faster than the escape velocity decreases. Escape velocity goes as 1/sqrt(r), whereas the light intensity (hence thrust) goes as 1/r^2. Solar sails probably aren't the best way to go interstellar. But then, neither is anything else we can imagine at the moment. sigh
And now, safely buried in the comments because I have limited bandwidth...
Photos of the Uchinoura Space Center, from back when they called it Kagoshima Space Center. (Kagoshima is the prefecture, Uchinoura is the town. Nobody in Japan has heard of Uchinoura, so they called it Kagoshima Space Center until with the increased level of joint projects with a certain American space agency they decided 'KSC' was too easy to confuse with Kennedy Space Center.)
For example, why didn't they consider IBM micro-drives?
Vacuum and radiation. The drives may be semi-hermetically sealed, but you need a whole nother level of reliability for space missions. If the drive area leaked to vacuum they would head-crash. But more importantly, it's highly unlikely they could survive the radiation environment.
Radiation hardening is still a problem, but that could be better solved by shielding the entire core computer instead of bothering with individual components.
Nope. Basically, you can't shield against Single-Event Upsets. The solar protons are too energetic; you need a prohibitively thick shield (inches, or feet, of metal). A flyable amount of shielding will reduce the total dose, which helps with radiation-induced aging, but won't stop those random bit-flips. Your only hope for them is to build the circuitry specifically to handle them. Which generally means some combination of bigger, slower, and more power-hungry. Since you can't afford more power, you get bigger and slower. Micro-drives were not designed with that tradeoff in mind.
About 10 pounds of plutonium dioxide should provide more power than the craft will ever need, for longer than the engines will last.
Plus all the associated radiators and electronics necessary to run an RTG. But admittedly the biggest obstacle to them is political, not technical. Please go convince the noisy bit of the public that RTG != Nuclear Bomb. Thanks.
It's a nice idea, but does anyone remember how much it cost last time we did it? I'd be in favor of it, but I can't pay for it myself. NASA's budget during the Apollo program peaked at over 4% of the national GDP. Are we willing to commit that same kind of money now?
Sure, some parts of the program would be cheaper, but containing and steering 3000-degree gases is still just as hard as it was back then. We have no hardware that even comes close to being powerful enough to reach the moon, so everything has to be designed, built, and tested from scratch.
Where exactly are we going to come up with a few hundred billion bucks to pay for this? Apollo cost on the order of $70B, which inflates to over $350B now. Reduce that some for better CAD and cheaper control systems, and increase it for better reliability and doing something more than just sending 7 missions of less than a week duration. Assume we can do it in 10 years (compared to 8 years for Apollo), and we need $35B per year. Unevenly spread, of course, so the peak would be close to $100B for a couple years.
Maybe we could raise that with a bake sale or something.
The CNN photo caption is wrong.
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Nobel Prizes Awarded
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· Score: 3, Informative
The CNN photo has Wieman and Cornell reversed. Eric is the one on the left. Not that anyone cares, but, y'know... I knew Eric Cornell, I worked with Eric Cornell, and Carl is no Eric Cornell.
My biggest problem with modern science (physics and astrophysics in particular) is this truly inane method of making "conjectural" observations
No, your biggest problem is reading about modern science on Slashdot. C'mon, people! Jeez, I understand when Terri Gross screws up her science interviews, but we ought to be able to do better. These commments (even the highly rated ones) are the worst description of cosmology I've seen in a long time. Bleah.
Okay, so let's start with this one.
Doesn't it make a LOT more sense to think that dark matter is just the stuff floating around that doesn't have any light bouncing off of it?
That's one possibility. In fact, that is exactly the MACHO (Massive Compact Halo Objects) hypothesis. Okay, quick primer on dark matter: First, there are two kinds of dark matter:
The stuff that must be in galaxies to explain their rotation curves
The stuff that would have to be there to make the universe flat
The first kind really has to be there, because we can measure its gravitational effect directly. But it ain't stars (we can see them), and it ain't dust or gas, because we can "see" that when we look through it. So that leaves large agglomerations of regular matter (MACHOS) or weakly interacting massive particles (WIMPS). WIMPS could be massive neutrinos, but the best estimate for neutrino mass probably isn't enough to account for it. And yes, the term MACHOS was chosen in response to the term WIMPS.
As for the second kind, the only "evidence" for that has until recently been theoretical. If the inflationary hypothesis is correct, the chances of the universe being as flat as we see it but not exactly flat are very very small. That of course is pretty limited evidence.
However, recent measurements of several separate parameters are starting to converge on a cohesive picture. The universe is flat, but has a term (referred to as "Dark Energy", "cosmological constant", or sometimes "quintessence") which accounts for about a third of the energy of the universe and will cause it to expand forever.
NASA has absolutely no incentive to reasearch alternative (and cheaper) launch methodologies because they are politically committed to the space shuttle (another massive boondoggle).
Half true. The shuttle is a huge political stone around NASA's neck, but there is still a strong desire in most of the agency to get launch costs down and reliability up.
The simple reality of the situation is that rocketry is hard. Here's a partial list of commercial enterprises trying to get in on it:
And of course the big boys like Boeing, Lock-Mart, and all the various non-Amurrican folks like Russia, China, Japan, and the EU.
Any of these enterprises would be, er, on top of the world if they could develop a low cost launch vehicle. It's much easier to grumble about how expensive access to space is than it is to actually do something about it. Whether NASA is going about it in a sensible way is a separate question, but it's not like all they're just sitting on their duffs waiting for the right incentive.
Re:That's been the trend in recent years
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Virtual Astronomy
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· Score: 1
If all scientific data were to be treated similarly - i.e. gather as you need - more resource could be put into the analysis as less is put into gathering. Data for its own sake is fine if you have unlimited resource. Most of us don't - not even Nasa during wartime.
But in astronomy at least, new missions (in the case of NASA that means spacecraft, but it applies to ground observatories as well) are mainly driven precisely by need. We've got all this great X-ray data from Chandra, and in many cases it leads to more questions that can't be answered by the data it can provide. Ergo, we build the next generation instrument.
Sure, we end up with lots of data that has other uses, and even some data that is never analyzed for lack of time. But don't think for a minute that we could learn anything like what we know by sitting back and just analyzing old data. You want to check the Iron K-line complex? Sorry, no existing data has the resolution.
Mind you, the project in question is A Good Idea. But I assure you that new missions are very competetive, and are approved only if the science to be gained is not achievable with current instruments.
Peter Meyers, a professor of physics at Princeton University who was not part of the research team, said the finding is the "sort of crack" that "has been sought for many, many years."
I am always wary of results obtained by any physicists who have spent years and years seeking any sort of crack.
The difficulty is in getting a sensor that can tell the controller what the air density is. The obvious way to do this would be with an accelerometer but these are expensive and don't really work well enough anyway (with current technology).
Well, no, actually. Accelerometers are not terribly expensive, and work just fine. Silicon Designs, for instance sells rad-hard ones. You also want to watch the temperature on various parts of the spacecraft. Temperature sensors are even cheaper than accelerometers.
Measuring what you need to measure is not hard, nor are the calculations. All we need is a better understanding of what controls the density at the top of the atmosphere. Once we have that, you can bet autonomous aerobraking will be as common as cherry pez.
Re:Aerobraking and probe intelligence...
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The Art of Aerobraking
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· Score: 5, Interesting
for christ sakes, I can get a Lego Mindstorms to run around my livingroom by itself; one would hope that we might be able to build a semi-autonomous space probe.
(3 minutes later, and atmosphere unexpectedly thickens) SP: oh no! Quick, recalculate! rocket, give me a 2 second burn then turn 43 degress for a 1 second burn!
Oop, doesn't work that way. Orbital mechanics is funny until you wrap your head around it. To change the perigee, you have to burn at the apogee. Once you're in the atmosphere, there's bugger all you can do about it until the next time around. (Well, unless you're carrying gobs of fuel, and if you can do that, the screw this aerobraking stuff.)
Of course, you can make the probe autonomously adjust the next pass based on the results of the current one. But I wouldn't want to even try until we have at least one more probe's worth of data on exactly how to model all this.
And in response to the AC who thinks that rad-hard processors aren't up to this, all I have to say is HAW! Go look up what processing power the guidance computer on Apollo 11 had, and marvel at how much you can do when you're not spending cycles drawing aqua-colored drop shadows. I could make a useful aerobraking auto-adjust system with an RTX-2010 and half a meg of RAM. (That's an 8 MHz Forth processor, folks.) If that's not enough for you, Lockheed-Martin is selling rad-hard 250 MHz PowerPC 750 boards for only two arms and a leg.
Has it been introduced to the Senate yet? And if so, what's the bill number? Useful information to have when bitching to your Senators.
Quite so. In this case, it has not been introduced; it's still draft legislation. Just refer to it as the SSSCA.
Also, the EFF is your friend. They have sample letters and legislators' addresses 'n' stuff.
Heh, the only thing unusual about this story is that a *hacker* changed the meaning of a story to suit an agenda. It's not as if the news wasn't biased already!
Bias schmias. How about plain ol' incompetence? The article at SecurityFocus says:
"You can imagine someone changing lists of people who were on the planes, or reported missing, or all kinds of things that could cause a lot of grief," says Denning. "Or posting stories attributing attacks to certain people."
Gee, just like CNN, ABC, MSNBC, Fox, and all the other sites and channels I was watching last week. A bomb at the state department. Fires on the national mall. 10 people arrested by SWAT teams on airplanes on Wednesday.
Not to mention the endless streams of TV anchors interviewing security experts with such penetrating questions as, "We'd really like this to have been done by Bin Laden, because then we'd have someone to blame. Could you please say his name a few times to lend some legitimacy to this hypothesis?".
Sure, I don't want someone tracking me, but keeping aggregate data wouldn't be bad. By doing this maybe they can speed up access to information instead of having me hunt around for what I want.
Yeah, just like the way all modern sites use the existing data (server logs, referrer info, yadda yadda) to improve the user experience.
The last thing these bozos (by which I mean every web designer except me!) need is more information to completely misinterpret. Sure, if people actually used the data sensibly it could be very helpful. What will actually happen instead is the marketing geniuses will generate a new set of first-level metrics and munge the sites to maximize that.
It will be just like current attempts to maximize the number of clicks on the "buy me" button. Only a very few will realize that maximum clickage does not translate to maximum long-term customer loyalty, sales, and those sorts of things that used to matter in the Old Economy.
My god, a posting from someone who actually knows what he's talking about! What is/. coming to? Nevertheless...
The Sony SACD skips the decimation and interpolation stage. It stores the noise-shaped bitstream directly on the disc. The beauty of this idea is in its simplicity: it performs much less transformations on the sigma-delta signal and therefore should offer inherently higher fidelity and wider bandwidth.
Just to be clear, the conversion to 44.1/16 doesn't add any noise or distortion, it just places an upper limit on the quality of the final product. Sony's scheme leaves that limit higher than that of CD's. Whether it's better than 96/24 isn't immediately obvious.
If sigma-delta converters were available 20 years ago when the CD was invented they would probably have chosen this method for its simplicity.
You got that right. And note also that delta-sigma converters were understood then, they just weren't feasible with the digital technology available. Also, please, it's "delta-sigma", not "sigma-delta" (see Note 1 in Oversampling for the curious the furious, and the damned). Which by the way is a nice review of oversampling, and I recommend it to nearly everyone else who has posted something in this discussion.
So is DVD-audio is actually better? Your point about tape bias signals gives the edge to SACD, though as you point out it doesn't apply to home listeners, only archivists. And DVD-audio is an existing standard. In which case I suppose it wins by default. As far as audible differences, there aren't going to be any, so that leaves only the lack of surround capability as the difference. Okay, so there you have it. 96 kHz is enough, 24 bits is way more than enough, but 2 channels is not enough. DVD-audio wins.
16 bits isn't enough. That's _really_ obvious at this point- no professional works in 16 bits except for the final CD output.
And the reason is... Because real-world signals have a lot more dynamic range than we can fit on the final output. Stick your ear into the bell of a trumpet or 2 inches under a snare drum and tell me how much hearing you have left after an hour. Yet you find microphones there all the time. When recording digitally, it's critical not to exceed the peak amplitude -- digital clipping is obvious and nasty. So you leave plenty of room at the top for extra-loud sounds, and adjust the volume when mixing it down. That means you want more than 16 bits to get 16 bits of resolution in the final product.
even if you mix with ideal noiseless coloration-less electronics
ARGH!! Digital mixing is addition. There's no noise or coloration to be added. If you want to add some, you have to add it on purpose.
44.1K isn't enough either.
Actually, this may be true. Some studies have shown pretty convincingly that a few people can detect the presence of tones close to 30 kHz. Whether such tones exist at detectable levels in actual music isn't clear. But the science does allow the possibility that a 60 or 70 kHz sample rate may be necessary. However...
High end amplifier designers go to great lengths to get their pass-bands up into the megahertz
Utter nonsense. Deliberately extending your passband that high would not only seriously compromise performance at audio frequencies, but it would make your amp incredibly sensitive to RF interference.
The neat thing about the bit rate is that it's effectively infinite bit rate
Not at all. What they describe is delta-sigma modulation, the same thing used in nearly all CD players today. From what I can tell, their scheme is simply a higher bit-rate delta-sigma system with the storage medium containing the 1-bit stream. There is absolutely nothing new about any of this.
There doesn't need to be _any_ brickwall filter on the output
Precisely. And this is in fact the very reason that delta-sigma modulation is used on commercial CD players (and most of the A/D converters used in the industry, as well). Again, the difference here (AFAICT) is that the 1-bit stream is what gets stored, rather than resampling to the 44.1/16 CD standard.
the potential slew rate of this technology is just astronomical
This has absolutely nothing to do with slew rate. Nothing at all. And slew rate has little to do with how loud something sounds. It is true that absurdly powerful amplifiers can sound better than smaller amps with otherwise equal specs. And you almost have it right; the reason is that the peaks require a lot more power than the average, and if you turn up the volume, the smaller amp can't produce the peak power needed for the transients. The result is clipping, which is audible.
However, again this has nothing to do with the storage medium. Remember, modern CDs are almost all recorded and played back using delta-sigma modulation. Sony's plan is to simply skip the current step where the bitstream is reorganized to 16 bits at 44.1 kHz. This allows them to choose a bit rate with a higher dynamic range and cutoff frequency. I leave the arguments about the need for those to other postings.
There are a lot of people in this world who can hear the difference and suggest that the CD format is severely limited in terms of it's frequency range.
Course, they're just fooling themselves. In any careful blind listening test, with decent quality components in working order, under realistic listening conditions, nobody can hear the difference between the source tape and a CD copy, and anybody can hear the difference between source tape and a vinyl copy.
You are free to state that you like the sound of LPs better, but it is undeniable that the reason is that vinyl is changing the sound. I prefer to hear what the producer intended. If he wants to add modulation noise, channel-to-channel phase noise, and high-frequency rolloff, that's his choice. I just don't want the storage medium to add any.
Note: it is possible to hear differences between CD players when listening to low-level digitally-generated test signals with the volume turned way up. But:
Those differences disappear when listening to actual recorded music.
The differences are in the implementation of the D/A section of the players; the signal recorded on the disc is the same.
But apart from those unmanned probes, they are doing nothing right now other than spinning their wheels and building big useless sound stages in space.
Let's see, from next year's appropriations, in millions...
Space Science Total $2,398.8 Life/Microgravity S&A Total $302.4 Earth Science Total $1,405.8 SPACE STATION $2,114.5 SPACE SHUTTLE $3,165.7
(<pre> would be a nice tag to allow here, Mr. Slash coder...)
So shuttle plus station is getting slightly more than science. I'd prefer more for science, but it's hardly nothing.
As others have pointed out here, you can trade bandwidth for latency, by such tricks as not trying to compress. In the Cheshire article, he mentions that the Apple Geoport semi-modem should have been able to reduce latency considerably, by knowing when a packet was complete (but didn't). The same argument applies to WinModems, if I understand them correctly. But I bet they don't do that either.
Anywyay, whether this thing actually works, it certainly is technically reasonable.
To the best of my understanding, this statement is false.
No, it's true.
They are not claiming that these conditions haven't existed since the big bang. (That would be absurd.) This will simply be the first time such conditions have been recreated in a lab.
Please, reread the bit about cosmic rays. Every day the earth is bombarded by millions (I'm way underestimating here) of cosmic ray particles so energetic that they laugh heartily at the feeble attempts of Brookhaven to match them.
When we do it in a lab, we can be there to watch. But as far as the earth is concerned, it is very old hat indeed.
About halfway through I was wondering where he would put Snow Crash, with its clearly marginalized Protagonist but relentless humor. I was glad to see it on the "uncategorizeable" list. For that matter, where would The Big U go? It's got all the cyberpunk ingredients except for the science fiction.
OTOH, usually I see connections where normal people don't. Does anybody else see the similarities between the Hyperion series and Dave Matthews Band? Or am I just odder than I thought?
But this/may/ be a case where lightweight processes failed.
Oh yes, things were so much better when they had all that additional money to spend on reviews and program management. You know, back when they created the Hubble Space Telescope and the Galileo antenna.
Okay, sorry. Clearly there should be a system in place to ensure the units from contractors are clearly specified and understood. Bet there already is, actually. But the point is that adding layers of reviews and management does not have any measureable effect on success rate.
The real advantage of better/faster/cheaper is that even though your failure rate is the same, you don't lose so much each time you lose a spacecraft. So you're not tempted to spend all that money on reviews and procedures that don't actually help.
On the other hand, I happen to know that there are in fact parts of certain space agencies that could use *more* formality and discipline. (cough)CVS!(cough).
I seem to remember reading an article a while back discussing the possibility that gravity warps time/space
Er, yes, that's known as General Relativity, and is pretty well understood. The test satellite you mention is Gravity Probe B, scheduled for launch next year.
This sort of thing has certainly been taken into account. Compared to predicting the force due to thermal radiation from the satellites, it's easy. And thermal radiation will always result in a sunward force, because you put the radiators on the dark side of the spacecraft (unless you want it to get really hot while it's still in the inner solar system.)
Slashdot Mirror
Have you ever actually watched Buffy? Yeah, there are zombies and demons and reavers^W^W, but the people fighting them use science. You experiment, test, see what works. Just because it takes place in a Jossian universe doesn't make it any less logical.
Course, your main point still holds. More pseudosicence claptrap on TV every week, the worst being credulous woo-woo shows on places like Discovery Channel what ought to know better. Just let's keep that tar brush where it belongs.
Except you're losing thrust faster than the escape velocity decreases. Escape velocity goes as 1/sqrt(r), whereas the light intensity (hence thrust) goes as 1/r^2. Solar sails probably aren't the best way to go interstellar. But then, neither is anything else we can imagine at the moment. sigh
And now, safely buried in the comments because I have limited bandwidth...
Photos of the Uchinoura Space Center, from back when they called it Kagoshima Space Center. (Kagoshima is the prefecture, Uchinoura is the town. Nobody in Japan has heard of Uchinoura, so they called it Kagoshima Space Center until with the increased level of joint projects with a certain American space agency they decided 'KSC' was too easy to confuse with Kennedy Space Center.)
Vacuum and radiation. The drives may be semi-hermetically sealed, but you need a whole nother level of reliability for space missions. If the drive area leaked to vacuum they would head-crash. But more importantly, it's highly unlikely they could survive the radiation environment.
Radiation hardening is still a problem, but that could be better solved by shielding the entire core computer instead of bothering with individual components.
Nope. Basically, you can't shield against Single-Event Upsets. The solar protons are too energetic; you need a prohibitively thick shield (inches, or feet, of metal). A flyable amount of shielding will reduce the total dose, which helps with radiation-induced aging, but won't stop those random bit-flips. Your only hope for them is to build the circuitry specifically to handle them. Which generally means some combination of bigger, slower, and more power-hungry. Since you can't afford more power, you get bigger and slower. Micro-drives were not designed with that tradeoff in mind.
About 10 pounds of plutonium dioxide should provide more power than the craft will ever need, for longer than the engines will last.
Plus all the associated radiators and electronics necessary to run an RTG. But admittedly the biggest obstacle to them is political, not technical. Please go convince the noisy bit of the public that RTG != Nuclear Bomb. Thanks.
Sure, some parts of the program would be cheaper, but containing and steering 3000-degree gases is still just as hard as it was back then. We have no hardware that even comes close to being powerful enough to reach the moon, so everything has to be designed, built, and tested from scratch.
Where exactly are we going to come up with a few hundred billion bucks to pay for this? Apollo cost on the order of $70B, which inflates to over $350B now. Reduce that some for better CAD and cheaper control systems, and increase it for better reliability and doing something more than just sending 7 missions of less than a week duration. Assume we can do it in 10 years (compared to 8 years for Apollo), and we need $35B per year. Unevenly spread, of course, so the peak would be close to $100B for a couple years.
Maybe we could raise that with a bake sale or something.
And singing, what's up with that?
Half true. The shuttle is a huge political stone around NASA's neck, but there is still a strong desire in most of the agency to get launch costs down and reliability up.
The simple reality of the situation is that rocketry is hard. Here's a partial list of commercial enterprises trying to get in on it:
And of course the big boys like Boeing, Lock-Mart, and all the various non-Amurrican folks like Russia, China, Japan, and the EU.
Any of these enterprises would be, er, on top of the world if they could develop a low cost launch vehicle. It's much easier to grumble about how expensive access to space is than it is to actually do something about it. Whether NASA is going about it in a sensible way is a separate question, but it's not like all they're just sitting on their duffs waiting for the right incentive.
But in astronomy at least, new missions (in the case of NASA that means spacecraft, but it applies to ground observatories as well) are mainly driven precisely by need. We've got all this great X-ray data from Chandra, and in many cases it leads to more questions that can't be answered by the data it can provide. Ergo, we build the next generation instrument.
Sure, we end up with lots of data that has other uses, and even some data that is never analyzed for lack of time. But don't think for a minute that we could learn anything like what we know by sitting back and just analyzing old data. You want to check the Iron K-line complex? Sorry, no existing data has the resolution.
Mind you, the project in question is A Good Idea. But I assure you that new missions are very competetive, and are approved only if the science to be gained is not achievable with current instruments.
Well okay, but see I wacky-parsed the headline as
Linux 2.4.15 is out; Ringo's in
So naturally I clicked on it.
I am always wary of results obtained by any physicists who have spent years and years seeking any sort of crack.
(Sorry about that)
Well, no, actually. Accelerometers are not terribly expensive, and work just fine. Silicon Designs, for instance sells rad-hard ones. You also want to watch the temperature on various parts of the spacecraft. Temperature sensors are even cheaper than accelerometers.
Measuring what you need to measure is not hard, nor are the calculations. All we need is a better understanding of what controls the density at the top of the atmosphere. Once we have that, you can bet autonomous aerobraking will be as common as cherry pez.
You mean like Deep Space 1? Or Clementine? Yep, it's being done.
(3 minutes later, and atmosphere unexpectedly thickens) SP: oh no! Quick, recalculate! rocket, give me a 2 second burn then turn 43 degress for a 1 second burn!
Oop, doesn't work that way. Orbital mechanics is funny until you wrap your head around it. To change the perigee, you have to burn at the apogee. Once you're in the atmosphere, there's bugger all you can do about it until the next time around. (Well, unless you're carrying gobs of fuel, and if you can do that, the screw this aerobraking stuff.)
Of course, you can make the probe autonomously adjust the next pass based on the results of the current one. But I wouldn't want to even try until we have at least one more probe's worth of data on exactly how to model all this.
And in response to the AC who thinks that rad-hard processors aren't up to this, all I have to say is HAW! Go look up what processing power the guidance computer on Apollo 11 had, and marvel at how much you can do when you're not spending cycles drawing aqua-colored drop shadows. I could make a useful aerobraking auto-adjust system with an RTX-2010 and half a meg of RAM. (That's an 8 MHz Forth processor, folks.) If that's not enough for you, Lockheed-Martin is selling rad-hard 250 MHz PowerPC 750 boards for only two arms and a leg.
Quite so. In this case, it has not been introduced; it's still draft legislation. Just refer to it as the SSSCA.
Also, the EFF is your friend. They have sample letters and legislators' addresses 'n' stuff.
Bias schmias. How about plain ol' incompetence? The article at SecurityFocus says:
Gee, just like CNN, ABC, MSNBC, Fox, and all the other sites and channels I was watching last week. A bomb at the state department. Fires on the national mall. 10 people arrested by SWAT teams on airplanes on Wednesday.
Not to mention the endless streams of TV anchors interviewing security experts with such penetrating questions as, "We'd really like this to have been done by Bin Laden, because then we'd have someone to blame. Could you please say his name a few times to lend some legitimacy to this hypothesis?".
Trusted, indeed.
Yeah, just like the way all modern sites use the existing data (server logs, referrer info, yadda yadda) to improve the user experience.
The last thing these bozos (by which I mean every web designer except me!) need is more information to completely misinterpret. Sure, if people actually used the data sensibly it could be very helpful. What will actually happen instead is the marketing geniuses will generate a new set of first-level metrics and munge the sites to maximize that.
It will be just like current attempts to maximize the number of clicks on the "buy me" button. Only a very few will realize that maximum clickage does not translate to maximum long-term customer loyalty, sales, and those sorts of things that used to matter in the Old Economy.
Now if you'll excuse me I need a Jakob fix.
The Sony SACD skips the decimation and interpolation stage. It stores the noise-shaped bitstream directly on the disc. The beauty of this idea is in its simplicity: it performs much less transformations on the sigma-delta signal and therefore should offer inherently higher fidelity and wider bandwidth.
Just to be clear, the conversion to 44.1/16 doesn't add any noise or distortion, it just places an upper limit on the quality of the final product. Sony's scheme leaves that limit higher than that of CD's. Whether it's better than 96/24 isn't immediately obvious.
If sigma-delta converters were available 20 years ago when the CD was invented they would probably have chosen this method for its simplicity.
You got that right. And note also that delta-sigma converters were understood then, they just weren't feasible with the digital technology available. Also, please, it's "delta-sigma", not "sigma-delta" (see Note 1 in Oversampling for the curious the furious, and the damned). Which by the way is a nice review of oversampling, and I recommend it to nearly everyone else who has posted something in this discussion.
So is DVD-audio is actually better? Your point about tape bias signals gives the edge to SACD, though as you point out it doesn't apply to home listeners, only archivists. And DVD-audio is an existing standard. In which case I suppose it wins by default. As far as audible differences, there aren't going to be any, so that leaves only the lack of surround capability as the difference. Okay, so there you have it. 96 kHz is enough, 24 bits is way more than enough, but 2 channels is not enough. DVD-audio wins.
16 bits isn't enough. That's _really_ obvious at this point- no professional works in 16 bits except for the final CD output.
And the reason is... Because real-world signals have a lot more dynamic range than we can fit on the final output. Stick your ear into the bell of a trumpet or 2 inches under a snare drum and tell me how much hearing you have left after an hour. Yet you find microphones there all the time. When recording digitally, it's critical not to exceed the peak amplitude -- digital clipping is obvious and nasty. So you leave plenty of room at the top for extra-loud sounds, and adjust the volume when mixing it down. That means you want more than 16 bits to get 16 bits of resolution in the final product.
even if you mix with ideal noiseless coloration-less electronics
ARGH!! Digital mixing is addition. There's no noise or coloration to be added. If you want to add some, you have to add it on purpose.
44.1K isn't enough either.
Actually, this may be true. Some studies have shown pretty convincingly that a few people can detect the presence of tones close to 30 kHz. Whether such tones exist at detectable levels in actual music isn't clear. But the science does allow the possibility that a 60 or 70 kHz sample rate may be necessary. However...
High end amplifier designers go to great lengths to get their pass-bands up into the megahertz
Utter nonsense. Deliberately extending your passband that high would not only seriously compromise performance at audio frequencies, but it would make your amp incredibly sensitive to RF interference.
The neat thing about the bit rate is that it's effectively infinite bit rate
Not at all. What they describe is delta-sigma modulation, the same thing used in nearly all CD players today. From what I can tell, their scheme is simply a higher bit-rate delta-sigma system with the storage medium containing the 1-bit stream. There is absolutely nothing new about any of this.
There doesn't need to be _any_ brickwall filter on the output
Precisely. And this is in fact the very reason that delta-sigma modulation is used on commercial CD players (and most of the A/D converters used in the industry, as well). Again, the difference here (AFAICT) is that the 1-bit stream is what gets stored, rather than resampling to the 44.1/16 CD standard.
the potential slew rate of this technology is just astronomical
This has absolutely nothing to do with slew rate. Nothing at all. And slew rate has little to do with how loud something sounds. It is true that absurdly powerful amplifiers can sound better than smaller amps with otherwise equal specs. And you almost have it right; the reason is that the peaks require a lot more power than the average, and if you turn up the volume, the smaller amp can't produce the peak power needed for the transients. The result is clipping, which is audible.
However, again this has nothing to do with the storage medium. Remember, modern CDs are almost all recorded and played back using delta-sigma modulation. Sony's plan is to simply skip the current step where the bitstream is reorganized to 16 bits at 44.1 kHz. This allows them to choose a bit rate with a higher dynamic range and cutoff frequency. I leave the arguments about the need for those to other postings.
Course, they're just fooling themselves. In any careful blind listening test, with decent quality components in working order, under realistic listening conditions, nobody can hear the difference between the source tape and a CD copy, and anybody can hear the difference between source tape and a vinyl copy.
You are free to state that you like the sound of LPs better, but it is undeniable that the reason is that vinyl is changing the sound. I prefer to hear what the producer intended. If he wants to add modulation noise, channel-to-channel phase noise, and high-frequency rolloff, that's his choice. I just don't want the storage medium to add any.
Note: it is possible to hear differences between CD players when listening to low-level digitally-generated test signals with the volume turned way up. But:
Let's see, from next year's appropriations, in millions...
Space Science Total $2,398.8
Life/Microgravity S&A Total $302.4
Earth Science Total $1,405.8
SPACE STATION $2,114.5
SPACE SHUTTLE $3,165.7
(<pre> would be a nice tag to allow here, Mr. Slash coder...)
So shuttle plus station is getting slightly more than science. I'd prefer more for science, but it's hardly nothing.
Source: American Institute o' Physics
Part One Part Two
As others have pointed out here, you can trade bandwidth for latency, by such tricks as not trying to compress. In the Cheshire article, he mentions that the Apple Geoport semi-modem should have been able to reduce latency considerably, by knowing when a packet was complete (but didn't). The same argument applies to WinModems, if I understand them correctly. But I bet they don't do that either.
Anywyay, whether this thing actually works, it certainly is technically reasonable.
No, it's true.
They are not claiming that these conditions haven't existed since the big bang. (That would be absurd.) This will simply be the first time such conditions have been recreated in a lab.
Please, reread the bit about cosmic rays. Every day the earth is bombarded by millions (I'm way underestimating here) of cosmic ray particles so energetic that they laugh heartily at the feeble attempts of Brookhaven to match them.
When we do it in a lab, we can be there to watch. But as far as the earth is concerned, it is very old hat indeed.
Nah, really it's all rock 'n' roll.
About halfway through I was wondering where he would put Snow Crash, with its clearly marginalized Protagonist but relentless humor. I was glad to see it on the "uncategorizeable" list. For that matter, where would The Big U go? It's got all the cyberpunk ingredients except for the science fiction.
OTOH, usually I see connections where normal people don't. Does anybody else see the similarities between the Hyperion series and Dave Matthews Band? Or am I just odder than I thought?
Oh yes, things were so much better when they had all that additional money to spend on reviews and program management. You know, back when they created the Hubble Space Telescope and the Galileo antenna.
Okay, sorry. Clearly there should be a system in place to ensure the units from contractors are clearly specified and understood. Bet there already is, actually. But the point is that adding layers of reviews and management does not have any measureable effect on success rate.
The real advantage of better/faster/cheaper is that even though your failure rate is the same, you don't lose so much each time you lose a spacecraft. So you're not tempted to spend all that money on reviews and procedures that don't actually help.
On the other hand, I happen to know that there are in fact parts of certain space agencies that could use *more* formality and discipline. (cough)CVS!(cough).
Er, yes, that's known as General Relativity, and is pretty well understood. The test satellite you mention is Gravity Probe B, scheduled for launch next year.
This sort of thing has certainly been taken into account. Compared to predicting the force due to thermal radiation from the satellites, it's easy. And thermal radiation will always result in a sunward force, because you put the radiators on the dark side of the spacecraft (unless you want it to get really hot while it's still in the inner solar system.)
Well, they may not have been in this work, but X-rays certainly can be focused. See, for example, the Chandra image of Cas A.
It doesn't get much more focused than that!