The paper said that one of the targets that apparently was affected was 150 m from the "generator".. Would be pretty nifty vibrations that caused a target 150m away in another building to move 14cm sideways...
A single, sharp impulse might do it, and IMO that's more likely than a gravity beam.
However, looking over the links other posters have supplied, I suspect fraud is the most likely explanation.
While I question the researchers' conclusions, if the effects they claim to observe occurred, it's probably worth trying to duplicate the experiment. If nothing else, it would teach us about how to properly shield and isolate discharge rigs to prevent spurious effects like they saw, and at best there might even be something new going on here.
My personal suspicion is that either their Faraday cage was flawed, or they neglected to put the capacitor bank in the cage (the whole discharge circuit loop will act as an induction coil), or that they neglected to put both the discharge rig (with bank) and the test jars on vibration isolation tables (send a current pulse through a loop of cabling, and the cabling will *vibrate*).
That, or the observations are false or embellished.
Either way, the experiment is easy to duplicate (they were very good about describing their apparatus and methods), and there are quite a few points where more thorough control would help pin down the nature of whatever's happening. It's cheap enough, so I can see a university's physics department doing it for a lark. This is exactly how science should work.
Silver Fluoride (the substance the article is talking about) is often used by dentists for fluoride treatments on weakened teeth.
Actually, no. The article talks about a very different type of silver compound.
Silver fluoride has silver as the cation and fluorine as the anion.
A fluoroargentate has something else as the cation (sodium and potassium were mentioned in the article), and AgFx as the anion (AgF3 and AgF4 were mentioned in the article). This is same style of compound as phosphates, nitrates, and so forth, but with an exotic, less stable anion.
Forgot another ongoing cost - making new revisions of a chip to fix bugs or reduce power consumption or better tune the chip to the fab process used. Chips need just as much ongoing maintenance and tinkering as software does, even if the first version runs adequately.
Again, just like software debugging, this sucks up a vast amount of time and effort and resources for the manufacturer.
One reason a company makes the premium product higher is because they need to recover R&D on that product, however I don't see why this is in the chip market. I honestly feel that Intel and AMD "milk" the market for these gurus/morons knowing they will always buy the greatest. So they release a 1.0ghz and these people get that, then they release 1.1ghz and they get this one, etc etc. Although AMD has the 1.0 and 1.1 developed at the same time, they strategically release the products to the general pulic to maximize their profits.
It's quite possible that they _need_ to do this continuously to recover the R&D costs and other overhead costs.
Chip cad/simulation tools cost $0.5M-$1M per _seat_. Prototyping runs cost $300k+ each. The test gear and special-purpose simulation rigs aren't cheap either. A fabrication plant costs over $1B to build, which must be amortised over all chips manufactured there until the next major fab overhaul (typically only 2-3 years away).
Chip design and manufacture is _expensive_. I seriously doubt that they're gouging as badly as you seem to feel they are.
(In case you're wondering how smaller low-end x86-makers survive - they outsource their fabrication, which saves on amortized fab costs and capital at the cost of not having a fab process optimized for their chips (taking a performance hit). If they're wise, they'd also design their chips to either be more robust, or more easily tested, or both, to cut down on simulation/testing costs at the expense of performance.)
I also have to wonder about the validity of these emails and message board posts that show up on shows like CNN's 'talkback live' or 'news site'. Not trying to sound like a conspiracy nut, but we know the media massages news to their liking, how are we to know that they dont try to portray joe six-pack as being in favor or against said subject?
This happens in dead-tree publications on a routine basis, so I'd be surprised *not* to see it in online publications that let the admins - as opposed to the users - choose which replies have prominence.
[User-moderated boards have their own problems, as we all know.]
In the publications around here (Toronto, Canada), papers will typically print "letters to the editor" that either a) continue an existing argument amongst readers, or b) provoke a flood of replies. Note that sanity and accuracy are not listed as requirements; they're an incidental side effect. Sometimes.
The purpose of the letters section is the same as any other section of the newspaper (other than ads) - to get people reading and keep people reading. Not to be accurate for accuracy's own sake.
Astroturfing and other message forgery is still illegal, but selective filtering is standard practice.
This is just a stock SH4 machine with custom peripherals. *BSD has been ported to many such devices, and so has Linux (Dreamcast being the first that comes to mind, but there are SH4-based PDAs which are probably supported too).
If demand exists, and if the product rolls out in quantity at a decent price point, distributions for pick-your-favourite-*NIX will be out in short order.
Bear in mind that all we've seen as a "license agreement... to develop" a device like this. They look serious about it, but for now, it's still vapour.
The article reads like a summary of all of the non-lethal crowd control ideas that have been endlessly bandied around during the last couple of decades.
Crowd control techniques that are conspicuously absent from real use.
The problem is that things like lasers and sonic weapons and electrified water guns are more expensive and/or more difficult to keep non-lethal than good old-fashioned tear gas and pepper spray and firehoses.
Lasers blind people. Sonic weapons turn their bowels to jelly, harm internal organs, or both. Electrified water guns have nasty effects on anyone with a pacemaker or just a weak heart. And so forth.
With increased cost and increased number of lawsuits, I don't see why any riot-control force would use them.
Ok, so what's the payload to orbit for this six foot rocket?
Payload for a six-foot rocket would be about 5 kg (10 lbs) or so, assuming that 1% of the rocket's mass is cargo. This is a conservative estimate.
You can fit many kinds of research satellite into this weight restriction. Sensor, camera, and Earth-observing telescope packages don't have to be that large or heavy, and as long as you have a large ground station to handle communications, the satellite's power requirements will be low.
It would be tempting to try to launch something like a low-earth-orbit cell phone repeater, but you'd need a much heavier satellite for that (a communications satellite uses a lot of power).
Right now small satellites like I've described are already used; they're just launched in the leftover cargo space on larger rockets, or in large groups from larger rockets that a coalition of users buys space on.
Why has nobody built a small payload launch facility at altitude somewhere that there is a mountain range on a tropical east coast? Because while 20 miles is good, 2 miles is still above a lot of the atmosphere, no? Just political reasons?
Mainly because the payoff doesn't justify the cost. At 2 miles, you'd still have about 70% of the atmosphere above you, so your rocket would still be quite large. And if you can afford to build a rocket base on top of a mountain and transport rockets there, you can afford to build big rockets in the first place, and don't have a problem with atmosphere thickness:).
Good thought, though.
it would still be nice to see people aiming for orbit.
Agreed.
A rocket that could launch a human's worth of cargo would probably be big enough that you could launch it from the ground (and be expensive as all heck, alas).
So this group has figured that in getting to 120km of altitude, the atmosphere is a big part, so a baloon can make the difference. Great, but what use is it in getting us closer to private space ventures, which is what the X prize was supposed to be about?
It's useful because the same technique lets you build much smaller orbital spacecraft.
To have enough delta-v to reach orbit with chemical fuels, your rocket has to be mostly fuel (between 90% and 95%, depending on the specific impulse of the fuel).
The strength-to-weight ratio of your rocket's frame gets better as your rocket gets smaller. This makes it much easier to build, say, a six-foot rocket that's 95% fuel than a 60-foot rocket that's 95% fuel.
Your rocket will lose energy as it plows through the atmosphere. As you make the rocket bigger, this becomes less of a problem. The balance point is where the cross-sectional mass of your rocket (mass per unit cross-sectional area) becomes greater than the cross-sectional mass of the column of air that it's plowing through.
At sea level, that's about 10 tons per square yard. Your rocket has to be about 30 feet high to reach the balance point, and would ideally be much larger. This will be a big, expensive rocket, and making it 95% fuel will be difficult.
Go up 20 miles or so, and you're above 90% of the atmosphere. The tradeoff point happens when your rocket is 3 feet long. Remember how I said building a 6-foot rocket that's 95% fuel is easier than building a 60-foot one? You could build something like this in a garage. All you need to have an orbit-capable mini-rocket is a way to bring the launch platform 20 miles into the air.
A mini-rocket would still be very commercially viable. Do a web search for "nanosat" and "picosat" to find projects that could be launched on a rocket this size.
A balloon is a great way to do this. Various types of powered aircraft might be able to make the trip too.
*That* is the benefit of this type of project - researching a practical launch platform that could be used for small, orbit-capable rockets.
No, my little minions of evil don't have to have any intelligence at all, they merely have to be able to make random changes in themselves and be able to evaluate those changes in regards to a given set of hostile conditions.
...And this feeds back to the whole Gray Goo question: _can_ nanobots be built that could turn most matter into copies of themselves?
I personally think that this is very unlikely to be a problem. Special-purpose nanobots - e.g. ones optimized for construction given external power and matter supplies - can be very efficient. General-purpose nanobots would be less so. If you try to adapt a nanobot to the task of replicating as much as possible using ambient sources of matter and energy, you'll get something with performance characteristics much like existing replicators with similar design goals - bacteria.
I have yet to see a convincing argument that general-purpose nanomachines could be more efficient than bacteria at spreading and transforming the world about them. Both have abundant supplies of raw material, but both are limited by energy and by competition with other life forms.
But, we are talking about nanobots here, they would most likely have the ability to replicate themselves, and why replicate an inherit design flaw, like a dependance on something?
Easy - because they're too dumb to modify their own designs.
Designing a system that can design or improve the design of systems as complicated as itself is another task that's comparable to solving the Strong AI Problem.
You could argue that mutations might let them evolve, eventually, but nanomachines would be much less suceptible to mutation than biological replicators (by design - you don't want a cosmic ray to cause future generations of nanobots build houses without foundations, for instance).
You'd probably give nanobots the hard-coded pattern for replicating themselves, and the ability to download large structure designs from your database when building things. That way you don't have to give your nanobots the designs for every structure you could conceivably want to build, and they wouldn't have to do any design work at *all*.
Now, someone could deliberately build nanobots that would try to replicate ad infinitum, but that's for another thread.
How much energy is needed to power this thing? And isn't there a lot of energy released when the positrons finally hit some electrons? Or does that energy get reabsorbed somehow?
The positrons produce gamma rays when they are finally annihilated in the target, which will ultimately end up as heat in your radiation shielding.
The positron source is a radioactive isotope that naturally emits positrons. This means that the total amount of energy involved will be quite low (very few positrons). It's a testament to the engineering skill of the people who built the microscope that they can get the results they do, with such a small number of positrons.
The radioactive isotope is probably produced by sticking a container of appropriate source material into a fission reactor's core for a few hours/days/weeks. That's how most medical isotopes are produced.
Because making the nanomachines understand the Three Laws requires a solution to the Strong AI Problem. This will not be a cakewalk, and will be overkill for the vast majority of applications of nanomachines.
Building in an "off" switch or a dependence on a specific environmental factor would work at least as well and would be far easier.
Hahahah. It's not total bullshit, but how many users do you honestly think know how to compile something (as easy as it may be)?
That's why the web sites of large applications offer binaries compiled for multiple platforms and linux versions.
All you'd need to do would be to convince them to make builds for pick-your-favourite-platform.
Alternatively, you could find one dedicated person to build all of the apps you want to use for the target machine, and host their own site with the packages for the masses to download.
Installation will still likely be a pain, but the user won't have to futz around compiling things.
But isn't the beauty of Open Source the fact that you can just acquire and compile any needed programs for your favorite platform? Or is that just propaganda bullshit?
If the code was written cleanly, you can do it with a simple recompile.
If the code makes assumptions about, say, the endianness of the machine or the number of bits in a word, then it will probably break.
Whether a given piece of code is cross-platform-safe or not is luck of the draw (you're hoping that the coder had enough motivation to put in the extra work to make it portable).
If the internal fields remain 'for 15 years' then the power consumption of the chip should hopefully be lower, since the cache shouldn't need power refresh.
Caches already don't need (much) power to refresh. They're made of CMOS SRAM, which means that they only dissipate a lot of power when their state changes (ideally they'd dissipate none when the state isn't changing, but there's leakage current across gates and across junctions to the substrate).
Caches are power-hungry because any access has to a) do a tag lookup and b) propagate itself across the entire cache. There are tricks you can use to reduce the power cost of this, but this will still dominate by far over static power requirements.
Heat generation within both caches and the chip core is mainly caused by changing states and shuffling information around, not by maintaining an existing state. I've been studying this for a few years now:).
It seems that a lot of people really like this book, and I'm definately going to skim the on-lin version to see if I want to buy it, but I wonder how hard is it for someone with intermediatte experience coding to learn to make drivers? Anyone able to share their ordeals with it?
The first edition of the book was quite good for this; it had many examples of simple drivers scattered within to illustrate what it was talking about, which was very helpful.
My best advice would be to a) write a couple of toy drivers to get a feel for things, and b) take apart an existing driver and see how it works. I wrote an I/O space interface driver that I used to play with parallel ports, and a PCI-scanning driver; both purposes are already served by other parts of Linux, but it was still fun. I also had the dubious joy of wading throught the LML-33 video capture card's driver. I learned a lot by doing both, though, and the book was an invaluable reference.
Laser beams do spread out.
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Optical SETI
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· Score: 2
Yes, light does obey the Inverse Square Law. A laser does not because the light has been manipulated to make the photons travel parallel to each other, thus it does not "spread its influence equally in all directions".
Your laser beam diffracts as it passes through any finite-sized aperture (the laser mirrors count as apertures for this). This causes the resulting beam to diverge (think back to the single-slit diffraction experiment in high school physics class).
A diverging beam can be thought of as a cone. The area of a cone's cross-section goes up as the square of the distance from the origin, so the intensity of the laser light will indeed go down as the inverse square. In a real laser beam, the distribution vs. angle is gaussian instead of uniform, but the same principle applies.
Using a wider beam would result in a narrower cone, but your aperture would have to be at least 10 km wide to have a spot size as small as a planet at a distance of 10 light-years. So, any practical laser would spread out like a cone that covers a lot more area than the target.
Re:How do ET aim at a moving target?
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Optical SETI
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· Score: 3
What do you think? Are we (Terrans) currently able to target a laser beam on a planet 1, 10, 100 light years away?
Short answer: Yes, but it would be expensive.
Long answer:
Stars and planets have (relatively) easily-plotted courses. Spend a few months with a big telescope, and you can do any fine-tuning you need to in your model of the planet or parent star's trajectory. Put a big beam splitter in front of the telescope, fire a huge, very expensive laser at the beam splitter, and you can send the laser beam to the target system while using the telescope to make sure it's going in the right direction.
Target _system_?
Well, the problem is that your laser's aperture is small enough that diffraction prevents you from focusing it on something as small as a planet over interstellar distances. So you'll probably end up bathing most of the inner system of the destination star in weak laser light. Your laser has to be quite bright to be picked up (even if you pulse it), which means very, very expensive.
Alternatively, you can build an array of many lasers in space, and pull evil tricks to keep them all in phase with each other. This gives you a very large synthetic aperture, which would let you target the laser at a single planet. Of course, you'd need a synthetic aperture optical telescope of comparable size to _track_ the planet, but if you can build the laser, the telescope is within reach also.
This is "stupidly expensive", as opposed to merely "insanely expensive", but it could be done. We'd have to do something similar if we wanted to easily launch sailcraft over interstellar distances.
Does that mean that someone has been actually sent to space using this vehicle?
No. As described in the article, this test was a takeoff followed by a few hundred metres of flight near the ground followed by landing, to see if the craft was airworthy.
*Also* as described in the article, this isn't a craft that can achieve stable orbit. It's intended for sub-orbital flight to orbital altitude, which is a *lot* easier to do. The company feels that tourists will still pay for it. This project also lets them fine-tune their reusable rocket technology.
If page typesetting doesn't have to be pixel-perfect, clean HTML should be fine. As other posters have pointed out, the look of the document will vary from browser to browser, but for most of the documents I write, that's perfectly acceptable.
If page typesetting _is_ important, how about zipped postscript files? Postscript files are huge, but compressing them solves that problem adequately. This is transparent enough to the user to be acceptable (click on it, and WinZip pops up a nice window with the uncompressed file listed in it).
If you're using the postscript option, it's probably wise to have a link to the Windows version of GhostView on the same page that provides the documents, to minimize viewing hassles. Maybe WinZip too, though most people who download things will have that installed already.
Links to Linux and Mac binaries would be useful too, but Windows support should be the first design priority if this is a commercial site (by sheer force of demographics).
Please, do not use all the water in the oceans just for fueling the fusion in those power plants... We (mankind) need it as long as we want to actually LIVE on this planet...
You'd only need to take the deuterium for the first million years. Removing 1/7000 of the oceans' water would not cause substantial problems.
anyone with a tenth of an IQ point knows that fusion is clean and safe, unlike fission.
Fusion is certainly safer than fission from a high-level waste point of view, but how exactly do you propose to prevent the reactor vessel from becoming radioactive? Even "relatively few" neutrons is enough to cause major headaches for disposal of replaced parts for a multi-gigawatt reactor.
Claiming that it's perfectly clean will only make backlash worse when the public finally clues in. Remember when fission power was supposed to be safe and clean?
Slashdot Mirror
The paper said that one of the targets that apparently was affected was 150 m from the "generator".. Would be pretty nifty vibrations that caused a target 150m away in another building to move 14cm sideways...
A single, sharp impulse might do it, and IMO that's more likely than a gravity beam.
However, looking over the links other posters have supplied, I suspect fraud is the most likely explanation.
While I question the researchers' conclusions, if the effects they claim to observe occurred, it's probably worth trying to duplicate the experiment. If nothing else, it would teach us about how to properly shield and isolate discharge rigs to prevent spurious effects like they saw, and at best there might even be something new going on here.
My personal suspicion is that either their Faraday cage was flawed, or they neglected to put the capacitor bank in the cage (the whole discharge circuit loop will act as an induction coil), or that they neglected to put both the discharge rig (with bank) and the test jars on vibration isolation tables (send a current pulse through a loop of cabling, and the cabling will *vibrate*).
That, or the observations are false or embellished.
Either way, the experiment is easy to duplicate (they were very good about describing their apparatus and methods), and there are quite a few points where more thorough control would help pin down the nature of whatever's happening. It's cheap enough, so I can see a university's physics department doing it for a lark. This is exactly how science should work.
Silver Fluoride (the substance the article is talking about) is often used by dentists for fluoride treatments on weakened teeth.
Actually, no. The article talks about a very different type of silver compound.
Silver fluoride has silver as the cation and fluorine as the anion.
A fluoroargentate has something else as the cation (sodium and potassium were mentioned in the article), and AgFx as the anion (AgF3 and AgF4 were mentioned in the article). This is same style of compound as phosphates, nitrates, and so forth, but with an exotic, less stable anion.
Forgot another ongoing cost - making new revisions of a chip to fix bugs or reduce power consumption or better tune the chip to the fab process used. Chips need just as much ongoing maintenance and tinkering as software does, even if the first version runs adequately.
Again, just like software debugging, this sucks up a vast amount of time and effort and resources for the manufacturer.
One reason a company makes the premium product higher is because they need to recover R&D on that product, however I don't see why this is in the chip market. I honestly feel that Intel and AMD "milk" the market for these gurus/morons knowing they will always buy the greatest. So they release a 1.0ghz and these people get that, then they release 1.1ghz and they get this one, etc etc. Although AMD has the 1.0 and 1.1 developed at the same time, they strategically release the products to the general pulic to maximize their profits.
It's quite possible that they _need_ to do this continuously to recover the R&D costs and other overhead costs.
Chip cad/simulation tools cost $0.5M-$1M per _seat_. Prototyping runs cost $300k+ each. The test gear and special-purpose simulation rigs aren't cheap either. A fabrication plant costs over $1B to build, which must be amortised over all chips manufactured there until the next major fab overhaul (typically only 2-3 years away).
Chip design and manufacture is _expensive_. I seriously doubt that they're gouging as badly as you seem to feel they are.
(In case you're wondering how smaller low-end x86-makers survive - they outsource their fabrication, which saves on amortized fab costs and capital at the cost of not having a fab process optimized for their chips (taking a performance hit). If they're wise, they'd also design their chips to either be more robust, or more easily tested, or both, to cut down on simulation/testing costs at the expense of performance.)
I also have to wonder about the validity of these emails and message board posts that show up on shows like CNN's 'talkback live' or 'news site'. Not trying to sound like a conspiracy nut, but we know the media massages news to their liking, how are we to know that they dont try to portray joe six-pack as being in favor or against said subject?
This happens in dead-tree publications on a routine basis, so I'd be surprised *not* to see it in online publications that let the admins - as opposed to the users - choose which replies have prominence.
[User-moderated boards have their own problems, as we all know.]
In the publications around here (Toronto, Canada), papers will typically print "letters to the editor" that either a) continue an existing argument amongst readers, or b) provoke a flood of replies. Note that sanity and accuracy are not listed as requirements; they're an incidental side effect. Sometimes.
The purpose of the letters section is the same as any other section of the newspaper (other than ads) - to get people reading and keep people reading. Not to be accurate for accuracy's own sake.
Astroturfing and other message forgery is still illegal, but selective filtering is standard practice.
This is just a stock SH4 machine with custom peripherals. *BSD has been ported to many such devices, and so has Linux (Dreamcast being the first that comes to mind, but there are SH4-based PDAs which are probably supported too).
... to develop" a device like this. They look serious about it, but for now, it's still vapour.
If demand exists, and if the product rolls out in quantity at a decent price point, distributions for pick-your-favourite-*NIX will be out in short order.
Bear in mind that all we've seen as a "license agreement
The article reads like a summary of all of the non-lethal crowd control ideas that have been endlessly bandied around during the last couple of decades.
Crowd control techniques that are conspicuously absent from real use.
The problem is that things like lasers and sonic weapons and electrified water guns are more expensive and/or more difficult to keep non-lethal than good old-fashioned tear gas and pepper spray and firehoses.
Lasers blind people. Sonic weapons turn their bowels to jelly, harm internal organs, or both. Electrified water guns have nasty effects on anyone with a pacemaker or just a weak heart. And so forth.
With increased cost and increased number of lawsuits, I don't see why any riot-control force would use them.
Ok, so what's the payload to orbit for this six foot rocket?
:).
Payload for a six-foot rocket would be about 5 kg (10 lbs) or so, assuming that 1% of the rocket's mass is cargo. This is a conservative estimate.
You can fit many kinds of research satellite into this weight restriction. Sensor, camera, and Earth-observing telescope packages don't have to be that large or heavy, and as long as you have a large ground station to handle communications, the satellite's power requirements will be low.
It would be tempting to try to launch something like a low-earth-orbit cell phone repeater, but you'd need a much heavier satellite for that (a communications satellite uses a lot of power).
Right now small satellites like I've described are already used; they're just launched in the leftover cargo space on larger rockets, or in large groups from larger rockets that a coalition of users buys space on.
Why has nobody built a small payload launch facility at altitude somewhere that there is a mountain range on a tropical east coast? Because while 20 miles is good, 2 miles is still above a lot of the atmosphere, no? Just political reasons?
Mainly because the payoff doesn't justify the cost. At 2 miles, you'd still have about 70% of the atmosphere above you, so your rocket would still be quite large. And if you can afford to build a rocket base on top of a mountain and transport rockets there, you can afford to build big rockets in the first place, and don't have a problem with atmosphere thickness
Good thought, though.
it would still be nice to see people aiming for orbit.
Agreed.
A rocket that could launch a human's worth of cargo would probably be big enough that you could launch it from the ground (and be expensive as all heck, alas).
So this group has figured that in getting to 120km of altitude, the atmosphere is a big part, so a baloon can make the difference. Great, but what use is it in getting us closer to private space ventures, which is what the X prize was supposed to be about?
It's useful because the same technique lets you build much smaller orbital spacecraft.
To have enough delta-v to reach orbit with chemical fuels, your rocket has to be mostly fuel (between 90% and 95%, depending on the specific impulse of the fuel).
The strength-to-weight ratio of your rocket's frame gets better as your rocket gets smaller. This makes it much easier to build, say, a six-foot rocket that's 95% fuel than a 60-foot rocket that's 95% fuel.
Your rocket will lose energy as it plows through the atmosphere. As you make the rocket bigger, this becomes less of a problem. The balance point is where the cross-sectional mass of your rocket (mass per unit cross-sectional area) becomes greater than the cross-sectional mass of the column of air that it's plowing through.
At sea level, that's about 10 tons per square yard. Your rocket has to be about 30 feet high to reach the balance point, and would ideally be much larger. This will be a big, expensive rocket, and making it 95% fuel will be difficult.
Go up 20 miles or so, and you're above 90% of the atmosphere. The tradeoff point happens when your rocket is 3 feet long. Remember how I said building a 6-foot rocket that's 95% fuel is easier than building a 60-foot one? You could build something like this in a garage. All you need to have an orbit-capable mini-rocket is a way to bring the launch platform 20 miles into the air.
A mini-rocket would still be very commercially viable. Do a web search for "nanosat" and "picosat" to find projects that could be launched on a rocket this size.
A balloon is a great way to do this. Various types of powered aircraft might be able to make the trip too.
*That* is the benefit of this type of project - researching a practical launch platform that could be used for small, orbit-capable rockets.
No, my little minions of evil don't have to have any intelligence at all, they merely have to be able to make random changes in themselves and be able to evaluate those changes in regards to a given set of hostile conditions.
...And this feeds back to the whole Gray Goo question: _can_ nanobots be built that could turn most matter into copies of themselves?
I personally think that this is very unlikely to be a problem. Special-purpose nanobots - e.g. ones optimized for construction given external power and matter supplies - can be very efficient. General-purpose nanobots would be less so. If you try to adapt a nanobot to the task of replicating as much as possible using ambient sources of matter and energy, you'll get something with performance characteristics much like existing replicators with similar design goals - bacteria.
I have yet to see a convincing argument that general-purpose nanomachines could be more efficient than bacteria at spreading and transforming the world about them. Both have abundant supplies of raw material, but both are limited by energy and by competition with other life forms.
But, we are talking about nanobots here, they would most likely have the ability to replicate themselves, and why replicate an inherit design flaw, like a dependance on something?
Easy - because they're too dumb to modify their own designs.
Designing a system that can design or improve the design of systems as complicated as itself is another task that's comparable to solving the Strong AI Problem.
You could argue that mutations might let them evolve, eventually, but nanomachines would be much less suceptible to mutation than biological replicators (by design - you don't want a cosmic ray to cause future generations of nanobots build houses without foundations, for instance).
You'd probably give nanobots the hard-coded pattern for replicating themselves, and the ability to download large structure designs from your database when building things. That way you don't have to give your nanobots the designs for every structure you could conceivably want to build, and they wouldn't have to do any design work at *all*.
Now, someone could deliberately build nanobots that would try to replicate ad infinitum, but that's for another thread.
How much energy is needed to power this thing? And isn't there a lot of energy released when the positrons finally hit some electrons? Or does that energy get reabsorbed somehow?
The positrons produce gamma rays when they are finally annihilated in the target, which will ultimately end up as heat in your radiation shielding.
The positron source is a radioactive isotope that naturally emits positrons. This means that the total amount of energy involved will be quite low (very few positrons). It's a testament to the engineering skill of the people who built the microscope that they can get the results they do, with such a small number of positrons.
The radioactive isotope is probably produced by sticking a container of appropriate source material into a fission reactor's core for a few hours/days/weeks. That's how most medical isotopes are produced.
Why not adopt the three laws of Robotics?
Because making the nanomachines understand the Three Laws requires a solution to the Strong AI Problem. This will not be a cakewalk, and will be overkill for the vast majority of applications of nanomachines.
Building in an "off" switch or a dependence on a specific environmental factor would work at least as well and would be far easier.
Hahahah. It's not total bullshit, but how many users do you honestly think know how to compile something (as easy as it may be)?
That's why the web sites of large applications offer binaries compiled for multiple platforms and linux versions.
All you'd need to do would be to convince them to make builds for pick-your-favourite-platform.
Alternatively, you could find one dedicated person to build all of the apps you want to use for the target machine, and host their own site with the packages for the masses to download.
Installation will still likely be a pain, but the user won't have to futz around compiling things.
Linux PPC which has no apps
But isn't the beauty of Open Source the fact that you can just acquire and compile any needed programs for your favorite platform? Or is that just propaganda bullshit?
If the code was written cleanly, you can do it with a simple recompile.
If the code makes assumptions about, say, the endianness of the machine or the number of bits in a word, then it will probably break.
Whether a given piece of code is cross-platform-safe or not is luck of the draw (you're hoping that the coder had enough motivation to put in the extra work to make it portable).
If the internal fields remain 'for 15 years' then the power consumption of the chip should hopefully be lower, since the cache shouldn't need power refresh.
:).
Caches already don't need (much) power to refresh. They're made of CMOS SRAM, which means that they only dissipate a lot of power when their state changes (ideally they'd dissipate none when the state isn't changing, but there's leakage current across gates and across junctions to the substrate).
Caches are power-hungry because any access has to a) do a tag lookup and b) propagate itself across the entire cache. There are tricks you can use to reduce the power cost of this, but this will still dominate by far over static power requirements.
Heat generation within both caches and the chip core is mainly caused by changing states and shuffling information around, not by maintaining an existing state. I've been studying this for a few years now
It seems that a lot of people really like this book, and I'm definately going to skim the on-lin version to see if I want to buy it, but I wonder how hard is it for someone with intermediatte experience coding to learn to make drivers? Anyone able to share their ordeals with it?
The first edition of the book was quite good for this; it had many examples of simple drivers scattered within to illustrate what it was talking about, which was very helpful.
My best advice would be to a) write a couple of toy drivers to get a feel for things, and b) take apart an existing driver and see how it works. I wrote an I/O space interface driver that I used to play with parallel ports, and a PCI-scanning driver; both purposes are already served by other parts of Linux, but it was still fun. I also had the dubious joy of wading throught the LML-33 video capture card's driver. I learned a lot by doing both, though, and the book was an invaluable reference.
Yes, light does obey the Inverse Square Law. A laser does not because the light has been manipulated to make the photons travel parallel to each other, thus it does not "spread its influence equally in all directions".
Your laser beam diffracts as it passes through any finite-sized aperture (the laser mirrors count as apertures for this). This causes the resulting beam to diverge (think back to the single-slit diffraction experiment in high school physics class).
A diverging beam can be thought of as a cone. The area of a cone's cross-section goes up as the square of the distance from the origin, so the intensity of the laser light will indeed go down as the inverse square. In a real laser beam, the distribution vs. angle is gaussian instead of uniform, but the same principle applies.
Using a wider beam would result in a narrower cone, but your aperture would have to be at least 10 km wide to have a spot size as small as a planet at a distance of 10 light-years. So, any practical laser would spread out like a cone that covers a lot more area than the target.
What do you think? Are we (Terrans) currently able to target a laser beam on a planet 1, 10, 100 light years away?
Short answer: Yes, but it would be expensive.
Long answer:
Stars and planets have (relatively) easily-plotted courses. Spend a few months with a big telescope, and you can do any fine-tuning you need to in your model of the planet or parent star's trajectory. Put a big beam splitter in front of the telescope, fire a huge, very expensive laser at the beam splitter, and you can send the laser beam to the target system while using the telescope to make sure it's going in the right direction.
Target _system_?
Well, the problem is that your laser's aperture is small enough that diffraction prevents you from focusing it on something as small as a planet over interstellar distances. So you'll probably end up bathing most of the inner system of the destination star in weak laser light. Your laser has to be quite bright to be picked up (even if you pulse it), which means very, very expensive.
Alternatively, you can build an array of many lasers in space, and pull evil tricks to keep them all in phase with each other. This gives you a very large synthetic aperture, which would let you target the laser at a single planet. Of course, you'd need a synthetic aperture optical telescope of comparable size to _track_ the planet, but if you can build the laser, the telescope is within reach also.
This is "stupidly expensive", as opposed to merely "insanely expensive", but it could be done. We'd have to do something similar if we wanted to easily launch sailcraft over interstellar distances.
Does that mean that someone has been actually sent to space using this vehicle?
No. As described in the article, this test was a takeoff followed by a few hundred metres of flight near the ground followed by landing, to see if the craft was airworthy.
*Also* as described in the article, this isn't a craft that can achieve stable orbit. It's intended for sub-orbital flight to orbital altitude, which is a *lot* easier to do. The company feels that tourists will still pay for it. This project also lets them fine-tune their reusable rocket technology.
An impressive and useful engineering project.
If page typesetting doesn't have to be pixel-perfect, clean HTML should be fine. As other posters have pointed out, the look of the document will vary from browser to browser, but for most of the documents I write, that's perfectly acceptable.
If page typesetting _is_ important, how about zipped postscript files? Postscript files are huge, but compressing them solves that problem adequately. This is transparent enough to the user to be acceptable (click on it, and WinZip pops up a nice window with the uncompressed file listed in it).
If you're using the postscript option, it's probably wise to have a link to the Windows version of GhostView on the same page that provides the documents, to minimize viewing hassles. Maybe WinZip too, though most people who download things will have that installed already.
Links to Linux and Mac binaries would be useful too, but Windows support should be the first design priority if this is a commercial site (by sheer force of demographics).
I can just see loading Eliza into this for laughs.
The irony is that an Eliza-like program might actually be a decent enough conversationalist for these purposes.
Please, do not use all the water in the oceans just for fueling the fusion in those power plants... We (mankind) need it as long as we want to actually LIVE on this planet...
You'd only need to take the deuterium for the first million years. Removing 1/7000 of the oceans' water would not cause substantial problems.
anyone with a tenth of an IQ point knows that fusion is clean and safe, unlike fission.
Fusion is certainly safer than fission from a high-level waste point of view, but how exactly do you propose to prevent the reactor vessel from becoming radioactive? Even "relatively few" neutrons is enough to cause major headaches for disposal of replaced parts for a multi-gigawatt reactor.
Claiming that it's perfectly clean will only make backlash worse when the public finally clues in. Remember when fission power was supposed to be safe and clean?