Public key cryptography does not necessarily mean using hardware tokens. Key exchange protocols use public key algorithms without hardware tokens or public key infrastructure by seeding the key exchange algorithm with a password. If the client and the server's passwords match they have a strong shared secret for the session. If they don't - no information has leaked.
These methods are immune to sniffing and offline dictionary attacks and don't require long passphrases to be secure. You just need a password that can't be guessed in the number of attempts allowed by the server.
Examples of such protocols include Bellovin and Merritt's EKE and David Jablon's SPEKE. The Stanford SRP algorithm is related. These methods have been around since 1992. Unfortunately, all of them are patented and none of them is in widespread use. The patent status of SRP is unclear as it may infringe the EKE patent.
You see, new dynamic languages have a choice when they get to a certain point (a choice e.g. python is now facing) - do they add the remaining features of lisp and thereby "risk" being classed as a reinvented dialect of lisp, or refuse those features, maintain their independent identity, but forever cripple their language compared to lisp?
Sheesh. The amount of arrogance in that sentence is almost making me reel with dizzyness.
Do you actually imagine that all the smart people behind languages such as Python are ignorant of lisp's other features and that's the only reason they haven't adopted them yet? It is absolutely possible to learn certain things from lisp while rejecting others with well thought-out rationale.
BTW, Python is on its way to become somewhat LESS lisp-like. For example, functional programming builtins such as map, filter and reduce are going away. Functions would remain first-class objects, of course, and it is trivial to write your own version of these functions or import them from some backward-compatibility library. But it will not be in the builtins because it's not easy to read this kind of code. List comprehensions are much more straightforward than map and filter. They are readable the first time you encounter them without explanation. And reduce is barely used for anything but calculating sums anyway.
I think Lynn's implementation is much simpler. The slowly-rotating cable described in the article requires huge gears to produce energy (gears are already a problem on standard large-diameter wind turbines). Lynn's design uses an efficient, high-speed turbine on the kite itself and transmits the power down through the tether. Instead of a complicated circle of kites he uses just one big kite that flies around in circles on a single tether. The turbine can be powered from the ground and used as a propellor to take off, land and keep aloft during lulls in the wind.
Fuel is an insignificant item on the total cost of a space mission - typically less than 1%. The biggest recurring cost is payroll for the standing army of technicians (and their managers). This number is particularly high because it's divided by a pretty small number of launches per year. Another huge cost (if you care to count it) is the development cost, amortized over a small number of launches.
"Well, do bear in mind that NASA Administrator is basically a political job. Jim Webb didn't know diddly about the technical issues, but he was still probably the best Administrator NASA ever had, because he knew where the bodies were buried in Washington."
Quoted from the the one and only Henry Spencer (1993)
Garbage collection prevents certain classes of memory leak. It has nothing to do with buffer overflows.
Your comment is correct from a nitpicking point of view. As a language design choice, garbage collection and range checking are virtually always implemented (or not implemented) together. Having no range checking can easily bring down the entire garbage collection system by corrupting its structures. Range checking by itself doesn't help much if the pointer you are range-checking is a stale reference to deallocated data.
The adjacent story about Portable Firefox and Thunderbird makes me think that a portable AbiWord could be useful, too. If you carry your documents around on a USB flash disk it would make a lot of sense to take along the word processor capable of editing them and not require it to be installed on the target machine.
I remember Potty Pigeon had a wonderful adaptation of Chopin's Funeral March when your pigeon dies. Night falls... the chicks in the nest are left without a parent... I think I'm gonna cry...
In a cold weather areas the waste heat indeed counts against your heating bill so that energy is "free" and LEDs appear less attractive.
But in areas where air conditioning is the rule LEDs are a particularly good deal. Your energy savings will be well over twice the waste heat because it takes more than 1 watt of air conditioning power to remove 1 watt of waste heat.
I have heard the new terminal in Israel's international airport is lit by LEDs, probably for this reason.
Spammers often register their domains without proper contact details. They can't get the notice. Some spam vigilantes could, (um... theoretically, of course...) hijack these domains to teach the spammers a lesson.
For an entertainment PC the rear speakers need to be connected somehow. Cables across the living room have a very low Wife Acceptance Factor. You can probably find power outlets on that side of the room, though.
This way you can install an entertainment PC as a suprize guerilla warfare move without cable infrastructure that requires advance negotiations.
I used to work in the PC audio industry. About 6 years ago and we worked on wireless speakers. It was probably a bit premature, though.
Suddenly, you've got nearly 2 TB of data that is completely unreadable by normal controllers, and you can't replace the broken one! Oops!
This is also a good reason to use mirroring rather than fancier schemes like striping or RAID-5, if you can afford the capacity hit. You can always mount the drive individually.
Get a diving supplies shop to make you a sleeve of thick neoprene according to your specification. With the laptop inside it you can just throw it into amy backpack and virtually nothing could harm it. It's a good solution for smaller notebooks. Bigger laptops probably need a dedicated bag.
Suddenly that old commercial advertisement for a Hilton Hotel in space doesn't sound so wacky anymore. What with Richard Branson investing in the Spaceship One technology for a fleet of commercial spacecraft.
...and Robert Bigelow's Bigelow Aerospace working on inflatable space structures. Robert Bigelow is also the owner of the Budget Suites of America Hotel Chain.
Bigelow has recently announced the logical follow-up to the X-Prize: America's Space Prize, a $50 million prize to build a vehicle capable of taking 7 people to an orbiting space habitat and back before the end of the decade.
Bigelow actually denies any plans for an orbital hotel, but with his background everyone keeps assuming that's his intention anyway.
Almost any of the alternative voting systems is vastly superior to plurality voting. Among them Approval voting is the simplest and easiest to understand and implement.
It's true that Condorcet has some advantages over Approval but these are mostly theoretical and are greatly offset by its complexity.
Going to space and back in a single stage vehicle is extremely difficult because it requires it to be almost completely made of fuel, leaving little mass for thermal protection system, recovery gear, etc (payload?).
Doing it in a multistage vehicle is difficult because it then becomes much harder to reuse it. Even if you ignore the cost issues of throwing away hardware you really want reusability because otherwise every launch you are using brand new hardware with unknown problems. It's hard to get reliability this way.
A lot of the people looking at CATS (Cheap Access To Space) seem to agree that an "assisted" single stage vehicle is the way to go. Starting at high altitude may not give the vehicle significant savings in kinetic and potential energy but other factors such as drag, pressure losses and structural loads can make a very big difference.
There are several promising designs for an assisted SSTO. One example is is Spacevan 2008. It seems to fit the profile of the America's Space Prize very well. The big kite may seem a bit odd but don't be fooled - it's not one of those "designs" that space crackpots keep promoting. It was designed by veteran space engineer Len Cormier. He is one of those people who really know what they are talking about. It's actually a pretty conservative design using mature and proven technology.
Don't get me wrong - the X-43 is a fantastic engineering achievement. It may pave the way for things like a mach 10 airbreathing cruise missile or possibly even a hypersonic jet transport. But it has nothing to do with access to space.
A space launch is a short acceleration mission. You spend very little time at any particular speed. A scramjet is good for efficient and sustained cruising at a certain range of speeds. It's not effective for takeoff. It's not effective for accelaration to supersonic speed. It's not effective for acceleration from supersonic to low hypersonic. It's not effective for accelerating from its top hypersonic speed up to orbital velocity. It's only good for a specific range of hypersonic velocities.
Current plans are talking about using at least three different types of engines to make a single vehicle that can make it all the way to space. This is an enormous penalty in weight, vehicle shape and configuration. It's doubtful if a single vehicle can be designed for all these different flight regimes and still be light enough to make it into space at all. But even if it can be done there is absolutely no way it can be cheaper. The development and operational costs of such a complex system will be staggering.
In short, saying that scramjets are the way to cheaper access to space is a big fat lie and just an excuse for robbing the taxpayers.
It was immediately obvious from the very outset to anyone who spent a little while playing around with the math that there would never be any way to make money from this.
Remember that Iridium Outset = 1987. At that time cellular phones were a specialty item used by high-rolling executives, charge per minute were astronomical and coverage patchy. The investment in Iridium didn't seem more dangerous than, say, the development of a new business jet. It was pretty difficult to imagine that in just a few years prices will drop by orders of magnitude and cellular phones will become a fashion item for schoolkids.
They did assume in their business plan that the prices of ground-based competition will drop, but not by that much.
Support a heterogenous shopping environment where quality, service, support AND price all factors in the purchasing decision
Here's an interesting story about how one company managed to provide outstanding support for its products using a rather extreme form of outsourcing. Vernor Vinge recently won a Hugo award for this story.
Slashdot Mirror
Public key cryptography does not necessarily mean using hardware tokens. Key exchange protocols use public key algorithms without hardware tokens or public key infrastructure by seeding the key exchange algorithm with a password. If the client and the server's passwords match they have a strong shared secret for the session. If they don't - no information has leaked.
These methods are immune to sniffing and offline dictionary attacks and don't require long passphrases to be secure. You just need a password that can't be guessed in the number of attempts allowed by the server.
Examples of such protocols include Bellovin and Merritt's EKE and David Jablon's SPEKE. The Stanford SRP algorithm is related. These methods have been around since 1992. Unfortunately, all of them are patented and none of them is in widespread use. The patent status of SRP is unclear as it may infringe the EKE patent.
You see, new dynamic languages have a choice when they get to a certain point (a choice e.g. python is now facing) - do they add the remaining features of lisp and thereby "risk" being classed as a reinvented dialect of lisp, or refuse those features, maintain their independent identity, but forever cripple their language compared to lisp?
Sheesh. The amount of arrogance in that sentence is almost making me reel with dizzyness.
Do you actually imagine that all the smart people behind languages such as Python are ignorant of lisp's other features and that's the only reason they haven't adopted them yet? It is absolutely possible to learn certain things from lisp while rejecting others with well thought-out rationale.
BTW, Python is on its way to become somewhat LESS lisp-like. For example, functional programming builtins such as map, filter and reduce are going away. Functions would remain first-class objects, of course, and it is trivial to write your own version of these functions or import them from some backward-compatibility library. But it will not be in the builtins because it's not easy to read this kind of code. List comprehensions are much more straightforward than map and filter. They are readable the first time you encounter them without explanation. And reduce is barely used for anything but calculating sums anyway.
Ok, so we learned that it's VTVL. But we still know virtually nothing about it.
Compare it to John Carmack's space effort where you get updates with intimate details about every bolt, valve and crash.
Kitemaster Peter Lynn from New Zealand has a similar design.
Original usenet posting
A page describing the idea
I think Lynn's implementation is much simpler. The slowly-rotating cable described in the article requires huge gears to produce energy (gears are already a problem on standard large-diameter wind turbines). Lynn's design uses an efficient, high-speed turbine on the kite itself and transmits the power down through the tether. Instead of a complicated circle of kites he uses just one big kite that flies around in circles on a single tether. The turbine can be powered from the ground and used as a propellor to take off, land and keep aloft during lulls in the wind.
Fuel is an insignificant item on the total cost of a space mission - typically less than 1%. The biggest recurring cost is payroll for the standing army of technicians (and their managers). This number is particularly high because it's divided by a pretty small number of launches per year. Another huge cost (if you care to count it) is the development cost, amortized over a small number of launches.
"Well, do bear in mind that NASA Administrator is basically a political job. Jim Webb didn't know diddly about the technical issues, but he was still probably the best Administrator NASA ever had, because he knew where the bodies were buried in Washington."
Quoted from the the one and only Henry Spencer (1993)
Garbage collection prevents certain classes of memory leak. It has nothing to do
with buffer overflows.
Your comment is correct from a nitpicking point of view. As a language design choice, garbage collection and range checking are virtually always implemented (or not implemented) together. Having no range checking can easily bring down the entire garbage collection system by corrupting its structures. Range checking by itself doesn't help much if the pointer you are range-checking is a stale reference to deallocated data.
The adjacent story about Portable Firefox and Thunderbird makes me think that a portable AbiWord could be useful, too. If you carry your documents around on a USB flash disk it would make a lot of sense to take along the word processor capable of editing them and not require it to be installed on the target machine.
I remember Potty Pigeon had a wonderful adaptation of Chopin's Funeral March when your pigeon dies. Night falls... the chicks in the nest are left without a parent... I think I'm gonna cry...
In a cold weather areas the waste heat indeed counts against your heating bill so that energy is "free" and LEDs appear less attractive.
But in areas where air conditioning is the rule LEDs are a particularly good deal. Your energy savings will be well over twice the waste heat because it takes more than 1 watt of air conditioning power to remove 1 watt of waste heat.
I have heard the new terminal in Israel's international airport is lit by LEDs, probably for this reason.
"So perhaps this Pentium 4 architecture with its ridiculously deep pipeline wasn't such a great idea after all?"
Spammers often register their domains without proper contact details. They can't get the notice. Some spam vigilantes could, (um... theoretically, of course...) hijack these domains to teach the spammers a lesson.
The risks involved increase polynomially the longer the craft is active.
According to this logic, you wouldn't want to go on an airplane crossing the pacific. It depends on the hardware working perfectly for many hours.
A spacecraft is only really "active" for a few minute on takeoff and landing.
For an entertainment PC the rear speakers need to be connected somehow. Cables across the living room have a very low Wife Acceptance Factor. You can probably find power outlets on that side of the room, though.
This way you can install an entertainment PC as a suprize guerilla warfare move without cable infrastructure that requires advance negotiations.
I used to work in the PC audio industry. About 6 years ago and we worked on wireless speakers. It was probably a bit premature, though.
Suddenly, you've got nearly 2 TB of data that is completely unreadable by normal controllers, and you can't replace the broken one! Oops!
This is also a good reason to use mirroring rather than fancier schemes like striping or RAID-5, if you can afford the capacity hit. You can always mount the drive individually.
Rob Davis is a marketer. He knows the importance of setting an exciting, simple, clearly-defined goal "Get a pull page ad on the NYT".
It's the kind of detail that makes the difference between "yeah, that's cool" and "I'll give some money NOW".
Open source needs more people like that. More ideas like that.
Get a diving supplies shop to make you a sleeve of thick neoprene according to your specification. With the laptop inside it you can just throw it into amy backpack and virtually nothing could harm it. It's a good solution for smaller notebooks. Bigger laptops probably need a dedicated bag.
We've been rather fed up with NASA's castration for years...
Mostly self-inflicted. Ouch.
Bigelow has recently announced the logical follow-up to the X-Prize: America's Space Prize, a $50 million prize to build a vehicle capable of taking 7 people to an orbiting space habitat and back before the end of the decade.
Bigelow actually denies any plans for an orbital hotel, but with his background everyone keeps assuming that's his intention anyway.
Almost any of the alternative voting systems is vastly superior to plurality voting. Among them Approval voting is the simplest and easiest to understand and implement.
It's true that Condorcet has some advantages over Approval but these are mostly theoretical and are greatly offset by its complexity.
Going to space and back in a single stage vehicle is extremely difficult because it requires it to be almost completely made of fuel, leaving little mass for thermal protection system, recovery gear, etc (payload?).
Doing it in a multistage vehicle is difficult because it then becomes much harder to reuse it. Even if you ignore the cost issues of throwing away hardware you really want reusability because otherwise every launch you are using brand new hardware with unknown problems. It's hard to get reliability this way.
A lot of the people looking at CATS (Cheap Access To Space) seem to agree that an "assisted" single stage vehicle is the way to go. Starting at high altitude may not give the vehicle significant savings in kinetic and potential energy but other factors such as drag, pressure losses and structural loads can make a very big difference.
There are several promising designs for an assisted SSTO. One example is is Spacevan 2008. It seems to fit the profile of the America's Space Prize very well. The big kite may seem a bit odd but don't be fooled - it's not one of those "designs" that space crackpots keep promoting. It was designed by veteran space engineer Len Cormier. He is one of those people who really know what they are talking about. It's actually a pretty conservative design using mature and proven technology.
Don't get me wrong - the X-43 is a fantastic engineering achievement. It may pave the way for things like a mach 10 airbreathing cruise missile or possibly even a hypersonic jet transport. But it has nothing to do with access to space.
A space launch is a short acceleration mission. You spend very little time at any particular speed. A scramjet is good for efficient and sustained cruising at a certain range of speeds. It's not effective for takeoff. It's not effective for accelaration to supersonic speed. It's not effective for acceleration from supersonic to low hypersonic. It's not effective for accelerating from its top hypersonic speed up to orbital velocity. It's only good for a specific range of hypersonic velocities.
Current plans are talking about using at least three different types of engines to make a single vehicle that can make it all the way to space. This is an enormous penalty in weight, vehicle shape and configuration. It's doubtful if a single vehicle can be designed for all these different flight regimes and still be light enough to make it into space at all. But even if it can be done there is absolutely no way it can be cheaper. The development and operational costs of such a complex system will be staggering.
In short, saying that scramjets are the way to cheaper access to space is a big fat lie and just an excuse for robbing the taxpayers.
It was immediately obvious from the very outset to anyone who spent a little while playing around with the math that there would never be any way to make money from this.
Remember that Iridium Outset = 1987. At that time cellular phones were a specialty item used by high-rolling executives, charge per minute were astronomical and coverage patchy. The investment in Iridium didn't seem more dangerous than, say, the development of a new business jet. It was pretty difficult to imagine that in just a few years prices will drop by orders of magnitude and cellular phones will become a fashion item for schoolkids.
They did assume in their business plan that the prices of ground-based competition will drop, but not by that much.
Thanks to archive.org an older version of the site with some concept art showing the martians and fighting machines.
The gallery on the new site has no glimpse of anything non-human.
Support a heterogenous shopping environment where quality, service, support AND price all factors in the purchasing decision
Here's an interesting story about how one company managed to provide outstanding support for its products using a rather extreme form of outsourcing. Vernor Vinge recently won a Hugo award for this story.