By computing MD5 hashes of consecutive (overlapping) line triplets, the shred algorithm makes it easy to identify copied code, without ever seeing the actual code. This might be a perfect way for companies to allow a third party to compare code, without giving away any trade secrets in the process.
Of course, since MD5 is a very good cryptographic hash function, *any* one-bit change in the source will result in, on average, half of the bits in the result being flipped. So, this method of identifying copied code would only work if the code had never been run through an obfuscator. It would also be defeatable by running the source through a script to have its variable names search-and-replaced with similar names (such as replacing every variable name with a new name consisting of the old name plus "_newname")....
In short, this might be a useful technique for allowing a third party to look for trivial wholesale copying of code, but it would be useless for finding a motivated miscreant, determined to steal code without being caught.
Actually, there is a market for it. Two, in fact. First, low-G scientific experiments. Second, satellite launches. They already do this with the shuttle---using a booster rocket to kick the thing into a higher geosync orbit. Think of the RSV as a reusable, manned launch platform for satellites. If it could be done in a way that was totally reusable without major refurbishing, it would be a lot cheaper to launch than a Saturn V or something.
Of course, the (disposable) booster stage would be much bigger and more costly than what they use now, but it still might be a win... emphasis on might.:-)
Good point about the possibility of using a disposable booster stage to boost the payload out of the sub-orbital trajectory and into an orbital one. However, I share your skepticism that it could be done cost-effectively. After all, you've just effectively reduced the payload-carrying capacity of your suborbital vehicle by about a factor of 20 or so, as you need to, instead, carry a booster capable of lifting a (much smaller) payload from your suborbital altitude up to a specified orbital one, and then "circularize" the orbit, as well. All that maneuvering takes energy, and it's quite likely to require significantly more than an equivalent "disposable" launch system would use to acheive the same objective.
Also, by including a disposable booster, the complete "launch system" is no longer "reusable", is it? Of course, neither is the current Shuttle, considering the disposable nature of the External Tank.
While the article does make some good points about the high development costs, technological hurdles, and poor ROI on reusable orbital vehicles, I think that there is very little evidence of any solid business case for reusable sub-orbital vehicles. Just because it's not cost-effective to build and fly ROVs doesn't somehow make RSVs any more logical.
As a development step leading to the next ROV, an RSV may make sense. I am the first to admit that *anything* that gets the public to refocus their attention (and money) on the pursuit of space-related technological goals is a good thing, as it will inevitably drive the aerospace industry to push the engineering envelope in many areas, particularly in materials science (things like new composites, high-temperature ceramics, etc.). Technological advancement is a worthy (and, ultimately, profitable) pursuit.
But, in and of itself, as a "working vehicle", I can't see any suborbital spacecraft making money. There just aren't that many rich "space tourists" around to subsidize this as an industry. Suborbital vehicles are completely useless for the two main "space jobs" that countries and/or companies are willing to pay for: satellite launches and trips to the ISS.
Low Earth Orbit (LEO) is a useful destination. If you can get "stuff" into LEO, later trips can bring more "stuff", and, if you bring enough pieces of another space ship to LEO, you can assemble them there, and can go to other places. In terms of energy, LEO is truly "halfway to anywhere". One of the (rejected for complexity and deadline reasons) proposed Apollo moon landing plans involved assembling a Earth-to-Moon ship in LEO from modules launched over a period of time using multiple smaller launchers.
But, suborbital vehicles, by definition, can't reach LEO. Anything launched sub-orbitally *will* return to Earth, usually sooner, rather than later. There's simply no market for delivery vehicles that always bring their cargo back, and never leave it at the destination!
Bottom line: it may make sense to use an RSV as a technology test-bed as a step on the path to developing an ROV. It makes no sense to develop an RSV as an end in itself.
All science fiction, to some extent, fictionalizes science. In other words, there will always be some aspects of any given science fiction tale that are not scientifically valid. All fiction, in fact, relies upon the "willing suspension of disbelief" by the audience, to some extent or another.
We allow ourselves to go along with the author's contra-factual assumptions, to see where they lead the story, and to allow ourselves to become engaged by a tale of a world almost, but not quite, like our own.
The best science fiction tales, in my opinion, are those in which the author respects this effort on the part of his audience, and doesn't ask them to suspend disbelief unnecessarily. For example, look at any of Robert L. Forward's novels. He may ask you to believe, for the purpose of his story, that life (of some sort) could exist on the surface of a neutron star. But, beyond that one assumption, he builds an entirely consistent fictional universe, and weaves an interesting story around those creatures, and the first human crew that encounters them.
While there is a lot of bad science in bad science fiction, there's also plenty of good science in good science fiction.
I agree that the crime-rate statistics are meaningless in the context of justifying and/or opposing gun ownership, but for a far different reason.
The framers of the US Constitution were smart men. They had recently fought a war against an oppressive regime, winning their freedom by fighting tooth and nail to do so. They had also recently discovered that their first attempt at a replacement government had failed (see "Articles of Confederation"). They knew, on a gut level, that governments *can* be replaced, and may *need* to be replaced when they no longer exist to serve the people.
The second ammendment to the US Constitution was an attempt to guarantee that the people would always have the means available to replace the government again, in the future, should it become necessary to do so. They'd already done so twice; there was (and is) no reason to suspect that that would be the last time.
Regardless of what is written on paper, the fact will always remain that all governments govern solely by the consent of the governed. When the people get sufficiently fed up with the way their current covernment treats them, they can (and do) replace their government. Guaranteeing them access to the tools necessary to do so is just smart planning on the part of the framers; if the government knows you can fight back, they're (hopefully) less likely to do the sort of things that would make you want to do so.
> Congress trampling all over your civil liberties? Not really. A hacker can't listen to > you unless the FBI already did, in which case you're probably screwed anyway:)
> I'm not saying this shouldn't be fixed, I'm saying it's not a big deal.
Unfortunately, if a hacker gets root on the CALEA boxes, what's to stop him from initiating *new* wiretaps? Yes, he could copy existing files containing recordings made under "legit" wiretap orders. But, what's to stop him from using the *same* methods that the "legit" users do to obtain wiretap recordings of ANYONE he wants?
Interesting that you should say that, because I thought I was (for the most part) disagreeing with your position.
My "Absolutely" was directed towards your question about whether I would allow children to read anything they wanted in an unrestricted bookstore. Correct me if I'm wrong, but I read your comment as implying you were against such a thing happening. I happen to be emphatically in favor of encouraging children to do exactly that.
If we actually do agree, then please forgive me for misunderstanding your position.
- Rick "Polite on/.? What's the world coming to?" Dickinson
Another option would be to sue (or seperate) any parents that let their children browse the web unsupervised... don't want to be old fashioned, but would you let your 10 year old child to read what they liked in an unrestricted bookstore? The parents would be seperated from their kids. And that's what the internet is (much as AOL may try to disagree). Any parents who view their children as impressionable but let them run amock on the internet should be locked up themselves.
Absolutely. I think that children should be allowed to read anything that interests them. Nothing is healthier for a child than unrestricted intellectual curiousity.
Of course, the really good parents are the ones that read with their children, and make sure they are available to answer questions and to suggest reading material that the kids might find interesting and challenging.
You get what you reward.
Treat your children like amoral imbeciles who need their hands held to prevent them from being "corrupted", and you'll end up raising amoral imbeciles who need their hands held to prevent them from being "corrupted".
Treat them like intelligent, ethical adults, and you'll end up raising intelligent, ethical adults.
Why is this so complicated for people to figure out?
- Rick "Parental responsibility is unfashionable, I guess" Dickinson
If you want to be brutally practical, the ultimate reason for space exploration is simple: survival of the human species.
Species are able to survive disasters that strike their ecological niches by the simple expedient of being elsewhere. When a flood wipes out all of the creatures living in one particular meadow, the creatures in the next meadow over carry on as though nothing had happened.
Given the fact that, on a sufficiently long time scale, the odds of a worldwide ecological disaster (such as a "planet killer" asteroid, or a nuclear war) eventually approach certainty, it's absolutely imperative for the survival of "earthlings" that we start working towards a goal of spreading out, and taking steps to move beyond this one rock.
Disasters do happen, however infrequently. As every good sysadmin knows, it's not a matter of if, it's a matter of when.
Let's plan for the big one, and set up a RAIL (Redundant Array of Independent Lifeforms).
While I understand that selecting a successor to the Space Shuttle is an important task, there is a much more important issue at hand: where will NASA get its next generation of visionary rocket scientists, to take us to Mars and beyond?
Many current NASA astronauts, scientists, and technicians first became interested in space exploration as a result of the "Space Race" in the 60s, and, later, grew and maintained their interest thoughout their adolescence by participating in the hobby of model rocketry.
After the space race ended, model rocketry started to decline, but the emergence of high power rocketry in the 80s and 90s revitalized the hobby, and brought back many "Born Again Rocketeers", or BARs, into the hobby; these are people who flew model rockets as kids, and rediscovered the hobby later in life. Many of these BARs are now introducing the hobby to a new generation, and passing on their inspiration.
Now, in the middle of a resurgence of interest, the hobby is in danger of being killed by overzealous overregulation. Due to a combination of misclassification of the most common hobby rocket propellant (Ammonium Perchlorate Composite Propellant) as an explosive (instead of a flammable solid) by ATF, and background checks being mandated by the Homeland Security Act for any employees of companies that ship explosives, shippers like UPS have decided to stop carrying "explosives" altogether, meaning that rocket motors are now virtually impossible to ship, even by UPS ground.
Bottom line, this, and other similar regulations, are leading to the demise of rocketry as a safe, educational hobby. The next generation of rocket scientists will simply not exist.
However, there is hope. Efforts are underway to push a bill through Congress to explicitly exempt the materials used in the hobby of rocketry, when they are used for rocketry (i.e.: non-weapon) uses.
What is needed is a groundswell of support from concerned citizens, supporting this effort. There are complete details on this effort at http://www.space-rockets.com/congress.html, along with a number of talking points you may wish to incorporate into faxed letters to your Senators.
The bill hasn't been introduced yet, but should be this week some time. If you decide to join in, and send a letter, please wait until the notice is posted on http://www.space-rockets.com/congress.html before doing so. That way, the messages will have the most effect (and your senator may have some idea what you're talking about, as there will be a bill on the subject up for debate...).
If you want to help keep the dream alive, I encourage you to read the background info at that site, and join in this worthy effort.
Slashdot Mirror
By computing MD5 hashes of consecutive (overlapping) line triplets, the shred algorithm makes it easy to identify copied code, without ever seeing the actual code. This might be a perfect way for companies to allow a third party to compare code, without giving away any trade secrets in the process.
Of course, since MD5 is a very good cryptographic hash function, *any* one-bit change in the source will result in, on average, half of the bits in the result being flipped. So, this method of identifying copied code would only work if the code had never been run through an obfuscator. It would also be defeatable by running the source through a script to have its variable names search-and-replaced with similar names (such as replacing every variable name with a new name consisting of the old name plus "_newname")....
In short, this might be a useful technique for allowing a third party to look for trivial wholesale copying of code, but it would be useless for finding a motivated miscreant, determined to steal code without being caught.
Actually, there is a market for it. Two, in fact. First, low-G scientific experiments. Second, satellite launches. They already do this with the shuttle---using a booster rocket to kick the thing into a higher geosync orbit. Think of the RSV as a reusable, manned launch platform for satellites. If it could be done in a way that was totally reusable without major refurbishing, it would be a lot cheaper to launch than a Saturn V or something.
:-)
Of course, the (disposable) booster stage would be much bigger and more costly than what they use now, but it still might be a win... emphasis on might.
Good point about the possibility of using a disposable booster stage to boost the payload out of the sub-orbital trajectory and into an orbital one. However, I share your skepticism that it could be done cost-effectively. After all, you've just effectively reduced the payload-carrying capacity of your suborbital vehicle by about a factor of 20 or so, as you need to, instead, carry a booster capable of lifting a (much smaller) payload from your suborbital altitude up to a specified orbital one, and then "circularize" the orbit, as well. All that maneuvering takes energy, and it's quite likely to require significantly more than an equivalent "disposable" launch system would use to acheive the same objective.
Also, by including a disposable booster, the complete "launch system" is no longer "reusable", is it? Of course, neither is the current Shuttle, considering the disposable nature of the External Tank.
While the article does make some good points about the high development costs, technological hurdles, and poor ROI on reusable orbital vehicles, I think that there is very little evidence of any solid business case for reusable sub-orbital vehicles. Just because it's not cost-effective to build and fly ROVs doesn't somehow make RSVs any more logical.
As a development step leading to the next ROV, an RSV may make sense. I am the first to admit that *anything* that gets the public to refocus their attention (and money) on the pursuit of space-related technological goals is a good thing, as it will inevitably drive the aerospace industry to push the engineering envelope in many areas, particularly in materials science (things like new composites, high-temperature ceramics, etc.). Technological advancement is a worthy (and, ultimately, profitable) pursuit.
But, in and of itself, as a "working vehicle", I can't see any suborbital spacecraft making money. There just aren't that many rich "space tourists" around to subsidize this as an industry. Suborbital vehicles are completely useless for the two main "space jobs" that countries and/or companies are willing to pay for: satellite launches and trips to the ISS.
Low Earth Orbit (LEO) is a useful destination. If you can get "stuff" into LEO, later trips can bring more "stuff", and, if you bring enough pieces of another space ship to LEO, you can assemble them there, and can go to other places. In terms of energy, LEO is truly "halfway to anywhere". One of the (rejected for complexity and deadline reasons) proposed Apollo moon landing plans involved assembling a Earth-to-Moon ship in LEO from modules launched over a period of time using multiple smaller launchers.
But, suborbital vehicles, by definition, can't reach LEO. Anything launched sub-orbitally *will* return to Earth, usually sooner, rather than later. There's simply no market for delivery vehicles that always bring their cargo back, and never leave it at the destination!
Bottom line: it may make sense to use an RSV as a technology test-bed as a step on the path to developing an ROV. It makes no sense to develop an RSV as an end in itself.
All science fiction, to some extent, fictionalizes science. In other words, there will always be some aspects of any given science fiction tale that are not scientifically valid. All fiction, in fact, relies upon the "willing suspension of disbelief" by the audience, to some extent or another.
We allow ourselves to go along with the author's contra-factual assumptions, to see where they lead the story, and to allow ourselves to become engaged by a tale of a world almost, but not quite, like our own.
The best science fiction tales, in my opinion, are those in which the author respects this effort on the part of his audience, and doesn't ask them to suspend disbelief unnecessarily. For example, look at any of Robert L. Forward's novels. He may ask you to believe, for the purpose of his story, that life (of some sort) could exist on the surface of a neutron star. But, beyond that one assumption, he builds an entirely consistent fictional universe, and weaves an interesting story around those creatures, and the first human crew that encounters them.
While there is a lot of bad science in bad science fiction, there's also plenty of good science in good science fiction.
I agree that the crime-rate statistics are meaningless in the context of justifying and/or opposing gun ownership, but for a far different reason.
The framers of the US Constitution were smart men. They had recently fought a war against an oppressive regime, winning their freedom by fighting tooth and nail to do so. They had also recently discovered that their first attempt at a replacement government had failed (see "Articles of Confederation"). They knew, on a gut level, that governments *can* be replaced, and may *need* to be replaced when they no longer exist to serve the people.
The second ammendment to the US Constitution was an attempt to guarantee that the people would always have the means available to replace the government again, in the future, should it become necessary to do so. They'd already done so twice; there was (and is) no reason to suspect that that would be the last time.
Regardless of what is written on paper, the fact will always remain that all governments govern solely by the consent of the governed. When the people get sufficiently fed up with the way their current covernment treats them, they can (and do) replace their government. Guaranteeing them access to the tools necessary to do so is just smart planning on the part of the framers; if the government knows you can fight back, they're (hopefully) less likely to do the sort of things that would make you want to do so.
...with a Beowulf cluster of patent lawyers!
Sorry - wrong joke.
- Rick
This ofcourse holds untill the density goes (quite abruptly) up to that of solid rock, at which point velocity goes down to zero.
Yep. That lithospheric friction's a bitch.
- Rick
> Congress trampling all over your civil liberties? Not really. A hacker can't listen to :)
> you unless the FBI already did, in which case you're probably screwed anyway
> I'm not saying this shouldn't be fixed, I'm saying it's not a big deal.
Unfortunately, if a hacker gets root on the CALEA boxes, what's to stop him from initiating *new* wiretaps? Yes, he could copy existing files containing recordings made under "legit" wiretap orders. But, what's to stop him from using the *same* methods that the "legit" users do to obtain wiretap recordings of ANYONE he wants?
Just something to think about....
- Rick
This abundant, unavailable hydrogen thing make me laugh, kind of like "water, water everywhere, but not a drop to drink".
OK, pet peeve time. If you're going to quote poetry, at least quote it correctly:
- Rick "Pedant" Dickinson
Uber Banker wrote:
/.? What's the world coming to?" Dickinson
Damn right, you expressed it really well.
Interesting that you should say that, because I thought I was (for the most part) disagreeing with your position.
My "Absolutely" was directed towards your question about whether I would allow children to read anything they wanted in an unrestricted bookstore. Correct me if I'm wrong, but I read your comment as implying you were against such a thing happening. I happen to be emphatically in favor of encouraging children to do exactly that.
If we actually do agree, then please forgive me for misunderstanding your position.
- Rick "Polite on
Uber Banker (655221) posted:
Another option would be to sue (or seperate) any parents that let their children browse the web unsupervised... don't want to be old fashioned, but would you let your 10 year old child to read what they liked in an unrestricted bookstore? The parents would be seperated from their kids. And that's what the internet is (much as AOL may try to disagree). Any parents who view their children as impressionable but let them run amock on the internet should be locked up themselves.
Absolutely. I think that children should be allowed to read anything that interests them. Nothing is healthier for a child than unrestricted intellectual curiousity.
Of course, the really good parents are the ones that read with their children, and make sure they are available to answer questions and to suggest reading material that the kids might find interesting and challenging.
You get what you reward.
Treat your children like amoral imbeciles who need their hands held to prevent them from being "corrupted", and you'll end up raising amoral imbeciles who need their hands held to prevent them from being "corrupted".
Treat them like intelligent, ethical adults, and you'll end up raising intelligent, ethical adults.
Why is this so complicated for people to figure out?
- Rick "Parental responsibility is unfashionable, I guess" Dickinson
If you want to be brutally practical, the ultimate reason for space exploration is simple: survival of the human species.
Species are able to survive disasters that strike their ecological niches by the simple expedient of being elsewhere. When a flood wipes out all of the creatures living in one particular meadow, the creatures in the next meadow over carry on as though nothing had happened.
Given the fact that, on a sufficiently long time scale, the odds of a worldwide ecological disaster (such as a "planet killer" asteroid, or a nuclear war) eventually approach certainty, it's absolutely imperative for the survival of "earthlings" that we start working towards a goal of spreading out, and taking steps to move beyond this one rock.
Disasters do happen, however infrequently. As every good sysadmin knows, it's not a matter of if, it's a matter of when.
Let's plan for the big one, and set up a RAIL (Redundant Array of Independent Lifeforms).
While I understand that selecting a successor to the Space Shuttle is an important task, there is a much more important issue at hand: where will NASA get its next generation of visionary rocket scientists, to take us to Mars and beyond?
Many current NASA astronauts, scientists, and technicians first became interested in space exploration as a result of the "Space Race" in the 60s, and, later, grew and maintained their interest thoughout their adolescence by participating in the hobby of model rocketry.
After the space race ended, model rocketry started to decline, but the emergence of high power rocketry in the 80s and 90s revitalized the hobby, and brought back many "Born Again Rocketeers", or BARs, into the hobby; these are people who flew model rockets as kids, and rediscovered the hobby later in life. Many of these BARs are now introducing the hobby to a new generation, and passing on their inspiration.
Now, in the middle of a resurgence of interest, the hobby is in danger of being killed by overzealous overregulation. Due to a combination of misclassification of the most common hobby rocket propellant (Ammonium Perchlorate Composite Propellant) as an explosive (instead of a flammable solid) by ATF, and background checks being mandated by the Homeland Security Act for any employees of companies that ship explosives, shippers like UPS have decided to stop carrying "explosives" altogether, meaning that rocket motors are now virtually impossible to ship, even by UPS ground.
Bottom line, this, and other similar regulations, are leading to the demise of rocketry as a safe, educational hobby. The next generation of rocket scientists will simply not exist.
However, there is hope. Efforts are underway to push a bill through Congress to explicitly exempt the materials used in the hobby of rocketry, when they are used for rocketry (i.e.: non-weapon) uses.
What is needed is a groundswell of support from concerned citizens, supporting this effort. There are complete details on this effort at http://www.space-rockets.com/congress.html, along with a number of talking points you may wish to incorporate into faxed letters to your Senators.
The bill hasn't been introduced yet, but should be this week some time. If you decide to join in, and send a letter, please wait until the notice is posted on http://www.space-rockets.com/congress.html before doing so. That way, the messages will have the most effect (and your senator may have some idea what you're talking about, as there will be a bill on the subject up for debate...).
If you want to help keep the dream alive, I encourage you to read the background info at that site, and join in this worthy effort.
Thanks,
- Rick "Rocket Geek" Dickinson