Of course, this is just the start of a much bigger picture, that'll see the filing system become something akin to a searchable knowledge store. Unfortunately, it's not going to happen quickly. For starters, if you were to suggest to the maintainer of app foo that they should store their data as lots of small files, they's say "no way, some of my users are on ext3, or xfs, or jfs" etc.
If it wasn't beneficial to existing creative entities to draw upon shared cultural history residing in the public domain, such creative entities wouldn't do so already.
As much as I don't want to accept that Mickey Mouse should enter the public domain, I can't help but notice that The Little Mermaid has a bit more to her than shellfish and a talking crab sidekick.
In my mind, the bottom line is that every dollar Disney has ever made mining the public domain is concrete proof that there's value to having one. One could make the argument that a creation as actively maintained as Mickey Mouse should be granted a special exemption -- and I might even buy that, based on the idea that there's no sense dragging 20th century creative works into obscurity (and make no mistake, that's where they'll go!) so that one work might keep its trademarkability.
But I don't think it's possible to argue the public domain is useless. If it was, Disney Wouldn't Keep Using It.
Pop Art didn't begin with Warhol.
Yours Truly,
Dan Kaminsky
DoxPara Research
http://www.doxpara.com
video games give us the feel that we are part of the action
Who's us?
See, here's how it works:
"I watch movies. Don't touch my movies. I don't play video games. Fuck video games."
It's just that simple. "I drive. I don't smoke. I skydive. I don't gamble. I drink, but not so much that I get drunk. I tend to hang out in groups of three to seven people. I enjoy sports. Whatever I do must be legal. Ban whatever I'd never do, fine by me."
Yours Truly,
Dan Kaminsky
DoxPara Research
http://www.doxpara.com
Broadcast w/ Verification for SHM updates
on
Ask Donald Becker
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· Score: 2
I can imagine an interesting architecture for SHM coherency involving L2 Broadcast as the backhaul and random hash broadcasts for most-recent-update-received synchronization. As long as updates are reasonably rare, this can work astonishingly well, though I must admit writes will inevitably block for significantly longer periods of time than they otherwise would locally. Fits in well with some other packet mangling I'm doing...toss me a mail, will ya?
Of course, the obvious approach of only migrating processes and not the shared memory it allocated (instead using SHM-over-TCP-maybe-with-SEQ#'s-directly-mapping-to -the-2GB-space) also should work.
--Dan www.doxpara.com
Memory-Oriented Logic
on
Ask Donald Becker
·
· Score: 5, Interesting
Dr. Becker,
As I'm sure you've noticed, the price of memory has been driven into the ground -- indeed, it's so inexpensive, the economics seem to have rendered the usage of virtual memory nearly obsolete. Need another 256MB? Spend the $20 and buy it. It's just that simple.
Now, memory makers can't let their goods be absolutely commodified forever, and I'm unconvinced that further speed increases, either in latency or bandwidth, will remain permanently relevant. So I'm curious about your opinion of embedding highly localized simple logical operators amongst the core memory circuitry itself. I've heard a slight amount about work in this direction, and it seems fascinating -- instead of requesting the raw contents of a block of memory, request the contents run through a highly local but massively parallelizable operation -- bit/byte/word interleaved XOR/ADD/MUL, for example. Obviously semiconductors can do more than store and forward; do you believe we a) will and b) should see memory implement trivial operations directly? What about non-turing complete instruction sets?
Yours Truly,
Dan Kaminsky
DoxPara Research
http://www.doxpara.com
P.S. Please forgive me if this entire post reads like "What about a beowulf cluster of DIMMs?" P.P.S. Be honest: Do you ever find it ironic that the Internet Gold Standard for Ethernet cards ended up being called Tulip?
The story of Solomon points out that there are indeed discrete, indivisible quantities in this world that humans deal with on a regular basis. Though physically, the "type conversion" of the child into two bloody halves is possible, it's not likely what any programmer or parent wants.
All sorts of other discretes exist for programmers. How many packets can I send, given one hour? 4/10th's of a packet is not a packet sent. How many widgets can be produced? A widget almost produced can't be sold. And so on. There is reality other than floats, good sir.
You get failures once a month -- gracefully degrading failovers, no less.
For God's sake, we're talking about a site who's *leftover* traffic *itself* is a specially named effect, known for crippling chunks of the Internet on demand:-)
At some point, you have to admit -- whatever minimal DB functionality MySQL provides, it's certainly powerful to serve at least one very useful purpose -- hosting Slashdot.
--Dan
Re:Slashdot Users Are Pretty Damn Objective
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IBM, MS Critique MySQL
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· Score: 3, Funny
Amusing.
So basically what you're saying is that a bunch of people who use MySQL as the backend for a massively scalable dynamic website believe MySQL can be used as the backend for a massively scalable dynamic website. In fact, there's so sure it's possible they'll occasionally mention this belief *on* their MySQL-backended, massively scalable dynamic website.
Meanwhile, the users of this MySQL-backended, massively scalable dynamic website take every single opportunity to mention the limitations, flaws, and general lack of scalability of MySQL. They usually do this after reading through hundreds of posts that say the exact same thing, brought to them dynamically within a couple seconds of their request via the horribly limited, terribly flawed, completely unscalable database they're posting nobody should ever, ever use.:-)
Slashdot Users Are Pretty Damn Objective
on
IBM, MS Critique MySQL
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· Score: 4, Interesting
Anyone realize this?
Lotsa boosterism in the story titles themselves, but there's never, ever, ever been a Slashdot story about MySQL where 3/4ths of the population didn't basically say:
MySQL may be fast, but it's underfeatured. Postgres does rule, though!
I don't get it. Does anyone but the people doing the writeups actually think MySQL is meant for large scale terabyte databases?
One core law of computer science is that the best solution to a small problem is never the best solution to much larger problems. Actually, the physical world works in much the same way -- a human sized insect would collapse quite quickly.
It's not the law that's surprising, it's that everyone keeps repeating it as if anyone else believed otherwise...
A Linksys wireless gateway runs for about $120, on a one time expense. Lets amortize it to a year, since in a year we'll probably have some more popular wireless tech anyway. So that's $10/mo.
Speakeasy provides DSL to business locations at around $125/mo.
We're up to $135/mo.
Assume a 30 day month. That's $4.50 a day.
Will your business make an extra $4.50 a day from either new customers or old customers that stay longer? If so, put up a hub and a sign outside, and start beating the crap out of Starbucks.
Starbucks itself is an interesting case: They demanded this gigantic infrastructure to charge patrons, and now have to charge $30 a month to break even. If they hadn't built the infrastructure *to* charge $30/mo, they wouldn't *need* the infrastructure to charge $30/mo. Amusing.
Complex roaming systems aren't really so logical with data networks. It really is cheaper to provide internet access -- it's not just tariffs; fault tolerance and random latency saves engineering work and increases flexibility. The biggest gotcha for cafe wireless is people that turn the cafe into their office; even at a dollar an hour for coffee, I can't imagine a particularly social environment forming. But this is already a potential problem, and hasn't really hit too badly. If it does in some limited contexts, just kill the power plugs. Built in time limit:-)
Incidentally, it is *not* economical to use telephone service in the US for "cheap modem access", since business phone lines are metered by the minute.
But they won't be immediately unable to move, that's the thing. At the prescheduled time, the first guy will be unable to move, the next guy will rear end him, and the third guy will rear-end the second, and so on. The speed these rear-endings resolve is related to the distance between cars.
But what if all the cars started out touching? Indeed, what if all the cars were welded together?
The pulse would travel at the speed of sound through steel -- quite fast, but not infinitely so.
See the other posts about presyncing -- essentially, you aren't responding to the car in front of you; rather you *and* the car in front are responding to information delivered some time in the past.
Yes, smart cards do present an alternate solution to the key distribution problem, but as that multibillion dollar satellite tv lawsuit in Europe shows, nothing is tamperproof. (For those who don't know -- secret keys would be stored in cards that required millions of dollars of equipment to break open, but don't worry because the two competing companies would regularly fund each other's cards being broken into.)
I don't think it can be denied that certificate systems are a complete failure; however, asymmetric systems deployed with an eye for usability can actually be astonishingly interesting. SRP -- secure remote passwords -- essentially uses a password to authenticate anonymous DH. Interestingly enough, this causes the authenticating servers to have no idea what password they're authenticating, only that it works.
Sometime soon, we'll get SRP working as a centralized authentication daemon, and Kerb will finally meet its match:-)
Actually, the analogy gets really interesting if you throw in clocks. See, lets say you've got a traffic jam, and the police tell everyone "we'll have it cleared in one hour. Here's a clock, everyone GO when one hour is up."
At 59:30, everyone turns on their car.
At 59:45, everyone revs their engine.
At 60:00, everyone GOES.
Now, that pulse is going to move really, really fast, possibly discontinuously so (car 3 might jump before car 2, after car 1). Faster than reflexes will allow. Maybe even faster than light -- how?
Because the information -- when to move -- got sent an hour ago, when the cop scheduled the motion in the future. And that information moved just about as fast as the cop could move.
--Dan
P.S. Yes, I'm glossing over time distortion effects when the officer walks over, mainly because I don't want to argue basic calculus regarding the silly arguments against simultaneous action.
P.P.S. Really amusing story -- i'll look at it more later.
I thought about explaining that, figured I'd just throw it in the inevitable response.
Basically, you schedule all the cars to start driving forward some time in the future. Given sufficient distance between the cars to begin with, it isn't hard to cause the discretized speed of the pulse transfer to exceed the speed of light, even with arbitrarily drifting clocks.
I'm going to munge this pretty righteously, but it's for a good cause (explaining how the speed of light wasn't violated).
Take a bunch of cars in traffic -- stop 'em, say there's an accident. Cops go ahead, clear the accident. Open road, right? Clear to go 65.
Does the entire traffic jam disappear immediately? Nope. Each *car* may be able to go 65 now, but they have to wait for the car in front of them to go away. That takes time -- two to five seconds. There's a bit of a blurring, as people see cars three or four cars ahead start to speed up -- but just because the cars *could* go sixty five, doesn't mean they *are*.
If you were sitting above the traffic in a copter, you'd look down and see a "pulse" travel slowly back through the crowd, as slowly everyone saw the car in front speed up. Eventually the entire group would speed up to some maximum speed.
The speed of the cars forward is the group velocity (more or less).
The speed that "all clear" pulse went backwards, that's the phase velocity.
Imagine everyone was drunk -- that pulse would go back really, really slow. Imagine everybody's car had a computer, linking 'em together. The *moment* the guy in front of them moved, they'd speed up too. That pulse would go quite fast, and traffic would be rather more bearable.
Same speed limit -- same group velocity -- but phase velocity ranges from near zero to past the speed of light, depending on whether drunk drivers or synchronized computers are behind the wheel.
At no point does any care break the speed of light, though:-)
Asymmetric algorithms, by nature of their highly condensed problems(factor this number) are both vulnerable in polynomial time to an arbitrarily precise quantum computer, as Shor explains:
"Polynomial-Time Algorithms for Prime Factorization and Discrete Logarithms on a Quantum Computer" http://epubs.siam.org/sam-bin/dbq/artic le/29317
Given that all modern crypto protocols use some variant of asymmetric crypto to transmit their symmetric key, a break in the asymmetry eventually breaks the symmetry too.
That being said, I'm personally suspicious of quantum computing. Naive students learning about lossless compression algorithms inevitably believe they can apply the same algorithm multiple times, each time shrinking the data further and further. This actually works for some algorithms, for one or two runs. Eventually Shannon takes hold; the system refuses to compress below the level of entropy in the data (indeed, it starts to expand).
I suspect there's an analogous limit on the quantum scale, past which entropic capacity will prevent computation at high qubit levels. I could be wrong, and I'll be suitably impressed when the hardware shows up on my doorstep. But computationally relevant quantum logic hasn't been shown yet, and we shouldn't act like "it's only a matter of time".
It'll be something to be excited about if quantum computing proves feasible. I'd hate to see that achievement spoiled by "We've known it was possible for a decade."
Of course, I'm just being mildly cranky. I ain't a fan of quantum crypto either -- entanglement and crypto don't work too well in the same conceptual universe. A little skepticism is useful:-)
Yours Truly,
Dan Kaminsky
DoxPara Research
http://www.doxpara.com
Once again, the equivalence of instability with insecurity rears its ugly head.
What we appear to have is a claim that airplane electronics are extraordinarily open to interference from consumer devices. They are so open, that such devices may indeed accidentally trigger safety-critical failures in the operating environment.
Lets assume this is true.
Now understand, that which can be accidental does not need to be.
If one can accidentally down a plane with a gameboy, it stands to reason that one may be able to intentionally down the plane with the very same gameboy -- easier, in fact, because the attacker knows exactly which frequencies to exploit. This is...disturbing. I cannot imagine it very difficult to stow any form of consumer electronics, even with a "time delay" activation, inside of luggage or carryon.
Now, I'm not afraid of gameboys. See, I've *met* Boeing safety engineers. Hell, I've quoted em, learned a bit from em. Paranoid doesn't begin to describe them. These guys imagine everything, and implying that they didn't budget for even a miniscule amount of shielding and noise resistance...it's almost insulting.
Hell, you don't see planes crash every time the sun decides to belch out a few terajoules of flare in our direction. Not to mention the basic design of a fuselage bears some resemblance to an EM-blocking faraday cage.
Granted, it may very well be this same paranoia that allows those same engineers to say "Please, no new equipment, we couldn't test with that precise radio environment". The *world* is an unpredictable precise radio environment, and unfortunately, so now are its residents. I hate to say it, but if a plane can't survive a ringing cell phone, it ain't Nokia who's to blame.
That being said, the UWB failure are interesting: If the claim is that UWB operates below the noise floor relative to a given frequency, then the question becomes how did the collision avoidance systems even *detect* UWB transmissions, unless they themselves operate in a baseband manner?
One answer is that noise floors might be relative: A nearby transmitter emitting weakly across all frequencies might be overpowering the far away signal tranmitting on one. This is...hard to believe, but not impossible.
I suppose that's my biggest problem with the consumer electronics ban: Since it's inconceivable that planes are actually vulnerable to random noise from consumer electronics, *all* device-level concerns become suspect. That's annoying.
If somebody -- anybody -- has evidence they feel I should see, feel free to contact me here or in email.
Yours Truly,
Dan Kaminsky
DoxPara Research
http://www.doxpara.com
I actually looked into this myself some time ago. (I was doing some research on some rather brainfucked abuses of inkjet printers.) Yes, you're absolutely right that raw fluorescent ink fails pretty spectacularly over time. Not only does sunlight (with its massive UV1/UV2 dosage) bleach the fluorescent tats down to a ugly yellow stain, but it apparently becomes quite...err...itchy over time.
Not pretty.
However, some massive new work is being done with encapsulating various forms of bio-active chemicals (the bleached ink molecules are enough to spawn an itch reaction) within various types of polymer chains. Some pretty interesting stuff is being done with encapuslating approaches...a really elegant breast cancer treatment works as follows: Take a potent anti-cancer agent (poison, to be blunt) and attach it to a non-toxic, heat-sensitive polymer, such that the combination of the two remains non-toxic.
Inject the combo into the bloodstream.
Take the patient, and dip her breasts in water hot enough to separate the polymer from the toxin. Now watch as two things happen:
1) Only the breasts reach critical temperature, so only they might be exposed to the chemo, and 2) The blood vessels in the breast will expand, and those sections with the most blood vessels will receive the highest dosage of the chemo. Those sections are usually tumors.
From what I can tell, it's pretty tricky to design the polymer that is stable at 98.6F and unstable at 105F -- any hotter, and you're doing damage with the heat alone! Creating arbitrarily stable non-toxics is comparitively much easier. That's what it sounds like they're doing here -- they're taking a molecule with a useful function (fluorescence), attaching it to something that prevents it from reaching toxicity, and linking the expression of fluorescence to the level of insulin surrounding the molecule.
It is likely a useful side effect of this will be generically functional fluorescent ink, replete with quite a bit more than the 20 pages of paperwork you're used to.
Yours Truly,
Dan Kaminsky
DoxPara Research
http://www.doxpara.com
There's an interesting semantic argument to the claim that it's conceptually impossible to patent an instruction: After all, you are being told to do something, which inherently specifies that which you are being told to do.
On what grounds would 2^8 bits of data "imply" 2^6 bits of actual information?
2^4 systems don't magically degrade to black or white, after all.
Though I'm a bit rusty on the stats, I do believe the N through N^2 process matters only during calibration. Once you've established a given correspondance between inputs and outputs, further samples may share in the results of the previous calibration. I do suspect that a large standard deviation would require greater sampling levels to achieve a given level of accuracy.
Point-based rendering has shown some amazing results -- QSplat, for example, provides results in realtime that are flat out unimaginable out of traditional engines. Even higher quality output is coming out of the Surface splatting hackers.
Image based systems also seem to be yielding results -- Gondry's Star Guitar video, which showed scenes from a window of a train synchronized to music, was undeniably compelling and could simply not have been done with traditional 3D approaches. Schodel and Essa's work with Video Sprites are also quite impressive.
I don't mean to provide a litany of unusual rendering techniques for you to ponder. I bring them up because polygonal approaches have clearly yielded some incredible results, and I'm interested to know whether you think point-based and/or image-based strategies will yield similarly disruptive fruit. Also, I'm curious whether you're aware of any other particularly obscure but powerful methods for scene generation.
So, in short: What's next for 3D?
Yours Truly,
Dan Kaminsky
DoxPara Research
http://www.doxpara.com
Not particularly impressed, to be blunt. It's the mastery of sharp edges. Yay.
Don't worry, I was also not particularly impressed by the original iMac or the toilet bowl iBook.
OK, I admit some appreciation of the titanium iBook. But I agree with you wholeheartedly about Apple getting more credit than they're worth -- they do things slightly differently and get hoisted up as the bearer of all things new.
And I think you agree with me too -- the point about the $50 beige cases being exactly what I was originally posting about.
Slashdot Mirror
Of course, this is just the start of a much bigger picture, that'll see the filing system become something akin to a searchable knowledge store. Unfortunately, it's not going to happen quickly. For starters, if you were to suggest to the maintainer of app foo that they should store their data as lots of small files, they's say "no way, some of my users are on ext3, or xfs, or jfs" etc.
ReiserFS in Userspace.
--Dan
If it wasn't beneficial to existing creative entities to draw upon shared cultural history residing in the public domain, such creative entities wouldn't do so already.
As much as I don't want to accept that Mickey Mouse should enter the public domain, I can't help but notice that The Little Mermaid has a bit more to her than shellfish and a talking crab sidekick.
In my mind, the bottom line is that every dollar Disney has ever made mining the public domain is concrete proof that there's value to having one. One could make the argument that a creation as actively maintained as Mickey Mouse should be granted a special exemption -- and I might even buy that, based on the idea that there's no sense dragging 20th century creative works into obscurity (and make no mistake, that's where they'll go!) so that one work might keep its trademarkability.
But I don't think it's possible to argue the public domain is useless. If it was, Disney Wouldn't Keep Using It.
Pop Art didn't begin with Warhol.
Yours Truly,
Dan Kaminsky
DoxPara Research
http://www.doxpara.com
video games give us the feel that we are part of the action
Who's us?
See, here's how it works:
"I watch movies. Don't touch my movies. I don't play video games. Fuck video games."
It's just that simple. "I drive. I don't smoke. I skydive. I don't gamble. I drink, but not so much that I get drunk. I tend to hang out in groups of three to seven people. I enjoy sports. Whatever I do must be legal. Ban whatever I'd never do, fine by me."
Yours Truly,
Dan Kaminsky
DoxPara Research
http://www.doxpara.com
I can imagine an interesting architecture for SHM coherency involving L2 Broadcast as the backhaul and random hash broadcasts for most-recent-update-received synchronization. As long as updates are reasonably rare, this can work astonishingly well, though I must admit writes will inevitably block for significantly longer periods of time than they otherwise would locally. Fits in well with some other packet mangling I'm doing...toss me a mail, will ya?
o -the-2GB-space)
Of course, the obvious approach of only migrating processes and not the shared memory it allocated (instead using SHM-over-TCP-maybe-with-SEQ#'s-directly-mapping-t
also should work.
--Dan
www.doxpara.com
Dr. Becker,
As I'm sure you've noticed, the price of memory has been driven into the ground -- indeed, it's so inexpensive, the economics seem to have rendered the usage of virtual memory nearly obsolete. Need another 256MB? Spend the $20 and buy it. It's just that simple.
Now, memory makers can't let their goods be absolutely commodified forever, and I'm unconvinced that further speed increases, either in latency or bandwidth, will remain permanently relevant. So I'm curious about your opinion of embedding highly localized simple logical operators amongst the core memory circuitry itself. I've heard a slight amount about work in this direction, and it seems fascinating -- instead of requesting the raw contents of a block of memory, request the contents run through a highly local but massively parallelizable operation -- bit/byte/word interleaved XOR/ADD/MUL, for example. Obviously semiconductors can do more than store and forward; do you believe we a) will and b) should see memory implement trivial operations directly? What about non-turing complete instruction sets?
Yours Truly,
Dan Kaminsky
DoxPara Research
http://www.doxpara.com
P.S. Please forgive me if this entire post reads like "What about a beowulf cluster of DIMMs?"
P.P.S. Be honest: Do you ever find it ironic that the Internet Gold Standard for Ethernet cards ended up being called Tulip?
So, two parents divorce, and each gets half.
Problem is, they've only got one kid.
How much does each parent get?
The story of Solomon points out that there are indeed discrete, indivisible quantities in this world that humans deal with on a regular basis. Though physically, the "type conversion" of the child into two bloody halves is possible, it's not likely what any programmer or parent wants.
All sorts of other discretes exist for programmers. How many packets can I send, given one hour? 4/10th's of a packet is not a packet sent. How many widgets can be produced? A widget almost produced can't be sold. And so on. There is reality other than floats, good sir.
--Dan
You get failures once a month -- gracefully degrading failovers, no less.
:-)
For God's sake, we're talking about a site who's *leftover* traffic *itself* is a specially named effect, known for crippling chunks of the Internet on demand
At some point, you have to admit -- whatever minimal DB functionality MySQL provides, it's certainly powerful to serve at least one very useful purpose -- hosting Slashdot.
--Dan
Amusing.
:-)
So basically what you're saying is that a bunch of people who use MySQL as the backend for a massively scalable dynamic website believe MySQL can be used as the backend for a massively scalable dynamic website. In fact, there's so sure it's possible they'll occasionally mention this belief *on* their MySQL-backended, massively scalable dynamic website.
Meanwhile, the users of this MySQL-backended, massively scalable dynamic website take every single opportunity to mention the limitations, flaws, and general lack of scalability of MySQL. They usually do this after reading through hundreds of posts that say the exact same thing, brought to them dynamically within a couple seconds of their request via the horribly limited, terribly flawed, completely unscalable database they're posting nobody should ever, ever use.
--Dan
SSH over USPS!
--Dan
Anyone realize this?
Lotsa boosterism in the story titles themselves, but there's never, ever, ever been a Slashdot story about MySQL where 3/4ths of the population didn't basically say:
MySQL may be fast, but it's underfeatured. Postgres does rule, though!
I don't get it. Does anyone but the people doing the writeups actually think MySQL is meant for large scale terabyte databases?
One core law of computer science is that the best solution to a small problem is never the best solution to much larger problems. Actually, the physical world works in much the same way -- a human sized insect would collapse quite quickly.
It's not the law that's surprising, it's that everyone keeps repeating it as if anyone else believed otherwise...
--Dan
Lets see.
:-)
A Linksys wireless gateway runs for about $120, on a one time expense. Lets amortize it to a year, since in a year we'll probably have some more popular wireless tech anyway. So that's $10/mo.
Speakeasy provides DSL to business locations at around $125/mo.
We're up to $135/mo.
Assume a 30 day month. That's $4.50 a day.
Will your business make an extra $4.50 a day from either new customers or old customers that stay longer? If so, put up a hub and a sign outside, and start beating the crap out of Starbucks.
Starbucks itself is an interesting case: They demanded this gigantic infrastructure to charge patrons, and now have to charge $30 a month to break even. If they hadn't built the infrastructure *to* charge $30/mo, they wouldn't *need* the infrastructure to charge $30/mo. Amusing.
Complex roaming systems aren't really so logical with data networks. It really is cheaper to provide internet access -- it's not just tariffs; fault tolerance and random latency saves engineering work and increases flexibility. The biggest gotcha for cafe wireless is people that turn the cafe into their office; even at a dollar an hour for coffee, I can't imagine a particularly social environment forming. But this is already a potential problem, and hasn't really hit too badly. If it does in some limited contexts, just kill the power plugs. Built in time limit
Incidentally, it is *not* economical to use telephone service in the US for "cheap modem access", since business phone lines are metered by the minute.
--Dan
But they won't be immediately unable to move, that's the thing. At the prescheduled time, the first guy will be unable to move, the next guy will rear end him, and the third guy will rear-end the second, and so on. The speed these rear-endings resolve is related to the distance between cars.
But what if all the cars started out touching? Indeed, what if all the cars were welded together?
The pulse would travel at the speed of sound through steel -- quite fast, but not infinitely so.
--Dan
See the other posts about presyncing -- essentially, you aren't responding to the car in front of you; rather you *and* the car in front are responding to information delivered some time in the past.
--Dan
Excellent response.
:-)
Yes, smart cards do present an alternate solution to the key distribution problem, but as that multibillion dollar satellite tv lawsuit in Europe shows, nothing is tamperproof. (For those who don't know -- secret keys would be stored in cards that required millions of dollars of equipment to break open, but don't worry because the two competing companies would regularly fund each other's cards being broken into.)
I don't think it can be denied that certificate systems are a complete failure; however, asymmetric systems deployed with an eye for usability can actually be astonishingly interesting. SRP -- secure remote passwords -- essentially uses a password to authenticate anonymous DH. Interestingly enough, this causes the authenticating servers to have no idea what password they're authenticating, only that it works.
Sometime soon, we'll get SRP working as a centralized authentication daemon, and Kerb will finally meet its match
--Dan
GPS Time signals propogate at the speed of light. Using local time(synced through something like sntp) w/ prescheduling lets you avoid propogation.
--Dan
Actually, the analogy gets really interesting if you throw in clocks. See, lets say you've got a traffic jam, and the police tell everyone "we'll have it cleared in one hour. Here's a clock, everyone GO when one hour is up."
At 59:30, everyone turns on their car.
At 59:45, everyone revs their engine.
At 60:00, everyone GOES.
Now, that pulse is going to move really, really fast, possibly discontinuously so (car 3 might jump before car 2, after car 1). Faster than reflexes will allow. Maybe even faster than light -- how?
Because the information -- when to move -- got sent an hour ago, when the cop scheduled the motion in the future. And that information moved just about as fast as the cop could move.
--Dan
P.S. Yes, I'm glossing over time distortion effects when the officer walks over, mainly because I don't want to argue basic calculus regarding the silly arguments against simultaneous action.
P.P.S. Really amusing story -- i'll look at it more later.
Pi--
I thought about explaining that, figured I'd just throw it in the inevitable response.
Basically, you schedule all the cars to start driving forward some time in the future. Given sufficient distance between the cars to begin with, it isn't hard to cause the discretized speed of the pulse transfer to exceed the speed of light, even with arbitrarily drifting clocks.
--Dan
I'm going to munge this pretty righteously, but it's for a good cause (explaining how the speed of light wasn't violated).
:-)
Take a bunch of cars in traffic -- stop 'em, say there's an accident. Cops go ahead, clear the accident. Open road, right? Clear to go 65.
Does the entire traffic jam disappear immediately? Nope. Each *car* may be able to go 65 now, but they have to wait for the car in front of them to go away. That takes time -- two to five seconds. There's a bit of a blurring, as people see cars three or four cars ahead start to speed up -- but just because the cars *could* go sixty five, doesn't mean they *are*.
If you were sitting above the traffic in a copter, you'd look down and see a "pulse" travel slowly back through the crowd, as slowly everyone saw the car in front speed up. Eventually the entire group would speed up to some maximum speed.
The speed of the cars forward is the group velocity (more or less).
The speed that "all clear" pulse went backwards, that's the phase velocity.
Imagine everyone was drunk -- that pulse would go back really, really slow. Imagine everybody's car had a computer, linking 'em together. The *moment* the guy in front of them moved, they'd speed up too. That pulse would go quite fast, and traffic would be rather more bearable.
Same speed limit -- same group velocity -- but phase velocity ranges from near zero to past the speed of light, depending on whether drunk drivers or synchronized computers are behind the wheel.
At no point does any care break the speed of light, though
--Dan
Asymmetric algorithms, by nature of their highly condensed problems(factor this number) are both vulnerable in polynomial time to an arbitrarily precise quantum computer, as Shor explains:
c le/29317
:-)
"Polynomial-Time Algorithms for Prime Factorization and Discrete Logarithms on a Quantum Computer"
http://epubs.siam.org/sam-bin/dbq/arti
Given that all modern crypto protocols use some variant of asymmetric crypto to transmit their symmetric key, a break in the asymmetry eventually breaks the symmetry too.
That being said, I'm personally suspicious of quantum computing. Naive students learning about lossless compression algorithms inevitably believe they can apply the same algorithm multiple times, each time shrinking the data further and further. This actually works for some algorithms, for one or two runs. Eventually Shannon takes hold; the system refuses to compress below the level of entropy in the data (indeed, it starts to expand).
I suspect there's an analogous limit on the quantum scale, past which entropic capacity will prevent computation at high qubit levels. I could be wrong, and I'll be suitably impressed when the hardware shows up on my doorstep. But computationally relevant quantum logic hasn't been shown yet, and we shouldn't act like "it's only a matter of time".
It'll be something to be excited about if quantum computing proves feasible. I'd hate to see that achievement spoiled by "We've known it was possible for a decade."
Of course, I'm just being mildly cranky. I ain't a fan of quantum crypto either -- entanglement and crypto don't work too well in the same conceptual universe. A little skepticism is useful
Yours Truly,
Dan Kaminsky
DoxPara Research
http://www.doxpara.com
Once again, the equivalence of instability with insecurity rears its ugly head.
What we appear to have is a claim that airplane electronics are extraordinarily open to interference from consumer devices. They are so open, that such devices may indeed accidentally trigger safety-critical failures in the operating environment.
Lets assume this is true.
Now understand, that which can be accidental does not need to be.
If one can accidentally down a plane with a gameboy, it stands to reason that one may be able to intentionally down the plane with the very same gameboy -- easier, in fact, because the attacker knows exactly which frequencies to exploit. This is...disturbing. I cannot imagine it very difficult to stow any form of consumer electronics, even with a "time delay" activation, inside of luggage or carryon.
Now, I'm not afraid of gameboys. See, I've *met* Boeing safety engineers. Hell, I've quoted em, learned a bit from em. Paranoid doesn't begin to describe them. These guys imagine everything, and implying that they didn't budget for even a miniscule amount of shielding and noise resistance...it's almost insulting.
Hell, you don't see planes crash every time the sun decides to belch out a few terajoules of flare in our direction. Not to mention the basic design of a fuselage bears some resemblance to an EM-blocking faraday cage.
Granted, it may very well be this same paranoia that allows those same engineers to say "Please, no new equipment, we couldn't test with that precise radio environment". The *world* is an unpredictable precise radio environment, and unfortunately, so now are its residents. I hate to say it, but if a plane can't survive a ringing cell phone, it ain't Nokia who's to blame.
That being said, the UWB failure are interesting: If the claim is that UWB operates below the noise floor relative to a given frequency, then the question becomes how did the collision avoidance systems even *detect* UWB transmissions, unless they themselves operate in a baseband manner?
One answer is that noise floors might be relative: A nearby transmitter emitting weakly across all frequencies might be overpowering the far away signal tranmitting on one. This is...hard to believe, but not impossible.
I suppose that's my biggest problem with the consumer electronics ban: Since it's inconceivable that planes are actually vulnerable to random noise from consumer electronics, *all* device-level concerns become suspect. That's annoying.
If somebody -- anybody -- has evidence they feel I should see, feel free to contact me here or in email.
Yours Truly,
Dan Kaminsky
DoxPara Research
http://www.doxpara.com
I actually looked into this myself some time ago. (I was doing some research on some rather brainfucked abuses of inkjet printers.) Yes, you're absolutely right that raw fluorescent ink fails pretty spectacularly over time. Not only does sunlight (with its massive UV1/UV2 dosage) bleach the fluorescent tats down to a ugly yellow stain, but it apparently becomes quite...err...itchy over time.
Not pretty.
However, some massive new work is being done with encapsulating various forms of bio-active chemicals (the bleached ink molecules are enough to spawn an itch reaction) within various types of polymer chains. Some pretty interesting stuff is being done with encapuslating approaches...a really elegant breast cancer treatment works as follows: Take a potent anti-cancer agent (poison, to be blunt) and attach it to a non-toxic, heat-sensitive polymer, such that the combination of the two remains non-toxic.
Inject the combo into the bloodstream.
Take the patient, and dip her breasts in water hot enough to separate the polymer from the toxin. Now watch as two things happen:
1) Only the breasts reach critical temperature, so only they might be exposed to the chemo, and
2) The blood vessels in the breast will expand, and those sections with the most blood vessels will receive the highest dosage of the chemo. Those sections are usually tumors.
From what I can tell, it's pretty tricky to design the polymer that is stable at 98.6F and unstable at 105F -- any hotter, and you're doing damage with the heat alone! Creating arbitrarily stable non-toxics is comparitively much easier. That's what it sounds like they're doing here -- they're taking a molecule with a useful function (fluorescence), attaching it to something that prevents it from reaching toxicity, and linking the expression of fluorescence to the level of insulin surrounding the molecule.
It is likely a useful side effect of this will be generically functional fluorescent ink, replete with quite a bit more than the 20 pages of paperwork you're used to.
Yours Truly,
Dan Kaminsky
DoxPara Research
http://www.doxpara.com
There's an interesting semantic argument to the claim that it's conceptually impossible to patent an instruction: After all, you are being told to do something, which inherently specifies that which you are being told to do.
Wrap your mind around that for a second.
--Dan
Perciva--
On what grounds would 2^8 bits of data "imply" 2^6 bits of actual information?
2^4 systems don't magically degrade to black or white, after all.
Though I'm a bit rusty on the stats, I do believe the N through N^2 process matters only during calibration. Once you've established a given correspondance between inputs and outputs, further samples may share in the results of the previous calibration. I do suspect that a large standard deviation would require greater sampling levels to achieve a given level of accuracy.
--Dan
Point-based rendering has shown some amazing results -- QSplat, for example, provides results in realtime that are flat out unimaginable out of traditional engines. Even higher quality output is coming out of the Surface splatting hackers.
Image based systems also seem to be yielding results -- Gondry's Star Guitar video, which showed scenes from a window of a train synchronized to music, was undeniably compelling and could simply not have been done with traditional 3D approaches. Schodel and Essa's work with Video Sprites are also quite impressive.
I don't mean to provide a litany of unusual rendering techniques for you to ponder. I bring them up because polygonal approaches have clearly yielded some incredible results, and I'm interested to know whether you think point-based and/or image-based strategies will yield similarly disruptive fruit. Also, I'm curious whether you're aware of any other particularly obscure but powerful methods for scene generation.
So, in short: What's next for 3D?
Yours Truly,
Dan Kaminsky
DoxPara Research
http://www.doxpara.com
AC--
Hadn't seen the NetVista before.
Not particularly impressed, to be blunt. It's the mastery of sharp edges. Yay.
Don't worry, I was also not particularly impressed by the original iMac or the toilet bowl iBook.
OK, I admit some appreciation of the titanium iBook. But I agree with you wholeheartedly about Apple getting more credit than they're worth -- they do things slightly differently and get hoisted up as the bearer of all things new.
And I think you agree with me too -- the point about the $50 beige cases being exactly what I was originally posting about.
--Dan