Thrust is the derivative of momentum with respect to time, and momentum is conserved, so in an open-loop drive F=dp/dt=d/dt(E/c)=(1/c)dE/dt, so power (dE/dt) is force times C.
But here's where the novel part comes in. Every photon is bounced back and forth thousands of times between the spacecraft and a mirror. The mirror experiences the same force as the spacecraft but in the opposite direction. The spacecraft's momentum comes from "pushing against" the mirror, rather than "pushing against" the exhaust photons.
For every photon with momentum E/c, the spacecraft gets a momentum kick of E/c when it emits the photon, 2E/c when the photon bounces off it again after a round trip to the mirror, 2E/c again on the next round trip, and so on until the limits of the optics lose the photon out into space. If the drive could really deliver the thousands of photon reuses Dr. Bae talks about, then the power requirements drop to more like 1E10 watts.
OK, fitting that into ten metric tons means we still need antimatter.
>what about Flash memory blocks: is it even possible to restore, even theoretically, previous state there. Since the Flash chip interface only reports the last recorded value, and you can't really read the Flash chip in any other way except the standard interface on the chip, I'd say no.
Ross Anderson's group at Cambridge has done some interesting work on this. If a cell is stuck between a 0 and a 1, all you need to do to read the hidden value is to drop the power supply voltage. Conceptually, if the old value was 0 and you wrote a 1 and got an analog value of 0.6, then you could lower the voltage enough that it would read as 0.4, which would round to 0 and show you the old value.
If memory serves they found that erasure did less to change the physical value of a bit than overwriting did.
If it's like everything else in that space it generates a secure hash of the source material as it's being acquired. Write that down and store it someplace, and you can prove later that the data haven't changed, barring a mathematical breakthrough or the most amazing coincidence in world history.
I'd enjoy seeing (recent!) references on this, since hard drive technology has moved quite a bit since the Gutmann paper (the epilogue to which says "with the ever-increasing data density on disk platters and a corresponding reduction in feature size and use of exotic techniques to record data on the medium, it's unlikely that anything can be recovered from any recent drive except perhaps a single level via basic error-cancelling techniques").
The two best arguments I've seen among the speculation are
AGAINST: if it were possible to read under 12 layers of overwriting, wouldn't the drive manufacturers boost density by writing the same spot 12 times? FOR: a read head in a lab doesn't have to be light, may not need to be fast, and definitely doesn't have to cost less than a good dinner. In other words, it's not subject to the limitations of the drive's read head.
The actual site for the Trecorder doesn't make any claims about making a copy of RAM, that seems to have appeared in the article by spontaneous generation.
If it doesn't involve cracking the disk's case open in a cleanroom (and this is just a hot PC with write blockers), then it's at the mercy of the drive's read head and every bit it gets will be what the drive natively believes is a bit.
Recovering overwritten information isn't the big deal in forensics, anyway. Organizing, managing and documenting the mountain of evidence is. If you're dealing with well written malware, worry that it's not on the disk at all and is strictly RAM-resident.
The undamaged plant next to it was shut down as a precaution. The power the two plants generated was replaced by burning coal. Using the Office of Technology Assessment figures for premature deaths from coal burning, the accident itself killed 50 people every year from air pollution and coal mining, another 50 per year from the shutdown of the other reactor.
Coal has gotten cleaner over time, so you can't just multiply by the number of years since the accident, but it's still many hundreds of people dead.
NASA does it all the time for deep space probes, Halley's Comet returns are predicted many orbits in advance, and in general celestial mechanics is one of the most exact predictive disciplines. Even tiny deviations, such as those of Mercury's orbit (56 arc seconds per year!), are considered grounds for revising theories of gravity.
Having worked on relevant software, I can confirm that just the unclassified side of arming a cruise missile warhead involves multiple steps, some of which only happen after launch. For example, the onboard computer waits for a characteristic maneuver to happen before it goes to the next step in the arming process.
"Live" is not the word I'd use, except maybe as opposed to "dummy". The scary issue, as pointed out elsewhere, is that the inventory tracking broke down.
The "52" in "B-52" is the year the first one got built. There have been many, many upgrades since then so it's arguably fair to say "several generations", but at their base their design is only seven years newer than World War II.
Christian scripture has a very simple touchstone for recognizing dangerous religious leaders. Matthew 7:15-16 says "Watch out for false prophets. They come to you in sheep's clothing, but inwardly they are ferocious wolves. By their fruit you will recognize them. Do people pick grapes from thornbushes, or figs from thistles?"
In other words, what results emerge from their teachings? Are their followers ennobled, or are they terrorized? Are they good neighbors, or do they try to take over the neighborhood?
The American Family Association had a longer checklist with warning signs like unaccountable leadership, feelings of elitism, attempts to cut members's ties with family and friends, and rationalization of unethical conduct toward outsiders.
That would be good, but it would only help against the threat of someone eavesdropping on your phone calls. The article was about something scarier, namely turning your phone into a room bug transmitting audio to the attacker while the phone looks like it's not in use.
DNA is the active ingredient of the vaccine, if they mean what people usually mean by "DNA vaccine".
To vaccinate against a pathogen, you'd take some gene from it that codes for a surface protein, inject that DNA into muscle cells, let them express it and produce the protein, and the immune system would learn to react.
Which leaves plenty of confusion, since the goal of MS therapy would be to turn off the immune response to myelin, not to create an immune response.
The cuts in the key are individually angled so they rotate the tumblers as well as lifting them. Slots in the tumblers are lined up by the rotation to unlock a sidebar that fits into a longitudinal slot in the cylinder.
Bump keys can't even get started opening that.
More burglars have feet than have lockpicking skills. Step one in physical security is to combat kick-in attacks. Replace your strike plate, which I can almost guarantee is inadequate, with a reinforced model like the Mag-3 and most important, install it with #10 wood screws at least 3" long, so it can't tear out of the studs when subjected to a good kick. Predrill the holes and put soap on the threads so you don't break screws as you install it.
A block watch is a great idea too. Neighbors are a security mechanism.
An alarm system also protects you against fire, which depending on where you live can be a bigger threat than burglary.
Slashdot Mirror
Be careful what you wish for.
You might get it.
Thrust is the derivative of momentum with respect to time, and momentum is conserved, so in an open-loop drive F=dp/dt=d/dt(E/c)=(1/c)dE/dt, so power (dE/dt) is force times C.
But here's where the novel part comes in. Every photon is bounced back and forth thousands of times between the spacecraft and a mirror. The mirror experiences the same force as the spacecraft but in the opposite direction. The spacecraft's momentum comes from "pushing against" the mirror, rather than "pushing against" the exhaust photons.
For every photon with momentum E/c, the spacecraft gets a momentum kick of E/c when it emits the photon, 2E/c when the photon bounces off it again after a round trip to the mirror, 2E/c again on the next round trip, and so on until the limits of the optics lose the photon out into space. If the drive could really deliver the thousands of photon reuses Dr. Bae talks about, then the power requirements drop to more like 1E10 watts.
OK, fitting that into ten metric tons means we still need antimatter.
Citations:
Spying on Quakers in an "anti-terrorist" program, http://www.csmonitor.com/2005/1215/dailyUpdate.html
Teacher arrested for holding up a sign, http://www.woi-tv.com/global/story.asp?s=3276385&ClientType=Printable
I've wondered sometimes why people didn't build silicon carbide chips and put them into Venus landers.
>what about Flash memory blocks: is it even possible to restore, even theoretically, previous state there. Since the Flash chip interface only reports the last recorded value, and you can't really read the Flash chip in any other way except the standard interface on the chip, I'd say no.
Ross Anderson's group at Cambridge has done some interesting work on this. If a cell is stuck between a 0 and a 1, all you need to do to read the hidden value is to drop the power supply voltage. Conceptually, if the old value was 0 and you wrote a 1 and got an analog value of 0.6, then you could lower the voltage enough that it would read as 0.4, which would round to 0 and show you the old value.
If memory serves they found that erasure did less to change the physical value of a bit than overwriting did.
Security is fun.
That was Joanna Rutkowska herself:t kowska-ppt.pdf
http://i.i.com.com/cnwk.1d/i/z/200701/bh-dc-07-Ru
Google "Rutkowska DMA" for more discussion (one of my blogs is the third hit).
If it's like everything else in that space it generates a secure hash of the source material as it's being acquired. Write that down and store it someplace, and you can prove later that the data haven't changed, barring a mathematical breakthrough or the most amazing coincidence in world history.
I'd enjoy seeing (recent!) references on this, since hard drive technology has moved quite a bit since the Gutmann paper (the epilogue to which says "with the ever-increasing data density on disk platters and a corresponding reduction in feature size and use of exotic techniques to record data on the medium, it's unlikely that anything can be recovered from any recent drive except perhaps a single level via basic error-cancelling techniques").
The two best arguments I've seen among the speculation are
AGAINST: if it were possible to read under 12 layers of overwriting, wouldn't the drive manufacturers boost density by writing the same spot 12 times?
FOR: a read head in a lab doesn't have to be light, may not need to be fast, and definitely doesn't have to cost less than a good dinner. In other words, it's not subject to the limitations of the drive's read head.
The actual site for the Trecorder doesn't make any claims about making a copy of RAM, that seems to have appeared in the article by spontaneous generation.
But I wonder if it would be possible over a Firewire connection, given that Firewire allows direct memory access.
If it doesn't involve cracking the disk's case open in a cleanroom (and this is just a hot PC with write blockers), then it's at the mercy of the drive's read head and every bit it gets will be what the drive natively believes is a bit.
Recovering overwritten information isn't the big deal in forensics, anyway. Organizing, managing and documenting the mountain of evidence is. If you're dealing with well written malware, worry that it's not on the disk at all and is strictly RAM-resident.
You left out "introducing security vulnerabilities". Who thought it was a good idea to execute Javascript in a PDF reader?!
The undamaged plant next to it was shut down as a precaution. The power the two plants generated was replaced by burning coal. Using the Office of Technology Assessment figures for premature deaths from coal burning, the accident itself killed 50 people every year from air pollution and coal mining, another 50 per year from the shutdown of the other reactor.
Coal has gotten cleaner over time, so you can't just multiply by the number of years since the accident, but it's still many hundreds of people dead.
>We can't predict movement 10 years from now
NASA does it all the time for deep space probes, Halley's Comet returns are predicted many orbits in advance, and in general celestial mechanics is one of the most exact predictive disciplines. Even tiny deviations, such as those of Mercury's orbit (56 arc seconds per year!), are considered grounds for revising theories of gravity.
Having worked on relevant software, I can confirm that just the unclassified side of arming a cruise missile warhead involves multiple steps, some of which only happen after launch. For example, the onboard computer waits for a characteristic maneuver to happen before it goes to the next step in the arming process.
"Live" is not the word I'd use, except maybe as opposed to "dummy". The scary issue, as pointed out elsewhere, is that the inventory tracking broke down.
The "52" in "B-52" is the year the first one got built. There have been many, many upgrades since then so it's arguably fair to say "several generations", but at their base their design is only seven years newer than World War II.
Christian scripture has a very simple touchstone for recognizing dangerous religious leaders. Matthew 7:15-16 says "Watch out for false prophets. They come to you in sheep's clothing, but inwardly they are ferocious wolves. By their fruit you will recognize them. Do people pick grapes from thornbushes, or figs from thistles?"
In other words, what results emerge from their teachings? Are their followers ennobled, or are they terrorized? Are they good neighbors, or do they try to take over the neighborhood?
The American Family Association had a longer checklist with warning signs like unaccountable leadership, feelings of elitism, attempts to cut members's ties with family and friends, and rationalization of unethical conduct toward outsiders.
That's nothing compared to his quote to the effect "most of the thrust comes from the three main engines".
nmap can portscan a box without ever addressing a packet to it. Coming up with that was a true hack. (Google "idle scan").
The best place I've found to get details on news like this is the blog "Wi-Fi Networking News", by Glenn Fleishmann. http://wifinetnews.com./
Someone who hates America, or approves of how China is governed, would simply keep silent and let things go on as they have been.
That would be good, but it would only help against the threat of someone eavesdropping on your phone calls. The article was about something scarier, namely turning your phone into a room bug transmitting audio to the attacker while the phone looks like it's not in use.
The gamma ray observatories have to be in orbit. How is someone on the ground detecting gamma rays?
In the old days, a stalker had to take time off work to follow a victim and find out every place she went.
With comprehensive vehicle tracking, all he has to do is suborn someone with access to EZ-Pass records.
Too hypothetical? Then consider something that's already happened, divorce lawyers using EZ-Pass records.
Agreed, though, calling it 1984 is hyperbole as long as there are feasible alternatives to having an EZ-Pass.
http://en.wikipedia.org/wiki/DNA_vaccination
DNA is the active ingredient of the vaccine, if they mean what people usually mean by "DNA vaccine".
To vaccinate against a pathogen, you'd take some gene from it that codes for a surface protein, inject that DNA into muscle cells, let them express it and produce the protein, and the immune system would learn to react.
Which leaves plenty of confusion, since the goal of MS therapy would be to turn off the immune response to myelin, not to create an immune response.
This isn't about gene therapy.
The cuts in the key are individually angled so they rotate the tumblers as well as lifting them. Slots in the tumblers are lined up by the rotation to unlock a sidebar that fits into a longitudinal slot in the cylinder.
Bump keys can't even get started opening that.
More burglars have feet than have lockpicking skills. Step one in physical security is to combat kick-in attacks. Replace your strike plate, which I can almost guarantee is inadequate, with a reinforced model like the Mag-3 and most important, install it with #10 wood screws at least 3" long, so it can't tear out of the studs when subjected to a good kick. Predrill the holes and put soap on the threads so you don't break screws as you install it.
A block watch is a great idea too. Neighbors are a security mechanism.
An alarm system also protects you against fire, which depending on where you live can be a bigger threat than burglary.