What about the perfectly reflexive sail? Having two such sails poiting against each other, the ping pong of the light particles would cause acceleration for both sides.. but who, to the hell, will pay for it?
The bouncing photons would progressively redshift, their frequency approaching zero until their wavelengths became large enough to escape from between the mirrors. At that point, all the lost photon energy would have been converted to kinetic energy in the sails (and some heat, if the sails are not perfect reflectors).
I was thinking about how a radiometer works to measure thermal energy. Is this the same property that pushes the sails?
You are asking a textbook question:-)
No, the radiometer works in a different way. Notice in the radiometer that the rotation is clockwise when the black "sail" is exposed on the LEFT. If this were due to light pressure, the pressure would be greater on the RIGHT (reflective) sail and the radiometer would be spinning in the opposite direction.
What happens in the radiometer is the black sail heats up because it absorbs radiant energy. The gas around the sail (the glass bulb is very low pressure but not a perfect vacuum) conducts heat away from the sail, heating and expanding in the process. The expanding gas reacts against the sail, pushing it away.
If the radiometer bulb was evacuated to a perfect vacuum, the radiometer would actually spin the opposite direction because the light pressure effect would dominate.
The only way the incoming particle's p can be exactly reversed is in the limiting case of infinite mass of the resting mass.
I was trying to leave out the complications. The photon is redshifted after reflection. The frequency it redshifts to is the one which is consistent with conservation of both momentum and energy.
A perfectly non-reflective surface (i.e. a black surface) would experience half the force that a perfectly reflective surface would. In other words, a black sail will work, but only half as well as a mirrored sail would work.
This is due to conservation of momentum. If a photon is reflected, its momentum p is reversed to be -p. Thus the sail must acquire a momentum 2p to conserve momentum. Whereas if the photon is absorbed, its momentum changes from p to 0, thus the momentum of the sail must increase by p, again to preserve momentum.
The difference in kinetic energy is converted into heat. A black sail heats up. An ideal, perfectly reflective mirrored sail does not heat up at all.
And we all know that Microsoft's software is malicious...
Sure, we know that code coming from Microsoft tends to be honest. But that doesn't preclude the possibility of somebody inside MS having a bad day and putting a trojan into SP3, or something like that. Very unlikely, but possible.
But that wasn't even the point of the thread. The point was using digital signatures to make it "safe" to exchange files over P2P, and I was pointing out that, in that context, digital signatures are no silver bullet.
If you aren't Microsoft then it won't be signed by Microsoft and odds are I won't download it because it doesn't say Microsoft. Isn't that the point?
No, the point is to avoid installing malicious software. I am not interested in the signature from the standpoint of, "Is this person who he says he is," I am interested in knowing, "Is this software what I think it is."
Not to mention the problems with running a CA are great. First, what information do you require? Driver's license? SSN? Mother's maiden name? How do you verify identity without intruding on privacy? Remember, this is supposed to be a CA for geeks, a temple of wisdom and fairness, etc etc etc. People will go apeshit if you start asking for personal information, but if you don't have personal information the signature doesn't mean dick.
What I'm interested in, when I download something off P2P or elsewhere, is that the software is what I think it is. I do not care if the author is who he says he is, if it comes from where it says it comes from, etc. I care that it does what it says it should do.
We must find a way to certify code, not identities. Unfortunately, there is no magic algorithm which can look at an executable program and tell whether or not it will do something malicious. Until such a thing is invented (which is probably never) we'll have to settle for certifying identities, which is only marginally related to preventing malicious code.
The images and videos are copyrighted by their respective owners. There's no legal difference between slinging porn videos and giant Hollywood movies, except that in the latter case you are orders of magnitude more likely to be prosecuted.
For some reason, porno authors aren't very interested in enforcing copyright on their works, but they certainly do hold the copyrights. And you are, technically, breaking the law by sharing porn.
The authentication would rely on the Public Key Infrastructure and have chains of trust that would go back to the CA's, just like we do with SSL certs.
You mean we should shell out more money to Verisign?
This still doesn't eliminate the possibility of malicious use. It isn't exactly difficult to get a certified digital ID. Suppose I get one and use it to sign a trojan horse that's time bombed to go off in six months? That's plenty of time to spread. Once the logic bomb goes off, sure, my ID will be listed on the CRL and revoked, but I still did massive damage, and I can just go acquire a new certified ID and start over again.
Signatures prove that you are who you say you are. They don't prove that you aren't going to do something malicious!
The guy is the head of the recording head department? What other industry do they expect him to find employment in?
Nanoelectronics? Precision circuit design? Surface analysis? Micromachining? There are a ton of possibilities.
If you specialize yourself to the point of having nowhere else to go and no useful skillset outside of your current position, I think you've made a serious life mistake... This guy is surely smart enough to find other ways to apply his knowledge.
put these devices and systems behind something as simple as a $50 hardware NAT firewall, especially for a device that costs hundreds of thousands - or millions - of dollars?
How is a firewall going to stop an insider from exploiting the network? Does working in a hospital magically transform a person into a paragon of morality?
If your data is important to you, back it up somewhere. If it is sensitive, encrypt it.
If you want to be reimbursed for your laptop if it is stolen, buy an insurance policy to cover it.
Yes, it might cost a bit more than a "good" lock, but not a lot more (my girlfriend insured her PowerBook for two years for $90), and you're guaranteed to get your laptop back if it is stolen. Or if it burns in a fire -- let's see your Kensington warranty cover that. Just make sure your policy gives you "replacement cost," not just "market value." And back up your friggin' data!
Reading the decription of the technology it really sounds like a polarising filter for radio frequencies:
The description talks about copper crosses. If it was a polarizing filter it would have copper wires along one axis only.
However, although it's not a filter, its operation is clearly based somehow on the polarization of the wave -- it's the only explanation I can think of why they would have a network of slits at 45 degrees to the crosses. My best guess is that certain frequencies (e.g., mobile phone frequencies) interact with the copper crosses and become polarized strongly in one direction, and are allows to exit the slits on the backside. All other frequencies are not as strongly polarized and therefore are absorbed on the backside.
One time, we found a phone number that apparently patched through to the PA system in a warehouse somewhere. No menu or anything, you simply called this number and your voice was broadcast throughout some warehouse somewhere. You could also hear what was going on in the warehouse.
In our own solar system, most of the planets have a very circular orbit, and thus the Sun doesn't wobble as much.
The amount of wobble has nothing to do with the degree of circularity of the orbit. Our Sun wobbles quite a bit, in fact. The gravity of Jupiter causes the center of the Sun to move in a circle with a diameter of approximately 1 million miles. That's more than 1 part in 100 of the distance between the Earth and the Sun -- easily detectable.
I think it is time we started attributing vulnerabilities to the authors (just as we do with companies).
Terrible idea.
I can tell you right now, if I knew I'd be held personally responsible for bugs in open source software I contributed to, I would not contribute. If you want me to take responsibility for my bugs, give me money.
If you don't like buggy free software, don't use it. What you're describing sounds almost like an inverse meritocracy, where people get branded if they don't write code that's "good enough." All that serves to do is scare people away from contributing.
What's really irritating to me, is that often times the people bitching the loudest are unwilling and unable to contribute to such projects themselves. Sorry, but I'm not going to subject myself to a bunch of amateur sideline criticism. It ain't worth it.
Letters per second isn't really as good a measure (I think) because it doesn't exclude "unfair" combinations.
For example, I can type pokerpokerpokerpokerpokerpokerpokerpokerpokerpoker poker at probably around 10 letters per second, but that's a contrived test.
And "quantity of information" is more closely tied to the number of words, not the number of letters. Therefore, words per minute is probably a better measure of how much information you can type in a given period of time, instead of merely measuring how fast your fingers can bang on the keys.
BOTH. Teach kids how to type in 6th grade with a 1 semester course.
Are you SERIOUS? Typing classes are obsolete. With the internet and home computers as pervasive as they are, kids are almost universally exposed to computers at a very young age.
It would be like having a class on "How to dial a phone." Pointless.
Many people are saying "If he didn't like the terms of the contract, he shouldn't have agreed to it."
That's all well and good, but what if every employer has such terms? Where do you turn for employment without being subjected to this garbage?
Claiming ownership of employee ideas developed in their off time is simply wrong. We are people, not "assets" or "resources." Is this legal? Probably. But I'm sure most people will agree that what is legal is not always ethical.
On the other hand, since these chips use inductance to generate radio waves for the purpose of communication, couldn't a lesser amount of electromagnetic radiation possibly induce spurious signals?
I see the source of the misunderstanding. There are two kinds of inductance: electrical and magnetic. We're talking electrical inductance here. Quite simply, charge builds up on one plate and physically repels the charges from the other plate.
This has nothing to do with radio waves. To produce a wave you need an antenna, and capacitor plates are about as far from antennas as you can get.
In order to interfere with this system you would have to either hit it with very intense radiation -- and any such radiation would have a similar jamming effect on a traditional system with wires -- or, you would have to somehow introduce an interfering electric field into the region between the capacitor plates, which is nearly impossible to do without getting extremely close to the device.
It will be susceptible to jamming, but to no higher degree than any other system is susceptible.
Slashdot Mirror
The bouncing photons would progressively redshift, their frequency approaching zero until their wavelengths became large enough to escape from between the mirrors. At that point, all the lost photon energy would have been converted to kinetic energy in the sails (and some heat, if the sails are not perfect reflectors).
You are asking a textbook question :-)
No, the radiometer works in a different way. Notice in the radiometer that the rotation is clockwise when the black "sail" is exposed on the LEFT. If this were due to light pressure, the pressure would be greater on the RIGHT (reflective) sail and the radiometer would be spinning in the opposite direction.
What happens in the radiometer is the black sail heats up because it absorbs radiant energy. The gas around the sail (the glass bulb is very low pressure but not a perfect vacuum) conducts heat away from the sail, heating and expanding in the process. The expanding gas reacts against the sail, pushing it away.
If the radiometer bulb was evacuated to a perfect vacuum, the radiometer would actually spin the opposite direction because the light pressure effect would dominate.
I was trying to leave out the complications. The photon is redshifted after reflection. The frequency it redshifts to is the one which is consistent with conservation of both momentum and energy.
A perfectly non-reflective surface (i.e. a black surface) would experience half the force that a perfectly reflective surface would. In other words, a black sail will work, but only half as well as a mirrored sail would work.
This is due to conservation of momentum. If a photon is reflected, its momentum p is reversed to be -p. Thus the sail must acquire a momentum 2p to conserve momentum. Whereas if the photon is absorbed, its momentum changes from p to 0, thus the momentum of the sail must increase by p, again to preserve momentum.
The difference in kinetic energy is converted into heat. A black sail heats up. An ideal, perfectly reflective mirrored sail does not heat up at all.
Sure, we know that code coming from Microsoft tends to be honest. But that doesn't preclude the possibility of somebody inside MS having a bad day and putting a trojan into SP3, or something like that. Very unlikely, but possible.
But that wasn't even the point of the thread. The point was using digital signatures to make it "safe" to exchange files over P2P, and I was pointing out that, in that context, digital signatures are no silver bullet.
No, the point is to avoid installing malicious software. I am not interested in the signature from the standpoint of, "Is this person who he says he is," I am interested in knowing, "Is this software what I think it is."
Not to mention the problems with running a CA are great. First, what information do you require? Driver's license? SSN? Mother's maiden name? How do you verify identity without intruding on privacy? Remember, this is supposed to be a CA for geeks, a temple of wisdom and fairness, etc etc etc. People will go apeshit if you start asking for personal information, but if you don't have personal information the signature doesn't mean dick.
What I'm interested in, when I download something off P2P or elsewhere, is that the software is what I think it is. I do not care if the author is who he says he is, if it comes from where it says it comes from, etc. I care that it does what it says it should do.
We must find a way to certify code, not identities. Unfortunately, there is no magic algorithm which can look at an executable program and tell whether or not it will do something malicious. Until such a thing is invented (which is probably never) we'll have to settle for certifying identities, which is only marginally related to preventing malicious code.
The images and videos are copyrighted by their respective owners. There's no legal difference between slinging porn videos and giant Hollywood movies, except that in the latter case you are orders of magnitude more likely to be prosecuted.
For some reason, porno authors aren't very interested in enforcing copyright on their works, but they certainly do hold the copyrights. And you are, technically, breaking the law by sharing porn.
Sounds like they need to use BitTorrent to distribute the .torrent file...
You mean we should shell out more money to Verisign?
This still doesn't eliminate the possibility of malicious use. It isn't exactly difficult to get a certified digital ID. Suppose I get one and use it to sign a trojan horse that's time bombed to go off in six months? That's plenty of time to spread. Once the logic bomb goes off, sure, my ID will be listed on the CRL and revoked, but I still did massive damage, and I can just go acquire a new certified ID and start over again.
Signatures prove that you are who you say you are. They don't prove that you aren't going to do something malicious!
Nanoelectronics? Precision circuit design? Surface analysis? Micromachining? There are a ton of possibilities.
If you specialize yourself to the point of having nowhere else to go and no useful skillset outside of your current position, I think you've made a serious life mistake... This guy is surely smart enough to find other ways to apply his knowledge.
How is a firewall going to stop an insider from exploiting the network? Does working in a hospital magically transform a person into a paragon of morality?
If you want to be reimbursed for your laptop if it is stolen, buy an insurance policy to cover it.
Yes, it might cost a bit more than a "good" lock, but not a lot more (my girlfriend insured her PowerBook for two years for $90), and you're guaranteed to get your laptop back if it is stolen. Or if it burns in a fire -- let's see your Kensington warranty cover that. Just make sure your policy gives you "replacement cost," not just "market value." And back up your friggin' data!
Seriously, why bother with a lock?
The description talks about copper crosses. If it was a polarizing filter it would have copper wires along one axis only.
However, although it's not a filter, its operation is clearly based somehow on the polarization of the wave -- it's the only explanation I can think of why they would have a network of slits at 45 degrees to the crosses. My best guess is that certain frequencies (e.g., mobile phone frequencies) interact with the copper crosses and become polarized strongly in one direction, and are allows to exit the slits on the backside. All other frequencies are not as strongly polarized and therefore are absorbed on the backside.
That's just a wild guess.
You mean Toneloc? Good times, good times... :-)
One time, we found a phone number that apparently patched through to the PA system in a warehouse somewhere. No menu or anything, you simply called this number and your voice was broadcast throughout some warehouse somewhere. You could also hear what was going on in the warehouse.
If the enemy is firing radar-seeking missiles at you, the first thing you do is turn the radar off. At that point it doesn't matter much, does it?
You'd only put the shield up if you were under attack.
The amount of wobble has nothing to do with the degree of circularity of the orbit. Our Sun wobbles quite a bit, in fact. The gravity of Jupiter causes the center of the Sun to move in a circle with a diameter of approximately 1 million miles. That's more than 1 part in 100 of the distance between the Earth and the Sun -- easily detectable.
Terrible idea. I can tell you right now, if I knew I'd be held personally responsible for bugs in open source software I contributed to, I would not contribute. If you want me to take responsibility for my bugs, give me money.
If you don't like buggy free software, don't use it. What you're describing sounds almost like an inverse meritocracy, where people get branded if they don't write code that's "good enough." All that serves to do is scare people away from contributing.
What's really irritating to me, is that often times the people bitching the loudest are unwilling and unable to contribute to such projects themselves. Sorry, but I'm not going to subject myself to a bunch of amateur sideline criticism. It ain't worth it.
What else exactly do you think Linux is?
Yeah, I realized I wasn't being clear enough after I posted that. I meant words per minute as measured while typing meaningful information.
Or are you saying the government should not be able to collect evidence in criminal investigations, even with a warrant?
For example, I can type pokerpokerpokerpokerpokerpokerpokerpokerpokerpoker poker at probably around 10 letters per second, but that's a contrived test.
And "quantity of information" is more closely tied to the number of words, not the number of letters. Therefore, words per minute is probably a better measure of how much information you can type in a given period of time, instead of merely measuring how fast your fingers can bang on the keys.
Are you SERIOUS? Typing classes are obsolete. With the internet and home computers as pervasive as they are, kids are almost universally exposed to computers at a very young age.
It would be like having a class on "How to dial a phone." Pointless.
This is like walking up to John Carmack and saying "Fuck you! And by the way, you write awesome games!"
Why? I can remotely understand if your a broke teenager, but employed adults have no excuse whatsoever to not buy the game.
That's all well and good, but what if every employer has such terms? Where do you turn for employment without being subjected to this garbage?
Claiming ownership of employee ideas developed in their off time is simply wrong. We are people, not "assets" or "resources." Is this legal? Probably. But I'm sure most people will agree that what is legal is not always ethical.
These slavery clauses should be banned.
I see the source of the misunderstanding. There are two kinds of inductance: electrical and magnetic. We're talking electrical inductance here. Quite simply, charge builds up on one plate and physically repels the charges from the other plate.
This has nothing to do with radio waves. To produce a wave you need an antenna, and capacitor plates are about as far from antennas as you can get.
In order to interfere with this system you would have to either hit it with very intense radiation -- and any such radiation would have a similar jamming effect on a traditional system with wires -- or, you would have to somehow introduce an interfering electric field into the region between the capacitor plates, which is nearly impossible to do without getting extremely close to the device.
It will be susceptible to jamming, but to no higher degree than any other system is susceptible.