Earth is by definition 1 A.U. from the Sun on average. Jupiter is 5.2 A.U., so by the inverse square law, sunlight is 1/27 the intensity at Jupiter. So if a 1 m^2 solar panel is sufficient in Earth orbit, you need a 27 m^2 solar panel at Jupiter. That's about 1/3 the size of the ISS solar panel. Not impossible, but difficult.
Absolutely everywhere on Earth that there is liquid water, there is life. As long as there is liquid water, life can exist in virtually any environment, deriving power from oxygen, sunlight, sulfide, nitrate, whatever. Life can exist under extreme pressure conditions, hyper-saline conditions, even radioactive conditions.
If we found liquid water on Europa and there was no life, an excellent research question would be, "why not? why is Earth special?". So either way, interesting results would be returned.
This has happened before. The Apollo 13 lunar module contained a plutonium power source for lunar surface experiments, which was intended to land on the moon and stay there. Instead, as we all know, the LM returned to Earth and burned up in the atmosphere after serving as a lifeboat for the astronauts. No major catastrophe.
OK, what density is needed? It seems like current ranges are a few hundred yards, so in metro areas your fine today because it is less than the population density and convincing more people to get involved is viable.
Well, that's a good question, actually! There are probably some results in network theory to answer it, but I can't find any immediately. As for rural populations, two issues come to mind. Firstly, reliability: what percentage of the time do you want to be guaranteed access? 99%? 99.99%? I have DSL at home, and I'm severely annoyed if it goes down for even a few minutes. Secondly, connectivity: you could be connected to your neighbors, but in an "island" that was isolated from the rest of the grid. I would suspect that both these issues would mean grassroots wireless would be a poor choice for rural populations, especially in rough terrain, where line of sight is lost. But this would be an interesting research question.
There's also the issue of latency, which would be particularly bad for the rural folks. Say each hop costs d milliseconds -- d would be nontrivial since some processing is required; each station acts like a router. Suppose each station can see a radius of a kilometer - then in the city (and suburbs), probably 10 hops or less could get anywhere, so the delay is 10d. However, if I live in podunk, and I'm calling my brother in the city, 500 km away, the delay is now 500d -- even if d=1, this is bad for voice.
I know several Ham radio guys who regularly talk to people all over the world using personally owned equipment, so this can be translated into some non-zero bandwidth.
I can't remember what the Ham bandwidth is, but it's in the low kilohertz, similar to short wave AM. Signals in this band can propagate thousands of kilometers thanks to the ionosphere. Even if the bandwidth is equal to the maximum carrier frequency (which is a large overestimate), the bandwidth is around 20 MHz. The data this could support depends on the signal-to-noise ratio (which is generally very bad in this channel), but according to one rule of thumb it might support 20 MBps (I think this is another overestimate because of the poor SNR). A voice call using the latest vocoders uses around 3 kbps, assuming full duplex and no transmission when not talking -- anything less and the quality would be terrible. So if the link were used only for vocoded voice, no data, it would support around 7000 calls simultaneously -- which is a pretty small number given the populations on either side. It gets worse, because the bandwidth can't be re-used or regenerated in any way. I think fiber or satellite backbones to cross the ocean are unavoidable.
There are some ham radio guys that privately own some pretty big towers. Could Britain talk to France via wireless if a few hundred people on each side wanted to make it happen?
Interesting. There are probably enough coastal cities of reasonable size on either side of the channel to make this practical. And Europe may be dense enough that you avoid the rural problem.
Actually, now that I think about it, I'm not so dismissive. For instance, the rural problem could be avoided by putting an 802.11 enabled router in each cell phone -- if enough people have cell phones in their cars driving down the highway, no problem. Of course, the hardware is nowhere near ready for this, and I still think it wouldn't be right for voice, and you would still need backbones. Hmm. Off to do some calculations.
Firstly, thank you for your opinion of my post above, which you characterized as (-2 YOU ARE ON CRACK). Please excuse the delay in responding; since you did not reply directly to my own post, I did not see your post immediately.
If others hadn't already done so, I would have posted a strong defense of my point, and that of the others above. To summarize, high-density peer-to-peer wireless is only tenable in a dense urban environment. It is a poor solution at best in rural areas, where the density of users is low, and is totally worthless for trans-oceanic links, which are themselves very expensive to build. As well, even with centralized agencies we have enough trouble with selfish and uncaring users hogging bandwidth. You're always relying on trust to get your packets through; without formal or contractual relationship to a provider, this would be inadequate for business.
Indeed, the only solution consistent with the article is to nationalize the infrastructure, so that equal access is enjoyed by all. In a general way, my solution to the article's question is consistent with Marxism, in which a "dictatorship of the Proletariat" first nationalizes all industries, then "melts away" into an anarchic, socialistic utopia. Of course in practice, the government doesn't go away without armed force.
Yes, it would be nice if we could do away with centralized authority and do everything through grassroots 802.11. However, that is hopelessly naive; there will always be the need for large organizations to provide at least backbone access. Now, nobody's saying that the grassroots can't provide at least some replacements to ISPs, but if it's a question of paying $40 a month to Bell for guaranteed access (and somebody to yell at if it goes out), or getting together with a bunch of freshman CS majors with wireless cards for lower-cost access, I'll take my chances with Bell. I will give the original author this, though: it's good to have the choice.
And as my own aside on the decline and fall of Slashdot, it seems that nobody can disagree with anyone else without calling them a moron, and SHOUTING. What's up with that? Do people around here feel inadequate about their own intelligence? Or is the average mental age around here 13?
Let's not forget the satellites. They're not cheap either.
And you would want a central regulatory agency to prevent jackasses (e.g., spammers) from hogging bandwidth for their own purposes.
Basically what the guy wants is nationalization of all telcos, so that your taxes pay for everything. Except everywhere that's been tried, it's been a disaster (like waiting weeks to get a phone hookup).
Fellowship of the Ring: Electrical Engineers
It's the one where Frodo and Sam write a Matlab script to simulate destroying the ring, and Gandalf wears dockers and a polo shirt with a stitched Sun Microsystems logo.
1. Accept donated computers. 2. Trade them / sell them / get rid of them for profit. 3. Use the profit to buy PCs. 4. Come up with some story about how the Macs were a disaster for their IT department, completely unusable, etc., and sell it to Microsoft for some extra cash.
Lo these many years ago, when I was in first year, pascal was used as the teaching language in many universities, including mine. It's nice enough as a sandbox language to help you learn good programming habits, yet powerful enough to do non-trivial things.
Remember the Borland EULA? It was about a paragraph long and basically said that you had to use the software "like a book", i.e., you couldn't use it in two places at the same time. That was one of the most friendly corporate EULAs I've ever seen.
Maybe my main problem is that I prefer to use laptops than desktops. Yes, the desktop hardware situation has improved markedly, but my Toshiba laptop required some severe tweaking and patching when it was new, just under a year ago. Recently I installed RH9, and it was such a disaster that I had to revert to my original RH7.3.
Forget features. I'm stuck with the vid cards that work under XFree86, in non-framebuffer mode. I still remember the day I tried to install Linux on a machine with an ATI Rage 128 card, only to have it say: sorry, driver not written yet.
SCO got sued for posting its corporate opinion of a technology matter, got sued by the people who they pissed off, and then got its web site shut down by the courts.
If it were anything other than SCO and Linux, this site would be condemning the decision and lamenting the loss of free speech rights.
I have noticed the distressing fact that people are only willing to apply the protection of free speech to the speech that they agree with.
The copyright holder will become pretty enthusiastic about it if he realises that someone else is making money from his work. This is the whole problem with submarine patents -- wait for everybody to start using it, then ask for exorbitant license fees.
Although this seems like a troll, it really isn't. In recent years, both before and after Sept. 11, the US government has passed a raft of legislation curtailing and limiting the 1st Amendment, to the general apathy of the population. Meanwhile, any suggestion of curtailing the 2nd Amendment, however mild, is met with howls of protest.
Wouldn't it be nice if the ACLU was as politically powerful as the NRA?
They used to say that no two nations that had McDonalds on their territories had ever gone to war. This supposedly meant that McDonalds was an indicator of the sophistication of the middle class, who preferred a consumerist peace to war.
Of course this changed when NATO bombed Yugoslavia.
The flaw is not in the medium, it's in the protocol. Many organizations have pointed this out. The IEEE wanted to make key distribution easy, so in a system where the administrator is not absolutely on top of everything, it's very easy to learn the key and crack the network. A point-to-point, RSA encrypted wireless link should theoretically be as difficult to crack as a wired link, if designed properly.
Is there any way to do triangulation if you have more than one base station? Then you could do some spatial security as well, by restricting access to particular zones (say, within your own building). I know the cell phone companies have been trying to implement E911 locating for a while... could you do such a thing with a carefully written 802.11 driver?
Slashdot Mirror
Earth is by definition 1 A.U. from the Sun on average. Jupiter is 5.2 A.U., so by the inverse square law, sunlight is 1/27 the intensity at Jupiter. So if a 1 m^2 solar panel is sufficient in Earth orbit, you need a 27 m^2 solar panel at Jupiter. That's about 1/3 the size of the ISS solar panel. Not impossible, but difficult.
Absolutely everywhere on Earth that there is liquid water, there is life. As long as there is liquid water, life can exist in virtually any environment, deriving power from oxygen, sunlight, sulfide, nitrate, whatever. Life can exist under extreme pressure conditions, hyper-saline conditions, even radioactive conditions.
If we found liquid water on Europa and there was no life, an excellent research question would be, "why not? why is Earth special?". So either way, interesting results would be returned.
This has happened before. The Apollo 13 lunar module contained a plutonium power source for lunar surface experiments, which was intended to land on the moon and stay there. Instead, as we all know, the LM returned to Earth and burned up in the atmosphere after serving as a lifeboat for the astronauts. No major catastrophe.
OK, what density is needed? It seems like current ranges are a few hundred yards, so in metro areas your fine today because it is less than the population density and convincing more people to get involved is viable.
Well, that's a good question, actually! There are probably some results in network theory to answer it, but I can't find any immediately. As for rural populations, two issues come to mind. Firstly, reliability: what percentage of the time do you want to be guaranteed access? 99%? 99.99%? I have DSL at home, and I'm severely annoyed if it goes down for even a few minutes. Secondly, connectivity: you could be connected to your neighbors, but in an "island" that was isolated from the rest of the grid. I would suspect that both these issues would mean grassroots wireless would be a poor choice for rural populations, especially in rough terrain, where line of sight is lost. But this would be an interesting research question.
There's also the issue of latency, which would be particularly bad for the rural folks. Say each hop costs d milliseconds -- d would be nontrivial since some processing is required; each station acts like a router. Suppose each station can see a radius of a kilometer - then in the city (and suburbs), probably 10 hops or less could get anywhere, so the delay is 10d. However, if I live in podunk, and I'm calling my brother in the city, 500 km away, the delay is now 500d -- even if d=1, this is bad for voice.
I know several Ham radio guys who regularly talk to people all over the world using personally owned equipment, so this can be translated into some non-zero bandwidth.
I can't remember what the Ham bandwidth is, but it's in the low kilohertz, similar to short wave AM. Signals in this band can propagate thousands of kilometers thanks to the ionosphere. Even if the bandwidth is equal to the maximum carrier frequency (which is a large overestimate), the bandwidth is around 20 MHz. The data this could support depends on the signal-to-noise ratio (which is generally very bad in this channel), but according to one rule of thumb it might support 20 MBps (I think this is another overestimate because of the poor SNR). A voice call using the latest vocoders uses around 3 kbps, assuming full duplex and no transmission when not talking -- anything less and the quality would be terrible. So if the link were used only for vocoded voice, no data, it would support around 7000 calls simultaneously -- which is a pretty small number given the populations on either side. It gets worse, because the bandwidth can't be re-used or regenerated in any way. I think fiber or satellite backbones to cross the ocean are unavoidable.
There are some ham radio guys that privately own some pretty big towers. Could Britain talk to France via wireless if a few hundred people on each side wanted to make it happen?
Interesting. There are probably enough coastal cities of reasonable size on either side of the channel to make this practical. And Europe may be dense enough that you avoid the rural problem.
Actually, now that I think about it, I'm not so dismissive. For instance, the rural problem could be avoided by putting an 802.11 enabled router in each cell phone -- if enough people have cell phones in their cars driving down the highway, no problem. Of course, the hardware is nowhere near ready for this, and I still think it wouldn't be right for voice, and you would still need backbones. Hmm. Off to do some calculations.
Nice, but unfortunately, Linux does not support the 286, and never has.
why not, it worked in the soviet union.
Yes, "corporate culture" was invented to take the blame for this sort of thing (e.g., Microsoft and computer security).
My good Sir or Madam,
Firstly, thank you for your opinion of my post above, which you characterized as (-2 YOU ARE ON CRACK). Please excuse the delay in responding; since you did not reply directly to my own post, I did not see your post immediately.
If others hadn't already done so, I would have posted a strong defense of my point, and that of the others above. To summarize, high-density peer-to-peer wireless is only tenable in a dense urban environment. It is a poor solution at best in rural areas, where the density of users is low, and is totally worthless for trans-oceanic links, which are themselves very expensive to build. As well, even with centralized agencies we have enough trouble with selfish and uncaring users hogging bandwidth. You're always relying on trust to get your packets through; without formal or contractual relationship to a provider, this would be inadequate for business.
Indeed, the only solution consistent with the article is to nationalize the infrastructure, so that equal access is enjoyed by all. In a general way, my solution to the article's question is consistent with Marxism, in which a "dictatorship of the Proletariat" first nationalizes all industries, then "melts away" into an anarchic, socialistic utopia. Of course in practice, the government doesn't go away without armed force.
Yes, it would be nice if we could do away with centralized authority and do everything through grassroots 802.11. However, that is hopelessly naive; there will always be the need for large organizations to provide at least backbone access. Now, nobody's saying that the grassroots can't provide at least some replacements to ISPs, but if it's a question of paying $40 a month to Bell for guaranteed access (and somebody to yell at if it goes out), or getting together with a bunch of freshman CS majors with wireless cards for lower-cost access, I'll take my chances with Bell. I will give the original author this, though: it's good to have the choice.
And as my own aside on the decline and fall of Slashdot, it seems that nobody can disagree with anyone else without calling them a moron, and SHOUTING. What's up with that? Do people around here feel inadequate about their own intelligence? Or is the average mental age around here 13?
Let's not forget the satellites. They're not cheap either. And you would want a central regulatory agency to prevent jackasses (e.g., spammers) from hogging bandwidth for their own purposes. Basically what the guy wants is nationalization of all telcos, so that your taxes pay for everything. Except everywhere that's been tried, it's been a disaster (like waiting weeks to get a phone hookup).
Fellowship of the Ring: Electrical Engineers It's the one where Frodo and Sam write a Matlab script to simulate destroying the ring, and Gandalf wears dockers and a polo shirt with a stitched Sun Microsystems logo.
Here's what they totally should have done:
1. Accept donated computers.
2. Trade them / sell them / get rid of them for profit.
3. Use the profit to buy PCs.
4. Come up with some story about how the Macs were a disaster for their IT department, completely unusable, etc., and sell it to Microsoft for some extra cash.
Somebody oughta give me an MBA.
Whatever happened to pascal?
Lo these many years ago, when I was in first year, pascal was used as the teaching language in many universities, including mine. It's nice enough as a sandbox language to help you learn good programming habits, yet powerful enough to do non-trivial things.
In fact you can download a free pascal compiler to play around with it.
Remember the Borland EULA? It was about a paragraph long and basically said that you had to use the software "like a book", i.e., you couldn't use it in two places at the same time. That was one of the most friendly corporate EULAs I've ever seen.
Maybe my main problem is that I prefer to use laptops than desktops. Yes, the desktop hardware situation has improved markedly, but my Toshiba laptop required some severe tweaking and patching when it was new, just under a year ago. Recently I installed RH9, and it was such a disaster that I had to revert to my original RH7.3.
Forget features. I'm stuck with the vid cards that work under XFree86, in non-framebuffer mode. I still remember the day I tried to install Linux on a machine with an ATI Rage 128 card, only to have it say: sorry, driver not written yet.
Look to the left -- it looks a bit like a shadow. You can also see where the foam embedded itself in a T-seal.
SCO got sued for posting its corporate opinion of a technology matter, got sued by the people who they pissed off, and then got its web site shut down by the courts.
If it were anything other than SCO and Linux, this site would be condemning the decision and lamenting the loss of free speech rights.
I have noticed the distressing fact that people are only willing to apply the protection of free speech to the speech that they agree with.
Who'll write the first sewing machine virus, which copies the contents of the pattern directory and sends it to a IRC bot in #SeW1NGH@CkOrZ
... or that takes over the machine and sews "ur sw34t3r 1s 0wnz0r3d" into whatever you're sewing.
The copyright holder will become pretty enthusiastic about it if he realises that someone else is making money from his work. This is the whole problem with submarine patents -- wait for everybody to start using it, then ask for exorbitant license fees.
Only fanboys would actualy pay for it, but there seems to be no shortage of those. Good business case.
Although this seems like a troll, it really isn't. In recent years, both before and after Sept. 11, the US government has passed a raft of legislation curtailing and limiting the 1st Amendment, to the general apathy of the population. Meanwhile, any suggestion of curtailing the 2nd Amendment, however mild, is met with howls of protest.
Wouldn't it be nice if the ACLU was as politically powerful as the NRA?
Disclaimer: I am a Canadian.
They used to say that no two nations that had McDonalds on their territories had ever gone to war. This supposedly meant that McDonalds was an indicator of the sophistication of the middle class, who preferred a consumerist peace to war.
Of course this changed when NATO bombed Yugoslavia.
I wonder what Ghandi would say about the president of India having helped design nuclear missiles?
I suspect he would have something to say about that before getting his shorts in a knot over Microsoft's EULA.
The flaw is not in the medium, it's in the protocol. Many organizations have pointed this out. The IEEE wanted to make key distribution easy, so in a system where the administrator is not absolutely on top of everything, it's very easy to learn the key and crack the network. A point-to-point, RSA encrypted wireless link should theoretically be as difficult to crack as a wired link, if designed properly.
Is there any way to do triangulation if you have more than one base station? Then you could do some spatial security as well, by restricting access to particular zones (say, within your own building). I know the cell phone companies have been trying to implement E911 locating for a while ... could you do such a thing with a carefully written 802.11 driver?