"I have doubts of you even being able to *use* a heatsink under these conditions, as the exhaust temperature will be hotter than the degradation/melting/boiling temperatures even for things like tungsten carbide and carbon."
The claim of the designer was that the surface temperature was only 1000C. I haven't checked his maths. He didn't mention using a few tricks, but he didn't elaborate.;-) Actually, come to think of it, he may have been using a special sort of piston pump; so a sort of turbopump may have been involved.
Exactly the same could be said for a continuously driven laser launcher. Both would require building batteries of lasers on a huge scale.
True. However semiconductor lasers are seriously cheap and getting cheaper all the time. If a reason for launching this much stuff can be found, then this is probably a better architecture. In particular if the lasers can scale to tourism payloads then we are talking something that can be funded.
Once you're in the upper atmosphere, losses due to drag on the way out are manageable
Pretty much be definition, if you are in the upper atmosphere you aren't in a stable orbit. And even if you leap out- your orbit still intersect the atmosphere.
Just spray gaseous fuel out to the focal point of the mirror
Sorry, doesn't work. When the fuel burns it forms an opaque combustion layer- and then your laser doesn't focus right. That architecture needs a pulsed laser.
It's a natural effect of firing a laser through something other than a vacuum. The air molecules, water molecules, and even airborne dust all absorb and/or scatter the beam.
Sure. So you need more power.
Add to that the fact that a spacecraft isn't going to go straight up into orbit, it's going to follow a slanting path that could have a laser firing through 100-200 miles of atmosphere before it even touches the spacecraft, and THEN it actually has to still have enough energy to propell the craft. This is a HUGE problem that simply cannot be gotten around by anything other than brute forcing the laser output.
Sure so add more power.
Even adaptive optics will only get you so far. The power requirements would be orders of magnitude beyond anything even on the drawing board today, and the cost would be appropriately astronomical.
Nah. Semiconductor lasers cost about $10/w right now, and dropping about 30% a day. The optics aren't, but you can get quite a few lasers per optics, so I think the lasers dominate. That means for 100 Mw you are talking about $1 billion. But this compares not unfavourably with the cost of 2 space shuttles; and the actual vehicles can have few moving parts.
Also, I have doubts about a heat-exchanger system working. Throughput tends to be low compared to the power flow required to get high ISP, and a heat exchanger means a heavier craft.
The heat exchanger is not a huge problem- the heat flow is comparable to the heat flow that a microprocessor heatsink sees in fact. And you have to compare this with turbopumps- with this system no turbopumps are needed; it's a laser powered pressure fed rocket in fact; with a high ISP.
The most practical craft design I've seen suggested, which has flown in small-scale tests, has the bottom of the craft being a curved mirror with a central projection. The laser is focused by the mirror and heats air immediately below the central projection, which is shaped to force the air to move away from the craft.
I'm not sure that's really practical as it stands. Nobody has or can afford a pulsed laser of the required power, and nobody is planning to build one. Secondly, this is purely an airbreathing design- as such it cannot make orbit (the 'orbital version' has extra tanks). Thirdly it requires a laser pointing from directly below, but 93% of achieving orbit involves sideways motion. Still, variations of these ideas may make orbit, but they are all then much more complex.
> Fuel is dirt cheap, but handling the fuel and storing the fuel and using the fuel to launch the >fuel to launch the fuel to launch the fuel is not cheap.
There's some truth to this- but for dense fuels such as kerosine/lox or kerosine/HTP the handling issues are not too great; and the higher thrust levels allow you to lose the fuel lower down, which minimises the gravity losses.
>The extra mass does not cost you fuel. The extra mass costs you PAYLOAD.
Well, if you keep the same vehicle mass but if you don't it's much more debatable; and why would different vehicle designs have the same mass? Does it cost you payload for the same price?
>1) SSTO doesn't make sense, because you have to schlep a lot of dead weight into orbit with you. >Once the fuel tank is empty, it's just drag and extra mass. Pitch it.
True if the vehicle isn't reusable. Otherwise, you a) need another tank b) you need to pay a wrench monkey to slap a new one back on c) the detach mechanism can go wrong (then what?) d) the extra mass mostly just costs you fuel- but fuel is dirt cheap compared to the tank. (The space shuttle main tank costs what? $100 million?) These may well be carbon fiber wound tanks... they aren't cheap.
>2) Reusable hasn't yet made sense, because it's almost less expensive to build a new one than to >re-certify one for flight
Yes. Although a datapoint of one (skipping over Buran, since it wasn't reused) isn't enough to draw a graph, so we don't know whether this is generally true of reusable launcher designs.
>I will point out that the payload capacity you're speaking of is about a tenth of what one Saturn V >can hurl into LEO.
Yeah. So? The cost per kg is 1/10 of the Space Shuttle. Cost per kg is a pretty reasonable metric. So you go there and back 10x and assemble on orbit.
>Ground based lasers will always be subject to thermal blooming due to atmospheric attenuation.
Interesting. Is this caused by the lasers or just natural artifacts of the atmosphere? Incidentally power is the cheap bit in the equation, and you need less of it delivered at altitude due to g-limiting anyway; so it may not matter.
> I understand the space savings advantages of kerosene, but how does the thrust produced per unit >weight compare to that of the current SRB/LRB compare?
Atleast one kerosene engine has a thrust to weight ratio of upto 130:1, and all I'm aware of are atleast 100:1. The SSMEs have a thrust to weight ratio of only 70:1. Space Shuttle loses big time;-) [In fact that's partly why you need the SRBs otherwise it couldn't physically take off- it's too heavy].
The reason is that hydrogen is seriously not very dense. So all the plumbing in the engine needs to be much bigger diameter to be able to carry the propellent flow to give the thrust. Also the tank gets huge. The extra weight is significant to the vehicle performance- you carry that engine and tank basically all the way to orbit, and it costs... This is partly offset by the greater ISP of the hydrogen, but it's at best neck and neck with hydrogen.
>Having to (hypothetically) double the fuel weight to double the thrust seems like a waste of money to me.
Fuel is irrelevant right now. Tanks and engine mass and costs are where its at. Kerosene has a lower ISP and that translates to more mass. But the greater density and the greater thrust means that the gravity losses are less (you don't carry the fuel as high before burning it) means that kerosene/LOX is excellent for a first stage. Saturn V worked this way for a reason. And if you SSTO, then you don't need hydrogen at all.
> Unfortunately given our current level of rocket > propulsion technology a single-stage-to-orbit > (SSTO) isn't terribly practical. They made some > prototypes and actually flew a scaled down > prototype in the desert, but ultimately they had >tremendous problems with the extremely high >performance rocket engine they had to use, couple >with the experimental composite cryogenic fuel >tanks.
No. This isn't the case; I was talking to some engineers that worked on the Roton just last weekend. They indicated that they knew of no problem that would have precluded the design from working. The composite cryogenic fuel tank THEY used (as opposed to the X33 debacle) - it worked fine in all testing; including something like 50 pressure cycles IRC.
>I honestly don't think we'll ever get SSTO going >with conventional chemical propellants. You simple >have to carry too much weight in fuel, which means >you need a bigger rocket, which means more fuel, >then a bigger rocket...you get the idea.
No, the simulations converge- SSTO is definitely possible. I've seen atleast 2 hard and fast designs for SSTO vehicles- the Roton and Mockingbird. The Roton would have carried 3 tonnes to LEO; the Mockingbird design didn't have a payload of any note, but was really tiny (1.5 tonnes), and cheap. I've studied both concepts extensively; they both appear workable.
The biggest argument against SSTO is that it may be more expensive. TSTO may be cheaper. Still, the argument isn't totally watertight. There's a lot of ground processing for TSTO that SSTO doesn't require and that's going to cost something. Although SSTO designs use more fuel- fuel is cheapest bit of the whole rocket by far.
>What we need is a way to extract more energy from >whatever fuel we use.
Another thing I saw on the weekend- I was at a presentation by a guy talking about a laser powered launch system. The idea is you take a large bank of lasers and point it at a hydrogen powered launch vehicle, which has a heat exchanger it uses to heat the hydrogen. The ISP is about 600 seconds, which is plenty for reaching orbit. The laser bank was priced at about $1 billion but its dropping at about 30% a year currently- only cheap semiconductor lasers are needed, and they're getting cheaper and cheaper.
Nah. Nobody clever enough to come up with the lines that he did could have really believed this stuff- it's too inventive; he'd have to have thrown too many bits away that he couldn't use. But he probably doesn't care if it's all made up- as long as it sounds right it serves his purpose...
>Legally, you can copy software all you like. You just can't distribute those copies.
Actually no. Copyright is about the right to make copies, not distribute it. And all software is by default, copyrighted by the author. Without a license to say you can copy it; you have no rights to make other copies at all, for any purpose.
In fact it has been ruled that even loading software into your computer is an act of copying it into the memory, so you can't run software without a license (legally).
A guy I work with has a PhD in image processing. He relates this story of a system that was designed to try to detect human beings, and raise the alarm so that a security guard could check it out; rather than have a security guard staring at it continuously.
Anyway, they wrote some software- it more or less just looked for a human sized blob that moved. Worked too- it could detect human beings pretty well.
Trouble was, they found that it was unreliable- it tended to think birds landing in flocks and groups were people appearing and disappearing. So they improved on the algorithm, and put in some code that if the system could see the wings flapping- it would realise it was birds and ignore it.
Anyway, it worked pretty well, so they thought they'd give a hard test. Could someone deliberately evade it? They got a grad student and told him to work out a way to fool it. They set up the computer guarding a notional prize, and set him at it.
The grad student puzzled over it for a while, then siddled into the middle of view; and removed his jacket. He then waved his jacket over his head vigorously. The computer saw all the flapping, and activated the 'bird' assignment and he was able to steal the item...
Ok, some pedantry needed here. It's not free. You've paid something for the WAP. Actually, I suspect it's fairly expensive according to some measures; but then again if you need it for your own stuff, it doesn't matter much does it?
How do you measure cost effectiveness? cost/area/achieveable bitrate might be a good metric. Wonder what the metric for cell phone masts would be. Those cells are measured in tens of miles, whereas most WAPS can do 100m or so can't they? That's 10,000x more area covered for a cell phone.
Hmm. Wonder how much a mast costs to put up; if it costs a million then it might be comparable. Interesting. Suspect a cell mast is cheaper than that though, but the WAP costs should be coming down too.
Um. Hate to break it to you. That's caused by the slow seek time, and to some extent, the CD rom standard.
Unlike a hard drive where it can get to a block in maybe 8.5ms or so; the CD needs 10s of times longer. This is particularly crucial when your OS is mounting the CD for the first time.
I think wireless is easier to deploy- no drilling, no unsightly cables, you can use your laptop on the same lan, it covers a wider area, and ad-hoc connectivity is easier.
There's nothing wrong with ethernet though. Its just more cumbersome. Potentially faster, 100 or 1000 M if you need that. But mostly, I find I don't. The only time I thought this would be useful was for a huge compile I was working on (115+ M bytes). There, not having 100M ethernet to my file server costs me about 3 minutes on a ~10 minute link; I was using 10 base T. But I don't think that's such a common thing.
>As the article mentions, the 2.4 GHz band is slowly being used for more and more transmissions. >Unless we regulate usage in some way, the wireless world will become impossible to achieve, as the >noise would be too great.
You call that noise? I call that connectivity! Why shouldn't I use them for accessing the internet? The 2.4 Ghz air waves are free; even if the backbone isn't. Why shouldn't they use me? It isn't necessarily the case that because they use my equipment, I pay for their traffic; our ISP can have them sign on through a firewall (VPN) and ensure they don't use more traffic per second than they've paid for.
If the 2.4 Ghz band is becoming used for more transmissions; that's largely a good thing. Multistandard transmitters are already appearing.
>Once you DO have such a network, however, control becomes an issue. If the network is privately >controlled, someone could be making a bundle off of everyone's usage."
I expect that it may be simply free, i.e. paid for via other means. The roads could be like that too, except the government levies a tax which is (in the UK) about 10x the amount they actually spend on the roads. Otherwise, it will be a once a year/month licence no doubt.
>If the government controlled it, it could be used for propaganda.
Yeah right. So you've grown the internet via wireless tech and suddenly the whole internet is either owned by someone OR (exclusive OR?) its all just government propaganda? Really? I don't think so...
On the contrary, the wireless node can be 100% secure (VPN software to get onto the internet + firewall that you have to log in via), so they have to log on; and you can put on traffic shaping.
Besides, bandwidth is rapidly getting cheaper and cheaper. The cost halves ever few years as the fiber optic backbones deliver lower cost per bit; DWDM, greater range and so forth; and there's a long way to go yet on that front I'd bet.
$1 to $2 per gigabyte is still pretty cheap; it's about as cheap as a CD-R. At 576k it would take me hours to download that much even maxing out the link. Even a $5 a day bill for an internet cafe does not seem outrageous if it pulls in a few more punters; it would atleast break even, and that's pretty worst case I would think.
Well, it's wireless, and you may be able to daisy chain through multiple devices (e.g. repeaters) to go longer distances. Also, this is probably a battery powered technology. Pricing depends more on how many of these devices get built, and it's potentially quite a cheap technology in fact.
Yeah, nice idea. When your first passenger idly opens the compartment and takes a secret swig whilst you pop into a 7-11 or something and then, like, DIES.
Plus, in the eyes of the law, even for thieves; killing isn't considered to good for them; it's too bad for you- you're going DOWN.
Or when the thief doesn't like whiskey and gives it to his sister...
I'm not so sure. I heard about atleast one experiment where they looked at two different universities. In one Napster use was rife. In the other it was banned. In the latter the shops around the university had a 2% reduction in sales relative to the previous year. In the one which had Napster, the sales were the same as the previous year. The music industry claimed that the fact that sales were flat proved that Napster was reducing their profits.
Ur. Come again? The yearly sales were down in the control group and stayed the same in the experimental group; therefore Napster actually increased sales by 2%! Only 2%? Still, even if that was experimental error- the experiment showed absolutely no evidence that Napster had hurt sales. None. Nada, zip zero.
I personally download a fair amount of music. If I like the music I often buy the CDs. Not EVERY time, but I'm pretty sure I buy more CDs because I listen to more music.
In a pretty real sense P2P software is self advertising for music. To some extent, to make informed decisions on what to buy, some other people DO use these technologies to rip off the distributors. But so far as I can tell, that is almost exactly balanced by the self advertising aspects. Of course the distributors are looking at this tech, and thinking "How can we screw more money out of people with this stuff", but my suspicion is that they can't.
People have a sort of built-in sense of how much money they are comfortable in spending on music, based on how music interworks with their self image. I think that's what the record companies do, they sell the image for the music.
Essentially, buying a CD is like tipping the record company and artist; and always has been really. You almost never HAVE to buy a CD in the modern world. You can tape it off the radio or TV and listen to it later. You've been able to do this for decades. Is this illegal? Yes, just barely, sometimes, or else it's just time shifting, which is actually legal. Downloading off of a computer is only a bit more convenient. People who do that often buy stacks of legitimate music too. So the record companies have done well; I don't see this changing, unless they succeed in banning music sharing. People will probably tend to spend the money on other things then, video games or whatever.
Ok, if nobody else eats all the food they bought, then is it ok if I eat it? That seems reasonable. But obviously if everyone rushes for the food when it gets laid out, the restaurant may not be able to physically lay the food out fast enough- so they have 'fight over the food' clauses.
So it's not 'all I can eat' exactly, there's a maximum I can eat because of the size of the plates they give you.
And further the restaurant doesn't in fact guarantee all you can eat in the first place; they only guarantee all I can eat upto a low limit 1/50 of the plate size; generally they'll try to fill my plate, particularly if no one else is eating, but they only guarantee 1/50 of the plate.
This being the case, I fail to see why the restaurant should impose restrictions on the food I eat; any food you want provided it isn't green! Why? "Cause I don't like it when you eat green food cos you eat more green food normally." Huh? If I'm consistently eating more than 1/50 of my plate, they're quite at liberty to limit me; within reason. However, if theres no rush on, then what do they care? The restaurant has already bought in the food from their supplier when I entered the restaurant... and for most normal people that's plenty of food. But if they decide to charge me extra 'because you're being too greedy'; tell me again who's being greedy? Why didn't you invoke my 1/50 limit then?
Slashdot Mirror
"dropping about 30% a day" - better make that 30% a year... ;-)
The claim of the designer was that the surface temperature was only 1000C. I haven't checked his maths. He didn't mention using a few tricks, but he didn't elaborate. ;-) Actually, come to think of it, he may have been using a special sort of piston pump; so a sort of turbopump may have been involved.
Exactly the same could be said for a continuously driven laser launcher. Both would require building batteries of lasers on a huge scale.
True. However semiconductor lasers are seriously cheap and getting cheaper all the time. If a reason for launching this much stuff can be found, then this is probably a better architecture. In particular if the lasers can scale to tourism payloads then we are talking something that can be funded.
Once you're in the upper atmosphere, losses due to drag on the way out are manageable
Pretty much be definition, if you are in the upper atmosphere you aren't in a stable orbit. And even if you leap out- your orbit still intersect the atmosphere.
Just spray gaseous fuel out to the focal point of the mirror
Sorry, doesn't work. When the fuel burns it forms an opaque combustion layer- and then your laser doesn't focus right. That architecture needs a pulsed laser.
Sure. So you need more power.
Add to that the fact that a spacecraft isn't going to go straight up into orbit, it's going to follow a slanting path that could have a laser firing through 100-200 miles of atmosphere before it even touches the spacecraft, and THEN it actually has to still have enough energy to propell the craft. This is a HUGE problem that simply cannot be gotten around by anything other than brute forcing the laser output.
Sure so add more power.
Even adaptive optics will only get you so far. The power requirements would be orders of magnitude beyond anything even on the drawing board today, and the cost would be appropriately astronomical.
Nah. Semiconductor lasers cost about $10/w right now, and dropping about 30% a day. The optics aren't, but you can get quite a few lasers per optics, so I think the lasers dominate. That means for 100 Mw you are talking about $1 billion. But this compares not unfavourably with the cost of 2 space shuttles; and the actual vehicles can have few moving parts.
The heat exchanger is not a huge problem- the heat flow is comparable to the heat flow that a microprocessor heatsink sees in fact. And you have to compare this with turbopumps- with this system no turbopumps are needed; it's a laser powered pressure fed rocket in fact; with a high ISP.
The most practical craft design I've seen suggested, which has flown in small-scale tests, has the bottom of the craft being a curved mirror with a central projection. The laser is focused by the mirror and heats air immediately below the central projection, which is shaped to force the air to move away from the craft.
I'm not sure that's really practical as it stands. Nobody has or can afford a pulsed laser of the required power, and nobody is planning to build one. Secondly, this is purely an airbreathing design- as such it cannot make orbit (the 'orbital version' has extra tanks). Thirdly it requires a laser pointing from directly below, but 93% of achieving orbit involves sideways motion. Still, variations of these ideas may make orbit, but they are all then much more complex.> Fuel is dirt cheap, but handling the fuel and storing the fuel and using the fuel to launch the
>fuel to launch the fuel to launch the fuel is not cheap.
There's some truth to this- but for dense fuels such as kerosine/lox or kerosine/HTP the handling issues are not too great; and the higher thrust levels allow you to lose the fuel lower down, which minimises the gravity losses.
>The extra mass does not cost you fuel. The extra mass costs you PAYLOAD.
Well, if you keep the same vehicle mass but if you don't it's much more debatable; and why would different vehicle designs have the same mass? Does it cost you payload for the same price?
>1) SSTO doesn't make sense, because you have to schlep a lot of dead weight into orbit with you.
>Once the fuel tank is empty, it's just drag and extra mass. Pitch it.
True if the vehicle isn't reusable. Otherwise, you a) need another tank b) you need to pay a wrench monkey to slap a new one back on c) the detach mechanism can go wrong (then what?) d) the extra mass mostly just costs you fuel- but fuel is dirt cheap compared to the tank. (The space shuttle main tank costs what? $100 million?) These may well be carbon fiber wound tanks... they aren't cheap.
>2) Reusable hasn't yet made sense, because it's almost less expensive to build a new one than to
>re-certify one for flight
Yes. Although a datapoint of one (skipping over Buran, since it wasn't reused) isn't enough to draw a graph, so we don't know whether this is generally true of reusable launcher designs.
>It's good to hear that someone's worked on the problem a bit. Still, I'm sure it's quite expensive.
A little. Actually the X33 architects blew this one. The hypothetical story I heard goes:
We want a lightweight cryo tank!
Ok, no problem! We've got these aluminum tanks. It's gonna cost a little.
No, we need it to be composite!
Ok, you must like pain! It'll cost more! So it's axially symmetric of course?
No, its a funny kidney shape!
Ok, you must *really* like pain. It's gonna really really cost you!
(The Roton tank was axially symmetric of course.)
>I will point out that the payload capacity you're speaking of is about a tenth of what one Saturn V
>can hurl into LEO.
Yeah. So? The cost per kg is 1/10 of the Space Shuttle. Cost per kg is a pretty reasonable metric. So you go there and back 10x and assemble on orbit.
>Ground based lasers will always be subject to thermal blooming due to atmospheric attenuation.
Interesting. Is this caused by the lasers or just natural artifacts of the atmosphere? Incidentally power is the cheap bit in the equation, and you need less of it delivered at altitude due to g-limiting anyway; so it may not matter.
> I understand the space savings advantages of kerosene, but how does the thrust produced per unit
;-) [In fact that's partly why you need the SRBs otherwise it couldn't physically take off- it's too heavy].
>weight compare to that of the current SRB/LRB compare?
Atleast one kerosene engine has a thrust to weight ratio of upto 130:1, and all I'm aware of are atleast 100:1. The SSMEs have a thrust to weight ratio of only 70:1. Space Shuttle loses big time
The reason is that hydrogen is seriously not very dense. So all the plumbing in the engine needs to be much bigger diameter to be able to carry the propellent flow to give the thrust. Also the tank gets huge. The extra weight is significant to the vehicle performance- you carry that engine and tank basically all the way to orbit, and it costs... This is partly offset by the greater ISP of the hydrogen, but it's at best neck and neck with hydrogen.
>Having to (hypothetically) double the fuel weight to double the thrust seems like a waste of money to me.
Fuel is irrelevant right now. Tanks and engine mass and costs are where its at. Kerosene has a lower ISP and that translates to more mass. But the greater density and the greater thrust means that the gravity losses are less (you don't carry the fuel as high before burning it) means that kerosene/LOX is excellent for a first stage. Saturn V worked this way for a reason. And if you SSTO, then you don't need hydrogen at all.
> Unfortunately given our current level of rocket
> propulsion technology a single-stage-to-orbit
> (SSTO) isn't terribly practical. They made some
> prototypes and actually flew a scaled down
> prototype in the desert, but ultimately they had
>tremendous problems with the extremely high
>performance rocket engine they had to use, couple
>with the experimental composite cryogenic fuel
>tanks.
No. This isn't the case; I was talking to some engineers that worked on the Roton just last weekend. They indicated that they knew of no problem that would have precluded the design from working. The composite cryogenic fuel tank THEY used (as opposed to the X33 debacle) - it worked fine in all testing; including something like 50 pressure cycles IRC.
>I honestly don't think we'll ever get SSTO going
>with conventional chemical propellants. You simple
>have to carry too much weight in fuel, which means
>you need a bigger rocket, which means more fuel,
>then a bigger rocket...you get the idea.
No, the simulations converge- SSTO is definitely possible. I've seen atleast 2 hard and fast designs for SSTO vehicles- the Roton and Mockingbird. The Roton would have carried 3 tonnes to LEO; the Mockingbird design didn't have a payload of any note, but was really tiny (1.5 tonnes), and cheap. I've studied both concepts extensively; they both appear workable.
The biggest argument against SSTO is that it may be more expensive. TSTO may be cheaper. Still, the argument isn't totally watertight. There's a lot of ground processing for TSTO that SSTO doesn't require and that's going to cost something. Although SSTO designs use more fuel- fuel is cheapest bit of the whole rocket by far.
>What we need is a way to extract more energy from
>whatever fuel we use.
Another thing I saw on the weekend- I was at a presentation by a guy talking about a laser powered launch system. The idea is you take a large bank of lasers and point it at a hydrogen powered launch vehicle, which has a heat exchanger it uses to heat the hydrogen. The ISP is about 600 seconds, which is plenty for reaching orbit. The laser bank was priced at about $1 billion but its dropping at about 30% a year currently- only cheap semiconductor lasers are needed, and they're getting cheaper and cheaper.
Nah. Nobody clever enough to come up with the lines that he did could have really believed this stuff- it's too inventive; he'd have to have thrown too many bits away that he couldn't use. But he probably doesn't care if it's all made up- as long as it sounds right it serves his purpose...
>Legally, you can copy software all you like. You just can't distribute those copies.
Actually no. Copyright is about the right to make copies, not distribute it. And all software is by default, copyrighted by the author. Without a license to say you can copy it; you have no rights to make other copies at all, for any purpose.
In fact it has been ruled that even loading software into your computer is an act of copying it into the memory, so you can't run software without a license (legally).
In that case I'd like to be the first person to complain about flocks of geese looking like soviet nuclear missiles...
A guy I work with has a PhD in image processing. He relates this story of a system that was designed to try to detect human beings, and raise the alarm so that a security guard could check it out; rather than have a security guard staring at it continuously.
Anyway, they wrote some software- it more or less just looked for a human sized blob that moved. Worked too- it could detect human beings pretty well.
Trouble was, they found that it was unreliable- it tended to think birds landing in flocks and groups were people appearing and disappearing. So they improved on the algorithm, and put in some code that if the system could see the wings flapping- it would realise it was birds and ignore it.
Anyway, it worked pretty well, so they thought they'd give a hard test. Could someone deliberately evade it? They got a grad student and told him to work out a way to fool it. They set up the computer guarding a notional prize, and set him at it.
The grad student puzzled over it for a while, then siddled into the middle of view; and removed his jacket. He then waved his jacket over his head vigorously. The computer saw all the flapping, and activated the 'bird' assignment and he was able to steal the item...
Ok, some pedantry needed here. It's not free. You've paid something for the WAP. Actually, I suspect it's fairly expensive according to some measures; but then again if you need it for your own stuff, it doesn't matter much does it?
How do you measure cost effectiveness? cost/area/achieveable bitrate might be a good metric. Wonder what the metric for cell phone masts would be. Those cells are measured in tens of miles, whereas most WAPS can do 100m or so can't they? That's 10,000x more area covered for a cell phone.
Hmm. Wonder how much a mast costs to put up; if it costs a million then it might be comparable. Interesting. Suspect a cell mast is cheaper than that though, but the WAP costs should be coming down too.
Um. Hate to break it to you. That's caused by the slow seek time, and to some extent, the CD rom standard.
Unlike a hard drive where it can get to a block in maybe 8.5ms or so; the CD needs 10s of times longer. This is particularly crucial when your OS is mounting the CD for the first time.
I think wireless is easier to deploy- no drilling, no unsightly cables, you can use your laptop on the same lan, it covers a wider area, and ad-hoc connectivity is easier.
There's nothing wrong with ethernet though. Its just more cumbersome. Potentially faster, 100 or 1000 M if you need that. But mostly, I find I don't. The only time I thought this would be useful was for a huge compile I was working on (115+ M bytes). There, not having 100M ethernet to my file server costs me about 3 minutes on a ~10 minute link; I was using 10 base T. But I don't think that's such a common thing.
>As the article mentions, the 2.4 GHz band is slowly being used for more and more transmissions.
>Unless we regulate usage in some way, the wireless world will become impossible to achieve, as the
>noise would be too great.
You call that noise? I call that connectivity! Why shouldn't I use them for accessing the internet? The 2.4 Ghz air waves are free; even if the backbone isn't. Why shouldn't they use me? It isn't necessarily the case that because they use my equipment, I pay for their traffic; our ISP can have them sign on through a firewall (VPN) and ensure they don't use more traffic per second than they've paid for.
If the 2.4 Ghz band is becoming used for more transmissions; that's largely a good thing. Multistandard transmitters are already appearing.
>Once you DO have such a network, however, control becomes an issue. If the network is privately
>controlled, someone could be making a bundle off of everyone's usage."
I expect that it may be simply free, i.e. paid for via other means. The roads could be like that too, except the government levies a tax which is (in the UK) about 10x the amount they actually spend on the roads. Otherwise, it will be a once a year/month licence no doubt.
>If the government controlled it, it could be used for propaganda.
Yeah right. So you've grown the internet via wireless tech and suddenly the whole internet is either owned by someone OR (exclusive OR?) its all just government propaganda?
Really? I don't think so...
On the contrary, the wireless node can be 100% secure (VPN software to get onto the internet + firewall that you have to log in via), so they have to log on; and you can put on traffic shaping.
Besides, bandwidth is rapidly getting cheaper and cheaper. The cost halves ever few years as the fiber optic backbones deliver lower cost per bit; DWDM, greater range and so forth; and there's a long way to go yet on that front I'd bet.
$1 to $2 per gigabyte is still pretty cheap; it's about as cheap as a CD-R. At 576k it would take me hours to download that much even maxing out the link. Even a $5 a day bill for an internet cafe does not seem outrageous if it pulls in a few more punters; it would atleast break even, and that's pretty worst case I would think.
Well, it's wireless, and you may be able to daisy chain through multiple devices (e.g. repeaters) to go longer distances. Also, this is probably a battery powered technology. Pricing depends more on how many of these devices get built, and it's potentially quite a cheap technology in fact.
Yeah, nice idea. When your first passenger idly opens the compartment and takes a secret swig whilst you pop into a 7-11 or something and then, like, DIES.
Plus, in the eyes of the law, even for thieves; killing isn't considered to good for them; it's too bad for you- you're going DOWN.
Or when the thief doesn't like whiskey and gives it to his sister...
I'm not so sure. I heard about atleast one experiment where they looked at two different universities. In one Napster use was rife. In the other it was banned. In the latter the shops around the university had a 2% reduction in sales relative to the previous year. In the one which had Napster, the sales were the same as the previous year. The music industry claimed that the fact that sales were flat proved that Napster was reducing their profits.
Ur. Come again? The yearly sales were down in the control group and stayed the same in the experimental group; therefore Napster actually increased sales by 2%! Only 2%? Still, even if that was experimental error- the experiment showed absolutely no evidence that Napster had hurt sales. None. Nada, zip zero.
I personally download a fair amount of music. If I like the music I often buy the CDs. Not EVERY time, but I'm pretty sure I buy more CDs because I listen to more music.
In a pretty real sense P2P software is self advertising for music. To some extent, to make informed decisions on what to buy, some other people DO use these technologies to rip off the distributors. But so far as I can tell, that is almost exactly balanced by the self advertising aspects. Of course the distributors are looking at this tech, and thinking "How can we screw more money out of people with this stuff", but my suspicion is that they can't.
People have a sort of built-in sense of how much money they are comfortable in spending on music, based on how music interworks with their self image. I think that's what the record companies do, they sell the image for the music.
Essentially, buying a CD is like tipping the record company and artist; and always has been really. You almost never HAVE to buy a CD in the modern world. You can tape it off the radio or TV and listen to it later. You've been able to do this for decades. Is this illegal? Yes, just barely, sometimes, or else it's just time shifting, which is actually legal. Downloading off of a computer is only a bit more convenient. People who do that often buy stacks of legitimate music too. So the record companies have done well; I don't see this changing, unless they succeed in banning music sharing. People will probably tend to spend the money on other things then, video games or whatever.
Hmm. I don't think I'd be boasting about it if MY son failed the Turing test! ;-)
Ok, if nobody else eats all the food they bought, then is it ok if I eat it? That seems reasonable. But obviously if everyone rushes for the food when it gets laid out, the restaurant may not be able to physically lay the food out fast enough- so they have 'fight over the food' clauses.
So it's not 'all I can eat' exactly, there's a maximum I can eat because of the size of the plates they give you.
And further the restaurant doesn't in fact guarantee all you can eat in the first place; they only guarantee all I can eat upto a low limit 1/50 of the plate size; generally they'll try to fill my plate, particularly if no one else is eating, but they only guarantee 1/50 of the plate.
This being the case, I fail to see why the restaurant should impose restrictions on the food I eat; any food you want provided it isn't green! Why? "Cause I don't like it when you eat green food cos you eat more green food normally." Huh? If I'm consistently eating more than 1/50 of my plate, they're quite at liberty to limit me; within reason. However, if theres no rush on, then what do they care? The restaurant has already bought in the food from their supplier when I entered the restaurant... and for most normal people that's plenty of food. But if they decide to charge me extra 'because you're being too greedy'; tell me again who's being greedy? Why didn't you invoke my 1/50 limit then?
Not quite sure what the H2 is for in your scenario. There's massive deposits of methane under the ocean for example. So why make it from H2?