Encrypted key exchange algorithms such as SRP and SPEKE provide strong password authentication which is resistant to all known passive and man-in-the-middle attacks. An added benefit is that they authenticate the server to the client as well as the other way around. And all this is done without PKI and without even requiring particularly strong passwords.
Why are they not in widespread use? It might have something to do with the fact that (AFAIK) all these algorithms are patented. SRP is patented by Stanford but apparently they allow it to be used without licensing fees in free software.
Another problem is that these algorithms cannot be used with the existing password databases. Replacing critical components such as/etc/shadow, passwd and requiring all users to change their password to move to the new system is never going to be very popular with system administrators.
"comparing the BlackJack to an ordinary GPS receiver is like comparing a home camcorder to a professional studio camera"
This isn't such a good analogy because home camcorders now have exceptional quality and often surpass the performance of professional gear that is just a few years old...
I am not sure where you got the idea that I disagree. My position is that I simply don't know and I am not really qualified to have a strong opinion either way.
What really bothers me is the attitude of the scientific establishment and the environmental lobby towards the dissidents. They have a valid opinion that needs to be investigated properly. Instead they are ridiculed, denied grants and instead of countering their claims their opponents often resort to personal attacks. "Everyone knows that the ozone hole is a result of CFCs" and anyone who says otherwise is therefore insane. But how come "everyone" knows that? From a sensationalist newspaper article quoting a controversial study it suddenly becomes Instant Truth - maybe because it fits the agenda of some very powerful organizations.
From my point of view, both sides are still theories that need more proof and deserve further efforts.
There are quite a lot of scientists who say that the ozone hole over antrarctica has nothing to do with CFC emissions. They claim that volcanos emit 600 times more ozone-killing chlorine into the atmosphere per year than the entire CFC production of mankind at its peak.
Ozone is created by sunlight. Sunlight is abundant near the equator where light hits the atmosphere at higher angles and that's where most of the ozone is created. Ozone coverage above the pole depends on whether there are enough jet streams to get it from the equator to the poles. The ozone heretics claim that a well-known priodic weather phenomenon over the south pole creates a pocket of air that doesn't interact much with the rest of the atmosphere and that is the real reason for the hole. This pocket is occasionally broken up by atmospheric turbulence and fresh ozone gets to the pole.
Even if the ozone heretics are correct and all the environmental scientists and world governments are deluded perhaps this is still a Good Thing: it's the first time that people realize that their actions have global consequences and that they can actually make a difference by changing their behaviour. If global warming is real (and there are enough scientists who claim it isnt...) people could point to the ozone example and show that "it worked".
This reminds me of the windup radio developed by Trevor Baylis for use in regions such as Africa where radio is the primary method of distributing important information but electric power and even batteries are difficult to get.
The windup radio was sold in the west for a pretty high price as a curiousity to subsidize the distribution of these radios in Africa.
The Pengachu has short-range IP wireless commuication. What about wide area communication in infrastructure-poor areas? The two options I can see:
1. Satellite communication - a VSAT terminal that is shared by multiple Pengachus using the short range wireless link.
2. Terrestrial radio. Yes, this is one-way, but it's a very cheap and effective way of distributing information, software upgrades, etc. You can piggyback the data onto existing transmitters (RDS for FM, phase modulation a-la AM stereo for AM)
On Earth metals are found almost exclusively in the form of oxides, sulfides, etc. These compounds are lighter and therefore floated to the surface as the Earth formed. Metals in their heavier elemental forms are at least hundreds of miles below the surface.
Producing the elemental form of a metal from these compounds is a pretty simple chemical reaction. For example, iron oxides are reduced using carbon, producing iron and CO2. Unfortunately, this means that a vast amount of CO2 is released to the environment in the process. There are no shortcuts and no significantly cleaner ways to do it - it's basic chemistry. You get a few kilograms of CO2 for each kilogram of steel you produce. Add do that the energy required in the process which is usually also produced by burning fossil fuels and you end up with around 20 kilograms of CO2 for each kilogram of steel. Take a moment to think about the weight of your car. The emissions it will produce over its entire lifetime are about the same magnitude as the amount produced just in reducing the metal, not to mention the environmental cost of producing other parts.
Some asteroids were large enough (and hot enough) for the lighter compounds to float to the surface. After they cooled down they were struck by other asteroids and the chunks that came from their cores are almost pure elemental metals.
Getting them closer Earth is the tricky part. The delta-Vs required not too high for some of the asteroids, though. The cheapest and most practical method of slowing them down as they approach the Earth is aerobraking. I suspect that this solution will not be too popular, though...
The first person to fashion a statistical foundation for this assumption was the British gentleman scientist Sir Francis Galton. He calculated the probability that any two fingerprints would resemble each other in all particulars as one in sixty-four billion.
Even if you accept this figure of one in 64 billion the birthday paradox predicts that you can expect to find an identical pair of fingerprints in a database of sqrt(64e9) fingerprints which is just a little over 250,000. I believe the FBI fingerprint database is significantly larger than that. After this "threshold" of sqrt(N) is crossed the number of duplicates starts to rise quite sharply as the database size increases.
While your explanation of damage control is quite plausible I can see an alternative explanation:
1. Breach is first detected, everyone is in a panic and assumes the worst.
2. After a little checking it turns out not to be as bad as they thought at first.
3. After careful analysis of logs, including the version control management logs it turns out that no modification took place and only a minor future product has been downloaded.
Bell had several (government sanctioned) patents, central among them was the patent on loading coils that reduce the high frequency rolloff on long lines. These patents protected it from competition long enough to become an extremely powerful monopoly.
Later it got further government protection with the excuse being "universal service". The benefits it got from its government protected monopoly far exceeded the costs of having to supply telephone service to remote and unprofitable clients.
The government only stepped in to break the monopoly it has created after decades of uninterrupted operation at unreasonable prices.
On the question of intellectual property Harry Browne just recites the libertarian mantra that free markets can handle it. I believe a truly freedom oriented society could live very well without copyright and patent laws. But it would still need trademark laws.
According to libertarian principles people are free to do anything they want as long as it does not involve force or fraud. Trademark law is extremely important in facilitating a society with a lower rate of fraud. Remember that I am only talking about the original sense of trademark where you cannot sell or advertise a product that is likely to be confused with my trademark. Later perversions of trademark law not included. If you make someone buy your product or service believing it is my product or service this is fraud.
Hushmail has a feature that allows reading your email with standard POP clients isntead of their web-based applet interface. Unfortunately, it is for Windows machines only at this stage. Any chance they might release a pure java version? (it's implemented mostly in Java)
Freezing damage to cells is caused by ice crystals. When you freeze something really fast it forms amorphous ice without crystals. A sperm cell is small enough to be frozen instantly when you dip it in liquid nitrogen. A human body is a little bigger. The flow of heat out out the body into the nitrogen is gradual and the temperature of internal parts drops slowly enough for ice crystals to form.
During cryonic freezing of humans they attempt to minimize this damage by replacing most of the water in your body with other fluids. Of course, it's difficult to replace all water so substantial damage is still caused. With current cryonic freezing techniques it will probably take some of Drexler's little helpers to repair the damage for reviving the individual.
The 'selection bias' is not a problem - it is actually the whole point.
Suppose that you've just won the lottery. You have correctly guessed 6 numbers out of 46 (or whatever). I imagine you'd be quite surprised. You might even be inclined to think that it wasn't really chance, that some external factor has intervened (your lucky star, guardian angel, etc).
The photographer that has just taken your picture with the check and a big smile is not really surprised. He knows that out of so-and-so millions of people that buy lottery tickets each week it's likely that someone will get it right and he'll be taken to visit him and take some pictures of the lucky bastard.
Some people look at the unlikelyhood of life, the universe and everything and assume that it's too unlikely to have happened by chance so there must be some external intervention (a deity, for example). In other words, they think they have just won the lottery. But mankind is not really the loterry winner. We are the photographer. We have been taken to visit the universe that won the lottery and we shouldn't be surprised at all.
Now if you knew that only 10 other people bought tickets and you still won you'd be justified in being surprised.
Let us assume that the winner has never left his home and is completely isolated from the world. He has no way of knowing how many others bought lottery tickets. Ask him to estimate how many other bought tickets. A good estimate would be a number greater than 1/P where P is the probability of guessing the right numbers. He can make this estimate without having any knowledge whatsoever about the others other than knowing the probability and knowing that he is the winner.
We have no knowledge about other universes in the multiverse of even if this number is greater than 1. But we do know that we live in a winning universe. In this case a good guess for the number of universes would be 1/P(life). We have no way of knowing what the probability of life really is but since it requires many different conditions, each one of them has a probability lower than unity it looks like their product should be "pretty low". So according to this logic the number of universes in the multiverse is quite likely to be greater than 1/"pretty low == "pretty high". If the number of universes is likely to be much greater than 1, do we have any reason to assume it is finite at all?
Now, for the second problem:
It would be pretty chauvinistic to assume that ours is the only type of life possible. But it's pretty hard to imagine anything remotely resembling anyone's definition of life in a universe consisting entirely of hydrogen.
Life is one of a group of phenomenona that happen on the middle of the entropy scale. On one extereme end the scale is close to zero entropy. Imagine a universe of iron at a temperature infinitesimally close to the absolute zero. There's nothing interesting happening there. The structure is a perfect regular crystal carrying no information. On the other end of the scale imagine a universe filled with a churning particle soup at extremely high temperatures. Here there are no structures. Nothing can be stable for any length of time.
Life, evolution, intelligence, society, all the things we have come to value, they all occur on a very narrow "visible light" band in the middle of this spectrum, on a precarious balance between chaos and order.
Please take a moment to appreciate how delicate this balance really is. Think about it whenever you are in an argument that revolves around the conflict between the forces of change and the forces of conservation. For example, think about Andy Mueller-Maguhn being elected for the ICANN board. Andy is ever so slightly closer to high entropy end of the scale, to the high temperature particle soup. The "suits" on the board are ever so slightly slightly closer to the universe of iron at absolute zero. But they are infinitely closer to each other than to either of those exteremes.
Everything we know happens in this narrow band in the middle of the scale. If the laws of physics were slightly different the universe could have easily been tipped one way or the other and this band wouldn't exist. Life, whether similar to ours or vastly different could not exist.
I can already see the luddites shouting about how dangerous it can be and how science should let it rest. However, this kind of thing has undoubtedly happened many times by chance: an ancient salt deposit is flooded after an earthquake, awakening ancient bacteria. If these bacteria are dangerous they are probably already here anyway.
Rejection of IP is can be considered "communism" only if you accept the fallacy that IP is really property. IP is not property, it's a deal.
In case of patents the terms of the deal go this way:
"Make the details of your invention publicly known and in return we will give you a limited period where you can use the powers of our courts to harrass people who use your invention without your permission."
Do you see any property here? I don't. In the past, this deal has had an overall positive effect on innovation and society. In recent years the interpretation of the terms of the deal has taken a bad turn, though.
Virtually all audio A/D and D/A converters today use sigma-delta, also commonly referred to as "one-bit" conversion.
In a sigma-delta A/D converter the audio signal is sampled with a high sampling frequency (typically a few MHz) and low sample resolution (1 bit). An error feedback mechanism is used to ensure that most of the energy of the quantization noise is "shaped" into high frequencies, giving excellent fidelity in the audio band. One bit is inherently linear - no need for carefully matched resistor networks such as those used on older A/D converters. This stream is then filtered and decimated using digital signal processing techniques to a lower sampling rate (e.g. 44100Hz) while gaining sample depth on the way (16 bits and higher).
For D/A conversion the process is reversed: the 44100Hz signal is interpolated up to a high sampling rate and then the sample depth is reduced down to one bit. Again, error feedback is used to ensure that the quantization noise resulting from the low resolution is shaped to high frequencies. This bitstream is then low-pass filtered and used as the audio signal. Again, with much better linearity than D/A converters based on carefully adjusted resistor networks.
The Sony SACD skips the decimation and interpolation stage. It stores the noise-shaped bitstream directly on the disc. The beauty of this idea is in its simplicity: it performs much less transformations on the sigma-delta signal and therefore should offer inherently higher fidelity and wider bandwidth.
If sigma-delta converters were available 20 years ago when the CD was invented they would probably have chosen this method for its simplicity. But at that time the analog conversion technique known was resistor networks so PCM was used.
Remember that at the time the CD was really stretching the limits of consumer technology. No other consumer product prior to the CD player used so many new and advanced technologies: lasers, error correction, digital signal processing. If they could have used this technique it would have reduced the cost of CD players significantly. For example, this bitstream is much more tolerant to bit errors because unlike PCM there is no "most significant bit" that can cause a large error if corrupted.
Using this technique today, though, is insane. There is no real savings in simplicity when a million digital transistors cost close to nothing. If you want higher fidelity, 96kHz and 24 bits is more than enough.
Let's say you want something simple like a graphic equalizer on your SACD player. If it's analog such a complex circuit will introduce lots of noise. If you implement it digitally it would take insanely large amounts of CPU power to process a signal sampled at over 2mHz. Manufacturers will probably end up downconverting it to PCM at 96kHz or lower, doing the signal processing and then converting back to sigma delta for playback. This will lose all of DASD's alleged advantages.
BTW, for the purpose of preserving analog masters DASD is really a good idea because they contain useful information at very high frequencies such as the tape bias signal and the intermodulations it creates. Preserving this information will allow future signal processing techniques to create accurate models of the nonlinearities of the magnetic medium and use this high frequency information to reconstruct the original recording with better fidelity down in the audio band. For home use SACD is a very bad idea. Just about the only good thing I can see about it is that it can be marketed effectively because it's such a "radical new concept".
The DVD audio uses conventional, well proven PCM with somewhat higher sampling frequency and bit depth than CD. Why use a higher sampling frequency when we can't hear over 20kHz? It turns out that while we can't hear a sinewave at frequencies higher than 20kHz the high frequency components of complex waveforms make a noticable difference even up to 26kHz. To take a good safety margin and maintain integer ration a 96kHz sampling rate was used. This does not significantly hurt the data rate required because non-lossy compression is used on DVD audio. A compressed 96kHz signal takes about 30% more space than a compressed 48kHz signal. 16 bits is, again, almost enough. In fact, with proper in-band noise shaping the noise floor is inaudible in all but very extreme circumstances. 24 bits is therefore a very good safety margin.
Another reason why DVD-audio is superior is because it supports Ambisonics. Ambisonics is a surround sound system. It was not crated for cinematic effects. Ambisonics was designed for music and for reconstructing the subtle spatial cues of the ambience of the recording venue. With a proper arrangement of speakers it can create true 3D sound - including the height dimension. Imagine listening to a recording and feeling the height of the concert hall!
Please never ask "how many channels does Ambisonics use" because it's not a relevent question. Ambisonics deconstructs the 3D sound field mathematically using a four component representation (XYZW). This representation can be processed with a simple linear matrix for playback on different speaker configurations and numbers of channles with varying levels fidelity of 3D soundfield reconstruction. This includes the popular 5.1 setup used on home theaters (it's probably going to be the default settings for DVD-Audio players) .
DVD-Audio is also backward compatible with DVD players although a DVD-audio player will be required to take advantage of all the features and full quality.
Most of the martian atmosphere is in the form of frozen CO2. All you need to do is keep the CFC production long enough to start the evaporation of this CO2 into the atmosphere. Since CO2 is a greenhouse gas itself the process will be self-sustaining until in about a century most of the CO2 goes back into the atmosphere.
Radiation. There is strong radiation from both the sun an cosmic rays. For a short mission like a two year mission to Mars you can probably survive the dose with only a slightly increased chance for cancer later in your life (still much less than smoking). For permanent settlement, though, you need to do something about it. There is no way to protect against cosmic rays except mass. Lots of it.
On any planet or moon you get a 50% reduction in cosmic rays for free because the bottom half is protected by an enormous mass. On a planet with an atmosphere (practically, only Mars) you also get significant radiation protection from the atmosphere.
On a floating space habitat you will need to cover it with a thick layer of rocks and any kind of junk you can find to get any kind of meaningful radiation protection. Mass is expensive in space because of the delta Vs required to get it where you want it, but it is very cheap on a planet.
Getting direct sunlight for agriculture is more diffcult because you want your protective mass to be transparent. The window panes of agricultural areas will need to be over a foot thick.
Except for radiation protection you will need mass for everything you build, eat or breathe and all of it requires significant delta Vs. Oh, I almost forgot: you also need lots of reaction mass as fuel for generating these delta Vs.
I find the point about absence of pests to be particularly ironic considering the fungus problem on Mir. If you start to do agriculture it is likely to get worse. Perfect quarantine is impossible and once a pest gets there it can get pretty nasty. If you decide that your agriculture areas do not need as much radiation protection as the habitable areas you will get very interesting mutations, too.
Eventually we will probably see both free space and planetary settlements filling different niches in the economic ecology of space.
and will continue to be "experimental" for as long as people buy into this snake oil stuff.
Walker's first patent for this "technology" has been filed in 1986 and he has probably been working on it for a while before that.
I am familiar with this type of personality - the more refusals they get the more they believe they are some kind of Galileo that one day will be vindicated. The problem is that for every Galileo that is eventually proven to be right about the Earth not being the center of the universe there are a hundred crackpots that believe all kinds of bullshit with the same amout of self conviction.
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Encrypted key exchange algorithms such as SRP and SPEKE provide strong password authentication which is resistant to all known passive and man-in-the-middle attacks. An added benefit is that they authenticate the server to the client as well as the other way around. And all this is done without PKI and without even requiring particularly strong passwords.
/etc/shadow, passwd and requiring all users to change their password to move to the new system is never going to be very popular with system administrators.
Why are they not in widespread use? It might have something to do with the fact that (AFAIK) all these algorithms are patented. SRP is patented by Stanford but apparently they allow it to be used without licensing fees in free software.
Another problem is that these algorithms cannot be used with the existing password databases. Replacing critical components such as
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"comparing the BlackJack to an ordinary GPS receiver is like comparing a home camcorder to a professional studio camera"
This isn't such a good analogy because home camcorders now have exceptional quality and often surpass the performance of professional gear that is just a few years old...
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I am not sure where you got the idea that I disagree. My position is that I simply don't know and I am not really qualified to have a strong opinion either way.
What really bothers me is the attitude of the scientific establishment and the environmental lobby towards the dissidents. They have a valid opinion that needs to be investigated properly. Instead they are ridiculed, denied grants and instead of countering their claims their opponents often resort to personal attacks. "Everyone knows that the ozone hole is a result of CFCs" and anyone who says otherwise is therefore insane. But how come "everyone" knows that? From a sensationalist newspaper article quoting a controversial study it suddenly becomes Instant Truth - maybe because it fits the agenda of some very powerful organizations.
From my point of view, both sides are still theories that need more proof and deserve further efforts.
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There are quite a lot of scientists who say that the ozone hole over antrarctica has nothing to do with CFC emissions. They claim that volcanos emit 600 times more ozone-killing chlorine into the atmosphere per year than the entire CFC production of mankind at its peak.
Ozone is created by sunlight. Sunlight is abundant near the equator where light hits the atmosphere at higher angles and that's where most of the ozone is created. Ozone coverage above the pole depends on whether there are enough jet streams to get it from the equator to the poles. The ozone heretics claim that a well-known priodic weather phenomenon over the south pole creates a pocket of air that doesn't interact much with the rest of the atmosphere and that is the real reason for the hole. This pocket is occasionally broken up by atmospheric turbulence and fresh ozone gets to the pole.
Even if the ozone heretics are correct and all the environmental scientists and world governments are deluded perhaps this is still a Good Thing: it's the first time that people realize that their actions have global consequences and that they can actually make a difference by changing their behaviour. If global warming is real (and there are enough scientists who claim it isnt...) people could point to the ozone example and show that "it worked".
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This reminds me of the windup radio developed by Trevor Baylis for use in regions such as Africa where radio is the primary method of distributing important information but electric power and even batteries are difficult to get.
The windup radio was sold in the west for a pretty high price as a curiousity to subsidize the distribution of these radios in Africa.
The Pengachu has short-range IP wireless commuication. What about wide area communication in infrastructure-poor areas? The two options I can see:
1. Satellite communication - a VSAT terminal that is shared by multiple Pengachus using the short range wireless link.
2. Terrestrial radio. Yes, this is one-way, but it's a very cheap and effective way of distributing information, software upgrades, etc. You can piggyback the data onto existing transmitters (RDS for FM, phase modulation a-la AM stereo for AM)
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On Earth metals are found almost exclusively in the form of oxides, sulfides, etc. These compounds are lighter and therefore floated to the surface as the Earth formed. Metals in their heavier elemental forms are at least hundreds of miles below the surface.
Producing the elemental form of a metal from these compounds is a pretty simple chemical reaction. For example, iron oxides are reduced using carbon, producing iron and CO2. Unfortunately, this means that a vast amount of CO2 is released to the environment in the process. There are no shortcuts and no significantly cleaner ways to do it - it's basic chemistry. You get a few kilograms of CO2 for each kilogram of steel you produce. Add do that the energy required in the process which is usually also produced by burning fossil fuels and you end up with around 20 kilograms of CO2 for each kilogram of steel. Take a moment to think about the weight of your car. The emissions it will produce over its entire lifetime are about the same magnitude as the amount produced just in reducing the metal, not to mention the environmental cost of producing other parts.
Some asteroids were large enough (and hot enough) for the lighter compounds to float to the surface. After they cooled down they were struck by other asteroids and the chunks that came from their cores are almost pure elemental metals.
Getting them closer Earth is the tricky part. The delta-Vs required not too high for some of the asteroids, though. The cheapest and most practical method of slowing them down as they approach the Earth is aerobraking. I suspect that this solution will not be too popular, though...
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Even if you accept this figure of one in 64 billion the birthday paradox predicts that you can expect to find an identical pair of fingerprints in a database of sqrt(64e9) fingerprints which is just a little over 250,000. I believe the FBI fingerprint database is significantly larger than that. After this "threshold" of sqrt(N) is crossed the number of duplicates starts to rise quite sharply as the database size increases.
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It might not be a coincidence that in most democratic countries there are exactly TWO large political parties.
It is probably not a coincidence that the open source world has TWO major desktop environments.
2 is the smallest number larger than 1.
Would you like to live in a country where there is just ONE large political party?
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SkyStation.
Uses a lighter-than-air solar powered helium airship.
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While your explanation of damage control is quite plausible I can see an alternative explanation:
1. Breach is first detected, everyone is in a panic and assumes the worst.
2. After a little checking it turns out not to be as bad as they thought at first.
3. After careful analysis of logs, including the version control management logs it turns out that no modification took place and only a minor future product has been downloaded.
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Bell had several (government sanctioned) patents, central among them was the patent on loading coils that reduce the high frequency rolloff on long lines. These patents protected it from competition long enough to become an extremely powerful monopoly.
Later it got further government protection with the excuse being "universal service". The benefits it got from its government protected monopoly far exceeded the costs of having to supply telephone service to remote and unprofitable clients.
The government only stepped in to break the monopoly it has created after decades of uninterrupted operation at unreasonable prices.
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On the question of intellectual property Harry Browne just recites the libertarian mantra that free markets can handle it. I believe a truly freedom oriented society could live very well without copyright and patent laws. But it would still need trademark laws.
According to libertarian principles people are free to do anything they want as long as it does not involve force or fraud. Trademark law is extremely important in facilitating a society with a lower rate of fraud. Remember that I am only talking about the original sense of trademark where you cannot sell or advertise a product that is likely to be confused with my trademark. Later perversions of trademark law not included. If you make someone buy your product or service believing it is my product or service this is fraud.
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Answering machines use ARAM chips which are actually faulty DRAMs. They map the defects and avoid using those areas.
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Hushmail has a feature that allows reading your email with standard POP clients isntead of their web-based applet interface. Unfortunately, it is for Windows machines only at this stage. Any chance they might release a pure java version? (it's implemented mostly in Java)
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The dates mentioned in the article are from 1998. The idea itself isn't new either. At least one person has though about it as early as 1990 (me :-)
BTW, if they wish to follow the motion of the sphere without requiring any contact they can use the same mechanism as the MS IntelliEye mouse.
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Freezing damage to cells is caused by ice crystals. When you freeze something really fast it forms amorphous ice without crystals. A sperm cell is small enough to be frozen instantly when you dip it in liquid nitrogen. A human body is a little bigger. The flow of heat out out the body into the nitrogen is gradual and the temperature of internal parts drops slowly enough for ice crystals to form.
During cryonic freezing of humans they attempt to minimize this damage by replacing most of the water in your body with other fluids. Of course, it's difficult to replace all water so substantial damage is still caused. With current cryonic freezing techniques it will probably take some of Drexler's little helpers to repair the damage for reviving the individual.
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The 'selection bias' is not a problem - it is actually the whole point.
Suppose that you've just won the lottery. You have correctly guessed 6 numbers out of 46 (or whatever). I imagine you'd be quite surprised. You might even be inclined to think that it wasn't really chance, that some external factor has intervened (your lucky star, guardian angel, etc).
The photographer that has just taken your picture with the check and a big smile is not really surprised. He knows that out of so-and-so millions of people that buy lottery tickets each week it's likely that someone will get it right and he'll be taken to visit him and take some pictures of the lucky bastard.
Some people look at the unlikelyhood of life, the universe and everything and assume that it's too unlikely to have happened by chance so there must be some external intervention (a deity, for example). In other words, they think they have just won the lottery. But mankind is not really the loterry winner. We are the photographer. We have been taken to visit the universe that won the lottery and we shouldn't be surprised at all.
Now if you knew that only 10 other people bought tickets and you still won you'd be justified in being surprised.
Let us assume that the winner has never left his home and is completely isolated from the world. He has no way of knowing how many others bought lottery tickets. Ask him to estimate how many other bought tickets. A good estimate would be a number greater than 1/P where P is the probability of guessing the right numbers. He can make this estimate without having any knowledge whatsoever about the others other than knowing the probability and knowing that he is the winner.
We have no knowledge about other universes in the multiverse of even if this number is greater than 1. But we do know that we live in a winning universe. In this case a good guess for the number of universes would be 1/P(life). We have no way of knowing what the probability of life really is but since it requires many different conditions, each one of them has a probability lower than unity it looks like their product should be "pretty low". So according to this logic the number of universes in the multiverse is quite likely to be greater than 1/"pretty low == "pretty high". If the number of universes is likely to be much greater than 1, do we have any reason to assume it is finite at all?
Now, for the second problem:
It would be pretty chauvinistic to assume that ours is the only type of life possible. But it's pretty hard to imagine anything remotely resembling anyone's definition of life in a universe consisting entirely of hydrogen.
Life is one of a group of phenomenona that happen on the middle of the entropy scale. On one extereme end the scale is close to zero entropy. Imagine a universe of iron at a temperature infinitesimally close to the absolute zero. There's nothing interesting happening there. The structure is a perfect regular crystal carrying no information. On the other end of the scale imagine a universe filled with a churning particle soup at extremely high temperatures. Here there are no structures. Nothing can be stable for any length of time.
Life, evolution, intelligence, society, all the things we have come to value, they all occur on a very narrow "visible light" band in the middle of this spectrum, on a precarious balance between chaos and order.
Please take a moment to appreciate how delicate this balance really is. Think about it whenever you are in an argument that revolves around the conflict between the forces of change and the forces of conservation. For example, think about Andy Mueller-Maguhn being elected for the ICANN board. Andy is ever so slightly closer to high entropy end of the scale, to the high temperature particle soup. The "suits" on the board are ever so slightly slightly closer to the universe of iron at absolute zero. But they are infinitely closer to each other than to either of those exteremes.
Everything we know happens in this narrow band in the middle of the scale. If the laws of physics were slightly different the universe could have easily been tipped one way or the other and this band wouldn't exist. Life, whether similar to ours or vastly different could not exist.
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I can already see the luddites shouting about how dangerous it can be and how science should let it rest. However, this kind of thing has undoubtedly happened many times by chance: an ancient salt deposit is flooded after an earthquake, awakening ancient bacteria. If these bacteria are dangerous they are probably already here anyway.
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In case of patents the terms of the deal go this way:
Do you see any property here? I don't. In the past, this deal has had an overall positive effect on innovation and society. In recent years the interpretation of the terms of the deal has taken a bad turn, though.
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Virtually all audio A/D and D/A converters today use sigma-delta, also commonly referred to as "one-bit" conversion.
In a sigma-delta A/D converter the audio signal is sampled with a high sampling frequency (typically a few MHz) and low sample resolution (1 bit). An error feedback mechanism is used to ensure that most of the energy of the quantization noise is "shaped" into high frequencies, giving excellent fidelity in the audio band. One bit is inherently linear - no need for carefully matched resistor networks such as those used on older A/D converters. This stream is then filtered and decimated using digital signal processing techniques to a lower sampling rate (e.g. 44100Hz) while gaining sample depth on the way (16 bits and higher).
For D/A conversion the process is reversed: the 44100Hz signal is interpolated up to a high sampling rate and then the sample depth is reduced down to one bit. Again, error feedback is used to ensure that the quantization noise resulting from the low resolution is shaped to high frequencies. This bitstream is then low-pass filtered and used as the audio signal. Again, with much better linearity than D/A converters based on carefully adjusted resistor networks.
The Sony SACD skips the decimation and interpolation stage. It stores the noise-shaped bitstream directly on the disc. The beauty of this idea is in its simplicity: it performs much less transformations on the sigma-delta signal and therefore should offer inherently higher fidelity and wider bandwidth.
If sigma-delta converters were available 20 years ago when the CD was invented they would probably have chosen this method for its simplicity. But at that time the analog conversion technique known was resistor networks so PCM was used.
Remember that at the time the CD was really stretching the limits of consumer technology. No other consumer product prior to the CD player used so many new and advanced technologies: lasers, error correction, digital signal processing. If they could have used this technique it would have reduced the cost of CD players significantly. For example, this bitstream is much more tolerant to bit errors because unlike PCM there is no "most significant bit" that can cause a large error if corrupted.
Using this technique today, though, is insane. There is no real savings in simplicity when a million digital transistors cost close to nothing. If you want higher fidelity, 96kHz and 24 bits is more than enough.
Let's say you want something simple like a graphic equalizer on your SACD player. If it's analog such a complex circuit will introduce lots of noise. If you implement it digitally it would take insanely large amounts of CPU power to process a signal sampled at over 2mHz. Manufacturers will probably end up downconverting it to PCM at 96kHz or lower, doing the signal processing and then converting back to sigma delta for playback. This will lose all of DASD's alleged advantages.
BTW, for the purpose of preserving analog masters DASD is really a good idea because they contain useful information at very high frequencies such as the tape bias signal and the intermodulations it creates. Preserving this information will allow future signal processing techniques to create accurate models of the nonlinearities of the magnetic medium and use this high frequency information to reconstruct the original recording with better fidelity down in the audio band. For home use SACD is a very bad idea. Just about the only good thing I can see about it is that it can be marketed effectively because it's such a "radical new concept".
The DVD audio uses conventional, well proven PCM with somewhat higher sampling frequency and bit depth than CD. Why use a higher sampling frequency when we can't hear over 20kHz? It turns out that while we can't hear a sinewave at frequencies higher than 20kHz the high frequency components of complex waveforms make a noticable difference even up to 26kHz. To take a good safety margin and maintain integer ration a 96kHz sampling rate was used. This does not significantly hurt the data rate required because non-lossy compression is used on DVD audio. A compressed 96kHz signal takes about 30% more space than a compressed 48kHz signal. 16 bits is, again, almost enough. In fact, with proper in-band noise shaping the noise floor is inaudible in all but very extreme circumstances. 24 bits is therefore a very good safety margin.
Another reason why DVD-audio is superior is because it supports Ambisonics. Ambisonics is a surround sound system. It was not crated for cinematic effects. Ambisonics was designed for music and for reconstructing the subtle spatial cues of the ambience of the recording venue. With a proper arrangement of speakers it can create true 3D sound - including the height dimension. Imagine listening to a recording and feeling the height of the concert hall!
Please never ask "how many channels does Ambisonics use" because it's not a relevent question. Ambisonics deconstructs the 3D sound field mathematically using a four component representation (XYZW). This representation can be processed with a simple linear matrix for playback on different speaker configurations and numbers of channles with varying levels fidelity of 3D soundfield reconstruction. This includes the popular 5.1 setup used on home theaters (it's probably going to be the default settings for DVD-Audio players) .
DVD-Audio is also backward compatible with DVD players although a DVD-audio player will be required to take advantage of all the features and full quality.
More information about DVD-Audio here
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Most of the martian atmosphere is in the form of frozen CO2. All you need to do is keep the CFC production long enough to start the evaporation of this CO2 into the atmosphere. Since CO2 is a greenhouse gas itself the process will be self-sustaining until in about a century most of the CO2 goes back into the atmosphere.
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Radiation. There is strong radiation from both the sun an cosmic rays. For a short mission like a two year mission to Mars you can probably survive the dose with only a slightly increased chance for cancer later in your life (still much less than smoking). For permanent settlement, though, you need to do something about it. There is no way to protect against cosmic rays except mass. Lots of it.
On any planet or moon you get a 50% reduction in cosmic rays for free because the bottom half is protected by an enormous mass. On a planet with an atmosphere (practically, only Mars) you also get significant radiation protection from the atmosphere.
On a floating space habitat you will need to cover it with a thick layer of rocks and any kind of junk you can find to get any kind of meaningful radiation protection. Mass is expensive in space because of the delta Vs required to get it where you want it, but it is very cheap on a planet.
Getting direct sunlight for agriculture is more diffcult because you want your protective mass to be transparent. The window panes of agricultural areas will need to be over a foot thick.
Except for radiation protection you will need mass for everything you build, eat or breathe and all of it requires significant delta Vs. Oh, I almost forgot: you also need lots of reaction mass as fuel for generating these delta Vs.
I find the point about absence of pests to be particularly ironic considering the fungus problem on Mir. If you start to do agriculture it is likely to get worse. Perfect quarantine is impossible and once a pest gets there it can get pretty nasty. If you decide that your agriculture areas do not need as much radiation protection as the habitable areas you will get very interesting mutations, too.
Eventually we will probably see both free space and planetary settlements filling different niches in the economic ecology of space.
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and will continue to be "experimental" for as long as people buy into this snake oil stuff.
Walker's first patent for this "technology" has been filed in 1986 and he has probably been working on it for a while before that.
I am familiar with this type of personality - the more refusals they get the more they believe they are some kind of Galileo that one day will be vindicated. The problem is that for every Galileo that is eventually proven to be right about the Earth not being the center of the universe there are a hundred crackpots that believe all kinds of bullshit with the same amout of self conviction.
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In the biblical sense?
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