This is a bit of a repeat story, so the response is worth repeating: high levels of radiation do not preclude life, and in any case the idea was that Europan life would be under kilometers of ocean.
It's amazing how much radiation certain bacteria can survive, though..
By the way, NASA is thinking about a new mission to the Galilean moons, called JIMO . Very exciting stuff - it's amazing how much more you can do with a nuclear propulsion stage.
This is what happens when an editor looks at a story and decides it's "too boring" and needs an attention-grabbing headline.
Nowhere in the original article does the author talk about the implications for life on Europa. It's just the UPI folks who tried to spice it up, and of course got it all wrong.
For the record, scientists have always known the radiation environment on the surface of Europa is very intense; but the assumption has always been that if there were life on Europa it would be buried many kilometers deep in the ocean, which acts as a shield.
Once again, I wish the skills of critical thinking and basic science were taught better in schools...
Or the other guy at NUWCDETNOR that, in the course of troubleshooting a problem with one of the fire control consoles on board one of the submarines, went through five $30,000 CRTs before one of the on-board techs stopped him?
Just out of curiosity, why is the military spending $30,000 on a cathode-ray tube? You can buy a decent TV at Frys for $100; and sure the milspec ones will be ruggedized etc. But come on , $30K !?
I've built spacecraft, and I thought the price premium was steep there... but apparently nothing compared to the military.
Shame, people. The comments so far have seemed to be limited to "Big deal. And he spent $1000. And his server got/. ed".
Think about it. He built an autonomous system that went almost to the edge of space, recorded images and temperature data, and came back. I can think of a bunch of simple, fun, experiments one could do. Cosmic rays, UV astronomy, ozone measurements, etc etc.
If he flies that thing again, I'd like to help out.
The space stuff is actually far too fragile to work on Earth, and is designed from a payload perspective to be light, not Earth-durable.
Uhm, no. There are several problems with the space environment, that all end up requiring very robust construction:
(1) The launch loads. The thing gets shaken up quite badly on launch (10's of G's around 100 Hz), not to mention acoustic loads around 200 dB.
(2) Pyro shock. A lot of propulsion system valves are one-shot explosively actuated, for reliability reasons. The effect of firing one is akin to hitting the spacecraft with a sledgehammer.
(3) Space radiation. Typical designs call for spacecraft to withstand doses of 20-100 kiloRad (a lethal dose is about 500 rad). This will fry your home computer!
(4) Thermal loads. As mentioned by others, the thermal environment is extreme, with swings from 10K in shadow to 300K in sunlight. Of course, the spacecraft is designed so the internals don't see such swings (so a computer can be in a warm box and stay at a comfortable 270 +/- 20K). But the swings can play hell with the exterior of the craft.
(5) Plasma and upper atmospheric effects. In particular atomic oxygen (in low Earth orbit) does nasty things to the spacecraft; in addition there can be problems with rocket and thruster exhaust (if the conductive plasma enters the electronics you can have your spacecraft die).
(6) General reliability. If you've spent a gigabuck on the thing you can't have it die because of one lousy component. So you have to design for extreme reliability - look at the Pioneers; still working after 30 years with no maintenance! It makes server reliability seem trivial by comparison.
So no, spacecraft have to be sturdy things. However, they are designed for a different environment - so they won't necessarily withstand e.g. saltwater immersion very well.
Your post was going so well... but then you had to bring up cold fusion. If it has been replicated, can you give references? And not just a google search, but preferably point to a properly peer-reviewed journal article.
And has that kept the U.S. military from firing people for being gay?
Yes. They got a lot of flak over that, prompting them to change the policy... I don't know the exact policy now, but according to my cousin in the marines, it's somewhere between "don't ask don't tell" and "just don't hit on the other soldiers".
Well, this tells a different story. However, you appear to have a point: according to this story the military is of two minds on the matter, in practice if not in policy. However, the point remains that you can get your life ruined when your privacy is violated, even if you aren't doing anything that you (?) or I would consider wrong. Here's another example , although I wish I could find a link to the original story.
This is getting offtopic, but it is interesting nonetheless. Going back to the issue of privacy
I think it boils down to very simple point: my life is my business. That may not always be true in practice, but then that is where legal protection is needed.
By the way, there is a blurb in AvWeek about the original topic:
The Defense Advanced Research Projects Agency's idea for a Total Information Awareness (TIA) system is stirring up a hornet's nest. It is one of 15 projects at Darpa's "information awareness office" aimed at using information technology to prevent and preempt terrorist attacks. The gist of TIA is to use signal processing similar to that used in anti-submarine warfare to ferret out the signature of terrorist transactions in cyberspace. But critics have huge concerns about civil liberties and privacy if the government starts mining all sorts of databases for information on civilian transactions. It doesn't help that the Darpa office is run by Vice Adm. (ret.) John Poindexter of Iran-Contra fame. Robert Popp, Poindexter's deputy, acknowledges that privacy will be a challenge. But at a forum at nearby George Mason University last week, Air Force Lt. Gen. Michael V. Hayden, director of the National Security Agency, which is responsible for all Defense Dept. sigint, said he doesn't understand how TIA would work or if it is feasible.
Because eventually they'd get to someone like me, who has nothing to hide.
But do you have nothing to lose?
It applies to the government, too. Everyone will be able to see exactly what the FBI and the CIA and the NSA are up to
How does this follow? Will the NSA publish their intercepts? No, open government is a great idea, but I doubt the U.S. government would open up voluntarily. If anything it has recently clamped down on information "because it might help terrorists".
I think our constitution needs another ammendment that says something along the lines of "No law shall be passed which denies an adult individual the right to perform an act which causes no harm to any individual other than the actor."
Good luck getting that through. After all there are states that still have sodomy laws on the books. And you want a constitutional amendment no less.
Fortunately, though, our first ammendment already covers the most important rights of all. As long as it stays intact and as well-defended as it is
The point is that you can, in practice, damage the first amendment without breaking it. All you need to do is make it clear to people that they may be free to speak up, but there will be consequences.
This is the famous "chilling effect". The problem is that the consequences can be serious, but subtle enough that most people not affected will simply not care. A perfect example is the new airline watch list: e.g. if you are caught protesting missile defense, or the "School of the Americas", you can look forward to a strip search every time you want to fly in the U.S. Sure, it may not deter the hardcore activists, but it will
help keep such opinions marginalized (there was an article in Salon.com recently but I can't find the link anymore).
I think a 100% open information society could have a lot of advantages.
This new government database is a long way from an open society. Your use of phrases like "information wants to be free" makes me think you understand that "knowledge is power". Now we have a case of the government collecting information; I don't think they should have the associated power, at least not without a helluva lot more oversight.
Companies who fire people for being gay are limiting their own selection of employees and making an unprofitable decision. Besides that, such actions tend to generate lots of negative publicity.
And has that kept the U.S. military from firing people for being gay?
I'm not trolling, but could someone please tell me what the "privacy concerns" surrounding this are?
Because knowledge is power, and power corrupts.
Seriously though, it's hard to give a short answer without using catch-phrases, but your question is reasonable, so here goes..
According to many people, the specific problem with the proposed new database and ID number is that it gives too much power to law enforcement and intelligence services. How? Well, the value of a database increases combinatorically with the amount of information (about a given individual) in it. At some point it really becomes possible to know almost everything about a person... And that is scary, because that means that most likely you can now intimidate or control them. What if they are gay? You can threaten to cost them their job (or life in some places of the country). What if they are looking at porn? You can threaten to ruin their marriage. What if they have an expensive health problem? You can cost them health insurance. Or you can just plain make stuff up about them - and once it is in the system there may be little they can do. Imagine not being able to buy a car or a house because you can't get credit - because the computer says you are not credit-worthy. Or if you want to work at an aerospace company but can't get a job because you "aren't cleared". There is often very little you can do to clean up your reputation (If you've ever been a victim of identify theft you know what I'm talking about). The point is that it doesn't take much - maybe you don't go to jail, but your life gets hard enough that you stop worrying about improving government and just hunker down trying to keep a job.
Another example; the library may have a list of your reading habits, your ISP knows what you look at on the Web, and the credit card company knows what you purchase... Now, what if the government had easy access to all of the above? The point being "easy" as in they can go fishing (or data mining) for "suspicious" behaviour - as opposed to having to obtain a warrant for a specific individual based on probable cause.
This gets very interesting when you start compiling "watch lists", where certain people are singled out for attention. The recent airline security lists are a perfect example - they are apparently being used to harass peace activists, left-leaning activists etc etc. It really doesn't take much to have a chilling effect on political freedom. You may be able to shout your political opinions on the street corner thanks to the first amendment, but if it means that you'll be strip searched every time you travel, you may prefer to keep a lower profile. And that's all those in power want - for the opposition to just fade away.
The most serious problem is that it circumvents any checks and balances to the abuse of power. Imagine if the FBI started compiling files on the political opposition, and used blackmail to silence them? This is illegal (not to mention bad for the country because it destroys democracy). The courts should step in, right? Well, what if the FBI started compiling information on judges, and used that to keep the courts in line? Maybe some good investigative journalists will blow the whole thing open - or maybe they can be blackmailed too...(or nowadays the parent company can be convinced to shed "unprofitable" investigative reporting). You may think this will never happen, but do you really want to put that kind of power in the hands of a small group of people, with no insight into what they use it for? In case you don't know your history, look up Hoover and the FBI. Or read about the STASI in East Germany, and how to control a society using a primitive version of this kind of database. There it was sometimes possible to break up political protests by merely taking pictures of the demonstrators - they all knew what the consequences would be if they were identified.
I think history shows us that government works best when its powers are strictly limited. This past year has seen a tremendous increase in government power; it remains to be seen what will happen, but past experience isn't comforting.
Who says the universe works in numbers? Why do we think that we can bring everything down to math. Maybe it cant be done and we are not exactly wasting time but we wont ever find the end if we simply exploit math.
Because it has worked pretty well for us so far. Come up with something better and scientists will use it. In the mean time, why not continue along a line of progess that has a tremendous history of success?
I personally won't put a 1/4 watt next to my head on a daily basis.
And yet how many hours each day do you spend staring at your monitor?
Sigh. This is why I wish they would do a better job teaching physics in high school...
How about the roughly 10-20 W of sunlight falling on your head during a typical sunny day? Or the couple of watts from a typical room light? What about the sound energy in your stereo headphones?
Or the energy deposited in your head by the cluestick I'm trying to wield?
"Watts" is not the right unit when you are trying to estimate biological risk - it's a unit of power. At the very least you need to take into account the total amount of energy involved, and
just as importantly, the energy level of the photons involved. A Joule of gamma rays (1 W for 1 second of energy with a charcteristic wavelength of 10^-11 m) will do a helluva lot more biological damage than a Joule of microwaves (1 cm wavelength). This is because the microwave radiation (emitted by cell phones) don't have enough energy to ionize the atoms in your brain. They can jiggle them around and thus warm them up,
but there is a big difference between warming your brain up by 0.001 degrees and disrupting a few million base pairs in your DNA.
I don't understand why NASA does not employ lead shielding to protect its astronauts.
Fair question, but one with a fairly simple answer.
Lets do some numbers...
To within a factor of a few, what matters in radiation shielding is "surface density", i.e. how many grams of material per square centimeter there are in your shield. So you can have a thick shield of light material, or a thin shield of dense material; for the same area they will provide the same shielding effect if they have the same mass.
Say for a moment that you want as much shielding as provided by the Earths atmosphere; that works out to be about 10 tons/square meter. (If you SCUBA dive: remember that the pressure goes up by 1 atmosphere for every 10 meters of depth. A 10x 1x1 meter column of water weighs 10 tons.)
Those ten tons/m2 can be in any form you want: a
10 km thick air shield, 10 meters of ice, 2 meters of rock, or a meter of lead.
So, you want to put a couple of guys in a spaceship and send them to Mars? Well, put them in a cramped tube, say 10 meters long and 3 meters in diameter. That gives you about 100 square meters of surface area.... or 1000 tons of shielding.
At current prices it costs about $20,000 to put a kilogram of material into low Earth orbit. The biggest rocket flown to date can put about 100 tons into orbit. With current technology you either hit up Bill Gates for the 20 billion, or you can skimp on the shielding. The space
station skimps by a factor of 300 (you get a years ' worth of background radiation in a single day).
You could also play games like have most of the spacecraft lightly shielded, but have a lead-lined "storm shelter" for the times when solar flares erupt. This works because much of the radiation comes in bursts. However, it isn't useful for going to places with continuous high levels of radiation, like Jupiter.
That's why we need a new and cheaper space launch system.
If you use distance, there are two possible solutions... You're thinking direction.
The physics are right here...
on
The Coming Air Age
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· Score: 2, Insightful
Remember that the kinetic energy involved in flying is a lot greater than for most cars; even a Cessna is doing 150-200 mph, while few cars are doing that during the morning commute. That makes any collision much more dangerous, be it with the ground or with other planes/cars. I suspect that death/injury rates are similar for general aviation and racing cars, since the speeds are similar.
So if we ever see widspread personal flying, I wouldn't be surprised if it was using some form of ultra-light, with speeds in the 50-100 mph range.
As for personal helicopters - the things are hell to maintain. I know people who think getting a tune-up at 100,000 miles is a pain. Imagine trying to fly a chopper for ten years with no maintenance...
An important additional point that is getting missied is this: if anyone intercepts the message
it is immediately obvious to the intended recipient. In effect, by intercepting the signal the snooper corrupts the signal, so the intended recipient will not get an intelligble message. So this is even better than a one-time pad...
Of course, if there is something we don't yet know about quantum mech then perhaps it's not perfectly safe. Also, actually achieving 100% secure communication requires care in implementing the design - you can't put too many photons out there or some of them can be intercepted without tipping off the recipient.
So, a hard question is raised: How do you allow these pharmaceutical companies to compete in such a tough environment against competitors that have no costs
Acting as a free-market theologian here for a minute: If the competitors can do it better and at lower cost, why shouldn't they be allowed to "win"?
As for your first paragraph, if competitors can quickly produce analogues, why should they be stopped using patents? Because no one will bother to innovate, you say... But isn't that what e.g. the universities are for? After all, in my experience a lot more innovation comes from an open environment where people can build on each others' discoveries rather than run around trying to obfuscate/hide their progress for fear of being scooped...
It's not really all that different from the closed source vs open source argument. It's clear that the "open source" works best in basic science, and I think most Slashdotters think it works best in software, too. Why wouldn't it work in biomedical research?
Incidentally, why not just give a patient a complete blood transfusion to severely dilute the aids virus, then hit it with the cocktail to kill anything else off? Is this too simplistic?
Unfortunately it isn't that easy. IANABC, but a friend of mine is doing an M.D./PhD working on AIDS. He tells me that the virus hides away copies of itself in all sorts of cells (immune cells, nerve tissue). That's apparently why it is proving impossible to completly eradicate it using the drug cocktails. Despite the occasional mircale story, most of those who have HIV and stop taking the drugs have the virus re-appear.
In the words of my friend, "it's an evil little bug".
Well, possibly. SOFIA which is an airborne observatory expects to get 2-4 arcsecond seeing at 40,000 ft. If the JSF laser does something similar then yes, the beam spread will be small enough to not be a problem.
They'll just have to manage the boundary layer carefully..
But the turbulence in the atmosphere between the plane and the target.... i.e. the same stuff that makes the stars twinkle. It'll disrupt the beam and spread it out,
likely by enough to make the beam more or less harmless, unless corrected. And doing that correction is very hard.
These clowns never mentioned that the "adaptive optics" they want to use to keep the beam focused
are very experimental (in this application). I have worked with the stuff, and it is ok for astronomy - but actually focusing a laser in the sort of environment the JSF will be in (low altitude, high-G forces, turbulent flow across the aircraft skin) strikes me as really hard.
I'd say we should wait and see how the ABL performs before getting rid of the trusty ol' AMRAAM.
Slashdot Mirror
Uh, no. Replace socialism with fascism and I might agree with your comment. But you've obviously never lived in a socialist country.
It's amazing how much radiation certain bacteria can survive, though..
By the way, NASA is thinking about a new mission to the Galilean moons, called JIMO . Very exciting stuff - it's amazing how much more you can do with a nuclear propulsion stage.
Nowhere in the original article does the author talk about the implications for life on Europa. It's just the UPI folks who tried to spice it up, and of course got it all wrong.
For the record, scientists have always known the radiation environment on the surface of Europa is very intense; but the assumption has always been that if there were life on Europa it would be buried many kilometers deep in the ocean, which acts as a shield.
Once again, I wish the skills of critical thinking and basic science were taught better in schools...
So would I...
.
Just out of curiosity, why is the military spending $30,000 on a cathode-ray tube? You can buy a decent TV at Frys for $100; and sure the milspec ones will be ruggedized etc. But come on , $30K !? I've built spacecraft, and I thought the price premium was steep there... but apparently nothing compared to the military.
Radioisotope thermal generators - a favorite of the space program. The Soviets apparently used them for navigation buoys and similar...
Just imagine the reaction from people who object to bulldozing ice when you mention RTGs.. :)
Think about it. He built an autonomous system that went almost to the edge of space, recorded images and temperature data, and came back. I can think of a bunch of simple, fun, experiments one could do. Cosmic rays, UV astronomy, ozone measurements, etc etc.
If he flies that thing again, I'd like to help out.
Uhm, no. There are several problems with the space environment, that all end up requiring very robust construction:
(1) The launch loads. The thing gets shaken up quite badly on launch (10's of G's around 100 Hz), not to mention acoustic loads around 200 dB.
(2) Pyro shock. A lot of propulsion system valves are one-shot explosively actuated, for reliability reasons. The effect of firing one is akin to hitting the spacecraft with a sledgehammer.
(3) Space radiation. Typical designs call for spacecraft to withstand doses of 20-100 kiloRad (a lethal dose is about 500 rad). This will fry your home computer!
(4) Thermal loads. As mentioned by others, the thermal environment is extreme, with swings from 10K in shadow to 300K in sunlight. Of course, the spacecraft is designed so the internals don't see such swings (so a computer can be in a warm box and stay at a comfortable 270 +/- 20K). But the swings can play hell with the exterior of the craft.
(5) Plasma and upper atmospheric effects. In particular atomic oxygen (in low Earth orbit) does nasty things to the spacecraft; in addition there can be problems with rocket and thruster exhaust (if the conductive plasma enters the electronics you can have your spacecraft die).
(6) General reliability. If you've spent a gigabuck on the thing you can't have it die because of one lousy component. So you have to design for extreme reliability - look at the Pioneers; still working after 30 years with no maintenance! It makes server reliability seem trivial by comparison.
So no, spacecraft have to be sturdy things. However, they are designed for a different environment - so they won't necessarily withstand e.g. saltwater immersion very well.
Yes. They got a lot of flak over that, prompting them to change the policy... I don't know the exact policy now, but according to my cousin in the marines, it's somewhere between "don't ask don't tell" and "just don't hit on the other soldiers".
Well, this tells a different story. However, you appear to have a point: according to this story the military is of two minds on the matter, in practice if not in policy. However, the point remains that you can get your life ruined when your privacy is violated, even if you aren't doing anything that you (?) or I would consider wrong. Here's another example , although I wish I could find a link to the original story.
This is getting offtopic, but it is interesting nonetheless. Going back to the issue of privacy I think it boils down to very simple point: my life is my business. That may not always be true in practice, but then that is where legal protection is needed.
By the way, there is a blurb in AvWeek about the original topic:
The Defense Advanced Research Projects Agency's idea for a Total Information Awareness (TIA) system is stirring up a hornet's nest. It is one of 15 projects at Darpa's "information awareness office" aimed at using information technology to prevent and preempt terrorist attacks. The gist of TIA is to use signal processing similar to that used in anti-submarine warfare to ferret out the signature of terrorist transactions in cyberspace. But critics have huge concerns about civil liberties and privacy if the government starts mining all sorts of databases for information on civilian transactions. It doesn't help that the Darpa office is run by Vice Adm. (ret.) John Poindexter of Iran-Contra fame. Robert Popp, Poindexter's deputy, acknowledges that privacy will be a challenge. But at a forum at nearby George Mason University last week, Air Force Lt. Gen. Michael V. Hayden, director of the National Security Agency, which is responsible for all Defense Dept. sigint, said he doesn't understand how TIA would work or if it is feasible.
The FBI is on occasion not above a little blackmail (especially the 3rd paragraph) They also like to keep tabs on the political opposition.
Seriously. You're paranoid...
No, just cynical. You're naive.
Because eventually they'd get to someone like me, who has nothing to hide.
But do you have nothing to lose?
It applies to the government, too. Everyone will be able to see exactly what the FBI and the CIA and the NSA are up to
How does this follow? Will the NSA publish their intercepts? No, open government is a great idea, but I doubt the U.S. government would open up voluntarily. If anything it has recently clamped down on information "because it might help terrorists".
I think our constitution needs another ammendment that says something along the lines of "No law shall be passed which denies an adult individual the right to perform an act which causes no harm to any individual other than the actor."
Good luck getting that through. After all there are states that still have sodomy laws on the books. And you want a constitutional amendment no less.
Fortunately, though, our first ammendment already covers the most important rights of all. As long as it stays intact and as well-defended as it is
The point is that you can, in practice, damage the first amendment without breaking it. All you need to do is make it clear to people that they may be free to speak up, but there will be consequences. This is the famous "chilling effect". The problem is that the consequences can be serious, but subtle enough that most people not affected will simply not care. A perfect example is the new airline watch list: e.g. if you are caught protesting missile defense, or the "School of the Americas", you can look forward to a strip search every time you want to fly in the U.S. Sure, it may not deter the hardcore activists, but it will help keep such opinions marginalized (there was an article in Salon.com recently but I can't find the link anymore).
I think a 100% open information society could have a lot of advantages.
This new government database is a long way from an open society. Your use of phrases like "information wants to be free" makes me think you understand that "knowledge is power". Now we have a case of the government collecting information; I don't think they should have the associated power, at least not without a helluva lot more oversight.
Companies who fire people for being gay are limiting their own selection of employees and making an unprofitable decision. Besides that, such actions tend to generate lots of negative publicity.
And has that kept the U.S. military from firing people for being gay?
Because knowledge is power, and power corrupts.
Seriously though, it's hard to give a short answer without using catch-phrases, but your question is reasonable, so here goes..
According to many people, the specific problem with the proposed new database and ID number is that it gives too much power to law enforcement and intelligence services. How? Well, the value of a database increases combinatorically with the amount of information (about a given individual) in it. At some point it really becomes possible to know almost everything about a person... And that is scary, because that means that most likely you can now intimidate or control them. What if they are gay? You can threaten to cost them their job (or life in some places of the country). What if they are looking at porn? You can threaten to ruin their marriage. What if they have an expensive health problem? You can cost them health insurance. Or you can just plain make stuff up about them - and once it is in the system there may be little they can do. Imagine not being able to buy a car or a house because you can't get credit - because the computer says you are not credit-worthy. Or if you want to work at an aerospace company but can't get a job because you "aren't cleared". There is often very little you can do to clean up your reputation (If you've ever been a victim of identify theft you know what I'm talking about). The point is that it doesn't take much - maybe you don't go to jail, but your life gets hard enough that you stop worrying about improving government and just hunker down trying to keep a job.
Another example; the library may have a list of your reading habits, your ISP knows what you look at on the Web, and the credit card company knows what you purchase... Now, what if the government had easy access to all of the above? The point being "easy" as in they can go fishing (or data mining) for "suspicious" behaviour - as opposed to having to obtain a warrant for a specific individual based on probable cause.
This gets very interesting when you start compiling "watch lists", where certain people are singled out for attention. The recent airline security lists are a perfect example - they are apparently being used to harass peace activists, left-leaning activists etc etc. It really doesn't take much to have a chilling effect on political freedom. You may be able to shout your political opinions on the street corner thanks to the first amendment, but if it means that you'll be strip searched every time you travel, you may prefer to keep a lower profile. And that's all those in power want - for the opposition to just fade away.
The most serious problem is that it circumvents any checks and balances to the abuse of power. Imagine if the FBI started compiling files on the political opposition, and used blackmail to silence them? This is illegal (not to mention bad for the country because it destroys democracy). The courts should step in, right? Well, what if the FBI started compiling information on judges, and used that to keep the courts in line? Maybe some good investigative journalists will blow the whole thing open - or maybe they can be blackmailed too...(or nowadays the parent company can be convinced to shed "unprofitable" investigative reporting). You may think this will never happen, but do you really want to put that kind of power in the hands of a small group of people, with no insight into what they use it for? In case you don't know your history, look up Hoover and the FBI. Or read about the STASI in East Germany, and how to control a society using a primitive version of this kind of database. There it was sometimes possible to break up political protests by merely taking pictures of the demonstrators - they all knew what the consequences would be if they were identified.
I think history shows us that government works best when its powers are strictly limited. This past year has seen a tremendous increase in government power; it remains to be seen what will happen, but past experience isn't comforting.
Because it has worked pretty well for us so far. Come up with something better and scientists will use it. In the mean time, why not continue along a line of progess that has a tremendous history of success?
And yet how many hours each day do you spend staring at your monitor?
Sigh. This is why I wish they would do a better job teaching physics in high school...
How about the roughly 10-20 W of sunlight falling on your head during a typical sunny day? Or the couple of watts from a typical room light? What about the sound energy in your stereo headphones? Or the energy deposited in your head by the cluestick I'm trying to wield?
"Watts" is not the right unit when you are trying to estimate biological risk - it's a unit of power. At the very least you need to take into account the total amount of energy involved, and just as importantly, the energy level of the photons involved. A Joule of gamma rays (1 W for 1 second of energy with a charcteristic wavelength of 10^-11 m) will do a helluva lot more biological damage than a Joule of microwaves (1 cm wavelength). This is because the microwave radiation (emitted by cell phones) don't have enough energy to ionize the atoms in your brain. They can jiggle them around and thus warm them up, but there is a big difference between warming your brain up by 0.001 degrees and disrupting a few million base pairs in your DNA.
Fair question, but one with a fairly simple answer. Lets do some numbers...
To within a factor of a few, what matters in radiation shielding is "surface density", i.e. how many grams of material per square centimeter there are in your shield. So you can have a thick shield of light material, or a thin shield of dense material; for the same area they will provide the same shielding effect if they have the same mass.
Say for a moment that you want as much shielding as provided by the Earths atmosphere; that works out to be about 10 tons/square meter. (If you SCUBA dive: remember that the pressure goes up by 1 atmosphere for every 10 meters of depth. A 10x 1x1 meter column of water weighs 10 tons.) Those ten tons/m2 can be in any form you want: a 10 km thick air shield, 10 meters of ice, 2 meters of rock, or a meter of lead.
So, you want to put a couple of guys in a spaceship and send them to Mars? Well, put them in a cramped tube, say 10 meters long and 3 meters in diameter. That gives you about 100 square meters of surface area.... or 1000 tons of shielding.
At current prices it costs about $20,000 to put a kilogram of material into low Earth orbit. The biggest rocket flown to date can put about 100 tons into orbit. With current technology you either hit up Bill Gates for the 20 billion, or you can skimp on the shielding. The space station skimps by a factor of 300 (you get a years ' worth of background radiation in a single day). You could also play games like have most of the spacecraft lightly shielded, but have a lead-lined "storm shelter" for the times when solar flares erupt. This works because much of the radiation comes in bursts. However, it isn't useful for going to places with continuous high levels of radiation, like Jupiter.
That's why we need a new and cheaper space launch system.
So if we ever see widspread personal flying, I wouldn't be surprised if it was using some form of ultra-light, with speeds in the 50-100 mph range.
As for personal helicopters - the things are hell to maintain. I know people who think getting a tune-up at 100,000 miles is a pain. Imagine trying to fly a chopper for ten years with no maintenance...
Of course, if there is something we don't yet know about quantum mech then perhaps it's not perfectly safe. Also, actually achieving 100% secure communication requires care in implementing the design - you can't put too many photons out there or some of them can be intercepted without tipping off the recipient.
Acting as a free-market theologian here for a minute: If the competitors can do it better and at lower cost, why shouldn't they be allowed to "win"?
As for your first paragraph, if competitors can quickly produce analogues, why should they be stopped using patents? Because no one will bother to innovate, you say... But isn't that what e.g. the universities are for? After all, in my experience a lot more innovation comes from an open environment where people can build on each others' discoveries rather than run around trying to obfuscate/hide their progress for fear of being scooped... It's not really all that different from the closed source vs open source argument. It's clear that the "open source" works best in basic science, and I think most Slashdotters think it works best in software, too. Why wouldn't it work in biomedical research?
Unfortunately it isn't that easy. IANABC, but a friend of mine is doing an M.D./PhD working on AIDS. He tells me that the virus hides away copies of itself in all sorts of cells (immune cells, nerve tissue). That's apparently why it is proving impossible to completly eradicate it using the drug cocktails. Despite the occasional mircale story, most of those who have HIV and stop taking the drugs have the virus re-appear. In the words of my friend, "it's an evil little bug".
I'd say we should wait and see how the ABL performs before getting rid of the trusty ol' AMRAAM.