As what? A janitor? No scientist would make comments like that, because a real scientist knows how unpredictable this sort of work is.
Yes, as a scientist. I'd be happy to compare degrees with you anyday, Mr. Anonymous Jackass. A real scientist also knows how important public support is; without public enthusiasm, there will be no more 3-billion dollar missions.
The Mars rovers did "real science", and they had a PR operation that blows ESA out of the water.
Am I the only one who thinks ESA has completely dropped the ball here? They string us out all day, and in the end all they show is ONE stinking picture? They say they have 300+. Why not share even just a few with the public? I used to work at JPL, and let me tell you, when the landers hit the ground, we had a serious PR effort up and running right away. These guys are acting like they own the data and we'll have to wait for the research papers to be published before we get to see the images.
A few years ago I was working on a NASA project - nothing secret. We had a Canadian summer student come and work for us on a small job (writing some code to control some optics). As a foreign national he had to get clearance, but he was allowed to start working on writing some code for the project while we waited. Six weeks later his application was rejected and he was no longer allowed to touch any of our computers, or look at any code, including the code he'd written himself. Now he works for a European project doing the same sort of stuff, and I know they are very happy to have him. Stupid, short-sighted xenophobic policies like that do nothing but hurt this country.
I think the problem with this kind of stuff is that it's the people who are valuable, not the ideas. Policies that try to lock down ideas just drive away good people.
Why do we Americans always seem to assume that we're somehow that much smarter than everyone else, and if we keep our research secret then the Chinese, or Indians, or God forbid, the Canadians won't figure it out on their own? Somehow we have a situation where the security folks (who it seems are all all-American white boys from Texas) write policies to prevent the scientists (who are to a surprising extent foreign immigrants) from actually getting anything done. Of course, in the end, it's the scientists who come up with the technology to keep the secirity guys (and their families) safe. That's just too complicated for these dumb white boys to grasp, I guess.
When it comes to basic research, it's amazing how even seemingly trivial impediments to access and communication can utterly inhibit progress. Sure, it's only a biometric card, but the additional hassle will mean that you are that much less likely to hire say, that Polish kid who just happens to actually have a good education in math.
Given that U.S. high schools just aren't producing kids that know math, that's a real problem. And yes, I know I do most of my useful work late at night and on weekends, so inhibiting access on non-standard hours is a real pain.
My most fundamental objection to all this though, is simply that I don't WANT to live in a society where Big Brother constantly monitors my every move, knows what my retina looks like, keeps track of who I meet and what I read, what I say, and
how I spend my money. I understand that access control to military research might be needed, and that's why I don't do military work. But when they want civilian researchers (like NASA) to follow suit, then I don't have any choice. And I hate that.
I've heard people talk about He-3 forever, but
I have never once seen anything remotely like
hard numbers showing the concentration of He-3 on the lunar surface.
I'd be extremely skeptical of this until someone shows some real discussion (i.e. not just puff-pieces on space.com) as to why this is feasible. Anyone? Of course, you also have to show that fusion using He-3 can be done (it's harder than D-T fusion, which we still haven't mastered, I might add).
Other people have proposed "Alternative Three: Replace Hubble with ground telescopes".
I am an astronomer, and I've worked on AO systems, and I can tell you that I'd rather have Hubble than all the AO-corrected Kecks in the world. AO sounds like a good idea, but in the end the data you get out is hard to calibrate, and unreliable. The problem is that the properties of the atmospheric turbulence keep changing, making it hard for the AO to keep up. The best AO-systems available today achieve maybe 70% of the performance of a diffraction limited system such as a telescope in space. But the remaining 30% of the light goes into a big "halo" that has all sorts of complicated image structure in it.
Then there is the fact that the field of view that you get with an AO system is much, much smaller that you'd get with Hubble. And then there are issues with higher thermal background, etc. A while back HST published a light-curve of an eclipsing extra-solar planet - something like that could never be done from the ground (i.e. with the same precision).
The University of Arizona's $120 million Large Binocular Telescope is the world's most powerful optical telescope, with images about 10 times as sharp as the Hubble's.
No, not really. LBT will not produce sharp images in the visible, at least not with any AO system that one could build today. In the near-Infrared LBT will still be subject to all the disadvantages inherent in AO systems, and in addition will have the problems associated with interferometry, since it is actually two telescopes cobbled together to act as one. LBT will, if it ever works, and press-releases notwithstanding, not be
quite the Hubble-killer it's sometimes made out to be.
It's not just about the Kyoto treaty - the treaty itself would have a rather limited impact, though would be a good first step. The reason the rest of the world (and half of the U.S. voters) dislike the Bush attitude is that it is basically an attitude of "Me first. Screw the rest of the world."
Bush seems to think that a) there are no global-scale problems, b) even if there were, they should not be solved through collective action and c) the U.S. has a divine right to screw the rest of the world, take their resources, install oppressive regimes, etc etc.
The rest of the world doesn't like getting screwed. And half of the U.S. voters are smart enough and civilised enough to realize that sometimes co-operation is the better way.
But it doesn't matter - the world isn't a democracy, and as we know, a few idiots in the "heartland" have taken all the world along for a demonstration of what happens when you let Enron-style capitalism and religious fundamentalism run things.
The good news is that now we'll all find out who is right. Are those who warn of the dire consequences of unilateralism, pre-emptive war, environmental destruction etc etc. just being whiny, or not? Maybe global warming really is just a conspiracy among scientists who want attention and funding. Maybe freedom and U.S.-style free markets will bloom in Iraq, and be so wonderful that the Palestinians will realize that they should strop trying to get back their land and go get a job for McDonalds. Maybe the "expert" opinions of the NAS, or the U.N., or our oldest allies, are just plain wrong, and reality will yield to faith.
I'm rather curious, actually. It's not every day that you get a chance to see your beliefs put to the test. Besides, it'll be fun - kinda like watching NASCAR; it's more fun when you think there will be a wreck.
It's a reasonable paraphrase of some of the assertions in Thomas Kuhn's 'The Structure of Scientific Revolutions" which is the backbone (along with Popper's ideas and some french folks' theories) of modern conceptions of science and how science changes.
I would argue that most physical scientists will disagree with much of what is claimed by "philosphers of science". Violently, or at least vehemently, in the case of the "French folks" you mentioned - see the Sokal affair.
"This phenomenon could generate a dramatic revolution in technology, which would result from a dramatic paradigm shift in science. Anomalies are the key to all paradigm shifts"
This illustrates a classic logic problem: though perhaps all advances come from "anomalies", not all anomalies imply advances. Or put another way, Einstein may have been thought a cook, but that does not imply that all cooks are Einsteins. (Of course, not even Einstein was thought to be a cook - his theory very quickly was accepted).
they need to cover the costs of development and to underwrite further research.
As you've no doubt been told a million times by now, the cost of research is dwarfed by the advertising budgets. This is because company execs have figured out that a dollar spent advertising a drug you already have for a new disease returns at least twice as much as that same dollar spent trying to develop new drugs. That's why heartburn became "acid reflux disease".
The big, dark secret of the drug industry is that they just aren't very good at finding cures. I could name more than one large company with empty pipelines... This despite the fact that they receive what is in effect an enormous subsidy in the form of government-funded basic research. Part of the problem is that the for-profit modus operandi of "patent everything and let the lawyers sort it out" actually does more to stifle science than it does to stimulate it. Sure, there are now many companies that make their money selling licenced lab products and techniques to drug developers, but this just means that a lot of effort gets wasted in a) trying to do your science without infringing on 50 different patents, or b) raising funds so you can actually afford to pay for the one crucial step that would take 30 minutes in the lab with a heat-block and some enzyme.
Kerry just strikes you as a used car salesman, lying strait to your face with a smile (not saying he is, but he gives that impression)
Can you please give an example? If not, and you seem to back off from your charge, why do you base your opinion on an impression that you admit is false?
That just makes no sense to me.
Personally I started out luke-warm towards Kerry, but the more I hear him speak the more I realize that a) the man is very intelligent and knowledgeable, b) the man thinks very deeply about issues in front of him, c) he did a good job leading and taking care of his crew in the Mekong delta, and d) he volunteered to risk his life out of a sense of duty to his nation. That has to speak to his character.
The more I see Bush the more I realize that he's just plain out of his depth. He doesn't belong anywhere near the big red button.
btw, can anyone can tell me what makes GW so much worse than other past presidents? Just as some examples, I think his dad was MUCH worse by pulling out of Iraq,
41 was smart enough to realize what a disaster he'd have on his hands if he took Baghdad; the U.S. wasn't and isn't prepared to deal with the aftermath of destroying a country like Iraq. That should be obvious by now.
and John F Kennedy nearly annihilated the entire planet because he wouldn't just make a deal with the russians (sure it would be a small sign of weakness, but jesus christ, the alternative is crazy).
Where do you get the quaint notion that Kennedy didn't make a deal? At the time of the crisis we had 25 Jupiter missiles stationed in Turkey, a threat that nicely mirrored placing missles in Cuba. Within six months of the crisis those missiles had been decommissioned, ostensibly because they were no longer needed. But we did not have our first wing of Minuteman I missiles fully operational for a couple years after that, so I'm not sure that argument holds.
Yes, that is what a Hohlraum is. The point being that inside the cavity the radiation field is uniform.
In the case of a thermonuclear weapon, the problem is how to uniformly compress the fusion fuel until it ignites. You can't achieve the necessary uniformity using multiple explosions. However, if you enclose the fusion fuel and the fission trigger inside a large cavity, the X-rays emitted by the fission trigger will be trapped in the cavity (for a few microseconds) long enough to come to equilibrium. This radiation field then puts uniform pressure on every surface inside the Hohlraum, including the fusion fuel, thus compressing it.
This is the Teller-Ulam process, and it was officially classified until the 70's or 80's. Of course, like all great ideas it's a fairly obvious one (every major nuclear power discovered it independently), and so the classification was kind of silly. Not that that stopped the various governments from trying to keep it a secret - of course the existence of fusion weapons wasn't secret, so there was a bit of mis-direction put out there, in particular the idea that compression was achieved by surrounding the fuel with multiple fission triggers.
Actually the scary part is how much they don't know but still manage to come off sounding like they do to some slashdot moderators.
Out of curiosity, what did I get wrong in my post? I really am curious; nukes have been a long-standing interest of mine (geek that I am), and though I am not a weapons-physicist, I am trained as a physicist and have talked a fair amount with folks who built bombs (I took a couple of physics classes from a guy who used work on bombs - one of the most memorable times was when he explained in detail how the castle Bravo test gave a much larger yield than predicted. I'm glad that I work in a field where if I make a miscalculation the worst that happens is a delayed research paper, not 6 extra megatons of explosive yield.
A thermonuclear bomb (at least as made in the fifties) is essentially a tank of deuterated and tritiated lithium hydride (LiH) that will explode with great fury if quickly raised to a temperature of millions of degrees within a span of milliseconds. It's very difficult to create the required temperatures quickly with chemical explosives- the easiest way to do it is to surround the tank with numerous small fission devices, which heat the tank to millions of degrees quickly and easily and are responsible for the radioactive fallout still associated with fusion bombs.
Close, very close, but not quite right. The trigger is a single fission bomb; the radiation it produces is redirected cleverly so as to compress the fusion charge (a concept referred to as a "Hohlraum"). In some designs there are more than two "stages" where fission triggers fusion, which then is used to trigger more fission or, in some cases, another fusion stage (the Soviet "Tsar Bomba" was a multistage fusion device of 60-120 Mtons. Check out the Nuclear Weapons FAQ for more info.
The "neutron bomb" was a planned attempt to replace the fission warheads with chemical explosives, creating a thermonuclear explosion with no radioactive fallout- a truly impressive feat if it were possible.
Not the neutron bomb I'm familiar with. It was a very low-yield fission-triggered device that had a fusion stage. There has long been a dream at LLNL to figure out how to initiate fusion with a conventional high-explosive trigger, but to my knowledge, no such weapon has ever been tested or fielded. The neutron bomb of the 80's would have created plenty of fallout and radioactivity; the point was it created less blast damage and so didn't sound as bad (the fallout was sort-of ignored).
He is talking about the tritiated lithium hydride,....Since the bomb was lost 46 years ago, which is about 4 tritium half lives, the maximum possible yield has in theory been reduced to 1/16 of what it was in 1958, and the actual yield is probably zero.
I think there is a small mis-understanding here. A fusion weapon of this type uses tritium to boost the yield of the fission trigger, NOT as a component in the fusion main stage fuel.
The fusion stage creates the tritum needed at the time of explosion by neutron-spallation of the Lithium. So, after 4 half-lives the fission trigger yield will be greatly reduced - probably enough to prevent any significant second-stage fusion. This means that if it exploded, the yield would be in the 10-kiloton range, not the megaton range. However, if the fusion stage were to ignite, it would do so with as much yield as ever.
Exponential progress has by no means stopped! Sure, we don't have craft traveling at the speed of light, but just because outward 1950's expectations haven't been met doesn't mean that the overall trend isn't still exponential- it is. Most of the progress has simply been focused inward, on communication, chips, biotech, and the all important nanotech.
That's rather arguable. I will agree that computers have progressed rapidly, though not in the way many SciFi authors thought (i.e. no artificial intelligence).
But nanotech? I can't think of any significasnt breakthrough in nanotech...
is why they are hot-rodding the vehicle.
I saw mention that the increased burn time would allow SpaceShipOne to achieve higher speed at lower altitude "where the control surfaces can bite into the air"; this tells me they are working to fix the near-disaster they had on the last flight. It sounds like they have no control authority outside the atmosphere - i.e. that whatever reaction-jet system they have isn't working well, and they are having to
jury-rig a fix. Increasing the impulse of a rocket by 20% (which is what they are doing) is a significant, and risky, change. They wouldn't be doing it unless they had to.
Could this cloud have been the result of a U.S. strike against a North Korean nuclear facility?
Maybe we located the place where they keep all of their bombs and just took it out?
#end tinfoilmode
I know, I can think of a million reasons why we shouldn't do something like that, but maybe we did anyway. It's not like this administration is beyond acting like cowboys...
A guy I know who worked at the Forsmark nuclear plant in Sweden told me that back in 1986, they found out about the Chernobyl accident way before anyone in the Swedish government.
I've actually worked there, and I remember that day. Now I really wish I hadn't spent a good part of that day outside in the rain. For years afterward there was a bit of a "hotspot" just north of Stockholm where that rainstorm had washed a bunch of stuff out of the cloud and onto the ground.
As for the possibility of civilians detecting a nuclear test - that depends on a lot of variables
such as how the wind blows. Given the geography of the location, the cloud might go out over open ocean or over China, in which case you won't hear anything from civilians. Or it could blow over Japan, in which case some university scientists might notice something.
Certainly the U.S. knows if it was a nuke thanks to our satellite systems; but the current regime may not wish to publicise such a failure of their anti-proliferation policy just before an election.
In any case, I would have thought that the North Koreans would make an announcement if they had actually had a successful test. Why wouldn't they?
I know they certainly trumpeted up their attempts at a space launch.
Remember, many of the writers and readers of SciFi grew up in an age of tremendous progress; in 50 years we went from no airplanes at all to super-sonic flight, and twenty years after that we'd gone to the moon. At the time, it seemed perfectly plausible that by 2001 there would be manned missions to Saturn. They lived in an age of exponential progress, and it was exciting. Of course it made for good story material.
Then things just stopped. We never went back to the Moon. The Concorde stopped flying. We no long dream of flying higher, faster, better.
The Shuttles blew up or were lost, space exploration was curtailed.
Sure, there has been much progress in the area of computers, but not as much as hoped (Hal 9000 anyone?). And the progress there is just makes Orwell look more prescient than, say, Heinlein or Clarke. The future we have isn't so exciting, and certainly isn't worth writing much about. At least not if your aim is to excite young kids about adventure, science and exploration.
It's a matter of frontiers - before SciFI there were Westerns; different setting, same basic idea.
SciFi will come back if we ever enter a new age of exponential progress in exploration. Until then, the stories will be escapist fantasy...
This is a great solution. Bosnia, Kosovo, Afghanistan, and Iraq would have benefited greatly from this.
Are you trolling, or just crazy? I bet the Taliban or the "insurgents" in Fallujah would love to be able to lob mortar rounds at real, live nuke plant. Not to mention if they got luck and managed to steal some nuclear material...
With all due respect to the above journals, they are not peer-reviewed journals where research results are reported. If the journals had been Nature, Science and Physics Review, then I'd be excited. But they aren't, so I'm not. Besides, I read the articles, and I didn't get the impression they were all that enthusiastic...
The pebbles are contained in silicon carbide, so I dont see how they will burn. They are stable up to 2800 degrees.
The silicon carbide layers are very thin and one could imagine scenarios where they are damaged and can permit oxygen leakage (from neutron irradiation , thermal or mechanical shock). In the German prototype PBR the graphite spheres were damaged by insertion of the control rods.
Pebble-bed reactors have other issues, including the fact that they are excellent Plutonium breeders (continuous fueling cycle and low-enrichement fuel).
There is another question I'm very curious about;
how exactly do you re-process spent fuel from a PBMR? As you point out, the silicon carbide/graphite spheres are very hard to dissolve - but you have to do that in order to extract the fission products. If you don't re-process the fuel then they aren't a particularly efficient use of the fuel.. Just curious about that one.
I'm surprised it took this long for the Chinese to announce this; it's obvious they will have to turn to nukes, since they don't have any oil and we (the U.S.) have troops in any place with substantial oil reserves... At least they didn't decide on nothing but coal.
But I do have a problem with the pebble bed design: it's a graphite-moderated reactor. That means that sooner or later they are going to have a graphite fire, with a lot of dispersal of radioactive material as a consequence. The pebble-bed may not be prone to a conventional melt-down, but if they ever have a leak and air gets into the reactor (which is probably at 1000+ deg C) then you'll have a fire. And they thing is that you can't put out such a fire with water - the water would act to moderate the neutrons and set off a nuclear reaction. Graphite-moderated reactors also have other issues, such as Wigner energy, which caused at least one reactor fire...
Always a good way to start a discussion on civics, don't you think? Right back at ya, knucklehead.
Since when does shoe-bomber dude have the right to a lawyer? He was arrested in England, and he's NOT an American citizen. What rights does that give him?
He was arrested when the plane he was on landed in Boston. He is a British citizen. However, you seem to have missed the fact that all criminals in U.S. courts, regardless of citizenship, have the
right to a fair trial.
American citizens have all the rights they so richly deserver.
Actually, the rights outlined in the Bill of Right apply to "all persons", not just Citizens. Recall the preamble and its discussion of "all men are created equal... endowed with certain inalienable rights."
Can you please explain to me why U.S. citizens deserve more rights than other people? Why they "deserve" rights at all?
He specifically mentioned that he had no intention to learn how to land. HE TOLD HIS FLIGHT SCHOOL TEACHER!
So if there is so much evidence against him - and I'm not arguing that there isn't- then why don't you trust the courts to come to a guilty verdict?
If he is a terrorist he can and will be convicted; there is no need to shred the Bill of Rights just to get one guy. Our system of laws and rights has worked pretty well for 200 years; why do you want to replace it now?
Raybender, you must be a Democrat.
And you, sir, are not only an anonymous coward but an example of why constitutional rights are needed.
Yes, they do. Under the Geneva Conventions enemy combatants (by which one means folks openly identified as members of an armed, hierarchical force) are to be treated as prisoners of war and as such are e.g. not to be placed in naked pyramids and led around in leashes.
Jose Padilla and the Shoe Bomber are classified as enemy combatants because they are associated with an entity we declared war on.
You mean al-Qaida? This is a murky area, because al-Qaida isn't a national entity and could not
sign the conventions even had they wanted to.
Likely the legal situation is that they can
be treated as members of a criminal conspiracy; even such people have the rights of accused criminals.
Because they did not identify themselves with a uniform, they have no rights, not even under the Geneva Convention
I think you mean "unlawful combatants" rather than "enemy combatants". However, even those who do not wear uniform have rights; under Article 4 they are to be treated as "protected persons", and if they have e.g. committed murder are to be tried and prosecuted appropriately. By the way, it is not a slam-dunk that the Taliban should not be considered
lawful combatants; they were hierarchical and organised and had as distinctive "uniforms" as certain U.S. special forces and snipers had.
Then there is also the argument that they should be considered members of a - lawful - national popular resistance movement, which have recognised rights under the conventions.
In any case, under the Conventions, the status of prisioners must be determined by "competent tribunals", not arbitrary decree of the belligerent power.
Neither is Iraq, so we don't have to obey the GC there either.
I believe that Iraq ratified the Geneva Conventions on 14 February 1956.
In effect, they are like captured spies, and captured spies have no rights, not even under the GC.
GCIV Article 5, even a spy or saboteur shall be "treated with humanity and, in case of trial, shall not be deprived of the rights of fair and regular trial".
The Gitmo detainees are all enemy combatants and prisoners of war. They have no rights, not even under the GC. (See above).
Simply not true. (see above). POW's have rights. Civilans in occupied territories have rights, and all prisoners are to be treated humanely. From what we've seen and heard, this is not the case in U.S. prison camps.
The Patriot Act doesn't override the need for warrants. Police and FBI still have to obtain them
The Patriot Act:
allows law-enforcement in ordinary criminal cases to get a warrant to track which websites a person visits and collect general information about the emails a person sends and receives. Law-enforcement doesn't have to prove the need; the judge only has to determine that law-enforcement has "certified" that this relates to an ongoing investigation. In other words, the judge cannot reject an application based on the merits.
In plain English, the warrant process has become a rubber stamp and the judge has no authority to refuse. That's not what is meant by requiring a warrant; we do NOT do the same against organised crime.
The city is allowed to prevent people from "peacebly" assembling, where such assembly isn't peaceful and interferes with other's rights.
It appears to have been peaceful, and if the rights
of 200,000+ to assemble and protest can be overridden by the right of 10 people to walk their dogs in a public park, then the First Amendment is hollowed out.
He asked you to cite some rights that you lost, not that a bunch of thugs lost.
(yeah, I know. 'We are all a bunch of thugs' or somesuch profound response)
Do I really have to explain the meaning of "equal protection under the law" to you?
You know, since only criminals need rights, why bother with rights at all? If you never break the law, you'll never need the right to an attorney, no?
Slashdot Mirror
As what? A janitor? No scientist would make comments like that, because a real scientist knows how unpredictable this sort of work is.
Yes, as a scientist. I'd be happy to compare degrees with you anyday, Mr. Anonymous Jackass. A real scientist also knows how important public support is; without public enthusiasm, there will be no more 3-billion dollar missions.
The Mars rovers did "real science", and they had a PR operation that blows ESA out of the water.
I am so pissed off right now I can hardly speak!
A few years ago I was working on a NASA project - nothing secret. We had a Canadian summer student come and work for us on a small job (writing some code to control some optics). As a foreign national he had to get clearance, but he was allowed to start working on writing some code for the project while we waited. Six weeks later his application was rejected and he was no longer allowed to touch any of our computers, or look at any code, including the code he'd written himself. Now he works for a European project doing the same sort of stuff, and I know they are very happy to have him. Stupid, short-sighted xenophobic policies like that do nothing but hurt this country.
I think the problem with this kind of stuff is that it's the people who are valuable, not the ideas. Policies that try to lock down ideas just drive away good people.
Why do we Americans always seem to assume that we're somehow that much smarter than everyone else, and if we keep our research secret then the Chinese, or Indians, or God forbid, the Canadians won't figure it out on their own? Somehow we have a situation where the security folks (who it seems are all all-American white boys from Texas) write policies to prevent the scientists (who are to a surprising extent foreign immigrants) from actually getting anything done. Of course, in the end, it's the scientists who come up with the technology to keep the secirity guys (and their families) safe. That's just too complicated for these dumb white boys to grasp, I guess.
When it comes to basic research, it's amazing how even seemingly trivial impediments to access and communication can utterly inhibit progress. Sure, it's only a biometric card, but the additional hassle will mean that you are that much less likely to hire say, that Polish kid who just happens to actually have a good education in math. Given that U.S. high schools just aren't producing kids that know math, that's a real problem. And yes, I know I do most of my useful work late at night and on weekends, so inhibiting access on non-standard hours is a real pain.
My most fundamental objection to all this though, is simply that I don't WANT to live in a society where Big Brother constantly monitors my every move, knows what my retina looks like, keeps track of who I meet and what I read, what I say, and how I spend my money. I understand that access control to military research might be needed, and that's why I don't do military work. But when they want civilian researchers (like NASA) to follow suit, then I don't have any choice. And I hate that.
I'd be extremely skeptical of this until someone shows some real discussion (i.e. not just puff-pieces on space.com) as to why this is feasible. Anyone? Of course, you also have to show that fusion using He-3 can be done (it's harder than D-T fusion, which we still haven't mastered, I might add).
I am an astronomer, and I've worked on AO systems, and I can tell you that I'd rather have Hubble than all the AO-corrected Kecks in the world. AO sounds like a good idea, but in the end the data you get out is hard to calibrate, and unreliable. The problem is that the properties of the atmospheric turbulence keep changing, making it hard for the AO to keep up. The best AO-systems available today achieve maybe 70% of the performance of a diffraction limited system such as a telescope in space. But the remaining 30% of the light goes into a big "halo" that has all sorts of complicated image structure in it.
Then there is the fact that the field of view that you get with an AO system is much, much smaller that you'd get with Hubble. And then there are issues with higher thermal background, etc. A while back HST published a light-curve of an eclipsing extra-solar planet - something like that could never be done from the ground (i.e. with the same precision).
The University of Arizona's $120 million Large Binocular Telescope is the world's most powerful optical telescope, with images about 10 times as sharp as the Hubble's.
No, not really. LBT will not produce sharp images in the visible, at least not with any AO system that one could build today. In the near-Infrared LBT will still be subject to all the disadvantages inherent in AO systems, and in addition will have the problems associated with interferometry, since it is actually two telescopes cobbled together to act as one. LBT will, if it ever works, and press-releases notwithstanding, not be quite the Hubble-killer it's sometimes made out to be.
Bush seems to think that a) there are no global-scale problems, b) even if there were, they should not be solved through collective action and c) the U.S. has a divine right to screw the rest of the world, take their resources, install oppressive regimes, etc etc.
The rest of the world doesn't like getting screwed. And half of the U.S. voters are smart enough and civilised enough to realize that sometimes co-operation is the better way. But it doesn't matter - the world isn't a democracy, and as we know, a few idiots in the "heartland" have taken all the world along for a demonstration of what happens when you let Enron-style capitalism and religious fundamentalism run things.
The good news is that now we'll all find out who is right. Are those who warn of the dire consequences of unilateralism, pre-emptive war, environmental destruction etc etc. just being whiny, or not? Maybe global warming really is just a conspiracy among scientists who want attention and funding. Maybe freedom and U.S.-style free markets will bloom in Iraq, and be so wonderful that the Palestinians will realize that they should strop trying to get back their land and go get a job for McDonalds. Maybe the "expert" opinions of the NAS, or the U.N., or our oldest allies, are just plain wrong, and reality will yield to faith.
I'm rather curious, actually. It's not every day that you get a chance to see your beliefs put to the test. Besides, it'll be fun - kinda like watching NASCAR; it's more fun when you think there will be a wreck.
I would argue that most physical scientists will disagree with much of what is claimed by "philosphers of science". Violently, or at least vehemently, in the case of the "French folks" you mentioned - see the Sokal affair.
"This phenomenon could generate a dramatic revolution in technology, which would result from a dramatic paradigm shift in science. Anomalies are the key to all paradigm shifts"
This illustrates a classic logic problem: though perhaps all advances come from "anomalies", not all anomalies imply advances. Or put another way, Einstein may have been thought a cook, but that does not imply that all cooks are Einsteins. (Of course, not even Einstein was thought to be a cook - his theory very quickly was accepted).
As you've no doubt been told a million times by now, the cost of research is dwarfed by the advertising budgets. This is because company execs have figured out that a dollar spent advertising a drug you already have for a new disease returns at least twice as much as that same dollar spent trying to develop new drugs. That's why heartburn became "acid reflux disease".
The big, dark secret of the drug industry is that they just aren't very good at finding cures. I could name more than one large company with empty pipelines... This despite the fact that they receive what is in effect an enormous subsidy in the form of government-funded basic research. Part of the problem is that the for-profit modus operandi of "patent everything and let the lawyers sort it out" actually does more to stifle science than it does to stimulate it. Sure, there are now many companies that make their money selling licenced lab products and techniques to drug developers, but this just means that a lot of effort gets wasted in a) trying to do your science without infringing on 50 different patents, or b) raising funds so you can actually afford to pay for the one crucial step that would take 30 minutes in the lab with a heat-block and some enzyme.
Can you please give an example? If not, and you seem to back off from your charge, why do you base your opinion on an impression that you admit is false? That just makes no sense to me.
Personally I started out luke-warm towards Kerry, but the more I hear him speak the more I realize that a) the man is very intelligent and knowledgeable, b) the man thinks very deeply about issues in front of him, c) he did a good job leading and taking care of his crew in the Mekong delta, and d) he volunteered to risk his life out of a sense of duty to his nation. That has to speak to his character.
The more I see Bush the more I realize that he's just plain out of his depth. He doesn't belong anywhere near the big red button.
btw, can anyone can tell me what makes GW so much worse than other past presidents? Just as some examples, I think his dad was MUCH worse by pulling out of Iraq,
41 was smart enough to realize what a disaster he'd have on his hands if he took Baghdad; the U.S. wasn't and isn't prepared to deal with the aftermath of destroying a country like Iraq. That should be obvious by now.
and John F Kennedy nearly annihilated the entire planet because he wouldn't just make a deal with the russians (sure it would be a small sign of weakness, but jesus christ, the alternative is crazy).
Where do you get the quaint notion that Kennedy didn't make a deal? At the time of the crisis we had 25 Jupiter missiles stationed in Turkey, a threat that nicely mirrored placing missles in Cuba. Within six months of the crisis those missiles had been decommissioned, ostensibly because they were no longer needed. But we did not have our first wing of Minuteman I missiles fully operational for a couple years after that, so I'm not sure that argument holds.
In the case of a thermonuclear weapon, the problem is how to uniformly compress the fusion fuel until it ignites. You can't achieve the necessary uniformity using multiple explosions. However, if you enclose the fusion fuel and the fission trigger inside a large cavity, the X-rays emitted by the fission trigger will be trapped in the cavity (for a few microseconds) long enough to come to equilibrium. This radiation field then puts uniform pressure on every surface inside the Hohlraum, including the fusion fuel, thus compressing it.
This is the Teller-Ulam process, and it was officially classified until the 70's or 80's. Of course, like all great ideas it's a fairly obvious one (every major nuclear power discovered it independently), and so the classification was kind of silly. Not that that stopped the various governments from trying to keep it a secret - of course the existence of fusion weapons wasn't secret, so there was a bit of mis-direction put out there, in particular the idea that compression was achieved by surrounding the fuel with multiple fission triggers.
Out of curiosity, what did I get wrong in my post? I really am curious; nukes have been a long-standing interest of mine (geek that I am), and though I am not a weapons-physicist, I am trained as a physicist and have talked a fair amount with folks who built bombs (I took a couple of physics classes from a guy who used work on bombs - one of the most memorable times was when he explained in detail how the castle Bravo test gave a much larger yield than predicted. I'm glad that I work in a field where if I make a miscalculation the worst that happens is a delayed research paper, not 6 extra megatons of explosive yield.
Close, very close, but not quite right. The trigger is a single fission bomb; the radiation it produces is redirected cleverly so as to compress the fusion charge (a concept referred to as a "Hohlraum"). In some designs there are more than two "stages" where fission triggers fusion, which then is used to trigger more fission or, in some cases, another fusion stage (the Soviet "Tsar Bomba" was a multistage fusion device of 60-120 Mtons. Check out the Nuclear Weapons FAQ for more info.
The "neutron bomb" was a planned attempt to replace the fission warheads with chemical explosives, creating a thermonuclear explosion with no radioactive fallout- a truly impressive feat if it were possible.
Not the neutron bomb I'm familiar with. It was a very low-yield fission-triggered device that had a fusion stage. There has long been a dream at LLNL to figure out how to initiate fusion with a conventional high-explosive trigger, but to my knowledge, no such weapon has ever been tested or fielded. The neutron bomb of the 80's would have created plenty of fallout and radioactivity; the point was it created less blast damage and so didn't sound as bad (the fallout was sort-of ignored).
He is talking about the tritiated lithium hydride,....Since the bomb was lost 46 years ago, which is about 4 tritium half lives, the maximum possible yield has in theory been reduced to 1/16 of what it was in 1958, and the actual yield is probably zero.
I think there is a small mis-understanding here. A fusion weapon of this type uses tritium to boost the yield of the fission trigger, NOT as a component in the fusion main stage fuel. The fusion stage creates the tritum needed at the time of explosion by neutron-spallation of the Lithium. So, after 4 half-lives the fission trigger yield will be greatly reduced - probably enough to prevent any significant second-stage fusion. This means that if it exploded, the yield would be in the 10-kiloton range, not the megaton range. However, if the fusion stage were to ignite, it would do so with as much yield as ever.
That's rather arguable. I will agree that computers have progressed rapidly, though not in the way many SciFi authors thought (i.e. no artificial intelligence). But nanotech? I can't think of any significasnt breakthrough in nanotech...
Could this cloud have been the result of a U.S. strike against a North Korean nuclear facility? Maybe we located the place where they keep all of their bombs and just took it out?
#end tinfoilmode
I know, I can think of a million reasons why we shouldn't do something like that, but maybe we did anyway. It's not like this administration is beyond acting like cowboys...
I've actually worked there, and I remember that day. Now I really wish I hadn't spent a good part of that day outside in the rain. For years afterward there was a bit of a "hotspot" just north of Stockholm where that rainstorm had washed a bunch of stuff out of the cloud and onto the ground.
As for the possibility of civilians detecting a nuclear test - that depends on a lot of variables such as how the wind blows. Given the geography of the location, the cloud might go out over open ocean or over China, in which case you won't hear anything from civilians. Or it could blow over Japan, in which case some university scientists might notice something.
Certainly the U.S. knows if it was a nuke thanks to our satellite systems; but the current regime may not wish to publicise such a failure of their anti-proliferation policy just before an election.
In any case, I would have thought that the North Koreans would make an announcement if they had actually had a successful test. Why wouldn't they? I know they certainly trumpeted up their attempts at a space launch.
Then things just stopped. We never went back to the Moon. The Concorde stopped flying. We no long dream of flying higher, faster, better. The Shuttles blew up or were lost, space exploration was curtailed.
Sure, there has been much progress in the area of computers, but not as much as hoped (Hal 9000 anyone?). And the progress there is just makes Orwell look more prescient than, say, Heinlein or Clarke. The future we have isn't so exciting, and certainly isn't worth writing much about. At least not if your aim is to excite young kids about adventure, science and exploration.
It's a matter of frontiers - before SciFI there were Westerns; different setting, same basic idea. SciFi will come back if we ever enter a new age of exponential progress in exploration. Until then, the stories will be escapist fantasy...
Are you trolling, or just crazy? I bet the Taliban or the "insurgents" in Fallujah would love to be able to lob mortar rounds at real, live nuke plant. Not to mention if they got luck and managed to steal some nuclear material...
With all due respect to the above journals, they are not peer-reviewed journals where research results are reported. If the journals had been Nature, Science and Physics Review, then I'd be excited. But they aren't, so I'm not. Besides, I read the articles, and I didn't get the impression they were all that enthusiastic...
The silicon carbide layers are very thin and one could imagine scenarios where they are damaged and can permit oxygen leakage (from neutron irradiation , thermal or mechanical shock). In the German prototype PBR the graphite spheres were damaged by insertion of the control rods.
Pebble-bed reactors have other issues, including the fact that they are excellent Plutonium breeders (continuous fueling cycle and low-enrichement fuel).
There is another question I'm very curious about; how exactly do you re-process spent fuel from a PBMR? As you point out, the silicon carbide/graphite spheres are very hard to dissolve - but you have to do that in order to extract the fission products. If you don't re-process the fuel then they aren't a particularly efficient use of the fuel.. Just curious about that one.
But I do have a problem with the pebble bed design: it's a graphite-moderated reactor. That means that sooner or later they are going to have a graphite fire, with a lot of dispersal of radioactive material as a consequence. The pebble-bed may not be prone to a conventional melt-down, but if they ever have a leak and air gets into the reactor (which is probably at 1000+ deg C) then you'll have a fire. And they thing is that you can't put out such a fire with water - the water would act to moderate the neutrons and set off a nuclear reaction. Graphite-moderated reactors also have other issues, such as Wigner energy, which caused at least one reactor fire...
Always a good way to start a discussion on civics, don't you think? Right back at ya, knucklehead.
Since when does shoe-bomber dude have the right to a lawyer? He was arrested in England, and he's NOT an American citizen. What rights does that give him?
He was arrested when the plane he was on landed in Boston. He is a British citizen. However, you seem to have missed the fact that all criminals in U.S. courts, regardless of citizenship, have the right to a fair trial.
American citizens have all the rights they so richly deserver.
Actually, the rights outlined in the Bill of Right apply to "all persons", not just Citizens. Recall the preamble and its discussion of "all men are created equal ... endowed with certain inalienable rights."
Can you please explain to me why U.S. citizens deserve more rights than other people? Why they "deserve" rights at all?
He specifically mentioned that he had no intention to learn how to land. HE TOLD HIS FLIGHT SCHOOL TEACHER!
So if there is so much evidence against him - and I'm not arguing that there isn't- then why don't you trust the courts to come to a guilty verdict? If he is a terrorist he can and will be convicted; there is no need to shred the Bill of Rights just to get one guy. Our system of laws and rights has worked pretty well for 200 years; why do you want to replace it now?
Raybender, you must be a Democrat.
And you, sir, are not only an anonymous coward but an example of why constitutional rights are needed.
Yes, they do. Under the Geneva Conventions enemy combatants (by which one means folks openly identified as members of an armed, hierarchical force) are to be treated as prisoners of war and as such are e.g. not to be placed in naked pyramids and led around in leashes.
Jose Padilla and the Shoe Bomber are classified as enemy combatants because they are associated with an entity we declared war on.
You mean al-Qaida? This is a murky area, because al-Qaida isn't a national entity and could not sign the conventions even had they wanted to. Likely the legal situation is that they can be treated as members of a criminal conspiracy; even such people have the rights of accused criminals.
Because they did not identify themselves with a uniform, they have no rights, not even under the Geneva Convention
I think you mean "unlawful combatants" rather than "enemy combatants". However, even those who do not wear uniform have rights; under Article 4 they are to be treated as "protected persons", and if they have e.g. committed murder are to be tried and prosecuted appropriately. By the way, it is not a slam-dunk that the Taliban should not be considered lawful combatants; they were hierarchical and organised and had as distinctive "uniforms" as certain U.S. special forces and snipers had. Then there is also the argument that they should be considered members of a - lawful - national popular resistance movement, which have recognised rights under the conventions.
In any case, under the Conventions, the status of prisioners must be determined by "competent tribunals", not arbitrary decree of the belligerent power.
Neither is Iraq, so we don't have to obey the GC there either.
I believe that Iraq ratified the Geneva Conventions on 14 February 1956.
In effect, they are like captured spies, and captured spies have no rights, not even under the GC.
GCIV Article 5, even a spy or saboteur shall be "treated with humanity and, in case of trial, shall not be deprived of the rights of fair and regular trial".
The Gitmo detainees are all enemy combatants and prisoners of war. They have no rights, not even under the GC. (See above).
Simply not true. (see above). POW's have rights. Civilans in occupied territories have rights, and all prisoners are to be treated humanely. From what we've seen and heard, this is not the case in U.S. prison camps.
The Patriot Act doesn't override the need for warrants. Police and FBI still have to obtain them
The Patriot Act: allows law-enforcement in ordinary criminal cases to get a warrant to track which websites a person visits and collect general information about the emails a person sends and receives. Law-enforcement doesn't have to prove the need; the judge only has to determine that law-enforcement has "certified" that this relates to an ongoing investigation. In other words, the judge cannot reject an application based on the merits.
In plain English, the warrant process has become a rubber stamp and the judge has no authority to refuse. That's not what is meant by requiring a warrant; we do NOT do the same against organised crime.
The city is allowed to prevent people from "peacebly" assembling, where such assembly isn't peaceful and interferes with other's rights.
It appears to have been peaceful, and if the rights of 200,000+ to assemble and protest can be overridden by the right of 10 people to walk their dogs in a public park, then the First Amendment is hollowed out.
Do I really have to explain the meaning of "equal protection under the law" to you?
You know, since only criminals need rights, why bother with rights at all? If you never break the law, you'll never need the right to an attorney, no?
Idiot.