When I said "seepage", I meant seepage into local surrounding communities. That's the main concern with radiation nowadays.
The FAA will handle the restriction of airspace above. They already do a good job with other dangerous objects, like balloons, etc. That I wouldn't worry about.
Also, I didn't say "coherent". I said "collimated", which means unidirectional - the reason you can't see even optical lasers, because they aren't radiated omnidirectionally, but unidirectionally. The two main properties of a laser beam are coherence (useful! for signal transmission) and collimation. The second property prevents any worry from 'leaking' radiation.
This level of concern definitely falls under the heading of "no one cares" in my book. Unfortunately, studies like these are extremely subjective and can be easily biased by many factors, not the least of which is the predilections of the surveyor.
A bit of fact, pure and simple: the human body emits about a kilowatt of power, mostly in the infrared. Most people know this from "The Matrix" - I actually had to figure it out in one of my entrance astrophysics classes (it was fun, actually. Though I'm not sure the 'approximate yourself as a blackbody' argument is convincing). By this argument, standing one meter away from a person you're being pounded on by about 10 watts/sq. meter. That's huge orders of magnitude above the levels mentioned here! Can you imagine what would happen if you were standing in a crowded room? Or in a subway? That's practically a kilowatt of radiation you're absorbing there.
Oddly enough, I bet I could start a survey and find out that the mortality rate is higher in a city than it is in the country.
Am I being a bit sarcastic? Yes. However, to be honest, in this area, surveys exist on both sides of the spectrum. Surveys exist that say 'all radiation is fine' and some surveys exist that say 'all radiation is bad'. The best way to say it right now is that it's inconclusive, however, more studies have been done that say it's fine than that it's bad. Search for yourself - the surveys you found are the exception. Except look in journals, this time, rather than online.
I'd do it for you, and post the results here, if I could, but unfortunately right now I don't have access to a journal database. Your local university will probably have one in its library.
Except for the fact that none of the radiation seeps. It's a laser - it would be collimated. People would have no idea that it is anything other than a large satellite dish.
Radio antennas give off radiation too - radio radiation. No one worries about radio radiation - there are plenty of people right beside a radio tower - hell, some are built in the middle of cities. Somehow I've got a feeling no one will really care, at least, after a few years of no one dying because of it.
You are in more danger from your microwave oven than you would be from these things.
Besides, NASA isn't stupid. They'd probably build it in New Mexico, where it's flatter anyway and easier to build a directional array. People wouldn't be an issue.
Actually, momentum is not the product of mass times velocity solely. Fields can carry momentum and energy, and a photon is a quantum of oscillating electric and magnetic field. For a photon, the momentum carried is directly proportional to the energy of the photon, with a constant of proportionality of the inverse of the speed of light (energy = momentum * speed of light).
The sails reflect light. Which is beneficial, since it means that twice the momentum is transferred into the sail as would occur if the sail absorbed it.
One thing that science absolutely loves is alternatives. There are multiple methods to solve any problem. Look at semiconductors - for most purposes, silicon is far superior to germanium as a basis for semiconductor devices. However, germanium devices are still made. Why? Because they are useful in certain tasks, and they are improving.
Ion drives have limitations. Slow acceleration, for one. Second, they still require weight to be carried, so that liftoff is still heavy. Third, they do contain slightly expensive materials (if memory serves, the one on DS1 used xenon ions - xenon is pretty expensive. Not that expensive, but still expensive). Fourth is again, the lack of acceleration - which means you can't change course. At all. Or slow down. You'd need to slow down at the same rate you sped up.
Sails have many advantages, but by far the weight requirement is the greatest. Low weight means little energy needed for fast acceleration and high speed. Therefore it is more efficient to use sails rather than ion drives for many applications.
Ion drives are not a panacea for space travel. Far from it! Sails actually offer a very good possibility for intra-system transport, and ion drives do not.
On a personal note, I do not think it is a good idea to second-guess the research decisions of people who are in a field you are not in. If they are working in your field, then, yes, you can have a valid criticism. But if you are not working in that field, you do not know all the information, and therefore, cannot make an informed comment.
I highly doubt that NASA is financing anything with the word 'space' in it - and research like this is ridiculously cheap compared to actual space projects - a pathetically small amount (thousands compared to millions). Spending a fraction of your money on research that could potentially save you a large fraction of your money isn't bad business - it's good business.
Why pipe energy back? Why stay on this planet? Piping energy back is a waste - you lose energy in transmission. The best option is to get the heck off this planet and create our own world. Whether or not we could maintain our own ecosystem - hmm, that is a question, but to be honest, I'd rather place my trust in the hands of scientists than in the hands of capitalists.
Besides, and here is an argument I didn't think of before (but others have) - if we leave the Earth, and try to set up a world somewhere else, if we fail, we just come back to Earth. If we stay here, and try not to screw up the Earth, if we fail, we all die.
Thanks for the clearing up of info - my solar nuclear physics is better than my man-made.
However, my point was that people were trying to claim that saying "with fusion" was a cop out because we didn't have fusion yet. While that's true, He-3 is helpful for us in using fusion, and possibly developing it. He-3 is in pretty sparse supply on the Earth's surface (it does exist, but in low quantities - much worse than deuterium and tritium, as you know) - so experimenting with it is costly. Though unlikely, it's possible that experimentation with He-3 would uncover a method to actually make it work (very unlikely, but possibly not - the fact that He-3 has twice the charge of a triton can be useful in some instances - possibly magnetic bottling, where the same magnetic field strength will cause twice the containment force). Don't forget - virtually nothing in science has ever come out of theory before it's come out of experiment, so it's always useful to run them, even if you think you know the answer.
I didn't include numbers because, basically, numbers don't exist yet. As far as I know, no one has done a study on the potential environmental impact of solar energy exploding as an energy source. As it is now, of course, it's perfectly safe. The fact is, though, unless we use energy from outside the Earth, that energy was meant to go somewhere, and using it excessively means potentially having ecological side effects.
Another problem: solar power isn't continuous, so now in addition, we need an energy storage mechanism. Want to power the Earth with solar energy? You need one hell of an energy storage mechanism! Energy storage isn't perfect, so you'll lose a bunch there as well. Not only that, but you'll probably have to do it with something that's either consumable, or requires energy to initially create.
Additionally, don't forget that during the winter, a good portion of the Earth doesn't get *any* sunlight - or negligible sunlight. ("Sorry, Helsinki, but you can't have any power for about a third of the year.") No energy storage mechanism could possible store enough energy to power Helsinki for a few months, so now we'd have to have an energy grid across the entire world. Energy transmission incurs large transmission losses, not to mention the massive infrastructure cost and maintenance.
Solar power not only isn't feasible, it isn't environmentally sound, even using your numbers which are *very* generous (photocell efficiency is around 15-25%, not very much more) - 0.08% of the area of the Earth is around 36 million square kilometers. Regardless of whatever you do, those portions of the Earth will have drastically different properties than they were intended to, and will, in some way, end up radically changing the environment, I'm sure.
Unfortunately that's not really a wonderful argument (the first portion) - the amount of energy lost in slowing down and speeding up is miniscule on any decent sized trip. It can be large, but usually it is not that important. Drag dominates everything, by far. Friction is pathetic (remember, friction only generates a constant force, so you'd only need an engine to start moving, rather than to accelerate. On an airless planet, all speeds are equally efficient. Since it is distinctly known that there are "most efficient speeds" for cars, drag really must dominate.
You can immediately see how much energy it must take to overcome friction - just try to push your car with the brake off. It's not that hard at all. At highway speeds, friction is more of an annoyance than anything else. After all, in most cars, with the car in gear and the foot off the brake, the car will begin to move. Therefore, if it wasn't for drag, at highway speeds a car could *idle* and still move.
And as for the slowing-down/speeding-up argument, remember that the in-town/in-highway miles per gallon only change by a tiny amount - at most 30% or so, at least about 5%. Since slowing down/speeding up only occurs once on a highway trip, again, drag must truly dominate.
So, unfortunately, the -pure- energy efficiency of electric cars vs. gas burning cars may still be in question. My guess is that the energy efficiency award could ultimately go to a car, *with* an intelligent enough design, and also only in most situations. However, currently, with the piece-of-crap internal combustion engine located in most vehicles, an electric car nowadays will win out.
There is still, of course, the issue of pollutants, and as you noted, electric plant generation of heat. However, I would note that adding additional power plants, while significantly cutting down on global pollutants, would significantly increase local pollutants, destroying local habitats and doing much more -visible- damage. Therefore, to people, it may appear as if electric cars have done more damage than gas cars did.
Those tribes might get a bit freaked out when the moon slowly gets farther away as it eventually will. At some point, it may not even be visible in the sky for them anymore! Maybe we should go blow up a nuclear bomb on the moon to make sure things don't change for those tribes. (/sarcasm)
First off, this is definitely old knowledge. The existence of He-3 on the moon is completely well known and has been for a while.
The "combined with fusion" thing is not exactly a cop-out. What they meant was that using He-3 as a fuel for fusion can produce quite a bit of energy, and He-3 is a very useful catalyst for fusion. Why? Same reason that deuterium is beneficial - because you're bypassing some of the steps in the p-p chain (the process that the Sun uses to make helium out of hydrogen). Basically, you can lower the energy threshold of sustainable fusion reactors if you already have tritium, deuterium, and Helium-3 present, because now instead of reaching the energy threshold of just one reaction (proton-proton -> deuteron) you can reach any of the steps in the p-p chain immediately. It's similar to chemistry - you can speed up a reaction if you have some of the intermediary products already available.
Second comment: what the heck are people complaining about using the moon for energy? You think solar power is better? Really? You really think it's free? Just like wind and water power is free, huh? Solar power is great - on a small scale. Try to use it for the reasons you want to use it for - like powering the *world*, for instance - and you might have a problem. All that solar energy was meant to go somewhere - the air and the ground. There's a definite solar thermal cycle, and stripping out energy can affect it. On the scales that people typically use it for now, like powering lights or scientific instruments, it's fine. Even maybe for a few supplemental reactors. But if you honestly wanted to power the world with it, you better start realizing that power generation will always hurt the environment. Always. Period. End of story.
So, then, the answer is, why the hell do we care what we do to the moon? It's *dead*. It's static. It's unchanging. Study it for a while until you mostly understand it, and then you're free to do with it what you want. Helium-3's a good idea - very good in fact. And yes, when we run out, we move on to another planet. Is this a problem? No. These planets were static. They weren't changing. We're not *affecting* anything that was important to begin with.
Here's a bit of reminder before I get flamed for being an anti-environmentalist or something strange like that. Life is destructive. It's entropic. But who cares? That's the point of the entire friggin' universe.
Interesting scientific point. Entropy is mathematically identical to the concept that Shannon (yah, the modem guy) called 'information', and it's quite appropriate. Entropy is information - it's the universe saying "Something happened here." So when people say that entropy always increases, that's correct - because things are happening - information is being generated. Thermo tries to tell us that this is a 'bad' thing - they call entropy chaos, or disorder. That carries a connotation of evil or wrong, which is not right - it's simply a way of saying "something happened here."
So we have two choices. We can avoid energy use entirely, and calmly sit here on the planet, maybe migrate when it dies, and do nothing. Might have to destroy most of Nature too. Nature is rather entropic... eats up a lot of power and just turns it into heat. Or we can do what living beings were intended to do. Live. Use the fuel that the universe gave us - just, try to make it last as long as possible. Not infinitely. We can't live forever, and we shouldn't try to.
Bottom line - there's nothing wrong with using up resources. They're there to be consumed, or else they'll just sit there forever. The real goal is to use them intelligently. In my opinion, using a big rock whose entire job seems to be to act as an asteroid shield and a tide generator as a power source is pretty damned intelligent.
Illogical hand waving? Find the error in my argument and explain it, rather than claiming it's simply illogical.
I'm not claiming my doctrine is correct. In fact, I'm claiming it's not correct - at least, not completely. What I *am* claiming is that the claim of the person previously, which was that the collapse of the wave function can be explained by particle interactions, is wrong. Here's the kicker - he's using the same doctrine I am - quantum mechanics! This is *math* we're talking about here, pure and simple differential equations. Computers can solve them (pretty well, actually). Math has a right and a wrong, and it's not based on any complex that I have.
(Incidentally, I wasn't insulting the previous person - he claimed that everyone else was being stupid, and challenged someone to show that he was wrong. I took him up on that challenge.)
Finally, because flames don't particularly amuse me, coding is no better than physics in this regard. Look at Microsoft. Windows compiles. It seems to work. Is it a fact that it's well coded then? Yah. Right. If you think an uptime of about 4 days on average is "well coded". Not to mention the philosophical arguments as to whether or not microkernels or monolithic kernels are better, or any other piece of coding.
If you think physics is all about philosophy, you're quite dead wrong. Physics is as much about philosophy as computer science is.
And just to get my small flame in, you go right ahead making machines work. When you want more processing power than the speed of light allows, I'll just sit back and smile as you come crawling to me (or physicists in general). I do physics because I want to do more than make a few things better - I want to make *everything* better.
Learn the physics first, please. You don't exactly understand what they're talking about.
Imagine an electron is in a mixed state, that is, it is not in a measurement eigenstate (i.e. it is not 'definite' what the result of the measurement will be). Now, *observe* the electron. I don't care how. Just make it so that macroscopically, the state of the apparatus is linked one-to-one with the state of the electron. Now, the question is, when you observe the apparatus, you don't see a superposition of eigenstates - you see one eigenstate. This is what is typically referred to as "the collapse of the wave function."
Your explanation would be "well, you scattered an electron or something off of it, and that changed the state and 'somehow' that pushed it into an eigenstate." Good explanation. Two points for trying.
Too bad you're wrong. Quantum mechanics knows how particles interact - they interact via the Schrodinger equation. You can do the basic QM for the apparatus/electron interaction. You do *not* get that the electron emerges in an eigenstate. (You couldn't. That would indicate a hidden variable theory, and Bell's inequality says that QM and a hidden variable theory don't work.) You get that the entire system is in a superposition of eigenstates.
This again leads you back to the previous problem. Somewhere, the wave function collapses. Guess what? We don't know where yet. We have no idea where yet. "We're working on it."
So, is there a mystery to it? Yes. Is there a *problem* here? No one's been able to find one - i.e., no one has been able to find anything other than philosophical problems with QM to my knowledge.
In conclusion, to sum up, in this case, yes, you're a total heathen. Sorry.:)
If you want a good reference to the philosophical issues regarding measurement and quantum mechanics, read J.S. Bell's Physics World, August 1990 article "Against 'measurement'" and the subsequent follow up articles in October, January 1991 and May 1991.
Oh, I quite agree- however, if you look at these papers, they're a strong argument for some form of peer-review on preprints.:) My personal favorite is the derivation of the second law of thermodynamics... note it closely and you'll see that it didn't require anything in the article at all. (Not to mention that it's a bit strange anyway, saying "F=E" and then in the next sentence saying "F=E-TS")
They are NOT papers. They are preprints. Anyone and his brother can submit a preprint. They have NOT been peer-reviewed (nor are they likely to EVER be peer-reviewed) nor have they been published at all (nor are they likely to be published at all) because they're totally bunk.:)
xxx.lanl.gov (arxiv.org) preprints should not be taken as being fact. Hardly! Wait till you see something actually *published* and then you can take it with some conviction that it isn't crap science.
Actually, it *is* a particle in the sense of a proton/neutron! What exactly do you think a particle is?
A particle is anything which carries energy or momentum. Period. In quantum mechanics, we can model vibrations of a lattice as collective excitations across the lattice ("normal modes"). These collective excitations are called phonons, sometimes called quasi-particles. But they are particles - they are absorbed, emitted, recoil, and diffract.
Quantum field theory (welcome to hell, boys and girls... enjoy renormalizations) is all about this - now, instead of some particles being collective excitations, *all* particles are collective excitations.
This basically comes down to a question of exactly what is a particle, which is usually covered in a second-semester or first-year graduate course. Particle does have a sort of rigid meaning, but you can't revert to classical thinking all of the time.
Plus you just have to get rid of that wave-particle duality crap. Waves are particles. Ever stand in an ocean? Ever get hit by a rather strong wave? (Not a crashing one, those are wierd... welcome to yet something else that physics can't describe yet) You feel it, don't you? But it's a *wave*, not a particle.
Simple answer: collective excitations of "X" field where X is some quantum mechanical field are particles.
Note that a graviton isn't a particle yet. We don't have a quantum mechanical gravity field yet.:)
Your confusion is in the definition of "transmission" and "reception" here. "Transmission" corresponds to the moment that the signal left the signal generator. "Reception" corresponds to the moment the signal arrives at the receiver. Any time inbetween is a totally different event.
In this case, what would happen for any observer in the middle of the flight path of the signal - assuming that the signal left a visible trace (Assume it does, for the moment... say, a huge blue streak) - would be that he suddenly sees a blue streak appear, in the middle of nowhere, and radiate out, faster than light, racing towards *both* the reception *and* transmission points.
Where the streak arrives first depends on where the observer is. You can write a quick expression using trigonometry to derive the location where the observer sees the streak reach the reception and transmission points at the same time.
Yes, and no. MWI/Copenhagen have existed just about as long as each other - since the beginning of quantum mechanics.
Probably the best interpretation of quantum mechanics comes from Roger Penrose, who taught a class I was in. Simply put, he said that we do not know enough to make any claims whatsoever as to the true nature of the Schrodinger's Cat problem. Which is true. We unfortunately still have several paradoxes to resolve before we can even approach explaining Schrodinger's Cat - the Quantum Xeno Paradox, for instance, which states that one can make an improbable state persist infinitely by continuously observing it - i.e., by making it continuously interact with its environment. This will tell us whether or not measurements actually do what we think they do - i.e., collapse the wave function. Currently the quantum xeno paradox favors quantum mechanics, but unfortunately the results can be easily explained away.
That's just the beginning of the problems facing the philosophical aspects of quantum mechanics. The other major hurdle is the use of the word "random". Einstein probably hurt us the worst when he said "God doesn't play dice," since dice rolls are random (more or less).
Quantum mechanics is -not- about randomness, or probability. It is about distributions. An electron in a mixed spin-up, spin-down state does not have a 50% "chance" of being measured in spin up. Quantum mechanics means *nothing* for individual particles or systems. It only has meaning for large collections of indistinguishable objects. In other words, in the previous example, an electron in a mixed spin-up, spin-down state doesn't have a "probability" of being measured in a spin-up or spin-down. It'll be measured in whatever it's measured in. However, if you take a thousand of those electrons, on the average, you'll get 500 up, and 500 down. Plus or minus 10 on both. Gotta love Poisson statistics.
*That* is the best interpretation of quantum mechanics - it's the same interpretation of statistical mechanics as well. The theory means crap for individual objects. Only large numbers of objects. Therefore, talking about "one molecule" of DNA is bunk. You need to talk about a large number of DNA molecules, all in the same mixed quantum state. Then, on the average, if their states are measured, then QM will give the right results. Not for each one. This whole "choice" thing and "quantum multiverse entering" is meaningless.
Re:Pshaw! This one's easy!
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Author Unknown
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· Score: 2
Babelfish is not a one-to-one translator, so there is information lost. Since its vocabulary is limited, multiple words may map onto one word in another language. This makes it impossible to reconstruct the original text, regardless of what you know about the program -in essence, Babelfish introduces 'noise' to the system.
However, I don't think this will inevitably fix things - the author here was talking about stylistic usages - such as quoting from sources, or common recurring words/themes - these won't be pulled out by Babelfish, though Babelfish may make it difficult to note certain patterns.
I agree with the method - I can usually recognize people online simply by word usage and punctuation usage. Punctuation is usually a total giveaway - for instance, I tend to use dashes a whole lot, and rarely (if ever) miss capitalization or comma usage (In real time chat, it becomes even easier, as you can tell roughly the speed at which someone types). You kindof "pick up" these habits after dealing with other people online quite a bit. This just takes that learned habit to a new level.
Re:Information is subject to entropy
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The Regulon
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Curious point, considering that entropy *is* information, period - mathematically, they're identical objects, with information being the log of the distribution function, and entropy being the log of the partition function, functionally identical objects, as well.
Entropy is the universe's method for keeping track that interactions happen - no, it'd probably
be better said that it's a mathematical construction with no real physical basis. Truly, if you think about entropy on a purely physical basis, it would kindof seem like magic from a macroscopic point of view - from a microscopic point of view, though, it's obvious - of course you can't revert to a lower entropy state, because something *happened* to cause that entropy state, and that 'something' can't just be forgotten. But what if that 'something' could be forgotten - i.e., it's reversible, with no energy needed? Then the process was adiabatic- no entropy change - and no information gained.
But, in any case, to your point - I don't believe the problem Katz was talking about was unwanted information - but necessary information - i.e., survival information. Our brains are remarkably good at filtering out unnecessary information from our senses - however, people don't seem to be very effective at filtering out useless directed information. We learn naturally to ignore
constant murmur around a room. We don't seem to learn to ignore constant "Horrific shooting maims 3 in supermarket slaying" on the local news - people seem to grab on stories that have been hyped and overdone, leading to a false sense of the progression of the world - i.e., 'schools are becoming increasingly more violent' when evidence shows otherwise.
I don't think that entropy is information's Regulon- I think cynicism is. Eventually, when kids grow up in a hyped up society, we won't believe it anymore. Eventually, important information will find a way to breach the cynicism, or it is ignored and filed away.
I definitely go for videogame supervillains. Unfortunately they get to be a little too like their counterparts. Sephiroth (my main machine) is just pure evil. Kefka (our server) is psychotic, and every once in a while just does something completely random, then looks innocent so he can get something. (Swear!) Krelian (spare machine) is far more powerful than you could possibly imagine at first, and Ganon (laptop) keeps having the *same* problems, over, and over, and over... It also makes me wonder whether or not those random blips on the hub aren't the computers attempting to take over the world.
The mission is not to collect antimatter. It is to identify it. The entire idea is to try to see if the cosmic ray flux contains complex antinuclei from antimatter galaxies. They won't actually be 'keeping' the antimatter - in actuality, the antimatter won't even stop in the detector, most likely.
You can't "collect" antimatter - at least, not cosmic ray antimatter. It's moving too fast.
The way they determine if it is antimatter is they use a superconducting magnet to curve the particle's path. By measuring the path (via a variety of methods, I don't know what BESS uses) you can determine whether the particle is positive or negative. Then, you also use other techniques such as time of flight analysis, and Cerenkov light produced to determine the mass and energy of the particle.
This has actually been going on since the 1960s. This is simply the newest flight of BESS. The important mission for detecting antimatter in cosmic rays is actually AMS, which is to be placed on the Space Station in a few years. Since in space you don't need to worry about atmospheric background, AMS will (hopefully) be able to see antimatter at a lower level than anything else.
Also: Antihelium that would be detected by this *would* have a charge. The possibility of finding an antihelium atom *not* ionized is *zero*. Not close to zero, just plain zero. (Okay, maybe it's like 10^-100 or something like that. But it's zero.) What they're looking for are anti-alpha particles.
Slashdot Mirror
When I said "seepage", I meant seepage into local surrounding communities. That's the main concern with radiation nowadays.
The FAA will handle the restriction of airspace above. They already do a good job with other dangerous objects, like balloons, etc. That I wouldn't worry about.
Also, I didn't say "coherent". I said "collimated", which means unidirectional - the reason you can't see even optical lasers, because they aren't radiated omnidirectionally, but unidirectionally. The two main properties of a laser beam are coherence (useful! for signal transmission) and collimation. The second property prevents any worry from 'leaking' radiation.
Yup. However, I also took the time to realise that other people might not. This way, when they read that message, they'll also see mine.
In my opinion, far too many people don't realise dry sarcasm and take it at face value, so it's a bit of a safety margin.
I also realised that I forgot to add the "I'm pretty sure this was a joke, but just in case..." line that I normally stick at the bottom.
I really don't like bad science. I do my best to prevent its propagation by any means possible.
This level of concern definitely falls under the heading of "no one cares" in my book. Unfortunately, studies like these are extremely subjective and can be easily biased by many factors, not the least of which is the predilections of the surveyor.
A bit of fact, pure and simple: the human body emits about a kilowatt of power, mostly in the infrared. Most people know this from "The Matrix" - I actually had to figure it out in one of my entrance astrophysics classes (it was fun, actually. Though I'm not sure the 'approximate yourself as a blackbody' argument is convincing). By this argument, standing one meter away from a person you're being pounded on by about 10 watts/sq. meter. That's huge orders of magnitude above the levels mentioned here! Can you imagine what would happen if you were standing in a crowded room? Or in a subway? That's practically a kilowatt of radiation you're absorbing there.
Oddly enough, I bet I could start a survey and find out that the mortality rate is higher in a city than it is in the country.
Am I being a bit sarcastic? Yes. However, to be honest, in this area, surveys exist on both sides of the spectrum. Surveys exist that say 'all radiation is fine' and some surveys exist that say 'all radiation is bad'. The best way to say it right now is that it's inconclusive, however, more studies have been done that say it's fine than that it's bad. Search for yourself - the surveys you found are the exception. Except look in journals, this time, rather than online.
I'd do it for you, and post the results here, if I could, but unfortunately right now I don't have access to a journal database. Your local university will probably have one in its library.
Except for the fact that none of the radiation seeps. It's a laser - it would be collimated. People would have no idea that it is anything other than a large satellite dish.
Radio antennas give off radiation too - radio radiation. No one worries about radio radiation - there are plenty of people right beside a radio tower - hell, some are built in the middle of cities. Somehow I've got a feeling no one will really care, at least, after a few years of no one dying because of it.
You are in more danger from your microwave oven than you would be from these things.
Besides, NASA isn't stupid. They'd probably build it in New Mexico, where it's flatter anyway and easier to build a directional array. People wouldn't be an issue.
Actually, momentum is not the product of mass times velocity solely. Fields can carry momentum and energy, and a photon is a quantum of oscillating electric and magnetic field. For a photon, the momentum carried is directly proportional to the energy of the photon, with a constant of proportionality of the inverse of the speed of light (energy = momentum * speed of light).
The sails reflect light. Which is beneficial, since it means that twice the momentum is transferred into the sail as would occur if the sail absorbed it.
One thing that science absolutely loves is alternatives. There are multiple methods to solve any problem. Look at semiconductors - for most purposes, silicon is far superior to germanium as a basis for semiconductor devices. However, germanium devices are still made. Why? Because they are useful in certain tasks, and they are improving.
Ion drives have limitations. Slow acceleration, for one. Second, they still require weight to be carried, so that liftoff is still heavy. Third, they do contain slightly expensive materials (if memory serves, the one on DS1 used xenon ions - xenon is pretty expensive. Not that expensive, but still expensive). Fourth is again, the lack of acceleration - which means you can't change course. At all. Or slow down. You'd need to slow down at the same rate you sped up.
Sails have many advantages, but by far the weight requirement is the greatest. Low weight means little energy needed for fast acceleration and high speed. Therefore it is more efficient to use sails rather than ion drives for many applications.
Ion drives are not a panacea for space travel. Far from it! Sails actually offer a very good possibility for intra-system transport, and ion drives do not.
On a personal note, I do not think it is a good idea to second-guess the research decisions of people who are in a field you are not in. If they are working in your field, then, yes, you can have a valid criticism. But if you are not working in that field, you do not know all the information, and therefore, cannot make an informed comment.
I highly doubt that NASA is financing anything with the word 'space' in it - and research like this is ridiculously cheap compared to actual space projects - a pathetically small amount (thousands compared to millions). Spending a fraction of your money on research that could potentially save you a large fraction of your money isn't bad business - it's good business.
Why pipe energy back? Why stay on this planet? Piping energy back is a waste - you lose energy in transmission. The best option is to get the heck off this planet and create our own world. Whether or not we could maintain our own ecosystem - hmm, that is a question, but to be honest, I'd rather place my trust in the hands of scientists than in the hands of capitalists.
Besides, and here is an argument I didn't think of before (but others have) - if we leave the Earth, and try to set up a world somewhere else, if we fail, we just come back to Earth. If we stay here, and try not to screw up the Earth, if we fail, we all die.
I prefer option #1.
Thanks for the clearing up of info - my solar nuclear physics is better than my man-made.
However, my point was that people were trying to claim that saying "with fusion" was a cop out because we didn't have fusion yet. While that's true, He-3 is helpful for us in using fusion, and possibly developing it. He-3 is in pretty sparse supply on the Earth's surface (it does exist, but in low quantities - much worse than deuterium and tritium, as you know) - so experimenting with it is costly. Though unlikely, it's possible that experimentation with He-3 would uncover a method to actually make it work (very unlikely, but possibly not - the fact that He-3 has twice the charge of a triton can be useful in some instances - possibly magnetic bottling, where the same magnetic field strength will cause twice the containment force). Don't forget - virtually nothing in science has ever come out of theory before it's come out of experiment, so it's always useful to run them, even if you think you know the answer.
I didn't include numbers because, basically, numbers don't exist yet. As far as I know, no one has done a study on the potential environmental impact of solar energy exploding as an energy source. As it is now, of course, it's perfectly safe. The fact is, though, unless we use energy from outside the Earth, that energy was meant to go somewhere, and using it excessively means potentially having ecological side effects.
Another problem: solar power isn't continuous, so now in addition, we need an energy storage mechanism. Want to power the Earth with solar energy? You need one hell of an energy storage mechanism! Energy storage isn't perfect, so you'll lose a bunch there as well. Not only that, but you'll probably have to do it with something that's either consumable, or requires energy to initially create.
Additionally, don't forget that during the winter, a good portion of the Earth doesn't get *any* sunlight - or negligible sunlight. ("Sorry, Helsinki, but you can't have any power for about a third of the year.") No energy storage mechanism could possible store enough energy to power Helsinki for a few months, so now we'd have to have an energy grid across the entire world. Energy transmission incurs large transmission losses, not to mention the massive infrastructure cost and maintenance.
Solar power not only isn't feasible, it isn't environmentally sound, even using your numbers which are *very* generous (photocell efficiency is around 15-25%, not very much more) - 0.08% of the area of the Earth is around 36 million square kilometers. Regardless of whatever you do, those portions of the Earth will have drastically different properties than they were intended to, and will, in some way, end up radically changing the environment, I'm sure.
Unfortunately that's not really a wonderful argument (the first portion) - the amount of energy lost in slowing down and speeding up is miniscule on any decent sized trip. It can be large, but usually it is not that important. Drag dominates everything, by far. Friction is pathetic (remember, friction only generates a constant force, so you'd only need an engine to start moving, rather than to accelerate. On an airless planet, all speeds are equally efficient. Since it is distinctly known that there are "most efficient speeds" for cars, drag really must dominate.
You can immediately see how much energy it must take to overcome friction - just try to push your car with the brake off. It's not that hard at all. At highway speeds, friction is more of an annoyance than anything else. After all, in most cars, with the car in gear and the foot off the brake, the car will begin to move. Therefore, if it wasn't for drag, at highway speeds a car could *idle* and still move.
And as for the slowing-down/speeding-up argument, remember that the in-town/in-highway miles per gallon only change by a tiny amount - at most 30% or so, at least about 5%. Since slowing down/speeding up only occurs once on a highway trip, again, drag must truly dominate.
So, unfortunately, the -pure- energy efficiency of electric cars vs. gas burning cars may still be in question. My guess is that the energy efficiency award could ultimately go to a car, *with* an intelligent enough design, and also only in most situations. However, currently, with the piece-of-crap internal combustion engine located in most vehicles, an electric car nowadays will win out.
There is still, of course, the issue of pollutants, and as you noted, electric plant generation of heat. However, I would note that adding additional power plants, while significantly cutting down on global pollutants, would significantly increase local pollutants, destroying local habitats and doing much more -visible- damage. Therefore, to people, it may appear as if electric cars have done more damage than gas cars did.
Those tribes might get a bit freaked out when the moon slowly gets farther away as it eventually will. At some point, it may not even be visible in the sky for them anymore! Maybe we should go blow up a nuclear bomb on the moon to make sure things don't change for those tribes. (/sarcasm)
Things change. Life would be boring otherwise.
First off, this is definitely old knowledge. The existence of He-3 on the moon is completely well known and has been for a while.
The "combined with fusion" thing is not exactly a cop-out. What they meant was that using He-3 as a fuel for fusion can produce quite a bit of energy, and He-3 is a very useful catalyst for fusion. Why? Same reason that deuterium is beneficial - because you're bypassing some of the steps in the p-p chain (the process that the Sun uses to make helium out of hydrogen). Basically, you can lower the energy threshold of sustainable fusion reactors if you already have tritium, deuterium, and Helium-3 present, because now instead of reaching the energy threshold of just one reaction (proton-proton -> deuteron) you can reach any of the steps in the p-p chain immediately. It's similar to chemistry - you can speed up a reaction if you have some of the intermediary products already available.
Second comment: what the heck are people complaining about using the moon for energy? You think solar power is better? Really? You really think it's free? Just like wind and water power is free, huh? Solar power is great - on a small scale. Try to use it for the reasons you want to use it for - like powering the *world*, for instance - and you might have a problem. All that solar energy was meant to go somewhere - the air and the ground. There's a definite solar thermal cycle, and stripping out energy can affect it. On the scales that people typically use it for now, like powering lights or scientific instruments, it's fine. Even maybe for a few supplemental reactors. But if you honestly wanted to power the world with it, you better start realizing that power generation will always hurt the environment. Always. Period. End of story.
So, then, the answer is, why the hell do we care what we do to the moon? It's *dead*. It's static. It's unchanging. Study it for a while until you mostly understand it, and then you're free to do with it what you want. Helium-3's a good idea - very good in fact. And yes, when we run out, we move on to another planet. Is this a problem? No. These planets were static. They weren't changing. We're not *affecting* anything that was important to begin with.
Here's a bit of reminder before I get flamed for being an anti-environmentalist or something strange like that. Life is destructive. It's entropic. But who cares? That's the point of the entire friggin' universe.
Interesting scientific point. Entropy is mathematically identical to the concept that Shannon (yah, the modem guy) called 'information', and it's quite appropriate. Entropy is information - it's the universe saying "Something happened here." So when people say that entropy always increases, that's correct - because things are happening - information is being generated. Thermo tries to tell us that this is a 'bad' thing - they call entropy chaos, or disorder. That carries a connotation of evil or wrong, which is not right - it's simply a way of saying "something happened here."
So we have two choices. We can avoid energy use entirely, and calmly sit here on the planet, maybe migrate when it dies, and do nothing. Might have to destroy most of Nature too. Nature is rather entropic... eats up a lot of power and just turns it into heat. Or we can do what living beings were intended to do. Live. Use the fuel that the universe gave us - just, try to make it last as long as possible. Not infinitely. We can't live forever, and we shouldn't try to.
Bottom line - there's nothing wrong with using up resources. They're there to be consumed, or else they'll just sit there forever. The real goal is to use them intelligently. In my opinion, using a big rock whose entire job seems to be to act as an asteroid shield and a tide generator as a power source is pretty damned intelligent.
Illogical hand waving? Find the error in my argument and explain it, rather than claiming it's simply illogical.
I'm not claiming my doctrine is correct. In fact, I'm claiming it's not correct - at least, not completely. What I *am* claiming is that the claim of the person previously, which was that the collapse of the wave function can be explained by particle interactions, is wrong. Here's the kicker - he's using the same doctrine I am - quantum mechanics! This is *math* we're talking about here, pure and simple differential equations. Computers can solve them (pretty well, actually). Math has a right and a wrong, and it's not based on any complex that I have.
(Incidentally, I wasn't insulting the previous person - he claimed that everyone else was being stupid, and challenged someone to show that he was wrong. I took him up on that challenge.)
Finally, because flames don't particularly amuse me, coding is no better than physics in this regard. Look at Microsoft. Windows compiles. It seems to work. Is it a fact that it's well coded then? Yah. Right. If you think an uptime of about 4 days on average is "well coded". Not to mention the philosophical arguments as to whether or not microkernels or monolithic kernels are better, or any other piece of coding.
If you think physics is all about philosophy, you're quite dead wrong. Physics is as much about philosophy as computer science is.
And just to get my small flame in, you go right ahead making machines work. When you want more processing power than the speed of light allows, I'll just sit back and smile as you come crawling to me (or physicists in general). I do physics because I want to do more than make a few things better - I want to make *everything* better.
Learn the physics first, please. You don't exactly understand what they're talking about.
:)
Imagine an electron is in a mixed state, that is, it is not in a measurement eigenstate (i.e. it is not 'definite' what the result of the measurement will be). Now, *observe* the electron. I don't care how. Just make it so that macroscopically, the state of the apparatus is linked one-to-one with the state of the electron. Now, the question is, when you observe the apparatus, you don't see a superposition of eigenstates - you see one eigenstate. This is what is typically referred to as "the collapse of the wave function."
Your explanation would be "well, you scattered an electron or something off of it, and that changed the state and 'somehow' that pushed it into an eigenstate." Good explanation. Two points for trying.
Too bad you're wrong. Quantum mechanics knows how particles interact - they interact via the Schrodinger equation. You can do the basic QM for the apparatus/electron interaction. You do *not* get that the electron emerges in an eigenstate. (You couldn't. That would indicate a hidden variable theory, and Bell's inequality says that QM and a hidden variable theory don't work.) You get that the entire system is in a superposition of eigenstates.
This again leads you back to the previous problem. Somewhere, the wave function collapses. Guess what? We don't know where yet. We have no idea where yet. "We're working on it."
So, is there a mystery to it? Yes. Is there a *problem* here? No one's been able to find one - i.e., no one has been able to find anything other than philosophical problems with QM to my knowledge.
In conclusion, to sum up, in this case, yes, you're a total heathen. Sorry.
If you want a good reference to the philosophical issues regarding measurement and quantum mechanics, read J.S. Bell's Physics World, August 1990 article "Against 'measurement'" and the subsequent follow up articles in October, January 1991 and May 1991.
Oh, I quite agree- however, if you look at these papers, they're a strong argument for some form of peer-review on preprints. :) My personal favorite is the derivation of the second law of thermodynamics... note it closely and you'll see that it didn't require anything in the article at all. (Not to mention that it's a bit strange anyway, saying "F=E" and then in the next sentence saying "F=E-TS")
Note to all Slashdotters:
:)
They are NOT papers. They are preprints. Anyone and his brother can submit a preprint. They have NOT been peer-reviewed (nor are they likely to EVER be peer-reviewed) nor have they been published at all (nor are they likely to be published at all) because they're totally bunk.
xxx.lanl.gov (arxiv.org) preprints should not be taken as being fact. Hardly! Wait till you see something actually *published* and then you can take it with some conviction that it isn't crap science.
Do not confuse a preprint with a published paper.
Actually, it *is* a particle in the sense of a proton/neutron! What exactly do you think a particle is?
:)
A particle is anything which carries energy or momentum. Period. In quantum mechanics, we can model vibrations of a lattice as collective excitations across the lattice ("normal modes").
These collective excitations are called phonons, sometimes called quasi-particles. But they are particles - they are absorbed, emitted, recoil, and diffract.
Quantum field theory (welcome to hell, boys and girls... enjoy renormalizations) is all about this - now, instead of some particles being collective excitations, *all* particles are
collective excitations.
This basically comes down to a question of exactly what is a particle, which is usually
covered in a second-semester or first-year
graduate course. Particle does have a sort
of rigid meaning, but you can't revert to
classical thinking all of the time.
Plus you just have to get rid of that wave-particle duality crap. Waves are particles.
Ever stand in an ocean? Ever get hit by a
rather strong wave? (Not a crashing one,
those are wierd... welcome to yet something
else that physics can't describe yet) You
feel it, don't you? But it's a *wave*, not
a particle.
Simple answer: collective excitations of "X"
field where X is some quantum mechanical field
are particles.
Note that a graviton isn't a particle yet. We don't have a quantum mechanical gravity field yet.
Your confusion is in the definition of "transmission" and "reception" here. "Transmission" corresponds to the moment that the signal left the signal generator. "Reception" corresponds to the moment the signal arrives at the receiver. Any time inbetween is a totally different event.
.gif.
In this case, what would happen for any observer in the middle of the flight path of the signal - assuming that the signal left a visible trace (Assume it does, for the moment... say, a huge blue streak) - would be that he suddenly sees a blue streak appear, in the middle of nowhere, and radiate out, faster than light, racing towards *both* the reception *and* transmission points.
Where the streak arrives first depends on where the observer is. You can write a quick expression using trigonometry to derive the location where the observer sees the streak reach the reception and transmission points at the same time.
For an image which explains this situation, take a look at http://www.personal.psu.edu/~psa104/FTL
Yes, and no. MWI/Copenhagen have existed just
about as long as each other - since the beginning of quantum mechanics.
Probably the best interpretation of quantum mechanics comes from Roger Penrose, who taught a class I was in. Simply put, he said that we do not know enough to make any claims whatsoever as to the true nature of the Schrodinger's Cat problem. Which is true. We unfortunately still have several paradoxes to resolve before we can even approach explaining Schrodinger's Cat - the Quantum Xeno Paradox, for instance, which states that one can make an improbable state persist infinitely by continuously observing it - i.e., by making it continuously interact with its environment. This will tell us whether or not measurements actually do what we think they do - i.e., collapse the wave function. Currently the quantum xeno paradox favors quantum mechanics, but unfortunately the results can be easily explained away.
That's just the beginning of the problems facing the philosophical aspects of quantum mechanics. The other major hurdle is the use of the word "random". Einstein probably hurt us the worst when he said "God doesn't play dice," since dice rolls are random (more or less).
Quantum mechanics is -not- about randomness, or probability. It is about distributions. An electron in a mixed spin-up, spin-down state does not have a 50% "chance" of being measured in spin up. Quantum mechanics means *nothing* for
individual particles or systems. It only has meaning for large collections of indistinguishable objects. In other words, in the previous example, an electron in a mixed spin-up, spin-down state doesn't have a "probability" of being measured in a spin-up or spin-down. It'll be measured in whatever it's measured in. However, if you take a thousand of those electrons, on the average, you'll get 500 up,
and 500 down. Plus or minus 10 on both. Gotta love Poisson statistics.
*That* is the best interpretation of quantum mechanics - it's the same interpretation of statistical mechanics as well. The theory means crap for individual objects. Only large numbers of objects. Therefore, talking about "one molecule" of DNA is bunk. You need to talk about a large number of DNA molecules, all in the same mixed quantum state. Then, on the average, if their states are measured, then QM will give the right results. Not for each one. This whole "choice" thing and "quantum multiverse entering" is meaningless.
Babelfish is not a one-to-one translator, so there is information lost. Since its vocabulary is limited, multiple words may map onto one word in another language. This makes it impossible to reconstruct the original text, regardless of what you know about the program -in essence, Babelfish introduces 'noise' to the system.
However, I don't think this will inevitably fix things - the author here was talking about stylistic usages - such as quoting from sources, or common recurring words/themes - these won't be pulled out by Babelfish, though Babelfish may make it difficult to note certain patterns.
I agree with the method - I can usually recognize people online simply by word usage and punctuation usage. Punctuation is usually a total giveaway - for instance, I tend to use dashes a whole lot, and rarely (if ever) miss capitalization or comma usage (In real time chat, it becomes even easier, as you can tell roughly the speed at which someone types). You kindof "pick up" these habits after dealing with other people online quite a bit. This just takes that learned habit to a new level.
Curious point, considering that entropy *is* information, period - mathematically, they're identical objects, with information being the log of the distribution function, and entropy being the log of the partition function, functionally identical objects, as well.
Entropy is the universe's method for keeping track that interactions happen - no, it'd probably
be better said that it's a mathematical construction with no real physical basis. Truly, if you think about entropy on a purely physical basis, it would kindof seem like magic from a macroscopic point of view - from a microscopic point of view, though, it's obvious - of course you can't revert to a lower entropy state, because something *happened* to cause that entropy state, and that 'something' can't just be forgotten. But what if that 'something' could be forgotten - i.e., it's reversible, with no energy needed? Then the process was adiabatic- no entropy change - and no information gained.
But, in any case, to your point - I don't believe the problem Katz was talking about was unwanted information - but necessary information - i.e., survival information. Our brains are remarkably good at filtering out unnecessary information from our senses - however, people don't seem to be very effective at filtering out useless directed information. We learn naturally to ignore
constant murmur around a room. We don't seem to learn to ignore constant "Horrific shooting maims 3 in supermarket slaying" on the local news - people seem to grab on stories that have been hyped and overdone, leading to a false sense of the progression of the world - i.e., 'schools are becoming increasingly more violent' when evidence shows otherwise.
I don't think that entropy is information's Regulon- I think cynicism is. Eventually, when kids grow up in a hyped up society, we won't believe it anymore. Eventually, important information will find a way to breach the cynicism, or it is ignored and filed away.
I definitely go for videogame supervillains. Unfortunately they get to be a little too like their counterparts. Sephiroth (my main machine) is just pure evil. Kefka (our server) is psychotic, and every once in a while just does something completely random, then looks innocent so he can get something. (Swear!) Krelian (spare machine) is far more powerful than you could possibly imagine at first, and Ganon (laptop) keeps having the *same* problems, over, and over, and over... It also makes me wonder whether or not those random blips on the hub aren't the computers attempting to take over the world.
The mission is not to collect antimatter. It is to identify it. The entire idea is to try to see if the cosmic ray flux contains complex antinuclei from antimatter galaxies. They won't actually be 'keeping' the antimatter - in actuality, the antimatter won't even stop in the detector, most likely.
Actually, positrons have been found as well, and actually you answered your own question.
Antiprotons *are* antihydrogen - ionized. The chance of a cosmic ray nucleus not arriving at Earth ionized is virtually nil.
And the press release *is* misleading. The mission is to *detect*, not to collect, antimatter.
You can't "collect" antimatter - at least, not cosmic ray antimatter. It's moving too fast.
The way they determine if it is antimatter is they use a superconducting magnet to curve the particle's path. By measuring the path (via a variety of methods, I don't know what BESS uses) you can determine whether the particle is positive or negative. Then, you also use other techniques such as time of flight analysis, and Cerenkov light produced to determine the mass and energy of the particle.
This has actually been going on since the 1960s. This is simply the newest flight of BESS. The important mission for detecting antimatter in cosmic rays is actually AMS, which is to be placed on the Space Station in a few years. Since in space you don't need to worry about atmospheric background, AMS will (hopefully) be able to see antimatter at a lower level than anything else.
Also: Antihelium that would be detected by this *would* have a charge. The possibility of finding an antihelium atom *not* ionized is *zero*. Not close to zero, just plain zero. (Okay, maybe it's like 10^-100 or something like that. But it's zero.) What they're looking for are anti-alpha particles.