You mean like the harsh complete lack of environment in "deep space"? Acoustical and vibration testing for riding around in a hard vacuum, surrounded by nothing? Are they worried that the astronauts are going to put on smash rock at 120 decibels with overdriven bass and accidentally shake the capsule apart?
Some copy writer for the press has been watching too much Star Wars.
Or maybe, just maybe, the vibration testing is for doing things in near space, like flying through the atmosphere while landing...
Or we can go even further and argue that we cannot even be sure that the external universe exists at all, since all your knowledge of it is "in your brain", which might not even exist since your knowledge of your brain could be as false as anything else.
Given, then, that we can never be certain of anything concrete about the actual Universe (except that it exists and isn't empty, something exists even if it is only your perceiving mind -- whatever that is) we can forget about "proof" and "certainty" and instead pursue plausibility, or probable knowledge (following in the footsteps of Richard Cox and Edwin Jaynes). In this case the Bayesian estimate for the probability that the Universe would still exist after your brain dies is "nearly certain", on a logarithmic scale (Jaynes proposes the use of decibels to describe the approach to certainty of either truth or falseness of any proposition, since most of what we know is known as "almost certain truth" or "almost certain falsehood", not certain truth of falsehood.
Your total universe almost certainly does not exist only in your brain. The mere fact that you have a referent to something called "your brain" that we all understand is very, very strongly implicative of the existence of an objective external Universe of which your brain is just a tiny, transient part.
Now, don't bogart that joint my friend, pass it over to me...;-)
Or it my be better put that -- given the infinite number of possible ways reality might really be underneath it all, including string theories, 1+1 dimensional space splitting into 3+1 dimensional space, every religion you can imagine, world of warcraft universe, the Matrix -- it is just fine for physicists and metaphysicists to speculate all they like about this sort of thing and other invisible fairies such as magnetic monopoles, Higgs bosons, dark matter and energy, and gravitons, but humans with a fair dose of common sense will wait for solid evidence to support even the most attractive of these theoretical ideas, and extremely solid evidence to support any of the relatively implausible ideas, such as (pick the religion of your choice, doesn't matter as unless it involves pirates and pasta it is highly implausible).
As far as physicists (theoretical and otherwise) and weed is concerned, it all depends on when they went to school. Physicists in grad school in the late 60's through the early 80's have a fairly high probability of having smoked weed anywhere from once ("without inhaling") up to living with a more or less perpetual nonzero concentration of THC in their blood. I rather think that the probability dropped some in the 80s and 90s, and I don't feel qualified to comment on the 2000s so far. I doubt the relevance of this to the issue at hand, though. There is substantial evidence in the form of several paradigm-shifting revolutions in the way we think about nearly everything since the Enlightenment and Newton that it is a capital mistake to limit your imagination to only the accepted and boring and simple and already consistent with experiment, even as it is an equally great mistake to completely divorce your flights of imagination from empiricism. Physicists quite correctly span the range from complete divorce, a.k.a. "mathematicians" through various flavors of theorist through various flavors of experimentalist right up to empirically grounded engineer. I've been to string theory talks where the theorist spoke about spaces with 8192 dimensional spaces -- with a straight face. It's all good clean fun as long as you don't try to pretend that this should be taken as probable fact unless and until the theory is empirically grounded and shown to have both explanatory and predictive value that isn't easily obtained without it.
IIRC microwave ovens were "discovered" when soldiers learned that they could put things like hot dogs on sticks and dangle them in front of radar dishes in WW II and cook them in a few seconds. A radar technician who noticed that a chocolate bar in his pocket melted when he was working on an active radar had the bright idea of confining the microwaves and using them to cook food. Hence the early Ratheon "radar range".
So it's not so crazy that someone would learn to reverse engineer (in a sense different from the usual one:-) a microwave oven into a radar unit, or into an information transmission link. The biggest catch, I imagine, is the need for near line of sight (so you'd need to be very high up or very near the border) and a suitable receiver on the other side. Also the fact that moisture attenuates the frequencies used in microwave ovens by design, but I imagine that's less of an issue in Libya.
You mean like the gpg signing not just kernel but all rpms have had as default for many years now? And while buffer overwrite attacks are certainly not unknown in linux, good programming practices in C plus many eyes on the source code make them way less common, especially in privileged code, in linux. And when they occur, they get patched almost instantly, often within a matter of hours of when they are first announced, and with either yum or apt are often distributed to the entire universe of installed linux systems within 24 hours of the announcement.
It's shooting ducks in a barrel to compare that with the six month lag that Microsoft not infrequently left critical tools like Explorer with wide open bugs in it, unpatched, over the last decade or so. Seriously. Perhaps Microsoft has at long last changed its ways, and is suddenly ubersecure and will be aggressively maintained. To be honest, I hope so, because God knows its been chronically insecure, a bit of a security joke, as long as I can remember, which is back to 1982 and my 64k motherboard IBM PC.
Sure, some of the security problems have come from it being marketed as a "personal" operating system with little permission regulation and splitting of permissions, but sorry, that's a bug not a feature. And most of its problems have come from its enormously slow and cumbersome and delayed history of fixing problems, even really, really serious ones. A cynic would say that they only started to invest money in making this better when they began to actually lose business because of their abominable reputation in the marketplace.
To be honest I hope that they've fixed it so that it is more secure. I have spent many, many utterly wasted days over the last fifteen plus years fixing Windows systems that have become hagridden one way or another, and there are places you can't use anything else because the software you want to run only works on Windows, so you have to apply AV, cross your fingers, and pray, which worked really well except for the finger crossing and praying and there I'd be, trying to salvage data and do a complete reinstall -- again. If you are forced to manage a heterogeneous network with mixed lin and win and whatever, weak links suck and Windows has always been the weak link. I'd be thrilled for that to change -- but it was announced that XP was going to be the "secure Windows" too, and look how that turned out. Better, sure. Secure? Please.
So I'm forced to judge Microsoft on the basis of a mixed personal irritation and laziness and cost index amortized over decades. Cost: high, now and before. Advantageous to the lazy? Not. I spend far longer configuring a new Windows install than I do a linux install, and it is much harder to automate (where in linux it is trivial and doesn't even require much in the way of local media any more). Irritation index? Don't get me started.
Ah, you mean that they've finally cleaned up their operating system, and if their users get cracked using Windows 7 it's their fault. Sure. I understand. The last 15+ years are now irrelevant. I hereby declare that they never happened.
To be fair, I haven't yet really tried Windows 7 much, because I have all of these leftover XP licenses and XP actually works and runs well on older hardware and under VM software. Windows makes a lovely application on my Linux box for those few times when nothing else will do. But I'm thrilled that the thousand or so of the "world's best programmers" that supposedly work for them finally actually achieved the level of security that Unix in general managed back in the 90's. I'll be sure to tell my kids that if their Windows 7 or Vista systems get cracked that it's their fault, too. That way it won't be my responsibility to clean up the mess.
Only the idea as described in the article. The questions I'd have for the very different method you describe is how you plan to find a ~1 kg chunk of mass between 1 and 10cm in size and hit it with a laser. That's something like 0.002-0.02 arcseconds, right? Pretty damn good shooting required (NASA or not) and you also have to deal with the spreading of the beam at an oblique traversal of the atmosphere, although I have no immediate sense of the order of magnitude of this. However, 0.02 arcseconds of spreading (while making it more likely to hit) also makes the intensity on a 1 cm target go down by 100 (for a 1 cm beam).
I don't completely disrespect the idea; I think that the idea as described in the article was out of kilter with reality by orders of magnitude, because light pressure is really, really weak. It seems that you would agree with this. Perhaps what you describe might work, although then I'd still suggest that moving the orbit of the threatened satellites with light sails is a more plausible idea -- at least there one can get radiation pressure nearly all day and optimally direct the thrust, and one can be certain that you are hitting the target. How are you going to even know you are hitting the target? A 1 cm ball, even white hot on one side, 0.002 arcseconds across is going to be pretty much invisible...
Actually yes, repeatedly. I've even published papers on nonlinear optics, although that is as irrelevant as your comment. What specific parts of the results are supposed to surprise me?
Wait, I'll go upstairs and get a laser. There. Yup, fortunately it still works (my sons tend to like to play with them and run down the batteries). Lens, lens, I need a lens. Wait! I know! My reading glasses are an actual lens! Experiment: Shine laser on wall no glasses, a sharp point with the usual spackle. Shine laser on wall through lens -- OMG! How SURPRISING! The dot is spread out. Shine it through at an angle -- ASTOUNDING! The dot is smeared out sideways!
Boy, for a second there you had me worried! I thought that perhaps "laser light" wasn't electromagnetic radiation after all and didn't obey Snell's Law (at least approximately) when it passed through dispersive media! I would have hated to have missed that when I taught graduate E&M courses...
So now that we've established that I have indeed run a laser through a lens -- again -- and that lenses or dispersive media in general do in fact bend even laser light (which is differentiated from the usual hot random source kind only by being moderately coherent but otherwise behaves pretty much like -- light) did you actually have a point somewhere in there, lurking, waiting to be made? As in travelling through a thousand km of atmosphere on an angle through a differential gradient in density won't bend laser light, it only bends the ordinary kind enough for pointlike stars to visibly twinkle on a clear night and thereby limit atmospheric resolution through earthbound telescopes? Or were you wanting to assert that the atmosphere is incapable of deflecting light in general the 0.2 arcsec necessary to miss an order 1 m object at order 1000 km range? Or that the smearing of the beam caused by going through the curved differential gradient obliquely won't cause it to be larger than 1 m in size before it hits the target? Instead of being mysterious, try making a point.
The light from the sun seems irrelevant, as it's not purposeful, though I imagine they would have to take it into account when calculating when and how (and whether) to aim their lasers.
Interestingly (I did some more looking at this and found some articles via Google about drag forces) the state of the sun is very important to the drag force that eventually does deorbit the satellites. My point was that sunlight at low earth orbit has an intensity of roughly 1.4 KW/m^2, which is comparable to the laser intensity they are talking about, and tends to be ignored even by the people that compute this drag (suggesting that either they -- also NASA people -- are foolishly ignoring an important contribution to the overall deorbiting force mix or that it is several orders of magnitude smaller and hence negligible in the grand scheme of things. Personally, I vote for the latter. Total radiation force is order of total power divided by c in both cases independent of how it is concentrated or not, and over a day the total force exerted by sunlight is likely to have a far greater effect than the total force exerted by a laser in the two hour window that they have some sort of angle -- and I suspect that the drag force itself is greater than either one, probably by orders of magnitude (that's what I was trying to figure out by looking at the articles). But even without the articles, we can do a Fermi estimate. It apparently takes order of decades to de-orbit a satellite from e.g. 500 km due to drag forces alone, with (of course) an. accelerating degradation as it sinks down into the atmosphere. Decades of a small force accumulating to hundreds of km/sec delta-vee for large massive objects, where (say) three decades is basically a gigasecond.
Once again F = ma, and a = \Delta v/\Delta t \approx 10^3/10^9 = 10^-6 m/sec^2. We therefore expect the average drag forces acting on a smallish 100 kg satellite to be around 10^-4 N. Compare to 5x10^3/3x10^8 = 1.67x10^-5 N from the laser, assuming no attenuation etc and it is indeed an order of magnitude smaller (and ditto for the direct force of sunlight), probably several orders of magnitude smaller from 250 km on in given an exponential drop in density and hence drag force with height. Again the drag force acts 24x7, the laser for a couple of hours a day, max, on at most twelve objects a day. On the same 100 kg object, that accumulates \Delta v at order of 10^-3 m/sec/day (multiply by 10^4 seconds in two hours, divide by 10^2 kg). A millimeter per second per day. Doing a viral estimate of the change in orbital radius, that should result in a change of around a meter in orbital radius per day, a result not incommensurate with the 10+ meters per day Fermi suggests that orbits change, on average, due to drag forces (assuming decadal decay times). A meter plus per day makes the scheme borderline plausible.
As for ideas any freshman could shoot down -- you have heard of SDI, right? And religion? Scientists are perfectly capable of proposing things and the government is perfectly capable of spending large sums of money on the proposals even when simple computations suggest that they are implausible, and humans in general are capable of believing almost anything that "sounds good" to them. If I were a reviewer of the proposal, I'd want to see the actual computations that show that they can a) detect a piece of space junk on a collision course with a LEO asset; there's so much out there that they have to use statistical mechanics to estimate the probability of collision at this point, and not all of it is of human origin; it comes in a wide range of sizes, reflectivities, and material compositions. b) identify its orbit precisely -- and I do mean precisely, to within centimeters, while it is being slowed by drag (possibly as it tumbles), sped up and slowed down by the solar wind and solar radiation force (again in an unpredictable and even chaotic way), and even is bounced around by geomagnetic effects (especially if it is a conductor) a
Sure, but what's surprising about that? Peter Norton was more than a bit of a tool back when he wrote bad columns in PC Magazine and sold "Norton Utilities" on the side. I'm sure the software is no longer being written by Norton, but it has questionable roots.
One question I've never been able to answer to my own satisfaction: Why does Microsoft allow antivirus companies to live? This is so antithetical to their own standard business practice -- if somebody makes money on it, and it is software, clone it and take over the market. Yet they don't either clean up their operating system's act by actually making it semi-secure or make their own antivirus software, something that really does seem as though it should happen at the deep OS level. Yet antivirus and antispyware companies flourish. I don't get it.
No, they got caught. Repeatedly. For example, on the browser issue. They've been in court in a massive antitrust case that in a just world would have resulted in them being broken up. One can go down a list of their major, massive, ethical violations and questionable business practices (all of which have been massively successful in killing off its competition). Take Borland, for example -- the actual inventor of the IDE (good old Turbo Pascal, $45, on the IBM PC). Take Lotus. Take Wordstar and Word Perfect. Take the vast range of young entrepreneurs who created massive markets and amazing new products in the early days of the PC, only to be systematically subsumed and driven out of business as the company that made the operating system co-opted their ideas, cloned their products, changed the operating system and/or compiler so that their products broke (while the Microsoft versions, developed after all by the same people who were changing the OS, didn't) and then using absolutely classic FUD techniques to win over first 1/2, then 2/3 and eventually all of the market. Take OS/2 (oh, wait, you can't, because of Microsoft's "ethical" behavior). Take their unit pricing that more or less forces all vendors of PCs to offer only Microsoft as the default preinstalled OS choice if they plan to sell any PCs with Microsoft operating systems preinstalled, in a marketplace that is so price competitive that the price differential is near certain death (which means that you pay the "Microsoft tax" even on a computer you buy to install linux on).
Why put up links to articles on MS's unethical behavior? I've lived through it. So have lots of/.'ers. I can even remember a brief period back in the early to mid-80's where it actually was fairly ethical -- Microsoft was once upon a time the good guys, the provider of an admittedly mediocre but nevertheless adequate operating system on a marvellous "new" invention, the IBM PC, the machine that let individual humans get their own computer and fight against the massive power and enormously exploitative pricing of the giant big-iron computer manufacturers, the machine and OS that unleashed a flood of entrepreneurial activity as anybody could program new software for it (and thousands of people did) and hope to make a fortune (and thousands of people did).
Then they got greedy. Why should all of those other people make fortunes using our OS and compilers, they thought? We have all of this money, and all of these programmers, and this marketing channel. All we have to do is wait for people to have really good ideas, and then steal them! Integrated tools? Wow, good idea! Let's steal it! Spreadsheet? We can write one of those, too! Word processor? Piece of cake! Games? Too much trouble -- we're making too much money as it is, let's just start buying up companies, or parts of companies.
The upsurge of the Internet took them by surprise, of course. TCP? IP? Open standards? HTTP?
Ever since they have been trying to somehow lock it down with proprietary and/or patented technology in some "killer app" way that would make all of its pesky competitors roll over and die, but not quite die, if you know what I mean. They got a big scare when Apple nearly went belly-up -- if it had died the rest of the way they might well have been broken up in the antitrust suit, but fortunately all of the big companies had pension funds that were heavily invested in Microsoft stock, and so nobody really wanted them to lose. It suits them to have "competition", enough for show.
Linux is, and has been for some time now, a dilemma for them. In their world, things like Linux shouldn't be able to exist. No matter how cost-effective and efficient Microsoft's product development and support is, it can't compete with free. It also made a living for fifteen years by hiring the best and the brightest programmers in the world, until its practices became s
a) The article methodoology explicitly claims to be using light pressure only.
b) If they can actually hold a 5 KW laser on target at a single point on the object it might heat it up to where ablation occurs, and yes that would produce easy orders of magnitude greater (if still tiny) thrust. However, I don't think they can come close to achieving this and they'd have to work quite hard to convince me before I was willing to drop $50-100 million dollars on the experiment. Atmospheric ripple and other sources of vibration would -- IMO -- make that dot bounce around all over the place while conductivity spreads the heating out. I'm not completely convinced they can hold it steady "on" an orbiting object at all, although this is where they would indeed be spending fifty million or more dollars for every million they spent on the actual laser. How would they even know if they are hitting it?
In star wars type lasers, they (I'm pretty sure) shoot very brief, very high power PULSES to deliver a significant amount of heat in the very small time the laser will hit "somewhere" on the target. That might work here as well, but that isn't what the article is advocating.
In the after-article article they make it clear that they're not trying to destroy the objects (which they cannot do in any event), and that they recognize that it would take decades to actually knock something out of orbit (a vast underestimate -- try centuries). They allege -- and I'm still having a hard time seeing it but it is barely possible -- that they can divert the orbit of something enough to prevent a collision. The after article also makes it clear that the actual cost of building a laser system to do any of this is orders of magnitude more than a million dollars -- that's the cost of just the laser, not the targeting system, which has to be just as accurate and stable as any star wars antimissile laser device. They also clearly state that they are relying on light pressure, not outgassing or heating in general.
Changing an orbit enough to cause the junk to miss by meters instead of hit something is at least in the realm of the possible, given that tiny changes in orbital velocity can make large changes in orbital position over a long enough time base. Large at least compared to the size of a space ship.
I'd like to see the actual arithmetic that they use to justify this, though. The piconewtons from the laser actually have to be compared to things like the piconewtons being exerted by the light pressure from Mr. Sun at this sort of scale, and the sun shines on them all of the time. The forces are likely within an order of magnitude of each other, and are comparable to the extra force you experience when you lie down on the beach at noon on a sunny day.
I commented elsewhere on the actual numbers, which show quite clearly that even a 5 kw laser would exert at most completely irrelevant forces on any object large enough to actually see from earth and hence target -- accelerations on a good day of 10s of microns per second per year of radiation pressure. Having RTFA and noted all of the corrections by the authors (of the idea, if I understand things correctly) it is still an enormously stupid idea. What part of piconewton scale forces is difficult to understand?
I give this one as an assignment for my intro physics classes -- suppose you have a megawatt laser with a beam 1 cm^2 across and mount it on the rear of your spaceship to use as a drive. Wow, a whole million watts of power! Surely that will provide the ship with all kinds of thrust!
Sure, if all kinds of thrust is a few micronewtons.
You'd get more thrust -- and probably more net delta-vee for any acceleration time you are willing to wait -- if you simply took the laser to the door of your capsule and threw it, as hard as you can, away.
What? You insist on doing arithmetic? Something like P = I/c (within a factor of 2) for the radiation pressure exerted by light? So that if we make a very generous assumption of a kilowatt in a single square centimeter, we have 10^3/3x10^8 \approx 3 x 10^-6 Pa. We multiply by 10^-4 square meters (one square centimeter) and get 3 x 10^-10 Newtons. Take into account attenuation in the atmosphere and the fact that the beam is wiggling all over the place because of atmospheric thermal ripple and lensing, and you would be lucky to exert 10^-11 Newtons per kilowatt per square centimeter of laser beam.
If our supposed space junk is travelling in an actual low orbit, it is travelling at roughly 7 km/sec. Let's assume that it has a mere 10 kg of mass -- if it is much smaller just finding it from Earth will be difficult, let alone hitting it. Lessee, F=ma, so we can give it a maximum relative acceleration of a whopping 10^-12 m/sec^2! A year, on the other hand, has a mere \pi x 10^7 seconds, and of course we can shine our laser on the object at most a few hours a day -- again, a duty cycle of 10^7 seconds/year would be enormously generous.
This means that we can -- over a whole year -- change the velocity of the junk by 10^-5 meters/second! That's right folks, you heard it here first -- ten microns per second per year of thrust with a 1 KW laser beam 1 cm across, and downhill from there in nearly every direction.
Of course this is still wildly optimistic. The problem is that we are exerting the thrust on the object from underneath. This is more or less at right angles to the direction of motion, and hence does very little to speed it up or slow it down. In fact, pretty much nothing. If we wait until it is directly overhead to hit it, we get the cosine of a nearly right angle as a transverse component and can only fire on half of the overhead pass before we are hitting it from the rear and speeding it up again. If we fire at an oblique angle, to get a good dot product cosine with the direction of thrust and direction of motion, we have to go through an equally oblique layer of atmosphere that both bends the laser beam (making it effectively impossible to hit the target) and attenuates the kilowatt still further (reducing efficiency at about the same rate the dot product improves).
If the material were highly ablative, and if we could hold the beam steady enough to actually heat the object to where it boils, we could get some real thrust. Even a thin layer of actual reaction mass being boiled off of the surface would exert orders of magnitude more force than a perfectly reflected laser beam. But even orders of magnitude more thrust would almost certainly not suffice to slow the object enough to in any possible drug-addled, hallucinatory Universe make this an economically feasible, intelligent idea.
Now I know who was using the cocaine found at NASA today. Whoever it was that dreamed this one up.
You don't think that their monster rescue effort is to try to save Godzilla, do you? Could he -- even he -- have been injured in the 8.9 earthquake? Could Mothra have hit him with paralyzing sound waves as he surfaced?
Although it would be a good, clean solution to the meltdown problem, wouldn't it..;-)
Indeed. In fact, this is clearly the same plant that he once ate the core of in order to activate his glowing back scales and enable him to blast his foes with radioactive fire breath. I'm guessing that they just didn't repair the cooling system very well -- but then, it was in pretty bad shape after he ripped it apart.
In fact, the quake itself was probably Godzilla breaking free from his watery tomb. Look out Tokyo!
Right, so in this particular zero-sum game, the only way to be certain not to lose is to use a true-random (or as close as makes no difference) generator to select your moves, e.g. roll a die, 1 or 6 is rock, 2 or 5 is paper, 3 or 4 is scissors (first order correction for the weight of the pip cutouts). No matter what your opponent's strategy, this leads to a draw in the long run.
To win, you have to observe your opponent's sequence for correlations and exploit any patterns you discover. Indeed, I've often thought about writing a NN to play the game on the latter basis, perhaps fuelled by a library of typical human correlation matrices. However, if the game is played mathematically, the player that uses any proactive strategy loses. Strategy basically means "nonrandom move patterns", and any systematic deviation from randomness can be detected against a background or null-hypothesis random play (in time) and exploited, any algorithms used to exploit apparently nonrandom play can be detected and exploited.
Great video, good argument. I've seen the argument before, of course, and find the lipid-bilayer bit to be moderately convincing. However, it is only one of a moderately long string of proposed models or partial models, obviously in the "replication first" rather than the "metabolism first" camp. Wikipedia (as always) has a list of at least the primary (named) propositions. In particular the sea-foam (bubble) argument is almost identical to this one, with an even more generic source of compartmentalization and different sources of free energy.
The only real problems that I have with this or the other models are:
* There are still a lot of models! There is still not good agreement on even basic chicken/egg things like metabolism/replication. The reason there are a lot of models is that there is not a lot of compelling evidence favoring one model over the rest. As a physicist/outsider, I find the replication first argument slightly more convincing because I write genetic optimization code and am aware of the enormous power of a good GA, but there's a whole lot of chemistry that is not, actually, reducible to nifty dots in a movie that say "this is what happened" -- not without evidence or actual numbers and experiments to support it.
* The good thing about the video is it shows a plausible chain (relying heavily on the aforementioned power of a GA to "discover" favorable proteins which are then first weakly conserved, then more strongly conserved as some of the proteins discovered improve conservation) from stuff to primitive cells (with metabolism one of the discoveries along the way to eventually free cells from their volcanic vent). The bad thing is that there are a whole lot of probabilities in there that the video implicitly asserts are essentially unity over specific ranges of time, without anything vaguely resembling proof! Or even a mathematical argument. It basically proposes that if you set up a heat source in a soup with roughly the right local chemistry and wait some unspecified time, the soup will have a macroscopically relevant probability of spitting out a living cell with both metabolism and replication capable of living away from the heat source. The problem here is obvious -- that is a serious claim in statistical mechanics and chemistry, where big numbers/small numbers abound that can easily be so big/so small. A sound computation of the probabilities might end up with many lifetimes of the visible Universe per (e)vent, so that only by having a visible Universe filled with vents does one get a finite (but very small) number of "wins". Or, as you seem to wish to believe, it could happen with near certainty around any vent given a mere million years of cooking, so that life is essentially certain on any planet with vents and the right chemistry and temperature and pressure ranges available "somewhere" for geological times. The same objection holds for the other models -- they show some greater or lesser degree of plausibility without having anything like a computation of the actual probabilities beyond hand waving.
My argument is still largely unchanged, as it is model independent. If life is so likely as to be nearly inevitable, then life abounds in the galaxy and has for some ten billion years. It is not then implausible that life has evolved to take advantage of unique niche environments such as comets, moons, gas giants; it is not unlikely that life seeds the stardust leftovers from the destruction of life-bearing solar systems upon the death of their sun. The rarer abiogenesis is, the more likely it is that the life we observe is the result of nucleation elsewhere followed by transport rather than local nucleation. For a wide range of probabilities assigned to the event itself, we would most likely be descended from interstellar hitchhikers from genetic stock that might be ten billion years old, and even in the case of high local probability there would be something of a race between the evolution of
I think that the argument would go something like this: The Universe is 13.73 billion years in its current post-bang Yuga. Life can arise on any planet formed out of supernova remnants of a second or third generation star. There have been planets so formed for at least 10 billion years, probably longer (since at least some large, short lifetime metal rich stars would have been formed after the first very short lifetime supergiants went nova). Current estimates for the numbers of third or fourth generation stars with planets with the building blocks required for the formation of life are in the hundreds of millions to billions, over most of the last 10 billion years. If life arose on any planet in the Milky Way Galaxy some 9 or 10 billion years ago then natural processes from supernova to solar wind could easily have seeded the interstellar gas clouds with spores, spores that accrete along with everything else into the masses of matter that eventually collapse into a new star. Any of these life-bearing packages that happens to fall into a suitable environment on a newly formed planet can short-circuit the abiogenesis route for all or most planets formed in the Milky Way after the first few managed the trick.
The reason this is plausible is simple. If abiogenesis is indeed likely, then it is likely that it happened long ago and that traces of life can be found throughout the Oort cloud and beyond, because there are literally billions of years for it to cross the interstellar distances at the speeds of outgoing shock waves from supernovas and outgoing solar wind. In that case it might be a race, but fully formed organisms preserved in comets and other leftovers of leftovers of exploding star systems would have a huge advantage over local organisms that appeared from abiogenesis, which would be extremely primitive (and hence vulnerable) for a time.
If abiogenesis is in fact unlikely -- and of course we have no explicit model for abiogenesis that is yet accepted as being particularly plausible or probable in the sense that it is well supported by either evidence or even good seat of the pants statistical models or computations, so it might well be rather unlikely -- then even if it is unlikely that life arose on Earth (say, one in a million) the Galaxy as a whole has probably had tens to hundreds of millions of shots and life has arisen tens to hundreds of times, and every life-bearing planet very likely sheds "life" into its galactic vicinity at some nontrivial rate, especially in catastrophes such as when it is struck by an asteroid or blown away.
I therefore think that the meteor evidence is highly intriguing. To be truthful, I'd think it very odd if meteors and comets and dust particles from the Oort cloud on out did not have evidence of life -- that would suggest that life is somehow unique to Earth, which is most improbable. A chain reaction spread of life from one or more nucleation points that spontaneously appeared in a very large sample space indeed seems at least as plausible in the worst case, and far more plausible overall, given a state of near complete ignorance about the abiogenesis process itself.
Of course this could change -- somebody could come up with an evidence-supported model for abiogenesis, or a computationally plausible mechanism, or demonstrate it in the lab (at which point we could compute the probabilities a bit better). Or we could start to find evidence of life in all sorts of rocks that have never been anywhere near the Earth, once we manage to get out there and visit them. Or a big meteor shower could give off green light that blinds everybody who watches it and the next few days these big tree-people with sharp spiky things could sprout up and start eating people. Evidence, in other words, should be our guide here, not a personal bias towards local abiogenesis versus abiogenesis long ago and far away. Life is probably around ten or even eleven or twelve billion years old in the visible Un
A more interesting question is what will happen if they don't prove supersymmetry and fail (once again) to find the Higgs Boson, and in fact find "nothing particularly interesting" (perhaps beyond insight into the quark-gluon plasma, which is already forthcoming) all the way out to its maximum energy across all experiments.
Lack of evidence is not evidence of lack, but it is worrisome. It leaves open the possibility that we are off on completely the wrong foot, that reality is really nothing like our models, and we might have to go looking for new physics to consistently explain things like particle mass and gravitation and cosmological deviations from gravitation currently wrapped up in the "dark matter/energy" hypotheses.
Come to think of it, we might learn just as much from failure as from success. As usual. Even if it is a very expensive failure, compared to the knowledge gleaned from it.
Your curve clearly ends with an artifact in both quantities plotted caused by the fact that it is averaging zeros from beyond the end. You can't smooth right up to the present!
Look at the actual data! The sun has just come off of a stretch of four out of five cycles that are basically the among the most active on record or inferred by proxy in the Holocene. There is a clear dip/levelling in temperature in direct correspondence with the relatively low cycle across the 60s. The last solar cycle was not significantly lower at peak than the two immediately before it, certainly not enough to conclude that we should have cooled without knowing and quantitatively understanding the mechanism by which the earth cools during periods of low solar activity, which is, of course, when actual solar irradiance peaks! In other words, when the sun has no sunspots, it is actually slightly brighter and one would expect (if anything) warming, although the fluctuations in brightness are a trivial fraction of a Watt/m^2. This is why the primary climate models ignore solar variation as an important driver -- they cannot see how it works.
The other thing that you persist in wanting to do is look at the decadal scale changes as significant. I repeat -- until you can predict accurately how the Earth's "equilibrium temperature" (the temperature it is being driven to by the ongoing mean balance between sun coming in and heat going out) in an enormous system that takes in heat here, caches it there, circulates it from here to there, and does all of this in an environment where how effectively it gains or loses head depends on circulation patterns that appear and disappear on a multi-decadal timescale you have no idea what temperature it "should" be with or without CO_2.
However, you can easily rectify the situation. Extend the base of the very plot you built to 10000 BCE, along with CO_2 (which does indeed vary synchronously with solar state and temperature, with a decadal lag -- as the oceans warm they give up massive amounts of CO_2 as the complex thermal equilibrium concentration shifts). Then just mentally try to a) argue for high sensitivity -- global temperature takes decades -- multiple solar cycles -- to reach equilibrium. We were probably still in a warming phase in the last solar cycle in the sense that the "true equilibrium" temperature was warmer than the actual temperature, given the state of the sun. Also bear in mind that in any eleven year cycle local events in the chaotic cycle can confound any simple prediction. Isn't that at the heart of the CO_2 argument, after all, given that it is a terrible proxy for temperature over any multiple century range selected at random out of the last thousand years? For a single example, last year we had a vast bolus of methane -- and I do mean vast, cubic kilometers -- methane made up about 40 percent of the leaking crude by mass -- released into the atmosphere. Methane is a greenhouse gas over 20x as powerful as CO_2 at trapping heat, and it has a long half-life in the atmosphere. Methane from the Gulf spill no doubt blanketed a significant fraction of the Earth's surface in the vicinity of the spill as it was carried by the prevailing winds, producing the same sort of local warming that affects our cities and airports (with CO_2 producing planes constantly taking off and landing, often right above the primary weather stations that are so conveniently located there). Did this confound the lowering temperatures one might have expected given the volcano and slow/low solar cycle? Who knows? What matters isn't any single year in any event for this very reason.
But we'll see, very soon. The sun is rising what will probably be the lowest peak in over a century. The Earth has plenty of heat stored up from the heating phase, and of course there will be a lag and significant fluctuations as its chaotic head delivery system self-reorganizes, but by the end of this
As long as "a moment" is considered to be (say) 25 to 50 years and doesn't involve the creation of an easily exploitable global carbon trading system that would be corrupted into something far worse than the oil multinationals (and would probably somehow end up being controlled by them), I'm fine with that. There are plenty of very good reasons to build renewable energy resources and energy resources that don't involve burning a limited and valuable resource; if we'd spent the $500 billion or so that Iraq has ultimately cost us on massive solar even at a loss we would be more or less energy indepedent already, and because investment on that sort of infrastructure has a stimulating effect on local economy and prosperity, we would have actually made several trillion dollars in ROI instead of losing a trillion and a half or so in an economic collapse. If Obama could stop sitting on his hands and say "screw AGW, its an unproven hypothesis and we're not going to participate in carbon regulation and all that, but we are going to begin the next great science and technology project with the same dedication and investment of resource that we used to develop nuclear weapons and put man on the moon -- let's budget $50 billion dollars (or more) a year into direct subsidy of the construction of GW scale renewable power" then in ten years or less nobody would care about oil or carbon.
We could then use our new resources to stay moderately warm in the coming Maunder Minimum, and maybe forestall the gigadeath that will likely ensue if early frost starts coming regularly to the great granaries of Russia, China, Canada and the US. Which could happen extremely quickly of we enter a true grand solar minimum over the next two cycles. Warm is good, actually. We like warm. Warm permits crops to be grown, people to be fed, energy to be conserved, while we work on dropping the world's population without war, disease or genocide. Cold, on the other hand, would be a disaster beyond your imagining, and cold (if it comes) will strike quickly -- on the timescale of a decade or two, not over 100 years. Fear the cold.
This is part of the sheer evil of the IPCC's politicized abuse of the scientific process. We should be looking at all the hypotheses, even ones that are diametrically opposite to what we think is most likely to happen, as long as our knowledge of the science is uncertain. If we get cold after preparing for "certain" warmth, this will no longer look like a game.
Slashdot Mirror
You mean like the harsh complete lack of environment in "deep space"? Acoustical and vibration testing for riding around in a hard vacuum, surrounded by nothing? Are they worried that the astronauts are going to put on smash rock at 120 decibels with overdriven bass and accidentally shake the capsule apart?
Some copy writer for the press has been watching too much Star Wars.
Or maybe, just maybe, the vibration testing is for doing things in near space, like flying through the atmosphere while landing...
rgb
Or we can go even further and argue that we cannot even be sure that the external universe exists at all, since all your knowledge of it is "in your brain", which might not even exist since your knowledge of your brain could be as false as anything else.
Given, then, that we can never be certain of anything concrete about the actual Universe (except that it exists and isn't empty, something exists even if it is only your perceiving mind -- whatever that is) we can forget about "proof" and "certainty" and instead pursue plausibility, or probable knowledge (following in the footsteps of Richard Cox and Edwin Jaynes). In this case the Bayesian estimate for the probability that the Universe would still exist after your brain dies is "nearly certain", on a logarithmic scale (Jaynes proposes the use of decibels to describe the approach to certainty of either truth or falseness of any proposition, since most of what we know is known as "almost certain truth" or "almost certain falsehood", not certain truth of falsehood.
Your total universe almost certainly does not exist only in your brain. The mere fact that you have a referent to something called "your brain" that we all understand is very, very strongly implicative of the existence of an objective external Universe of which your brain is just a tiny, transient part.
Now, don't bogart that joint my friend, pass it over to me...;-)
rgb
Or it my be better put that -- given the infinite number of possible ways reality might really be underneath it all, including string theories, 1+1 dimensional space splitting into 3+1 dimensional space, every religion you can imagine, world of warcraft universe, the Matrix -- it is just fine for physicists and metaphysicists to speculate all they like about this sort of thing and other invisible fairies such as magnetic monopoles, Higgs bosons, dark matter and energy, and gravitons, but humans with a fair dose of common sense will wait for solid evidence to support even the most attractive of these theoretical ideas, and extremely solid evidence to support any of the relatively implausible ideas, such as (pick the religion of your choice, doesn't matter as unless it involves pirates and pasta it is highly implausible).
As far as physicists (theoretical and otherwise) and weed is concerned, it all depends on when they went to school. Physicists in grad school in the late 60's through the early 80's have a fairly high probability of having smoked weed anywhere from once ("without inhaling") up to living with a more or less perpetual nonzero concentration of THC in their blood. I rather think that the probability dropped some in the 80s and 90s, and I don't feel qualified to comment on the 2000s so far. I doubt the relevance of this to the issue at hand, though. There is substantial evidence in the form of several paradigm-shifting revolutions in the way we think about nearly everything since the Enlightenment and Newton that it is a capital mistake to limit your imagination to only the accepted and boring and simple and already consistent with experiment, even as it is an equally great mistake to completely divorce your flights of imagination from empiricism. Physicists quite correctly span the range from complete divorce, a.k.a. "mathematicians" through various flavors of theorist through various flavors of experimentalist right up to empirically grounded engineer. I've been to string theory talks where the theorist spoke about spaces with 8192 dimensional spaces -- with a straight face. It's all good clean fun as long as you don't try to pretend that this should be taken as probable fact unless and until the theory is empirically grounded and shown to have both explanatory and predictive value that isn't easily obtained without it.
rgb
IIRC microwave ovens were "discovered" when soldiers learned that they could put things like hot dogs on sticks and dangle them in front of radar dishes in WW II and cook them in a few seconds. A radar technician who noticed that a chocolate bar in his pocket melted when he was working on an active radar had the bright idea of confining the microwaves and using them to cook food. Hence the early Ratheon "radar range".
So it's not so crazy that someone would learn to reverse engineer (in a sense different from the usual one:-) a microwave oven into a radar unit, or into an information transmission link. The biggest catch, I imagine, is the need for near line of sight (so you'd need to be very high up or very near the border) and a suitable receiver on the other side. Also the fact that moisture attenuates the frequencies used in microwave ovens by design, but I imagine that's less of an issue in Libya.
rgb
You mean like the gpg signing not just kernel but all rpms have had as default for many years now? And while buffer overwrite attacks are certainly not unknown in linux, good programming practices in C plus many eyes on the source code make them way less common, especially in privileged code, in linux. And when they occur, they get patched almost instantly, often within a matter of hours of when they are first announced, and with either yum or apt are often distributed to the entire universe of installed linux systems within 24 hours of the announcement.
It's shooting ducks in a barrel to compare that with the six month lag that Microsoft not infrequently left critical tools like Explorer with wide open bugs in it, unpatched, over the last decade or so. Seriously. Perhaps Microsoft has at long last changed its ways, and is suddenly ubersecure and will be aggressively maintained. To be honest, I hope so, because God knows its been chronically insecure, a bit of a security joke, as long as I can remember, which is back to 1982 and my 64k motherboard IBM PC.
Sure, some of the security problems have come from it being marketed as a "personal" operating system with little permission regulation and splitting of permissions, but sorry, that's a bug not a feature. And most of its problems have come from its enormously slow and cumbersome and delayed history of fixing problems, even really, really serious ones. A cynic would say that they only started to invest money in making this better when they began to actually lose business because of their abominable reputation in the marketplace.
To be honest I hope that they've fixed it so that it is more secure. I have spent many, many utterly wasted days over the last fifteen plus years fixing Windows systems that have become hagridden one way or another, and there are places you can't use anything else because the software you want to run only works on Windows, so you have to apply AV, cross your fingers, and pray, which worked really well except for the finger crossing and praying and there I'd be, trying to salvage data and do a complete reinstall -- again. If you are forced to manage a heterogeneous network with mixed lin and win and whatever, weak links suck and Windows has always been the weak link. I'd be thrilled for that to change -- but it was announced that XP was going to be the "secure Windows" too, and look how that turned out. Better, sure. Secure? Please.
So I'm forced to judge Microsoft on the basis of a mixed personal irritation and laziness and cost index amortized over decades. Cost: high, now and before. Advantageous to the lazy? Not. I spend far longer configuring a new Windows install than I do a linux install, and it is much harder to automate (where in linux it is trivial and doesn't even require much in the way of local media any more). Irritation index? Don't get me started.
rgb
Ah, you mean that they've finally cleaned up their operating system, and if their users get cracked using Windows 7 it's their fault. Sure. I understand. The last 15+ years are now irrelevant. I hereby declare that they never happened.
To be fair, I haven't yet really tried Windows 7 much, because I have all of these leftover XP licenses and XP actually works and runs well on older hardware and under VM software. Windows makes a lovely application on my Linux box for those few times when nothing else will do. But I'm thrilled that the thousand or so of the "world's best programmers" that supposedly work for them finally actually achieved the level of security that Unix in general managed back in the 90's. I'll be sure to tell my kids that if their Windows 7 or Vista systems get cracked that it's their fault, too. That way it won't be my responsibility to clean up the mess.
rgb
Only the idea as described in the article. The questions I'd have for the very different method you describe is how you plan to find a ~1 kg chunk of mass between 1 and 10cm in size and hit it with a laser. That's something like 0.002-0.02 arcseconds, right? Pretty damn good shooting required (NASA or not) and you also have to deal with the spreading of the beam at an oblique traversal of the atmosphere, although I have no immediate sense of the order of magnitude of this. However, 0.02 arcseconds of spreading (while making it more likely to hit) also makes the intensity on a 1 cm target go down by 100 (for a 1 cm beam).
I don't completely disrespect the idea; I think that the idea as described in the article was out of kilter with reality by orders of magnitude, because light pressure is really, really weak. It seems that you would agree with this. Perhaps what you describe might work, although then I'd still suggest that moving the orbit of the threatened satellites with light sails is a more plausible idea -- at least there one can get radiation pressure nearly all day and optimally direct the thrust, and one can be certain that you are hitting the target. How are you going to even know you are hitting the target? A 1 cm ball, even white hot on one side, 0.002 arcseconds across is going to be pretty much invisible...
rgb
Actually yes, repeatedly. I've even published papers on nonlinear optics, although that is as irrelevant as your comment. What specific parts of the results are supposed to surprise me?
Wait, I'll go upstairs and get a laser. There. Yup, fortunately it still works (my sons tend to like to play with them and run down the batteries). Lens, lens, I need a lens. Wait! I know! My reading glasses are an actual lens! Experiment: Shine laser on wall no glasses, a sharp point with the usual spackle. Shine laser on wall through lens -- OMG! How SURPRISING! The dot is spread out. Shine it through at an angle -- ASTOUNDING! The dot is smeared out sideways!
Boy, for a second there you had me worried! I thought that perhaps "laser light" wasn't electromagnetic radiation after all and didn't obey Snell's Law (at least approximately) when it passed through dispersive media! I would have hated to have missed that when I taught graduate E&M courses...
So now that we've established that I have indeed run a laser through a lens -- again -- and that lenses or dispersive media in general do in fact bend even laser light (which is differentiated from the usual hot random source kind only by being moderately coherent but otherwise behaves pretty much like -- light) did you actually have a point somewhere in there, lurking, waiting to be made? As in travelling through a thousand km of atmosphere on an angle through a differential gradient in density won't bend laser light, it only bends the ordinary kind enough for pointlike stars to visibly twinkle on a clear night and thereby limit atmospheric resolution through earthbound telescopes? Or were you wanting to assert that the atmosphere is incapable of deflecting light in general the 0.2 arcsec necessary to miss an order 1 m object at order 1000 km range? Or that the smearing of the beam caused by going through the curved differential gradient obliquely won't cause it to be larger than 1 m in size before it hits the target? Instead of being mysterious, try making a point.
rgb
The light from the sun seems irrelevant, as it's not purposeful, though I imagine they would have to take it into account when calculating when and how (and whether) to aim their lasers.
Interestingly (I did some more looking at this and found some articles via Google about drag forces) the state of the sun is very important to the drag force that eventually does deorbit the satellites. My point was that sunlight at low earth orbit has an intensity of roughly 1.4 KW/m^2, which is comparable to the laser intensity they are talking about, and tends to be ignored even by the people that compute this drag (suggesting that either they -- also NASA people -- are foolishly ignoring an important contribution to the overall deorbiting force mix or that it is several orders of magnitude smaller and hence negligible in the grand scheme of things. Personally, I vote for the latter. Total radiation force is order of total power divided by c in both cases independent of how it is concentrated or not, and over a day the total force exerted by sunlight is likely to have a far greater effect than the total force exerted by a laser in the two hour window that they have some sort of angle -- and I suspect that the drag force itself is greater than either one, probably by orders of magnitude (that's what I was trying to figure out by looking at the articles). But even without the articles, we can do a Fermi estimate. It apparently takes order of decades to de-orbit a satellite from e.g. 500 km due to drag forces alone, with (of course) an. accelerating degradation as it sinks down into the atmosphere. Decades of a small force accumulating to hundreds of km/sec delta-vee for large massive objects, where (say) three decades is basically a gigasecond.
Once again F = ma, and a = \Delta v/\Delta t \approx 10^3/10^9 = 10^-6 m/sec^2. We therefore expect the average drag forces acting on a smallish 100 kg satellite to be around 10^-4 N. Compare to 5x10^3/3x10^8 = 1.67x10^-5 N from the laser, assuming no attenuation etc and it is indeed an order of magnitude smaller (and ditto for the direct force of sunlight), probably several orders of magnitude smaller from 250 km on in given an exponential drop in density and hence drag force with height. Again the drag force acts 24x7, the laser for a couple of hours a day, max, on at most twelve objects a day. On the same 100 kg object, that accumulates \Delta v at order of 10^-3 m/sec/day (multiply by 10^4 seconds in two hours, divide by 10^2 kg). A millimeter per second per day. Doing a viral estimate of the change in orbital radius, that should result in a change of around a meter in orbital radius per day, a result not incommensurate with the 10+ meters per day Fermi suggests that orbits change, on average, due to drag forces (assuming decadal decay times). A meter plus per day makes the scheme borderline plausible.
As for ideas any freshman could shoot down -- you have heard of SDI, right? And religion? Scientists are perfectly capable of proposing things and the government is perfectly capable of spending large sums of money on the proposals even when simple computations suggest that they are implausible, and humans in general are capable of believing almost anything that "sounds good" to them. If I were a reviewer of the proposal, I'd want to see the actual computations that show that they can a) detect a piece of space junk on a collision course with a LEO asset; there's so much out there that they have to use statistical mechanics to estimate the probability of collision at this point, and not all of it is of human origin; it comes in a wide range of sizes, reflectivities, and material compositions. b) identify its orbit precisely -- and I do mean precisely, to within centimeters, while it is being slowed by drag (possibly as it tumbles), sped up and slowed down by the solar wind and solar radiation force (again in an unpredictable and even chaotic way), and even is bounced around by geomagnetic effects (especially if it is a conductor) a
Sure, but what's surprising about that? Peter Norton was more than a bit of a tool back when he wrote bad columns in PC Magazine and sold "Norton Utilities" on the side. I'm sure the software is no longer being written by Norton, but it has questionable roots.
One question I've never been able to answer to my own satisfaction: Why does Microsoft allow antivirus companies to live? This is so antithetical to their own standard business practice -- if somebody makes money on it, and it is software, clone it and take over the market. Yet they don't either clean up their operating system's act by actually making it semi-secure or make their own antivirus software, something that really does seem as though it should happen at the deep OS level. Yet antivirus and antispyware companies flourish. I don't get it.
rgb
No, they got caught. Repeatedly. For example, on the browser issue. They've been in court in a massive antitrust case that in a just world would have resulted in them being broken up. One can go down a list of their major, massive, ethical violations and questionable business practices (all of which have been massively successful in killing off its competition). Take Borland, for example -- the actual inventor of the IDE (good old Turbo Pascal, $45, on the IBM PC). Take Lotus. Take Wordstar and Word Perfect. Take the vast range of young entrepreneurs who created massive markets and amazing new products in the early days of the PC, only to be systematically subsumed and driven out of business as the company that made the operating system co-opted their ideas, cloned their products, changed the operating system and/or compiler so that their products broke (while the Microsoft versions, developed after all by the same people who were changing the OS, didn't) and then using absolutely classic FUD techniques to win over first 1/2, then 2/3 and eventually all of the market. Take OS/2 (oh, wait, you can't, because of Microsoft's "ethical" behavior). Take their unit pricing that more or less forces all vendors of PCs to offer only Microsoft as the default preinstalled OS choice if they plan to sell any PCs with Microsoft operating systems preinstalled, in a marketplace that is so price competitive that the price differential is near certain death (which means that you pay the "Microsoft tax" even on a computer you buy to install linux on).
/.'ers. I can even remember a brief period back in the early to mid-80's where it actually was fairly ethical -- Microsoft was once upon a time the good guys, the provider of an admittedly mediocre but nevertheless adequate operating system on a marvellous "new" invention, the IBM PC, the machine that let individual humans get their own computer and fight against the massive power and enormously exploitative pricing of the giant big-iron computer manufacturers, the machine and OS that unleashed a flood of entrepreneurial activity as anybody could program new software for it (and thousands of people did) and hope to make a fortune (and thousands of people did).
Why put up links to articles on MS's unethical behavior? I've lived through it. So have lots of
Then they got greedy. Why should all of those other people make fortunes using our OS and compilers, they thought? We have all of this money, and all of these programmers, and this marketing channel. All we have to do is wait for people to have really good ideas, and then steal them! Integrated tools? Wow, good idea! Let's steal it! Spreadsheet? We can write one of those, too! Word processor? Piece of cake! Games? Too much trouble -- we're making too much money as it is, let's just start buying up companies, or parts of companies.
The upsurge of the Internet took them by surprise, of course. TCP? IP? Open standards? HTTP?
Ever since they have been trying to somehow lock it down with proprietary and/or patented technology in some "killer app" way that would make all of its pesky competitors roll over and die, but not quite die, if you know what I mean. They got a big scare when Apple nearly went belly-up -- if it had died the rest of the way they might well have been broken up in the antitrust suit, but fortunately all of the big companies had pension funds that were heavily invested in Microsoft stock, and so nobody really wanted them to lose. It suits them to have "competition", enough for show.
Linux is, and has been for some time now, a dilemma for them. In their world, things like Linux shouldn't be able to exist. No matter how cost-effective and efficient Microsoft's product development and support is, it can't compete with free. It also made a living for fifteen years by hiring the best and the brightest programmers in the world, until its practices became s
a) The article methodoology explicitly claims to be using light pressure only.
b) If they can actually hold a 5 KW laser on target at a single point on the object it might heat it up to where ablation occurs, and yes that would produce easy orders of magnitude greater (if still tiny) thrust. However, I don't think they can come close to achieving this and they'd have to work quite hard to convince me before I was willing to drop $50-100 million dollars on the experiment. Atmospheric ripple and other sources of vibration would -- IMO -- make that dot bounce around all over the place while conductivity spreads the heating out. I'm not completely convinced they can hold it steady "on" an orbiting object at all, although this is where they would indeed be spending fifty million or more dollars for every million they spent on the actual laser. How would they even know if they are hitting it?
In star wars type lasers, they (I'm pretty sure) shoot very brief, very high power PULSES to deliver a significant amount of heat in the very small time the laser will hit "somewhere" on the target. That might work here as well, but that isn't what the article is advocating.
In the after-article article they make it clear that they're not trying to destroy the objects (which they cannot do in any event), and that they recognize that it would take decades to actually knock something out of orbit (a vast underestimate -- try centuries). They allege -- and I'm still having a hard time seeing it but it is barely possible -- that they can divert the orbit of something enough to prevent a collision. The after article also makes it clear that the actual cost of building a laser system to do any of this is orders of magnitude more than a million dollars -- that's the cost of just the laser, not the targeting system, which has to be just as accurate and stable as any star wars antimissile laser device. They also clearly state that they are relying on light pressure, not outgassing or heating in general.
Changing an orbit enough to cause the junk to miss by meters instead of hit something is at least in the realm of the possible, given that tiny changes in orbital velocity can make large changes in orbital position over a long enough time base. Large at least compared to the size of a space ship.
I'd like to see the actual arithmetic that they use to justify this, though. The piconewtons from the laser actually have to be compared to things like the piconewtons being exerted by the light pressure from Mr. Sun at this sort of scale, and the sun shines on them all of the time. The forces are likely within an order of magnitude of each other, and are comparable to the extra force you experience when you lie down on the beach at noon on a sunny day.
rgb
I commented elsewhere on the actual numbers, which show quite clearly that even a 5 kw laser would exert at most completely irrelevant forces on any object large enough to actually see from earth and hence target -- accelerations on a good day of 10s of microns per second per year of radiation pressure. Having RTFA and noted all of the corrections by the authors (of the idea, if I understand things correctly) it is still an enormously stupid idea. What part of piconewton scale forces is difficult to understand?
I give this one as an assignment for my intro physics classes -- suppose you have a megawatt laser with a beam 1 cm^2 across and mount it on the rear of your spaceship to use as a drive. Wow, a whole million watts of power! Surely that will provide the ship with all kinds of thrust!
Sure, if all kinds of thrust is a few micronewtons.
You'd get more thrust -- and probably more net delta-vee for any acceleration time you are willing to wait -- if you simply took the laser to the door of your capsule and threw it, as hard as you can, away.
rgb
What? You insist on doing arithmetic? Something like P = I/c (within a factor of 2) for the radiation pressure exerted by light? So that if we make a very generous assumption of a kilowatt in a single square centimeter, we have 10^3/3x10^8 \approx 3 x 10^-6 Pa. We multiply by 10^-4 square meters (one square centimeter) and get 3 x 10^-10 Newtons. Take into account attenuation in the atmosphere and the fact that the beam is wiggling all over the place because of atmospheric thermal ripple and lensing, and you would be lucky to exert 10^-11 Newtons per kilowatt per square centimeter of laser beam.
If our supposed space junk is travelling in an actual low orbit, it is travelling at roughly 7 km/sec. Let's assume that it has a mere 10 kg of mass -- if it is much smaller just finding it from Earth will be difficult, let alone hitting it. Lessee, F=ma, so we can give it a maximum relative acceleration of a whopping 10^-12 m/sec^2! A year, on the other hand, has a mere \pi x 10^7 seconds, and of course we can shine our laser on the object at most a few hours a day -- again, a duty cycle of 10^7 seconds/year would be enormously generous.
This means that we can -- over a whole year -- change the velocity of the junk by 10^-5 meters/second! That's right folks, you heard it here first -- ten microns per second per year of thrust with a 1 KW laser beam 1 cm across, and downhill from there in nearly every direction.
Of course this is still wildly optimistic. The problem is that we are exerting the thrust on the object from underneath. This is more or less at right angles to the direction of motion, and hence does very little to speed it up or slow it down. In fact, pretty much nothing. If we wait until it is directly overhead to hit it, we get the cosine of a nearly right angle as a transverse component and can only fire on half of the overhead pass before we are hitting it from the rear and speeding it up again. If we fire at an oblique angle, to get a good dot product cosine with the direction of thrust and direction of motion, we have to go through an equally oblique layer of atmosphere that both bends the laser beam (making it effectively impossible to hit the target) and attenuates the kilowatt still further (reducing efficiency at about the same rate the dot product improves).
If the material were highly ablative, and if we could hold the beam steady enough to actually heat the object to where it boils, we could get some real thrust. Even a thin layer of actual reaction mass being boiled off of the surface would exert orders of magnitude more force than a perfectly reflected laser beam. But even orders of magnitude more thrust would almost certainly not suffice to slow the object enough to in any possible drug-addled, hallucinatory Universe make this an economically feasible, intelligent idea.
Now I know who was using the cocaine found at NASA today. Whoever it was that dreamed this one up.
rgb
You don't think that their monster rescue effort is to try to save Godzilla, do you? Could he -- even he -- have been injured in the 8.9 earthquake? Could Mothra have hit him with paralyzing sound waves as he surfaced?
Although it would be a good, clean solution to the meltdown problem, wouldn't it..;-)
rgb
Indeed. In fact, this is clearly the same plant that he once ate the core of in order to activate his glowing back scales and enable him to blast his foes with radioactive fire breath. I'm guessing that they just didn't repair the cooling system very well -- but then, it was in pretty bad shape after he ripped it apart.
In fact, the quake itself was probably Godzilla breaking free from his watery tomb. Look out Tokyo!
rgb
Wow, really well said! And typical of the "science" of the debate. Why not just make a religion out of it and be done with it? rgb
Right, so in this particular zero-sum game, the only way to be certain not to lose is to use a true-random (or as close as makes no difference) generator to select your moves, e.g. roll a die, 1 or 6 is rock, 2 or 5 is paper, 3 or 4 is scissors (first order correction for the weight of the pip cutouts). No matter what your opponent's strategy, this leads to a draw in the long run.
To win, you have to observe your opponent's sequence for correlations and exploit any patterns you discover. Indeed, I've often thought about writing a NN to play the game on the latter basis, perhaps fuelled by a library of typical human correlation matrices. However, if the game is played mathematically, the player that uses any proactive strategy loses. Strategy basically means "nonrandom move patterns", and any systematic deviation from randomness can be detected against a background or null-hypothesis random play (in time) and exploited, any algorithms used to exploit apparently nonrandom play can be detected and exploited.
rgb
Great video, good argument. I've seen the argument before, of course, and find the lipid-bilayer bit to be moderately convincing. However, it is only one of a moderately long string of proposed models or partial models, obviously in the "replication first" rather than the "metabolism first" camp. Wikipedia (as always) has a list of at least the primary (named) propositions. In particular the sea-foam (bubble) argument is almost identical to this one, with an even more generic source of compartmentalization and different sources of free energy.
The only real problems that I have with this or the other models are:
* There are still a lot of models! There is still not good agreement on even basic chicken/egg things like metabolism/replication. The reason there are a lot of models is that there is not a lot of compelling evidence favoring one model over the rest. As a physicist/outsider, I find the replication first argument slightly more convincing because I write genetic optimization code and am aware of the enormous power of a good GA, but there's a whole lot of chemistry that is not, actually, reducible to nifty dots in a movie that say "this is what happened" -- not without evidence or actual numbers and experiments to support it.
* The good thing about the video is it shows a plausible chain (relying heavily on the aforementioned power of a GA to "discover" favorable proteins which are then first weakly conserved, then more strongly conserved as some of the proteins discovered improve conservation) from stuff to primitive cells (with metabolism one of the discoveries along the way to eventually free cells from their volcanic vent). The bad thing is that there are a whole lot of probabilities in there that the video implicitly asserts are essentially unity over specific ranges of time, without anything vaguely resembling proof! Or even a mathematical argument. It basically proposes that if you set up a heat source in a soup with roughly the right local chemistry and wait some unspecified time, the soup will have a macroscopically relevant probability of spitting out a living cell with both metabolism and replication capable of living away from the heat source. The problem here is obvious -- that is a serious claim in statistical mechanics and chemistry, where big numbers/small numbers abound that can easily be so big/so small. A sound computation of the probabilities might end up with many lifetimes of the visible Universe per (e)vent, so that only by having a visible Universe filled with vents does one get a finite (but very small) number of "wins". Or, as you seem to wish to believe, it could happen with near certainty around any vent given a mere million years of cooking, so that life is essentially certain on any planet with vents and the right chemistry and temperature and pressure ranges available "somewhere" for geological times. The same objection holds for the other models -- they show some greater or lesser degree of plausibility without having anything like a computation of the actual probabilities beyond hand waving.
My argument is still largely unchanged, as it is model independent. If life is so likely as to be nearly inevitable, then life abounds in the galaxy and has for some ten billion years. It is not then implausible that life has evolved to take advantage of unique niche environments such as comets, moons, gas giants; it is not unlikely that life seeds the stardust leftovers from the destruction of life-bearing solar systems upon the death of their sun. The rarer abiogenesis is, the more likely it is that the life we observe is the result of nucleation elsewhere followed by transport rather than local nucleation. For a wide range of probabilities assigned to the event itself, we would most likely be descended from interstellar hitchhikers from genetic stock that might be ten billion years old, and even in the case of high local probability there would be something of a race between the evolution of
I think that the argument would go something like this: The Universe is 13.73 billion years in its current post-bang Yuga. Life can arise on any planet formed out of supernova remnants of a second or third generation star. There have been planets so formed for at least 10 billion years, probably longer (since at least some large, short lifetime metal rich stars would have been formed after the first very short lifetime supergiants went nova). Current estimates for the numbers of third or fourth generation stars with planets with the building blocks required for the formation of life are in the hundreds of millions to billions, over most of the last 10 billion years. If life arose on any planet in the Milky Way Galaxy some 9 or 10 billion years ago then natural processes from supernova to solar wind could easily have seeded the interstellar gas clouds with spores, spores that accrete along with everything else into the masses of matter that eventually collapse into a new star. Any of these life-bearing packages that happens to fall into a suitable environment on a newly formed planet can short-circuit the abiogenesis route for all or most planets formed in the Milky Way after the first few managed the trick.
The reason this is plausible is simple. If abiogenesis is indeed likely, then it is likely that it happened long ago and that traces of life can be found throughout the Oort cloud and beyond, because there are literally billions of years for it to cross the interstellar distances at the speeds of outgoing shock waves from supernovas and outgoing solar wind. In that case it might be a race, but fully formed organisms preserved in comets and other leftovers of leftovers of exploding star systems would have a huge advantage over local organisms that appeared from abiogenesis, which would be extremely primitive (and hence vulnerable) for a time.
If abiogenesis is in fact unlikely -- and of course we have no explicit model for abiogenesis that is yet accepted as being particularly plausible or probable in the sense that it is well supported by either evidence or even good seat of the pants statistical models or computations, so it might well be rather unlikely -- then even if it is unlikely that life arose on Earth (say, one in a million) the Galaxy as a whole has probably had tens to hundreds of millions of shots and life has arisen tens to hundreds of times, and every life-bearing planet very likely sheds "life" into its galactic vicinity at some nontrivial rate, especially in catastrophes such as when it is struck by an asteroid or blown away.
I therefore think that the meteor evidence is highly intriguing. To be truthful, I'd think it very odd if meteors and comets and dust particles from the Oort cloud on out did not have evidence of life -- that would suggest that life is somehow unique to Earth, which is most improbable. A chain reaction spread of life from one or more nucleation points that spontaneously appeared in a very large sample space indeed seems at least as plausible in the worst case, and far more plausible overall, given a state of near complete ignorance about the abiogenesis process itself.
Of course this could change -- somebody could come up with an evidence-supported model for abiogenesis, or a computationally plausible mechanism, or demonstrate it in the lab (at which point we could compute the probabilities a bit better). Or we could start to find evidence of life in all sorts of rocks that have never been anywhere near the Earth, once we manage to get out there and visit them. Or a big meteor shower could give off green light that blinds everybody who watches it and the next few days these big tree-people with sharp spiky things could sprout up and start eating people. Evidence, in other words, should be our guide here, not a personal bias towards local abiogenesis versus abiogenesis long ago and far away. Life is probably around ten or even eleven or twelve billion years old in the visible Un
Where are my mod points? I squandered them all, squandered them all. But this is very funny.
A more interesting question is what will happen if they don't prove supersymmetry and fail (once again) to find the Higgs Boson, and in fact find "nothing particularly interesting" (perhaps beyond insight into the quark-gluon plasma, which is already forthcoming) all the way out to its maximum energy across all experiments.
Lack of evidence is not evidence of lack, but it is worrisome. It leaves open the possibility that we are off on completely the wrong foot, that reality is really nothing like our models, and we might have to go looking for new physics to consistently explain things like particle mass and gravitation and cosmological deviations from gravitation currently wrapped up in the "dark matter/energy" hypotheses.
Come to think of it, we might learn just as much from failure as from success. As usual. Even if it is a very expensive failure, compared to the knowledge gleaned from it.
rgb
Your curve clearly ends with an artifact in both quantities plotted caused by the fact that it is averaging zeros from beyond the end. You can't smooth right up to the present!
Look at the actual data! The sun has just come off of a stretch of four out of five cycles that are basically the among the most active on record or inferred by proxy in the Holocene. There is a clear dip/levelling in temperature in direct correspondence with the relatively low cycle across the 60s. The last solar cycle was not significantly lower at peak than the two immediately before it, certainly not enough to conclude that we should have cooled without knowing and quantitatively understanding the mechanism by which the earth cools during periods of low solar activity, which is, of course, when actual solar irradiance peaks! In other words, when the sun has no sunspots, it is actually slightly brighter and one would expect (if anything) warming, although the fluctuations in brightness are a trivial fraction of a Watt/m^2. This is why the primary climate models ignore solar variation as an important driver -- they cannot see how it works.
The other thing that you persist in wanting to do is look at the decadal scale changes as significant. I repeat -- until you can predict accurately how the Earth's "equilibrium temperature" (the temperature it is being driven to by the ongoing mean balance between sun coming in and heat going out) in an enormous system that takes in heat here, caches it there, circulates it from here to there, and does all of this in an environment where how effectively it gains or loses head depends on circulation patterns that appear and disappear on a multi-decadal timescale you have no idea what temperature it "should" be with or without CO_2.
However, you can easily rectify the situation. Extend the base of the very plot you built to 10000 BCE, along with CO_2 (which does indeed vary synchronously with solar state and temperature, with a decadal lag -- as the oceans warm they give up massive amounts of CO_2 as the complex thermal equilibrium concentration shifts). Then just mentally try to a) argue for high sensitivity -- global temperature takes decades -- multiple solar cycles -- to reach equilibrium. We were probably still in a warming phase in the last solar cycle in the sense that the "true equilibrium" temperature was warmer than the actual temperature, given the state of the sun. Also bear in mind that in any eleven year cycle local events in the chaotic cycle can confound any simple prediction. Isn't that at the heart of the CO_2 argument, after all, given that it is a terrible proxy for temperature over any multiple century range selected at random out of the last thousand years? For a single example, last year we had a vast bolus of methane -- and I do mean vast, cubic kilometers -- methane made up about 40 percent of the leaking crude by mass -- released into the atmosphere. Methane is a greenhouse gas over 20x as powerful as CO_2 at trapping heat, and it has a long half-life in the atmosphere. Methane from the Gulf spill no doubt blanketed a significant fraction of the Earth's surface in the vicinity of the spill as it was carried by the prevailing winds, producing the same sort of local warming that affects our cities and airports (with CO_2 producing planes constantly taking off and landing, often right above the primary weather stations that are so conveniently located there). Did this confound the lowering temperatures one might have expected given the volcano and slow/low solar cycle? Who knows? What matters isn't any single year in any event for this very reason.
But we'll see, very soon. The sun is rising what will probably be the lowest peak in over a century. The Earth has plenty of heat stored up from the heating phase, and of course there will be a lag and significant fluctuations as its chaotic head delivery system self-reorganizes, but by the end of this
As long as "a moment" is considered to be (say) 25 to 50 years and doesn't involve the creation of an easily exploitable global carbon trading system that would be corrupted into something far worse than the oil multinationals (and would probably somehow end up being controlled by them), I'm fine with that. There are plenty of very good reasons to build renewable energy resources and energy resources that don't involve burning a limited and valuable resource; if we'd spent the $500 billion or so that Iraq has ultimately cost us on massive solar even at a loss we would be more or less energy indepedent already, and because investment on that sort of infrastructure has a stimulating effect on local economy and prosperity, we would have actually made several trillion dollars in ROI instead of losing a trillion and a half or so in an economic collapse. If Obama could stop sitting on his hands and say "screw AGW, its an unproven hypothesis and we're not going to participate in carbon regulation and all that, but we are going to begin the next great science and technology project with the same dedication and investment of resource that we used to develop nuclear weapons and put man on the moon -- let's budget $50 billion dollars (or more) a year into direct subsidy of the construction of GW scale renewable power" then in ten years or less nobody would care about oil or carbon.
We could then use our new resources to stay moderately warm in the coming Maunder Minimum, and maybe forestall the gigadeath that will likely ensue if early frost starts coming regularly to the great granaries of Russia, China, Canada and the US. Which could happen extremely quickly of we enter a true grand solar minimum over the next two cycles. Warm is good, actually. We like warm. Warm permits crops to be grown, people to be fed, energy to be conserved, while we work on dropping the world's population without war, disease or genocide. Cold, on the other hand, would be a disaster beyond your imagining, and cold (if it comes) will strike quickly -- on the timescale of a decade or two, not over 100 years. Fear the cold.
This is part of the sheer evil of the IPCC's politicized abuse of the scientific process. We should be looking at all the hypotheses, even ones that are diametrically opposite to what we think is most likely to happen, as long as our knowledge of the science is uncertain. If we get cold after preparing for "certain" warmth, this will no longer look like a game.
rgb