In a SCRAMjet, we are not accelerating and squashing the air like the Olympus engines on Concorde, but trying to get the thrust from the air as it goes through. I had skipped this bit to keep my note short and accessible to people who might be confused by the original article. Rather lazy writing style, and serves me right for being caught out.
The chess ranking is typically a 3-digit figure. Given two chess players, you can work out approximate odds of one winning from the difference in these figures. The figures are compiled from the games people have won, and the ranks of people they have played against. As in multi-choice tests, each individual question or game has a wright (win) and a wrong (lose) solution, and a stalemate (not filling in anything) option. From this we can estimate ranks of people we have not met; we can estimate ranks of people in history; we can even estimate corrections for ranks between cultures. For instance in the 19th century, how might a woman chess player in London (where the culture did not encourage chess) rank against a man from Prague (where cafes typically had chess boards in the tabletop, and most people played with friends and strangers in their lunch hours) had their backgrounds been equal, and assuming a native talent for chess is spread equally? This last point is not obvious - the differences between London and Prague and between women and men may not be wholly cultural, but the others can discuss that ad et ultra nauseam.
No-one designed chess with a perfect solution, and yet we can rank people. The IQ tests started from a similar point. People did not understand what intelligence was, exactly, but if they made tests that seemed to be testing the right sort of thing, and got the best people to design the next round of tests, then it was hoped that an incisive test for intelligence would evolve, even though no-one had defined what intelligence was. Unfortunately, in the early days, what was being tested as 'intelligence' was probably better named "how like minded are you to the white male that designed the test". The test can be as exacting as a chess ranking if you do enough tests, but the figure is less useful because it is not a measurement of something abstract and useful (unless you were IBM in the sixties, looking for white males with short hair that would sing the company song, in which case it was perfect).
There is a further downside to IQ tests. If you sit and stare at them, you can often reason a second or third possible answer using different readoning. I also have a problem with forms that means I think long and hard about the answer, and then tick the wrong box. The trick seems to be to work really quickly, and let your instincts drive your answer. I have only ever done about three IQ tests, and all of these were done ages ago for job applications to computer companies. The last one must have been twenty five years ago. We had two hours and 300 questions. I deliberately hammered through the questions, and handed the paper in after 40 minutes to avoid the temptation of fiddling with the answers. Incredibly, this seemed to cure my usual error rate with forms, and I got a perfect score. I wasn't any smarter that day - I just happened to be in the zone, I guess.
Didn't get the job, though. They thought I was too scary.
Thinking about the original post, though. The guy claimed that a multi-choice was 'fraudulent'. Isn't 'fraud' where someone is trying to deceive someone else? Multi-choice questions are an attempt to separate the test for the presence or absence of knowledge from the talents of presentation (good handwriting, confident presentation style, etc), but often flawed by laziness in trying to pass off examination skills to a computer. A good multi-choice questionnaire would have to be much longer than such tests usually are to reliably separate the thing you are trying to measure from the noise (think how much mesurement goes into a chess ranking, for example). But 'fraudulent'? And this was supposed to be a legal exam? I have my doubts about the original posting. Interesting subject, though.
Scramjets look good on paper. The thin air coming in is compressed by a series of standing shock waves. Unfortunately, the geometry of these shock waves can easily be upset by small distortions in the engine, which in turn can lead to changes in the stresses with in the engine, which - to cut a long story short - can mean the engine spectacularly demolishes itself when faced with real bits of atmosphere with unpredictable air currents. I found the flight time in...
It may not sound like much, but six seconds is very respectable for a scramjet. Yay!
There is a lot of touting about how this would get you from London to Sydney in 40 minutes and stuff. I am not sure how true or economical this is, even if scramjets can be made safe. When you are flying fast, you can either take your oxidant with you (as rockets do) or you can scoop it up as you go along. Scooping it up as you go along means taking in air that was initially at rest and getting to move at the speed the engine is currently going. As only 20% of the air is actually the oxygen you want, this is not necessarily an effective thing to do. It becomes most effective when the oxidant (oxygen) is a lot heavier than the reductant (fuel - and hydrogen is particularly light), so scooping it up as you go takes a lot off the take-off weight.
The other London to Sydney option is to get just beyond the atmosphere using a conventional rocket, then going ballistic and weightless for the main distance, and re-entering and gliding, a lot like the space shuttle. While being weightless is fun, being weightless for 20 minutes makes most people puke, so a large passenger jet might skip the atmosphere and retain a little gravity. A scramjet might be used for this.
We were at a bus stop. Someone across the road came out of a blcok of flats, and tried putting a key into a car. The alarm went off, ewven though the key had unlocked the door. The person opened the bonnet, and pulled, and hit, and eventually blessed silence returned. He then managed to drive off. He could have been stealing the car. We did not think so, but he might have been. If you see a car alarm going off, do you rush to the defence of someone else's property? Naah. Even policemen who stopped when they saw me struggling with a car door and an alarm in a car park moved on when I gave them a wave and a I-can't-help-it shrug.
I have a Jeep Cherokee (right hand drive). This had an alarm which went off even though the door could be opened, which means the bonnet could be opened, and the alarm could be disconnected. If the side window is left a crack open, the alarm can go off when a gust of wind hits it just so. It then stays on until it is smashed by infuriated neighbours (this is what did for it eventually) or the battery is flat, whereupon the doors all unlock. The car is dead, so I ring home for a jump start. We connect up the batteries, whereupon the doors lock again, locking the keys inside, and the alarm sounds until the battery is flat again, or I rip the wires off. Stupid, stupid, stupid!!!
I believe BMW have an even finer version of the phone battery alarm trick. If you leave the car in the garage, the alarm system is still on. After about two weeks the battery voltage may dip beneath 11v. The alarm system reckons that someone may be trying to run down the battery, so it flashes the lights, sounds the horn, and uses up the rest of the battery in in the garage. Then it unlocks all the doors. Hooray.
Just back from Tinsel Town after talking to some of the dudes in the article. Still jetlagged, so it feels a bit unreal reading about it in Slashdot. Still, I'll do my best to explain why things are the way they are...
A film is not often made by a single body. If you are shooting to film, then this will get handled by an editorial department. You may have a fast telecine scan for reviewing the material as dailies. Some of these scans may be used as low-resolution proxies for initial grades. Some chosen bits of film may get re-scanned on a slower pin-resolution scanner for inclusion in the final film. Artificial rendered scenes and special effects may be done by specialist houses, then composited in a post-production house. Your film may have 25 4K images per second in the final version, but the data used to generate it is scattered over the place - if you think a good IT department should be backing all this up, then you haven't worked on a film, my friend. As deadlines approach, people may be working stupid hours, and filling up all the available storage. Then the film gets released, and either makes a billion dollars or doesn't. Either way, the tension is off, people take holiday and zonk out. Nobody will be picking over the cutting-room floor or its digital equivalent looking for things that might be useful twenty years from now. By the time people are back from holiday, they don't know or don't care.
Your end product may be big reels of negative film that you send to a film lab to make prints for cinemas. The lab should keep the golden master clean, and make most of the prints from a second copy. This would be a sensible time to make an archival print of the film. The lab can transfer the whole thing to black and white film. Black and white film does not fade, like conventional colour film does, even in the can. You are getting the print lab to do a pretty full backup of the released film when your people have all gone on holiday. These days you need to back up other stuff. The soundtrack is digital. You will have extra data for the releases in different formats (5:4 TV, 16:9 widescreen, IMAX, etcetera). Still, it is a lot better than nothing. But it is not often done.
The other think is to know what to archive. Very little of the newsreel film I had to sit though as a child to get to the cartoon has survived. Key stuff like the Queen's Coronation or the outbreak of WW2 was clearly history, and put on a special shelf, but little of the day to day stuff survives. There is one cache that survived when a cinema closed, and the tins of newsreel went into landfill. The cinema was in Alaska; the landfill was permafrost, and the film was kept in near ideal refrigetrated conditions. Apart from this fluke, it has probably all gone.
There will probably be digital solutions in time. Increasingly, as we have to manage more different sorts of digital data, there is a need to organize and track everything, which ought to mean it is possible to archive all the essential bits that go into any production. Many other people have posted on the problems of knowing what is on (say) a FAT16 Windows 3.1 disk in some 1980's image format. You can keep copying the data to overcome the degradation of the physical medium, but you still have to know what it means. I know of a system for archiving film images, where the people who did the archiving left the company, and one of them took the laptop with them that had the archiving software, so the ability to read the archives went with them. Do you archive the archiving system? Then, do you archive the system that archived that? Yes - basically, that is exactly what people are proposing to do. But it takes a bit of organizing, and we are not there yet.
Film, on the other hand, has visible images. The 35mm format has remained readable for over 100 years. Even where nitrate stock has flowed over time, we still know what shape it ought to have been. Sometimes we can get something back if we want it badly enough.
Light can usually go along a path in either direction. If light isn't getting from you to the outside world. If the 'invisibility cloak' is a type of Luneborg lens with phonotonics materials to get the high refractive incides needed to get light to avoid the bit in the middle - the sort of thing in this month's 'Scientific American' - then yo will seem to be at the centre of a shiny ball. Kinda interesting to know how you would decide when all the bad guys had gone away, and it was save to take a peek out.
I read through the original article. Then through the links. Then some of the posts. Oh dear, oh dear. Most upsetting.
We should not believe all we read in the web. We should not believe all we read in books either. Some stuff is accurate, some is mistaken, some is made up. Unless it is all chaos, and will always be chaos, we believe that in time the errors should be found and be corrected. Sometimes people come across a large chunk of fakery. The discrediting of the work of Dr. V.J. Gupta cast doubt on much of the geolegy of the Himalayas for the last 20 years ( see http://www.scientificvalues.org/newsnovember2002.h tml ). Nevertheless, we sift through the rubble, and find out what can be kept, and what can't. Or we sit in the chaos.
Wikipaedia relies on voluntary contributions. Take a cross-section of the internet who will do somethig for nothing, and you will always get a generous helping of dross - spammers, trolls, phishers, fundamentalists, vandals, and general nutbars - with, maybe, a tiny fraction of people who have understood a subject, and simply want to share that understanding with others. I admire the spirit that believes that this tiny fraction may prevail. The fact that someone with suspect credentials is found out, and their work is given a second look, shows that the thing is working. You see this when newspapers have to print a retraction, or TV programs broadcast a correction. If you didn't see this, then you should worry.
It seems there are a lot of people out there with heart and spleen problems. Good lord, but there is some serious vitriol there. Who are all these people without fault, jostling to get their stone in first? What makes them think Jimbo Wales owes them a personal apology? Who elected you lot the Guardians of Truth, eh? Sheesh...
So, my grateful thanks, Jimbo and all Wikipaedians, for a most useful and valuable webpage.
Okay - I have probably earned myself a good flaming in Internet Hell for that heresy. Might as well do a proper sheep-for-a-lamb job. This next bit goes out to EssJay...
Hi, EssJay. I am not in your field, so I can't read what you wrote, but your friends seem to like you and speak well of you. Cheer up. You don't need a doctorate. I have got one, and it's not a lot of use. Dr. V.J. Gupta had a doctorate. If your contributions are good - and I do hope they are - then pick another name, and come back a bit later when the legions of shit-throwing monkeys have found something else to amuse them. Do no harm, do a bit of good when you can, and we'll all get there in the end.
Figures taken out of context do not really help. The atmosphere is complex. Dump stuff in one part of it, and it does not necessarily turn up in another place. We know things like the explosion of Mt Tambora (http://en.wikipedia.org/wiki/Year_Without_a_Summe r) caused a dramatic climate change. It is possible that volcanoes like Mt Erebus has a significant effect in a much quieter way because it is high (over 3700m), near the South Pole (77 degrees south), and so it can output halogens and halogen compunds which do much more harm than carbon diodide for the ozone layer.
If you assess risk by mass, then you can blame global warming on cows. Methane reduces ozone. Cows fart out lots of methane and other stuff. By mass, they produce much more than all aircraft. This is probably wrong, but widely quoted. But aircraft chuck their stuff out in the upper atmosphere, where it gets further and probably has a lot more effect.
We cannot do the traditional experiment - have two worlds, one with a population and one without, and measure the differences. However, we can look at the natural experiments in the solar system. If the icecaps of Mars have shrunk at the same times as the icecaps of Earth, then there may be a link. If we think there is a link, then we try and gather more evidence. This is what science does. It's a bit dull, and it rarely moves as fast as we like on important issues. It may be more fun to report on academic rows, controversies, and consparacies. But they really don't help much in the long run.
When an organism mutated, I wondered whether the old version might be stuck under CVS somewhere in the genome. Think of how many generations of mice you must have between each ice age. Suddenly, you are the first mouse in 20 000 generations that has to deal with an ice age. If your current survival strategy is not working, under stress you might revert to an earlier version. After all, earlier versions had worked once, and might be better then trying mutations at random.
Unfortunately, junk DNA is not a place for information. Unlike most 'junk' things, junk DNA is often very clean repeated patterns that cannot contain much information. In general, smaller cells have less junk DNA, suggesting that it may have some structural purpose. The amino acid set is a nice molecular lego for bulding all sorts of shapes, as well as storing information. There may be a repository, but it isn't in junk DNA.
You used to be able to get desktop scanning electron microscopes. These were not popular at the time (1970's) - you wanted a big vacuum pump or you waited ages before you could look at anything, and the electronics usually meant that the thing was pretty huge. The resolution was nothing like the big SEMS, but it was still better than anything optical, and the depth of field was might greater.
If you replace the diffusion vacuum pump and rotary backing pump with a modern turbomolecular pump, then you don't have the warm-up time or the noise. If you have a small aperture, and pump the thing hard enough, then a 25KeV beam will travel a few mm in air. Use a magnetic field to turn the beam just before the aperture and the air going through the aperture won't roar straight up the electron optics. People have viewed living cells under electron microscopes so having a high vacuum electron optics with a small open end is possible. A bit of air can also avoid the charging problems, which is whjy SEM specimens are usually coated in gold first.
If you can sweep an electron beam over the surface you can get the SEM view of it, but you can also use the electron beam to evaporate and ionize material, which can then go into a mass spectrometer. You can look for X-rays, electron diffraction, and so forth. There's lots of stuff you can stick onto a SEM that could probably be minaturized down to the cassette player size of the Tricorder.
It's not 'life form readings at 500 meters' but it's a start.
A conventional rocket motor chucks out lots of hot, ionized gas. In the lower atmosphere, this comes out as a long, thin flame. As the atmosphere gets thinner, the gas can fly out sideways. You have the paraboloidal bells at the base of the rocket with try an convert this sideways motion of the plasma into downward motion, so you get as much forward momentum as you can. However, the gas in the bells is colliding with itself as much as with the engine walls, so you will still get stuff spraying out sideways. What you would need is an impracticably huge bell shape so the gases thin out to the Knudsden regime before bounding specularly off the walls. However, you could steer the heavy positive ions backwards with a magnetic field pointing out of the back of the engine, perhaps backed up by additional coils once you are in space. It would be a bit like the hydrogen scoop on a Bussard ramjet, only not as big, and backwards.
"Judge rules that software cannot be patented" makes a good headline, but I think (IANAL) the actual issue is somewhat different.
I am in the UK. If something is patented in the US but not in the UK, I can try making and selling the patented item. I will not be liable to be sued in the US provided I do not sell stuff in the US itself. However, if you can prove that I have sold or exported stuff to the US or made the stuff in the US, then you can bring a case against me. When you bring that case, you can also sue for damages for all the overseas sales too. This seems to be an established practice in the US, rather than a piece of legislation.
Microsoft have a licence to make and sell something in the US. The discs are also copied abroad. If there isn't a case for patent infringement on US soil, then it will be very hard to bring a case against them. The case seems to hinge on what the concept of 'manufacture' is with a program. If it is in the coding or the compilation, then the 'golden disk' was made in the US, and Microsoft may be stuffed. If 'manufacture' means copying the disk and putting it in a box, then that happened (legally) in the US, or (illegally but outside US juristiction) abroad. If the program had been sent out over the net, then they could (and did, I think) argue that all the physical product had been made and sold overseas. However, the difference betweem e-mailing the program and taking it out on a disc is rightly not seen to be significant.
Sadly, this issue does not touch the actual patentibility of software.
From http://en.wikipedia.org/wiki/Gasoline#Energy_conte nt we see that a litre of petrol yeilds 30 MJ energy. Filling a tank of a small car with 40 litres of fuel takes perhaps 2 minutes to put 1.2 GJ into the the tank, which works out as a power input of 10 megawatts. A bit surprising for something so familiar, but there it is. If you are charging your car at home, you are unlikely to match that.
Yes, there may have been integrated circuits, but you tended to think of a 'red spot' OC71 rather than part of an integrated circuit. Transistor radio adverts boasted of the number of transistors - 7 for a cheap one, 12 for a good one. I used to have one of those "cat's whisker" sets with one. I feel old...
Yeah, I think the only real innovation here is describing the gates by Boolean concepts.
Naah. I have a copy of the 'Tomorrow's World' Annual somewhere from about 1967 showing binary log fluidic gates without moving parts. At the time, this was considered to be a possible alternative to silicon electronics for speed and compactness. People had also been anticipating MEMS technology, and saying mechanical calculators would eventually overtake electronics. Back then a transistor was still a can with three legs.
We cannot tell whether any particular fact is true. All we can do is to try and see how well anything we are told fits in with everything else we know. Suppose, for instance, we were told on a webpage that water freezes at 0 Celsius. We can get a thermometer and some water, and some ice, and do an experiment. All that tells us is that the people who write the web pages are somehow in collusion with the people who make thermometers. Or, at an even lower level, they are colluding with the people who write the dictionary terms for 'water' and 'thermometer'. Or the rules of grammar that determine that the description has a single, unambiguous distinction.
Okay, water does not always freeze at 0 celsius. Zero celsius is the triple point of water. When you actually do the experiments, or make your own observations, then you often find you have to refine the terms. I am not really talking about that. What I am trying to do is to make a distinction between what is 'true' and what is 'false'. We can define 'truth' so strictly that nothing we ever say is precisely 'true'. For the pruposes of this argument, I am going to relax a bit, and argue that statements can be 'true'.
How do we determine whether something is 'true'. Some scientific and mathematical statements are subject to proof or experiment, but we do not usually resort to this. With questions of historical fact, we can sometimes examine the raw evidence (but how 'raw' is that?). Most of the time, what we do is to see whether the new fact is compatible with what we already know. Knowledge has been likened to a boat which never comes into port: but is repaired by the crew using driftwood and materials found at sea. It would be difficult to completely remake the boat becaue it can never come into dock, but it an change over time by gradually expanding or replacing one component at a time. Over time, the whole boat's material may be replaced with new parts, and the whole crew may be replaced by their children, but the sense of their being a boat is preserved.
We should have some suspicion of everything we see and hear. Nothing is ruled above suspicion. However, you may remember the eposode of 'Kung Fu' where two adepts are guided by a venerable old man down a path where they are then robbed. They were both asked what they had learned from the event. The one who replied "trust no-one" was rejected from the monastery. "Expect the unexpected" was the better answer. Without some sort of discernment, there is no difference between the people who deny the Apollo project, and the people who deny the holocaust.
So, what is special about the web? Nothing, really, other than its newness and its versatility. We can post images and videos as well as text, but we also know we can manipulate images and fake videos. I can remember how authoratative some documents looked when printed out using variable-width fonts, when this was rare and expensive. Books tend to be trusted, because they are permanent, and therefore could have been criticised or edited as necessary. However, Erich von Daniken wrote books full of easily refutable facts. One of my favourites was how the island of Elephantine could have only been recognized as the exact shape of an elephant from a flying saucer. It isn't the shape of an elephant at all, as Google maps can show you - it got its name from the ivory trade. Going electronic has probably shortened the gap between posting something and posting the refutation, but the basic mechanism is the same.
Can we make something that gets people wary of clicking on random links, and falling for scams? That is where the scepticism is really needed.
Barium titanate is a structure called a spinel. It has oxygen ions packed in a face-centred cubic structure, with the barium and Titanium ions stuck on the holes between. Above a certain temperature, spinels are cubic. however, at lower temperatures, the structure can reduce its energy by breaking symmetry and squashing a bit down one of the cubic axes, becoming orthorhombic. This compression is not huge, but it is a lot bigger than the typical stretchings you get due to thermal expansion or mechanical stress.
Stick the spinel structure into a tin matrix and cool it. If you are ingenious about your choice of tin matrix, then the stress on the tin can actually get the spinel to change its shape in a way that opposes the bending, rather than going with it as you might expect. Tin is funny stuff - it also has a change in crystal structure on cooling from cubic to hexagonal (though at a much lower temperature) so I guess it is somehow squeezing the spinel in some anisotropic fashion and triggering the phase change.
This is ingenious stuff but it isn't really a high stiffness in the normal sense, any more then the compound pendulums you can somtimes find in grandfather clocks have a very low thermal expansion coefficient. Those have brass and steel rods which all have expansion coefficients, but they are put together in a way that makes the stotal expansion zero. Supposing you had a piezo crystal, with attached electronics that applied a voltage causing it to resist any force put upon it. You could make this infinitely stiff depending on your level of control, or even have it push pack on what is pressing on it.
So, back to your original question. It is heavy, and it only demonstrates the stiffness over a limited range. Bulk material stiffness is not usually important - you can make stiff structures like a cage of tubes by design. However, if you wanted to make some structure appear perfectly stiff, then some active control like the hypothetical piezo stuff I described earlier would probably be lighter and better. I would love to know what this ingenious stuff is for, but I don't think it is for space.
I thought I know most of my elements. I had heard of hafnium, but I had no idea where it was in the periodic table. It is in the transitions, towards the bottom left. You regularly hear of some 'breakthrough' semiconductor made from gallium, aluminium, arsenic, tellurium, buckytubes, Higgs bosons and lard, but this is hafnium with our old friend silicon. Not the first thing you might pick when trying to find a replacement for silicon dioxide. It has a large capture cross-section for thermal neutrons...
Which reminded me. Back in the 1930's, gadolinium was found to have a huge capture cross section for thermal neutrons. One of the people who discovered this managed to corner over 60% of the world's supply of gadolinium, but failed to make his fortune ( or so I remember. I have just been searching for some confirmation of this but no luck ). It is found at a few percent with zirconium, so it isn't exactly rare. However, if you happened to have a jar of the stuff on the shelf, you must be wondering what it is worth.
Almost a shame it is true. It would have made a magnificent scam.
That is just a database of patents. The Gillette company was sued by someone who did pretty much what Microsoft is doing now - they found an existing product that was not itself patented, and patented it. The Gillette company was either faced with ruin, or a court case where they had to prove that their product had existed prior to the patent filing. This was surprisingly hard thing to do. They searched novels and mewspaper articles for references to disposable razors. Everyone knew they existed, but finding hard, written evidence that could be presented in court was hard. They won the case, but the legal costs were high. The term "Gillette Defence" is now a generic term for this form of defence, and Phyrric victory.
Back in the 1980's, the UK patent search used to be pretty lightweight, the European patent search as more thorough but that was sometimes patchy, and the standard of patent searches was the US. In the intervening years, the US patent search quality has gone from the top to the bottom. Part of this is an inevitable response to the recent deluge of software patents, buisness practice patents, and other dubious stuff. Part of this is because the USA is perhaps 1/3 of the world market for most electronic and technological products, and so a single patent there is worth more than anywhere else.
How much searching ought you to do for a patent? If your country signed up to the international patent agreements, then for your patent to be valid, there must be no published or sold prior art anywhere in the world or in any language. This is an impossible search, so the assumption is always that any prior art search is incomplete. If all patent applications are incomplete, then some people may wonder why we start at all. You could just do a cursory search of the current online patents, and allow the application. Microsoft have lobbied for a more open system where patent application becomes easier, and the public community does more of the searching. Unfortunately, patent applications have titles, summaries, and patent indexes that make them easy to search, while products are not searchable in the same way. If you searched for prior art on the Microsoft product, then you would be very unlikely to discover BlueJ.
I do not think the public should be required to support the prior art searh effort, but if they are going to be enlisted, then they ought to have the right tools. What I would like to see is some searchable index of prior art or prior ideas. This could be classified the same way as patents. For my particular field of image colour transforms, I would list all the different ways in which would could generate and combine and apply different forms of colour transform, invert them, apply them, with all the different variations we could think of. Other people could generalize this list, or add more specific implementations, as a patent can cover a simplification as well as a refinement. We would include references to prior art where examples could be found. This would not stop existing patent applications for stuff we know has been around for ages, but it could frustrate all future attempts.
As a software writer and a filer of patents, I think we would be better off with no software patents. If we have to have them, let's make them good ones before they bring the whole patent system into disrepute.
Long chain molecules contain lots of carbon-carbon bonds. The polythene thing you get at the top of a six-pack of beer has lots of these chain molecules, but it is fairly weak. Stretch a bit of it, and you will see a sudden jump between the fat, unstretched material, and the skinnier, stretched material. The stretched stuff is a lot less stretchy. What you have done when you stretched the thing was to align the molecules, so you have chains of carbon-carbon bonds in the direction you have stretched the thing. Mylar - the stuff you sometimes find inside bicycle wheels and protective cloting is strengthened in this way.
That is only part of the secret. A diamond is made of carbon-carbon bonds in every direction, but you can shatter a diamond, and when you do the energies absorbed by the diamond are pretty tiny. If you want to make something tough, you will need some strategy for the thing to yeild and absorb energy. Metals yeild when they are stressed beyond a certain point, but they can still keep their strength. Carbon fibre materials can crack, but the carbon fibres have two strategies for resisting the crack. The fibres can separate from the glue matrix. If a fibre lies across the gap, then a lot of work is necessary to pull the fibtre free of the matrix as the crack opens. If the fibre lies along the crack, it can stop the crack becayse the crack may run around the fibre surface, and so end up with a blunt tip (the sharper the crack tip is, the more it concentrates the stress).
ness of the crack tip .
Another thing you will probably need in a sting is some ability to absorb energy without yeilding. Steel wire is a lot lighter for the same ability to support load, but climbers do not use it. The first thing a climber's rope needs to do is to absorb the energy from the falling climber. If it does not stretch, then the energy has to be absorbed over a small distance, so the force needed has to be that much bigger. Making where the threads so not go straight up and down have more 'give' in them.
Okay - I have cut a lot of corners in this explanation. There are scientific terms for strength, hardness, toughness, and things like that that are often confused in ordinary speech. However, I hope I have got across the basics - making long chain molecules isn't enough - you have to make them go up and down the thread; but not straight up and down or the thread will not stretch; and you have to glue them together with something sticky that absorbs energy as it yeilds. A spider's butt probably manages this because it is small, and the spinarets are a complex shape. All the bits seem do-able, but it's a good trick: people have been trying for many years, and we are not close yet. Maybe, there is another trick in there we haven't suspected yet.
PS: The process probably won't scale. So, you will have thousands of minature spider's butts, rather than one giant one.
In about 1968, IBM had an optical memory where about 2 Km of optical path was folded into something the size of a filing cabinet using mirrors, and 1 bit was circulating endlessly. Optical fibres transparent enought to do this did not happen for years.
This geta a brief mention in...
http://www-03.ibm.com/ibm/history/history/year_196 8.html
Wake us up when you actually have something wet...
on
Pictures of Titan's Lakes
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· Score: 1, Interesting
Mister Grumpy writes...
I don't think this is conclusive. As one of the other earlier posts said, they have taken the rough areas and coloured them rock colour, and taken the smooth areas and coloured them water colour. At the edge of these 'lake' features there are intermediate regions which are pretty flat and might be either shallow lake or a flat shore. Or something else completly different.
The article suggests we will in time know what we have. It is probably not sand because there aren't any dunes. If they are lakes, then the lake height ought to change with the seasons. In the meantime colouring it blue isn't really helping.
When I was a lad, Venus was believed to have huge oceans of soda water. Mars had a canal system. Tintin 'Destination Moon' book had underground ice on the moon. In the last fifty years we have visited all sorts of extraordinary places, and everywhere has turned out to be pretty dry. The lander shots of Titan looked just like a coastline, but that was not wet. There is an intriguing trickle of something in a crater on Mars. So far, the more we look, the less we find, and the more sceptical I get. Is this sort of thing really necessary to get funding for space exploration?
A sensible post on atmosphere-skippping aircraft. Thanks. Hope someone else reads it.
This sort of proposal has been around for a long time. Boeing had a proposal for a giant delta back about 1970. The problem has always been the need for different engine geometries for all the stages in the journey. You can use a complicated piggy-back aircraft design, which has been done - for example the Maia and Gaia flying boats, or the Hotol 2 to be launched from a giant Antonov - but is usually the last desparate attemt to make some record-breaking distance at any cost, rather than somethng commercial. What is really wanted is some variable geometry engine.
A few bits about Concorde...
Concorde flew at about twice the height of regular aircraft. There is a constant rain of debris from space that erodes paintwork and engine parts. If you fly higher, you meet less of this dust because it is falling faster through the thinner air. Concordes that had been flying for 25 years had a lot less of this wear than a commerical jets half its age. Weird, but true.
Concorde was allowed to jump the queue in holding patterns because it used up fuel fast in low level flight and didn't like carrying too much anyhow. A large delta craft might have to be given the same priveleges. You would know exactly when they would turn up because they won't be held up by headwinds, and you can reserve a slot for them.
The Concorde's jet engines had a variable geometry. They acted as conventional turbojet engines at low speeds, and at supersonic speeds, a standing shock wave decelerated and compressed the air on entry. This is a lot sompler than a scramjet, but not good enough for atmosphere skipping aircraft. The Skylon projects SABRE engine (http://en.wikipedia.org/wiki/SABRE) is a plausible alternative.
The original Concorde design was somewhat inefficient. It was like a sports car - tiny on the inside, and all engine. This is hardly surprising, because almost everything in it was unique. There were plans for a 'B' model in the late seventies (http://www.concordesst.com/concordeb.html). Supersonic flight need not always be a rich kids toy.
The aircraft will get hot on re-entry. Concorde got up to about 130c at the tip. A re-entry system will get a lot hotter. The Space Shuttle was designed in anticipation of some super high temperature materials that never happened, which is why it always has a lot of trouble with its tiles. If you made something a bit more aircraft like, you could probably keep the maximum surface temperatures below 1800c, and most surfaces way below that. Plus, the Space Shuttle is usually coming from higher up, and has more energy to lose.
Atmosphere skipping aircraft should be possible within 20-30 years. However, for something to happen, we have to have the will to build the things, and I can't see that happening just now. A pity - the Skylon is just so 'Flash Gordon'.
Countries have patent law to enable companies and individuals to recoup the costs of some venture. They safeguard the competitive edge that they have gained, and prevent others from merely copying and avoiding the venture costs. This protection is not given forever, but for a reasonable time over which the venture costs may be assumed to be recouped. Such protection should encourage innovation and wealth production.
One of the first patents in England was for colouring for stained glass. Anyone who could make a special colour either had to keep the recipie a secret, or risk their apprentices being hired by a rival. The Antykithera mechanism shows what happens when there is no patent law - the technology and science for making geared computers for complex calculations was so well hidden that it was totally lost and forgotten. We have no odea how many of these machines there might have once been.
Patenting does not necessarily mean you, personally, had a good idea. If you funded some shipping venture, went abroad and studied, and brought back a useful process (silk production, bone china, etc) then you could patent that. This survived into UK law up until about 1968. These days, travel and communications have made travel expense as a basis for a patent obselete. If we go to the stars, maybe it will come back again.
The US patent system had recently allowed patents on software, and buisness practices. The patents seem to have little to do with an extended piece of research, or travelling. The actual venture costs seem to be in the costs of achieving a patent portfolio. This is a venture like any of the previous examples through history. However, it is not making wealth for the general society any more than employing people to dig holes and others to fill them in again contributes to general employment. The rest of the patenting world has been reluctant to accept these changes just because they do not seem compatible with the aims of patents in general.
If anything, the real problem lies with the US patent department. I used to work on patents for Canon at the time when software patents were becoming possible - first in a programmed machine, then on media combined with a programmable machine, then on the media to be combined with a suitable machine, and so forth. Large companies may not want to plunge huge resources into building a software patent portfolio, but when software patents become possible, they must join in the land grab or lose out. Microsoft is doing the same thing that any large company would do.
Slashdot Mirror
In a SCRAMjet, we are not accelerating and squashing the air like the Olympus engines on Concorde, but trying to get the thrust from the air as it goes through. I had skipped this bit to keep my note short and accessible to people who might be confused by the original article. Rather lazy writing style, and serves me right for being caught out.
Thanks.
The chess ranking is typically a 3-digit figure. Given two chess players, you can work out approximate odds of one winning from the difference in these figures. The figures are compiled from the games people have won, and the ranks of people they have played against. As in multi-choice tests, each individual question or game has a wright (win) and a wrong (lose) solution, and a stalemate (not filling in anything) option. From this we can estimate ranks of people we have not met; we can estimate ranks of people in history; we can even estimate corrections for ranks between cultures. For instance in the 19th century, how might a woman chess player in London (where the culture did not encourage chess) rank against a man from Prague (where cafes typically had chess boards in the tabletop, and most people played with friends and strangers in their lunch hours) had their backgrounds been equal, and assuming a native talent for chess is spread equally? This last point is not obvious - the differences between London and Prague and between women and men may not be wholly cultural, but the others can discuss that ad et ultra nauseam.
No-one designed chess with a perfect solution, and yet we can rank people. The IQ tests started from a similar point. People did not understand what intelligence was, exactly, but if they made tests that seemed to be testing the right sort of thing, and got the best people to design the next round of tests, then it was hoped that an incisive test for intelligence would evolve, even though no-one had defined what intelligence was. Unfortunately, in the early days, what was being tested as 'intelligence' was probably better named "how like minded are you to the white male that designed the test". The test can be as exacting as a chess ranking if you do enough tests, but the figure is less useful because it is not a measurement of something abstract and useful (unless you were IBM in the sixties, looking for white males with short hair that would sing the company song, in which case it was perfect).
There is a further downside to IQ tests. If you sit and stare at them, you can often reason a second or third possible answer using different readoning. I also have a problem with forms that means I think long and hard about the answer, and then tick the wrong box. The trick seems to be to work really quickly, and let your instincts drive your answer. I have only ever done about three IQ tests, and all of these were done ages ago for job applications to computer companies. The last one must have been twenty five years ago. We had two hours and 300 questions. I deliberately hammered through the questions, and handed the paper in after 40 minutes to avoid the temptation of fiddling with the answers. Incredibly, this seemed to cure my usual error rate with forms, and I got a perfect score. I wasn't any smarter that day - I just happened to be in the zone, I guess.
Didn't get the job, though. They thought I was too scary.
Thinking about the original post, though. The guy claimed that a multi-choice was 'fraudulent'. Isn't 'fraud' where someone is trying to deceive someone else? Multi-choice questions are an attempt to separate the test for the presence or absence of knowledge from the talents of presentation (good handwriting, confident presentation style, etc), but often flawed by laziness in trying to pass off examination skills to a computer. A good multi-choice questionnaire would have to be much longer than such tests usually are to reliably separate the thing you are trying to measure from the noise (think how much mesurement goes into a chess ranking, for example). But 'fraudulent'? And this was supposed to be a legal exam? I have my doubts about the original posting. Interesting subject, though.
Scramjets look good on paper. The thin air coming in is compressed by a series of standing shock waves. Unfortunately, the geometry of these shock waves can easily be upset by small distortions in the engine, which in turn can lead to changes in the stresses with in the engine, which - to cut a long story short - can mean the engine spectacularly demolishes itself when faced with real bits of atmosphere with unpredictable air currents. I found the flight time in...
http://www.abc.net.au/science/slab/hyshot/default. htm
It may not sound like much, but six seconds is very respectable for a scramjet. Yay!
There is a lot of touting about how this would get you from London to Sydney in 40 minutes and stuff. I am not sure how true or economical this is, even if scramjets can be made safe. When you are flying fast, you can either take your oxidant with you (as rockets do) or you can scoop it up as you go along. Scooping it up as you go along means taking in air that was initially at rest and getting to move at the speed the engine is currently going. As only 20% of the air is actually the oxygen you want, this is not necessarily an effective thing to do. It becomes most effective when the oxidant (oxygen) is a lot heavier than the reductant (fuel - and hydrogen is particularly light), so scooping it up as you go takes a lot off the take-off weight.
The other London to Sydney option is to get just beyond the atmosphere using a conventional rocket, then going ballistic and weightless for the main distance, and re-entering and gliding, a lot like the space shuttle. While being weightless is fun, being weightless for 20 minutes makes most people puke, so a large passenger jet might skip the atmosphere and retain a little gravity. A scramjet might be used for this.
Nevertheless, yay!
We were at a bus stop. Someone across the road came out of a blcok of flats, and tried putting a key into a car. The alarm went off, ewven though the key had unlocked the door. The person opened the bonnet, and pulled, and hit, and eventually blessed silence returned. He then managed to drive off. He could have been stealing the car. We did not think so, but he might have been. If you see a car alarm going off, do you rush to the defence of someone else's property? Naah. Even policemen who stopped when they saw me struggling with a car door and an alarm in a car park moved on when I gave them a wave and a I-can't-help-it shrug.
I have a Jeep Cherokee (right hand drive). This had an alarm which went off even though the door could be opened, which means the bonnet could be opened, and the alarm could be disconnected. If the side window is left a crack open, the alarm can go off when a gust of wind hits it just so. It then stays on until it is smashed by infuriated neighbours (this is what did for it eventually) or the battery is flat, whereupon the doors all unlock. The car is dead, so I ring home for a jump start. We connect up the batteries, whereupon the doors lock again, locking the keys inside, and the alarm sounds until the battery is flat again, or I rip the wires off. Stupid, stupid, stupid!!!
I believe BMW have an even finer version of the phone battery alarm trick. If you leave the car in the garage, the alarm system is still on. After about two weeks the battery voltage may dip beneath 11v. The alarm system reckons that someone may be trying to run down the battery, so it flashes the lights, sounds the horn, and uses up the rest of the battery in in the garage. Then it unlocks all the doors. Hooray.
Just back from Tinsel Town after talking to some of the dudes in the article. Still jetlagged, so it feels a bit unreal reading about it in Slashdot. Still, I'll do my best to explain why things are the way they are...
A film is not often made by a single body. If you are shooting to film, then this will get handled by an editorial department. You may have a fast telecine scan for reviewing the material as dailies. Some of these scans may be used as low-resolution proxies for initial grades. Some chosen bits of film may get re-scanned on a slower pin-resolution scanner for inclusion in the final film. Artificial rendered scenes and special effects may be done by specialist houses, then composited in a post-production house. Your film may have 25 4K images per second in the final version, but the data used to generate it is scattered over the place - if you think a good IT department should be backing all this up, then you haven't worked on a film, my friend. As deadlines approach, people may be working stupid hours, and filling up all the available storage. Then the film gets released, and either makes a billion dollars or doesn't. Either way, the tension is off, people take holiday and zonk out. Nobody will be picking over the cutting-room floor or its digital equivalent looking for things that might be useful twenty years from now. By the time people are back from holiday, they don't know or don't care.
Your end product may be big reels of negative film that you send to a film lab to make prints for cinemas. The lab should keep the golden master clean, and make most of the prints from a second copy. This would be a sensible time to make an archival print of the film. The lab can transfer the whole thing to black and white film. Black and white film does not fade, like conventional colour film does, even in the can. You are getting the print lab to do a pretty full backup of the released film when your people have all gone on holiday. These days you need to back up other stuff. The soundtrack is digital. You will have extra data for the releases in different formats (5:4 TV, 16:9 widescreen, IMAX, etcetera). Still, it is a lot better than nothing. But it is not often done.
The other think is to know what to archive. Very little of the newsreel film I had to sit though as a child to get to the cartoon has survived. Key stuff like the Queen's Coronation or the outbreak of WW2 was clearly history, and put on a special shelf, but little of the day to day stuff survives. There is one cache that survived when a cinema closed, and the tins of newsreel went into landfill. The cinema was in Alaska; the landfill was permafrost, and the film was kept in near ideal refrigetrated conditions. Apart from this fluke, it has probably all gone.
There will probably be digital solutions in time. Increasingly, as we have to manage more different sorts of digital data, there is a need to organize and track everything, which ought to mean it is possible to archive all the essential bits that go into any production. Many other people have posted on the problems of knowing what is on (say) a FAT16 Windows 3.1 disk in some 1980's image format. You can keep copying the data to overcome the degradation of the physical medium, but you still have to know what it means. I know of a system for archiving film images, where the people who did the archiving left the company, and one of them took the laptop with them that had the archiving software, so the ability to read the archives went with them. Do you archive the archiving system? Then, do you archive the system that archived that? Yes - basically, that is exactly what people are proposing to do. But it takes a bit of organizing, and we are not there yet.
Film, on the other hand, has visible images. The 35mm format has remained readable for over 100 years. Even where nitrate stock has flowed over time, we still know what shape it ought to have been. Sometimes we can get something back if we want it badly enough.
A simple analogue solution may be to
Stick to the half-silvered mirror, ya perv.
We should not believe all we read in the web. We should not believe all we read in books either. Some stuff is accurate, some is mistaken, some is made up. Unless it is all chaos, and will always be chaos, we believe that in time the errors should be found and be corrected. Sometimes people come across a large chunk of fakery. The discrediting of the work of Dr. V.J. Gupta cast doubt on much of the geolegy of the Himalayas for the last 20 years ( see http://www.scientificvalues.org/newsnovember2002.h tml ). Nevertheless, we sift through the rubble, and find out what can be kept, and what can't. Or we sit in the chaos.
Wikipaedia relies on voluntary contributions. Take a cross-section of the internet who will do somethig for nothing, and you will always get a generous helping of dross - spammers, trolls, phishers, fundamentalists, vandals, and general nutbars - with, maybe, a tiny fraction of people who have understood a subject, and simply want to share that understanding with others. I admire the spirit that believes that this tiny fraction may prevail. The fact that someone with suspect credentials is found out, and their work is given a second look, shows that the thing is working. You see this when newspapers have to print a retraction, or TV programs broadcast a correction. If you didn't see this, then you should worry.
It seems there are a lot of people out there with heart and spleen problems. Good lord, but there is some serious vitriol there. Who are all these people without fault, jostling to get their stone in first? What makes them think Jimbo Wales owes them a personal apology? Who elected you lot the Guardians of Truth, eh? Sheesh...
So, my grateful thanks, Jimbo and all Wikipaedians, for a most useful and valuable webpage.
Okay - I have probably earned myself a good flaming in Internet Hell for that heresy. Might as well do a proper sheep-for-a-lamb job. This next bit goes out to EssJay...
Hi, EssJay. I am not in your field, so I can't read what you wrote, but your friends seem to like you and speak well of you. Cheer up. You don't need a doctorate. I have got one, and it's not a lot of use. Dr. V.J. Gupta had a doctorate. If your contributions are good - and I do hope they are - then pick another name, and come back a bit later when the legions of shit-throwing monkeys have found something else to amuse them. Do no harm, do a bit of good when you can, and we'll all get there in the end.
If you assess risk by mass, then you can blame global warming on cows. Methane reduces ozone. Cows fart out lots of methane and other stuff. By mass, they produce much more than all aircraft. This is probably wrong, but widely quoted. But aircraft chuck their stuff out in the upper atmosphere, where it gets further and probably has a lot more effect.
We cannot do the traditional experiment - have two worlds, one with a population and one without, and measure the differences. However, we can look at the natural experiments in the solar system. If the icecaps of Mars have shrunk at the same times as the icecaps of Earth, then there may be a link. If we think there is a link, then we try and gather more evidence. This is what science does. It's a bit dull, and it rarely moves as fast as we like on important issues. It may be more fun to report on academic rows, controversies, and consparacies. But they really don't help much in the long run.
Unfortunately, junk DNA is not a place for information. Unlike most 'junk' things, junk DNA is often very clean repeated patterns that cannot contain much information. In general, smaller cells have less junk DNA, suggesting that it may have some structural purpose. The amino acid set is a nice molecular lego for bulding all sorts of shapes, as well as storing information. There may be a repository, but it isn't in junk DNA.
If you replace the diffusion vacuum pump and rotary backing pump with a modern turbomolecular pump, then you don't have the warm-up time or the noise. If you have a small aperture, and pump the thing hard enough, then a 25KeV beam will travel a few mm in air. Use a magnetic field to turn the beam just before the aperture and the air going through the aperture won't roar straight up the electron optics. People have viewed living cells under electron microscopes so having a high vacuum electron optics with a small open end is possible. A bit of air can also avoid the charging problems, which is whjy SEM specimens are usually coated in gold first.
If you can sweep an electron beam over the surface you can get the SEM view of it, but you can also use the electron beam to evaporate and ionize material, which can then go into a mass spectrometer. You can look for X-rays, electron diffraction, and so forth. There's lots of stuff you can stick onto a SEM that could probably be minaturized down to the cassette player size of the Tricorder.
It's not 'life form readings at 500 meters' but it's a start.
A conventional rocket motor chucks out lots of hot, ionized gas. In the lower atmosphere, this comes out as a long, thin flame. As the atmosphere gets thinner, the gas can fly out sideways. You have the paraboloidal bells at the base of the rocket with try an convert this sideways motion of the plasma into downward motion, so you get as much forward momentum as you can. However, the gas in the bells is colliding with itself as much as with the engine walls, so you will still get stuff spraying out sideways. What you would need is an impracticably huge bell shape so the gases thin out to the Knudsden regime before bounding specularly off the walls. However, you could steer the heavy positive ions backwards with a magnetic field pointing out of the back of the engine, perhaps backed up by additional coils once you are in space. It would be a bit like the hydrogen scoop on a Bussard ramjet, only not as big, and backwards.
Then I read the 'explanation'. Meh.
I am in the UK. If something is patented in the US but not in the UK, I can try making and selling the patented item. I will not be liable to be sued in the US provided I do not sell stuff in the US itself. However, if you can prove that I have sold or exported stuff to the US or made the stuff in the US, then you can bring a case against me. When you bring that case, you can also sue for damages for all the overseas sales too. This seems to be an established practice in the US, rather than a piece of legislation.
Microsoft have a licence to make and sell something in the US. The discs are also copied abroad. If there isn't a case for patent infringement on US soil, then it will be very hard to bring a case against them. The case seems to hinge on what the concept of 'manufacture' is with a program. If it is in the coding or the compilation, then the 'golden disk' was made in the US, and Microsoft may be stuffed. If 'manufacture' means copying the disk and putting it in a box, then that happened (legally) in the US, or (illegally but outside US juristiction) abroad. If the program had been sent out over the net, then they could (and did, I think) argue that all the physical product had been made and sold overseas. However, the difference betweem e-mailing the program and taking it out on a disc is rightly not seen to be significant.
Sadly, this issue does not touch the actual patentibility of software.
From http://en.wikipedia.org/wiki/Gasoline#Energy_conte nt we see that a litre of petrol yeilds 30 MJ energy. Filling a tank of a small car with 40 litres of fuel takes perhaps 2 minutes to put 1.2 GJ into the the tank, which works out as a power input of 10 megawatts. A bit surprising for something so familiar, but there it is. If you are charging your car at home, you are unlikely to match that.
Yes, there may have been integrated circuits, but you tended to think of a 'red spot' OC71 rather than part of an integrated circuit. Transistor radio adverts boasted of the number of transistors - 7 for a cheap one, 12 for a good one. I used to have one of those "cat's whisker" sets with one. I feel old...
Naah. I have a copy of the 'Tomorrow's World' Annual somewhere from about 1967 showing binary log fluidic gates without moving parts. At the time, this was considered to be a possible alternative to silicon electronics for speed and compactness. People had also been anticipating MEMS technology, and saying mechanical calculators would eventually overtake electronics. Back then a transistor was still a can with three legs.
Okay, water does not always freeze at 0 celsius. Zero celsius is the triple point of water. When you actually do the experiments, or make your own observations, then you often find you have to refine the terms. I am not really talking about that. What I am trying to do is to make a distinction between what is 'true' and what is 'false'. We can define 'truth' so strictly that nothing we ever say is precisely 'true'. For the pruposes of this argument, I am going to relax a bit, and argue that statements can be 'true'.
How do we determine whether something is 'true'. Some scientific and mathematical statements are subject to proof or experiment, but we do not usually resort to this. With questions of historical fact, we can sometimes examine the raw evidence (but how 'raw' is that?). Most of the time, what we do is to see whether the new fact is compatible with what we already know. Knowledge has been likened to a boat which never comes into port: but is repaired by the crew using driftwood and materials found at sea. It would be difficult to completely remake the boat becaue it can never come into dock, but it an change over time by gradually expanding or replacing one component at a time. Over time, the whole boat's material may be replaced with new parts, and the whole crew may be replaced by their children, but the sense of their being a boat is preserved.
We should have some suspicion of everything we see and hear. Nothing is ruled above suspicion. However, you may remember the eposode of 'Kung Fu' where two adepts are guided by a venerable old man down a path where they are then robbed. They were both asked what they had learned from the event. The one who replied "trust no-one" was rejected from the monastery. "Expect the unexpected" was the better answer. Without some sort of discernment, there is no difference between the people who deny the Apollo project, and the people who deny the holocaust.
So, what is special about the web? Nothing, really, other than its newness and its versatility. We can post images and videos as well as text, but we also know we can manipulate images and fake videos. I can remember how authoratative some documents looked when printed out using variable-width fonts, when this was rare and expensive. Books tend to be trusted, because they are permanent, and therefore could have been criticised or edited as necessary. However, Erich von Daniken wrote books full of easily refutable facts. One of my favourites was how the island of Elephantine could have only been recognized as the exact shape of an elephant from a flying saucer. It isn't the shape of an elephant at all, as Google maps can show you - it got its name from the ivory trade. Going electronic has probably shortened the gap between posting something and posting the refutation, but the basic mechanism is the same.
Can we make something that gets people wary of clicking on random links, and falling for scams? That is where the scepticism is really needed.
Barium titanate is a structure called a spinel. It has oxygen ions packed in a face-centred cubic structure, with the barium and Titanium ions stuck on the holes between. Above a certain temperature, spinels are cubic. however, at lower temperatures, the structure can reduce its energy by breaking symmetry and squashing a bit down one of the cubic axes, becoming orthorhombic. This compression is not huge, but it is a lot bigger than the typical stretchings you get due to thermal expansion or mechanical stress.
Stick the spinel structure into a tin matrix and cool it. If you are ingenious about your choice of tin matrix, then the stress on the tin can actually get the spinel to change its shape in a way that opposes the bending, rather than going with it as you might expect. Tin is funny stuff - it also has a change in crystal structure on cooling from cubic to hexagonal (though at a much lower temperature) so I guess it is somehow squeezing the spinel in some anisotropic fashion and triggering the phase change.
This is ingenious stuff but it isn't really a high stiffness in the normal sense, any more then the compound pendulums you can somtimes find in grandfather clocks have a very low thermal expansion coefficient. Those have brass and steel rods which all have expansion coefficients, but they are put together in a way that makes the stotal expansion zero. Supposing you had a piezo crystal, with attached electronics that applied a voltage causing it to resist any force put upon it. You could make this infinitely stiff depending on your level of control, or even have it push pack on what is pressing on it.
So, back to your original question. It is heavy, and it only demonstrates the stiffness over a limited range. Bulk material stiffness is not usually important - you can make stiff structures like a cage of tubes by design. However, if you wanted to make some structure appear perfectly stiff, then some active control like the hypothetical piezo stuff I described earlier would probably be lighter and better. I would love to know what this ingenious stuff is for, but I don't think it is for space.
Which reminded me. Back in the 1930's, gadolinium was found to have a huge capture cross section for thermal neutrons. One of the people who discovered this managed to corner over 60% of the world's supply of gadolinium, but failed to make his fortune ( or so I remember. I have just been searching for some confirmation of this but no luck ). It is found at a few percent with zirconium, so it isn't exactly rare. However, if you happened to have a jar of the stuff on the shelf, you must be wondering what it is worth.
Almost a shame it is true. It would have made a magnificent scam.
That is just a database of patents. The Gillette company was sued by someone who did pretty much what Microsoft is doing now - they found an existing product that was not itself patented, and patented it. The Gillette company was either faced with ruin, or a court case where they had to prove that their product had existed prior to the patent filing. This was surprisingly hard thing to do. They searched novels and mewspaper articles for references to disposable razors. Everyone knew they existed, but finding hard, written evidence that could be presented in court was hard. They won the case, but the legal costs were high. The term "Gillette Defence" is now a generic term for this form of defence, and Phyrric victory.
How much searching ought you to do for a patent? If your country signed up to the international patent agreements, then for your patent to be valid, there must be no published or sold prior art anywhere in the world or in any language. This is an impossible search, so the assumption is always that any prior art search is incomplete. If all patent applications are incomplete, then some people may wonder why we start at all. You could just do a cursory search of the current online patents, and allow the application. Microsoft have lobbied for a more open system where patent application becomes easier, and the public community does more of the searching. Unfortunately, patent applications have titles, summaries, and patent indexes that make them easy to search, while products are not searchable in the same way. If you searched for prior art on the Microsoft product, then you would be very unlikely to discover BlueJ.
I do not think the public should be required to support the prior art searh effort, but if they are going to be enlisted, then they ought to have the right tools. What I would like to see is some searchable index of prior art or prior ideas. This could be classified the same way as patents. For my particular field of image colour transforms, I would list all the different ways in which would could generate and combine and apply different forms of colour transform, invert them, apply them, with all the different variations we could think of. Other people could generalize this list, or add more specific implementations, as a patent can cover a simplification as well as a refinement. We would include references to prior art where examples could be found. This would not stop existing patent applications for stuff we know has been around for ages, but it could frustrate all future attempts.
As a software writer and a filer of patents, I think we would be better off with no software patents. If we have to have them, let's make them good ones before they bring the whole patent system into disrepute.
Long chain molecules contain lots of carbon-carbon bonds. The polythene thing you get at the top of a six-pack of beer has lots of these chain molecules, but it is fairly weak. Stretch a bit of it, and you will see a sudden jump between the fat, unstretched material, and the skinnier, stretched material. The stretched stuff is a lot less stretchy. What you have done when you stretched the thing was to align the molecules, so you have chains of carbon-carbon bonds in the direction you have stretched the thing. Mylar - the stuff you sometimes find inside bicycle wheels and protective cloting is strengthened in this way.
That is only part of the secret. A diamond is made of carbon-carbon bonds in every direction, but you can shatter a diamond, and when you do the energies absorbed by the diamond are pretty tiny. If you want to make something tough, you will need some strategy for the thing to yeild and absorb energy. Metals yeild when they are stressed beyond a certain point, but they can still keep their strength. Carbon fibre materials can crack, but the carbon fibres have two strategies for resisting the crack. The fibres can separate from the glue matrix. If a fibre lies across the gap, then a lot of work is necessary to pull the fibtre free of the matrix as the crack opens. If the fibre lies along the crack, it can stop the crack becayse the crack may run around the fibre surface, and so end up with a blunt tip (the sharper the crack tip is, the more it concentrates the stress). ness of the crack tip .
Another thing you will probably need in a sting is some ability to absorb energy without yeilding. Steel wire is a lot lighter for the same ability to support load, but climbers do not use it. The first thing a climber's rope needs to do is to absorb the energy from the falling climber. If it does not stretch, then the energy has to be absorbed over a small distance, so the force needed has to be that much bigger. Making where the threads so not go straight up and down have more 'give' in them.
Okay - I have cut a lot of corners in this explanation. There are scientific terms for strength, hardness, toughness, and things like that that are often confused in ordinary speech. However, I hope I have got across the basics - making long chain molecules isn't enough - you have to make them go up and down the thread; but not straight up and down or the thread will not stretch; and you have to glue them together with something sticky that absorbs energy as it yeilds. A spider's butt probably manages this because it is small, and the spinarets are a complex shape. All the bits seem do-able, but it's a good trick: people have been trying for many years, and we are not close yet. Maybe, there is another trick in there we haven't suspected yet.
PS: The process probably won't scale. So, you will have thousands of minature spider's butts, rather than one giant one.
In about 1968, IBM had an optical memory where about 2 Km of optical path was folded into something the size of a filing cabinet using mirrors, and 1 bit was circulating endlessly. Optical fibres transparent enought to do this did not happen for years. This geta a brief mention in... http://www-03.ibm.com/ibm/history/history/year_196 8.html
I don't think this is conclusive. As one of the other earlier posts said, they have taken the rough areas and coloured them rock colour, and taken the smooth areas and coloured them water colour. At the edge of these 'lake' features there are intermediate regions which are pretty flat and might be either shallow lake or a flat shore. Or something else completly different.
The article suggests we will in time know what we have. It is probably not sand because there aren't any dunes. If they are lakes, then the lake height ought to change with the seasons. In the meantime colouring it blue isn't really helping.
When I was a lad, Venus was believed to have huge oceans of soda water. Mars had a canal system. Tintin 'Destination Moon' book had underground ice on the moon. In the last fifty years we have visited all sorts of extraordinary places, and everywhere has turned out to be pretty dry. The lander shots of Titan looked just like a coastline, but that was not wet. There is an intriguing trickle of something in a crater on Mars. So far, the more we look, the less we find, and the more sceptical I get. Is this sort of thing really necessary to get funding for space exploration?
This sort of proposal has been around for a long time. Boeing had a proposal for a giant delta back about 1970. The problem has always been the need for different engine geometries for all the stages in the journey. You can use a complicated piggy-back aircraft design, which has been done - for example the Maia and Gaia flying boats, or the Hotol 2 to be launched from a giant Antonov - but is usually the last desparate attemt to make some record-breaking distance at any cost, rather than somethng commercial. What is really wanted is some variable geometry engine.
A few bits about Concorde...
Concorde flew at about twice the height of regular aircraft. There is a constant rain of debris from space that erodes paintwork and engine parts. If you fly higher, you meet less of this dust because it is falling faster through the thinner air. Concordes that had been flying for 25 years had a lot less of this wear than a commerical jets half its age. Weird, but true.
Concorde was allowed to jump the queue in holding patterns because it used up fuel fast in low level flight and didn't like carrying too much anyhow. A large delta craft might have to be given the same priveleges. You would know exactly when they would turn up because they won't be held up by headwinds, and you can reserve a slot for them.
The Concorde's jet engines had a variable geometry. They acted as conventional turbojet engines at low speeds, and at supersonic speeds, a standing shock wave decelerated and compressed the air on entry. This is a lot sompler than a scramjet, but not good enough for atmosphere skipping aircraft. The Skylon projects SABRE engine (http://en.wikipedia.org/wiki/SABRE) is a plausible alternative.
The original Concorde design was somewhat inefficient. It was like a sports car - tiny on the inside, and all engine. This is hardly surprising, because almost everything in it was unique. There were plans for a 'B' model in the late seventies (http://www.concordesst.com/concordeb.html). Supersonic flight need not always be a rich kids toy.
The aircraft will get hot on re-entry. Concorde got up to about 130c at the tip. A re-entry system will get a lot hotter. The Space Shuttle was designed in anticipation of some super high temperature materials that never happened, which is why it always has a lot of trouble with its tiles. If you made something a bit more aircraft like, you could probably keep the maximum surface temperatures below 1800c, and most surfaces way below that. Plus, the Space Shuttle is usually coming from higher up, and has more energy to lose.
Atmosphere skipping aircraft should be possible within 20-30 years. However, for something to happen, we have to have the will to build the things, and I can't see that happening just now. A pity - the Skylon is just so 'Flash Gordon'.
One of the first patents in England was for colouring for stained glass. Anyone who could make a special colour either had to keep the recipie a secret, or risk their apprentices being hired by a rival. The Antykithera mechanism shows what happens when there is no patent law - the technology and science for making geared computers for complex calculations was so well hidden that it was totally lost and forgotten. We have no odea how many of these machines there might have once been.
Patenting does not necessarily mean you, personally, had a good idea. If you funded some shipping venture, went abroad and studied, and brought back a useful process (silk production, bone china, etc) then you could patent that. This survived into UK law up until about 1968. These days, travel and communications have made travel expense as a basis for a patent obselete. If we go to the stars, maybe it will come back again.
The US patent system had recently allowed patents on software, and buisness practices. The patents seem to have little to do with an extended piece of research, or travelling. The actual venture costs seem to be in the costs of achieving a patent portfolio. This is a venture like any of the previous examples through history. However, it is not making wealth for the general society any more than employing people to dig holes and others to fill them in again contributes to general employment. The rest of the patenting world has been reluctant to accept these changes just because they do not seem compatible with the aims of patents in general.
If anything, the real problem lies with the US patent department. I used to work on patents for Canon at the time when software patents were becoming possible - first in a programmed machine, then on media combined with a programmable machine, then on the media to be combined with a suitable machine, and so forth. Large companies may not want to plunge huge resources into building a software patent portfolio, but when software patents become possible, they must join in the land grab or lose out. Microsoft is doing the same thing that any large company would do.