You don't just want a circular object. You want a series of circular rings at the right intervals to interfere and give an intensity peak where the camera is. This s not as efficient as using a giant mirror, but it could be a lot lighter, and less sensitive to vibrations or distortions out of the plane of the disc.
Saturn has a lot of rings. The shepherd satellites within the rings make some pretty complex patterns. It may be possible to use the natural structures. Or maybe we could add a few small moons of our own. The camera would have to lie above or below Saturn to look at the unlit side of the rings.
Yes, this is how science works. It is obvious that talking will help people make flint tools. We all know that. But how do we know that? Saying 'it's obvious' is not helpful. It is also obvious that you can get better at making tools when you can watch someone who is good at it. But you can get plenty of people how have never chipped flint tools, and see how much better they are when they watch someone, when they mutely interact with someone, and when they talk. Some gifted people can pick up musical instruments just by watching, but making flint tools seems to be helped a lot by language.
The article also says that this is suggestive, but could not be considered a proof. They know they have not got ancient people to experiment on. It is not practical to try the same tests with a mammoth hunt. It's not a time machine, but we use what we have.
Then you get a +5 'insightful' mark-up for jeering at it.
It's a high energy plasma out there, how will you get any structure in that?
Actually, the sun has a lot of structure in its magnetic field. This is not just complex in the way Earth's weather is, meaning is is unpredictable. It has long term structures, such as the 11-year sunspot cycle.
I really doubt if these magnetic fields are sentient at all, and certainly not sentient as we understand it. The world's phone system has a similar complexity to the human brain, but if that was sentient, it would be hard to imagine what it thought about, as it has no obvious eyes and ears.
However, suppose we wanted to delay the supernova of our sun. We could do this if we had the technology by injecting fusible hydrogen from the sun's surface into the core at the same rates that it was consumed. This would require completely bonkers apparatus, but the physics is good. Supposing the best and most efficient way of doing this was to influence the magnetic field of the sun so that it did this itself. Suppose the best way of doing that was to artificially induce intelligence in these plasma fields, so it could do this without regulation...
That is a lot of supposes. But in my mind, I think if civilization lasts for astronomical time-scales, this is less ridiculous then expecting to detect them by their leaked unfocussed long-period radio waves, which is what SETI is looking for. I wouldn't spend any money on it, but the thinking doesn't hurt.
If you have your screen at R meters away, add (1/R) to your lens strength in diopters. Diopters are 1.0/focal_length in meters. That will give you the same comfortable image_distance at your eye when looking at your screen.
Suppose you have your monitor 0.5 of a meter away, and you use -5.0 diopter glasses because you are short-sighted. You add (1/0.5) = 2.0 to -5.0 diopters and get -3.0 diopters. The person who had -5.0 diopters and used -3.5 diopter lenses for computing work probably uses a screen 2/3 meters away. If you are short-sighted, the diopter values should get smaller in magnitude; if you are long-sighted, the diopter value will get bigger.
Add 2 diopters if your screen is 50 cm away.
Add 1.5 if your screen is 67 cm away.
Add 1 if your screen is 1m away (a bit far, but maybe you have a big monitor)
Hot damn, that school physics is actually good for something! Too bad they had to black out the lab to show us, and we all fell asleep. Now, all I need is some frictionless pulleys and massless string...
Bird strikes can be dangerous if one goes into the engine. This rarely downs an aircraft unless you have a two-engined aircraft and both engines get hit at the same time. Remember the plane that landed in the Hudson after a double bird strike? That was an Airbus A320.
Whether this is a significant risk depends on what the drone flyer is trying to do. If they are trying to get close-up pictures of aircraft then they are probably no bigger risk than birds. If they are aiming for the engines because they want to take down an aircraft, then there is a significant risk, particularly of the drone is carrying some load designed to do damage. Why would someone do this? I dunno. Why do people use laser pointers to try and blind pilots? Maybe not terrorism: some people are just dicks.
What do we do? Well, if they are radio-controlled then we can pinpoint the controller by radio. It would be a nice problem to design a set of drones that can triangulate the source of a radio signal, home in on it, and track what they find.
The actual article is a bit shallow on detail, but here's my interpolation...
Infra-red is quite a broad bit of the spectrum. It starts at about 800nm as light we can't quite see, and security cameras use this band with an infra-red illuminant. If we go down to about 2000nm, we are into the mid-band where some IR cameras operate. These can see hot objects but cannot people by their radiated body heat. There is a gap at about 3500nm where water vapour absorbs and emits, and cameras do not work well. Then there is another band at about 7000nm where the thermal cameras that can pick up body heat work. The cooler you are, the greater fraction of long wavelength you emit. (NB: if the exact wavelengths are important, please check as I am typing this off the top of my head).
Most black paints absorb all infra-red wavelengths equally. Some white paints will absorb the far-infra-red. What you want, and what I think they have done is to make somethng that reflects down to 2000nm, and then absorbs beyond about 400nm. This will reflect a lot of the heat from the sun, but will still radiate the heat from the building.
Does it work? Will it still work when it is dirty? I don't know, but at least it does not violate any thermodynamic principles.
I live in a large village or small town. I get a lot of power outages. Some of these last for hours. Most of the rest of the village does not get these - just a small clump of houses around the church. Our cable comes underground from Hemel Hempstead. The rest of the village gets power from the pylons that run alongside the M1. We can claim back money for the power outages.
I would imagine our group of houses has problems because (a) we are at the end of a spur (b) we got electricity before anyone else, and before the M1 was built, so our lines are particularly old, and (c) the power distribution network has probably shifted, and our little bit has not been altered to reflect the changes. If you live out in the sticks, you become more vulnerable: I remember a house where the power used to trip out when the transport cafe about a mile away turned off their grills last thing at night. One of the downsides of generating your own power may be that the network only has to fill in when we have a number of dull, still days. The US equivalent is probably hot days where everyone turns up the airconditioning.
It is not because (a) our lines are overhead, or (b) our corner of the village is particularly greedy, or (c) that the power company does not have to pay when services are disconnected. Beware of people suggesting 'obvious solutions' without evidence.
The scanner measures the hemodynamic response function. The brain only sends oxygen-rich blood to the regions of the brain that need it. I guess this restricts power consumption, heat sinking requirements, and so on, a bit like the power limiting circuits on a processor. It is likely that the power regulation is a lot less fine grained in the brain than the thinking process itself. So if you had two separate regions that were fed by a single blood supply, you would not be able to distinguish them. In practice, I expect the processing regions and the blood supply regions have fuzzy borders, and there is a limiting return in micro-managing the blood supply.
I do not understand the gas station analogy. To me, this is more like trying to tell how many people are in a building by how many lights are on. You can subtract the permanently on lights from stairwells and corridors. You can then assume a light that goes on, and goes off may be a single person, or a meeting, or a group of people who all come and go at different times. Subtract the lights that are permanently on, and you would expect the person could to be at least the remaining light count, because several people may use the same light.
I gave my mum (95) an old PowerPC laptop I got for the price of buying a replacement power supply. It is running a version of OS that probably is no longer updated, but turning off automatic updates doesn't hurt.. I have also stuck on an Applesript that e-mails me when the machine powers up, which she does every morning to let me know she is OK. She is probably a bit less click-happy then your users.
A 70% prediction rate is not impressive. In the UK, where the weather seems pretty unpredictable, "it will be pretty much the same as yesterday" is right about 70% of the time. Weather forecasting and track individual storms, but It took a long time and a lot of research for the weather forecast success flat rate to get any better than this. The model may be important: the success rate probably isn't.
The article is fine except for this mad bit of hype...
"Now a team of animal behavior specialists have discovered that the social lives of cattle are more complex than biologists had ever imagined..."
This last bit is clearly quite silly: they could imagine that cattle had complex social lives, because they designed an experiment to try and measure the social groupings. They seem to have done a number of sensible things, such as attempting to remove events where cow #1 was close to cow #2 because they were both going for food, or one had to get past the other anyway, or things like that.
Researches reveal amazing facts about cows! The paper that Farmers don't want you to read! Identify cattle with this one weird old tip! You will not believe what cows do when you are not looking!
This is a story about the speed of light being not what we thought it was, and involving general relativity, neutrinos, and its one data point from a unique astronomical event. Oh, yeaah, riiight. And yet, it is clearly explained, and stands a good chance of being right. I am definitely going to have my weird-o-meter recalibrated.
The speed of light is the same as it always was. Any given photon may, extremely rarely, split into an electron-positron pair, and then recombine. The electron and the positron are not travelling at the speed of light, so this event will stick in a small delay. If you measure the speed of light over most human experimental lengths, this event will be very rare - so the very occasional photon will show a tiny delay. If your light travels over such vast distances that the photon may have experienced so many of these delays that it spent whole hours as electrons and positrons.
Each photon will have a random number of these delay events, so you might expect the light pulse to get blurred out a bit by this randomness. There will be a slight blurring, but because the number of events is so huge, the fractional deviation from the mean is pretty tiny.
Cute, and neat. Some posters still try and argue for gravitational viscosity, or for faster-than-light neutrinos, or that this is a failure of science and only philosophers can help us now. Ho-hum. Too little fog, too late, chaps. Better luck with the next one, eh?
The 'OWL' was the first telescope in this series of names as far as I know. I think all the others since have been given 'OWL' like names.
It's a bit unfair to say the 'OWL' project was cancelled because it was really only a feasibility study, and back in the 1980's rather a bonkers one at that. When people started working with computer-controlled segmented mirrors, it because clear that you could make a huge mirror from almost flat segments of glass. So the next step was to see whether you could make a moving and pointing telescope the size of the Great Pyramid. Over they years that 'OWL' wasn't built, the design was improved and it became clear that it was practical to make telescopes between 20m and 100m. Much bigger than 100m, and you probably have to go into space, to avoid the problems of weight, and atmosphere.
One day they may build the 'OWL' on the Antarctica dome, and you will have the finest seeing of all earth-bound telescopes, ever, and there is no point building any others unless you want to look North. The 'ELT' is a nice compromise: it's in Chile and not down by the South Pole which can be as hard to get to as space, and it's bloody big but it leaves something for our kids to do. Yay.
Empty space isn't that empty. You can get virtual pairs of electrons and positrons appearing and disappearing. They pop into existence because they can, even in empty space, but the have negative energy and a virtual wavelength, so they are almost bound to re-coalesce, and the energy of their recombination will exactly equal the energy of their creation, so they pay back all the energy they 'borrowed' and disappear without trace. However, if a photon turns up at this critical moment and pumps in the energy, then they can get permanently separated. Needless to say, this is pretty rare for single photons or we would not be able to see distant galaxies. We need monster photon energy densities, hence the hohlraum (I used to work on these ages ago).
You can also measure a tiny force between two plates in a vacuum due to these virtual particles. This is called the Casmir effect or the Casmir-Polder force. See...
http://en.wikipedia.org/wiki/C... for example. So they are real. Well, real-ish.
This is not the same as Compton scattering. That also makes electron-positron pairs from photons but it also requires some mass to be around. This is the dominant absorbtion mode above about 1.5 MeV. So, I can see how they might get a tiny bit of straight pair production in their hohlraum, but they will also have some high-Z gold plasma giving you lots of conventional Compton scattering, which will look pretty similar. I guess they have a plan for that.
There are 'Garden of Eden' patterns in Conway's game of life. These are patterns that could have no previous generation. Not sure what that does to your parable, though.
This actually looks good to me. Most helicopters can be shot down with a rifle. They are huge engines with large fuel tanks and large, whirling blades, and it is not that difficult to get them to destroy themselves with their own momentum, height, or fuel. This thing has eight separate lifting units. I would imagine with the large body, it would not fall that fast, and even if you were missing several rotors it could land in a controlled fashion. The wheels make it look a bit like the chariot from "Lost In Space" but I imagine it could run over uneven ground with computers anticipating the uneven terrain.
I doubt if it is a fast or as powerful as a purpose designed helicopter. However, for something like mountain rescue it would work. You could drive most of the way with lots of first-aid kit, hop over the river where the bridge is down, get to where you are going, dump the supplies to lose weight, fly up the mountain to rescue people, then drive back fully loaded with everyone on board.
Lastly, if you have to use this in a warlike manner, this is a potential solution. You can use bombs, and drones and gas and napalm to clear the ground, but all skirmishes from the bronze age to today are still settled in the field by one lot of people with weapons going over to another lot of people with weapons on foot, and persuading them to give up. The art has always been to deliver your foot soldiers, fresh and well-equipped, in a short hop to the forward position, and get them back if things go bad. This may do it more safely or more cost-effectively than a helicopter if you avoid the temptation to turn it into a long-distance speed-flying helicopter gunship with frickin' lasers () and just stick to the job in hand. This particular beast may look a bit Jules Verne's Armada of the Skies, and it may turn out to be a dog, but IMHO the thinking behind it is sound.
I went to the presentation at the Royal Society last week given by this group on Grosseteste's colour theory. Grossteste's papers are very dense and very short, and this one fitted on a sheet of A4. He had a theory about colour that seems to have three clear axes and eight corners. However, he never tells us what the axes are called, or names a single colour, or even tells us where white and black come, which the presenters admitted was 'pretty strange'. There is no obvious algebra, which is correct for the age, but makes it very hard to interpret an unambiguous meaning. Aristotle's theory on colour, which Grossteste would have read in translation from Arabic at the time, has clear experimental models for generating infinitesimal shades between any two colours, and names seven colours - perhaps in an early attempt to see how many colours are needed to mix any colour. In contrast, it is difficult to be sure whether Grosseteste's work is philosophical (which colours should exist), experimental (which colours do exist), or mathematical (how can we model what we see).
Grosseteste was known to be one of the better mathematicians of his age. He is not Nostradamus, pumping out cryptic statements in the hopes that some of them will match something at random. What he said was respected in his day. We have some modern computer model that seems to match what he said to some extent, but only for some small subset of the parameter space. I suspect this tells us more about how we think then about how Grossteste did.
Experiments are real but the results aren't pretty. SUSY is pretty but the results aren't real.
When we look at the tables of known particles, it is tempting to think of the periodic table. We might hope to see patterns in the particles, and then guess at the missing parts of the grid. Unfortunately, we don't have nice families of halogens, alkaline earths, and so on. We started off with electrons, protons, and neutrons which all had sensible masses even if the electron was less than a thousandth of the mass of the others, and photons which had no rest mass at all. Then we have a very irregular family of subatomic particles including things like mesons, and neutrinos, with finite but stupidly tiny mass. They don't seem to form a family at all, but a lot of clever people invented new sub-particles called quarks, and in the end managed to come up with a plausible theory that seemed to fit a lot of these weirder particles into families. But not everything.
The periodic table was backed up by quantum calculations, which showed why the should be two elements per row, then eight, and then all the transition elements. Unfortunately, we don't seem to be able to finish off the table of the subatomic elements in the same way. We can come up with neat SUSY theories that would work if there are lots of symmetric particles that we do not ordinarily see, but might be more common at higher energies, and bend the various graphs into fitting at some point. However, as the guy neatly tabulated, all plausible versions of the SUSY theory seem to come up with things that we ought to be able to see with the LHC and other things, and we don't. So, right now, and after a lot of people had spent most of their lives fooling with this model, it is beginning to look like we may have gone down a dead end.
So far we have had 100% negative comments in the direct replies, unless one slips past me while writing this. Many of these raise issues that were raised in the original article. Many others just say it won't be safe if computers are in charge. I am not convinced by any of these.
The Rolls-Royce calculations show that there is a measurable saving in pollution by leaving off most of the crew support features. Fine - a potential saving exists. Now let's explore whether the saving is practical
Large ships do not turn suddenly - it can take miles and tens of minutes to turn a large tanker. You do not have to provide the captain with a real-time 360-degree virtual environment. You have to provide some sort of autonomous fail-safe in case communications are lost. You can have a one-time pad encryption for sending instructions, so remote hacking without a copy of the pad should be difficult if not impossible.
What if the ship gets into difficulties? We know the problems that conventional ships get into. It should be possible to calculate what fraction of these could be fixed by the crew at see, and factored into the potential saving. This is what the analysis should do. If you are in a storm, and a conventional container ship starts spilling its load, there is probably not much the crew can do other than hang on and wait for the storm to pass. It seems entirely reasonable to me that a small number of faults at sea could be fixed by flying out personnel to the ship and landing on the flat top of the containers, if nowhere else. So, you factor in the costs of a call-out.
Might work. Won't ever work if no-one's prepared to think about it, though.
Going to make that point myself. There is 'four score' in English, and an old Northumbrian counting scheme that used to count in multiples of 20 ('chiggit'). Weirdly enough, 'quatre vingts' seems a compartively recent invention: I am told 'ottante' was used in Belgium around WW1. This counting style may not have been ancient.
The UK laws granted a sole case of perpetual rights to 'Peter Pan', which J.M.Barrie had given to the Great Ormond Children's hospital. This isn't quite copyright that 'never grows up' ( see http://www.gosh.org/gen/peterpan/copyright/faq ), but it comes pretty close. I think the UK legislation could be a bit flexible to a time traveller too.
This is happening in a non-linear medium where photons interact: it can't happen in free air. Photons hardly interact on most transparent media, but there are materials with non-linear electric properties that can be used to generate harmonics ( see for example http://en.wikipedia.org/wiki/Second-harmonic_generation ). This is used to convert red light into green in some green laser light pointers. At high power levels, the refractive index increases in more normal materials, which is a nuisance in high-power lasers as light in NdYg glass laser elements can self-focus and damaage the apparatus if the power gets too great.
Hardly "contrary to decades of accepted wisdom about the nature of light" if you can find it in a green laser pointer. Meh.
I do not think the original article was a success for various reasons. It is not easy to explain quantum mechanics convincingly, and I don't think the lack of equations was a main weakness. Those of us who are happy with equations with Hamiltonian operators and eigensolutions probably understand the uncertainty principle too. Those of us who have not touched serious maths, or have done it too long ago will be made to feel stupid rather than being helped.
I think what the article needs was good pictures. How about...
A picture of the Young's slit experiment. A light wave goes through two slits, and interferes with itself. You get fringe patterns. You can calculate the fringe patterns using classical physics.
A picture of the Stern-Gerlach experiment. An electron beam is split into two and interferes with itself. You get similar fringe patterns. What, what? This works with electrons? Yes, it even works with substantial molecules such as buckyballs. In fact, if you did your Young's Slit experiment with a very dim light source and a long integration time, you would be passing photons, one at a time, through the apparatus.
So, when a particle interferes with itself, does it go through the left slit or the right one? Some people say it goes through both, but it doesn't, really. The wave function, which we can calculate but we can't measure, may go through both slits in some senses, and determine the fringe pattern. If we install a detector that can tell us the electron is going through the left slit, or going through the right slit, then the electron goes through one slit, and we do not get the interference pattern. We can know which slit the electron goes through, or we can predict the interference pattern, but we can't do both.
A picture of a wave packet plotted in ordinary space, and in frequency space.
There is nothing magical about the observation, itself. The idea that being observed changes the states dates back to an old and rather unhelpful thing called the Copenhagen model. A better approach is to say that we can measure some property of a particle wavefunction such as the position, or the momentum of the particle; but in measuring the position we lose the ability to also measure the momentum, and vice-versa. In this case, the width of the wave packet determines how accurately we know where the particle is at the time of measurement, while the width in frequency space determines how accurately we know the momentum. Our measurement will tell us what the wavefunction was like at the point of the experiment, but nothing else. This is one form of the Uncertainty principle, but it can be applied to other measurements too.
See, it can be done.
If you don't get it, don't worry: small things and quantum stuff are pretty weird.
Slashdot Mirror
You don't just want a circular object. You want a series of circular rings at the right intervals to interfere and give an intensity peak where the camera is. This s not as efficient as using a giant mirror, but it could be a lot lighter, and less sensitive to vibrations or distortions out of the plane of the disc. Saturn has a lot of rings. The shepherd satellites within the rings make some pretty complex patterns. It may be possible to use the natural structures. Or maybe we could add a few small moons of our own. The camera would have to lie above or below Saturn to look at the unlit side of the rings.
http://en.wikipedia.org/wiki/S...
Yes, this is how science works. It is obvious that talking will help people make flint tools. We all know that. But how do we know that? Saying 'it's obvious' is not helpful. It is also obvious that you can get better at making tools when you can watch someone who is good at it. But you can get plenty of people how have never chipped flint tools, and see how much better they are when they watch someone, when they mutely interact with someone, and when they talk. Some gifted people can pick up musical instruments just by watching, but making flint tools seems to be helped a lot by language.
The article also says that this is suggestive, but could not be considered a proof. They know they have not got ancient people to experiment on. It is not practical to try the same tests with a mammoth hunt. It's not a time machine, but we use what we have.
Then you get a +5 'insightful' mark-up for jeering at it.
It's a high energy plasma out there, how will you get any structure in that?
Actually, the sun has a lot of structure in its magnetic field. This is not just complex in the way Earth's weather is, meaning is is unpredictable. It has long term structures, such as the 11-year sunspot cycle.
I really doubt if these magnetic fields are sentient at all, and certainly not sentient as we understand it. The world's phone system has a similar complexity to the human brain, but if that was sentient, it would be hard to imagine what it thought about, as it has no obvious eyes and ears.
However, suppose we wanted to delay the supernova of our sun. We could do this if we had the technology by injecting fusible hydrogen from the sun's surface into the core at the same rates that it was consumed. This would require completely bonkers apparatus, but the physics is good. Supposing the best and most efficient way of doing this was to influence the magnetic field of the sun so that it did this itself. Suppose the best way of doing that was to artificially induce intelligence in these plasma fields, so it could do this without regulation...
That is a lot of supposes. But in my mind, I think if civilization lasts for astronomical time-scales, this is less ridiculous then expecting to detect them by their leaked unfocussed long-period radio waves, which is what SETI is looking for. I wouldn't spend any money on it, but the thinking doesn't hurt.
Remember 1/object_distance + 1/image_distance = 1/focal_length ?
If you have your screen at R meters away, add (1/R) to your lens strength in diopters. Diopters are 1.0/focal_length in meters. That will give you the same comfortable image_distance at your eye when looking at your screen.
Suppose you have your monitor 0.5 of a meter away, and you use -5.0 diopter glasses because you are short-sighted. You add (1/0.5) = 2.0 to -5.0 diopters and get -3.0 diopters. The person who had -5.0 diopters and used -3.5 diopter lenses for computing work probably uses a screen 2/3 meters away. If you are short-sighted, the diopter values should get smaller in magnitude; if you are long-sighted, the diopter value will get bigger.
Add 2 diopters if your screen is 50 cm away.
Add 1.5 if your screen is 67 cm away.
Add 1 if your screen is 1m away (a bit far, but maybe you have a big monitor)
Hot damn, that school physics is actually good for something! Too bad they had to black out the lab to show us, and we all fell asleep. Now, all I need is some frictionless pulleys and massless string...
Bird strikes can be dangerous if one goes into the engine. This rarely downs an aircraft unless you have a two-engined aircraft and both engines get hit at the same time. Remember the plane that landed in the Hudson after a double bird strike? That was an Airbus A320.
Whether this is a significant risk depends on what the drone flyer is trying to do. If they are trying to get close-up pictures of aircraft then they are probably no bigger risk than birds. If they are aiming for the engines because they want to take down an aircraft, then there is a significant risk, particularly of the drone is carrying some load designed to do damage. Why would someone do this? I dunno. Why do people use laser pointers to try and blind pilots? Maybe not terrorism: some people are just dicks.
What do we do? Well, if they are radio-controlled then we can pinpoint the controller by radio. It would be a nice problem to design a set of drones that can triangulate the source of a radio signal, home in on it, and track what they find.
The actual article is a bit shallow on detail, but here's my interpolation...
Infra-red is quite a broad bit of the spectrum. It starts at about 800nm as light we can't quite see, and security cameras use this band with an infra-red illuminant. If we go down to about 2000nm, we are into the mid-band where some IR cameras operate. These can see hot objects but cannot people by their radiated body heat. There is a gap at about 3500nm where water vapour absorbs and emits, and cameras do not work well. Then there is another band at about 7000nm where the thermal cameras that can pick up body heat work. The cooler you are, the greater fraction of long wavelength you emit. (NB: if the exact wavelengths are important, please check as I am typing this off the top of my head).
Most black paints absorb all infra-red wavelengths equally. Some white paints will absorb the far-infra-red. What you want, and what I think they have done is to make somethng that reflects down to 2000nm, and then absorbs beyond about 400nm. This will reflect a lot of the heat from the sun, but will still radiate the heat from the building.
Does it work? Will it still work when it is dirty? I don't know, but at least it does not violate any thermodynamic principles.
I live in a large village or small town. I get a lot of power outages. Some of these last for hours. Most of the rest of the village does not get these - just a small clump of houses around the church. Our cable comes underground from Hemel Hempstead. The rest of the village gets power from the pylons that run alongside the M1. We can claim back money for the power outages.
I would imagine our group of houses has problems because (a) we are at the end of a spur (b) we got electricity before anyone else, and before the M1 was built, so our lines are particularly old, and (c) the power distribution network has probably shifted, and our little bit has not been altered to reflect the changes. If you live out in the sticks, you become more vulnerable: I remember a house where the power used to trip out when the transport cafe about a mile away turned off their grills last thing at night. One of the downsides of generating your own power may be that the network only has to fill in when we have a number of dull, still days. The US equivalent is probably hot days where everyone turns up the airconditioning.
It is not because (a) our lines are overhead, or (b) our corner of the village is particularly greedy, or (c) that the power company does not have to pay when services are disconnected. Beware of people suggesting 'obvious solutions' without evidence.
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The scanner measures the hemodynamic response function. The brain only sends oxygen-rich blood to the regions of the brain that need it. I guess this restricts power consumption, heat sinking requirements, and so on, a bit like the power limiting circuits on a processor. It is likely that the power regulation is a lot less fine grained in the brain than the thinking process itself. So if you had two separate regions that were fed by a single blood supply, you would not be able to distinguish them. In practice, I expect the processing regions and the blood supply regions have fuzzy borders, and there is a limiting return in micro-managing the blood supply.
I do not understand the gas station analogy. To me, this is more like trying to tell how many people are in a building by how many lights are on. You can subtract the permanently on lights from stairwells and corridors. You can then assume a light that goes on, and goes off may be a single person, or a meeting, or a group of people who all come and go at different times. Subtract the lights that are permanently on, and you would expect the person could to be at least the remaining light count, because several people may use the same light.
Hey, it's a start.
I gave my mum (95) an old PowerPC laptop I got for the price of buying a replacement power supply. It is running a version of OS that probably is no longer updated, but turning off automatic updates doesn't hurt.. I have also stuck on an Applesript that e-mails me when the machine powers up, which she does every morning to let me know she is OK. She is probably a bit less click-happy then your users.
A 70% prediction rate is not impressive. In the UK, where the weather seems pretty unpredictable, "it will be pretty much the same as yesterday" is right about 70% of the time. Weather forecasting and track individual storms, but It took a long time and a lot of research for the weather forecast success flat rate to get any better than this. The model may be important: the success rate probably isn't.
The article is fine except for this mad bit of hype...
"Now a team of animal behavior specialists have discovered that the social lives of cattle are more complex than biologists had ever imagined..."
This last bit is clearly quite silly: they could imagine that cattle had complex social lives, because they designed an experiment to try and measure the social groupings. They seem to have done a number of sensible things, such as attempting to remove events where cow #1 was close to cow #2 because they were both going for food, or one had to get past the other anyway, or things like that.
Researches reveal amazing facts about cows! The paper that Farmers don't want you to read! Identify cattle with this one weird old tip! You will not believe what cows do when you are not looking!
It could be worse, I guess...
This is a story about the speed of light being not what we thought it was, and involving general relativity, neutrinos, and its one data point from a unique astronomical event. Oh, yeaah, riiight. And yet, it is clearly explained, and stands a good chance of being right. I am definitely going to have my weird-o-meter recalibrated.
The speed of light is the same as it always was. Any given photon may, extremely rarely, split into an electron-positron pair, and then recombine. The electron and the positron are not travelling at the speed of light, so this event will stick in a small delay. If you measure the speed of light over most human experimental lengths, this event will be very rare - so the very occasional photon will show a tiny delay. If your light travels over such vast distances that the photon may have experienced so many of these delays that it spent whole hours as electrons and positrons.
Each photon will have a random number of these delay events, so you might expect the light pulse to get blurred out a bit by this randomness. There will be a slight blurring, but because the number of events is so huge, the fractional deviation from the mean is pretty tiny.
Cute, and neat. Some posters still try and argue for gravitational viscosity, or for faster-than-light neutrinos, or that this is a failure of science and only philosophers can help us now. Ho-hum. Too little fog, too late, chaps. Better luck with the next one, eh?
The 'OWL' was the first telescope in this series of names as far as I know. I think all the others since have been given 'OWL' like names.
It's a bit unfair to say the 'OWL' project was cancelled because it was really only a feasibility study, and back in the 1980's rather a bonkers one at that. When people started working with computer-controlled segmented mirrors, it because clear that you could make a huge mirror from almost flat segments of glass. So the next step was to see whether you could make a moving and pointing telescope the size of the Great Pyramid. Over they years that 'OWL' wasn't built, the design was improved and it became clear that it was practical to make telescopes between 20m and 100m. Much bigger than 100m, and you probably have to go into space, to avoid the problems of weight, and atmosphere.
One day they may build the 'OWL' on the Antarctica dome, and you will have the finest seeing of all earth-bound telescopes, ever, and there is no point building any others unless you want to look North. The 'ELT' is a nice compromise: it's in Chile and not down by the South Pole which can be as hard to get to as space, and it's bloody big but it leaves something for our kids to do. Yay.
Empty space isn't that empty. You can get virtual pairs of electrons and positrons appearing and disappearing. They pop into existence because they can, even in empty space, but the have negative energy and a virtual wavelength, so they are almost bound to re-coalesce, and the energy of their recombination will exactly equal the energy of their creation, so they pay back all the energy they 'borrowed' and disappear without trace. However, if a photon turns up at this critical moment and pumps in the energy, then they can get permanently separated. Needless to say, this is pretty rare for single photons or we would not be able to see distant galaxies. We need monster photon energy densities, hence the hohlraum (I used to work on these ages ago).
You can also measure a tiny force between two plates in a vacuum due to these virtual particles. This is called the Casmir effect or the Casmir-Polder force. See... http://en.wikipedia.org/wiki/C... for example. So they are real. Well, real-ish.
This is not the same as Compton scattering. That also makes electron-positron pairs from photons but it also requires some mass to be around. This is the dominant absorbtion mode above about 1.5 MeV. So, I can see how they might get a tiny bit of straight pair production in their hohlraum, but they will also have some high-Z gold plasma giving you lots of conventional Compton scattering, which will look pretty similar. I guess they have a plan for that.
Here's a fun site... http://profmattstrassler.com/a...
There are 'Garden of Eden' patterns in Conway's game of life. These are patterns that could have no previous generation. Not sure what that does to your parable, though.
This actually looks good to me. Most helicopters can be shot down with a rifle. They are huge engines with large fuel tanks and large, whirling blades, and it is not that difficult to get them to destroy themselves with their own momentum, height, or fuel. This thing has eight separate lifting units. I would imagine with the large body, it would not fall that fast, and even if you were missing several rotors it could land in a controlled fashion. The wheels make it look a bit like the chariot from "Lost In Space" but I imagine it could run over uneven ground with computers anticipating the uneven terrain.
I doubt if it is a fast or as powerful as a purpose designed helicopter. However, for something like mountain rescue it would work. You could drive most of the way with lots of first-aid kit, hop over the river where the bridge is down, get to where you are going, dump the supplies to lose weight, fly up the mountain to rescue people, then drive back fully loaded with everyone on board.
Lastly, if you have to use this in a warlike manner, this is a potential solution. You can use bombs, and drones and gas and napalm to clear the ground, but all skirmishes from the bronze age to today are still settled in the field by one lot of people with weapons going over to another lot of people with weapons on foot, and persuading them to give up. The art has always been to deliver your foot soldiers, fresh and well-equipped, in a short hop to the forward position, and get them back if things go bad. This may do it more safely or more cost-effectively than a helicopter if you avoid the temptation to turn it into a long-distance speed-flying helicopter gunship with frickin' lasers () and just stick to the job in hand. This particular beast may look a bit Jules Verne's Armada of the Skies, and it may turn out to be a dog, but IMHO the thinking behind it is sound.
I went to the presentation at the Royal Society last week given by this group on Grosseteste's colour theory. Grossteste's papers are very dense and very short, and this one fitted on a sheet of A4. He had a theory about colour that seems to have three clear axes and eight corners. However, he never tells us what the axes are called, or names a single colour, or even tells us where white and black come, which the presenters admitted was 'pretty strange'. There is no obvious algebra, which is correct for the age, but makes it very hard to interpret an unambiguous meaning. Aristotle's theory on colour, which Grossteste would have read in translation from Arabic at the time, has clear experimental models for generating infinitesimal shades between any two colours, and names seven colours - perhaps in an early attempt to see how many colours are needed to mix any colour. In contrast, it is difficult to be sure whether Grosseteste's work is philosophical (which colours should exist), experimental (which colours do exist), or mathematical (how can we model what we see).
Grosseteste was known to be one of the better mathematicians of his age. He is not Nostradamus, pumping out cryptic statements in the hopes that some of them will match something at random. What he said was respected in his day. We have some modern computer model that seems to match what he said to some extent, but only for some small subset of the parameter space. I suspect this tells us more about how we think then about how Grossteste did.
Naah. They didn't do that back then. Anyhow, he was Bishop of Lincoln, so he would probably be in charge of the people with matches.
Experiments are real but the results aren't pretty. SUSY is pretty but the results aren't real.
When we look at the tables of known particles, it is tempting to think of the periodic table. We might hope to see patterns in the particles, and then guess at the missing parts of the grid. Unfortunately, we don't have nice families of halogens, alkaline earths, and so on. We started off with electrons, protons, and neutrons which all had sensible masses even if the electron was less than a thousandth of the mass of the others, and photons which had no rest mass at all. Then we have a very irregular family of subatomic particles including things like mesons, and neutrinos, with finite but stupidly tiny mass. They don't seem to form a family at all, but a lot of clever people invented new sub-particles called quarks, and in the end managed to come up with a plausible theory that seemed to fit a lot of these weirder particles into families. But not everything.
The periodic table was backed up by quantum calculations, which showed why the should be two elements per row, then eight, and then all the transition elements. Unfortunately, we don't seem to be able to finish off the table of the subatomic elements in the same way. We can come up with neat SUSY theories that would work if there are lots of symmetric particles that we do not ordinarily see, but might be more common at higher energies, and bend the various graphs into fitting at some point. However, as the guy neatly tabulated, all plausible versions of the SUSY theory seem to come up with things that we ought to be able to see with the LHC and other things, and we don't. So, right now, and after a lot of people had spent most of their lives fooling with this model, it is beginning to look like we may have gone down a dead end.
The Rolls-Royce calculations show that there is a measurable saving in pollution by leaving off most of the crew support features. Fine - a potential saving exists. Now let's explore whether the saving is practical
Large ships do not turn suddenly - it can take miles and tens of minutes to turn a large tanker. You do not have to provide the captain with a real-time 360-degree virtual environment. You have to provide some sort of autonomous fail-safe in case communications are lost. You can have a one-time pad encryption for sending instructions, so remote hacking without a copy of the pad should be difficult if not impossible.
What if the ship gets into difficulties? We know the problems that conventional ships get into. It should be possible to calculate what fraction of these could be fixed by the crew at see, and factored into the potential saving. This is what the analysis should do. If you are in a storm, and a conventional container ship starts spilling its load, there is probably not much the crew can do other than hang on and wait for the storm to pass. It seems entirely reasonable to me that a small number of faults at sea could be fixed by flying out personnel to the ship and landing on the flat top of the containers, if nowhere else. So, you factor in the costs of a call-out.
Might work. Won't ever work if no-one's prepared to think about it, though.
Going to make that point myself. There is 'four score' in English, and an old Northumbrian counting scheme that used to count in multiples of 20 ('chiggit'). Weirdly enough, 'quatre vingts' seems a compartively recent invention: I am told 'ottante' was used in Belgium around WW1. This counting style may not have been ancient.
The UK laws granted a sole case of perpetual rights to 'Peter Pan', which J.M.Barrie had given to the Great Ormond Children's hospital. This isn't quite copyright that 'never grows up' ( see http://www.gosh.org/gen/peterpan/copyright/faq ), but it comes pretty close. I think the UK legislation could be a bit flexible to a time traveller too.
This is happening in a non-linear medium where photons interact: it can't happen in free air. Photons hardly interact on most transparent media, but there are materials with non-linear electric properties that can be used to generate harmonics ( see for example http://en.wikipedia.org/wiki/Second-harmonic_generation ). This is used to convert red light into green in some green laser light pointers. At high power levels, the refractive index increases in more normal materials, which is a nuisance in high-power lasers as light in NdYg glass laser elements can self-focus and damaage the apparatus if the power gets too great.
Hardly "contrary to decades of accepted wisdom about the nature of light" if you can find it in a green laser pointer. Meh.
I do not think the original article was a success for various reasons. It is not easy to explain quantum mechanics convincingly, and I don't think the lack of equations was a main weakness. Those of us who are happy with equations with Hamiltonian operators and eigensolutions probably understand the uncertainty principle too. Those of us who have not touched serious maths, or have done it too long ago will be made to feel stupid rather than being helped.
I think what the article needs was good pictures. How about...
A picture of the Young's slit experiment. A light wave goes through two slits, and interferes with itself. You get fringe patterns. You can calculate the fringe patterns using classical physics.
A picture of the Stern-Gerlach experiment. An electron beam is split into two and interferes with itself. You get similar fringe patterns. What, what? This works with electrons? Yes, it even works with substantial molecules such as buckyballs. In fact, if you did your Young's Slit experiment with a very dim light source and a long integration time, you would be passing photons, one at a time, through the apparatus.
So, when a particle interferes with itself, does it go through the left slit or the right one? Some people say it goes through both, but it doesn't, really. The wave function, which we can calculate but we can't measure, may go through both slits in some senses, and determine the fringe pattern. If we install a detector that can tell us the electron is going through the left slit, or going through the right slit, then the electron goes through one slit, and we do not get the interference pattern. We can know which slit the electron goes through, or we can predict the interference pattern, but we can't do both.
A picture of a wave packet plotted in ordinary space, and in frequency space.
There is nothing magical about the observation, itself. The idea that being observed changes the states dates back to an old and rather unhelpful thing called the Copenhagen model. A better approach is to say that we can measure some property of a particle wavefunction such as the position, or the momentum of the particle; but in measuring the position we lose the ability to also measure the momentum, and vice-versa. In this case, the width of the wave packet determines how accurately we know where the particle is at the time of measurement, while the width in frequency space determines how accurately we know the momentum. Our measurement will tell us what the wavefunction was like at the point of the experiment, but nothing else. This is one form of the Uncertainty principle, but it can be applied to other measurements too.
See, it can be done. If you don't get it, don't worry: small things and quantum stuff are pretty weird.