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.
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.
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.
Remember when the Hubble telescope first went up, and could not focus? It had all been tested on the ground on an artificial star target. Unfortunately, the test rig had a plate that was about half-an-inch thick that should have been subtracted from the optical path. So they had a mirror that was accurate to about 1/100th of a wave but half an inch in the wrong place.
There was a rocket where the guidance for the two stages had been coded separately. One stage used a value of -9.8 m/s2 for 'g' because it measured heights upwards and the acceleration was downwards, while the other used a value of +9.8 m/s2 and flipped the sign in the equations. When the rocket took off, the first stage was fine but the second stage suddenly flipped over.
That's what I dread: thinking I have checked everything, and thought of everything, and then finding out publicly and expensively that my regression tests were worthless all along.