They don't have mass (any zero mass particle travels at the speed of light) but they do have energy (E=mc^2 doesn't work for a photon...)
The photon energy is taken into account, but it's currently a tiny fraction of the total energy (most of which is dark energy, the rest mostly dark matter - which does obey E=mc^2). If i recall corrrectly, currently the photons (namely the cosmic microwave background) contribute 0.004 of the total energy (starlight probably contributes less, but I could be wrong). In the past, however, photons dominated the energy (photons cooled over time due to redshifting, so they were very hot and energetic in the past).
Because according to general relativity our universe is a 4-dimensional Riemannian manifold called spacetime, which has curvature like any other Riemannian manifold. The shape of this curved 4d sheet is determined by the mass and energy that sits on it. The equations show that generically the shape you get for the type of mass and energy we observe in our universe is one where the space dimensions expand or contract along the time dimension. I don't think even hardcore theoretical physicists have a more intuitive understanding than that, but any hardcore physicists feel free to step in and offer one.
Bear in mind the pressure that dark energy exerts is actually *negative*. So this "stuff" is not just some ordinary invisible stuff filling space that happens to be invisible (that would be dark matter), it's much weirder.
Incidentally, the photon spins along its axis of motion (either forward or backward). These are sometimes called helicity states. Whereas the polarization of a classical EM wave usually means the axis of motion of its electric field, which is orthogonal to the direction of motion.
Polarization of an electromagnetic wave is a classical concept -- individual photons have two possible polarizations, but those are NOT equivalent to the polarization of the EM wave. In an EM wave there are a HUGE number of individual photons.
Experimentally, if I measure one of the photons to be "up" along direction vector N, then the other will be "down" along the same direction vector. These are just ordinary photons. There's no way that could happen without the two photons being connected in some way (unless I pre-arrange it, but this works for any direction vector N. You can't pre-arrange that, at least not via classical physics). In quantum mechanics that happens because the two photons do not exist independently, their properties are measured by probing disturbing the entire system which is described as a superposition of photon states (some mathematics is needed to understand this properly, of course). I recommend Feynman's Lectures Vol III for an extremely clear and logical explanation for why quantum mechanics and the "spooky action at a distance" is needed.
As a lifelong science fiction aficionado, I have to tell you that Serenity is about as significant as the average episode of Star Trek. The plot is childish and just doesn't make much sense except in a "well it's only a movie who cares about realism" way. It's just about cute chicks, unconvincing faux-toughness, a mindset where simply saying "planets are terraformed, a process taking decades" and never mentioning it again somehow evokes a rich world, a cluelessness such that the zombie ships parked in some small region are supposed to block entrance to an entire planet, and endless inane "zingy" one-liners (zingy if you're a big Buffy fan I guess). But I realize you are a fan and no amount of logic and perspective will cure your affliction.
Nowadays they can use OpenGL, and instead of drawing circles with Bresenham for about the same amount of research effort they can make 3d volumetric models with per pixel shading. I wish OpenGL (and lots of other great open source libraries) had existed when I was a kid.
I hate the way they felt the need to throw in a "small" there. What, is that supposed to automatically imply nerdy or weird or something? They might as well go the whole hog and say "small, ugly, socially inept male losers" just to really emphasize the contrast with the new wave of women "sci fi" fans (I suspect saying "small women who sit in dark rooms" would not be acceptable).
There a lot's of ideas about how life might have begun but not much concrete evidence as yet. The most promising idea is that life began as replicating strands of RNA encased in lipid membranes, which is not too dissimilar from what these guys are trying. Except in the RNA case, it took many hundreds of millions of years of random chemical interactions in the prebiotic ocean for the right RNA configurations with suitable inorganic catalysts to appear. It was undoubtedly a very improbable event that kickstarted life on earth, but it only had to happen once and the number of possible starting points was enormous, outweighing the improbability of the event (it is hypothesized). Once a stable replicator was present in the ocean, natural selection began to operate and led inevitably to the tree of life.
You're probably right that a sawing motion is not practical in an attack. But more generally, I'm not sure exactly why it is useful to build a robot arm to do their demonstration. Wouldn't a few minutes experimentation with a sharp piece of bone and a lump of meat achieve the same, and probably give you more insight about the specific types of movement you can use to cause damage than just manipulating this simplistic arm? I suspect they used the arm to lend some extra perceived scientific flavor to their observations. It's an experiment with a *robot*, so it must be right.
It seems possible their methodology and conclusions are flawed. If you saw away at a large chunk of meat with a small but sharp knife you can make a deep wound. Why do they assume the raptor attacks in a short stabbing motion? What about other modes of attack their "robotic arm" doesn't simulate?
Is copyright law the final word when it comes to the definition of "own", or is it possible that the word "own" has other meanings and connotations in other spheres, and actually there isn't a generally agreed upon rigorous definition? I hate lawyer speak. Isn't it futile arguing over the nature of ownership based on some definition dreamt up for convenience by a particular legal system (unless of course we're arguing like lawyers and are only interested in one-upping the other guy within some constraints in order to win a contest).
I would claim there is no such "tiering" rule. It's simply the case that the best and brightest people want to a) be where all the other bright people are, and b) work in a very comfortable and pleasant environment with a ton of prestige attached. So it's not that the Michigan guy is crossed off a list at Harvard because of some rule. He's crossed off because the applicants from Stanford, Yale, MIT, etc. are so incredibly good. And they are good because the best and brightest people in grad school were at Stanford, Yale, etc. because of reasons a), b). etc. etc. It's like an automatic feedback mechanism, a perfect meritocracy.
Why did they embed the video camera inside a big load of brush bristles? To make the kids feel "at ease" with the device? I imagine someone is writing their thesis right now on how important the damn bristles are for making the kids feel at ease. Meanwhile, on the other side of the MIT campus, the grown ups are sequencing the rat genome.
How about a system that lets you paint by pissing on a pressure sensitive digital canvus. The saltier the piss the deeper the color. With virtual ammonia stench too! Wouldn't that be revolutionary, you media lab bastard.
I think what happens is that in order to get the "spread" in the first place, from two given lines, you would have to do some computation with sines or cosines (or something equivalent, probably involving a Taylor expansion).
Of course, if you start with a problem where you are just given the spread, as in his examples, you find you can do everything with rational functions. But in a real problem, you are not going to know the spread. There's a reason sines and cosines appear in geometry. It's because they're quite fundamental functions, e.g. in the theory of complex numbers.
Slashdot Mirror
They don't have mass (any zero mass particle travels at the speed of light) but they do have energy (E=mc^2 doesn't work for a photon...)
The photon energy is taken into account, but it's currently a tiny fraction of the total energy (most of which is dark energy, the rest mostly dark matter - which does obey E=mc^2). If i recall corrrectly, currently the photons (namely the cosmic microwave background) contribute 0.004 of the total energy (starlight probably contributes less, but I could be wrong). In the past, however, photons dominated the energy (photons cooled over time due to redshifting, so they were very hot and energetic in the past).
Because according to general relativity our universe is a 4-dimensional Riemannian manifold called spacetime, which has curvature like any other Riemannian manifold. The shape of this curved 4d sheet is determined by the mass and energy that sits on it. The equations show that generically the shape you get for the type of mass and energy we observe in our universe is one where the space dimensions expand or contract along the time dimension. I don't think even hardcore theoretical physicists have a more intuitive understanding than that, but any hardcore physicists feel free to step in and offer one.
Bear in mind the pressure that dark energy exerts is actually *negative*. So this "stuff" is not just some
ordinary invisible stuff filling space that happens to be invisible (that would be dark matter), it's much weirder.
Incidentally, the photon spins along its axis of motion (either forward or backward). These are sometimes called helicity states. Whereas the polarization of a classical EM wave usually means the axis of motion of its electric field, which is orthogonal to the direction of motion.
Polarization of an electromagnetic wave is a classical concept -- individual photons have two possible polarizations, but those are NOT equivalent to the polarization of the EM wave. In an EM wave there are a HUGE number of individual photons.
Experimentally, if I measure one of the photons to be "up" along direction vector N, then the other will be "down" along the same direction vector. These are just ordinary photons. There's no way that could happen without the two photons being connected in some way (unless I pre-arrange it, but this works for any direction vector N. You can't pre-arrange that, at least not via classical physics).
In quantum mechanics that happens because the two photons do not exist independently, their properties are measured by probing disturbing the entire system which is described as a superposition of photon states (some mathematics is needed to understand this properly, of course).
I recommend Feynman's Lectures Vol III for an extremely clear and logical explanation for why quantum mechanics and the "spooky action at a distance" is needed.
You're drug-free! Congrats! When did you get off it?
In other news, you can't get past that booooring first chapter of The Fellowship of the Ring.
So perhaps Dark City could be considered a space movie.
As a lifelong science fiction aficionado, I have to tell you that Serenity is about as significant as the average
episode of Star Trek. The plot is childish and just doesn't make much sense except in a "well it's only a movie who cares about realism" way. It's just about cute chicks, unconvincing faux-toughness, a mindset where simply saying "planets are terraformed, a process taking decades" and never mentioning it again somehow evokes a rich world, a cluelessness such that the zombie ships parked in some small region are supposed to block entrance to an entire planet, and endless inane "zingy" one-liners (zingy if you're a big Buffy fan I guess). But I realize you are a fan and no amount of logic and perspective will cure your affliction.
wait, John von Neumann was your high school CS teacher. Shiittttt
Nowadays they can use OpenGL, and instead of drawing circles with Bresenham for about the same amount of research effort they can make 3d volumetric models with per pixel shading. I wish OpenGL (and lots of other great open source libraries) had existed when I was a kid.
the root of any number that cannot be stated as n^2 where n is not an integer, do you think they could do it?
Maybe if you cleaned up your grammar so the challenge even makes fucking sense (I guess by cannot you meant can, maybe? I dunno)
I hate the way they felt the need to throw in a "small" there. What, is that supposed to automatically imply nerdy or weird or something? They might as well go the whole hog and say "small, ugly, socially inept male losers" just to really emphasize the contrast with the new wave of women "sci fi" fans (I suspect saying "small women who sit in dark rooms" would not be acceptable).
There a lot's of ideas about how life might have begun but not much concrete evidence as yet.
The most promising idea is that life began as replicating strands of RNA encased in lipid membranes,
which is not too dissimilar from what these guys are trying. Except in the RNA case, it took many hundreds of millions of years of random chemical interactions in the prebiotic ocean for the right RNA configurations with suitable inorganic catalysts to appear. It was undoubtedly a very improbable event that kickstarted life on earth, but it only had to happen once and the number of possible starting points was enormous, outweighing the improbability of the event (it is hypothesized). Once a stable replicator was present in the ocean, natural selection began to operate and led inevitably to the tree of life.
You're probably right that a sawing motion is not practical in an attack. But more generally, I'm not sure exactly why it is useful to build a robot arm to do their demonstration. Wouldn't a few minutes experimentation with a sharp piece of bone and a lump of meat achieve the same, and probably give you more insight about the specific types of movement you can use to cause damage than just manipulating this simplistic arm? I suspect they used the arm to lend some extra perceived scientific flavor to their observations. It's an experiment with a *robot*, so it must be right.
It seems possible their methodology and conclusions are flawed. If you saw away at a large chunk of meat with a small but sharp knife you can make a deep wound. Why do they assume the raptor attacks in a short stabbing motion? What about other modes of attack their "robotic arm" doesn't simulate?
I'm holding out for Ubuntu Luscious Beaver
Is copyright law the final word when it comes to the definition of "own", or is it possible that the word "own" has other
meanings and connotations in other spheres, and actually there isn't a generally agreed upon rigorous definition?
I hate lawyer speak. Isn't it futile arguing over the nature of ownership based on some definition dreamt up for convenience by a particular legal system (unless of course we're arguing like lawyers and are only interested in one-upping the other guy within some constraints in order to win a contest).
think of what they are paying just to have telnet to a main system!
Why should it cost more to do the networking with a Windows system? Just asking
I would claim there is no such "tiering" rule. It's simply the case that the best and brightest people want to
a) be where all the other bright people are, and b) work in a very comfortable and pleasant environment with a ton of prestige attached. So it's not that the Michigan guy is crossed off a list at Harvard because of some rule. He's crossed off because the applicants from Stanford, Yale, MIT, etc. are so incredibly good. And they are good because the best and brightest people in grad school were at Stanford, Yale, etc. because of reasons a), b). etc. etc. It's like an automatic feedback mechanism, a perfect meritocracy.
Why did they embed the video camera inside a big load of brush bristles? To make the kids feel "at ease" with the device? I imagine someone is writing their thesis right now on how important the damn bristles are for making the kids feel at ease. Meanwhile, on the other side of the MIT campus, the grown ups are sequencing the rat genome.
How about a system that lets you paint by pissing on a pressure sensitive digital canvus. The saltier the piss the deeper the color. With virtual ammonia stench too! Wouldn't that be revolutionary, you media lab bastard.
in radians please
that sucks ass
I think what happens is that in order to get the "spread" in the first place, from two given lines, you would have to do some computation with sines or cosines (or something equivalent, probably involving a Taylor expansion).
Of course, if you start with a problem where you are just given the spread, as in his examples, you find you can do everything with rational functions. But in a real problem, you are not going to know the spread. There's a reason sines and cosines appear in geometry. It's because they're quite fundamental functions, e.g. in the theory of complex numbers.