For some reason, I think I remember reading that as matter crosses the event horizon, it's stripped apart at the subatomic level (I suppose due to extreme gravitational forces) and that matter is shot inwards (towards the singulatity), while anti-matter is shot outwards away from the singulatiry. Please do correct me if I'm wrong, but I can look up wherever I read that if you'd like.
You're thinking of Hawking Radiation. It has nothing to do with matter falling through a black hole, but rather with virtual particle/antiparticle pairs that are being created and destroyed everywhere in space all the time. Thanks to Hesienberg's Uncertainty Principle, you can violate the conservation of energy if you do it over a very short period of time. All around us, there's a sort of "froth" in the vacuum made of electrons and antielectrons which spontaneously are created and then annihiliated. It all happens so extremely fast that nobody could observe any violation of conservation of energy.
When this happens right on the event horizon of a black hole, however, you can end up with one particle going into the singularity and the other particle escaping. Now, I don't understand the physics of this process in detail! I should-- I ought to look it up. However, what happens is that if the particle/antiparticle pair is created right at the exact spot, it can happen that rather than annihilating each other, they split and turn into real particles. You can observe the particle coming out, and to keep things balanced, the particle going in then has negative energy. The result is that the black hole loses mass (a very tiny amount, mind you). Over time, therefore, black holes evaporate. (Note that many black holes, esp. those at the center of galaxies, are being fed (and thus growing) much faster than they evaporate due to Hawking radiation.)
The timescale for evaporation of any appreciably sized black hole (solar mass on up to these supermassive black holes) is gigantic-- longer than the age of the universe. Very small ones, though, evaporate pretty quicky. Thus, if there were tiny black holes left over (say) from the Big Bang, we wouldn't expect to find any of them around today.
As for matter falling into a black hole: the tidal forces get larger and larger as you get closer to the black hole. Of course, this happens with any mass. Tidal forces due to being too close to the moon cause the Earth to stretch a bit and its water to slosh around. If you fall into a solar mass black hole, however, even before you got to the event horizon, the difference in the gravitational force on your feet and on your head would tear you apart. This will happen with all black holes, and it's an issue whether you're inside or outside the event horizon. Indeed, the event horizon is largely irrelevant to it, except as a limit of inevitability. For very large black holes, the tidal forces aren't so bad at the event horizon that you ought to be able to drop through it. For solar mass black holes, the tidal forces will kill you long before you can get to the event horizon.
If you remember back in 1993 or 1994 when comet Shoemaker-Levy 9 hit Jupiter, it hit in several chunks over the course of several days. The reason was that the comet had been riped apart on a previous pass by Jupiter-- by exactly these same tidal forces. (Comets aren't really held together all that well, as things go, and Jupiter is pretty massive. Tidal forces from Jupiter and the other moons are also what heats up IO and keeps it volcanically active.) My point: tidal forces aren't some mysterious black hole thing, they're something you get with any mass. The only thing about black holes is that you can tend to get a lot closer to that mass than you can with any other form of the smae mass. (E.g., with the Sun, you'd have to be well inside the Sun before the tidal forces got that strong--- but at that point, most of the Sun's mass would be outside your position on the Sun, and therefore you wouldn't be feeling its gravity.)
Yes, time dialation approaches infinity as you approach the event horizon, so you can never actually enter a black hole, only mosey up to it:-)
This statement is commonly made, but it's not really accurate.
Yes, from the point of view of a distant observer, somebody falling into a black hole takes an infinite amount of time to do it. However, in the frame of reference of the hole-diver, the coordinates used for the far observer are no good. In fact, the Physics shows that in his frame of reference, the hole-diver goes through the hole in a finite amount of time, and that indeed nothing particularly startling happens at the moment of crossing the event horizon. (Other than it is after that that he will inevitably hit the singularity; however, there's no grand event that signifies the moment of crossing.)
Sounds contradictory, so you will ask, which is "really" right? I like to think about it with this thought experiment. Given an arbitrary amount of energy (and technology and ability to withstand tidal forces and etc.), could the far observer, after waiting an arbitrary amount of time, go in and retrive the hole-diver? If the hole-diver really does take an infinite amount of time to cross, then the answer would be "yes". It would be hard, but in principle the far observer could get the hole-diver. However, the coordinates that apply near the event horizon make it clear that the answer is "no". There eventually comes a time when an external observer, if he waits to long, is inable to retrieve the hole-diver.
What the far observer sees is the photons emitted by the hole-diver. As the hole-diver gets closer and closer to the black hole, the photons get further and further apart (time dilation) and longer and longer in redshift (gravitational redshift). The "last" photon is infinitely redshifted and takes an infinite amount of time to get out-- so the far observer never measures the hole-diver to drop through the hole.
I wish people would just be a little more careful
in their phrasing, as indeed, black holes themselves are still theories.
Even relativity is only a theory. But I digress.
In fact I'd recommend you be a little more careful with phrasing.... It is a heuristic that when you hear the phrase "only a theory", the person saying it doesn't understand science. I'm not saying that this is the case with you! But your use of that phrase does raise alarm bells.
Lots of things are theories. The theory of gravity, for example. However, just because the theory of gravity is only a theory doesn't mean that a ball won't fall down when I drop it.
Relativity is a theory-- but not "only" a theory. It's a wildly successful theory which has yet to be proven false.
(And note that all scientists still think of Newtonian gravity to be a "correct" theory even though the success of relativity proves it to be "wrong". Newtonian gravity is right because it's the limit of relativity in certain specific cases, i.e. things aren't moving too fast and the gravitational field isn't too intense. In those cases, every test we've made show's that it's right.)
Science can never prove a theory. It can only disprove it. However, when a theory has a long track record of making succesful predictions, we eventually tend to think that it's probably right. Gravity, thermodyanmics, relativity, quantum mechanics, any number of other things are all theories, but that doesn't mean that they're just some wild-eyed speculation that something things "might" be true about the universe. They're all much much more solid than that. Saying something is a "theory" is not at all akin to saying that it is on shaky ground. It merely means that it's the description we use for something in nature, which may be wrong, likely, or on extremely solid ground.
I would bet there are black holes at the center of ALL spiral galaxies like our Milky Way. Other shaped galaxies may just be at earlier stages of evolution (such as elliptical) before their holes have formed.
Another point: yes, and no. Yes, most big galaxies probably have huge black holes at their center. But so do most big elliptical galaxies. Also, it is completely inaccurate to say that elliptical galaxies are "earlier in their evolution" than spirals. Once astronomers thought this, but many decades have gone by since then. Ellipticals do not evolve into spirals. What's more, there is evidence in many cases for hugeass black holes at the center of big ellipticals; M87, a large giant elliptical in the Virgo Cluster, is a good example. Many other examples exist. For instance, radio galaxies and quasars (both evidence of nuclear activity attributable to a supermassive black hole) are often found in elliptical galaxies.
(If anything, the evolution may go the other way: by merging enough sprials, you can end up with something that looks more like an elliptical! However, it would be too simplistic to say that "elliptical galaxies all result from mergers of spirals". They're each their own thing, really, with the caveat that shapes can change when galaxies run into each other.)
I've always thought it was obvious that super-massive blackholes lie at the center of galaxies. The intense gravity at the center should create one, and spiral galaxies are all just pinwheeling "down the drain".
Several things wrong in here. First, it's the huge density at the center of the galaxy that would lead you to think a black hole might form there. Yeah, the density is big there because it's way down in a gravitational potential well. But intense gravity doesn't create a black hole-- quite the other way around, in fact.
Second, spiral galaxies are *not* spiralling down the drain. Most of the stars in a spiral galaxy orbit the center approximately circularly; they aren't spiraling in any more than the earth is spiraling into the Sun. So why the spiral shape? Spiral shape can come from a couple of differnet things. In some galaxies, they are density waves. Think of them as a cosmic "traffic jam". In some places, the stars are closer together than other places; in those places, densities are higher, and gas clouds get compressed, and more stars form (which is why spiral arms are bluer). As the wave passes through those stars, they will spread back out. It's similar to sound waves (which are density waves), or, indeed, clumps of cars on freeways (which seem to maintain their identity even though they don't always have the same cars in them-- you pass through them, so for a while you're a part of the clump, but eventually you get past the clump).
Other theories of spiral structure formation are based on the differential rotation; when a big group of stars form, the differential rotation will tend to stretch it out into a little spiral arm segment. These theories are probably more responsible for spiral structure in galaxies where the arms are ratty and choppy. The density wave theory is probably more responsible in "grand design" spirals where you can trace one long arm all the way from the center out to the edge.
One thing spiral galaxies are definitely not however are stars spinning down the drain the way water spins down a drain. It may look obvious, but it's wrong. (Yes, there are ways to get material to sink down to the center of galaxies, but generally it's a whole lot easier with gas and dust than with stars. Gas and dust are viscous fluids, but stars are basically collisionless.)
Just so you know, any GUI that needs people to "get used to it" is bad design and doesn't take into consideration human factors and usability.
Not really. It's only bad design if your goal is to make the program as easy to learn as possible. In the case of Blender, it means that it's a UI optimized so that those who know it can work as fast as possible. Those optimizations may be inconsistent with optimizations that allow somebody to learn it as fast as possible.
The ideal UI would do both. Given where Blender comes from, the "skilled user efficiency" optimizations were far more important. I suspect there will be a lot of resistance to decreasing the efficiency of the UI to skilled users in the name of improving it for newcomers. If the latter can be done without sacrificing the former, then that will be welcome.
...when I said I could make the big bucks by patenting the use of wiping with toilet paper. I mean, heck, I figured I'd be doing the patent office a favor. Surely the place would start to smell better after they were introduced to this novel technique. The only question for them would be whether there was enough room left for the paper, what with heads up in the way.
Your description sounds like the classic descrption of what Bruce Schneider calls "snake oil". You have a great new encryption algorithm that you've been sitting on.... If you've been sitting on it, nobody knows if it's any good. The best cryptographers don't really know if their algorithm is really any good until lots of other cryptographers have had time to beat on it and test it. The only algorithms that anybody with any sense will use are ones that have been open, and for a long time, so that they can truly be scrutinized.
So, in a word, it doesn't matter. I'd rather you didn't patent it, because software patents are generally evil anyway, and if the algorithm turns out to be useful for something, it could create headaches later. But, as far as cryptography goes, if it is truly as you describe, it's effectively worthless at the moment, and will continue to be so until lots of people have had a chance to see and work on the algorithm.
As this article [jpost.com] points out, one reason big drug companies are stepping away from AIDS drug innovation, at least, is because of AIDS activists and other anticorporate do-gooders. By forcing companies to practically give away their drugs to the third world, these misguided crusaders have removed all incentive from Big Medicine to research new AIDS drugs.
Oh, great, and so thus we should kill off as many of the poor as possible so that drug companies can continue to make their money, huh?
If you assume a profit-oriented pharmaceutial industry, then, yeah, you're right; they can't make their profits if they don't have the ability to limit the availability to those who can pay.
Is this really the system we want?
I strongly believe that (a) pharmaceutical patents should be just flat outlawed-- not granted any more, not enforced, they're just sacrificing life and health on the alter of intellectual property; and (b) medical research should be grant supported like any other reserach. The savings due to lower drug prices from (a) (due to generics being availble, pricing drugs only on the cost of production) could probably more than make up the cost of having to government fund research under (b) (which would, yes, be a huge cost, since it would have to pay all the scientists and researchers, though it wouldn't have to pay the marketing costs that the current system incurs). The advatange of this system is that we would be using the system for funding research that works in all other brances of science. And, the knowledge that comes out of that research would be open, and usable to the best benefit of humanity, rather than primarily to the stock portfolios of those who invest in pharmaceutical companies.
At the graduate level, however, you're supposed to be doing research. How do you define what knowledge is prerequisite for doing research in computer science? You can't -- all you can do is interview the students, get a feel for what sort of projects they are interested in, and decide if those projects sound as though they would be worth a degree.
Things probably are different in the USA. I should disclaim that I'm in Physics&Astronomy, rather than Computer Science, but I suspect many of the same things apply.
A student who goes to grad school knows that he wants to get into research, and, yes, that's what grad school is all about. However, it's the rare student who really knows exactly what he wants to do when he goes to grad school. Many will have some idea as to what field they want to go into-- e.g., in Physics, they may know if they're interested in astro, nuclear, particle, condensed matter, or something else-- and a few students will know what profoessor or project they want to work with, but it's the rare student that knows beyond that.
Part of the purpose of grad school is so that students can learn, in an apprenticeship sort of mode, how to go about doing research. As such, judging them on the ideas for projects they have isn't really fair. Yes, it would increase the quality of grad students, as only the very top ones would ever get in. However, undergraduate education does very little to prepare students for that sort of thing, as that is part of the purpose of graduate education.
On to the GRE's. In Physics, there *is* a core set of knowledge that "any" Physics graduate student ought to have. Indeed, most schools have core courses (or core exams) which the students must take beyond that, to get the basics of the field, before they can be admitted to candidacy (at which point, yes, it is based partly on their presentation of what they will do for their research, and thereafter mostly all they are doing is working on their research). This admission to candidacy will typically come after the student's second year of graduate school. The GRE's give some vague indication (up to the general utility of standardized test, which is a whole different debate) of how well prepared a student is to survive those first two years of graduate classes.
-Rob
As Shakespeare said (more or less)
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Linux Kernel 3.0?
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· Score: 5, Funny
You've gotta wonder what to say to the person when they do something like that... I would generate an analogy, asking them of they pay their cable bill by making the cheque payable to "Cable TV."
Not bad.
Also consider asking if, when shipping a package via UPS, they would make the check out to "Roads and Trucks".
-Rob
Re:Too late. The cat is out of the bag.
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"Squishy" DRM?
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Mozart died nearly penniless, without even the money for a private grave. (He was buried in a mass grave, so we don't know exactly where to go to pay respects.) Yeah, that's a great incentive.
This shows the reach and depth of fear that Microsoft's monopoly can instill in even the biggest and baddest companies on the planet.
How? You think MS told them to fire Perens?
How about this for a try. HPQ makes millions and millions selling Windows only things. MILLIONS. They probably lose money on their Linux divison- but even if they are profitable, its not to the degree (because of scale for sure) of the Windows division.
You go on to answer your own "how". Microsoft doesn't have to have Bill call up Carly and say "fire that Perens bastard" to have a bully-like dominance that causes other companies to dance to its tune. The very fact that Windows is so dominant and that Microsoft is so huge is what prevents true competition from getting a foothold. Microsoft doesn't need bully tactics, they can just carry on like a normal monopoly and everybody will feel bullied anyway. (Of course, we know that Microsoft does in fact use bully tactics; witness them telling Dell that Dell wasn't allowed to sell OS-less PCs.)
It's a powerful 3d modelling/rendering/animation package. It's really quite impressive. You can download a binary version gratis now. (It's not the very latest version, but close; donating members get access to the latest released binary.)
A good full-featured 3d modelleing/rendering package was something that IMHO open source lacked and needed. Blender 3d fits the bill perfectly. Go to www.blender3d.com to learn more and to get the currently available binary.
(Wings 3d is another 3d modelling pacakge, which isn't as far along, but which shows a whole lot of promise. I'm pretty sure Wings 3d is also free software.)
-Rob
Important application left out
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eSuds
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Once Microsoft DRM systems are in place on the washers and dryers, clothing can be checked for DMCA and other copyright/patent/trademark violations. Have a DeCSS shirt? The dryer door locks and refuses to release your clothes until the police can come by and talk to you. Have a company trademark on clothing which is not officially licensed? Likewise.
...is to kill the Supreme Court Betamax decision, now that they find that they'd rather have the ability of perfect control over media. Maybe they're hoping that by killing the technology the suit was over, the ruling will go away...:)
Version of what I call the "James P. Hogan Utopia" show up in a number of his novels. Among them are: Paths to Otherwhere, The Multiplex Man, Return to Tomorrow.
Yes, quit shipping those driver disks. After all, I'm just going to download new drivers... er... and how, exactly, is that going to work for network cards, motherboards, or other critical pieces of the computer?
Honestly, I recommend you buy better hardware, from companies that don't have so many driver problems. I generally don't bother downloading new drivers unless I'm having an issue with the old ones -- or the new ones are substantially faster. And, funny, the drivers that come with the hardware generally work too. But, again, I'm willing to pay a couple bucks more for stuff that works right out of the box. My time is worth far more than fiddling with crap for hours to make it work.
You completely and utterly miss my point, but at least you got to rant, so you got something out of it.
I don't think they should stop shipping the driver disks; sometimes they are necessary sure. However, they have always been completely useless to me. Just as the FreeDOS disk will be useless to most people who buy these Dell PCs. My point is, therefore it's not much of a big deal to include FreeDOS insead of Linux or something else that others might think is "useful".
As for hours of fiddling with crap: every time I've tried to do this, starting with the drviers from the CD has greatly lengthed the amount of time I spent fiddling. If I'd had the good sense to just go to the web and look for updated drivers first, I would have saved time. And while I like fiddling with computers, I don't like fiddling with Windows (since I don't really know it), and do it as little as I can get away with.
(OK, I don't really wish him dead. I just wish him and every other Microsoft exec and lawyer to retire to a quiet life of recreation and contemplation, out of the public eye and completely away from the computer industry.)
..as opposed to a couple of CDs (Linux) which would be very useful to a lot of users?
Would it? I'm not so sure. I suspect that the bulk of their customers will be people who really want OS-less PCs. Even if they're installing Linux, they will install it themselves. Indeed, probably most of the units sold will be going to people building clusters and such, where they have some uniform method of installing the OS everywhere. Anything included with the computer is just useless.
Mind you, it would be nice if Dell started selling desktop Linux systems, with Linux preinstalled and working for the home user. But that's not what this is. Dell has customers who want to be many OSless PCs, and Microsoft was trying to tell Dell that they had to sell Windows to all those customers even though the customers wanted nothing. This is Dell's way of getting around Microsofts terms while still being technically in complaince with the Law of Microsoft.
1. The systems will cost just as much as if you'd ordered them with Windows in the first place.
Given point 1, I fail to see how this is a Big Deal, other than the obvious snub at Microsoft.
It is a pity that you don't get a price break for not having to pay for Windows. On the other hand, I'd be just as happy to know that Microsoft wasn't getting paid a tax out of my money for purchasing a computer.
I may buy a new laptop sometime, on which I'll run some form of Linux. Unfortunatley, it looks like I may have to pay a premium to not buy Windows. All of the best deals on laptops come with Windows preinstalled! You pay more to not have Windows! It's ridiculous. I will have to decide (a) how much money I'm willing to spend to avoid patronizing Microsoft, (b) if there is any real chance of the whole "refund" thing working, or (c) if I should just sell out and bite the bullet and send off the Microsoft tax even though I don't want to buy or use their operating system.
(If anybody can point me to somewhere where you can buy a reaonably priced and reasonably powerful laptop that doesn't have M$ on it (other than Mac-- I'm aware of and considering that option), please let me know.)
I should note that at least a couple of months ago, CompUSA locally was selling OSless PCs. Their advertisement had the added costs for purchasing an OS to go along with it, and Windows did cost more than Red Hat Linux there. Hooray for some actual real costs somehwere. Of course, I suspect the good folks from the computer regulatory government (i.e. Microsoft) will shortly be coming along to stop CompUSA from this dangerous and borderline illegal behavior.
Why not FreeDOS? It doesn't matter. It's just a token.
How much space does FreeDOS take? Perhaps only one CD, or less?
It's pretty clear that Dell does not expect anybody (or much of anybody) to actuall install the included FreeDOS. The FreeDOS is just a maneuver to get around a loophole in Microsoft's licencing agreement. Now they can say, hey, we included an OS, we're abiding by their terms. What they're really doing is selling an OS-less PC, plus an extra CD that adds very little to their costs and might even be useful to a tiny fraction of their customers.
(Heck, I'd rather get a FreeDOS PC than the useless Windows driver disks I get with every piece of hardware I buy. Even when I've installed the drivers on my wife's Windows box so that she can use the printers over the network, I discover they're broken and I have to get updated drivers from the web anyway.)
I'm heartened to see them doing the right thing-- continuing to be willing to sell customers completely legal things that they want to buy even if that is what another very powerful company doesn't want.
On the other hand, it's utterly ridiculous that Dell would even have to perform this end-run around Microsoft's licensing terms in the first place.
Anybody want to place bets on how long it will be before Microsoft changes their licencing terms again to prevent Dell from what they're doing now? (Or perhaps M$ will just tell Dell that they've decided not to licence Windows to them at all; they've used those sorts of threats in the past.)
(Who appointed Microsoft as the regulatory agency for the computer industry anyway?)
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For some reason, I think I remember reading that as matter crosses the event horizon, it's stripped apart at the subatomic level (I suppose due to extreme gravitational forces) and that matter is shot inwards (towards the singulatity), while anti-matter is shot outwards away from the singulatiry. Please do correct me if I'm wrong, but I can look up wherever I read that if you'd like.
You're thinking of Hawking Radiation. It has nothing to do with matter falling through a black hole, but rather with virtual particle/antiparticle pairs that are being created and destroyed everywhere in space all the time. Thanks to Hesienberg's Uncertainty Principle, you can violate the conservation of energy if you do it over a very short period of time. All around us, there's a sort of "froth" in the vacuum made of electrons and antielectrons which spontaneously are created and then annihiliated. It all happens so extremely fast that nobody could observe any violation of conservation of energy.
When this happens right on the event horizon of a black hole, however, you can end up with one particle going into the singularity and the other particle escaping. Now, I don't understand the physics of this process in detail! I should-- I ought to look it up. However, what happens is that if the particle/antiparticle pair is created right at the exact spot, it can happen that rather than annihilating each other, they split and turn into real particles. You can observe the particle coming out, and to keep things balanced, the particle going in then has negative energy. The result is that the black hole loses mass (a very tiny amount, mind you). Over time, therefore, black holes evaporate. (Note that many black holes, esp. those at the center of galaxies, are being fed (and thus growing) much faster than they evaporate due to Hawking radiation.)
The timescale for evaporation of any appreciably sized black hole (solar mass on up to these supermassive black holes) is gigantic-- longer than the age of the universe. Very small ones, though, evaporate pretty quicky. Thus, if there were tiny black holes left over (say) from the Big Bang, we wouldn't expect to find any of them around today.
As for matter falling into a black hole: the tidal forces get larger and larger as you get closer to the black hole. Of course, this happens with any mass. Tidal forces due to being too close to the moon cause the Earth to stretch a bit and its water to slosh around. If you fall into a solar mass black hole, however, even before you got to the event horizon, the difference in the gravitational force on your feet and on your head would tear you apart. This will happen with all black holes, and it's an issue whether you're inside or outside the event horizon. Indeed, the event horizon is largely irrelevant to it, except as a limit of inevitability. For very large black holes, the tidal forces aren't so bad at the event horizon that you ought to be able to drop through it. For solar mass black holes, the tidal forces will kill you long before you can get to the event horizon.If you remember back in 1993 or 1994 when comet Shoemaker-Levy 9 hit Jupiter, it hit in several chunks over the course of several days. The reason was that the comet had been riped apart on a previous pass by Jupiter-- by exactly these same tidal forces. (Comets aren't really held together all that well, as things go, and Jupiter is pretty massive. Tidal forces from Jupiter and the other moons are also what heats up IO and keeps it volcanically active.) My point: tidal forces aren't some mysterious black hole thing, they're something you get with any mass. The only thing about black holes is that you can tend to get a lot closer to that mass than you can with any other form of the smae mass. (E.g., with the Sun, you'd have to be well inside the Sun before the tidal forces got that strong--- but at that point, most of the Sun's mass would be outside your position on the Sun, and therefore you wouldn't be feeling its gravity.)
-Rob
Yes, time dialation approaches infinity as you approach the event horizon, so you can never actually enter a black hole, only mosey up to it :-)
This statement is commonly made, but it's not really accurate.
Yes, from the point of view of a distant observer, somebody falling into a black hole takes an infinite amount of time to do it. However, in the frame of reference of the hole-diver, the coordinates used for the far observer are no good. In fact, the Physics shows that in his frame of reference, the hole-diver goes through the hole in a finite amount of time, and that indeed nothing particularly startling happens at the moment of crossing the event horizon. (Other than it is after that that he will inevitably hit the singularity; however, there's no grand event that signifies the moment of crossing.)
Sounds contradictory, so you will ask, which is "really" right? I like to think about it with this thought experiment. Given an arbitrary amount of energy (and technology and ability to withstand tidal forces and etc.), could the far observer, after waiting an arbitrary amount of time, go in and retrive the hole-diver? If the hole-diver really does take an infinite amount of time to cross, then the answer would be "yes". It would be hard, but in principle the far observer could get the hole-diver. However, the coordinates that apply near the event horizon make it clear that the answer is "no". There eventually comes a time when an external observer, if he waits to long, is inable to retrieve the hole-diver.
What the far observer sees is the photons emitted by the hole-diver. As the hole-diver gets closer and closer to the black hole, the photons get further and further apart (time dilation) and longer and longer in redshift (gravitational redshift). The "last" photon is infinitely redshifted and takes an infinite amount of time to get out-- so the far observer never measures the hole-diver to drop through the hole.
-Rob
I wish people would just be a little more careful in their phrasing, as indeed, black holes themselves are still theories.
Even relativity is only a theory. But I digress.
In fact I'd recommend you be a little more careful with phrasing.... It is a heuristic that when you hear the phrase "only a theory", the person saying it doesn't understand science. I'm not saying that this is the case with you! But your use of that phrase does raise alarm bells.
Lots of things are theories. The theory of gravity, for example. However, just because the theory of gravity is only a theory doesn't mean that a ball won't fall down when I drop it.
Relativity is a theory-- but not "only" a theory. It's a wildly successful theory which has yet to be proven false.
(And note that all scientists still think of Newtonian gravity to be a "correct" theory even though the success of relativity proves it to be "wrong". Newtonian gravity is right because it's the limit of relativity in certain specific cases, i.e. things aren't moving too fast and the gravitational field isn't too intense. In those cases, every test we've made show's that it's right.)
Science can never prove a theory. It can only disprove it. However, when a theory has a long track record of making succesful predictions, we eventually tend to think that it's probably right. Gravity, thermodyanmics, relativity, quantum mechanics, any number of other things are all theories, but that doesn't mean that they're just some wild-eyed speculation that something things "might" be true about the universe. They're all much much more solid than that. Saying something is a "theory" is not at all akin to saying that it is on shaky ground. It merely means that it's the description we use for something in nature, which may be wrong, likely, or on extremely solid ground.
-Rob
I would bet there are black holes at the center of ALL spiral galaxies like our Milky Way. Other shaped galaxies may just be at earlier stages of evolution (such as elliptical) before their holes have formed.
Another point: yes, and no. Yes, most big galaxies probably have huge black holes at their center. But so do most big elliptical galaxies. Also, it is completely inaccurate to say that elliptical galaxies are "earlier in their evolution" than spirals. Once astronomers thought this, but many decades have gone by since then. Ellipticals do not evolve into spirals. What's more, there is evidence in many cases for hugeass black holes at the center of big ellipticals; M87, a large giant elliptical in the Virgo Cluster, is a good example. Many other examples exist. For instance, radio galaxies and quasars (both evidence of nuclear activity attributable to a supermassive black hole) are often found in elliptical galaxies.
(If anything, the evolution may go the other way: by merging enough sprials, you can end up with something that looks more like an elliptical! However, it would be too simplistic to say that "elliptical galaxies all result from mergers of spirals". They're each their own thing, really, with the caveat that shapes can change when galaxies run into each other.)
-Rob
I've always thought it was obvious that super-massive blackholes lie at the center of galaxies. The intense gravity at the center should create one, and spiral galaxies are all just pinwheeling "down the drain".
Several things wrong in here. First, it's the huge density at the center of the galaxy that would lead you to think a black hole might form there. Yeah, the density is big there because it's way down in a gravitational potential well. But intense gravity doesn't create a black hole-- quite the other way around, in fact.
Second, spiral galaxies are *not* spiralling down the drain. Most of the stars in a spiral galaxy orbit the center approximately circularly; they aren't spiraling in any more than the earth is spiraling into the Sun. So why the spiral shape? Spiral shape can come from a couple of differnet things. In some galaxies, they are density waves. Think of them as a cosmic "traffic jam". In some places, the stars are closer together than other places; in those places, densities are higher, and gas clouds get compressed, and more stars form (which is why spiral arms are bluer). As the wave passes through those stars, they will spread back out. It's similar to sound waves (which are density waves), or, indeed, clumps of cars on freeways (which seem to maintain their identity even though they don't always have the same cars in them-- you pass through them, so for a while you're a part of the clump, but eventually you get past the clump).
Other theories of spiral structure formation are based on the differential rotation; when a big group of stars form, the differential rotation will tend to stretch it out into a little spiral arm segment. These theories are probably more responsible for spiral structure in galaxies where the arms are ratty and choppy. The density wave theory is probably more responsible in "grand design" spirals where you can trace one long arm all the way from the center out to the edge.
One thing spiral galaxies are definitely not however are stars spinning down the drain the way water spins down a drain. It may look obvious, but it's wrong. (Yes, there are ways to get material to sink down to the center of galaxies, but generally it's a whole lot easier with gas and dust than with stars. Gas and dust are viscous fluids, but stars are basically collisionless.)
-Rob
Just so you know, any GUI that needs people to "get used to it" is bad design and doesn't take into consideration human factors and usability.
Not really. It's only bad design if your goal is to make the program as easy to learn as possible. In the case of Blender, it means that it's a UI optimized so that those who know it can work as fast as possible. Those optimizations may be inconsistent with optimizations that allow somebody to learn it as fast as possible.
The ideal UI would do both. Given where Blender comes from, the "skilled user efficiency" optimizations were far more important. I suspect there will be a lot of resistance to decreasing the efficiency of the UI to skilled users in the name of improving it for newcomers. If the latter can be done without sacrificing the former, then that will be welcome.
-Rob
...when I said I could make the big bucks by patenting the use of wiping with toilet paper. I mean, heck, I figured I'd be doing the patent office a favor. Surely the place would start to smell better after they were introduced to this novel technique. The only question for them would be whether there was enough room left for the paper, what with heads up in the way.
-Rob
Your description sounds like the classic descrption of what Bruce Schneider calls "snake oil". You have a great new encryption algorithm that you've been sitting on.... If you've been sitting on it, nobody knows if it's any good. The best cryptographers don't really know if their algorithm is really any good until lots of other cryptographers have had time to beat on it and test it. The only algorithms that anybody with any sense will use are ones that have been open, and for a long time, so that they can truly be scrutinized.
So, in a word, it doesn't matter. I'd rather you didn't patent it, because software patents are generally evil anyway, and if the algorithm turns out to be useful for something, it could create headaches later. But, as far as cryptography goes, if it is truly as you describe, it's effectively worthless at the moment, and will continue to be so until lots of people have had a chance to see and work on the algorithm.
-Rob
As this article [jpost.com] points out, one reason big drug companies are stepping away from AIDS drug innovation, at least, is because of AIDS activists and other anticorporate do-gooders. By forcing companies to practically give away their drugs to the third world, these misguided crusaders have removed all incentive from Big Medicine to research new AIDS drugs.
Oh, great, and so thus we should kill off as many of the poor as possible so that drug companies can continue to make their money, huh?
If you assume a profit-oriented pharmaceutial industry, then, yeah, you're right; they can't make their profits if they don't have the ability to limit the availability to those who can pay.
Is this really the system we want?
I strongly believe that (a) pharmaceutical patents should be just flat outlawed-- not granted any more, not enforced, they're just sacrificing life and health on the alter of intellectual property; and (b) medical research should be grant supported like any other reserach. The savings due to lower drug prices from (a) (due to generics being availble, pricing drugs only on the cost of production) could probably more than make up the cost of having to government fund research under (b) (which would, yes, be a huge cost, since it would have to pay all the scientists and researchers, though it wouldn't have to pay the marketing costs that the current system incurs). The advatange of this system is that we would be using the system for funding research that works in all other brances of science. And, the knowledge that comes out of that research would be open, and usable to the best benefit of humanity, rather than primarily to the stock portfolios of those who invest in pharmaceutical companies.
-Rob
At the graduate level, however, you're supposed to be doing research. How do you define what knowledge is prerequisite for doing research in computer science? You can't -- all you can do is interview the students, get a feel for what sort of projects they are interested in, and decide if those projects sound as though they would be worth a degree.
Things probably are different in the USA. I should disclaim that I'm in Physics&Astronomy, rather than Computer Science, but I suspect many of the same things apply.
A student who goes to grad school knows that he wants to get into research, and, yes, that's what grad school is all about. However, it's the rare student who really knows exactly what he wants to do when he goes to grad school. Many will have some idea as to what field they want to go into-- e.g., in Physics, they may know if they're interested in astro, nuclear, particle, condensed matter, or something else-- and a few students will know what profoessor or project they want to work with, but it's the rare student that knows beyond that.
Part of the purpose of grad school is so that students can learn, in an apprenticeship sort of mode, how to go about doing research. As such, judging them on the ideas for projects they have isn't really fair. Yes, it would increase the quality of grad students, as only the very top ones would ever get in. However, undergraduate education does very little to prepare students for that sort of thing, as that is part of the purpose of graduate education.
On to the GRE's. In Physics, there *is* a core set of knowledge that "any" Physics graduate student ought to have. Indeed, most schools have core courses (or core exams) which the students must take beyond that, to get the basics of the field, before they can be admitted to candidacy (at which point, yes, it is based partly on their presentation of what they will do for their research, and thereafter mostly all they are doing is working on their research). This admission to candidacy will typically come after the student's second year of graduate school. The GRE's give some vague indication (up to the general utility of standardized test, which is a whole different debate) of how well prepared a student is to survive those first two years of graduate classes.
-Rob
A rose by any other name would still have thorns.
The title of the poem you're thinking of is "The Road Not Taken." It would also be a good idea for you to re-read the poem
Er... maybe you should re-read the poem. The last stanza in particular. That's where the quote comes from.
-Rob
You've gotta wonder what to say to the person when they do something like that... I would generate an analogy, asking them of they pay their cable bill by making the cheque payable to "Cable TV."
Not bad.
Also consider asking if, when shipping a package via UPS, they would make the check out to "Roads and Trucks".
-Rob
Mozart died nearly penniless, without even the money for a private grave. (He was buried in a mass grave, so we don't know exactly where to go to pay respects.) Yeah, that's a great incentive.
Myth.
http://europeanhistory.about.com/library/bldyk11 .htm
-Rob
This shows the reach and depth of fear that Microsoft's monopoly can instill in even the biggest and baddest companies on the planet.
How? You think MS told them to fire Perens?
How about this for a try. HPQ makes millions and millions selling Windows only things. MILLIONS. They probably lose money on their Linux divison- but even if they are profitable, its not to the degree (because of scale for sure) of the Windows division.
You go on to answer your own "how". Microsoft doesn't have to have Bill call up Carly and say "fire that Perens bastard" to have a bully-like dominance that causes other companies to dance to its tune. The very fact that Windows is so dominant and that Microsoft is so huge is what prevents true competition from getting a foothold. Microsoft doesn't need bully tactics, they can just carry on like a normal monopoly and everybody will feel bullied anyway. (Of course, we know that Microsoft does in fact use bully tactics; witness them telling Dell that Dell wasn't allowed to sell OS-less PCs.)
-Rob
So, blender is what?
It's a powerful 3d modelling/rendering/animation package. It's really quite impressive. You can download a binary version gratis now. (It's not the very latest version, but close; donating members get access to the latest released binary.)
A good full-featured 3d modelleing/rendering package was something that IMHO open source lacked and needed. Blender 3d fits the bill perfectly. Go to www.blender3d.com to learn more and to get the currently available binary.
(Wings 3d is another 3d modelling pacakge, which isn't as far along, but which shows a whole lot of promise. I'm pretty sure Wings 3d is also free software.)
-Rob
Once Microsoft DRM systems are in place on the washers and dryers, clothing can be checked for DMCA and other copyright/patent/trademark violations. Have a DeCSS shirt? The dryer door locks and refuses to release your clothes until the police can come by and talk to you. Have a company trademark on clothing which is not officially licensed? Likewise.
-Rob
...is to kill the Supreme Court Betamax decision, now that they find that they'd rather have the ability of perfect control over media. Maybe they're hoping that by killing the technology the suit was over, the ruling will go away... :)
-Rob
Version of what I call the "James P. Hogan Utopia" show up in a number of his novels. Among them are: Paths to Otherwhere, The Multiplex Man, Return to Tomorrow.
-Rob
Yes, quit shipping those driver disks. After all, I'm just going to download new drivers... er... and how, exactly, is that going to work for network cards, motherboards, or other critical pieces of the computer?
Honestly, I recommend you buy better hardware, from companies that don't have so many driver problems. I generally don't bother downloading new drivers unless I'm having an issue with the old ones -- or the new ones are substantially faster. And, funny, the drivers that come with the hardware generally work too. But, again, I'm willing to pay a couple bucks more for stuff that works right out of the box. My time is worth far more than fiddling with crap for hours to make it work.
You completely and utterly miss my point, but at least you got to rant, so you got something out of it.
I don't think they should stop shipping the driver disks; sometimes they are necessary sure. However, they have always been completely useless to me. Just as the FreeDOS disk will be useless to most people who buy these Dell PCs. My point is, therefore it's not much of a big deal to include FreeDOS insead of Linux or something else that others might think is "useful".
As for hours of fiddling with crap: every time I've tried to do this, starting with the drviers from the CD has greatly lengthed the amount of time I spent fiddling. If I'd had the good sense to just go to the web and look for updated drivers first, I would have saved time. And while I like fiddling with computers, I don't like fiddling with Windows (since I don't really know it), and do it as little as I can get away with.
-Rob
I saw your message with .sig attached:
Bill Gates.
--
-- He's dead, Jim.
If only!
(OK, I don't really wish him dead. I just wish him and every other Microsoft exec and lawyer to retire to a quiet life of recreation and contemplation, out of the public eye and completely away from the computer industry.)
-Rob
Would it? I'm not so sure. I suspect that the bulk of their customers will be people who really want OS-less PCs. Even if they're installing Linux, they will install it themselves. Indeed, probably most of the units sold will be going to people building clusters and such, where they have some uniform method of installing the OS everywhere. Anything included with the computer is just useless.
Mind you, it would be nice if Dell started selling desktop Linux systems, with Linux preinstalled and working for the home user. But that's not what this is. Dell has customers who want to be many OSless PCs, and Microsoft was trying to tell Dell that they had to sell Windows to all those customers even though the customers wanted nothing. This is Dell's way of getting around Microsofts terms while still being technically in complaince with the Law of Microsoft.
-Rob
1. The systems will cost just as much as if you'd ordered them with Windows in the first place.
Given point 1, I fail to see how this is a Big Deal, other than the obvious snub at Microsoft.
It is a pity that you don't get a price break for not having to pay for Windows. On the other hand, I'd be just as happy to know that Microsoft wasn't getting paid a tax out of my money for purchasing a computer.
I may buy a new laptop sometime, on which I'll run some form of Linux. Unfortunatley, it looks like I may have to pay a premium to not buy Windows. All of the best deals on laptops come with Windows preinstalled! You pay more to not have Windows! It's ridiculous. I will have to decide (a) how much money I'm willing to spend to avoid patronizing Microsoft, (b) if there is any real chance of the whole "refund" thing working, or (c) if I should just sell out and bite the bullet and send off the Microsoft tax even though I don't want to buy or use their operating system.
(If anybody can point me to somewhere where you can buy a reaonably priced and reasonably powerful laptop that doesn't have M$ on it (other than Mac-- I'm aware of and considering that option), please let me know.)
I should note that at least a couple of months ago, CompUSA locally was selling OSless PCs. Their advertisement had the added costs for purchasing an OS to go along with it, and Windows did cost more than Red Hat Linux there. Hooray for some actual real costs somehwere. Of course, I suspect the good folks from the computer regulatory government (i.e. Microsoft) will shortly be coming along to stop CompUSA from this dangerous and borderline illegal behavior.
-Rob
Why not FreeDOS? It doesn't matter. It's just a token.
How much space does FreeDOS take? Perhaps only one CD, or less?
It's pretty clear that Dell does not expect anybody (or much of anybody) to actuall install the included FreeDOS. The FreeDOS is just a maneuver to get around a loophole in Microsoft's licencing agreement. Now they can say, hey, we included an OS, we're abiding by their terms. What they're really doing is selling an OS-less PC, plus an extra CD that adds very little to their costs and might even be useful to a tiny fraction of their customers.
(Heck, I'd rather get a FreeDOS PC than the useless Windows driver disks I get with every piece of hardware I buy. Even when I've installed the drivers on my wife's Windows box so that she can use the printers over the network, I discover they're broken and I have to get updated drivers from the web anyway.)
-Rob
I'm heartened to see them doing the right thing-- continuing to be willing to sell customers completely legal things that they want to buy even if that is what another very powerful company doesn't want.
On the other hand, it's utterly ridiculous that Dell would even have to perform this end-run around Microsoft's licensing terms in the first place.
Anybody want to place bets on how long it will be before Microsoft changes their licencing terms again to prevent Dell from what they're doing now? (Or perhaps M$ will just tell Dell that they've decided not to licence Windows to them at all; they've used those sorts of threats in the past.)
(Who appointed Microsoft as the regulatory agency for the computer industry anyway?)
-Rob