Actually, I use emacs. But I really appreciate people who can grok vim (I can't). =D
Funny. I'm just the opposite. When I first started using linux (1998 or 1999), I knew that vi and emacs existed, so I tried both. I completely failed to understand emacs in the slightest, whereas I grasped vi rather dimly.
Thus, my use of vi continued and greatly improved, and my use of emacs is nonexistent. But I do feel slightly in awe of people who grok emacs, simply because I can't.
Sorry to be didactic, but shouldn't it be "tho'" rather than "'tho"? It seems that it is the end of the word that has been contracted rather than the beginning.
Yay for Richardson! That's my hometown! (well, I've only lived there for a couple months out of the last couple years, but still. I grew up there. My parents still live there. It's home.)
As a side note, I actually verbed architect the other day as well. Or... no, on second thought I actually verbed architecture. As in "The program should be architectured more modularly.".
Sure you do. Enclose your entire property in a Faraday Cage, and then never leave it. You've still got perfect freedom of choice to be a nut. For that matter, you could also cover your entire body in tinfoil, although copperfoil or silverfoil would make a better conductor, and therefore a better Faraday Cage.
In a talk I went to last summer about neutrinos, the statistic was given that, on average, approximately 8 (or maybe it was 13) neutrinos would interact with your body over the course of your lifetime.
Of course, the standard deviation on that number is crazy high... if N is the number of neutrinos passing through your body over the course of your lifetime, then the variance (square of the std dev) is going to be (using a binomial distribution, which seems the correct choice) N (8/N) (1 - 8/N), or 8(N-8)/N, which asymptotically approaches 8 as N increases. (or, if I remember incorrectly, and the actual number was 13, then do s/8/13/)
Anyway, the point is the same. Neutrinos do not present a serious danger.
The lowest electronic energy level goes like Z, and X-rays start at about 100 eV. So you could easily get a soft X-ray out of something as small as oxygen or neon, which while not common are hardly the unstable transuranics you're talking about.
True. I failed to bother to figure out what atomic number it takes to start radiating x-rays. However, it is still true that anything much heavier than hydrogen or helium does not account for much of the mass falling into most black holes. Additionally, in order for us to detect even a soft xray here on earth, far from the black hole, a very very hard xray indeed would have to be emitted near the black hole, due to the redshifting.
Also, I do not know nearly so much about plasmas, so I suppose you might be right. I'm a bit puzzled by the black body radiation bit though. I wouldn't imagine (just based on intuition) that a plasma would be a black body. Then again, thinking about it some more, I suppose it would be.
Forgive me for things I didn't think out thoroughly, it was 1:30 am.
mkay. I suppose I hadn't considered that. Of course, it would have to be raised quite far into the thermal x-ray range in order to make up for the gravitational redshift.
No, it is termed dark because as you say, it does not radiate. Although, depending on how quantum mechanics and gravity get reconciled, it might be determined to be emitting gravitational force particles. After all, the way that we know about it is due to its gravitational effects. The fact that we manage to detect it more directly would have no effect on whether or not it radiates, thus it would still be dark. Of course, if we determined what it was because we found that it was emitting some previously unknown form of radiation, then it might lose the "dark" moniker.
Yes, I do know the difference between a hot field and something which eventually turns out to be accepted theory.
And no, I don't think that being a hot field would mean that there were no flaws. In fact, if there were no flaws, it would far more likely be what is known as a dead field, at least when it comes to theory. Experimentalists could still be checking it for ages, of course.
The OP claimed dark matter and dark energy were dead fields already due not to them being absolutely correct, but due to them being unequivocably wrong. My point was that this is not the case currently. I never claimed that it was "the truth" or even implied that I believed it to be "the truth". So, I fail to understand the cause for your last statement.
Not really. It is not just being unidentified that makes it "dark", it really is dark. We can estimate from large scale observation of various cosmological trends (not sure exactly how, cosmology and astronomy are not my fields) how much matter/energy is in the universe. We can also count up how much matter we can see (because it is luminous, like stars or quasars). The two numbers don't match up. Not even remotely. The latter is something like 30% of the former. So, we conclude that there is a great deal of matter/energy out there that we simply cannot see, hence it is "dark". The problem is that nobody knows exactly what form it takes. But knowing that form doesn't necessarily make it no longer dark, it just means that we know what it is that is out there not emitting light.
It is NOT due to heat, or friction, or any sort of thermal radiation. Hydrogen (the most common thing approaching a black hole, and due to tidal forces, anything larger would get ripped apart anyway (the hydrogen gets ripped apart too)) simply cannot ever emit radiation of that frequency due to thermal effects. The highest frequency thermal radiation of hydrogen is in the ultraviolet, nowhere near xrays. Furthermore, due to redshifting, the actual frequency emitted in the hydrogen atom's frame of reference is much much higher than xray range, making it even more implausible that the xray emissions are due to thermal radiation.
Most of the replies to this post have assigned it to some form of thermal radiation, whatever the cause of the heat, but this is simply wrong. See my other post for details why.
If we assume that almost exclusively extremely heavy elements are falling in to most black holes, then thermal radiation could be the source, but this is simply ridiculous for 2 reasons: 1) elements that heavy are ridiculously unstable, and thus do not occur in nature (at least not for long) and 2) tidal forces from the proximity of the black hole would actually increase their instability, so that even if there were large clouds of these elements drifting around, they would not survive to get close enough to the black hole to begin emitting.
Disclaimer: IANAPhysicist... yet. I am about to start my senior level undergrad classes as a physics major, and have worked for the last two summers at Fermi National Accelerator Labratory.
The X rays emitted have essentially nothing to do with the heat of matter falling in, and everything to do with acceleration of charged particles. In fact, it'd be nearly impossible to actually get any substance "xray hot" as you put it.
When you heat a substance, it radiates, of course. This occurs due to electrons changing energy levels. These energy levels are very precisely defined, and thus the emission spectrum consists of sharp lines (they are not perfectly sharp due to perturbations like spin-orbit coupling, etc.). Then, in a macroscopic situation, many of the emitted photons will scatter off of other atoms, losing some energy in the process. By this mechanism, the sharp spectral lines get very blurred, and we see an essentially continuous spectrum (as long as you restrict it to middle range frequencies) with bright lines at the spectral emission frequencies.
The reason that this process doesn't produce xrays, no matter how hot you get the substance is that the energy levels an electron could be in do not range from 0 to infinity. In fact, in the case of a hydrogen atom, suppose we take an electron in the lowest energy shell to have 0 potential energy. Well then, now we move that electron to an infinite distance from the proton. At this point, it will have lost ~13.6 electron volts of energy. Thus, the highest energy photon that a hydrogen atom can emit due to an electron changing energy levels is just 13.6 eV. This falls in the ultraviolet range. And then, by scattering off other atoms, photons only lose energy, rather than gaining it.
Now, strictly speaking, as we increase the nuclear size, the difference in the energy levels will increase, and the energy of the emitted photons will be higher. So, if we used heavy enough elements, we could conceivably get them "xray hot". But by that point, we would very likely have reached the ultra-unstable elements that have only been created for very brief periods of time in the lab before decaying. Obviously, these are not found in great quantity in nature.
So, now that we know that heat isn't the culprit, how do we get xrays from black holes?
Well, I could be mistaken, and if so, I hope someone less mistaken than me happens on this post to correct me, but I believe that it primarily occurs because first, the atoms are ripped apart by tidal forces (they are "spaghettified"), leaving the electrons and the nuclei separated. Then, obviously, these particles are accelerating, and accelerating charged particles generates electromagnetic radiation. The greater the acceleration, the higher the frequency of the radiation generated. And since the gravitational force of the black hole increases as you get closer, the acceleration will proceed at a higher and higher rate, so the frequency of emitted radiation from one individual particle should slide upwards. Of course, that doesn't take into account gravitational redshifting, so perhaps the two effects cancel each other out nicely, leaving us with xrays.
I've still got my IBM keyboard. It came with the first computer I ever owned (and still own, it is in the closet of my room at my parents' house): An authentic IBM Personal System/2 Model 8556. Made in 1993, it sported a 486SX (no heatsink or fan needed here!) at 50mHz, MDA graphics, a token ring adapter, external SCSI port, internal XT hard drive (200MB, I've got more than twice that much RAM now), 3.5" floppy drive, 16MB RAM, excessively crappy mouse, equally crappy 14" monitor, and a wonderful wonderful keyboard. All for 25$ at my scout troop's rummage sale.
I am typing on that keyboard right now. Yes, it is hellishly loud, but the feel of the keys is unmistakable, and I never, ever have problems with keys sticking, or not responding, or any of the things I hate about almost every other keyboard I've ever used. Plus, the key caps come off easily, and most are interchangeable... This is fun. My little sister is perpetually confused by the arrow keys (point in opposite directions), and most people have a hard time with the swapped F-key row and numeral row.
But, suffice it to say, this 12 year old keyboard is the most beloved and probably most irreplaceable part of my computer today.
Libel: http://dictionary.reference.com/search?q=libel
1. A false publication, as in writing, print, signs, or pictures, that damages a person's reputation.
2. The act of presenting such material to the public.
This is a published piece of writing. It is false (claims that most linux developers spend their nights writing windows viruses). It damages a person's reputation (see virus claim above).
Thus, it is libel. Libel happens to be illegal in the United States. Whether or not you think it should be illegal is another matter entirely, the fact remains that it is.
I'm actually at the end of my first year as a theory postgrad, so my brain still hurts from a year of having field theory pumped into it. In about a week and a half, I get shipped off (along with all my UK peers) to a summer school in the Lake District, which is on the other end of the country.
Perhaps "monopolist" is intended to mean not someone who merely has a monopoly, but someone who has a monopoly and abuses it.
Not saying that it necessarily does; you're probably right and slashdotters are misusing it. However, there is that possible interpretation of the word. And yes, there are millions of possible interpretations, but I find this one plausible as well.
It's kind of like a Venus Flytrap for hackers. They are lured in by the sweet smeel of the nectar coating, and then SNAP. Nothing left for them to do but be slowly, painfully, excrutiatingly digested alive... Something like that anyway.
OT, but...
I find it very odd that the only person I've ever met who had the last name Carmack also had the first name John, but wasn't the programming talent you speak of. He plays the trumpet and sings quite well, but he does not program.
Carmack is not a particularly common name, AFAIK. Every time I see John Carmack mentioned, it kinda throws me for a loop.
mkay. That's cool. If you had an interest in continued conversation, I doubt anyone is following this thread particularly, so I don't really feel worried at all about posting my email: j s w (a.t) fnal,
gov
(Just trying to break it up so spambots don't grab it)
Unfortunately, I'm just a lowly undergrad working here for the summer, and I'll actually be leaving to go back to class in a week and a half. But I'm part of an ongoing research group in HEP at my university, so I know it is not the end of my association with FNAL.
One more crippling bombshell hit the already flagging SuSE community today, as Slashdot user Shinaku announced the results of his extensive IRC survey. "The amount of people using SuSE has dropped considerably," says Shinaku. Clearly this does not bode well for users of the once popular Linux distribution owned by Novell. This news only serves to reinforce what we already knew: SuSE is collapsing like a punctured Goodyear blimp. The rats have already jumped ship, as several chief developers of the distribution have moved to Redmond, WA, citing their plans to "stand on street corners with signs reading 'Will code for mountain dew'." The only question now is how long before the end?
You don't need to be an IRC analyst to predict SuSE's future. The writing is on the wall. SuSE faces hard times ahead, as its user base continues to drop considerably in days to come.
Predatory distros such as Ubuntu and PuppyLinux grow fat on the blood of the innocent, wooing poor naive users away from the loving arms of Novell and then leaving them with nothing but a smoking hole where their hearts used to be.
Novell's latest move, Open Sourcing SuSE, is seen by some as the dying gasp: A valiant attempt, but just as surely a failure. It has often been compared to Custer's Last Stand at the Battle of Little Bighorn. John Dvorak, well known and respected writer, has gone on record as saying that Novell is expected to sell SuSE to SCO before the end of summer.
Slashdot Mirror
Actually, I use emacs. But I really appreciate people who can grok vim (I can't). =D
Funny. I'm just the opposite. When I first started using linux (1998 or 1999), I knew that vi and emacs existed, so I tried both. I completely failed to understand emacs in the slightest, whereas I grasped vi rather dimly.
Thus, my use of vi continued and greatly improved, and my use of emacs is nonexistent. But I do feel slightly in awe of people who grok emacs, simply because I can't.
Sorry to be didactic, but shouldn't it be "tho'" rather than "'tho"? It seems that it is the end of the word that has been contracted rather than the beginning.
Yay for Richardson! That's my hometown! (well, I've only lived there for a couple months out of the last couple years, but still. I grew up there. My parents still live there. It's home.)
PygmySurfer (442860)
Your UID isn't low enough. Clearly you're not old enough to be a Real Programmer.
Not that I'm saying I am, of course, not with UID 780K+...
I have no choice in letting permeate my body.
Sure you do. Enclose your entire property in a Faraday Cage, and then never leave it. You've still got perfect freedom of choice to be a nut. For that matter, you could also cover your entire body in tinfoil, although copperfoil or silverfoil would make a better conductor, and therefore a better Faraday Cage.
In a talk I went to last summer about neutrinos, the statistic was given that, on average, approximately 8 (or maybe it was 13) neutrinos would interact with your body over the course of your lifetime.
Of course, the standard deviation on that number is crazy high... if N is the number of neutrinos passing through your body over the course of your lifetime, then the variance (square of the std dev) is going to be (using a binomial distribution, which seems the correct choice) N (8/N) (1 - 8/N), or 8(N-8)/N, which asymptotically approaches 8 as N increases. (or, if I remember incorrectly, and the actual number was 13, then do s/8/13/)
Anyway, the point is the same. Neutrinos do not present a serious danger.
The lowest electronic energy level goes like Z, and X-rays start at about 100 eV. So you could easily get a soft X-ray out of something as small as oxygen or neon, which while not common are hardly the unstable transuranics you're talking about.
True. I failed to bother to figure out what atomic number it takes to start radiating x-rays. However, it is still true that anything much heavier than hydrogen or helium does not account for much of the mass falling into most black holes. Additionally, in order for us to detect even a soft xray here on earth, far from the black hole, a very very hard xray indeed would have to be emitted near the black hole, due to the redshifting.
Also, I do not know nearly so much about plasmas, so I suppose you might be right. I'm a bit puzzled by the black body radiation bit though. I wouldn't imagine (just based on intuition) that a plasma would be a black body. Then again, thinking about it some more, I suppose it would be.
Forgive me for things I didn't think out thoroughly, it was 1:30 am.
mkay. I suppose I hadn't considered that. Of course, it would have to be raised quite far into the thermal x-ray range in order to make up for the gravitational redshift.
No, it is termed dark because as you say, it does not radiate. Although, depending on how quantum mechanics and gravity get reconciled, it might be determined to be emitting gravitational force particles. After all, the way that we know about it is due to its gravitational effects. The fact that we manage to detect it more directly would have no effect on whether or not it radiates, thus it would still be dark. Of course, if we determined what it was because we found that it was emitting some previously unknown form of radiation, then it might lose the "dark" moniker.
Yes, I do know the difference between a hot field and something which eventually turns out to be accepted theory.
And no, I don't think that being a hot field would mean that there were no flaws. In fact, if there were no flaws, it would far more likely be what is known as a dead field, at least when it comes to theory. Experimentalists could still be checking it for ages, of course.
The OP claimed dark matter and dark energy were dead fields already due not to them being absolutely correct, but due to them being unequivocably wrong. My point was that this is not the case currently. I never claimed that it was "the truth" or even implied that I believed it to be "the truth". So, I fail to understand the cause for your last statement.
Not really. It is not just being unidentified that makes it "dark", it really is dark. We can estimate from large scale observation of various cosmological trends (not sure exactly how, cosmology and astronomy are not my fields) how much matter/energy is in the universe. We can also count up how much matter we can see (because it is luminous, like stars or quasars). The two numbers don't match up. Not even remotely. The latter is something like 30% of the former. So, we conclude that there is a great deal of matter/energy out there that we simply cannot see, hence it is "dark". The problem is that nobody knows exactly what form it takes. But knowing that form doesn't necessarily make it no longer dark, it just means that we know what it is that is out there not emitting light.
Actually... dark energy is one of the hottest fields in physics right now... I'd sure like to see the source for your statements.
It is NOT due to heat, or friction, or any sort of thermal radiation. Hydrogen (the most common thing approaching a black hole, and due to tidal forces, anything larger would get ripped apart anyway (the hydrogen gets ripped apart too)) simply cannot ever emit radiation of that frequency due to thermal effects. The highest frequency thermal radiation of hydrogen is in the ultraviolet, nowhere near xrays. Furthermore, due to redshifting, the actual frequency emitted in the hydrogen atom's frame of reference is much much higher than xray range, making it even more implausible that the xray emissions are due to thermal radiation.
Most of the replies to this post have assigned it to some form of thermal radiation, whatever the cause of the heat, but this is simply wrong. See my other post for details why.
If we assume that almost exclusively extremely heavy elements are falling in to most black holes, then thermal radiation could be the source, but this is simply ridiculous for 2 reasons: 1) elements that heavy are ridiculously unstable, and thus do not occur in nature (at least not for long) and 2) tidal forces from the proximity of the black hole would actually increase their instability, so that even if there were large clouds of these elements drifting around, they would not survive to get close enough to the black hole to begin emitting.
Disclaimer: IANAPhysicist... yet. I am about to start my senior level undergrad classes as a physics major, and have worked for the last two summers at Fermi National Accelerator Labratory.
Wrong in part.
The X rays emitted have essentially nothing to do with the heat of matter falling in, and everything to do with acceleration of charged particles. In fact, it'd be nearly impossible to actually get any substance "xray hot" as you put it.
When you heat a substance, it radiates, of course. This occurs due to electrons changing energy levels. These energy levels are very precisely defined, and thus the emission spectrum consists of sharp lines (they are not perfectly sharp due to perturbations like spin-orbit coupling, etc.). Then, in a macroscopic situation, many of the emitted photons will scatter off of other atoms, losing some energy in the process. By this mechanism, the sharp spectral lines get very blurred, and we see an essentially continuous spectrum (as long as you restrict it to middle range frequencies) with bright lines at the spectral emission frequencies.
The reason that this process doesn't produce xrays, no matter how hot you get the substance is that the energy levels an electron could be in do not range from 0 to infinity. In fact, in the case of a hydrogen atom, suppose we take an electron in the lowest energy shell to have 0 potential energy. Well then, now we move that electron to an infinite distance from the proton. At this point, it will have lost ~13.6 electron volts of energy. Thus, the highest energy photon that a hydrogen atom can emit due to an electron changing energy levels is just 13.6 eV. This falls in the ultraviolet range. And then, by scattering off other atoms, photons only lose energy, rather than gaining it.
Now, strictly speaking, as we increase the nuclear size, the difference in the energy levels will increase, and the energy of the emitted photons will be higher. So, if we used heavy enough elements, we could conceivably get them "xray hot". But by that point, we would very likely have reached the ultra-unstable elements that have only been created for very brief periods of time in the lab before decaying. Obviously, these are not found in great quantity in nature.
So, now that we know that heat isn't the culprit, how do we get xrays from black holes?
Well, I could be mistaken, and if so, I hope someone less mistaken than me happens on this post to correct me, but I believe that it primarily occurs because first, the atoms are ripped apart by tidal forces (they are "spaghettified"), leaving the electrons and the nuclei separated. Then, obviously, these particles are accelerating, and accelerating charged particles generates electromagnetic radiation. The greater the acceleration, the higher the frequency of the radiation generated. And since the gravitational force of the black hole increases as you get closer, the acceleration will proceed at a higher and higher rate, so the frequency of emitted radiation from one individual particle should slide upwards. Of course, that doesn't take into account gravitational redshifting, so perhaps the two effects cancel each other out nicely, leaving us with xrays.
I've still got my IBM keyboard. It came with the first computer I ever owned (and still own, it is in the closet of my room at my parents' house): An authentic IBM Personal System/2 Model 8556. Made in 1993, it sported a 486SX (no heatsink or fan needed here!) at 50mHz, MDA graphics, a token ring adapter, external SCSI port, internal XT hard drive (200MB, I've got more than twice that much RAM now), 3.5" floppy drive, 16MB RAM, excessively crappy mouse, equally crappy 14" monitor, and a wonderful wonderful keyboard. All for 25$ at my scout troop's rummage sale.
I am typing on that keyboard right now. Yes, it is hellishly loud, but the feel of the keys is unmistakable, and I never, ever have problems with keys sticking, or not responding, or any of the things I hate about almost every other keyboard I've ever used. Plus, the key caps come off easily, and most are interchangeable... This is fun. My little sister is perpetually confused by the arrow keys (point in opposite directions), and most people have a hard time with the swapped F-key row and numeral row.
But, suffice it to say, this 12 year old keyboard is the most beloved and probably most irreplaceable part of my computer today.
scotopic
What? What about SCO? They're suing the inventor of the lightbulb now?
Libel: http://dictionary.reference.com/search?q=libel
1. A false publication, as in writing, print, signs, or pictures, that damages a person's reputation.
2. The act of presenting such material to the public.
This is a published piece of writing. It is false (claims that most linux developers spend their nights writing windows viruses). It damages a person's reputation (see virus claim above).
Thus, it is libel. Libel happens to be illegal in the United States. Whether or not you think it should be illegal is another matter entirely, the fact remains that it is.
I'm actually at the end of my first year as a theory postgrad, so my brain still hurts from a year of having field theory pumped into it. In about a week and a half, I get shipped off (along with all my UK peers) to a summer school in the Lake District, which is on the other end of the country.
Good luck to you!
Perhaps "monopolist" is intended to mean not someone who merely has a monopoly, but someone who has a monopoly and abuses it.
Not saying that it necessarily does; you're probably right and slashdotters are misusing it. However, there is that possible interpretation of the word. And yes, there are millions of possible interpretations, but I find this one plausible as well.
It's kind of like a Venus Flytrap for hackers. They are lured in by the sweet smeel of the nectar coating, and then SNAP. Nothing left for them to do but be slowly, painfully, excrutiatingly digested alive... Something like that anyway.
OT, but...
I find it very odd that the only person I've ever met who had the last name Carmack also had the first name John, but wasn't the programming talent you speak of. He plays the trumpet and sings quite well, but he does not program.
Carmack is not a particularly common name, AFAIK. Every time I see John Carmack mentioned, it kinda throws me for a loop.
mkay. That's cool. If you had an interest in continued conversation, I doubt anyone is following this thread particularly, so I don't really feel worried at all about posting my email: j s w (a.t) fnal,
gov
(Just trying to break it up so spambots don't grab it)
Unfortunately, I'm just a lowly undergrad working here for the summer, and I'll actually be leaving to go back to class in a week and a half. But I'm part of an ongoing research group in HEP at my university, so I know it is not the end of my association with FNAL.
SUSE IS DEAD
One more crippling bombshell hit the already flagging SuSE community today, as Slashdot user Shinaku announced the results of his extensive IRC survey. "The amount of people using SuSE has dropped considerably," says Shinaku. Clearly this does not bode well for users of the once popular Linux distribution owned by Novell. This news only serves to reinforce what we already knew: SuSE is collapsing like a punctured Goodyear blimp. The rats have already jumped ship, as several chief developers of the distribution have moved to Redmond, WA, citing their plans to "stand on street corners with signs reading 'Will code for mountain dew'." The only question now is how long before the end?
You don't need to be an IRC analyst to predict SuSE's future. The writing is on the wall. SuSE faces hard times ahead, as its user base continues to drop considerably in days to come. Predatory distros such as Ubuntu and PuppyLinux grow fat on the blood of the innocent, wooing poor naive users away from the loving arms of Novell and then leaving them with nothing but a smoking hole where their hearts used to be.
Novell's latest move, Open Sourcing SuSE, is seen by some as the dying gasp: A valiant attempt, but just as surely a failure. It has often been compared to Custer's Last Stand at the Battle of Little Bighorn. John Dvorak, well known and respected writer, has gone on record as saying that Novell is expected to sell SuSE to SCO before the end of summer.
The error of margin in this survey is 3%.
Where are you working?