Re:Um, if it's a star it can't be dark matter....
on
"Dark Matter" Observed
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· Score: 2
Right, that was my point. Since we can see this object (see image in article), it can't strictly be called dark matter. OK, that's pretty specious, but see my other posts in this thread for a longer explanation.
Executive Summary: we already knew objects like this existed, and we think we know how many there are in the milky way, so it can't really be part of the solution to the missing mass problem.
Re:Um, if it's a star it can't be dark matter....
on
"Dark Matter" Observed
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· Score: 2
Pretty good point, but there's a big difference between a failed star (or brown dwarf) and a low-mass star like this object. We have a pretty good idea how many low-mass stars there are in the Galaxy, from the statistics of stars in our neighborhood. We already account for the presence of such objects when we compute the mass of known objects in our Galaxy. This object is in the "known" column of the Galactic Census; it isn't missing mass.
Now, if you want to discuss the uncertainty of the low-mass stellar mass function, and say that it's possible that there are lots more of these dim stars than we currently estimate, that's a different story (although no one would recommend making this argument based on the observation of a single object). However, there can't be so many of these little guys as to solve the missing mass problem.
"Observations of clusters of galaxies and
the large scale structure of individual galaxies tell us that no more than a quarter of the total amount of matter in the Universe consists of normal atoms and molecules that make up the familiar world around us."
IOW, at least 75 percent of the universe is made of something other than protons, neutrons and electrons. This dim star is in the 25 percent "normal matter" minority.
We are already pretty sure that most of the missing matter must be non-baryonic (i.e., it must be made of something other than protons, neutrons and electrons).
Um, if it's a star it can't be dark matter....
on
"Dark Matter" Observed
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· Score: 4, Interesting
The observed object is a dwarf star. It is luminous. This article should have been titled "Confirmation that one of the MACHO objects is not Dark Matter".
I mostly agree. I don't object to rich guys shelling out the dough for orbital joyrides (because, as others have pointed out, this should eventually drive costs down, and maybe someday I'll be a not-rich guy on an orbital joyride).
However, I think that if NASA is the one doing it, such commercialization would be a Bad Thing. Instead, it should be handled by private "space tourism" companies.
"The extra lense introduces a data loss. It will be removed in 2003"
Yeah, okay, no optic is perfect, but the loss caused by COSTAR is not significant.
Just FYI, while COSTAR won't be physically removed until 2003, it was permanently retracted out of the optical path a few weeks ago, in anticipation of the removal of the faint object spectrograph early next year (the last instrument that doesn't internally correct for Hubble's aberration).
It's not a good analogy, because the correction used by Paranal is an adaptive optics system that continually updates the shape of the mirror 500 times per second to correct for the turbulent atmosphere, which causes images to bounce around in the focal plane (a/k/a the "twinkling" of stars). OTOH, the HST correction is static aberration correction, and therefore much simpler, technologically. HST doesn't need adaptive optics, because there is no atmosphere between it and its targets (that was the whole point of putting it in orbit).
Furthermore, even if the HST mirror had been manufactured perfectly, it would be no better than the post-corrected HST. In other words, the HST fix made it "as good as new".
Theoretically, once you have perfect optics, and have corrected for the atmosphere perfectly (if you're on the ground), the sharpest image you can achieve is limited by quantum mechanics; it's known as the diffraction limit. The size of a diffraction-limited point source is inversely proportional to the diameter of the aperture (i.e., the primary mirror).
Since Paranal is a much larger telescope than HST, (8.2 meteres compared to 0.9), it's ideal, diffraction-limited image is much sharper than HST's. The fact that they can "only" get as good as HST shows you how hard adaptive optics is.
Re:Bug: Thinking of IT as Personal Property
on
This is IT?
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· Score: 2
They tried a yellow bike program in Santa Cruz, CA a couple of years ago. If you don't know Santa Cruz, it's pretty much Mecca for liberal ex-hippies. If a yellow bike program is going to work anywhere, it's going to work in Santa Cruz.
The program lasted about a week before all of the bikes disappeared. The problem with great ideas like this is that they assume that people aren't lazy, selfish buttheads...oops.
As I understand it, they designed the Toolset with Borland C++ Builder. They were expecting Borland to have a Linux version of this product (not Kylix), but it never materialized. However, the fact that they used BCB means a Mac version was never in the works...
I remember a stand-up comedy routine where the guy said that in order to ensure that First Contact goes smoothly, all Earth citizens should carry chewing gum at all times, in case they are the first to meet ET. That way a friendly encounter is assured:
Unfortunately, this is the only number in your post that means anything. The rest are pure speculation on your part.
"Most molecular biologists will tell you that even the most basic life is so complex that the odds of it forming from inanimate matter are staggeringly small, and we should count ourselves lucky that it managed to happen once in the entire history of the Universe"
This is simply untrue. In fact, any molecular biologists think it's possible that life may have formed from inanimate matter more than once on the Earth.
"Of course, you could simply throw those numbers out...but that wouldn't be very scientific."
Why would someone else's equally speculative take on the Drake Equation be any less "scientific" than yours?
"it's interesting to note that our entire (known) universe could be inside of a black hole."
Wow, groovy.
Except for the troubling lack of a singularity anywhere, and our complete failure to notice the tidal forces that should be ripping us all to shreds (how is that a "moot point"?)...
The software used by astronomers is also generally publicly available. For example, Debian Linux ships with IRAF, the image reduction software that most of us use (the ones who can't afford IDL anyway).
No, you missed the point that there are two kinds of black holes: Some are expired stars; the ones we can see have a normal star as a binary companion. Until now, these were always found to be between 3 and 7 solar masses. Others are "supermassive" black holes; we believe every galaxy has one of these at their center. These are typically more than a million solar masses.
They are both gravitational singularities, but on a hugely different scale, and the physics of their formation is totally different.
"How do we find stars and planets? We make assumptions about stellar phenomena and then predict other phenomena using those assumptions as long as they seem to work."
Huh? We find stars and planets by stepping outside at night and looking up. What exactly are the "stellar phenomena" that we have a long way to go before understanding?
I suppose, since you're questioning the mass determination of the black hole, you must be saying that we don't yet understand Kepler's 3rd law of motion (that is the only theory needed for the measurement). Hmm...Kepler came up with that in 1609. In 400 years, his laws have been used to: construct the first accurate mathematical model of the solar system (still in use today), predict a planet beyond Uranus (Neptune was discovered exactly where Keplerian physics said it had to be), send humans to the moon, send probes to the outer planets and beyond, and determine masses of binary stars throughout our galaxy.
In short, there's nothing in this particular measurement that requires *any* understanding of stellar physics. It's a simple application of 400-year old Newtonian gravity. If you want to question the result, I suggest looking at the systematic errors of the observations (e.g., is the inclination angle of the system known? if not, the black hole could be more massive than measured).
Oh, and the process you describe (start with an assumption, make a prediction based on the assumption, test prediction by experiment/observation, refine assumption) is called the scientific method, not "extrapolating data".
It's possible to extract huge amounts of energy by simply dropping matter into black holes. In fact, this is the most efficient way to get energy from matter. Too bad there aren't any nearby. Ah well, maybe we'll make one of our own someday.
OK, fair enough. These are good points, but the original post claimed that not having the root or user passwords was enough to foil the FBI, even if they had physical access to your machine. That's what I was questioning.
"The trick is that they have to know either my root or user passwords to install software that would have any chance of evading detection for more than the span of a single 'ps'."
Really? Assuming you have a floppy drive, why couldn't they load their own bare-bones Linux from floppies onto a RAM disk, and use that to mount your disks with root priveliges and install Magic Lantern that way?
No, the "here and now" factor is taken into account by the R_* term, which is the rate that stars form. Do the unit analysis: by multiplying that rate (N/year) by the average lifetime of a civilization (years) (along with all the other factors) you get the average number of active civilizations in our Galaxy, at any time, not the total number that have ever existed.
This also takes care of your other point regarding light travel time, because by definition, the average number of active civilizations in our galaxy is time-invariant.
"the Drake equation gives us NO new information about the statistics of life"
This is true, but it's not the point of the Drake equation. Frank Drake came up with it back before he founded SETI, as a way to speculate quantitatively about the possibility of life elsewhere. It's utility is that it separates the unknown factors regarding life in our Galaxy, so that the mind can deal with each independently. I mean, think about it:
Conversation about life in the universe, pre-Drake equation:
"How many civilizations do you think there are in our Galaxy?"
"I have no idea."
"Heavy."
"Yeah."
Same conversation, armed with DE:
"How many civilizations do you think there are in our Galaxy?"
"Who knows? But there are billions of stars, and I think about half probably have a planetary system of some kind."
"Yeah, but how many of those could support life? Even in our system, apparently only 1 of 9."
"OK, so let's go with that, for now. But how many of the life-bearing planets would evolve intelligent life?...."
and so on. The Drake Equation provides a framework for speculation about The Big Question: Is there intelligent life elsewhere in the universe?. It was whimsically conceived, and it was not meant to provide new information about the question.
"So why promote those freedoms (freedom to use, share, and modify)?
Because it would lead to a world filled with high performance, low cost software, right?"
This is more similar to the Open Source point-of-view than the Free Software position. Free Software promotes the Freedoms because the alternative (restricted, proprietary software) is morally wrong. Hence RMS's insistence that OSS != FS.
Slashdot Mirror
Right, that was my point. Since we can see this object (see image in article), it can't strictly be called dark matter. OK, that's pretty specious, but see my other posts in this thread for a longer explanation.
Executive Summary: we already knew objects like this existed, and we think we know how many there are in the milky way, so it can't really be part of the solution to the missing mass problem.
Pretty good point, but there's a big difference between a failed star (or brown dwarf) and a low-mass star like this object. We have a pretty good idea how many low-mass stars there are in the Galaxy, from the statistics of stars in our neighborhood. We already account for the presence of such objects when we compute the mass of known objects in our Galaxy. This object is in the "known" column of the Galactic Census; it isn't missing mass.
Now, if you want to discuss the uncertainty of the low-mass stellar mass function, and say that it's possible that there are lots more of these dim stars than we currently estimate, that's a different story (although no one would recommend making this argument based on the observation of a single object). However, there can't be so many of these little guys as to solve the missing mass problem.
"try reading"
OK. From the article:
"Observations of clusters of galaxies and
the large scale structure of individual galaxies tell us that no more than a quarter of the total amount of matter in the Universe consists of normal atoms and molecules that make up the familiar world around us."
IOW, at least 75 percent of the universe is made of something other than protons, neutrons and electrons. This dim star is in the 25 percent "normal matter" minority.
hope that helps!
We are already pretty sure that most of the missing matter must be non-baryonic (i.e., it must be made of something other than protons, neutrons and electrons).
The observed object is a dwarf star. It is luminous. This article should have been titled "Confirmation that one of the MACHO objects is not Dark Matter".
I mostly agree. I don't object to rich guys shelling out the dough for orbital joyrides (because, as others have pointed out, this should eventually drive costs down, and maybe someday I'll be a not-rich guy on an orbital joyride).
However, I think that if NASA is the one doing it, such commercialization would be a Bad Thing. Instead, it should be handled by private "space tourism" companies.
"The extra lense introduces a data loss. It will be removed in 2003"
Yeah, okay, no optic is perfect, but the loss caused by COSTAR is not significant.
Just FYI, while COSTAR won't be physically removed until 2003, it was permanently retracted out of the optical path a few weeks ago, in anticipation of the removal of the faint object spectrograph early next year (the last instrument that doesn't internally correct for Hubble's aberration).
cheers,
Jason
It's not a good analogy, because the correction used by Paranal is an adaptive optics system that continually updates the shape of the mirror 500 times per second to correct for the turbulent atmosphere, which causes images to bounce around in the focal plane (a/k/a the "twinkling" of stars). OTOH, the HST correction is static aberration correction, and therefore much simpler, technologically. HST doesn't need adaptive optics, because there is no atmosphere between it and its targets (that was the whole point of putting it in orbit).
Furthermore, even if the HST mirror had been manufactured perfectly, it would be no better than the post-corrected HST. In other words, the HST fix made it "as good as new".
Theoretically, once you have perfect optics, and have corrected for the atmosphere perfectly (if you're on the ground), the sharpest image you can achieve is limited by quantum mechanics; it's known as the diffraction limit. The size of a diffraction-limited point source is inversely proportional to the diameter of the aperture (i.e., the primary mirror).
Since Paranal is a much larger telescope than HST, (8.2 meteres compared to 0.9), it's ideal, diffraction-limited image is much sharper than HST's. The fact that they can "only" get as good as HST shows you how hard adaptive optics is.
They tried a yellow bike program in Santa Cruz, CA a couple of years ago. If you don't know Santa Cruz, it's pretty much Mecca for liberal ex-hippies. If a yellow bike program is going to work anywhere, it's going to work in Santa Cruz.
The program lasted about a week before all of the bikes disappeared. The problem with great ideas like this is that they assume that people aren't lazy, selfish buttheads...oops.
As I understand it, they designed the Toolset with Borland C++ Builder. They were expecting Borland to have a Linux version of this product (not Kylix), but it never materialized. However, the fact that they used BCB means a Mac version was never in the works...
"GPL for documentation (don't remember what it's called)"
Free Documentation License (FDL)
I remember a stand-up comedy routine where the guy said that in order to ensure that First Contact goes smoothly, all Earth citizens should carry chewing gum at all times, in case they are the first to meet ET. That way a friendly encounter is assured:
Alien: beep. beep.
Human: Want...some.....gum?
"1. 400 billion stars in the galaxy"
Unfortunately, this is the only number in your post that means anything. The rest are pure speculation on your part.
"Most molecular biologists will tell you that even the most basic life is so complex that the odds of it forming from inanimate matter are staggeringly small, and we should count ourselves lucky that it managed to happen once in the entire history of the Universe"
This is simply untrue. In fact, any molecular biologists think it's possible that life may have formed from inanimate matter more than once on the Earth.
"Of course, you could simply throw those numbers out...but that wouldn't be very scientific."
Why would someone else's equally speculative take on the Drake Equation be any less "scientific" than yours?
"it's interesting to note that our entire (known) universe could be inside of a black hole."
Wow, groovy.
Except for the troubling lack of a singularity anywhere, and our complete failure to notice the tidal forces that should be ripping us all to shreds (how is that a "moot point"?)...
Actually, most of the data used by astronomers is publicly available. Try the following:
HST data archive: every HST image. Also has other mission data.
Astronomical Data Center: archive of data tables published in peer-review astronomy journals
NASA/IPAC Extragalactic Database: index of known data for other galaxies. You can get redshifts here, for example.
The software used by astronomers is also generally publicly available. For example, Debian Linux ships with IRAF, the image reduction software that most of us use (the ones who can't afford IDL anyway).
No, you missed the point that there are two kinds of black holes: Some are expired stars; the ones we can see have a normal star as a binary companion. Until now, these were always found to be between 3 and 7 solar masses. Others are "supermassive" black holes; we believe every galaxy has one of these at their center. These are typically more than a million solar masses.
They are both gravitational singularities, but on a hugely different scale, and the physics of their formation is totally different.
"How do we find stars and planets? We make assumptions about stellar phenomena and then predict other phenomena using those assumptions as long as they seem to work."
Huh? We find stars and planets by stepping outside at night and looking up. What exactly are the "stellar phenomena" that we have a long way to go before understanding?
I suppose, since you're questioning the mass determination of the black hole, you must be saying that we don't yet understand Kepler's 3rd law of motion (that is the only theory needed for the measurement). Hmm...Kepler came up with that in 1609. In 400 years, his laws have been used to: construct the first accurate mathematical model of the solar system (still in use today), predict a planet beyond Uranus (Neptune was discovered exactly where Keplerian physics said it had to be), send humans to the moon, send probes to the outer planets and beyond, and determine masses of binary stars throughout our galaxy.
In short, there's nothing in this particular measurement that requires *any* understanding of stellar physics. It's a simple application of 400-year old Newtonian gravity. If you want to question the result, I suggest looking at the systematic errors of the observations (e.g., is the inclination angle of the system known? if not, the black hole could be more massive than measured).
Oh, and the process you describe (start with an assumption, make a prediction based on the assumption, test prediction by experiment/observation, refine assumption) is called the scientific method, not "extrapolating data".
It's possible to extract huge amounts of energy by simply dropping matter into black holes. In fact, this is the most efficient way to get energy from matter. Too bad there aren't any nearby. Ah well, maybe we'll make one of our own someday.
You have to use "& lt;" and "& gt;" (without spaces) for the left and right angle brackets :)
:p)
(note I didn't put that statement in a <fact> tag, so you can't sue if it doesn't work
How about a new tag for HTML/UBB/whatever:
<fact>Linux rules, M$ drools!</fact>
This tag would lend the enclosed text more credence, but also hold the poster responsible for its content.
heh.
OK, fair enough. These are good points, but the original post claimed that not having the root or user passwords was enough to foil the FBI, even if they had physical access to your machine. That's what I was questioning.
"The trick is that they have to know either my root or user passwords to install software that would have any chance of evading detection for more than the span of a single 'ps'."
Really? Assuming you have a floppy drive, why couldn't they load their own bare-bones Linux from floppies onto a RAM disk, and use that to mount your disks with root priveliges and install Magic Lantern that way?
This isn't rhetorical, I'm really asking...
No, the "here and now" factor is taken into account by the R_* term, which is the rate that stars form. Do the unit analysis: by multiplying that rate (N/year) by the average lifetime of a civilization (years) (along with all the other factors) you get the average number of active civilizations in our Galaxy, at any time, not the total number that have ever existed.
This also takes care of your other point regarding light travel time, because by definition, the average number of active civilizations in our galaxy is time-invariant.
"the Drake equation gives us NO new information about the statistics of life"
This is true, but it's not the point of the Drake equation. Frank Drake came up with it back before he founded SETI, as a way to speculate quantitatively about the possibility of life elsewhere. It's utility is that it separates the unknown factors regarding life in our Galaxy, so that the mind can deal with each independently. I mean, think about it:
Conversation about life in the universe, pre-Drake equation:
"How many civilizations do you think there are in our Galaxy?"
"I have no idea."
"Heavy."
"Yeah."
Same conversation, armed with DE:
"How many civilizations do you think there are in our Galaxy?"
"Who knows? But there are billions of stars, and I think about half probably have a planetary system of some kind."
"Yeah, but how many of those could support life? Even in our system, apparently only 1 of 9."
"OK, so let's go with that, for now. But how many of the life-bearing planets would evolve intelligent life?...."
and so on. The Drake Equation provides a framework for speculation about The Big Question: Is there intelligent life elsewhere in the universe?. It was whimsically conceived, and it was not meant to provide new information about the question.
"So why promote those freedoms (freedom to use, share, and modify)?
Because it would lead to a world filled with high performance, low cost software, right?"
This is more similar to the Open Source point-of-view than the Free Software position. Free Software promotes the Freedoms because the alternative (restricted, proprietary software) is morally wrong. Hence RMS's insistence that OSS != FS.