Liquid mirrors are ingenious and have many benefits over solid mirrors.
... But one killer disadvantage: they only point straight up. Generally, astronomers want to look at what they want to look at, not just whatever is overhead at the moment. (There are some exceptions: for some cosmological surveys, any patch of sky will do).
This issue has been covered before in the documentary The Corporation.
If I recall correctly, they argue that if corporations were analyzed as if they were individuals by psychiatrists, they would be classified as psychopaths.
There is an interesting film called "The Corporation" that argues that if corporations were individuals they would be diagnosed as psychopathic, primarily because their sole motive is shareholder profit.
Two elderly women are at a Catskill mountain resort, and one of 'em says, "Boy, the food at this place is really terrible." The other one says, "Yeah, I know; and such small portions." Woody Allen
This MS product does indeed sound very similar to Google Sky.
I think the difference between both of these and e.g. Stellarium/Celestia is the database that sits behind them. Usually "planetarium" software consists of a bunch of points for stars, with perhaps a few objects represented by pixels. You can upload images but you have to do it yourself.
In contrast, Google Sky (and presumably the MS telescope) show you pixels from large databases such as the Sloan Digital Sky Survey. The latter covers roughly 1/4 of the whole sky.
Google is heavily involved with the LSST project. MS has been involved in the Sloan Digital Sky Survey for quite some time via the late Jim Gray. Its great for astronomy that both of these companies are competing in an area with little prospects for "monetization".
I particularly like the idea
Imaging nearby Earth-sized worlds using large telescopes with multiple instruments and separate spacecraft to block the light from these exoplanets' host star (Webster Cash, University of Colorado, Boulder; David Spergel, Princeton University, N.J.). This seems very cool - the idea is that you put a big screen out in space to block the light of the host star, but not that of the star's planet. This is not a new idea - the problem is diffraction around the screen (occulter). But it looks like Cash and Spergel have found a design that minimizes the diffraction.
But the same people (presumably) have also rushed off to edit Wikipedia! (I see a half dozen edits this morning, to add in the "new" thickness.) That's the part that I find incredible. And people really take Wikipedia seriously?
And in doing so, the article has been clarified as to what "thickness" means, as well as updated it with the new information. None of the "wild speculation" on this thread is on the article, so I'm not sure that's relevant.
The wild speculation is possibly triggered here. In itself, this statement is accurate: the distribution of stars in Milky Way is thicker in the center, due to a component known as the bulge. But the measurement cited in the Press Release is of the gas, and, as far as I can tell, this measurement is not of the center but, since it is based on pulsars, is likely to be near the Sun's position which is around 20,000 light years in the disk away from the center.
Nevertheless the wikipedia article (my emphasis) states:
with the center bulge's thickness recently discovered by University of Sydney researchers to be about 12,000 light years, contrary to the previously thought 6,000.[9]
This is not clarification, but rather complete confusion! Nowhere does the press release make any comments about the bulge.
It would be good to have a clearer article to explain different measurements for "thickness", but that doesn't make the article wrong, when it is based on sources.
I have argued that article is wrong. "Quoting sources" doesn't help if the quoter does not understand the source.
... why don't you become an editor and help it along? It's not hard at all...
I agree that its not hard to do, but it's a non-negligible amount of effort to do well. Nevertheless, I would be willing to do so for a few subjects of interest, except for one problem: someone else might change the article in a negative way. This could be intentional vandalism, or, more likely, simply well-intentioned, but sloppy, edits of the type discussed above.
Now you will say that I could always revert the changes... but that means that not only would I have to write the article, but constantly "maintain" and "protect" it as well. It's the latter prospect that is discouraging.
On the other hand, if I were contacted by an editor to write for a "real/classical" encyclopedia, I could be assured that my hard work would be protected.
God forbid some stupid fucking amateurs should be so passionately interested in your field that they would do something so counterproductive to your ivory-tower efforts as... editing a Wikipedia article
I guess I should clarify. I have no problem with amateurs editing Wikipedia. But I do have problems with, as you say, stupid, fucking amateurs editing Wikipedia.
For example, at the moment Wikipedia says:
The disk of the Milky Way galaxy is approximately 100,000 light years in diameter, and is believed to be about 1,000 light years thick (average thickness),[8] with the center bulge's thickness recently discovered by University of Sydney researchers to be about 12,000 light years, contrary to the previously thought 6,000.[9]
This is not correct. The Wikipedia editors have decided somehow that the 12,000 light year measurement refers to the center of the Milky Way (even though it does not state this anywhere in the U Sydney Press Release). As I said above, the 12,000 light year measurement refers not to a location but to a component, the Warm Ionised Medium or WIM.
My point is simply that the quality of Wikipedia is only as good as the effort that editors make to understand a subject and edit appropriately.
... is shown right here on this slashdot discussion.
I am an astronomer, so first some background: The Milky way has several components: young stars, old stars, dust and various components of gas. They all have different thicknesses. There is no single "thickness". One of these components (warm ionized gas) has been measured to have a thickness larger than expected. This measurement has not been confirmed by others, nor (I think) published yet.
Despite this complexity, this discussion thread is awash with arguments, confusion, wild speculation, suggestions that dark matter might be wrong etc. etc. OK, fine, this is slashdot, that's what slashdot is for.
But the same people (presumably) have also rushed off to edit Wikipedia! (I see a half dozen edits this morning, to add in the "new" thickness.) That's the part that I find incredible. And people really take Wikipedia seriously?
... but I would call this simply "bad" science - You can't use one poorly-understood phenomenon to explore another. You are incorrect. Gravitational waves (the phenomenon) are a very clear and very well understood prediction of the theory of General Relativity. So I would say that this is as far from "bad" science as you can get.
If, ultimately, gravitational waves are not detected by LIGO and its successors that would prove GR was incorrect. And that would be a huge scientific advance.
When people actually intentionally buy a next generation media player, they overwhelmingly chose HD-DVD.
Overwhelming?
According to this article, an HD-DVD rep said "HD DVD players represented 49.3 per cent of the players for high definition discs sold as of Dec. 22, quoting figures from market research firm NPD." (Excluding PS3).
Would there be any chance of a small asteroid (one that could cause some problems) currently heading for earth not be detected yet by scientists? It is impossible for astronomers to chart, track or project the trajectories of the billions of space rocks left over from the formation of the Solar System. It is impossible to find and track all of the rocks, but with next-generation surveys, such as Pan-STARRS and LSST, it should possible to get most of the big ones.
There is a lot more to creating a good and accurate entry than simply linking facts to sources.
More important is the overall picture presented of complex phenomena: which facts are included, which are downplayed, and which are omitted entirely. I'm an astrophysics prof, and while I do use Wikipedia myself occasionally, I have also seen some very bad or misleading articles (this is in areas where I have expertise). So I advise my students to use it with extreme caution. It's OK starting point for further research, but it shouldn't be their first and last stop.
(In principle, I would be happy to contribute specialist-level articles myself, but it's a fair bit of work, and I am not keen that someone else (who has a lot less expertise) could overwrite my contribution.)
What is your privacy policy? And what kind of data is sent over email? If your sending students' personal details etc around you might not have their permission to send/store them off-campus on equipment not owned by the college.
Exactly.
Did anyone notice the irony that the previous slashdot article is titled
Google Gives Up IP of Anonymous Blogger
The GZK cutoff applies only for cosmic rays travelling distances grater than 100 Mpc or so... these AGN believed to be responsible for the highest energy events are within this distance
That's because "on the sky" that's the way it is! Suppose you are in the Northern hemisphere looking at the southern horizon. North is up, but east is left not right.
Halton Arp's idea that "many high-energy, high-redshift quasars appear to be located in close proximity to, and interacting with, low-redshift, low-energy galaxies" has been proven incorrect.
1) Its impossible to explain quasar absorption lines, which must be due to foreground objects
Unfortunately, Arp and few others conveniently ignore the irrefutable evidence against their ideas. Luckily the rest of the astrophysical community understands scientific evidence. That's the reason that no one pays attention to Arp and colleagues.
Equally unfortunately there is always a group of people (especially on Slashdot) quick to embrace the romantic notion of the outsider "kicked off the telescope for his heretical views". After all, in the movies that's the guy that turns out to be right in the end...
... Until we have some of this stuff isolated in a laboratory, it only exists as a mathematic abstract.
... Let's quit all this deep-space navel-gazing and isolate some dark matter. Where's the oil-drop experiment of the new millenium?
I find it interesting that some people think that something isn't "real" unless it is seen in the lab.
Dark matter likely interacts only through the weak force and gravity, much like the neutrino.
Neutrinos cannot be "isolated" - but their existence can be detected indirectly through their (rare) interactions with other particles in detectors. That's perfectly valid, but why is it somehow more "real" than detecting a particle through its gravitational interactions?
Slashdot Mirror
Liquid mirrors are ingenious and have many benefits over solid mirrors.
... But one killer disadvantage: they only point straight up. Generally, astronomers want to look at what they want to look at, not just whatever is overhead at the moment. (There are some exceptions: for some cosmological surveys, any patch of sky will do).
This is the main reason they are not widely used.
This issue has been covered before in the documentary The Corporation.
If I recall correctly, they argue that if corporations were analyzed as if they were individuals by psychiatrists, they would be classified as psychopaths.
No, you're not cynical. You are bang on.
There is an interesting film called "The Corporation" that argues that if corporations were individuals they would be diagnosed as psychopathic, primarily because their sole motive is shareholder profit.
... can be found here. I never did get through that sulky door. Now I can relive the aggravation all over again.
Mod Parent Up. He/She knows what they are talking about (far more than the grandparent).
I would only add that, since black holes are made from collapsed stars, they are baryonic. Hence the dark matter cannot be black holes.
My guess is that that imagery is from IRAS which did not complete its sky survey due to failure of some components.
This MS product does indeed sound very similar to Google Sky.
I think the difference between both of these and e.g. Stellarium/Celestia is the database that sits behind them. Usually "planetarium" software consists of a bunch of points for stars, with perhaps a few objects represented by pixels. You can upload images but you have to do it yourself.
In contrast, Google Sky (and presumably the MS telescope) show you pixels from large databases such as the Sloan Digital Sky Survey. The latter covers roughly 1/4 of the whole sky.
Google is heavily involved with the LSST project.
MS has been involved in the Sloan Digital Sky Survey for quite some time via the late Jim Gray.
Its great for astronomy that both of these companies are competing in an area with little prospects for "monetization".
I particularly like the idea Imaging nearby Earth-sized worlds using large telescopes with multiple instruments and separate spacecraft to block the light from these exoplanets' host star (Webster Cash, University of Colorado, Boulder; David Spergel, Princeton University, N.J.). This seems very cool - the idea is that you put a big screen out in space to block the light of the host star, but not that of the star's planet. This is not a new idea - the problem is diffraction around the screen (occulter). But it looks like Cash and Spergel have found a design that minimizes the diffraction.
And in doing so, the article has been clarified as to what "thickness" means, as well as updated it with the new information. None of the "wild speculation" on this thread is on the article, so I'm not sure that's relevant.
The wild speculation is possibly triggered here. In itself, this statement is accurate: the distribution of stars in Milky Way is thicker in the center, due to a component known as the bulge. But the measurement cited in the Press Release is of the gas, and, as far as I can tell, this measurement is not of the center but, since it is based on pulsars, is likely to be near the Sun's position which is around 20,000 light years in the disk away from the center.
Nevertheless the wikipedia article (my emphasis) states:
with the center bulge's thickness recently discovered by University of Sydney researchers to be about 12,000 light years, contrary to the previously thought 6,000.[9]This is not clarification, but rather complete confusion! Nowhere does the press release make any comments about the bulge.
It would be good to have a clearer article to explain different measurements for "thickness", but that doesn't make the article wrong, when it is based on sources.I have argued that article is wrong. "Quoting sources" doesn't help if the quoter does not understand the source.
... why don't you become an editor and help it along? It's not hard at allI agree that its not hard to do, but it's a non-negligible amount of effort to do well. Nevertheless, I would be willing to do so for a few subjects of interest, except for one problem: someone else might change the article in a negative way. This could be intentional vandalism, or, more likely, simply well-intentioned, but sloppy, edits of the type discussed above.
Now you will say that I could always revert the changes ... but that means that not only would I have to write the article, but constantly "maintain" and "protect" it as well. It's the latter prospect that is discouraging.
On the other hand, if I were contacted by an editor to write for a "real/classical" encyclopedia, I could be assured that my hard work would be protected.
I guess I should clarify. I have no problem with amateurs editing Wikipedia. But I do have problems with, as you say, stupid, fucking amateurs editing Wikipedia.
For example, at the moment Wikipedia says:
The disk of the Milky Way galaxy is approximately 100,000 light years in diameter, and is believed to be about 1,000 light years thick (average thickness),[8] with the center bulge's thickness recently discovered by University of Sydney researchers to be about 12,000 light years, contrary to the previously thought 6,000.[9]This is not correct. The Wikipedia editors have decided somehow that the 12,000 light year measurement refers to the center of the Milky Way (even though it does not state this anywhere in the U Sydney Press Release). As I said above, the 12,000 light year measurement refers not to a location but to a component, the Warm Ionised Medium or WIM.
My point is simply that the quality of Wikipedia is only as good as the effort that editors make to understand a subject and edit appropriately.
I am an astronomer, so first some background: The Milky way has several components: young stars, old stars, dust and various components of gas. They all have different thicknesses. There is no single "thickness". One of these components (warm ionized gas) has been measured to have a thickness larger than expected. This measurement has not been confirmed by others, nor (I think) published yet.
Despite this complexity, this discussion thread is awash with arguments, confusion, wild speculation, suggestions that dark matter might be wrong etc. etc. OK, fine, this is slashdot, that's what slashdot is for.
But the same people (presumably) have also rushed off to edit Wikipedia! (I see a half dozen edits this morning, to add in the "new" thickness.) That's the part that I find incredible. And people really take Wikipedia seriously?
... but I would call this simply "bad" science - You can't use one poorly-understood phenomenon to explore another. You are incorrect. Gravitational waves (the phenomenon) are a very clear and very well understood prediction of the theory of General Relativity. So I would say that this is as far from "bad" science as you can get. If, ultimately, gravitational waves are not detected by LIGO and its successors that would prove GR was incorrect. And that would be a huge scientific advance.Overwhelming?
According to this article, an HD-DVD rep said "HD DVD players represented 49.3 per cent of the players for high definition discs sold as of Dec. 22, quoting figures from market research firm NPD." (Excluding PS3).
IAAAP: The explosion model was ruled out in the late 1980's. Why? velocities of galaxies are not compatible with observations.
It is impossible to find and track all of the rocks, but with next-generation surveys, such as Pan-STARRS and LSST, it should possible to get most of the big ones.
There is a lot more to creating a good and accurate entry than simply linking facts to sources.
More important is the overall picture presented of complex phenomena: which facts are included, which are downplayed, and which are omitted entirely. I'm an astrophysics prof, and while I do use Wikipedia myself occasionally, I have also seen some very bad or misleading articles (this is in areas where I have expertise). So I advise my students to use it with extreme caution. It's OK starting point for further research, but it shouldn't be their first and last stop.
(In principle, I would be happy to contribute specialist-level articles myself, but it's a fair bit of work, and I am not keen that someone else (who has a lot less expertise) could overwrite my contribution.)
The GZK cutoff applies only for cosmic rays travelling distances grater than 100 Mpc or so ... these AGN believed to be responsible for the highest energy events are within this distance
399 CDN = 398.36 USD today, according to this conversion tool
That's because "on the sky" that's the way it is! Suppose you are in the Northern hemisphere looking at the southern horizon. North is up, but east is left not right.
Halton Arp's idea that "many high-energy, high-redshift quasars appear to be located in close proximity to, and interacting with, low-redshift, low-energy galaxies" has been proven incorrect.
1) Its impossible to explain quasar absorption lines, which must be due to foreground objects
2) Magification due to gravitational lensing by foreground galaxies neatly explains any excess of quasars near galaxies as seen on the sky and requires them to be at high redshift. See e.g. Detection of Cosmic Magnification with the Sloan Digital Sky Survey
Unfortunately, Arp and few others conveniently ignore the irrefutable evidence against their ideas. Luckily the rest of the astrophysical community understands scientific evidence. That's the reason that no one pays attention to Arp and colleagues.
Equally unfortunately there is always a group of people (especially on Slashdot) quick to embrace the romantic notion of the outsider "kicked off the telescope for his heretical views". After all, in the movies that's the guy that turns out to be right in the end ...
... Until we have some of this stuff isolated in a laboratory, it only exists as a mathematic abstract.
... Let's quit all this deep-space navel-gazing and isolate some dark matter. Where's the oil-drop experiment of the new millenium?
I find it interesting that some people think that something isn't "real" unless it is seen in the lab.
Dark matter likely interacts only through the weak force and gravity, much like the neutrino.
Neutrinos cannot be "isolated" - but their existence can be detected indirectly through their (rare) interactions with other particles in detectors. That's perfectly valid, but why is it somehow more "real" than detecting a particle through its gravitational interactions?
I think this link is not to the right movies. These links are associated with papers submitted in 2004, not 2007.