You're happy your iPod was stolen? And happy that you have to waste another 300+ bucks on a player that probably is just a rumor? All the power to you, but get a brain... seriously..
Cute, but your reply is constructed in a merely syntactic way. My criterion is not arbitrary. It's my own opinion, thought out, maybe worthy of discussion, and possibly wrong. But not arbitrary. We all have a varying set of criteria by which we judge others' actions to be indicative of a mature person --- these are chosen for one reason or another because they have some personal bearing on the judgement; they are typically not plucked in a Monte-Carlo arbitrary fashion from the domain of all possible criteria.
But I'll agree that your.sig is catchy, however inaccurate.
I vote for the one person who understands my life, knows what my needs are, and can adjust the law to be realistic, moral and promote freedom not restrict it.
That person is me. I recommend voting for yourself on every ballot, straight ticket, every position. Vote NO to all referenda and judge retentions. Write yourself in and you'll be voting for the only person able to enforce the law the way you want it enforced.
Wow. That sounds pathological. A mark of a mature person is one who can see the benefit of voting against his own self-interest for the benefit of others. Can you even imagine such a thing?
As an astronomy educator, believe me, I understand. But in realizing that scientific theories are really only our best models right now, it's actually invigorating that the more we study and investigate the universe the more beautiful, complex, and subtle it is.
It's probable that *everything* you have been taught will some day have to be "unlearned". In this case, as with many others, it's not so much that what you were taught was wrong, only that it was imprecise. The article reaffirms that it is still true that most of the bright stars in the sky are members of multiple-star systems. Just the previously unobserved swarm of very dim, red stars seem to be largely isolated. Still consistent with previous observations.
In case the AC isn't modded up, he/she is correct, the above linked article has been seriously rebutted and is now of dubious worth. The puzzle remains.
You know, it seems that dark matter news items call out the conspiracy theorists and sarcastic armchair physicists just as evolution/creation stories do. There is a post above regarding dark matter as some government-funded fantasy story, with the implication that we astrophysicsts know it to be bogus but thanks for the cash anyway.
Now the parent post, with a typically simplistic, erroneous, and (usually) creationist take on cosmology.
No, the redshift observed from distant galaxies is not due to the Doppler effect, but to the expansion of space itself. It is a subtle and important distinction. There is not the slightest evidence that any constant of nature identified above has changed, and in fact we can put rather stringent limits on any (as of yet) imperceptible change because of the details of the spectra of these distant objects. What is the proposed physics of these "properties of space"? Why would they affect the speed of light but not any other details of the radiation passing through? If the speed of light has indeed changed, so as to make the Universe younger than we presently think, then what is the explanation for the ages of the oldest globular clusters, which fit in nicely with the current derived age? You would need to modify our understanding of stellar evolution (and radioactive decay), which are 2 independent methods used to date the clusters, since we shouldn't have clusters older than the universe.
And anyway, the brand of dark matter in the article is not cosmological, but is proposed to account for the anomalous velocities of stars orbiting the centers of galaxies. This is not the "dark energy" that you may have confused it with.
Well, I commented on this elsewhere, but is this really true in general? I'd suspect that it really comes down to how much time is spent compiling each file as compared to reading it (and writing it) from the disk. For these C++ files, it takes on the order of seconds to compile each, much longer than any disk read/write time.
That might be true, but I'm sure the computer spends much more time (on the order of seconds per file) compiling each file than reading it from the disk (tenths to hundredths of a second). In any case, I was a little hasty ascribing the multi-thready behavior to gcc. It's probably the makefile Qt generated that distributes the load, or perhaps the OS itself. I'm not sure --- I just liked seeing the stats for both processors hit 90%.
Yep. I have an older 1GHz G4 PowerBook and just received the iMac 2.0 GHz dual-core. I compiled Qt 4.1 for both, and *roughly* (I wasn't paying exact attention to the clock) the iMac compiled the entire library (identical configure options) about 7 times faster than the single G4. About what I'd expect. For my shorter jobs it's also about 6-7x faster. The compiler (gcc) utilizes both cores nicely, as I can see with the system load monitor.
Black holes are usually one of the first culprits cited for any observed anomaly. We can see from the orbital speed distribution that the distribution of "dark matter" is roughly spherical. We can plausibly rule out black holes as the major component of this mass by noting many fewer gravitatational lensing events than would be needed if the hypothesis were true. This is also how we rule out brown dwarfs and jupiter-sized objects as well --- not enough observed "micro-lensing" events. Not to mention that one would have a hard time postulating how all those black holes got there, and why they're so quiet in the X-ray spectrum.
Titanium PowerBook (upgraded to 1GB) serving as my only machine for work and home (6-10 hrs use every day) for 3 years, many trips, no issues. Probably it helps that I use a Happy Hacking keyboard 90% of the time (work and home) to prolong keyboard life, but I'm impressed with how easy it is to commute with daily and use as my only software development / writing / music server / home computer. Will definitely buy another, eventually.
These are remarkable and strong statements for the judge to make, and you might suppose that he'd back them up in his decision. All the answers are there:
Thanks --- color me fooled. Thought that it was directly related to the W3C. Anyway, I *did* learn some rudimentary CSS from it, though only for basic tag syntax. I learned the most about layout from studying examples. I didn't think anything was odd since I don't use VB, but thanks for the notice.
I was in your shoes, too --- just a smattering of HTML. I needed to create pages for my students and local sailing association, so I availed myself of Web Schools from W3C, which is pretty straight from the horses mouth, but no tricks or advanced techniques, and then studying layout like CSS Zen Garden and Boxes Tutorials. I tried to go XHTML 1.0 Strict, and validated my pages with the W3C validator, which gave useful feedback. (Don't look at my "home" page indicated by my ID --- it's just a stub). You're welcome to look at my amateurish example at my school home page. Good luck.
It would seem that an obvious strategy for them would be to archive tv shows and then serve them up over the internet. We wouldn't need DVRs then --- just tv a la carte.
Re:Watch a little more closely ...
on
Deep in the Core
·
· Score: 1
The links are a little opaque (joke) to me. What are the distinctions between the standard astrophysical models and the models including "correct" plasma dynamics? Are you certain that those doing the modeling are truly ignorant of plasma dynamics? Could it be that these effects have been considered and rejected for some reason, e.g. that the regime in question was far too low in density? I worked with astrophysicists doing numerical 3D hydro models of supernova explosions; believe me, they were very well versed in their field, and they would absolutely kill for a competitive edge over colleagues if they thought for a minute they were missing something obvious. I'm not too familiar with Eta Carinae models, though I have a passing familiarity with the object itself --- not my field. What "stuff" happens? And what does all this have to do with cosmology?
Re:Watch a little more closely ...
on
Deep in the Core
·
· Score: 1
I'm sorry, I should have been clearer. We see galaxies whose redshift suggests (according to the standard interpretation) that they're 12 billion light years away, and thus formed in the first billion years after presumed recombination, made of stars that had to be 4 billion years old at the time. I.e., 12+4 > 13.7.
Why do the stars have to be 4 billion years old at the time? Sorry, this isn't at all obvious to me.
That's to your credit. Most astrophysicists would prefer to pretend that, e.g., quantized redshift as referenced to the CMB rest-frame in low-redshift galaxies, or to angularly-nearby low-redshift galaxies in the case of high-redshift galaxies and quasars, don't exist. Most would prefer to pretend that high-redshift quasars (e.g. z=2.11) physically in front of low-redshift opaque galaxies (e.g. NGC 7319, z=0.0225) don't exist.
Well, I know a lot of astrophysicists, and pretending doesn't really have anything to do with it. Your examples are not particularly bothersome because, as is pointed out by another, there are other explanations for these anomalies. Additionally, there is enormous and compelling evidence that our interpretations of redshift and lookback time are robust.
I also never took a "plasma" class, only those standard classes in EM, Thermo, Stat Mech. What is the claim of the engineers? Where are we ignorant?
Re:Watch a little more closely ...
on
Deep in the Core
·
· Score: 1
What? I don't understand your objection. Are you talking about those galaxies that we see as they were 12 billion years ago, or close galaxies 12 billion years old? And what do 4 billion year old stars have to do with it? As an astrophysicist, I'd like to be an apologetic for the standard cosmological model, but I don't understand your problem with it.
We can place an upper limit on the *number* of objects that may compose a massive halo by carefully observing "microlensing" events --- tiny fluctuations in the brightness of distant halo stars due to matter passing in front of them. Many of these events have been observed, but not enough to account for the mass responsible for the so-called anomalous galactic rotation curves. We then think that perhaps there are a lesser number of more massive objects, or something else we haven't thought of yet. In any case, the standard Big Bang model predicts an upper limit on the amount of baryonic matter ("regular" matter, protons/neutrons) in the Universe, so if the massive galactic halos exist, they should still fall under this limit, or there'll be trouble.
Hi --- I'll give a shot at answering (I'm an astrophysicist, if that matters)
I'm not quite sure what you mean by "Dark Matter is far from an accepted Hypothesis". It is certainly not far-fetched to imagine that there is some quantity of matter, perhaps substantial, that does not "glow" like stars do. This is why it is "dark". The original problem was one of galactic rotation curves --- matter in the outskirts of galaxies rotated around the center in a fashion exactly mimicing what it would do if there was a spherical distribution of matter extending beyond the glow of the visible disk. The hypothesis that there was just such a distribution that we cannot see is not so far-fetched. It has been admittedly difficult to identify the "conventional" bodies that could be responsible for the lion's share of such a halo. Upper limits on the numbers of brown dwarfs, Jupiter-sized objects, and small black holes have shown that no one of these are primarily responsible. Still the search continues, as it would in any good scientific theory. Any of these possibilities are seen as a simpler approach than modifying our most basic models of gravitational behavior, especially when there is no similar pattern of deviation from known laws on different scales. And, as shown by the follow-up paper in the archives, there is a real possibility that the authors have made an honest mistake.
No, no one has really answered my question. My problem is that I have some understanding of relativity, so I know that any explination involving two objects moving apart at greater than the speed of light is bunk.
But it is not "bunk"; it is reality. I see you have some understanding of relativity, but I'm suggesting that your understanding is incomplete. I'm not picking on you, but there is a subtle issue at stake. When you say "moving apart", you have to be careful in assigning coordinates to those objects. Objects cannot move relative to a set of coordinates faster than the speed of light, but there is no such restriction on how fast the coordinates themselves can expand.
As far as coordinate systems go sure you can set them to change in any way you like, but it is also useless to have them change at a rate greater than c.
No, not useless. In fact it is a prediction of general relativity and most cosmological models, and borne out by simple explanations such as the cosmological redshift, which is not really a Doppler shift at all, but a consequence of the expansion of space-time itself.
Hi,
I don't know if anyone has answered this to your satisfaction yet, but there is a distinction between relative velocities and coordinate velocities. Relative velocities, as described by special relativity, involve measurements of coordinate differences. In general relativity (cosmology, here) there is no restriction upon the rate at which the coordinates themselves (used to describe positions and velocities) can change. As the universe expands, it is the coordinates that change faster than the speed of light, though any local measurements of these coordinates is bound by relativity. It is easiest to think of the galaxies as fairly stationary in space, but carried along by universal expansion. There is no limit to the rate of coordinate expansion.
Slashdot Mirror
...and I just ran out of mod points. Nice.
Ok, thanks for the advice! I'll look into it!
Well, mine was just stolen! Yahoo! Now I can upgrade!
George Deutsch? Is that you? I think you're looking for Monster.com. HTH. HAND.
But I'll agree that your .sig is catchy, however inaccurate.
That person is me. I recommend voting for yourself on every ballot, straight ticket, every position. Vote NO to all referenda and judge retentions. Write yourself in and you'll be voting for the only person able to enforce the law the way you want it enforced.
Wow. That sounds pathological. A mark of a mature person is one who can see the benefit of voting against his own self-interest for the benefit of others. Can you even imagine such a thing?
It's probable that *everything* you have been taught will some day have to be "unlearned". In this case, as with many others, it's not so much that what you were taught was wrong, only that it was imprecise. The article reaffirms that it is still true that most of the bright stars in the sky are members of multiple-star systems. Just the previously unobserved swarm of very dim, red stars seem to be largely isolated. Still consistent with previous observations.
In case the AC isn't modded up, he/she is correct, the above linked article has been seriously rebutted and is now of dubious worth. The puzzle remains.
Now the parent post, with a typically simplistic, erroneous, and (usually) creationist take on cosmology.
No, the redshift observed from distant galaxies is not due to the Doppler effect, but to the expansion of space itself. It is a subtle and important distinction. There is not the slightest evidence that any constant of nature identified above has changed, and in fact we can put rather stringent limits on any (as of yet) imperceptible change because of the details of the spectra of these distant objects. What is the proposed physics of these "properties of space"? Why would they affect the speed of light but not any other details of the radiation passing through? If the speed of light has indeed changed, so as to make the Universe younger than we presently think, then what is the explanation for the ages of the oldest globular clusters, which fit in nicely with the current derived age? You would need to modify our understanding of stellar evolution (and radioactive decay), which are 2 independent methods used to date the clusters, since we shouldn't have clusters older than the universe.
And anyway, the brand of dark matter in the article is not cosmological, but is proposed to account for the anomalous velocities of stars orbiting the centers of galaxies. This is not the "dark energy" that you may have confused it with.
Well, I commented on this elsewhere, but is this really true in general? I'd suspect that it really comes down to how much time is spent compiling each file as compared to reading it (and writing it) from the disk. For these C++ files, it takes on the order of seconds to compile each, much longer than any disk read/write time.
That might be true, but I'm sure the computer spends much more time (on the order of seconds per file) compiling each file than reading it from the disk (tenths to hundredths of a second). In any case, I was a little hasty ascribing the multi-thready behavior to gcc. It's probably the makefile Qt generated that distributes the load, or perhaps the OS itself. I'm not sure --- I just liked seeing the stats for both processors hit 90%.
Yep. I have an older 1GHz G4 PowerBook and just received the iMac 2.0 GHz dual-core. I compiled Qt 4.1 for both, and *roughly* (I wasn't paying exact attention to the clock) the iMac compiled the entire library (identical configure options) about 7 times faster than the single G4. About what I'd expect. For my shorter jobs it's also about 6-7x faster. The compiler (gcc) utilizes both cores nicely, as I can see with the system load monitor.
Black holes are usually one of the first culprits cited for any observed anomaly. We can see from the orbital speed distribution that the distribution of "dark matter" is roughly spherical. We can plausibly rule out black holes as the major component of this mass by noting many fewer gravitatational lensing events than would be needed if the hypothesis were true. This is also how we rule out brown dwarfs and jupiter-sized objects as well --- not enough observed "micro-lensing" events. Not to mention that one would have a hard time postulating how all those black holes got there, and why they're so quiet in the X-ray spectrum.
Titanium PowerBook (upgraded to 1GB) serving as my only machine for work and home (6-10 hrs use every day) for 3 years, many trips, no issues. Probably it helps that I use a Happy Hacking keyboard 90% of the time (work and home) to prolong keyboard life, but I'm impressed with how easy it is to commute with daily and use as my only software development / writing / music server / home computer. Will definitely buy another, eventually.
Judge's Decision
It's a great read.
Thanks --- color me fooled. Thought that it was directly related to the W3C. Anyway, I *did* learn some rudimentary CSS from it, though only for basic tag syntax. I learned the most about layout from studying examples. I didn't think anything was odd since I don't use VB, but thanks for the notice.
I was in your shoes, too --- just a smattering of HTML. I needed to create pages for my students and local sailing association, so I availed myself of Web Schools from W3C, which is pretty straight from the horses mouth, but no tricks or advanced techniques, and then studying layout like CSS Zen Garden and Boxes Tutorials. I tried to go XHTML 1.0 Strict, and validated my pages with the W3C validator, which gave useful feedback. (Don't look at my "home" page indicated by my ID --- it's just a stub). You're welcome to look at my amateurish example at my school home page. Good luck.
It would seem that an obvious strategy for them would be to archive tv shows and then serve them up over the internet. We wouldn't need DVRs then --- just tv a la carte.
The links are a little opaque (joke) to me. What are the distinctions between the standard astrophysical models and the models including "correct" plasma dynamics? Are you certain that those doing the modeling are truly ignorant of plasma dynamics? Could it be that these effects have been considered and rejected for some reason, e.g. that the regime in question was far too low in density? I worked with astrophysicists doing numerical 3D hydro models of supernova explosions; believe me, they were very well versed in their field, and they would absolutely kill for a competitive edge over colleagues if they thought for a minute they were missing something obvious. I'm not too familiar with Eta Carinae models, though I have a passing familiarity with the object itself --- not my field. What "stuff" happens? And what does all this have to do with cosmology?
Why do the stars have to be 4 billion years old at the time? Sorry, this isn't at all obvious to me.
That's to your credit. Most astrophysicists would prefer to pretend that, e.g., quantized redshift as referenced to the CMB rest-frame in low-redshift galaxies, or to angularly-nearby low-redshift galaxies in the case of high-redshift galaxies and quasars, don't exist. Most would prefer to pretend that high-redshift quasars (e.g. z=2.11) physically in front of low-redshift opaque galaxies (e.g. NGC 7319, z=0.0225) don't exist.
Well, I know a lot of astrophysicists, and pretending doesn't really have anything to do with it. Your examples are not particularly bothersome because, as is pointed out by another, there are other explanations for these anomalies. Additionally, there is enormous and compelling evidence that our interpretations of redshift and lookback time are robust.
I also never took a "plasma" class, only those standard classes in EM, Thermo, Stat Mech. What is the claim of the engineers? Where are we ignorant?
What? I don't understand your objection. Are you talking about those galaxies that we see as they were 12 billion years ago, or close galaxies 12 billion years old? And what do 4 billion year old stars have to do with it? As an astrophysicist, I'd like to be an apologetic for the standard cosmological model, but I don't understand your problem with it.
We can place an upper limit on the *number* of objects that may compose a massive halo by carefully observing "microlensing" events --- tiny fluctuations in the brightness of distant halo stars due to matter passing in front of them. Many of these events have been observed, but not enough to account for the mass responsible for the so-called anomalous galactic rotation curves. We then think that perhaps there are a lesser number of more massive objects, or something else we haven't thought of yet. In any case, the standard Big Bang model predicts an upper limit on the amount of baryonic matter ("regular" matter, protons/neutrons) in the Universe, so if the massive galactic halos exist, they should still fall under this limit, or there'll be trouble.
I'm not quite sure what you mean by "Dark Matter is far from an accepted Hypothesis". It is certainly not far-fetched to imagine that there is some quantity of matter, perhaps substantial, that does not "glow" like stars do. This is why it is "dark". The original problem was one of galactic rotation curves --- matter in the outskirts of galaxies rotated around the center in a fashion exactly mimicing what it would do if there was a spherical distribution of matter extending beyond the glow of the visible disk. The hypothesis that there was just such a distribution that we cannot see is not so far-fetched. It has been admittedly difficult to identify the "conventional" bodies that could be responsible for the lion's share of such a halo. Upper limits on the numbers of brown dwarfs, Jupiter-sized objects, and small black holes have shown that no one of these are primarily responsible. Still the search continues, as it would in any good scientific theory. Any of these possibilities are seen as a simpler approach than modifying our most basic models of gravitational behavior, especially when there is no similar pattern of deviation from known laws on different scales. And, as shown by the follow-up paper in the archives, there is a real possibility that the authors have made an honest mistake.
But it is not "bunk"; it is reality. I see you have some understanding of relativity, but I'm suggesting that your understanding is incomplete. I'm not picking on you, but there is a subtle issue at stake. When you say "moving apart", you have to be careful in assigning coordinates to those objects. Objects cannot move relative to a set of coordinates faster than the speed of light, but there is no such restriction on how fast the coordinates themselves can expand.
As far as coordinate systems go sure you can set them to change in any way you like, but it is also useless to have them change at a rate greater than c.
No, not useless. In fact it is a prediction of general relativity and most cosmological models, and borne out by simple explanations such as the cosmological redshift, which is not really a Doppler shift at all, but a consequence of the expansion of space-time itself.
Hi,
I don't know if anyone has answered this to your satisfaction yet, but there is a distinction between relative velocities and coordinate velocities. Relative velocities, as described by special relativity, involve measurements of coordinate differences. In general relativity (cosmology, here) there is no restriction upon the rate at which the coordinates themselves (used to describe positions and velocities) can change. As the universe expands, it is the coordinates that change faster than the speed of light, though any local measurements of these coordinates is bound by relativity. It is easiest to think of the galaxies as fairly stationary in space, but carried along by universal expansion. There is no limit to the rate of coordinate expansion.