More (indirect) evidence for Dark Matter

[derekmcd]

<p>Scientist have been on a roll recently concerning dark energy and dark matter.&nbsp; Here's two recent publications concerning dark matter:</p><p>http://www.space.com/scienceastronomy/080827-cosmic-collision.html</p><p>Here's the paper for the above article:</p><p>http://arxiv.org/abs/0806.2320</p><p>&nbsp;</p><p>Not done yet... here's yet more concerning DM.&nbsp;</p><p>http://www.space.com/scienceastronomy/080827-satellite-galaxies.html</p><p>Related paper:</p><p>http://arxiv.org/pdf/0806.4381</p><p>&nbsp;</p><p>Confirmation the Bullet cluster was not a unique phenomena and the "Dwarf Galaxy Problem" concerning dark matter seems to be going away slowly.&nbsp; </p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[michaelmozina]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Scientist have been on a roll recently concerning dark energy and dark matter.&nbsp; Here's two recent publications concerning dark matter:http://www.space.com/scienceastronomy/080827-cosmic-collision.htmlHere's the paper for the above article:http://arxiv.org/abs/0806.2320 </DIV></p><p>IMO, this indormation would suggest that the "missing matter" is found inside the solar systems rather than the the interstellar space around solar system.&nbsp; The distance between solar systems make it unlikely that suns would directly collide, whereas the interstellar plasmas would probably interact.</p> <div class="Discussion_UserSignature"> It seems to be a natural consequence of our points of view to assume that the whole of space is filled with electrons and flying electric ions of all kinds. - Kristian Birkeland </div>

 

[derekmcd]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>IMO, this indormation would suggest that the "missing matter" is found inside the solar systems rather than the the interstellar space around solar system.&nbsp; The distance between solar systems make it unlikely that suns would directly collide, whereas the interstellar plasmas would probably interact. <br /> Posted by michaelmozina</DIV></p><p>I think the dark matter is rather homogenous throughout the galaxy and extending out past the halo.&nbsp; But that is not the issue here concerning clusters.&nbsp; You're correct that stars colliding would be quite rare.&nbsp; Most of the baryonic matter in a cluster is in intergalactic gasses (plasmas if you prefer).&nbsp; It's this gas that collides with the gas from&nbsp; the other cluster. So the gas, which is most of the matter of the two clusters, collide and become displaced as all the galaxies with their dark matter halo pass through each other.</p><p>Essentially, most of the baryonic matter is stripped from each cluster and yet, through lensing measurements, it seems they still retain most of their mass (i.e. dark matter).&nbsp; I can't think of any other explanation other than to say there is some physical matter associated with the clusters that are contributing to their mass that we have yet to be able to physically see/detect.</p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[michaelmozina]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I think the dark matter is rather homogenous throughout the galaxy and extending out past the halo.</DIV></p><p>The evidence would seem to bear that out.&nbsp; IMO the missing mass/dark matter is contained in the physical infrastructure of each and every solar system. </p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>But that is not the issue here concerning clusters.&nbsp; You're correct that stars colliding would be quite rare.&nbsp; Most of the baryonic matter in a cluster is in intergalactic gasses (plasmas if you prefer).</DIV></p><p>I think that's a bad "assumption".&nbsp; The intergalacitic material does seem to "interact" during these collisoins, but the vast majority of mass seems to "pass on through" the collision process.&nbsp; By *assuming* that most baryonic matter is in the plsamas between the stars, you may be setting yourself up here.&nbsp;&nbsp; Some of the matter surely does reside in the interstellar medium, but it's not clear to me that "most" baryonic matter reside in that medium.</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'> It's this gas that collides with the gas from&nbsp; the other cluster. So the gas, which is most of the matter of the two clusters, collide and become displaced as all the galaxies with their dark matter halo pass through each other.Essentially, most of the baryonic matter is stripped from each cluster and yet, through lensing measurements, it seems they still retain most of their mass (i.e. dark matter).&nbsp; I can't think of any other explanation other than to say there is some physical matter associated with the clusters that are contributing to their mass that we have yet to be able to physically see/detect. <br /> Posted by derekmcd</DIV></p><p>IMO you are *assuming* something that doesn't seem to be the case based on the obsservations.&nbsp; You seem to "assume" that the majority of baryonic matter is in the plasma between the stars, whereas these observations would suggest otherwise IMO. &nbsp; Most of the mass seems to "pass on through" these colllision events.&nbsp; That makes sense if "most" of the baryonic matter is contained in the solar system infrastructures of each galaxy. These items would tend to "hold together" and pass on through a collision process, whereas the plasma threads between stars would tend to interact with the plasmas in the other galaxy.&nbsp; If you don't *assume* that most of the baryonic matter resides in the interstellar medium, then it's likely that most of the mass of each galaxy would be relatively uneffected by the collision.</p><p>IMO these studies do suggest that we "missed something", and we underestimate the mass of galaxies.&nbsp; That "something" we missed IMO is the fact that most of the matter in all galaxies resides in the solar system infrastructure, not in the plasmas between the stars.&nbsp; IMO that's the key here to understanding these observations, not the introduction of new forms of non bayonic matter. </p> <div class="Discussion_UserSignature"> It seems to be a natural consequence of our points of view to assume that the whole of space is filled with electrons and flying electric ions of all kinds. - Kristian Birkeland </div>

 

[michaelmozina]

<p>These galaxy collision studies are the "best evidence" of "dark matter" (IMO all in "MACHO" form) over MOND theory.&nbsp; While MOND theory can "explain" rotation rates as well as dark matter theories, it doesn't really explain these sorts of fuzzy interaction pictures between galaxies very well.&nbsp; IMO "dark matter" is therefore a "better" explanation than MOND theory.&nbsp; I'm sure that MOND theory will address these images too, but these sort of "fuzzy" interaction processes we observe in the lensing data suggest to me that dark matter theories are better suited to explain such images.</p><p>I guess as long as you're willing to accept MACHO forms of "dark matter" (which I'm sure you are), I too am actually an advocate of "dark matter". </p><p>&nbsp;</p> <div class="Discussion_UserSignature"> It seems to be a natural consequence of our points of view to assume that the whole of space is filled with electrons and flying electric ions of all kinds. - Kristian Birkeland </div>

 

[UFmbutler]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>These galaxy collision studies are the "best evidence" of "dark matter" (IMO all in "MACHO" form) over MOND theory.&nbsp; While MOND theory can "explain" rotation rates as well as dark matter theories, it doesn't really explain these sorts of fuzzy interaction pictures between galaxies very well.&nbsp; IMO "dark matter" is therefore a "better" explanation than MOND theory.&nbsp; I'm sure that MOND theory will address these images too, but these sort of "fuzzy" interaction processes we observe in the lensing data suggest to me that dark matter theories are better suited to explain such images.I guess as long as you're willing to accept MACHO forms of "dark matter" (which I'm sure you are), I too am actually an advocate of "dark matter". &nbsp; <br /> Posted by michaelmozina</DIV></p><p>I'm surprised there are still even proponents of MOND...&nbsp;</p> <div class="Discussion_UserSignature"> </div>

 

[michaelmozina]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I'm surprised there are still even proponents of MOND...&nbsp; <br /> Posted by UFmbutler</DIV></p><p>Mainstream publications still publish papers that advocate MOND theory.&nbsp; It's not the forbidden topic, and therefore even though it's a minority viewpoint, it still gets published every now and again. </p> <div class="Discussion_UserSignature"> It seems to be a natural consequence of our points of view to assume that the whole of space is filled with electrons and flying electric ions of all kinds. - Kristian Birkeland </div>

 

[UFmbutler]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Mainstream publications still publish papers that advocate MOND theory.&nbsp; It's not the forbidden topic, and therefore even though it's a minority viewpoint, it still gets published every now and again. <br /> Posted by michaelmozina</DIV></p><p>Right, I'm just expressing my annoyance with the idea.&nbsp; The fact that it is published as often as it is only adds confusion to the field.&nbsp; It WAS an interesting idea, but when put to the test(theoretically and observationally) it failed.&nbsp; That is usually when people give up on their alternative theories. &nbsp; </p> <div class="Discussion_UserSignature"> </div>

 

[michaelmozina]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Right, I'm just expressing my annoyance with the idea.</DIV></p><p>&nbsp; Most current cosmology theories annoy me, but for the sake of science, I actually read minority (or opposing) opinions from time to time.&nbsp; I'm glad they still publish minority viewpoints. &nbsp;&nbsp; </p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>The fact that it is published as often as it is only adds confusion to the field.&nbsp; It WAS an interesting idea, but when put to the test(theoretically and observationally) it failed.&nbsp; That is usually when people give up on their alternative theories. &nbsp; <br /> Posted by UFmbutler</DIV></p><p>Keep in mind that the bullet cluster data is "relatively" new, and you can't expect the MOND people to give up until they've had a chance to analyse the images for themselves and see how their ideas might also be used to explain these same phenomenon. &nbsp; For all I know, someone has already published a paper on MOND theory involving the bullet cluster lensing data.&nbsp; If so, I've not read it, but only because I don't have as much interest in that particular theory.&nbsp;&nbsp; </p><p>I would not however get on the mainstream publications for allowing these papers to be published, even if I don't agree with them.&nbsp; I think controversy and alternative ideas are good for science.&nbsp; At some point, some theories should be put aside because the "predictions" dont' match expectations, but that almost never happens in astronomy, regardless of the theory or the data.&nbsp;&nbsp; Even when epicycles were being added to earthcentric ideas, earthcentric ideas were still "popular", regardless of how complex they seemed, and regardless of how wrong they were.&nbsp; Change takes time, particularly in the industry of astronomy. &nbsp; It's not like we can put many of these theories to an emprical test and that what makes it so difficult to "weed out" various ideas, even bad ones. </p> <div class="Discussion_UserSignature"> It seems to be a natural consequence of our points of view to assume that the whole of space is filled with electrons and flying electric ions of all kinds. - Kristian Birkeland </div>

 

[UFmbutler]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp; Most current cosmology theories annoy me, but for the sake of science, I actually read minority (or opposing) opinions from time to time.&nbsp; I'm glad they still publish minority viewpoints. &nbsp;&nbsp; Keep in mind that the bullet cluster data is "relatively" new, and you can't expect the MOND people to give up until they've had a chance to analyse the images for themselves and see how their ideas might also be used to explain these same phenomenon. &nbsp; For all I know, someone has already published a paper on MOND theory involving the bullet cluster lensing data.&nbsp; If so, I've not read it, but only because I don't have as much interest in that particular theory.&nbsp;&nbsp; I would not however get on the mainstream publications for allowing these papers to be published, even if I don't agree with them.&nbsp; I think controversy and alternative ideas are good for science.&nbsp; At some point, some theories should be put aside because the "predictions" dont' match expectations, but that almost never happens in astronomy, regardless of the theory or the data.&nbsp;&nbsp; Even when epicycles were being added to earthcentric ideas, earthcentric ideas were still "popular", regardless of how complex they seemed, and regardless of how wrong they were.&nbsp; Change takes time, particularly in the industry of astronomy. &nbsp; It's not like we can put many of these theories to an emprical test and that what makes it so difficult to "weed out" various ideas, even bad ones. <br /> Posted by michaelmozina</DIV></p><p>I suppose I'm slightly biased because the semester the Bullet cluster discovery was announced, I was in the class of one of the professors who wrote the article(I believe he was third author), and he used it as a way to explain MOND while simultaneously telling us why it was false. &nbsp;</p><p>I always found epicycles interesting...although they were entirely wrong and extremely complicated, they still managed to make fairly accurate predictions.&nbsp; The difference between this kind of science and modern science is they seemed to be only searching for a way to predict, rather than understand.&nbsp; I would imagine they didn't actually believe Mars had something like 50 epicycles in its orbit, but it worked, to some extent.&nbsp; Anyways, thats a little off topic but I just enjoy studying the history of astronomy and how fast it has progressed in the past century or so. </p> <div class="Discussion_UserSignature"> </div>

 

[derekmcd]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>The evidence would seem to bear that out.&nbsp; IMO the missing mass/dark matter is contained in the physical infrastructure of each and every solar system.</DIV></p><p>This statement is not inaccurate.&nbsp; However, it is not entirely complete.&nbsp; These findings are not concerned about scales at the level of stellar systems.&nbsp; They are not even realy concerned with the galactic scale.&nbsp; This is more about the overdense regions referred to as galactic clusters and the intracluster medium and the associated dark matter with these overdense regions.&nbsp;</p><p>Have you actually read the papers, or are you just throwing out your uninformed opinion.&nbsp;</p><p> Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I think that's a bad "assumption".&nbsp; The intergalacitic material does seem to "interact" during these collisoins, but the vast majority of mass seems to "pass on through" the collision process.</DIV></p><p>Exactly!!!&nbsp; How can it be a bad assumption when you just repeated,<strong><em> precisely</em></strong>, what is going on in these collisions?&nbsp;</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>By *assuming* that most baryonic matter is in the plsamas between the stars, you may be setting yourself up here.</DIV></p><p>It's not <em><strong>my</strong></em> assumption.&nbsp; Not to mention that you don't understand what the 'assumption' is.&nbsp; It has little to nothing to do with the interstellar medium. </p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Some of the matter surely does reside in the interstellar medium, but it's not clear to me that "most" baryonic matter reside in that medium.</DIV></p><p>Again, it's not about the interstellar medium.&nbsp; I doubt, during these collisions, that galaxies are even colliding... much less the interstellar medium.&nbsp; This is about the INTRACLUSTER MEDIUM.&nbsp;</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>IMO you are *assuming* something that doesn't seem to be the case based on the obsservations.</DIV></p><p>Educate yourself on what they are actualy observing and get back to me on this statement.&nbsp;</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>You seem to "assume" that the majority of baryonic matter is in the plasma between the stars, whereas these observations would suggest otherwise IMO.</DIV></p><p>Educate yourself on what they are actualy observing and get back to me on this statement. </p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Most of the mass seems to "pass on through" these colllision events.</DIV></p><p>Agreed.&nbsp;</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>That makes sense if "most" of the baryonic matter is contained in the solar system infrastructures of each galaxy.</DIV></p><p>I understand what you are alluding to.&nbsp; However, this has nothing to do with what they are observing.&nbsp; Familiarize yourself with it an you might understand.&nbsp; First, it is highly unlikely that the galaxies within the cluster are actually colliding.&nbsp; Again, this is about the intracluster medium.&nbsp; What they are observing is a large portion of the visible matter is being left behind as these clusters pass throug each other.&nbsp; Through lensing data, they measure that these two cluster have retained their mass despite leaving behind most of their visible matter.&nbsp; In other words, the visible matter of each cluster is really insignificant when measuring their overall mass.&nbsp;</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>These items would tend to "hold together" and pass on through a collision process, whereas the plasma threads between stars would tend to interact with the plasmas in the other galaxy.</DIV></p><p>Nothing to do with what is going on between stars.&nbsp;</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>If you don't *assume* that most of the baryonic matter resides in the interstellar medium, then it's likely that most of the mass of each galaxy would be relatively uneffected by the collision.</DIV></p><p>Nothing to do with what is going on between starts.&nbsp;</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>IMO these studies do suggest that we "missed something", and we underestimate the mass of galaxies.</DIV></p><p>This has nothing to do with individual galaxies, so you should say "IM uniformed O".&nbsp;</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>That "something" we missed IMO is the fact that most of the matter in all galaxies resides in the solar system infrastructure, not in the plasmas between the stars.</DIV></p><p>Another uninformed opinion.&nbsp;</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>IMO that's the key here to understanding these observations, not the introduction of new forms of non bayonic matter. <br /> Posted by michaelmozina</DIV></p><p>Folks have tried.&nbsp; MOND and TeVeS have put forth a yeoman-like effort to explain this.&nbsp; However, they have come up short.&nbsp; They still have their foot in the door and may still have something to contribute, but it's not looking good.&nbsp; The difference between the MOND folks and you is that the MOND folks actually understand what it is they are trying compete with.</p><p>Nothing wrong with thinking outside the box.&nbsp; However, it is highly recommended to understand what is going on *inside* first. </p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[derekmcd]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>These galaxy collision studies are the "best evidence" of "dark matter" (IMO all in "MACHO" form) over MOND theory.&nbsp; While MOND theory can "explain" rotation rates as well as dark matter theories, it doesn't really explain these sorts of fuzzy interaction pictures between galaxies very well.&nbsp; IMO "dark matter" is therefore a "better" explanation than MOND theory.&nbsp; I'm sure that MOND theory will address these images too, but these sort of "fuzzy" interaction processes we observe in the lensing data suggest to me that dark matter theories are better suited to explain such images.I guess as long as you're willing to accept MACHO forms of "dark matter" (which I'm sure you are), I too am actually an advocate of "dark matter". &nbsp; <br /> Posted by michaelmozina</DIV></p><p>I'm actually impressed with this statement.&nbsp; I'm not your father, but I welcome you to the "Dark Side".&nbsp; MACHOs haven't been entirely ruled out.&nbsp; However, it's rather unlikely they can account for the observations. </p><p>&nbsp;</p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[michaelmozina]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I'm actually impressed with this statement.&nbsp; I'm not your father, but I welcome you to the "Dark Side".&nbsp; MACHOs haven't been entirely ruled out.&nbsp; However, it's rather unlikely they can account for the observations. &nbsp; <br /> Posted by derekmcd</DIV></p><p>Cute,&nbsp; &nbsp; FYI, I was introduced to MACHO variations of "dark matter" a very long time ago, and I have never had any philosphical problem with that idea. &nbsp; I have always thought that MACHO variations of dark matter were preferable over MOND type theories and the galaxy collision studies do tend to favor "dark matter" IMO.&nbsp; It's primarily the SUSY brand of DM I have emprical philosophical problems with. &nbsp; </p> <div class="Discussion_UserSignature"> It seems to be a natural consequence of our points of view to assume that the whole of space is filled with electrons and flying electric ions of all kinds. - Kristian Birkeland </div>

 

[michaelmozina]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>This statement is not inaccurate.&nbsp; However, it is not entirely complete.&nbsp; These findings are not concerned about scales at the level of stellar systems.&nbsp; They are not even realy concerned with the galactic scale.&nbsp; This is more about the overdense regions referred to as galactic clusters and the intracluster medium and the associated dark matter with these overdense regions.&nbsp;Have you actually read the papers, or are you just throwing out your uninformed opinion.&nbsp; </DIV></p><p>I've read the bullet cluster paper a number of time, but not the latest study (I just looked at the pretty picture of that study). &nbsp; I have actually been focused on the Scchindler, Hesse ad Birn paper as of late.</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Exactly!!!&nbsp; How can it be a bad assumption when you just repeated, precisely, what is going on in these collisions?&nbsp;It's not my assumption.&nbsp; Not to mention that you don't understand what the 'assumption' is.&nbsp; It has little to nothing to do with the interstellar medium. Again, it's not about the interstellar medium.&nbsp; I doubt, during these collisions, that galaxies are even colliding... much less the interstellar medium.&nbsp; This is about the INTRACLUSTER MEDIUM.&nbsp;Educate yourself on what they are actualy observing and get back to me on this statement.</DIV></p><p>Um, call it what you like Derek, and explain it as you like.&nbsp; However you choose to look at it, a large part of the mass of each galaxy passes right through the other, and seems unaffected by any sort of "collision" according to these studies.&nbsp;&nbsp; This can be explained by the fact that direct "hits" between the solar systems are highly unlikely, whereas the the plasma that conducts current between stars does seem to interact with plasma from the other galaxy.&nbsp; IMO this is likely due to the fact that the physical "arms" of solar systems in each galaxy rarely if ever collide, whereas some amount of the plasma between the stars in each galaxy interacts with the plasma from the other galaxy.&nbsp; The "intercluster medium" is composed of what used to be "interstellar medium" from each of the two galaxies.</p><p>FYI, I accept that each galaxy probably also contains a heavy central object (like a black holes but without infinite density) which is highly unlikely to collide with the heavy central object in the other galaxy.&nbsp; These would likely "pass through" the collision process unless they are moving very slowly in relationship to one another. &nbsp;</p><p>Again, like all uncontrolled observations, these observations are open to subjective interpretation. &nbsp; What is clear however is that much of the mass of each galaxy simply passes right through the "collision'&nbsp; process. </p> <div class="Discussion_UserSignature"> It seems to be a natural consequence of our points of view to assume that the whole of space is filled with electrons and flying electric ions of all kinds. - Kristian Birkeland </div>

 

[derekmcd]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I've read the bullet cluster paper a number of time, but not the latest study (I just looked at the pretty picture of that study). &nbsp; I have actually been focused on the Scchindler, Hesse ad Birn paper as of late.</DIV></p><p>That's ok.&nbsp; There's nothing groundbreakingly new in this paper.&nbsp; It's really just a reaffirmation that the Bullet cluster observations are not unique.&nbsp;</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Um, call it what you like Derek, and explain it as you like.&nbsp; However you choose to look at it, a large part of the mass of each galaxy passes right through the other, and seems unaffected by any sort of "collision" according to these studies.&nbsp; This can be explained by the fact that direct "hits" between the solar systems are highly unlikely, whereas the the plasma that conducts current between stars does seem to interact with plasma from the other galaxy.&nbsp; IMO this is likely due to the fact that the physical "arms" of solar systems in each galaxy rarely if ever collide, whereas some amount of the plasma between the stars in each galaxy interacts with the plasma from the other galaxy.&nbsp; The "intercluster medium" is composed of what used to be "interstellar medium" from each of the two galaxies.FYI, I accept that each galaxy probably also contains a heavy central object (like a black holes but without infinite density) which is highly unlikely to collide with the heavy central object in the other galaxy.&nbsp; These would likely "pass through" the collision process unless they are moving very slowly in relationship to one another. &nbsp;Again, like all uncontrolled observations, these observations are open to subjective interpretation. &nbsp; What is clear however is that much of the mass of each galaxy simply passes right through the "collision'&nbsp; process. <br /> Posted by michaelmozina</DIV></p><p>I understand you are tied up with the other thread, but this conversation can't continue unless you 'refresh' yourself with what these papers are actually saying.&nbsp; This has nothing to do with inidividual galaxies colliding so your argument makes no sense.</p><p>&nbsp;</p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[michaelmozina]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>That's ok.&nbsp; There's nothing groundbreakingly new in this paper.&nbsp; It's really just a reaffirmation that the Bullet cluster observations are not unique.&nbsp;I understand you are tied up with the other thread, but this conversation can't continue unless you 'refresh' yourself with what these papers are actually saying.&nbsp; This has nothing to do with inidividual galaxies colliding so your argument makes no sense.&nbsp; <br /> Posted by derekmcd</DIV></p><p>In an effort to save us both some time here, how about you explain these basic results in your own words, and I'll comment where I have any type of disagreement, or I have anything to add.&nbsp; There is no point in talking past one another here since we both seem to agree that there is evidence here of "dark matter" (IMO MAHCO), and there must be a way to simplify this discussion. </p> <div class="Discussion_UserSignature"> It seems to be a natural consequence of our points of view to assume that the whole of space is filled with electrons and flying electric ions of all kinds. - Kristian Birkeland </div>

 

[derekmcd]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>In an effort to save us both some time here, how about you explain these basic results in your own words, and I'll comment where I have any type of disagreement, or I have anything to add.&nbsp; There is no point in talking past one another here since we both seem to agree that there is evidence here of "dark matter" (IMO MAHCO), and there must be a way to simplify this discussion. <br /> Posted by michaelmozina</DIV></p><p>I already did... twice.&nbsp;</p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[Univrslneed27]

<p>By all means, simplify this dark matter a little more. </p> <div class="Discussion_UserSignature"> </div>

 

[MeteorWayne]

<p>&nbsp;Full Story Here</p><p>http://www.space.com/scienceastronomy/080918-dark-matter.html</p><p>&nbsp;</p><table border="0"><tbody><tr><td width="355" align="left" valign="top"><font face="Verdana, Helvetica, sans-serif" size="3" color="#1b4872"><strong>Nearby Galaxy Nearly Invisible </strong><br /><font face="Verdana, Helvetica, sans-serif" size="1" color="#333333"><strong>By SPACE.com Staff</strong><br /><br /></font></font><font face="arial,helvetica" size="1" color="#330066">posted: 18 September 2008<br />12:08 pm ET</font><br />

 

[derekmcd]

<p>Here's the associated pre-print: (have yet to see where/when it is going to be published)</p><p>http://arxiv.org/abs/0809.2781</p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[MeteorWayne]

Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Here's the associated pre-print: (have yet to see where/when it is going to be published)http://arxiv.org/abs/0809.2781 <br />Posted by derekmcd</DIV><br /><br />Thanx! <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>