Does dark matter come in two types?
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From: Yousuf Khan on 12 Jun 2010 00:06 On 6/10/2010 1:41 AM, BURT wrote: > If dark matter had a common origin with normal matter at the Big Bang > they must always be found together but they are not. There should be > an even mix and there is not and there nothing to seperate them. I > challenge anyone. > > Mitch Raemsch You said something smart, finally. Yousuf Khan
From: BURT on 12 Jun 2010 19:09 On Jun 11, 9:06 pm, Yousuf Khan <bbb...(a)spammenot.yahoo.com> wrote: > On 6/10/2010 1:41 AM, BURT wrote: > > > If dark matter had a common origin with normal matter at the Big Bang > > they must always be found together but they are not. There should be > > an even mix and there is not and there nothing to seperate them. I > > challenge anyone. > > > Mitch Raemsch > > You said something smart, finally. > > Yousuf Khan All the things you don't think are smart are facts. These are the facts of the future and I can wait. Mitch Raemsch
From: Yousuf Khan on 13 Jun 2010 01:10 On 6/10/2010 7:11 AM, eric gisse wrote: > Yousuf Khan wrote: > >> Or how about the most obvious answer? Dark Matter comes in no types, it >> doesn't exist. These two scientists are just trying to find new ways to >> justify a failed theory. > > Bullet cluster. Hardly conclusive of anything, lots of alternative explanations than Dark Matter. We've had this conversation before, many many times in the past. You usually say "Bullet Cluster", and then I usually say "Abell 520". This conversation repeats itself every few months, and nothing gets settled. > Pick your new physics - either gravitation or particle physics, either way a > field gets rewritten. Okay then I pick gravitation, that's the one due for a rewrite. >> There is already quite convincing alternative explanations for the >> PAMELA positron detections, namely that it's produced by supernovas. Not >> just any supernovas, but a very specific type of supernova recently >> discovered, one that produces Calcium and Titanium. > > One can't help but wonder how exceedingly rare supernovae can generate a > consistent background of signal. Because it's not the supernova itself producing it directly, it's its leftover product, Titanium-44, which is radioactive and decays slowly over time. Titanium-44 produces positrons in its decay. Yousuf Khan
From: eric gisse on 13 Jun 2010 03:13 Yousuf Khan wrote: > On 6/10/2010 7:11 AM, eric gisse wrote: >> Yousuf Khan wrote: >> >>> Or how about the most obvious answer? Dark Matter comes in no types, it >>> doesn't exist. These two scientists are just trying to find new ways to >>> justify a failed theory. >> >> Bullet cluster. > > Hardly conclusive of anything, lots of alternative explanations than > Dark Matter. Precious few. MOND? laff TeVeS? Shifts the problem back exactly 1 step via insertion of almost completely arbitrary vector & scalar fields. How many dark matter alternatives survive scrutiny of the bullet cluster in isolation? > > We've had this conversation before, many many times in the past. You > usually say "Bullet Cluster", and then I usually say "Abell 520". Then I roll my eyes and point out that Abell is a bit of a mess, and then I point out a handful more examples that involve clean collisions... Abell 520 is not the ideal test area for anything except the abilities of numerical physicists. > This > conversation repeats itself every few months, and nothing gets settled. > >> Pick your new physics - either gravitation or particle physics, either >> way a field gets rewritten. > > Okay then I pick gravitation, that's the one due for a rewrite. Why? The standard model is only good to a cutoff of about a TeV. Quantum field theory gets the cosmological constant (nee vacuum energy) wrong by about 100 orders of magnitude. I, personally, don't find it that hard to believe that quantum theory is the one with the problem. > >>> There is already quite convincing alternative explanations for the >>> PAMELA positron detections, namely that it's produced by supernovas. Not >>> just any supernovas, but a very specific type of supernova recently >>> discovered, one that produces Calcium and Titanium. >> >> One can't help but wonder how exceedingly rare supernovae can generate a >> consistent background of signal. > > > Because it's not the supernova itself producing it directly, it's its > leftover product, Titanium-44, which is radioactive and decays slowly > over time. Titanium-44 produces positrons in its decay. Doesn't sit quite right with me, but that's just a lack of information more than anything else. > > Yousuf Khan
From: Yousuf Khan on 13 Jun 2010 14:27
On 6/13/2010 1:13 PM, eric gisse wrote: > Yousuf Khan wrote: >> On 6/10/2010 7:11 AM, eric gisse wrote: >>> Bullet cluster. >> >> Hardly conclusive of anything, lots of alternative explanations than >> Dark Matter. > > Precious few. > > MOND? laff > TeVeS? Shifts the problem back exactly 1 step via insertion of almost > completely arbitrary vector& scalar fields. > > How many dark matter alternatives survive scrutiny of the bullet cluster in > isolation? A: Dark Fluid. Dark Fluid not only explains the Bullet Cluster, it also explains the Train Wreck Cluster (Abell 520). Dark Fluid also avoids the "Black Hole trap" that affected TeVeS, because there is a built-in repulsive force element, otherwise known as Dark Energy. *** Has 'dark fluid' saved Earth from oblivion? "The dark fluid can also reconcile the observations of what happened in the Bullet and train-wreck clusters. Whereas previous modified gravity theories cannot explain why the two collisions ended up differently, this is not a problem with Zhao's theory because the distribution of the dark fluid - and therefore of the enhanced gravity effect - can vary. Zhao likens the interaction between visible matter and the dark fluid to the interplay between wind and the surface of an ocean. Disturbances in one will affect the other, but depending on how the disturbances were created and the surrounding conditions, ocean turbulence can overshoot wind turbulence or lag behind it. In the case of the Bullet cluster, the dark fluid may have sloshed forward, piling up beyond the visible matter. In the train wreck, the fluid may have lagged behind visible matter. " http://www.philosophychatforum.com/viewtopic.php?f=2&t=8478 >> We've had this conversation before, many many times in the past. You >> usually say "Bullet Cluster", and then I usually say "Abell 520". > > Then I roll my eyes and point out that Abell is a bit of a mess, and then I > point out a handful more examples that involve clean collisions... > > Abell 520 is not the ideal test area for anything except the abilities of > numerical physicists. You can't have it both ways; you can't accept one cluster because it agrees with your expectations, but ignore the ones that don't. You can't even exclude the Train Wreck as a statistical outlier because there aren't that many other examples similar to Bullet either. It's basically a tale of two clusters, right now. >>> Pick your new physics - either gravitation or particle physics, either >>> way a field gets rewritten. >> >> Okay then I pick gravitation, that's the one due for a rewrite. > > Why? > > The standard model is only good to a cutoff of about a TeV. Quantum field > theory gets the cosmological constant (nee vacuum energy) wrong by about 100 > orders of magnitude. > > I, personally, don't find it that hard to believe that quantum theory is the > one with the problem. Oh, quantum mechanics needs a rewrite too, no doubt about that. However, it's not even really relevant to this discussion yet. We're still only talking about scales far beyond quantum scale. Before we even get a good working theory of Quantum Gravity down, we should get a good working theory of just regular old Gravity down. Just like all of the contradictory observations (like the orbit of Mercury around the Sun) signaled a problem with Newtonian Gravity, that signaled the end of its era, eventually leading to the Einstein's GR era. All of these contradictory readings (galaxy rotation, cosmic expansions, etc.) we're seeing all over the place means the end of the GR era is coming too. There's even more contradictory observations here than that which led to the end of Newtonian Gravity. However, we're fighting even harder to preserve the current GR paradigm than it ever took to overthrow Newton's paradigm. We're fighting to preserve GR by making ourselves believe in all kinds of invisible magical mystery substances, with little more faith than that needed to believe in all of the magic in a Harry Potter movie. >>>> There is already quite convincing alternative explanations for the >>>> PAMELA positron detections, namely that it's produced by supernovas. Not >>>> just any supernovas, but a very specific type of supernova recently >>>> discovered, one that produces Calcium and Titanium. >>> >>> One can't help but wonder how exceedingly rare supernovae can generate a >>> consistent background of signal. >> >> >> Because it's not the supernova itself producing it directly, it's its >> leftover product, Titanium-44, which is radioactive and decays slowly >> over time. Titanium-44 produces positrons in its decay. > > Doesn't sit quite right with me, but that's just a lack of information more > than anything else. Short Sharp Science: New supernova class may undermine dark matter search "The titanium is radioactive and emits positrons as it decays. Over the past couple of years, there have been reports from experiments such as ATIC and PAMELA of an excess of positrons coming from deep space. This excess, it has been argued, is a signature of dark matter particles colliding. But if the new supernova finding is anything to go by, these explosions could be quite commonplace and they could be the source of the excess positrons." http://www.newscientist.com/blogs/shortsharpscience/2010/05/new-supernova-class-may-underm.html Yousuf Khan |