Re: doesn't dark matter falsify general relativity?
I think I'll call it Relativi-stuck cosmology. On 9 December 2013 13:22, LizR lizj...@gmail.com wrote: I'm working on a theory that galaxies are held together by duct tape and superglue. It's proving a little tricky. Obviously the tape has to be arranged so the dark side is facing towards us... -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
On 07 Dec 2013, at 23:58, John Mikes wrote: Telmo asked: Honest question: isn't dark matter a fancy name for failed predictions? I would not be so rude - just call it an ingenious way to save our scientific face in so far developed conventional science. Then it required 'dark energy' in the dark minds.And ALL had been justified by the theories to be justified. I don't think we can, justify our theories. We can feel happy to get them, happy to see them working for a while, and we can be doubly happy when they are shown wrong, as this means that we will learn something. Dark matter is rather sadly amazing in that respect. God: - what are the news? God's engineer: - I am afraid humans have found that galaxies structures is inconsistent with the matter they can see! God:- Gosh! What can we do? God's engineer:- we can add invisible matter, perhaps. God:- do that! excellent idea, they will see nothing God's engineer:- Hmm, they will see it indirectly, through lenticular structure, and galaxies nice behaviors, God:- do we need a lot of them? God's engineer:- well, 90% of matter needs to be made of that invisible stuff ... God:- damned!shhh . (depression). ;) Bruno John M On Fri, Nov 29, 2013 at 6:05 AM, Telmo Menezes te...@telmomenezes.com wrote: On Wed, Nov 27, 2013 at 5:03 PM, Jesse Mazer laserma...@gmail.com wrote: Dark matter behaves pretty convincingly like large clumps of matter that, aside from not interacting with normal matter via non- gravitational forces, obeys the same sort of dynamical laws as any other form of matter, see the following for a good quick summary (note particularly the stuff about the colliding galaxy clusters whose dark matter halos seemed to outshoot the position of the visible clusters themselves, since the visible matter like stars is slowed down via friction with gas and dust during the collision, but friction is an electromagnetic interaction so dark matter should be impervious to it): http://scienceblogs.com/startswithabang/2010/06/24/convincing-a-young-scientist-t/ Thanks Jesse, very nice article. On Wed, Nov 27, 2013 at 7:40 AM, Telmo Menezes te...@telmomenezes.com wrote: Hi all, Honest question: isn't dark matter a fancy name for failed predictions? Cheers, Telmo. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com . Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com . Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out. http://iridia.ulb.ac.be/~marchal/ -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
I'm working on a theory that galaxies are held together by duct tape and superglue. It's proving a little tricky. Obviously the tape has to be arranged so the dark side is facing towards us... -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
On Fri, Dec 6, 2013 at 5:28 PM, LizR lizj...@gmail.com wrote: If you were falling back first into a Black Hole things that were behind you would start to look as if they were ahead of you, and as you got very close to the event horizon all the light from the entire external universe would be coming to you from a small disk directly in front of you. When you actually crossed the event horizon (the point of no return) the diameter of that disk would shrink to zero and you'd be forever cutoff from the universe you knew. If the Black Hole were large enough you could still be alive when you crossed the event horizon, although a few seconds later tidal forces would rip you apart through spaghettification[...] at the event horizon of one of Einstein's Black Holes, even if the gravity was only 1g, you could never escape the Black Hole and return to Earth no matter how powerful your rocket is; on the surface of Michell's dark star even if it was a billion g you could escape if your rocket was powerful enough (assuming a billion g didn't prove harmful to your health). it's a fascinating concept. Yes. What a shame it can't happen in the real world. How do you figure that? John K Clark -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
Telmo asked: *Honest question: isn't dark matter a fancy name for failed predictions?* *I would not be so rude * - just call it an ingenious way to save our scientific face in so far developed conventional science. Then it required 'dark energy' in the dark minds.And ALL had been justified by the theories to be justified. John M On Fri, Nov 29, 2013 at 6:05 AM, Telmo Menezes te...@telmomenezes.comwrote: On Wed, Nov 27, 2013 at 5:03 PM, Jesse Mazer laserma...@gmail.com wrote: Dark matter behaves pretty convincingly like large clumps of matter that, aside from not interacting with normal matter via non-gravitational forces, obeys the same sort of dynamical laws as any other form of matter, see the following for a good quick summary (note particularly the stuff about the colliding galaxy clusters whose dark matter halos seemed to outshoot the position of the visible clusters themselves, since the visible matter like stars is slowed down via friction with gas and dust during the collision, but friction is an electromagnetic interaction so dark matter should be impervious to it): http://scienceblogs.com/startswithabang/2010/06/24/convincing-a-young-scientist-t/ Thanks Jesse, very nice article. On Wed, Nov 27, 2013 at 7:40 AM, Telmo Menezes te...@telmomenezes.com wrote: Hi all, Honest question: isn't dark matter a fancy name for failed predictions? Cheers, Telmo. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
On 8 December 2013 11:58, John Mikes jami...@gmail.com wrote: Telmo asked: *Honest question: isn't dark matter a fancy name for failed predictions?* *I would not be so rude * - just call it an ingenious way to save our scientific face in so far developed conventional science. Then it required 'dark energy' in the dark minds.And ALL had been justified by the theories to be justified. John M We shouldn't be surprised there is stuff out there we can't see. Observation has already revealed a whole bunch of stuff we couldn't detect as little as a century ago, what are the chances we can see the whole Hubble Schmeer yet? -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
On Thu, Dec 5, 2013 at 8:11 PM, LizR lizj...@gmail.com wrote: Ah yes I've heard that the gravity at the event horizon can be as weak as you like with a suitably large hole - that you might not even realise you'd crossed it Yes. though surely you'd get some optical effects? If you were falling back first into a Black Hole things that were behind you would start to look as if they were ahead of you, and as you got very close to the event horizon all the light from the entire external universe would be coming to you from a small disk directly in front of you. When you actually crossed the event horizon (the point of no return) the diameter of that disk would shrink to zero and you'd be forever cutoff from the universe you knew. If the Black Hole were large enough you could still be alive when you crossed the event horizon, although a few seconds later tidal forces would rip you apart through spaghettification So the Michell star is effectively like a solid version of a black hole's event horizon. It's more than that, at the event horizon of one of Einstein's Black Holes, even if the gravity was only 1g, you could never escape the Black Hole and return to Earth no matter how powerful your rocket is; on the surface of Michell's dark star even if it was a billion g you could escape if your rocket was powerful enough (assuming a billion g didn't prove harmful to your health). John K Clark -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
It's a fascinating concept. What a shame it can't happen in the real world. On 7 December 2013 07:42, John Clark johnkcl...@gmail.com wrote: On Thu, Dec 5, 2013 at 8:11 PM, LizR lizj...@gmail.com wrote: Ah yes I've heard that the gravity at the event horizon can be as weak as you like with a suitably large hole - that you might not even realise you'd crossed it Yes. though surely you'd get some optical effects? If you were falling back first into a Black Hole things that were behind you would start to look as if they were ahead of you, and as you got very close to the event horizon all the light from the entire external universe would be coming to you from a small disk directly in front of you. When you actually crossed the event horizon (the point of no return) the diameter of that disk would shrink to zero and you'd be forever cutoff from the universe you knew. If the Black Hole were large enough you could still be alive when you crossed the event horizon, although a few seconds later tidal forces would rip you apart through spaghettification So the Michell star is effectively like a solid version of a black hole's event horizon. It's more than that, at the event horizon of one of Einstein's Black Holes, even if the gravity was only 1g, you could never escape the Black Hole and return to Earth no matter how powerful your rocket is; on the surface of Michell's dark star even if it was a billion g you could escape if your rocket was powerful enough (assuming a billion g didn't prove harmful to your health). John K Clark -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
On Wed, Dec 4, 2013 at 8:12 PM, LizR lizj...@gmail.com wrote: The earliest reference I can find is 1783 by John Michell, he called them dark stars, however it had very different properties from a modern Black Hole. If I was far from one of Michell's Newtonian dark stars I could not see it, but unlike a real Black Hole, I could obtain a picture of it and print it in the newspaper, I'd just have to get closer in a powerful spaceship. I could even land on the classical dark star, get a sample of it and then return it to Earth, that sort of thing would be impossible with a real Einsteinian Black Hole. That's the one. It was used in a story by Brian Aldiss, I guess before black holes became widely known about in SF circles (which was probably thanks to Larry Niven). Of course one could only land on it if one could withstand the gravity, If it was large enough the surface gravity on one of Michell's dark stars could be a earth like 1g or even less. The escape velocity from the surface of a object depends on BOTH its surface gravity and how big the object is because that determines how fast the gravity weakens with distance from the surface, with big objects even a long way away the gravity is almost as strong as it is on the surface. Actually if it were big enough even with Einstein's Black Hole the gravity at the event horizon could be 1g, although after passing that point of no return you would find the gravity increasing continually until it reached infinity at the singularity at the center of the hole. and only take off if one could travel faster than light No, a continuously thrusting rocket could escape from one of Michell's dark stars as slowly as you'd like just like you can from the Earth, but not so with Einstein's Black Hole, from that there is no way out. John K Clark -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
On 6 December 2013 03:00, John Clark johnkcl...@gmail.com wrote: On Wed, Dec 4, 2013 at 8:12 PM, LizR lizj...@gmail.com wrote: The earliest reference I can find is 1783 by John Michell, he called them dark stars, however it had very different properties from a modern Black Hole. If I was far from one of Michell's Newtonian dark stars I could not see it, but unlike a real Black Hole, I could obtain a picture of it and print it in the newspaper, I'd just have to get closer in a powerful spaceship. I could even land on the classical dark star, get a sample of it and then return it to Earth, that sort of thing would be impossible with a real Einsteinian Black Hole. That's the one. It was used in a story by Brian Aldiss, I guess before black holes became widely known about in SF circles (which was probably thanks to Larry Niven). Of course one could only land on it if one could withstand the gravity, If it was large enough the surface gravity on one of Michell's dark stars could be a earth like 1g or even less. The escape velocity from the surface of a object depends on BOTH its surface gravity and how big the object is because that determines how fast the gravity weakens with distance from the surface, with big objects even a long way away the gravity is almost as strong as it is on the surface. Actually if it were big enough even with Einstein's Black Hole the gravity at the event horizon could be 1g, although after passing that point of no return you would find the gravity increasing continually until it reached infinity at the singularity at the center of the hole. Ah yes I've heard that the gravity at the event horizon can be as weak as you like with a suitably large hole - that you might not even realise you'd crossed it (though surely you'd get some optical effects?) So the Michell star is effectively like a solid version of a black hole's event horizon. If that makes sense. and only take off if one could travel faster than light No, a continuously thrusting rocket could escape from one of Michell's dark stars as slowly as you'd like just like you can from the Earth, but not so with Einstein's Black Hole, from that there is no way out. I suppose one could have a space elevator or whatever and just climb gently out of the gravity well.That's very interesting. It makes me rather sad that such objects can't exist, because they'd make for some interesting fiction, and maybe fact. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
On Mon, Dec 2, 2013 at 4:14 PM, LizR lizj...@gmail.com wrote: the 1919 eclipse data is actually somewhat equivocal, despite catapulting Einstein to fame. Back then the measurement was made right at the limit of what was possible with 1919 technology, since then it has been repeated many times with vastly greater precision and Einstein has always passed the test with flying colors. someone predicted black holes way before Einstein, too, on the basis of Newtonian gravity and the measurement of c - although without realising the full implications ... Mitchell???). The earliest reference I can find is 1783 by John Michell, he called them dark stars, however it had very different properties from a modern Black Hole. If I was far from one of Michell's Newtonian dark stars I could not see it, but unlike a real Black Hole, I could obtain a picture of it and print it in the newspaper, I'd just have to get closer in a powerful spaceship. I could even land on the classical dark star, get a sample of it and then return it to Earth, that sort of thing would be impossible with a real Einsteinian Black Hole. John K Clark -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
On 5 December 2013 06:58, John Clark johnkcl...@gmail.com wrote: On Mon, Dec 2, 2013 at 4:14 PM, LizR lizj...@gmail.com wrote: the 1919 eclipse data is actually somewhat equivocal, despite catapulting Einstein to fame. Back then the measurement was made right at the limit of what was possible with 1919 technology, since then it has been repeated many times with vastly greater precision and Einstein has always passed the test with flying colors. That's right, yes. Indeed the most accurate measurement ever made is, I believe, a test of GR involving gravity waves from a binary neutron star. My point was that the eclipse result wasn't - apparently - quite as cut and dried as it was presented, but the person who made it (was that Eddington?) was keen to show Einstein correct. someone predicted black holes way before Einstein, too, on the basis of Newtonian gravity and the measurement of c - although without realising the full implications ... Mitchell???). The earliest reference I can find is 1783 by John Michell, he called them dark stars, however it had very different properties from a modern Black Hole. If I was far from one of Michell's Newtonian dark stars I could not see it, but unlike a real Black Hole, I could obtain a picture of it and print it in the newspaper, I'd just have to get closer in a powerful spaceship. I could even land on the classical dark star, get a sample of it and then return it to Earth, that sort of thing would be impossible with a real Einsteinian Black Hole. That's the one. It was used in a story by Brian Aldiss, I guess before black holes became widely known about in SF circles (which was probably thanks to Larry Niven). Of course one could only land on it if one could withstand the gravity, and only take off if one could travel faster than light - but although those would have been ridiculous goals in Newtonian theory, they weren't considered physically impossible. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
On 3 December 2013 19:46, meekerdb meeke...@verizon.net wrote: We were both a little drunk, but he was serious. I asked if the blob of metal had been tracked in orbit? Zwicky said it was too small to track by radar. So then I asked how they knew it entered orbit. He said they knew because telemetry from the second stage rocket showed that it had fired the shaped charge at the right altitude and right direction. I had not recalled this for many years; the party was in 1963. Consulting the internet (which remembers everything, many of which actually happened) I find that Zwicky wrote a paper about these experiments which differs somewhat from my recollection. http://calteches.library.caltech.edu/1801/1/zwicky.pdf That is seriously impressive, even if it was slightly after Sputnik as it turns out, he was still first to launch something at above escape velocity, so those pellets are presumably still orbiting the Sun. PS Another 50th anniversary (of your party). They are coming thick and fast at the moment, 1963 was a rather momentous year it seems. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
On 2 December 2013 20:14, meekerdb meeke...@verizon.net wrote: On 12/1/2013 7:35 PM, LizR wrote: On 2 December 2013 16:16, Richard Ruquist yann...@gmail.com wrote: MOND is an alternative explanation that replaces Dark Matter by modifying gravity. Yes (hence the flippant remark about bolt on extras) Dark Matter results when gravity is not modified. (pure Newtonian) Or rather Einsteinian, I don't think Newtonian gravity predicts gravitational lensing? Sure it does, but only half as strong as GR. Ah yes, that's right. I believe that's why the 1919 eclipse data is actually somewhat equivocal, despite catapulting Einstein to fame. (And someone predicted black holes way before Einstein, too, on the basis of Newtonian gravity and the measurement of c - although without realising the full implications ... Mitchell???). Mind you, I think my correction above is still pertinent - that is, it's still truer to say that dark matter is what results when gravity is not modified (pure *Einsteinian*). -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
On 12/2/2013 1:14 PM, LizR wrote: On 2 December 2013 20:14, meekerdb meeke...@verizon.net mailto:meeke...@verizon.net wrote: On 12/1/2013 7:35 PM, LizR wrote: On 2 December 2013 16:16, Richard Ruquist yann...@gmail.com mailto:yann...@gmail.com wrote: MOND is an alternative explanation that replaces Dark Matter by modifying gravity. Yes (hence the flippant remark about bolt on extras) Dark Matter results when gravity is not modified. (pure Newtonian) Or rather Einsteinian, I don't think Newtonian gravity predicts gravitational lensing? Sure it does, but only half as strong as GR. Ah yes, that's right. I believe that's why the 1919 eclipse data is actually somewhat equivocal, despite catapulting Einstein to fame. (And someone predicted black holes way before Einstein, too, on the basis of Newtonian gravity and the measurement of c - although without realising the full implications ... Mitchell???). Mind you, I think my correction above is still pertinent - that is, it's still truer to say that dark matter is what results when gravity is not modified (pure /Einsteinian/). Dark matter would be implied by the same observations even assuming Newtonian gravity. Just the amount would be different. I don't know if Fritz Zwicky even used relativistic calculations of rotation curves of galaxies to infer dark matter - it wouldn't have been necessary since the motions are not that fast. Incidentally I met Zwicky at a party once and he regalled me with the story of how he and a NACA team had actually beaten the Russians into space by launching an artificial satellite *before* Sputnik. When I expressed surprise that I had never heard of this satellite, he explained that it was launched from a B-50 flying at 50kft over the equator using a two stage rocket. When the second stage reached it's apogee, it fired a shaped charge which sent a molten mass of metal into orbit around the Earth. Brent -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
On 3 December 2013 11:55, meekerdb meeke...@verizon.net wrote: On 12/2/2013 1:14 PM, LizR wrote: On 2 December 2013 20:14, meekerdb meeke...@verizon.net wrote: On 12/1/2013 7:35 PM, LizR wrote: On 2 December 2013 16:16, Richard Ruquist yann...@gmail.com wrote: MOND is an alternative explanation that replaces Dark Matter by modifying gravity. Yes (hence the flippant remark about bolt on extras) Dark Matter results when gravity is not modified. (pure Newtonian) Or rather Einsteinian, I don't think Newtonian gravity predicts gravitational lensing? Sure it does, but only half as strong as GR. Ah yes, that's right. I believe that's why the 1919 eclipse data is actually somewhat equivocal, despite catapulting Einstein to fame. (And someone predicted black holes way before Einstein, too, on the basis of Newtonian gravity and the measurement of c - although without realising the full implications ... Mitchell???). Mind you, I think my correction above is still pertinent - that is, it's still truer to say that dark matter is what results when gravity is not modified (pure *Einsteinian*). Dark matter would be implied by the same observations even assuming Newtonian gravity. Just the amount would be different. I don't know if Fritz Zwicky even used relativistic calculations of rotation curves of galaxies to infer dark matter - it wouldn't have been necessary since the motions are not that fast. OK. Incidentally I met Zwicky at a party once and he regalled me with the story of how he and a NACA team had actually beaten the Russians into space by launching an artificial satellite *before* Sputnik. When I expressed surprise that I had never heard of this satellite, he explained that it was launched from a B-50 flying at 50kft over the equator using a two stage rocket. When the second stage reached it's apogee, it fired a shaped charge which sent a molten mass of metal into orbit around the Earth. Seriously?! -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
On 12/2/2013 10:19 PM, LizR wrote: On 3 December 2013 11:55, meekerdb meeke...@verizon.net mailto:meeke...@verizon.net wrote: On 12/2/2013 1:14 PM, LizR wrote: On 2 December 2013 20:14, meekerdb meeke...@verizon.net mailto:meeke...@verizon.net wrote: On 12/1/2013 7:35 PM, LizR wrote: On 2 December 2013 16:16, Richard Ruquist yann...@gmail.com mailto:yann...@gmail.com wrote: MOND is an alternative explanation that replaces Dark Matter by modifying gravity. Yes (hence the flippant remark about bolt on extras) Dark Matter results when gravity is not modified. (pure Newtonian) Or rather Einsteinian, I don't think Newtonian gravity predicts gravitational lensing? Sure it does, but only half as strong as GR. Ah yes, that's right. I believe that's why the 1919 eclipse data is actually somewhat equivocal, despite catapulting Einstein to fame. (And someone predicted black holes way before Einstein, too, on the basis of Newtonian gravity and the measurement of c - although without realising the full implications ... Mitchell???). Mind you, I think my correction above is still pertinent - that is, it's still truer to say that dark matter is what results when gravity is not modified (pure /Einsteinian/). Dark matter would be implied by the same observations even assuming Newtonian gravity. Just the amount would be different. I don't know if Fritz Zwicky even used relativistic calculations of rotation curves of galaxies to infer dark matter - it wouldn't have been necessary since the motions are not that fast. OK. Incidentally I met Zwicky at a party once and he regalled me with the story of how he and a NACA team had actually beaten the Russians into space by launching an artificial satellite *before* Sputnik. When I expressed surprise that I had never heard of this satellite, he explained that it was launched from a B-50 flying at 50kft over the equator using a two stage rocket. When the second stage reached it's apogee, it fired a shaped charge which sent a molten mass of metal into orbit around the Earth. Seriously?! We were both a little drunk, but he was serious. I asked if the blob of metal had been tracked in orbit? Zwicky said it was too small to track by radar. So then I asked how they knew it entered orbit. He said they knew because telemetry from the second stage rocket showed that it had fired the shaped charge at the right altitude and right direction. I had not recalled this for many years; the party was in 1963. Consulting the internet (which remembers everything, many of which actually happened) I find that Zwicky wrote a paper about these experiments which differs somewhat from my recollection. http://calteches.library.caltech.edu/1801/1/zwicky.pdf Brent Brent -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
On 30 November 2013 12:04, Telmo Menezes te...@telmomenezes.com wrote: Thanks for the explanations. Ok, I think I now understand why dark matter is the best hypothesis. It is, to date. Neverthless, you would have been quite correct had it been the anomaly in the orbit of Mercury that you were trying to explain, rather than the anomalous rotation of galaxies observed in 1933 by Fritz Zwicky. Pre-Einstein, various theories were advanced to explain the anomalous perihelion advance of Mercury (relative to what Newtonian gravitation predicted it should have been) including hidden matter - an undetected planet (called Vulcan, as Trekkies and Dr Who fans will appreciate) and an odd mass distribution inside the Sun. But in that case, it turned out that the best answer WAS to modify gravity. So far DM has remained the top explanation even as more phenomena involving it have been discovered (garvitational lensing for example). Some of its characteristics are now fairly well measured; its nature remains unexplained... which makes life interesting for particle physicists and cosmologists. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
Liz, There are 7 other repeatable observations explained by dark matter. From wiki-dark matter - 3.1 Galaxy rotation curveshttp://en.wikipedia.org/wiki/Dark_matter#Galaxy_rotation_curves - 3.2 Velocity dispersions of galaxieshttp://en.wikipedia.org/wiki/Dark_matter#Velocity_dispersions_of_galaxies - 3.3 Galaxy clusters and gravitational lensinghttp://en.wikipedia.org/wiki/Dark_matter#Galaxy_clusters_and_gravitational_lensing - 3.4 Cosmic microwave backgroundhttp://en.wikipedia.org/wiki/Dark_matter#Cosmic_microwave_background - 3.5 Sky surveys and baryon acoustic oscillationshttp://en.wikipedia.org/wiki/Dark_matter#Sky_surveys_and_baryon_acoustic_oscillations - 3.6 Type Ia supernovae distance measurementshttp://en.wikipedia.org/wiki/Dark_matter#Type_Ia_supernovae_distance_measurements - 3.7 Lyman-alpha foresthttp://en.wikipedia.org/wiki/Dark_matter#Lyman-alpha_forest - 3.8 Structure formationhttp://en.wikipedia.org/wiki/Dark_matter#Structure_formation On Sun, Dec 1, 2013 at 4:58 PM, LizR lizj...@gmail.com wrote: On 30 November 2013 12:04, Telmo Menezes te...@telmomenezes.com wrote: Thanks for the explanations. Ok, I think I now understand why dark matter is the best hypothesis. It is, to date. Neverthless, you would have been quite correct had it been the anomaly in the orbit of Mercury that you were trying to explain, rather than the anomalous rotation of galaxies observed in 1933 by Fritz Zwicky. Pre-Einstein, various theories were advanced to explain the anomalous perihelion advance of Mercury (relative to what Newtonian gravitation predicted it should have been) including hidden matter - an undetected planet (called Vulcan, as Trekkies and Dr Who fans will appreciate) and an odd mass distribution inside the Sun. But in that case, it turned out that the best answer WAS to modify gravity. So far DM has remained the top explanation even as more phenomena involving it have been discovered (garvitational lensing for example). Some of its characteristics are now fairly well measured; its nature remains unexplained... which makes life interesting for particle physicists and cosmologists. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
Thanks, that's an impressive list. I'd be rather surprised if bolt-on extras to GR can explain all those. On 2 December 2013 12:43, Richard Ruquist yann...@gmail.com wrote: Liz, There are 7 other repeatable observations explained by dark matter. From wiki-dark matter - 3.1 Galaxy rotation curveshttp://en.wikipedia.org/wiki/Dark_matter#Galaxy_rotation_curves - 3.2 Velocity dispersions of galaxieshttp://en.wikipedia.org/wiki/Dark_matter#Velocity_dispersions_of_galaxies - 3.3 Galaxy clusters and gravitational lensinghttp://en.wikipedia.org/wiki/Dark_matter#Galaxy_clusters_and_gravitational_lensing - 3.4 Cosmic microwave backgroundhttp://en.wikipedia.org/wiki/Dark_matter#Cosmic_microwave_background - 3.5 Sky surveys and baryon acoustic oscillationshttp://en.wikipedia.org/wiki/Dark_matter#Sky_surveys_and_baryon_acoustic_oscillations - 3.6 Type Ia supernovae distance measurementshttp://en.wikipedia.org/wiki/Dark_matter#Type_Ia_supernovae_distance_measurements - 3.7 Lyman-alpha foresthttp://en.wikipedia.org/wiki/Dark_matter#Lyman-alpha_forest - 3.8 Structure formationhttp://en.wikipedia.org/wiki/Dark_matter#Structure_formation On Sun, Dec 1, 2013 at 4:58 PM, LizR lizj...@gmail.com wrote: On 30 November 2013 12:04, Telmo Menezes te...@telmomenezes.com wrote: Thanks for the explanations. Ok, I think I now understand why dark matter is the best hypothesis. It is, to date. Neverthless, you would have been quite correct had it been the anomaly in the orbit of Mercury that you were trying to explain, rather than the anomalous rotation of galaxies observed in 1933 by Fritz Zwicky. Pre-Einstein, various theories were advanced to explain the anomalous perihelion advance of Mercury (relative to what Newtonian gravitation predicted it should have been) including hidden matter - an undetected planet (called Vulcan, as Trekkies and Dr Who fans will appreciate) and an odd mass distribution inside the Sun. But in that case, it turned out that the best answer WAS to modify gravity. So far DM has remained the top explanation even as more phenomena involving it have been discovered (garvitational lensing for example). Some of its characteristics are now fairly well measured; its nature remains unexplained... which makes life interesting for particle physicists and cosmologists. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
Can you explain what you mean by 'bolt-on extras to GR'? On Sun, Dec 1, 2013 at 7:18 PM, LizR lizj...@gmail.com wrote: Thanks, that's an impressive list. I'd be rather surprised if bolt-on extras to GR can explain all those. On 2 December 2013 12:43, Richard Ruquist yann...@gmail.com wrote: Liz, There are 7 other repeatable observations explained by dark matter. From wiki-dark matter - 3.1 Galaxy rotation curveshttp://en.wikipedia.org/wiki/Dark_matter#Galaxy_rotation_curves - 3.2 Velocity dispersions of galaxieshttp://en.wikipedia.org/wiki/Dark_matter#Velocity_dispersions_of_galaxies - 3.3 Galaxy clusters and gravitational lensinghttp://en.wikipedia.org/wiki/Dark_matter#Galaxy_clusters_and_gravitational_lensing - 3.4 Cosmic microwave backgroundhttp://en.wikipedia.org/wiki/Dark_matter#Cosmic_microwave_background - 3.5 Sky surveys and baryon acoustic oscillationshttp://en.wikipedia.org/wiki/Dark_matter#Sky_surveys_and_baryon_acoustic_oscillations - 3.6 Type Ia supernovae distance measurementshttp://en.wikipedia.org/wiki/Dark_matter#Type_Ia_supernovae_distance_measurements - 3.7 Lyman-alpha foresthttp://en.wikipedia.org/wiki/Dark_matter#Lyman-alpha_forest - 3.8 Structure formationhttp://en.wikipedia.org/wiki/Dark_matter#Structure_formation On Sun, Dec 1, 2013 at 4:58 PM, LizR lizj...@gmail.com wrote: On 30 November 2013 12:04, Telmo Menezes te...@telmomenezes.com wrote: Thanks for the explanations. Ok, I think I now understand why dark matter is the best hypothesis. It is, to date. Neverthless, you would have been quite correct had it been the anomaly in the orbit of Mercury that you were trying to explain, rather than the anomalous rotation of galaxies observed in 1933 by Fritz Zwicky. Pre-Einstein, various theories were advanced to explain the anomalous perihelion advance of Mercury (relative to what Newtonian gravitation predicted it should have been) including hidden matter - an undetected planet (called Vulcan, as Trekkies and Dr Who fans will appreciate) and an odd mass distribution inside the Sun. But in that case, it turned out that the best answer WAS to modify gravity. So far DM has remained the top explanation even as more phenomena involving it have been discovered (garvitational lensing for example). Some of its characteristics are now fairly well measured; its nature remains unexplained... which makes life interesting for particle physicists and cosmologists. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
Ad hoc modifications to our existing theories. Although it looks like it's actually bolt-on extras to Newtonian gravitation... http://en.wikipedia.org/wiki/MOND On 2 December 2013 14:33, Richard Ruquist yann...@gmail.com wrote: Can you explain what you mean by 'bolt-on extras to GR'? -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
I should have said that by ad hoc I mean with no, or little, theoretical justification. That is, adjusting the threoy to fit the data, but with for no compelling theoretical justification. On 2 December 2013 15:42, LizR lizj...@gmail.com wrote: Ad hoc modifications to our existing theories. Although it looks like it's actually bolt-on extras to Newtonian gravitation... http://en.wikipedia.org/wiki/MOND On 2 December 2013 14:33, Richard Ruquist yann...@gmail.com wrote: Can you explain what you mean by 'bolt-on extras to GR'? -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
MOND is an alternative explanation that replaces Dark Matter by modifying gravity. Dark Matter results when gravity is not modified. (pure Newtonian) IMO John Moffat has a much better mod-gravity theory http://arxiv.org/pdf/gr-qc/0506021.pdf wiki-Moffat: He proposes a variable speed of lighthttp://en.wikipedia.org/wiki/Variable_speed_of_light approach to cosmological http://en.wikipedia.org/wiki/Physical_cosmology problems, which posits that *G http://en.wikipedia.org/wiki/Gravitational_constant*/ *c* is constant through time, but *G* and *c* separately have not been.in the early universe, in which the speed of light was 1030 times faster than its current value. Richard: That would say that the fine structure constant was different in the early universe, which agrees with observations of the Keck telescope. However, more recent observations in the southern hemisphere indicates the the fine structure constant varies monotonically north to south and not as a function of time. I have used those observations to hypothesize that the Calabi-Yau compact space particles are numerable and a basis for computationalism in my string cosmology papers. But he has done much more- read his wiki. On a personal note John Moffat was a consultant one summer in the MIT Lincoln Lab group that I worked in in the late 1960s. But I am not sure it's the same John Moffat. On Sun, Dec 1, 2013 at 9:44 PM, LizR lizj...@gmail.com wrote: I should have said that by ad hoc I mean with no, or little, theoretical justification. That is, adjusting the threoy to fit the data, but with for no compelling theoretical justification. On 2 December 2013 15:42, LizR lizj...@gmail.com wrote: Ad hoc modifications to our existing theories. Although it looks like it's actually bolt-on extras to Newtonian gravitation... http://en.wikipedia.org/wiki/MOND On 2 December 2013 14:33, Richard Ruquist yann...@gmail.com wrote: Can you explain what you mean by 'bolt-on extras to GR'? -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
On 2 December 2013 16:16, Richard Ruquist yann...@gmail.com wrote: MOND is an alternative explanation that replaces Dark Matter by modifying gravity. Yes (hence the flippant remark about bolt on extras) Dark Matter results when gravity is not modified. (pure Newtonian) Or rather Einsteinian, I don't think Newtonian gravity predicts gravitational lensing? IMO John Moffat has a much better mod-gravity theory http://arxiv.org/pdf/gr-qc/0506021.pdf That VSL idea sounds familiar, I may have heard of that before. I would imagine it solves the horizon problem and does away with the need for inflation in the early universe; if he can also sort our dark matter and dark energy he's doing rather well, all he needs after that is an acid test that will distinguish his theory from GR (much as the 1919 eclipse was supposed to have been the acid test for GR vs Newtonian gravity) and he can claim his Nobel (if he hasn't got one already). In fact, I'm fairly sure we have the Magueijo book somewhere. (When do I get my ansible?) -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
Moffat even does away with renormalization. The acid test was to be the fine structure constant being time dependent. But that was not repeatable for a south hemisphere telescope whose name I forget. The two Keck Telescopes were built at Litton ITEK in Lexington, MA where I worked for a few years. They had cornered the market for spaceborne spy satellites. But after the Berlin Wall came down the US govt decided they did not need ITEK any more and ITEK was sold to Perkin Elmer who screwed up the Hubble Space telescope. Most of us lost our jobs instead of moving to Connecticut. It was the last physics research job I had. On Sun, Dec 1, 2013 at 10:35 PM, LizR lizj...@gmail.com wrote: On 2 December 2013 16:16, Richard Ruquist yann...@gmail.com wrote: MOND is an alternative explanation that replaces Dark Matter by modifying gravity. Yes (hence the flippant remark about bolt on extras) Dark Matter results when gravity is not modified. (pure Newtonian) Or rather Einsteinian, I don't think Newtonian gravity predicts gravitational lensing? IMO John Moffat has a much better mod-gravity theory http://arxiv.org/pdf/gr-qc/0506021.pdf That VSL idea sounds familiar, I may have heard of that before. I would imagine it solves the horizon problem and does away with the need for inflation in the early universe; if he can also sort our dark matter and dark energy he's doing rather well, all he needs after that is an acid test that will distinguish his theory from GR (much as the 1919 eclipse was supposed to have been the acid test for GR vs Newtonian gravity) and he can claim his Nobel (if he hasn't got one already). In fact, I'm fairly sure we have the Magueijo book somewhere. (When do I get my ansible?) -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
On 12/1/2013 7:35 PM, LizR wrote: On 2 December 2013 16:16, Richard Ruquist yann...@gmail.com mailto:yann...@gmail.com wrote: MOND is an alternative explanation that replaces Dark Matter by modifying gravity. Yes (hence the flippant remark about bolt on extras) Dark Matter results when gravity is not modified. (pure Newtonian) Or rather Einsteinian, I don't think Newtonian gravity predicts gravitational lensing? Sure it does, but only half as strong as GR. Brent IMO John Moffat has a much better mod-gravity theory http://arxiv.org/pdf/gr-qc/0506021.pdf That VSL idea sounds familiar, I may have heard of that before. I would imagine it solves the horizon problem and does away with the need for inflation in the early universe; if he can also sort our dark matter and dark energy he's doing rather well, all he needs after that is an acid test that will distinguish his theory from GR (much as the 1919 eclipse was supposed to have been the acid test for GR vs Newtonian gravity) and he can claim his Nobel (if he hasn't got one already). In fact, I'm fairly sure we have the Magueijo book somewhere. (When do I get my ansible?) -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
On Wed, Nov 27, 2013 at 5:03 PM, Jesse Mazer laserma...@gmail.com wrote: Dark matter behaves pretty convincingly like large clumps of matter that, aside from not interacting with normal matter via non-gravitational forces, obeys the same sort of dynamical laws as any other form of matter, see the following for a good quick summary (note particularly the stuff about the colliding galaxy clusters whose dark matter halos seemed to outshoot the position of the visible clusters themselves, since the visible matter like stars is slowed down via friction with gas and dust during the collision, but friction is an electromagnetic interaction so dark matter should be impervious to it): http://scienceblogs.com/startswithabang/2010/06/24/convincing-a-young-scientist-t/ Thanks Jesse, very nice article. On Wed, Nov 27, 2013 at 7:40 AM, Telmo Menezes te...@telmomenezes.com wrote: Hi all, Honest question: isn't dark matter a fancy name for failed predictions? Cheers, Telmo. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
On Fri, Nov 29, 2013 at 4:57 AM, John Clark johnkcl...@gmail.com wrote: On Wed, Nov 27, 2013 at 9:07 AM, Telmo Menezes te...@telmomenezes.com wrote: if GR requires dark matter to work, and if we can't observe dark matter, doesn't this mean that GR is falsified? If Dark Matter really isn't there then that would indeed falsify General Relativity; but the theory that Dark Matter really isn't there is itself falsified by observations of the Bullet Cluster. John K Clark Thanks John, and also Richard, Brent and Liz. I know my questions are very naive, but the following occurs to me (and I'm sure this has been debated to death by physicists): why is it assumed that this phenomena is caused by some type of matter? As far as I understand, QM hasn't been reconciled with GR gravity. Isn't this + dark matter a sign that there's something fundamental we don't understand yet? Or maybe this is the sense in which dark matter is already used, and I'm worrying too much about the word matter... Telmo. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
On Fri, Nov 29, 2013 at 6:18 AM, Telmo Menezes te...@telmomenezes.comwrote: why is it assumed that this phenomena is caused by some type of matter? [...] and I'm worrying too much about the word matter... Observations of the Bullet Cluster indicate that whatever this dark stuff is it has inertia and moves much more slowly than light, so it must have a rest mass and it must both produce gravity and be effected by it. To a physicist anything that has those properties is matter even if it's dark, that is to say you can't see it because it is not effected by electromagnetic waves. John K Clark -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
Does the Bullet cluster display any of the characteristics expected of a Dark-Matter-less galaxy such as a spinning galaxy blowing apart.? On Fri, Nov 29, 2013 at 3:18 PM, John Clark johnkcl...@gmail.com wrote: On Fri, Nov 29, 2013 at 6:18 AM, Telmo Menezes te...@telmomenezes.comwrote: why is it assumed that this phenomena is caused by some type of matter? [...] and I'm worrying too much about the word matter... Observations of the Bullet Cluster indicate that whatever this dark stuff is it has inertia and moves much more slowly than light, so it must have a rest mass and it must both produce gravity and be effected by it. To a physicist anything that has those properties is matter even if it's dark, that is to say you can't see it because it is not effected by electromagnetic waves. John K Clark -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
On Fri, Nov 29, 2013 at 3:31 PM, Richard Ruquist yann...@gmail.com wrote: Does the Bullet cluster display any of the characteristics expected of a Dark-Matter-less galaxy such as a spinning galaxy blowing apart.? For years people have tried to modify the law of gravitation so that it is consistent with what we see with our telescopes but it just doesn't work. If you observe the Bullet Cluster what you see is 2 clusters colliding and the regular matter that we can see staying in the center just as we'd expect regular matter to do and the Dark Matter (detected by gravitational lensing) remained spread out just as you'd expect Dark Matter to do. There is no way modifying gravity can explain that. And in addition, if you tinker with gravity so that galaxies like our own Milky Way hold together and behave as they should then galactic clusters like the Local group don't behave as we see them do. And if you tinker with gravity in another way so that galactic clusters behave as they do in our telescopes then individual galaxies don't. But if you invoke Dark Matter then everything comes out fine. John K Clark -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
On 11/29/2013 3:18 AM, Telmo Menezes wrote: On Fri, Nov 29, 2013 at 4:57 AM, John Clark johnkcl...@gmail.com wrote: On Wed, Nov 27, 2013 at 9:07 AM, Telmo Menezes te...@telmomenezes.com wrote: if GR requires dark matter to work, and if we can't observe dark matter, doesn't this mean that GR is falsified? If Dark Matter really isn't there then that would indeed falsify General Relativity; but the theory that Dark Matter really isn't there is itself falsified by observations of the Bullet Cluster. John K Clark Thanks John, and also Richard, Brent and Liz. I know my questions are very naive, but the following occurs to me (and I'm sure this has been debated to death by physicists): why is it assumed that this phenomena is caused by some type of matter? First, that isn't just assumed. Other theories to explain it have been put forward, e.g. modifications of GR. But so far they have all been invalidated by observations, whereas the hypothesis that it is some kind of matter that interacts only (or almost only) via gravity has survived an increasing variety of observations. As far as I understand, QM hasn't been reconciled with GR gravity. Isn't this + dark matter a sign that there's something fundamental we don't understand yet? There's certainly somethings we don't understand yet. Whether dark matter is 'fundamental', in the sense that QM and GR are fundamentally in conflict, is possible but not supported by any data yet. Brent Or maybe this is the sense in which dark matter is already used, and I'm worrying too much about the word matter... Telmo. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
My question has nothing to do with modyfying gravity On Fri, Nov 29, 2013 at 3:58 PM, John Clark johnkcl...@gmail.com wrote: On Fri, Nov 29, 2013 at 3:31 PM, Richard Ruquist yann...@gmail.comwrote: Does the Bullet cluster display any of the characteristics expected of a Dark-Matter-less galaxy such as a spinning galaxy blowing apart.? For years people have tried to modify the law of gravitation so that it is consistent with what we see with our telescopes but it just doesn't work. If you observe the Bullet Cluster what you see is 2 clusters colliding and the regular matter that we can see staying in the center just as we'd expect regular matter to do and the Dark Matter (detected by gravitational lensing) remained spread out just as you'd expect Dark Matter to do. There is no way modifying gravity can explain that. And in addition, if you tinker with gravity so that galaxies like our own Milky Way hold together and behave as they should then galactic clusters like the Local group don't behave as we see them do. And if you tinker with gravity in another way so that galactic clusters behave as they do in our telescopes then individual galaxies don't. But if you invoke Dark Matter then everything comes out fine. John K Clark -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
For years people have tried to modify the law of gravitation so that it is consistent with what we see with our telescopes but it just doesn't work. If you observe the Bullet Cluster what you see is 2 clusters colliding and the regular matter that we can see staying in the center just as we'd expect regular matter to do and the Dark Matter (detected by gravitational lensing) remained spread out just as you'd expect Dark Matter to do. There is no way modifying gravity can explain that. And in addition, if you tinker with gravity so that galaxies like our own Milky Way hold together and behave as they should then galactic clusters like the Local group don't behave as we see them do. And if you tinker with gravity in another way so that galactic clusters behave as they do in our telescopes then individual galaxies don't. But if you invoke Dark Matter then everything comes out fine. John K Clark On Fri, Nov 29, 2013 at 10:26 PM, meekerdb meeke...@verizon.net wrote: First, that isn't just assumed. Other theories to explain it have been put forward, e.g. modifications of GR. But so far they have all been invalidated by observations, whereas the hypothesis that it is some kind of matter that interacts only (or almost only) via gravity has survived an increasing variety of observations. As far as I understand, QM hasn't been reconciled with GR gravity. Isn't this + dark matter a sign that there's something fundamental we don't understand yet? There's certainly somethings we don't understand yet. Whether dark matter is 'fundamental', in the sense that QM and GR are fundamentally in conflict, is possible but not supported by any data yet. Brent John and Brent, Thanks for the explanations. Ok, I think I now understand why dark matter is the best hypothesis. Cheers Telmo. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
On Wed, Nov 27, 2013 at 9:07 AM, Telmo Menezes te...@telmomenezes.comwrote: if GR requires dark matter to work, and if we can't observe dark matter, doesn't this mean that GR is falsified? If Dark Matter really isn't there then that would indeed falsify General Relativity; but the theory that Dark Matter really isn't there is itself falsified by observations of the Bullet Cluster. John K Clark -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
Dark Matter is required for GR to predict that galaxies do not fly apart Richard On Wed, Nov 27, 2013 at 7:40 AM, Telmo Menezes te...@telmomenezes.comwrote: Hi all, Honest question: isn't dark matter a fancy name for failed predictions? Cheers, Telmo. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
On Wed, Nov 27, 2013 at 3:04 PM, Richard Ruquist yann...@gmail.com wrote: Dark Matter is required for GR to predict that galaxies do not fly apart Richard Hi Richard, Thanks. I didn't express myself clearly. What I mean is: if GR requires dark matter to work, and if we can't observe dark matter, doesn't this mean that GR is falsified? It seems to predict the existence of something that is not there... Telmo. On Wed, Nov 27, 2013 at 7:40 AM, Telmo Menezes te...@telmomenezes.com wrote: Hi all, Honest question: isn't dark matter a fancy name for failed predictions? Cheers, Telmo. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
Telmo Menezes te...@telmomenezes.com viahttp://support.google.com/mail/bin/answer.py?hl=enanswer=1311182ctx=mail googlegroups.com 9:07 AM (12 minutes ago) to everything-list On Wed, Nov 27, 2013 at 3:04 PM, Richard Ruquist yann...@gmail.com wrote: Dark Matter is required for GR to predict that galaxies do not fly apart Richard Hi Richard, Thanks. I didn't express myself clearly. What I mean is: if GR requires dark matter to work, and if we can't observe dark matter, doesn't this mean that GR is falsified? It seems to predict the existence of something that is not there... Telmo. No. Dark matter and energy are clearly there whether or not we know what particles they are made of. There are several observations/measurements that indicate that the universe is flat. The existence of dark matter and energy is completely consistent with them. On Wed, Nov 27, 2013 at 9:07 AM, Telmo Menezes te...@telmomenezes.comwrote: On Wed, Nov 27, 2013 at 3:04 PM, Richard Ruquist yann...@gmail.com wrote: Dark Matter is required for GR to predict that galaxies do not fly apart Richard Hi Richard, Thanks. I didn't express myself clearly. What I mean is: if GR requires dark matter to work, and if we can't observe dark matter, doesn't this mean that GR is falsified? It seems to predict the existence of something that is not there... Telmo. On Wed, Nov 27, 2013 at 7:40 AM, Telmo Menezes te...@telmomenezes.com wrote: Hi all, Honest question: isn't dark matter a fancy name for failed predictions? Cheers, Telmo. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
Dark matter behaves pretty convincingly like large clumps of matter that, aside from not interacting with normal matter via non-gravitational forces, obeys the same sort of dynamical laws as any other form of matter, see the following for a good quick summary (note particularly the stuff about the colliding galaxy clusters whose dark matter halos seemed to outshoot the position of the visible clusters themselves, since the visible matter like stars is slowed down via friction with gas and dust during the collision, but friction is an electromagnetic interaction so dark matter should be impervious to it): http://scienceblogs.com/startswithabang/2010/06/24/convincing-a-young-scientist-t/ On Wed, Nov 27, 2013 at 7:40 AM, Telmo Menezes te...@telmomenezes.comwrote: Hi all, Honest question: isn't dark matter a fancy name for failed predictions? Cheers, Telmo. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
On 11/27/2013 4:40 AM, Telmo Menezes wrote: Hi all, Honest question: isn't dark matter a fancy name for failed predictions? No. Although it is dark it can be 'seen' by gravitational lensing and by its effect on the motion of luminous matter. Brent -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
Re: doesn't dark matter falsify general relativity?
On 28 November 2013 03:07, Telmo Menezes te...@telmomenezes.com wrote: Thanks. I didn't express myself clearly. What I mean is: if GR requires dark matter to work, and if we can't observe dark matter, doesn't this mean that GR is falsified? It seems to predict the existence of something that is not there... Only to the extent that beta decay invalidates quantum theory, I would say. The least unknowns approach suggests that GR - observed to be correct in all situations where it can be measured - is correct, and dark matter is a form of matter (or at least a source of gravity) that we can't detect. Or (like the neutrino) that we can't detect yet. -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
