|
|
|
Thread Tools | Display Modes |
#11
|
|||
|
|||
dark matter hypothesis
In article ,
jacobnavia writes: IF the halo is spherical THEN the study is right. If the halo is NOT spherical but follows the plane of the milky way, i.e. most dead stars are in the galaxy plane and WITHIN the galaxy, that study proves nothing. Aren't there also microlensing studies towards the Galactic bulge? Now, most stars that go supernovae have non-symmetrical explosions that could propel their "dead" corpses in random directions, but the galaxy's gravity should hold most of them back and keep them within the galaxy plane. How would motion perpendicular to the plane be damped out? -- Help keep our newsgroup healthy; please don't feed the trolls. Steve Willner Phone 617-495-7123 Cambridge, MA 02138 USA |
#12
|
|||
|
|||
dark matter hypothesis
In article ,
Martin Brown writes: A Unifying Theory of Dark Energy and Dark Matter: Negative Masses and Matter Creation within a Modified =CE=9B CDM Framework https://arxiv.org/abs/1712.07962 Arxiv link but now also in A&A'. It makes some testable predictions. Paper link is at https://www.aanda.org/articles/aa/fu...a32898-18.html A&A site was flaky the last day or two, but eventually it served the paper. As I wrote on sci.astro, the paper seems highly unconventional but mathematically consistent. It requires _two_ unconventional hypotheses -- existence of negative mass and continuous creation of it -- so skepticism on that basis is warranted. -- Help keep our newsgroup healthy; please don't feed the trolls. Steve Willner Phone 617-495-7123 Cambridge, MA 02138 USA |
#13
|
|||
|
|||
dark matter hypothesis
[[Mod. note -- This article arived in my moderation mailbox with a
number of garbled non-ASCII characters, and many excessively-long lines. I have "tidied up" and reformatted the text; my apologies to all if I've garbled the author's intended meanings. Memo to all newsgroup participants: Usenet isn't fully 8-bit-clean, so it's much safer to restrict your postings to plain ASCII. Notably, avoid "smart quotes" -- they are almost always garbled somewhere before the moderators ever see your submission. -- jt]] 1:13 AMMartin Brown At the risk of opening up a new can of worms what do people think of the new paper from Jamie Farnes at Oxford which seeks to unite dark energy and dark matter as a negative mass fluid filling all of empty space (if I have understood his paper correctly). It seems to work... title: A Unifying Theory of Dark Energy and Dark Matter: Negative Masses and Matter Creation within a Modified =CE=9B CDM Framework https://arxiv.org/abs/1712.07962 Arxiv link but now also in A&A'. It makes some testable predictions. -- Regards, Martin Brown. For what my opinion is worth, I'm glad to see it. I've long been of the opinion that looking for exotic matter or applying modifications to GR were futile. They both ignore published work by W. Israel, H. Sato, K. Maeda among others whose work could potentially be generalized to explain Dark Matter. If we consider that gravity is actually a configuration of space time we must wonder what types of relevant physics we can expect from other types of configurations. And most especially when two different types abut one another, as when expanding Voids interact with stationary matter structures and their associated gravitational fields. In other words when two different metrics are involved. I'm particularly encouraged by this: "It seems that the proposed negative mass fluid can be modelled as either matter or vacuum energy. It has previously been proposed that space-time arises as a form of large-scale condensate of more fundamental objects, that are typically of an unknown nature (e.g. Liberati & Maccione 2014). One could therefore speculate that the negative masses could be interpretable as a quantised form of energy associated with space-time itself". That, _that energy_, is natural to spacetime in the absence of matter. That matter inhibits this energy by its presence. Furthermore, H.Sato and K. Maeda (here) Humitaka Sato Kei-ichi Maeda Progress of Theoretical Physics, Volume 70, Issue 1, 1 July 1983, Pages 119--127, https://doi.org/10.1143/PTP.70.119 offer an idea whereby expansion of a Void causes matter to cluster along the void perimeter and ultimately to form structures via gravitational collapse. With these ideas and Israel's formalism (snowplow effect of expanding space time metric during a supernova) we could ask if: matter structures are, in effect, 'confined' to the filaments because of expanding Voids and cannot escape that confinement? can enough centrifugal acceleration be imparted to disrupt structure? that is : can stars in the outer galaxy even leave bound structure without giving up their energy and "falling back" ? if voids are constraints and they didn't exist would galaxies be larger in breadth? And would their outer components then follow Newtonian mechanics? are DM and DE two sides of the same phenomenon? (To me that seems most plausible, especially when the expansion is accelerating.) Ultimately I don't like the idea of negative mass unless it is in the idea of Dirac's anti electron. That is, more like a "hole" in a sea of normal mass. Also I wonder if negative mass is electromagnetically responsive. I'm more inclined towards any theory explaining the Dark phenomena that invokes, or at least recognizes "metric confinement". Brad |
#14
|
|||
|
|||
dark matter hypothesis
On Thu, 06 Dec 2018, Martin Brown wrote:
new paper from Jamie Farnes at Oxford which seeks to unite dark energy and dark matter as a negative mass fluid filling all of empty space Unimaginative. Dark energy & dark matter are just quantifications of the discrepancy between physical law and our models of it. I prefer a dimensional interpretation where additional dimensions have as-yet unmodelled qualities like "scale" or "Mach's Law". Try explaining colors to a totally color-blind person to get a glimpse of this task. |
#15
|
|||
|
|||
dark matter hypothesis
[[Mod. note -- My apologies for the delay in processing this article,
which was submitted on 2018-12-08. -- jt]] In article , Steve Willner writes: In article , jacobnavia writes: IF the halo is spherical THEN the study is right. If the halo is NOT spherical but follows the plane of the milky way, i.e. most dead stars are in the galaxy plane and WITHIN the galaxy, tha= t study proves nothing. Aren't there also microlensing studies towards the Galactic bulge? Yes, including some by the MACHO collaboration. Now, most stars that go supernovae have non-symmetrical explosions that could propel their "dead" corpses in random directions, but the galaxy'= s gravity should hold most of them back and keep them within the galaxy plane. How would motion perpendicular to the plane be damped out? I think he is saying that while supernovae might cause stellar remnants to move in any direction, the gravity of the galaxy would cause them to concentrate in the plane. (I'm just explaining what I think the original poster meant.) |
#16
|
|||
|
|||
dark matter hypothesis
[[Mod. note --
My apologies for the delay in processing this article, which the author submitted on 2018-12-09. -- jt]] On 12/8/2018 7:38 PM, Steve Willner wrote: In article , jacobnavia writes: IF the halo is spherical THEN the study is right. If the halo is NOT spherical but follows the plane of the milky way, i.e. most dead stars are in the galaxy plane and WITHIN the galaxy, that study proves nothing. Aren't there also microlensing studies towards the Galactic bulge? Now, most stars that go supernovae have non-symmetrical explosions that could propel their "dead" corpses in random directions, but the galaxy's gravity should hold most of them back and keep them within the galaxy plane. How would motion perpendicular to the plane be damped out? If they oscillate up and down the plane, then each time they go through the plane and traverse the denser regions, the elastic collisions with other stars create friction, just like atoms in a gas see friction by the collisions with other atoms (or molecules). This does not seem to be different from what happens before they go supernova, of course.. -- Jos |
#17
|
|||
|
|||
dark matter hypothesis
[[Mod. note -- I apologise for the delay in processing this article,
which the author submitted on 2018-12-09. -- jt]] Steve Willner In article , Martin Brown writes: A Unifying Theory of Dark Energy and Dark Matter: Negative Masses and Matter Creation within a Modified =CE=9B CDM Framework https://arxiv.org/abs/1712.07962 Arxiv link but now also in A&A'. It makes some testable predictions. Paper link is at https://www.aanda.org/articles/aa/fu...a32898-18.html A&A site was flaky the last day or two, but eventually it served the paper. As I wrote on sci.astro, the paper seems highly unconventional but mathematically consistent. It requires _two_ unconventional hypotheses -- existence of negative mass and continuous creation of it -- so skepticism on that basis is warranted. As I understood it he ran simulations. At the end of the paper he states that the negative mass energy could instead be vacuum energy. So my question is...suppose one postulates a field associated with negative mass. Would it be the opposite of a normal gravitational field? Would it take kinetic energy from anything that entered it? Would geodesics diverge? Aren't those qualities associated with an expanding space time metric? Can't we model Voids in such a way? Brad |
#18
|
|||
|
|||
dark matter hypothesis
In article ,
Jos Bergervoet writes: If they oscillate up and down the plane, then each time they go through the plane and traverse the denser regions, the elastic collisions with other stars create friction, just like atoms in a gas see friction by the collisions with other atoms (or molecules). This called "dynamical friction." (I expect Jos knows that, but some readers may not.) The question is how long it takes for this process to damp out the vertical motion. If not very long, why do the thick disk and halo stars still have the orbits they do? This does not seem to be different from what happens before they go supernova, of course.. The progenitors of core-collapse SNe are massive, therefore young, stars and therefore presumably belong to the thin disk population. -- Help keep our newsgroup healthy; please don't feed the trolls. Steve Willner Phone 617-495-7123 Cambridge, MA 02138 USA |
|
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Complete dark matter theory opens door to weight/energy potential(Dark matter is considered to be the top mystery in science today, solved,really.) And more finding on dark matter ebergy science from the 1930's. | [email protected] | Astronomy Misc | 0 | September 14th 08 03:03 AM |
Fritz Zwicky's original dark matter hypothesis | [email protected] | Astronomy Misc | 2 | May 2nd 05 04:33 PM |
Robert Foot's mirror matter hypothesis relevant to dark accelerators? Murray 2003.03.30 | Rich Murray | Astronomy Misc | 1 | March 31st 05 10:50 AM |
Robert Foot's mirror matter hypothesis relevant to dark accelerators? Murray 2003.03.30 | Rich Murray | UK Astronomy | 1 | March 31st 05 10:50 AM |