Does Dark Matter really exist

On Aug 19, 10:12 am, Double-A wrote:

The problem is that by measuring the speed of stars near the center of
the galaxy with starts further out, they find that the stars further
out are moving faster than they should under the inverse square law of
gravity if they were merely being attracted by a mass at the center.
This means there must me a distribution of mass further out. Since
they can't see it, they call it dark matter.

Dunno if you recollect, but non-Keplerian (the more unitary or
'frisbee-like') rotation of galaxies was discussed here numerous times
in recent years. A spiral galaxy differs from our solar system in one
major respect: The solar system has 99% of its mass concentrated in
the center (in the Sun), obliging the planets to obey the laws of
motion observed by Kepler. But percentage-wise, a galaxy has far more
of its mass spread throughout its periphery, in the spiral arms. Can
you say *Mutual Gravitation*? A galaxy's mass distribution is
naturally gonna make its rotation more unitary and less Keplerian.
Nonetheless, a mysterious, invisible substance, "dark
matter",
has been invoked to explain the anomaly. But wait. There's another,
more
compelling argument for "dark matter": excessive lensing of distant
galaxies, lensing in excess of what their gravitational mass should
allow. As long as
space is deemed a 'void-nothing', *something* has gotta account for
the
excessive lensing, so it might as well be "dark matter".
But what is space is *not* a void-nothing? And
what if gravity is exactly what it appears to be and behaves as: an
_accelerating_ flow of the
spatial medium? Operative word is _accelerating_. An accelerating
flow
imparts momentum to matter, but not to light. Light, being massless,
is gonna
be deflected by *any* flow whether it's accelerating or not. Large-
scale, non-accelerating flows in the intergalactic medium are still
gonna lens light. So the lensing is not "gravitational" lensing but
simple *flow lensing*. No dark matter needed.

So in view of non-Keplerian rotation being attributable to a galaxy's
mass distribution, and excessive lensing being attributed to simple
flow lensing, "dark matter" begins looking more like a solution
without a problem.
oc

"oldcoot" wrote in message
ups.com...
On Aug 19, 10:12 am, Double-A wrote:

The problem is that by measuring the speed of stars near the center of
the galaxy with starts further out, they find that the stars further
out are moving faster than they should under the inverse square law of
gravity if they were merely being attracted by a mass at the center.
This means there must me a distribution of mass further out. Since
they can't see it, they call it dark matter.

Dunno if you recollect, but non-Keplerian (the more unitary or
'frisbee-like') rotation of galaxies was discussed here numerous times
in recent years. A spiral galaxy differs from our solar system in one
major respect: The solar system has 99% of its mass concentrated in
the center (in the Sun), obliging the planets to obey the laws of
motion observed by Kepler. But percentage-wise, a galaxy has far more
of its mass spread throughout its periphery, in the spiral arms. Can
you say *Mutual Gravitation*? A galaxy's mass distribution is
naturally gonna make its rotation more unitary and less Keplerian.
Nonetheless, a mysterious, invisible substance, "dark
matter",
has been invoked to explain the anomaly. But wait. There's another,
more
compelling argument for "dark matter": excessive lensing of distant
galaxies, lensing in excess of what their gravitational mass should
allow. As long as
space is deemed a 'void-nothing', *something* has gotta account for
the
excessive lensing, so it might as well be "dark matter".
But what is space is *not* a void-nothing? And
what if gravity is exactly what it appears to be and behaves as: an
_accelerating_ flow of the
spatial medium? Operative word is _accelerating_. An accelerating
flow
imparts momentum to matter, but not to light. Light, being massless,
is gonna
be deflected by *any* flow whether it's accelerating or not. Large-
scale, non-accelerating flows in the intergalactic medium are still
gonna lens light. So the lensing is not "gravitational" lensing but
simple *flow lensing*. No dark matter needed.

So in view of non-Keplerian rotation being attributable to a galaxy's
mass distribution, and excessive lensing being attributed to simple
flow lensing, "dark matter" begins looking more like a solution
without a problem.


OK, I'll bite, Old Coot. However, nobody to date has established with any
degree of certainty how massive a Black Hole really is. First of all,
because of the nature of the beast, you can't see it. Attempts at measuring
the speed of stars spiraling into them are tenuous at best, because there is
a wall of obstructing stars at the center of the galaxy. So it's a hip shot,
at best. The BH could have consumed half of the Milky Way and we wouldn't
really know it, because we weren't there to see it. So, a BH could contain
the mass of a 100B stars instead of a mere10B. . The present estimate of
stars in our galaxy is 200B stars, so I don't really see a problem there.
You can't conclusively prove your postulation, much less disprove mine.

On Aug 20, 4:01 pm, "Hagar" wrote:

You can't conclusively prove your postulation, much less disprove mine.

True. But to capitulate, you said:

It has also been established that a Supermassive Black Hole resides at the
center of our Milky Way galaxy, and quite possibly at the center of a great majority of other galaxies as well. Now these gigantic black holes can
range in mass size from 105 to 1010 solar masses (that is up to 10 billion average stars). With so much mass concentrated in a ball no larger than our Sun, its gravitational reach should be more than enough to hold together our 50,000LY radius galaxy, without the assistance of that mysterious Dark Matter.

Well, the more massive the central BH, the more 'Keplerian' or "solar
system-like" the rotation should be. That is, the outer orbits should
move correspondingly slower than the innermost ones, just as in the
solar system. But in a spiral galaxy they don't. The whole shebang
rotates more as a unit, or with 'non-Keplerian' rotation. That's why a
mystical gravitational "glue" is postulated, holding the disc into its
more-or-less unitary rotation.

But unlike the solar system which gas 99% of its mass concentrated in
the center (in the Sun), a galaxy has a far greater portion of its
mass spread out peripherially. Thus *mutual gravitation* throughout
the disc should provide the "glue". This would mitigate toward the
central BH's mass being much SMALLER, proportionately, than the Sun's
mass in the solar system.

If you're proposing greater mass for the BH, that should produce "more-
Keplerian" rotation, which is not observed. oc