1 centillion light years away

Sylvia Else wrote:

My objection to dark matter and dark energy is they get into epicycles.
They are not observed yet they are proposed to explain problems with
edge cases.

Our galaxy is rotating at a rate that should cause it to come apart
given the mass that we can see. This is hardly an edge case. We need to
be able to explain either how the galaxy stays together despite its mass
being too low, or find a way to allow its mass to be high enough without
the matter getting in the way of the things we can see.

Let's see if I understand the issue correctly:

Sol is in orbit around the center of mass of the galaxy, isn't it?
There would be enough noise in the orbit to make it only roughly
eliptical but it does orbit. The galatic rotation is the average of all
of the stars and other matter that can be detected in the EM bands.
Something has to have enough mass for all of those orbits to occur.

The galatic arms are not so much bands of higher density of stars but
bands of newer brighter stars. The arms could be formed by a
statistical feature of the orbits of gas clouds plus some effect that
the general galactic magnetic field has on the ionized gas. The part I
don't get here is if the galactic magnetic field accelerates ions that
then become a part of stars that momentum should be a part of the
stellar masses so star should migrate outwards. Maybe ions form shock
waves when they encounter uncharged gas clouds and those shock waves are
the main source of matter for the clouds.

Either there's matter that's not detectable in the EM bands and
therefore the majority of the matter in the galaxy and hence the
universe is in a form that does not interact with EM (dark matter) or
the current estimates of galatic masses are almost two orders of
magnitude too low using matter that does interact.

How large could a black hole or neutron star be without being visible at
over a parsec? Far enough out and you'd need to see it indirectly by
apparent motion of the stars behind it because of gravitational
deflection. How old would a black hole need to be to be invisible? If
I understand the issue correctly the problem is the age and number of
such invisible large objects. There would have to be a lot more of them
than stars to account for the visible mass and that would introduce far
more noise in stellar galactic orbits than has been observed. Therefore
the extra mass has to be wildly disbursed not in black holes.

Black holes and neutron stars do not carry enough net charge to matter
in that sense but their gravititional field is so strong that objects
descending towards them have a lot of electromagnetic interaction. They
should glow from what boils down to descent friction. The spectra of
stars observed do not match this pattern therefore such objects are not
the majority of stars. Such objects should glow just from the galatic
background gas (?). There should b emany and none are seen. Even the
oldest should be visible from introducing a lot more noise in stellar
orbits - A hundred times as many massive objects would mean orders of
magnitude more close enounters would mean orders of magnitude more stars
with rogue orbits.

None of the expected effects of a lot of black hole or neutron stars
have been observed therefore there are not 20-100 times as much mass in
these objects as in stars. There is a lot of gravitational mass to be
accounted for anyways based on stellar orbits. Therefore the missing
mass is widely dispursed.

As near as I can tell that's the main starting point of the evidence and
the starting point of the line of reasoning.

On 14/07/2010 1:29 AM, Doug Freyburger wrote:


As near as I can tell that's the main starting point of the evidence and
the starting point of the line of reasoning.

Seems a reasonable summary, to which I'd only add that the missing mass
cannot be within any stellar systems whose orbital mechanics are known
are known, because it would affect planetary orbits. Alternatively, it
would have to be a kind of mass whose gravitional effects occur only at
large distances (I'm highly sceptical of that, and it would require
considerable rejigging of the theoretical framework, but it's not
impossible). The theory of gravity may just be wrong over large distances.

Sylvia.

Sylvia Else wrote:
On 14/07/2010 1:29 AM, Doug Freyburger wrote:


As near as I can tell that's the main starting point of the evidence and
the starting point of the line of reasoning.

Seems a reasonable summary, to which I'd only add that the missing mass
cannot be within any stellar systems whose orbital mechanics are known
are known, because it would affect planetary orbits. Alternatively, it
would have to be a kind of mass whose gravitional effects occur only at
large distances (I'm highly sceptical of that, and it would require
considerable rejigging of the theoretical framework, but it's not
impossible). The theory of gravity may just be wrong over large distances.

Sylvia.


So for so-called nonbaryonic dark matter what is it supposed to be composed of
other than neutrinos? Other leptons? Can't be electrons. And why is it not
readily observed if it's supposed to be rampant all over the universe compared
to ordinary matter. Isn't disperal a key requirement if it's assumed to be in
such abundance? I'm not ready to buy into the fiction that it's the
speculative axions or another as yet unknown "supersymmetric particle" that
also lies outside the standard model.

How would such an abundance of dark matter effect particle collision
experiments and the standard model? Wouldn't/shouldn't we see more lepton
creation?

It may not be so radical to believe the theory of gravity may just be wrong
over large distances. Or that maybe our presumptions on the uniformity of
space-time are wrong. Something is clearly missing. Give credit to Newton for
rejecting the idea of an "aether" early on:

[ from http://en.wikipedia.org/wiki/Luminiferous_aether ]

"Christiaan Huygens, prior to Newton, had hypothesized that light was a wave
propagating through an aether, but Newton rejected this idea. The main reason
for his rejection stemmed from the fact that both men could apparently only
envision light to be a longitudinal wave, like sound and other mechanical
waves in fluids. However, longitudinal waves by necessity have only one form
for a given propagation direction, rather than two polarizations as in a
transverse wave, and thus they were unable to explain the phenomenon of
birefringence, where two polarizations of light are refracted differently by a
crystal. Instead, Newton preferred to imagine non-spherical particles, or
"corpuscles", of light with different "sides" that give rise to birefringence.
A further reason why Newton rejected light as waves in a medium was because
such a medium would have to extend everywhere in space, and would thereby
"disturb and retard the Motions of those great Bodies" (the planets and
comets) and thus "as it [light's medium] is of no use, and hinders the
Operation of Nature, and makes her languish, so there is no evidence for its
Existence, and therefore it ought to be rejected."

Hear hear....

Dave

On 14/07/2010 12:45 PM, David Spain wrote:

So for so-called nonbaryonic dark matter what is it supposed to be
composed of other than neutrinos? Other leptons? Can't be electrons. And
why is it not readily observed if it's supposed to be rampant all over
the universe compared to ordinary matter. Isn't disperal a key
requirement if it's assumed to be in such abundance? I'm not ready to
buy into the fiction that it's the speculative axions or another as yet
unknown "supersymmetric particle" that also lies outside the standard
model.

It wouldn't be readily observed if its only interactions were
gravitational. It would show up in unexpectedly high red shifts of
distant galaxies (we'd be seeing them earlier on, when the missing mass
had had less time to slow them down, but I believe this is actually
opposite to what is observed), and higher than expected rotation rates
of indiviual galaxies which is what we do see.

However, if something interacted only gravitationally, it would be
difficult to explain its exclusion for within stella systems.

As for what it's composed of, that's really putting the cart before the
horse. The Universe isn't required to be constructed from the elements
we currently consider to exist.

So you start by constructing a theory that explains observations, and
then try to attach physical meanings to the terms in the theory. If, not
withstanding the objection above, a theory that described observations
contained a term that could only reasonably be viewed as a homogenous
'stuff' pervading the Universe, then that's where you'd be at pending
further experiments and observations.

Sylvia.

Sylvia Else ) writes:
On 14/07/2010 12:45 PM, David Spain wrote:

So for so-called nonbaryonic dark matter what is it supposed to be
composed of other than neutrinos? Other leptons? Can't be electrons. And
why is it not readily observed if it's supposed to be rampant all over
the universe compared to ordinary matter. Isn't disperal a key
requirement if it's assumed to be in such abundance? I'm not ready to
buy into the fiction that it's the speculative axions or another as yet
unknown "supersymmetric particle" that also lies outside the standard
model.

It wouldn't be readily observed if its only interactions were
gravitational. It would show up in unexpectedly high red shifts of
distant galaxies (we'd be seeing them earlier on, when the missing mass
had had less time to slow them down, but I believe this is actually
opposite to what is observed), and higher than expected rotation rates
of indiviual galaxies which is what we do see.

However, if something interacted only gravitationally, it would be
difficult to explain its exclusion for within stella systems.

I believe the usual explanation is that its density is too low to produce
perceptible effects (which would of course have to be
gravitational--a set of rotation-curve anomalies for the planets).

As an aside, there are a number of theoretical candidates for dark matter,
and the DAMA group in Italy claims to have seen the signature of one kind
in observations over the last few years. (They certainly have a signal
from *something*.)


As for what it's composed of, that's really putting the cart before the
horse. The Universe isn't required to be constructed from the elements
we currently consider to exist.

So you start by constructing a theory that explains observations, and
then try to attach physical meanings to the terms in the theory. If, not
withstanding the objection above, a theory that described observations
contained a term that could only reasonably be viewed as a homogenous
'stuff' pervading the Universe, then that's where you'd be at pending
further experiments and observations.

Which are currently in progress.

--John Park

David Spain wrote:
Sylvia Else wrote:

Seems a reasonable summary, to which I'd only add that the missing mass
cannot be within any stellar systems whose orbital mechanics are known
are known, because it would affect planetary orbits ...

If I read the explanations correctly the dark matter would need to be
dispursed close to evenly within stellar systems but not close to
evenly between galaxies. That leaves a lot of middle intragalactic
distance ranges where the dispursement doesn't need to be all that even.

What I don't get is why it has to end up even anyway near Sol. If it
interacts by gravity there should be plenty that is gravitationally
bound to Sol so it should follow a density rule AU-to-AU but planetary
orbits do not suggest that. So the field needs to be fairly uniform
across local interstellar space. How would such uniformity come about?
It should vary randomly within a galaxy and that would reduce the
stability of planetary orbits.

The theory of gravity may just be wrong over large distances.

General relativity corrected edge cases of Newtonian gravity. Edge
case correction has already happened in science.

There's also the possibility that our distance estimates are orders of
magnitude higher than the correct distances.

So for so-called nonbaryonic dark matter what is it supposed to be composed of
other than neutrinos? Other leptons? Can't be electrons. And why is it not
readily observed if it's supposed to be rampant all over the universe compared
to ordinary matter. Isn't disperal a key requirement if it's assumed to be in
such abundance? I'm not ready to buy into the fiction that it's the
speculative axions or another as yet unknown "supersymmetric particle" that
also lies outside the standard model.

How would such an abundance of dark matter effect particle collision
experiments and the standard model? Wouldn't/shouldn't we see more lepton
creation?

A particle that does not interact with the electromagnetic force does
not mean it will also not interact with the electro-weak or strong
forces. Neutron stars should usck the stuff up like giant vacuum
cleaners of space and eventually collapse into black holes for the
captured mass. We should see plenty of super nova sized explosions.
Could this be a source for gamma ray bursts?

It may not be so radical to believe the theory of gravity may just be wrong
over large distances. Or that maybe our presumptions on the uniformity of
space-time are wrong. Something is clearly missing. Give credit to Newton for
rejecting the idea of an "aether" early on:

I'll go with the current theory of gravity being wrong as the most
likely based on the very poor model of prior science history.

[ from http://en.wikipedia.org/wiki/Luminiferous_aether ]

"Christiaan Huygens, prior to Newton, had hypothesized that light was a wave
propagating through an aether, but Newton rejected this idea. The main reason
for his rejection stemmed from the fact that both men could apparently only
envision light to be a longitudinal wave, like sound and other mechanical
waves in fluids. However, longitudinal waves by necessity have only one form
for a given propagation direction, rather than two polarizations as in a
transverse wave, and thus they were unable to explain the phenomenon of
birefringence, where two polarizations of light are refracted differently by a
crystal. Instead, Newton preferred to imagine non-spherical particles, or
"corpuscles", of light with different "sides" that give rise to birefringence.
A further reason why Newton rejected light as waves in a medium was because
such a medium would have to extend everywhere in space, and would thereby
"disturb and retard the Motions of those great Bodies" (the planets and
comets) and thus "as it [light's medium] is of no use, and hinders the
Operation of Nature, and makes her languish, so there is no evidence for its
Existence, and therefore it ought to be rejected."

Neither imagined the wave/particle duality of QM.