dark matter.

[clifford wright]

Well we have the following bits of what has been very well described as
"handwavium".
Dark matter, Dark energy, Quintessence. There are possibly a few others by
now.
All these concepts have one thing in common, at least for now. They are
very conveniently unobservable at convenient distances, or in the
laboratory on Earth.
You know sometimes it begins to remind me of Pons and Fleiscmann and UFO's.

Doesn't anyone remember the old dictum that extreme theories require
extreme proofs?
Before cosmologists go around inventing even more "unobservable" matter and
energies they should first be required to disprove ALL alternative
explanations based on already known phenomena.

How convenient for example that "Dark Matter" has the habit of only
existing, in quantity outside galactic disks or main structures of baryonic
matter. So hard to ever get to to examine and NEVER found in your Earthly
experiments.
Overall the point seems to me that it looks like a SCALE effect.
In other words the larger the scale of space looked at the bigger the
effect appears.
Frankly that looks more like the result you would get with a simple
modification to known forces over distances large enough to be significant
in the context of the universe itself.
BTW could someone perhaps enlighten me as to how much of the "acceleration"
forces now postulated are actually required by the acceptance of the "dark
matter" theory. This is something that I have not come across in any
journal lately. After all a more massive universe might well need a force
of expansion to prevent a "big crunch" one day.

======================================= MODERATOR'S COMMENT:
(really better for sci.physics perhaps, but will allow for now.) But let's focus on the actual science such as MOND and other theories and not get too esoteric. -GdM

[Jonathan Thornburg [remove -animal to reply]]

clifford wright <c.c.w...@paradise.net.nz> wrote:
> Well we have the following bits of what has been very well described as
> "handwavium".
> Dark matter, Dark energy, Quintessence. There are possibly a few others by
> now.
> All these concepts have one thing in common, at least for now. They are
> very conveniently unobservable at convenient distances, or in the
> laboratory on Earth.
> You know sometimes it begins to remind me of Pons and Fleiscmann and UFO's.
>

[[...]]

>
> How convenient for example that "Dark Matter" has the habit of only
> existing, in quantity outside galactic disks or main structures of baryonic
> matter. So hard to ever get to to examine and NEVER found in your Earthly
> experiments.

[[...]]

I think you're mistaken -- dark matter *is* predicted to be present
near the Earth, it's just very hard to detect. We know of some forms
of matter which are hard to detect (e.g., neutrinos), so it's not much
of a leap of logic to postulate that there might be others around which
we haven't spotted yet.

[Neutrinos were predicted by Pauli in 1930 on theoretical
grounds. But they're very hard to detect, and weren't
directly observed until 1956. Just about everything you
wrote could apply quite nicely to neutrinos in (say) 1950.]

There are experiments running now which are trying to detect dark matter
in Earth-bound laboratories. There have been a couple of claims of
possible detections, but none which have been solid enough to become
widely accepted by other researchers.

So... there are (at least) two possibilities:
(a) dark matter doesn't exist
(b) dark matter does exist, but the experiments so far haven't been
sensitive enough to clearly detect it above the background noises

The only good way to distinguish between these possibilities is to
run more sensitive experiments. These are in progress now, so stay
tuned for further developments over the coming years.....

--
-- "Jonathan Thornburg [remove -animal to reply]" <jth...@astro.indiana-zebra.edu>
Dept of Astronomy, Indiana University, Bloomington, Indiana, USA
"Space travel is utter bilge" -- common misquote of UK Astronomer Royal
Richard Woolley's remarks of 1956
"All this writing about space travel is utter bilge. To go to the
moon would cost as much as a major war." -- what he actually said

[clifford wright]

"Jonathan Thornburg [remove -animal to reply]"

<jth...@astro.indiana-zebra.edu> wrote in
news:80hmnf...@mid.individual.net:

Ah! But there was good reason for Pauli to pedict the neutrino, nuclear
reactions were NOt balancing and energy had to go somewhere.
"Dark matter" is a "material" postulated in a situation where other,
at least as reasonable explanations, are available.
Also it appears to be (as I said) remarkable by its avoidance of baryonic
matter and all the apparent effects that I am aware of involve scaling
factors that (to me) give strong credence to alternative explanations.
In other words, the bigger the chunk of the Universe, the higher the
proportion of "Dark Matter".
Oh well, I'm getting on a bit now and I haven't got so many years to hang
around to see the experimental results. But at the moment I think that i
might put it up as a bet with some of my old colleagues from auckland
university, along with (IMO) the mythical, detectable "Gravitational
radiation".
Please don't talk too much of "background noise" though, this stuff is
supposed to be about 90% of the mass of the universe. Perhaps it is hard
to detect for the same reason that LIGO doesn't work, but then that makes
current theories of gravity even dodgier!
If you and the guys at LIGO are right my pension may get a bit of a blow.
But so far in the latter case I'm still winning.