question from amateur

Several weeks ago I read or saw on tv that several astronomers had
discovered a huge missing area of space. Would this tie in at all with
the missing matter?

Thus spake Theodora Deski
Several weeks ago I read or saw on tv that several astronomers had
discovered a huge missing area of space. Would this tie in at all with
the missing matter?

No. There are empty spaces between galaxies, and larger spaces between
galaxy clusters. This just seems to be an area of empty space much
larger than normal, perhaps larger than would expected in current
models, but I don't know a reason to think this is impossible. Missing
matter is an underdensity of matter throughout the universe. Current
models believe there is an exotic form of matter, known as Cold Dark
Matter which has been impossible to detect by normal means. That idea is
not universally accepted, but there is a shortage of alternative ideas.

Regards

--
Charles Francis
moderator sci.physics.foundations.
substitute charles for NotI to email

In article ,
(Theodora Deski) writes:

Several weeks ago I read or saw on tv that several astronomers had
discovered a huge missing area of space. Would this tie in at all with
the missing matter?

Not directly.

What you are referring to is a void. These have been known for a long
time, but this one is rather large. By "missing matter" I assume you
mean "dark matter", which is matter which we don't see but infer is
there. In the case of a void, or at least this one, there is probably
almost nothing inside, not even dark matter. So, first, the missing
matter is really dark matter; second, in this case it really is missing
and not dark. So the two things have nothing to do with each other and
the confusion comes from referring to dark matter as missing matter.

On the other hand, one has to think about how such voids formed, and
this depends on the composition of the universe, including dark matter,
so in a very roundabout way the two things are related.

On Aug 30, 3:44 am, (Theodora Deski) wrote:
Several weeks ago I read or saw on tv that several astronomers had
discovered a huge missing area of space. Would this tie in at all with
the missing matter?



Actually, it ties in better with missing theory.

Rob
www.amherst.edu/~rloldershaw

(Theodora Deski) wrote:

Several weeks ago I read or saw on tv that several
astronomers had discovered a huge missing area of
space. Would this tie in at all with the missing
matter?

Hi, Theodora.

When astronomers look at the universe, the most
prominent feature is emptiness, and that emptiness
is "clumpy", with threads and sheets of less empty
areas wrapped through and around great volumes of
more empty areas. The usual analogy is to a
borderless pile of soap bubbles, with the areas
where the bubbles intersect at points and edges
being least empty, the areas where bubbles intersect
at faces being medium empty, and the bubble
interiors being very empty.

What was recently found is analogous to an
unexpectedly large soap bubble, a vast volume of
very empty "interior".

If I understand correctly, even the "missing matter"
(which is matter whose presence we infer by the effects
of its gravity on normal matter and especially on
normal matter's electromagnetic radiation, but can't
detect by any form of electromagnetic radiation that
the "missing" or "dark" matter emits itself) is in
short supply in this new, large, empty area.

It was detected by its failure to accelerate via the
gravity of its missing mass the "cosmic microwave
background radiation" passing through it, correlated
with a lack of certain kinds of visible objects in
the same direction.

Here is a good description of the previous record
holder void, for which lots more is known than for
the current one, because it has been studied longer.

http://www.acceleratingfuture.com/michael/blog/?p=69

xanthian.

"Theodora Deski" wrote in message
...
Several weeks ago I read or saw on tv that several astronomers had
discovered a huge missing area of space. Would this tie in at all with
the missing matter?

No. You have heard a seriously garbled version of this story (that's normal
for TV science news). There is no "missing matter". Models of cosmological
evolution after the Big Bang predict large scale structures that include
large voids where less matter (both dark and baryonic, or "normal") is found
in the form of galaxies. The main difference with the new discovery is, it
is larger than the usual predicted voids. It isn't completely empty either.

No space is missing either...

--
Mike Dworetsky

(Remove pants sp*mbl*ck to reply)

Kent Paul Dolan wrote:
(Theodora Deski) wrote:


Several weeks ago I read or saw on tv that several
astronomers had discovered a huge missing area of
space. Would this tie in at all with the missing
matter?

Here is a good description of the previous record
holder void, for which lots more is known than for
the current one, because it has been studied longer.

http://www.acceleratingfuture.com/michael/blog/?p=69

xanthian.
In your reference article:
The density of the Bootes void: 1.67x10^-29 g/cm^3
is extremely small
but the average density of a galaxy
is also small at: ~1x10^-24 g/cm^3
and the critical density of the Universe necessary
so the expansion rate of the Universe
is just barely sufficient
to prevent a recollapse is: ~1x10^-30 g/cm^3

This all contrasts in an extreme manner
from our local density of ~1 g/cm^3
here on earth.

Richard