The universe is expending.

This is what I know from Discovery channel.
At this time, all the galacies are moving apart at high speed.
And the speed isn't constant,
It actually speeding up (moving faster and faster)
The Discovery Channel does not say why it speeding up.

This is what I thought.
Consider the momentum of a galaxy MV, (mass X velociy)
M=total mass of a galaxy, V=speed of that galaxy.
If M is reducing (mass loss in all Star in the fusion reaction,
where mass are converted into energy)
That is why V have to increase to keep the momentum constant.

But there is a giant black hole in the centre of each galaxy.
Soon or later all the Star will fall into that black hole.
It is at the centre of the black hole where energy are
converted back to mass.
Soon or later the reverse process will take place.
That is the Mass of the galaxy will increase and the speed of
the galaxy will start to slow down.
And the universe will start to compress toward a single point.
When all the galacies are compressed into that single point,
perhaps another Big Bang will happen again.

sooncf wrote:

But there is a giant black hole in the centre of each galaxy.

There's a giant black hole in our galaxy, yes - but I've never heard of your
claim of a black hole being at the centre of *every* galaxy...

=- Brian Dickens, the Netherlands

Brian Dickens replied:
sooncf wrote:


But there is a giant black hole in the centre of each galaxy.


There's a giant black hole in our galaxy, yes - but I've never heard of your
claim of a black hole being at the centre of *every* galaxy...

It may be true for some types of galaxies (hypothetically, I'm not saying
it is), but it's clearly not true for irregulars or globular clusters.

Rich

=- Brian Dickens, the Netherlands

Rich wrote:
It may be true for some types of galaxies (hypothetically, I'm not saying
it is), but it's clearly not true for irregulars or globular clusters.


The case for there being a strong connection betwen galaxy formation
and black holes seems to be growing.
Here's a "popular" report:
http://www.space.com/scienceastronom..._030128-1.html

It's possible that globular clusters might contain lower mass black
holes. There were some reports of the detection of a black hole in
M15. e.g. press release at:
http://www-int.stsci.edu/~marel/m15release.html

However, this claim was later retracted.

replied:
Rich wrote:

It may be true for some types of galaxies (hypothetically, I'm not saying
it is), but it's clearly not true for irregulars or globular clusters.

The case for there being a strong connection betwen galaxy formation
and black holes seems to be growing.
Here's a "popular" report:
http://www.space.com/scienceastronom..._030128-1.html

Although the exact mechanisms are unclear, it seems likely that any
spiral, especially the giant ones, would probably harbor a BH.

It's possible that globular clusters might contain lower mass black
holes. There were some reports of the detection of a black hole in
M15. e.g. press release at:
http://www-int.stsci.edu/~marel/m15release.html

However, this claim was later retracted.

I recall an article about Hubble's discovery of two 'medium' sized black
holes (as I recall several hundred solar masses or thereabouts) and
speculation that they would eventually merge.

But I just don't see irregulars or small globulars in the mix. I tend to
think that stellar collisions are responsible in the dense core of a
large spiral, how else could so much mass accrete? YMMV.

Rich

replied:
Rich wrote:

It may be true for some types of galaxies (hypothetically, I'm not saying
it is), but it's clearly not true for irregulars or globular clusters.

The case for there being a strong connection betwen galaxy formation
and black holes seems to be growing.
Here's a "popular" report:
http://www.space.com/scienceastronom..._030128-1.html

Although the exact mechanisms are unclear, it seems likely that any
spiral, especially the giant ones, would probably harbor a BH.

It's possible that globular clusters might contain lower mass black
holes. There were some reports of the detection of a black hole in
M15. e.g. press release at:
http://www-int.stsci.edu/~marel/m15release.html

However, this claim was later retracted.

I recall an article about Hubble's discovery of two 'medium' sized black
holes (as I recall several hundred solar masses or thereabouts) and
speculation that they would eventually merge.

But I just don't see irregulars or small globulars in the mix. I tend to
think that stellar collisions are responsible in the dense core of a
large spiral, how else could so much mass accrete? YMMV.

Rich

"R" == Rich writes:

R Brian Dickens replied:
sooncf wrote:
But there is a giant black hole in the centre of each galaxy.

There's a giant black hole in our galaxy, yes - but I've never
heard of your claim of a black hole being at the centre of *every*
galaxy...

R It may be true for some types of galaxies (...), but it's clearly
R not true for irregulars or globular clusters.

It seems that there is a massive black hole in the center of most
(all?) large galaxies, spiral or elliptical. Why? It's not clear,
but the formation of central black holes and of galaxies may be tied
together.

Globular clusters clearly contain neutron stars. They almost
certainly contain black holes in or near their centers, unless star
formation during the formation of globular clusters were biased
*against* massive stars (which seems difficult to understand).

--
Lt. Lazio, HTML police | e-mail:
No means no, stop rape. | http://patriot.net/%7Ejlazio/
sci.astro FAQ at http://sciastro.astronomy.net/sci.astro.html

Joseph Lazio replied:
"R" == Rich writes:


R Brian Dickens replied:

sooncf wrote:

But there is a giant black hole in the centre of each galaxy.


There's a giant black hole in our galaxy, yes - but I've never
heard of your claim of a black hole being at the centre of *every*
galaxy...


R It may be true for some types of galaxies (...), but it's clearly
R not true for irregulars or globular clusters.

It seems that there is a massive black hole in the center of most
(all?) large galaxies, spiral or elliptical. Why? It's not clear,
but the formation of central black holes and of galaxies may be tied
together.

Globular clusters clearly contain neutron stars. They almost
certainly contain black holes in or near their centers, unless star
formation during the formation of globular clusters were biased
*against* massive stars (which seems difficult to understand).

Globular clusters tend to have a greate collision rate than spirals,
probably due to their orbits, which are speherical about the center of
gravity rather than aligned about a common axis. They also seem to have
very uniform populations of type II stars, generally of pretty much
the same mass. As a result, some of the collissions will form more
massive stars, known as "blue stragglers". There is an upper limit of
mass to stars in globular clusters and blue stragglers are not only
above the limit, but younger and hotter than the other stars in the
cluster.

http://www.haydenplanetarium.org/hp/...5stelcoll.html
http://www.solstation.com/x-objects/bluestrag.htm

I'd suspect that the same mechanims, or encounters that result in a
close binary could eventually lead to some of these stars acquring
enough mass to form a neutron star. Interestingly, I can't find any
material dealing with this directly, although there is lots which
simply refers to the grater incidence of neutron stars in globular
clusters.

http://www.universetoday.com/am/publ..._binaries.html

This was interesting.

http://universe.gsfc.nasa.gov/press/...sar_skytel.pdf

Hmmm, found this...

http://www-int.stsci.edu/~marel/m15release.html

[...]

Marel led a team that uncovered a black hole in the center of the
globular star cluster M15, 32,000 light-years away in the
constellation Pegasus. His collaborator Joris Gerssen, also of
the Space Telescope Science Institute, pinned down the black hole's
mass at 4,000 times that of our Sun.

In a separate observing program, a team led by Rich, and including
Gebhardt and Luis Ho of the Carnegie Institution of Washington,
found a 20,000-solar-mass black hole in the giant globular cluster
G1, located 70 times farther - 2.2 million light-years away - in
the neighboring Andromeda galaxy. By contrast, stellar-mass black
holes are only a few times the mass of our Sun, and galactic-center
black holes can be millions or billions of times more massive than
our Sun.

"G1 has a total mass of 10 million suns, making it about the most
massive globular cluster known." says Rich. "It also has a very
bright core, so I thought it would be a good place to search for
a massive black hole."

A black hole is an infinitely small and dense region where space
is so tightly warped by gravity that not even light can escape. For
many years, astronomers have known two types -- "supermassive" black
holes at the centers of large galaxies and the so-called "stellar-mass"
black holes that result when a star about 10 times the Sun's mass ends
its life in a supernova explosion. Both types have been detected and
measured.

"There are two main theories of black hole formation," says Gebhardt.
"You could either make the black hole all at once, when the galaxy
is forming, by dumping a lot of material in the middle, or you could
start with a seed black hole that subsequently grows over time. The
observational evidence now points to the idea that you start out
with a small seed black hole." The fact that globular clusters have
these small black holes implies that they are excellent candidates
to act as the seeds for the supermassive black holes that lurk in
the centers of nearly all galaxies.

"The Hubble results add new credibility to the latter scenario,"
says Van Der Marel. "Black holes similar to the ones now found
in globular clusters may have been the building blocks that formed
supermassive black holes."

Previously, X-ray observations from the ROSAT Observatory and
NASA's Chandra Observatory have identified ultra-bright X-ray
sources that could also be interpreted as intermediate-mass black
holes in star-forming galaxies. However, alternative interpretations
for these X-ray sources continue to exist. By contrast, Hubble's
measurements are based on the velocities of stars whirling around
in the dense cores of globular clusters, which yield a direct
measurement of the black hole masses.

The M15 globular star cluster is close enough that individual star
speeds can be measured. By contrast, the G1 observations rely on
measurements of the collective properties of many stars. In either
case, a black hole can be identified by using a common Hubble
black-hole-hunting technique, which searches for a rise in
velocities toward the cluster center. Stars close to the black-hole
"whirlpool" orbit at a faster rate, in keeping with fundamental laws
of orbital motion around a massive central body, as described by
Johannes Kepler four centuries ago.

Black holes cannot be seen directly. Some emit X-rays, or show other
telltale evidence of their presence, when they capture nearby
material. However, the dark objects in the centers of G1 and M15
are quiet. Nonetheless, they are presumed to be black holes because
of their small size and large mass. An alternative explanation
would be to assume that the centers of these clusters harbor a
swarm of neutron stars or other exotic objects that sank to
the cluster's center. However, theoretical studies do not predict
swarms that are massive enough to account for the Hubble observations.

Astronomers have searched for black holes in globular clusters for
nearly 30 years. The roadblock has been the fact that ground-based
telescopes cannot easily resolve the stars closest to the suspected
black hole. As far back as the 1970s, hunting for globular-cluster
black holes was recognized as a task suited for Hubble Space
Telescope's exquisite resolution, which is needed for looking
close to a black hole. The researchers say that the quest is now over.

To further understand these issues, it is now extremely important
to search for black holes in other star clusters as well. Some
globular clusters are so close to us that, if they had black holes,
we would be able to probe closer to these monsters than we have
ever been able to before.

Maybe I was wrong about globular clusters. Looks like the HST was the key
as globular black holes are 'quiet'.

Oh well. Live and learn. I've still not heard of any black holes found in
open clusters (very small globulars) or irregulars.

Rich

Joseph Lazio replied:
"R" == Rich writes:


R Brian Dickens replied:

sooncf wrote:

But there is a giant black hole in the centre of each galaxy.


There's a giant black hole in our galaxy, yes - but I've never
heard of your claim of a black hole being at the centre of *every*
galaxy...


R It may be true for some types of galaxies (...), but it's clearly
R not true for irregulars or globular clusters.

It seems that there is a massive black hole in the center of most
(all?) large galaxies, spiral or elliptical. Why? It's not clear,
but the formation of central black holes and of galaxies may be tied
together.

Globular clusters clearly contain neutron stars. They almost
certainly contain black holes in or near their centers, unless star
formation during the formation of globular clusters were biased
*against* massive stars (which seems difficult to understand).

Globular clusters tend to have a greate collision rate than spirals,
probably due to their orbits, which are speherical about the center of
gravity rather than aligned about a common axis. They also seem to have
very uniform populations of type II stars, generally of pretty much
the same mass. As a result, some of the collissions will form more
massive stars, known as "blue stragglers". There is an upper limit of
mass to stars in globular clusters and blue stragglers are not only
above the limit, but younger and hotter than the other stars in the
cluster.

http://www.haydenplanetarium.org/hp/...5stelcoll.html
http://www.solstation.com/x-objects/bluestrag.htm

I'd suspect that the same mechanims, or encounters that result in a
close binary could eventually lead to some of these stars acquring
enough mass to form a neutron star. Interestingly, I can't find any
material dealing with this directly, although there is lots which
simply refers to the grater incidence of neutron stars in globular
clusters.

http://www.universetoday.com/am/publ..._binaries.html

This was interesting.

http://universe.gsfc.nasa.gov/press/...sar_skytel.pdf

Hmmm, found this...

http://www-int.stsci.edu/~marel/m15release.html

[...]

Marel led a team that uncovered a black hole in the center of the
globular star cluster M15, 32,000 light-years away in the
constellation Pegasus. His collaborator Joris Gerssen, also of
the Space Telescope Science Institute, pinned down the black hole's
mass at 4,000 times that of our Sun.

In a separate observing program, a team led by Rich, and including
Gebhardt and Luis Ho of the Carnegie Institution of Washington,
found a 20,000-solar-mass black hole in the giant globular cluster
G1, located 70 times farther - 2.2 million light-years away - in
the neighboring Andromeda galaxy. By contrast, stellar-mass black
holes are only a few times the mass of our Sun, and galactic-center
black holes can be millions or billions of times more massive than
our Sun.

"G1 has a total mass of 10 million suns, making it about the most
massive globular cluster known." says Rich. "It also has a very
bright core, so I thought it would be a good place to search for
a massive black hole."

A black hole is an infinitely small and dense region where space
is so tightly warped by gravity that not even light can escape. For
many years, astronomers have known two types -- "supermassive" black
holes at the centers of large galaxies and the so-called "stellar-mass"
black holes that result when a star about 10 times the Sun's mass ends
its life in a supernova explosion. Both types have been detected and
measured.

"There are two main theories of black hole formation," says Gebhardt.
"You could either make the black hole all at once, when the galaxy
is forming, by dumping a lot of material in the middle, or you could
start with a seed black hole that subsequently grows over time. The
observational evidence now points to the idea that you start out
with a small seed black hole." The fact that globular clusters have
these small black holes implies that they are excellent candidates
to act as the seeds for the supermassive black holes that lurk in
the centers of nearly all galaxies.

"The Hubble results add new credibility to the latter scenario,"
says Van Der Marel. "Black holes similar to the ones now found
in globular clusters may have been the building blocks that formed
supermassive black holes."

Previously, X-ray observations from the ROSAT Observatory and
NASA's Chandra Observatory have identified ultra-bright X-ray
sources that could also be interpreted as intermediate-mass black
holes in star-forming galaxies. However, alternative interpretations
for these X-ray sources continue to exist. By contrast, Hubble's
measurements are based on the velocities of stars whirling around
in the dense cores of globular clusters, which yield a direct
measurement of the black hole masses.

The M15 globular star cluster is close enough that individual star
speeds can be measured. By contrast, the G1 observations rely on
measurements of the collective properties of many stars. In either
case, a black hole can be identified by using a common Hubble
black-hole-hunting technique, which searches for a rise in
velocities toward the cluster center. Stars close to the black-hole
"whirlpool" orbit at a faster rate, in keeping with fundamental laws
of orbital motion around a massive central body, as described by
Johannes Kepler four centuries ago.

Black holes cannot be seen directly. Some emit X-rays, or show other
telltale evidence of their presence, when they capture nearby
material. However, the dark objects in the centers of G1 and M15
are quiet. Nonetheless, they are presumed to be black holes because
of their small size and large mass. An alternative explanation
would be to assume that the centers of these clusters harbor a
swarm of neutron stars or other exotic objects that sank to
the cluster's center. However, theoretical studies do not predict
swarms that are massive enough to account for the Hubble observations.

Astronomers have searched for black holes in globular clusters for
nearly 30 years. The roadblock has been the fact that ground-based
telescopes cannot easily resolve the stars closest to the suspected
black hole. As far back as the 1970s, hunting for globular-cluster
black holes was recognized as a task suited for Hubble Space
Telescope's exquisite resolution, which is needed for looking
close to a black hole. The researchers say that the quest is now over.

To further understand these issues, it is now extremely important
to search for black holes in other star clusters as well. Some
globular clusters are so close to us that, if they had black holes,
we would be able to probe closer to these monsters than we have
ever been able to before.

Maybe I was wrong about globular clusters. Looks like the HST was the key
as globular black holes are 'quiet'.

Oh well. Live and learn. I've still not heard of any black holes found in
open clusters (very small globulars) or irregulars.

Rich

Rich wrote:
It may be true for some types of galaxies (hypothetically, I'm not saying
it is), but it's clearly not true for irregulars or globular clusters.


The case for there being a strong connection betwen galaxy formation
and black holes seems to be growing.
Here's a "popular" report:
http://www.space.com/scienceastronom..._030128-1.html

It's possible that globular clusters might contain lower mass black
holes. There were some reports of the detection of a black hole in
M15. e.g. press release at:
http://www-int.stsci.edu/~marel/m15release.html

However, this claim was later retracted.