WHY WOULD WE EXPECT TO FINDQUASARS THAT ARE BOTH BLUE SHIFTED AND RED
SHIFTED IF THEY WERE EJECTED FROM NEARBY GALAXIES?

Hi hmcdoc!

I think you are referring to one of the explanation attempts for the
"local Hypothesis". This hypothesis states that quasars are not the
exotic and extremely far away objects most astronomers think they are,
but rather occurrences in our "local" cosmic neighborhood.

I'm going to start from the beginning, explaining the source of this
theory, which you might actually already know.

Quasars (Quasi-stellar-objects) have been observed by astronomers for
a long while already. From the beginning spectrum analyses of their
light puzzled many a researcher until it was discovered that there
actually were hydrogen absorption lines in the spectrum... only those
lines were shifted far towards the red.

The most obvious explanation for the occurrence of an effect like this
is that the object itself moves away from the observer at great speed.
It is called Doppler Effect and you can also observe it for example
with sound waves when a car is driving towards you and away from you.
The same effect takes place with the light you observe when you and
the source of the light move away from each other, resulting in a red
shift. The same effect would also happen when you and the source of
the light move towards each other - only then the shift would occur
towards the other side of the spectrum: blue.

Taking this Doppler Effect explanation into account, scientists
calculated the speed of the expansion and used this to estimate the
distance according to Hubble's Law (about the expansion of the galaxy
- assuming the galaxy is expanding, which in turn is contested by
few). The distances resulting from those calculations were just too
much to be believable for some scientists, as they would require
extreme amounts of energy for the quasars to be visible over such a
distance.

That is the reason why those scientists create the "local hypothesis"
saying that the red shift is caused by some other phenomenon and the
objects emitting the light are actually much closer than proclaimed by
the theory above.

One of the theories used to explain the red shifts was that of Quasars
actually being "ejecta from the nuclei of galaxies". The red shift
could be explained this way, as the resulting Doppler Effect of the
ejected matter would actually cause a red shift if the ejection vector
points away from the observer. However, that is exactly where the flaw
of this theory is. There is no reason for all ejection vectors to
point away from us. Some (about half, statistically) should actually
point towards us, causing the opposite shift towards blue.

So far nobody ever observed a blue shifted Quasar though.

I think the key to your question lies with the following points:

- The Doppler Effect: If the distance between you and the light source
decreases quickly, the light is shifted towards the blue (request a
clarification on this if you need further explanation how this works
exactly) and if the distance increases it is shifted towards the red.

- The probability of an ejection from a galaxy occurring in a certain
direction: There are many different classes of galaxies, displaying
different geometrical forms. Although it is believed by most
astronomers that the whole universe expands from a central point
outwards, there are still galaxies even in our "cosmic neighborhood"
that don't follow the same movement vectors. This is enough variation
that there should be some ejections towards us as opposed to away from
us, even if there's a factor that makes galaxies always eject things
in a certain direction relative to themselves.
Another point might be that ejections always occur away from the
starting point of the universe. This also doesn't work. There are
galaxies closer to the projected center of expansion and there are
galaxies further away. Would both groups send their ejected matter
away from the center, or even towards the center, then we would see
one group's ejection red-shifted and the other group's blue-shifted.
Again: if you need a clarification on this, please request one!

I hope this helps explaining the question. I will add a few links to
resources which use pictures to explain some of the effects described
as well as more details about Quasars and the "local Hypothesis".

voyager-ga

Additional Resources:

The Universe of Galaxies
http://www.physics.sfasu.edu/markworth/notes/Galaxiesnotes.htm

Flash Animation to explain the Doppler Effect
http://www.explorescience.com/activities/Activity_page.cfm?ActivityID=45

Doppler Effect (geared more towards light and astronomy)
http://archive.ncsa.uiuc.edu/Cyberia/Bima/doppler.html

Expanding Universe and Hubble's Law
http://archive.ncsa.uiuc.edu/Cyberia/Cosmos/ExpandUni.html

FAQ about Quasars
http://www.phys.vt.edu/~jhs/faq/quasars.html

Search Strategy:

"doppler effect"
://www.google.com/search?sourceid=navclient&q=%22doppler+effect%22

"local hypothesis" quasars
://www.google.com/search?sourceid=navclient&q=%22local+hypothesis%22+quasars

I don't think anyone is saying quasars have come from nearby galaxies.
 They're incredibly far away, by all measurements so far.  Those
measurements include Hubble's law, which says the _universe_ (not the
galaxy) is expanding.  The redshifts are believed by many to be
cosmological rather than Doppler. Cosmological redshift occurs when
the universe's expansion increases the wavelength of light.  This, and
the Hubble law, will only happen over incredibly large distances.  The
galaxies near us are influenced much more strongly by the ordinary
pull of gravity. Andromeda is headed for us, not away from us.

The quasars are so highly redshifted that they could be ejected in any
direction (if that's what's happening) and it probably wouldn't be
fast enough to make the overall effect a blueshift.

Finally, while the whole universe expanded from a point, that doesn't
mean anything about galaxies in our neighborhood & their movements. 
The ones close to us aren't going to seem to recede via Hubble's law. 
Additionally, the point was the creation of spacetime, so we can't
look in some direction and say "That's where it all started".

Hi thenextguy,

I'm assuming your comments are in relation to my answer above, so I
will try to address your comments accordingly.

> I don't think anyone is saying quasars have come from nearby
galaxies.

That is what the question is about, thenextguy. Just follow some of
the links listed if you search for "local hypothesis" (and quasars) in
google. The "local hypothesis" fits perfectly with the question
because one of the theories used to explain it is refuted by the
requirement of blueshifted quasars.

> Those measurements include Hubble's law, which says the _universe_
(not the
galaxy) is expanding.

You are correct here - the relevant paragraph should have said:

[quote]
Taking this Doppler Effect explanation into account, scientists
calculated the speed of the expansion and used this to estimate the
distance according to Hubble's Law (about the expansion of the
universe
- assuming the universe is expanding, which in turn is contested by
few). The distances resulting from those calculations were just too
much to be believable for some scientists, as they would require
extreme amounts of energy for the quasars to be visible over such a
distance.
[/quote]

I hope it was obvious from the text that this was a mix-up.

> The redshifts are believed by many to be cosmological rather than
Doppler.

This is true for the Cosmolgical theory most widely used to explain
quasars, however, the question was about the red/blue shift which is
relevant only to the "Local Hypothesis". This hypothesis in turn deals
with distances where the Doppler Effect is more meaningful than
cosmological redshift. In addition to that Hubble used the Doppler
Effect when calculating his constant - the current value of which is
still under debate 80 years later – and that is why I felt it is
appropriate to use it in the explanation of the hypothesis’ creation.

> Cosmological redshift occurs when the universe's expansion increases
the wavelength of light.

As far as I know there hasn't been a definite explanation for the
cosmological redshift. During my research I came across quite a few
documents with different theories - some of them published mere months
ago. But this also wasn’t a point I was focusing on, because it is
only of limited relevancy for the “local theory”.

> The quasars are so highly redshifted that they could be ejected in
any direction (if that's what's happening) and it probably wouldn't be
fast enough to make the overall effect a blueshift.

I'm afraid you missed the point of the question here. One proposed
explanation of the "local hypothesis" says that the redshift occurs,
because, what we perceive to be extremely distant quasars, are in fact
ejecta from local galaxies. You are mixing two different theories if
you add in the redshift we observe, because this "local hypothesis"
theory EXPLAINS the redsift itself by saying it is the observation of
a Doppler redshift caused by the quasars being ejected from local
galaxies (including our own). No relevant cosmological redshift
involved.

> Finally, while the whole universe expanded from a point, that
doesn't mean anything about galaxies in our neighborhood & their
movements.

Correct, but I'm afraid you didn’t under what I was trying to explain.
I will try again:

- There is a basic expansion movement (according to big bang theory)
- there is an unrelated movement of the galaxies (due to various
causes)
- galaxies have different forms
- galaxies have rotational axis unrelated to other galaxies
- some galaxies are stuck closer together, while others are further
apart
- etc.

so even if the ejection vector (according to this "local hypothesis")
would be dependant on any of the factors mentioned above, there would
still be enough variables in any vector equation to account for some
quasars (according to the "local hypothesis") to be blue shifted
instead of all of them just being red shifted (as occurring in
reality). Of course the “expansion vector” has to be looked at
relative to your point of reference, which already excludes it as a
real candidate for such an effect.

> Additionally, the point was the creation of spacetime, so we can't
look in some direction and say "That's where it all started".

As to "That's where it all started" - I presume you are referring to
the "central point" in my text. I tried to simplify and failed,
tripping myself in the process. Some of the explanation for the
probability of a blue shift is wrong as a result, allow me to
reformulate:

There is of course no point in space about which we can say "that's
where it all started". The "central point" is, as you mention, the
creation of spacetime. From there on the expansion movement is more
akin to the stretching of a rubber band in all directions with the
galaxies being needles stuck into it. The average observer sees the
average galaxy move away from his point of view, their relative
“speed” increasing with distance.
For the “local hypothesis”, however, this works at velocities far
smaller than the ejection velocities for red shifted quasars would
have to be (according to the local hypothesis theory), and is offset
in part by other forces like gravitation within the local group.

A last word thenextguy. Quasars are an interesting subject and the
theory I am talking about here isn't very sound IMHO. There would be a
lot of fantastic detail to go into - most of it still very
speculative. However, I have to focus on the question.

The question was about why there should be a blueshift for quasars in
the "local hypothesis" - at least that was how I interpreted the
question. I provided additional information where I felt it would be
necessary, but my focus has to be the question and not what I think is
the correct theory.

I hope I cleared up a few points for you and have to thank you for
pointing out the problems with my explanation.

voyager-ga

That's what I get for trying to do this from memory.  I had overlooked
a few key points that you caught.  That's twice for me - I'm gonna sit
out for a while!

Sorry!