🚀 go-pugleaf

>From OTA@S1-A Sun Feb 28 03:46:17 1982

SPACE Digest                                      Volume 2 : Issue 117

Today's Topics:
				 quasars
			       Shuttle News
			  Quasars as spaceships
			       re: quasars
			      quasar beliefs
			     quasar redshifts
----------------------------------------------------------------------

From: CARLF@MIT-AI
Date: 02/27/82 15:54:34
Subject: quasars

CARLF@MIT-AI 02/27/82 15:54:34 Re: quasars
To: space-enthusiasts at MIT-MC
	In the most recent (or perhaps last week's) issue of Nature
there are two articles on Arp's theory of the nearness of quasars,
both unfavorable. 
	The first article considers Arp's assertion that a survey of
the sky in the vicinity of nearby galaxies shows a higher than
average density of quasars, and thus that the quasars must be
associated with the nearby galaxies. Arp claims that the data have
one chance in 10^17 of happening by chance, but the article
disagrees with this. It states that the probability of the data
occuring by chance are about 1/2. The article's description of Arp's
method of analysis makes it seem dubious even to me, though I know
little of statistical analysis.
	The second article is of a statistical nature, and examines
Arp's claim that several sets of three quasars lie almost on
straight lines, and yet have very different redshifts, showing that
redshifts must not correlate with distance. The article disputes
Arp's claim that these alignments are immensely improbable. It
argues that Arp has incorrectly analyzed his data.  The suggestion
that quasars might be interstellar spaceships going away from us
makes me wonder why we don't see any coming toward us. Are we so
frightening that everyone is running away, or is something ghastly
going to happen to this part of the galaxy that we haven't noticed
yet?


					-- Carl

------------------------------

Date: Sat Feb 27 08:22:09 1982
To: Space at MIT-MC
From: ucbvax!ihnss!cbosg!harpo!npois!rabbit!sjb at Berkeley
Subject: Shuttle News
Source-Info:  From (or Sender) name not authenticated.


The unloading of supercold hydrogen and oxygen fuels went well,
just as their loading did, leading the way for the last major
step before the shuttle's countdown begins.  Also tested out
well were the three fuel cells and APU #1.  The fuel cell that
caused the problems during STS-2 had been replaced and all
three overhauled to prevent a recurrence of that problem.
If all goes on schedule now, loading of highly volatile
fuels into the Columbia's maneuvering system will start
next week.  It was this loading of nitrogen tetroxide and
liquid hydrazine that spilled during the pre-flight work
of STS-2 and subsequently delayed its launch while workers
fixed the tiles that were loosened during that accident.
As of now, the work for STS-3 is still a bit ahead of
schedule, giving a nice cussion if anything should go wrong.

------------------------------

Date: 27 Feb 1982 1722-PST
From: Hans Moravec <HPM at S1-A>
Subject: Quasars as spaceships
To:   space at MIT-MC  

One of the features of efficient rockets is a tightly collimated
exhaust.  A rocket that converted a high mass fraction of its
fuel to energy (near photon drive) would emit mostly photons
frequency shifted by the motion of both the photon source and the
acceleration of the exhaust reflector/nozzle, and these photons
would be like a searchlight beam streaming from the rear of the
ship.  This beam would be so bright compared to any other emission
that it is probably safe to say that we could see the ship only when
the exhaust is pointed straight at us.  We would see a blue shift
only if a ship was using its engines to decelerate along our line of
sight. There may be better ways of decelerating than using mass quantities
of fuel, things like an interstellar hydrogen parachute, or interaction
with the galactic magnetic field, and these would render the ship
invisible to our feeble sensors in the only blue shift case.
Another, maybe significant, effect is relativistic beam angle aberration.
A source with a given beam angle seems to have a narrower beam
when it is coming at you and a wider angle when moving away.  Thus
we have a greater chance of seeing a red shifted receding beam source
than a blue shifted approaching one.

------------------------------

Date: 28 Feb 1982 00:24:14-PST
From: decvax!utzoo!utcsrgv!dudek at Berkeley
To: utzoo!decvax!ucbvax!space@Berkeley
Subject: re: quasars
Cc: decvax!utzoo!utcsrgv!ings@Berkeley

  Is this where to send space disgest stuff?
  There was an article in the Canadian Journal of Physics about 2 years
ago (I'll try & find it) postulating that quasars could be accounted for
as a statistical anomaly in the way spectral data was identified.  
Essentially, I think the thesis was that the "supposed" red shifts were 
identified by matching observed spectral lines with known arrangements
and then finding out how much the familiar configuration was shifted up the
spectral scale.  The author claimed that a number of spurious random
matches could account for "quasars", and in fact the number of known quasars
jived with this explanation.
			Gregory Dudek
			UNIX. of Toronto
			..decvax!utzoo!utcsrgv!dudek

------------------------------

Date: Fri Feb 26 16:14:44 1982
To: Space at MIT-MC
From: ucbvax!decvax!utzoo!henry at Berkeley
Subject: quasar beliefs
Source-Info:  From (or Sender) name not authenticated.


I know nothing about the facts of the particular case of the astronomer
who may lose his observing time because of unconventional beliefs about
quasars.  But it is worth remembering that just because somebody holds
unconventional beliefs about some sacred cow does NOT mean that his
research is well-organized, properly thought out, and deserving of
observing time.  If his observing time is imperiled BECAUSE of his views,
that is deplorable.  But don't forget that there may be a simpler and
less dramatic explanation.

I confess to a strong suspicion myself that the standard "cosmological"
explanation of quasars is incorrect, but that does not blind me to the
possibility that people who agree with me may not be organizing their
work well enough to deserve time on scarce and expensive facilities.

------------------------------

Date: Fri Feb 26 16:44:01 1982
To: Space at MIT-MC
From: ucbvax!decvax!utzoo!henry at Berkeley
Subject: quasar redshifts
Source-Info:  From (or Sender) name not authenticated.


The two possible explanations of the quasars given a few days ago
missed a third:  that the red shifts really are Doppler effect, but
this does not correlate with distance the way it does for galaxies.
In other words, you can eliminate the need for a non-Doppler redshift
mechanism if you can devise a way of accelerating starlike objects
to substantial fractions of c (interactions with the magnetic field
of an exploding galactic core?).  At one time this was a respectable
theory;  I don't know its current status.  One problem is that one
should then see some blueshifted objects as well, although one can
fend this off by claiming that we aren't looking at the right
wavelengths to see the major emissions of a massively blueshifted
object.  How this explanation stands in the presence of increasing
astronomy efforts in the UV and X-rays, I don't know.

Any attempt to avoid the "cosmological" explanation of quasars also
needs to bear in mind that things like the recent case of double
images of a quasar being formed by gravitational lens effects of
a distant galaxy DO put a lower bound on the distance of SOME quasars.

------------------------------

End of SPACE Digest
*******************