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>From OTA@S1-A Fri Feb 26 01:31:22 1982

SPACE Digest                                      Volume 2 : Issue 116

Today's Topics:
				 Quasars
			    Wierd accelerators
		       flying short, stubby I-beams
				 Quasars
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Date: 25 Feb 1982 0716-PST
From: Paul Dietz <DIETZ at USC-ECL>
Subject: Quasars
To: Reed.ES at PARC-MAXC
cc: space at MIT-MC

Gravitational redshift is ruled out because the redshift is so great.
A large cluster of stars (say) of sufficient density to get that redshfit
would be unstable to gravitational collapse.

If the quasars are local objects associated with our galaxy, calculations
indicate that the energy necessary to accelerate them to their observed
velocities is many, MANY solar masses, far too much to be believable.
And why don't we see them around other galaxies, blue-shifted?

Some evidence for the traditional view includes the fact that quasars
resemble less active radio galaxies in that they have radio lobes,
and the observation of a gravitational lens involving a quasar.  This
last doesn't work unless the quasar is very far away.
-------

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Date: 25 Feb 1982 09:40 PST
From: Stewart at PARC-MAXC
Subject: Wierd accelerators
To: Space@MIT-MC
cc: Stewart

Take the skyhook rope, tie a probe on the end, and whirl the affair around a
suitable asteroid.  As the rope wraps around the asteroid, the probe will reach 0.5
c and then you let go.

At least as feasible as the bloater drive.

	-Larry

PS  Remind me to write up my wood burning TV receiver.

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Date: Thursday, 25 February 1982  09:41-PST
From: KING at KESTREL
Subject: flying short, stubby I-beams
To: ota at s1-a
cc: King at KESTREL, space at mit-mc

	I seem to remember that the strength required of an object  of
a given design to resist a  given acceleration is proportional to  the
cube root of its mass.  (All load-bearing members' cross sections  are
proportional to the square of a linear dimension, and the the mass  of
the object is proportional to the cube.)
	If I remember correctly, the  strength of structural steel  is
approximately 1000 KPSI.   If I wanted  to send an  I-beam to  another
galaxy, the load on  its base would have  to be < 1  PSI, so it  could
only be 6  inches tall.  My  recollection of steel's  strength may  be
wrong, but  not  drastically.  There  are  stronger materials,  but  a
factor-of-100  improvement  is  clearly   necessary  (it  would   seem
necessary for the ship to be at least 50 feet front-to-back).  I would
also assume that the intention  is to send something more  interesting
than an I-beam.
	Intellegent  artillery  shells  are   made  out  of   stronger
materials then  structural  steel.   They  also  are  virtually  solid
inside.  They  are  less then  6  feet  long, and  they  are  tapered.
Probably our artillery pieces deliver 100,000G because more then  that
was deforming even dumb, passive shells.

						Dick

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Date: 25 Feb 1982 11:15 PST
From: Wedekind.ES at PARC-MAXC
Subject: Quasars
To: Reed.ES at PARC-MAXC
cc: Space-Enthusiasts at MIT-MC, Wedekind.es

Larry,

	If you say that all of the quasar redshifts are due to velocities which are
unrelated to the recession of the galaxies then it's hard to explain why none of
them are blueshifted - that is, approaching us.

	Also, I think I read that people have reason to believe these redshifts
aren't due to gravity. Does anyone know more about this?

						Jerry 

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End of SPACE Digest
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