archive: SETI LETTERS TO THE MODERATOR, 12 May 1999

SETI LETTERS TO THE MODERATOR, 12 May 1999

Larry Klaes ( lklaes@bbn.com )
Wed, 12 May 1999 11:32:06 -0400

>From: Benny J Peiser <b.j.peiser@livjm.ac.uk>
>Sender: humbpeis@livjm.ac.uk
>To: CCNet-Letters@livjm.ac.uk
>Subject: LETTERS TO THE MODERATOR, 12 May 1999
>Date: Wed, 12 May 1999 09:15:53 -0400 (EDT)
>Priority: NORMAL
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>
>LETTERS TO THE MODERATOR, 12 May 1999
>-------------------------------------
>
>(1) ARE LOCAL ETs SHORT-SIGHTED?
> Alan Fitzsimmons <A.Fitzsimmons@Queens-Belfast.AC.UK>
>
>(2) RESPONSE TO ALAN FITZSIMMONS
> Gregory Matloff <gm21@is3.nyu.edu>
>
>(3) THE CAPTURE THEORY OF THE ORIGIN OF THE SOLAR SYSTEM
> John McCue <mccue@johnast.demon.co.uk>
>
>(4) AND FINALLY....
> Robert Matthews <rajm@compuserve.com>
>
>
>=============
>(1) ARE LOCAL ETs SHORT-SIGHTED?
>
>>From Alan Fitzsimmons <A.Fitzsimmons@Queens-Belfast.AC.UK>
>
>Dear Benny,
>
>Just a comment on Gregory Lee Matloff's suggestion of looking at KBOs
>for sign of ET presence. I am a big fan of SETI, and believe that
>looking at alternatives to 21-cm searches is a good thing. So
>considering different methods of SETI, what Gregory has done, should
>be applauded. However, having looked at the web site mentioned, I find
>the reasoning behind this particular strategy to be unconvincing.
>
>The statement is made that the colour of some KBOs are very red, and
>that the reason for that is unknown. In fact, it is entirely
>unsurprising. Many small bodies in the outer Solar system share this
>property, from the Trojans at 5.2 AU outwards. It is generally
>believed to be due to the irradiation of organic-bearing ices on the
>surfaces of these bodies.
>
>What was surprising was finding in the paper quoted on the web site
>(Tegler and Romanishin 1998) that there may exist two distinct
>spectral classes in the Kuiper belt. This point is still debated, and
>it is fair to say that no consensus has yet emerged between the
>people working in this area. That there is a wide variation in
>optical and near-IR colour is undisputed, but work by Jane Luu and
>others implicates the past collisional and resurfacing histories of
>these bodies as the cause, rather than any artificial culprit.
>
>Finally, the existence of the belt itself is well explained by
>current formation theories (hence its name!), and there is no reason
>to suspect it is full of ET spacecraft.
>
>In summary, there is no observational reason to look at the Kuiper
>belt for ETs rather than the asteroid belt, or I guess any other
>place in the Solar system that can handle stable orbits. I will let
>someone else comment on the prospect of finding ETs on NEOs, although
>placing yourself on a body that will one day hit a planet or the Sun
>is a bit short-sighted in my opinion!
>
>Best Wishes
>Alan
>
>============
>(2) RESPONSE TO ALAN FITZSIMMONS
>
>>From Gregory Matloff <gm21@is3.nyu.edu>
>
>Thanks for the opportunity to respond to Dr. Fitzsimmon's comments
>regarding the possibility of ET habitats among the Kuiper Belt.
>First, the anomolous red excess of some Kuiper objects had been
>discovered but not explained while the NIDS essay was under
>preparation. One paper a few months ago in Icarus, I believe,
>explains this red-excess as caused by Tholin, a natural organic
>compound.
> We need a true infrared excess to really point towards the
>possibility of an ET habitat.
> I think that the Kuiper or Oort Belt objects are better habitat
>sites than most main-belt asteroids because of the larger
>concentration of water-ice in these objects. Of course, some
>main-belt objects are almost certainly hydrated as well.
> The main argument of my essay, and one that is very hard to
>argue with, is that the solar-system may have been colonized. As I
>will present in a co-authored paper during the Amsterdam IAF Congress
>in October 1999, this is probable if one in 10,000 stars or so has
>evolved a long-lived technological civilization. This is the basic
>unknown--how many ET techies are there???---GREG MATLOFF
>
>================
>(3) THE CAPTURE THEORY OF THE ORIGIN OF THE SOLAR SYSTEM
>
>>From John McCue <mccue@johnast.demon.co.uk>
>
>Dear Benny,
>
>May I make this contribution, my first?
>
>The latest BBC TV production "The Planets" prompted me to contact my
>former supervisor, Dr. John Dormand at Teesside University, UK, for
>his views. The first programme in the BBC series discussed the
>formation of the planets exclusively, and at length, in terms of the
>accretion theory, though it admitted that the formation of Uranus and
>Neptune by accretion cannot yet be established by computer modelling.
>John Dormand is well aware of this, being a collaborator on the
>alternative Capture Theory with Prof. Michael Woolfson, of York
>University, also in the UK.
>
>The Capture Theory proposes that the planets formed in the same way
>as stars, i.e. by the gravitational collapse of material. In
>particular, this cool material is captured by the sun from a
>protostar.. John has given me permission to reproduce extracts from
>his joint book on the subject "The Origin of the Solar System" (Ellis
>Horwood, UK, 1989), as follows.
>
>"The early capture theories of Schmidt (1947), and Lyttleton (1961)
>rely on random processes occurring in a dispersed medium for the
>actual production of planets. A satisfactory description of such
>processes is still to be found despite the close attentions of many
>nebula cosmogonists (e.g. Safronov, 1972). The only undisputed
>mechanism permitting the condensation of tenuous material to form
>relatively dense bodies is gravitational instability, and all
>theories of star formation rely on this process. It seems reasonable
>to suppose that planets are formed in a similar way. Of course, a
>cloud of planetary mass will not condense if it is too hot. It is
>logical to propose two major requirements of a theory of the origin
>of planetary systems:
>
>1. planetary material must be captured (to solve the angular momentum
> problem);
>2. primitive planetary material must be sufficiently cool and dense
> to be gravitationally unstable.
>
>The Capture Theory, proposed originally by Woolfson, satisfies both
>of these requirements. In this theory, it is proposed that an
>encounter took place between the sun and a cool protostar, both
>bodies having originated in the same stellar cluster. The density of
>stars in a young cluster would be sufficiently large to make close
>encounters fairly common. During a close approach, the protostar
>would be greatly affected by solar tidal forces. Material would be
>removed from the protostar, captured by the sun, and eventually form
>the planetary bodies by gravitational collapse. The Capture Theory
>proposes that the protostar is a very extended body, and therefore
>not well-described by a single point mass. Fortunately, the power of
>computer modelling is able to test this theory in a comprehensive
>manner. The results indicate the plausibility of the Capture Theory
>for the formation of the planets beyond any reasonable doubt."
>
>The discoveries in recent years of protoplanetary disks does not
>necessarily lend weight against the Capture Theory. In a recent
>correspondence with me, John Dormand wrote "I can't see why a capture
>mechanism is at odds with 'protoplanetary disks'. Perhaps these are
>also the products of tidal events."
>
>After ten years of modesty, perhaps the time is right for the Capture
>Theory to be considered by the wider astronomical community, and
>accepted as a work that can explain the observed features of the solar
>system.
>
>Dr. John McCue, FRAS,
>40, Bradbury Rd.,
>Norton,
>Stockton-on-Tees,
>UK,
>TS20 1LE
>
>============
>(4) AND FINALLY....
>
>>From Robert Matthews <rajm@compuserve.com>
>
>Hi Benny
>
>> >(9) STILL NO CLUES AS TO WHY AGRICULTURE WAS INITIATED
>> >
>> >A.M. Mannion: Domestication and the origins of agriculture: an
>> >appraisal. PROGRESS IN PHYSICAL GEOGRAPHY, 1999, Vol.23, No.1,
>> >pp.37-56
>
>Shouldn't the reference read: LACK OF PROGRESS IN PHYSICAL GEOGRAPHY ?
>
>best wishes
>Robert
>
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