Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V15_0/V15NO041.TXT

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Date: Mon, 27 Jul 92 05:01:19
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #041
To: Space Digest Readers
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Space Digest                Mon, 27 Jul 92       Volume 15 : Issue 041

Today's Topics:
                Antimatter (was propulsion questions)
                    Methods for meteor avoidance
                        Whales (SETI) (2 msgs)

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Date: Sun, 26 Jul 1992 23:26:23 GMT
From: James Davis Nicoll <[e-mail]>
Subject: Antimatter (was propulsion questions)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] writes:
>[e-mail] (James Davis Nicoll) writes:
>>    Given that one can mix the antimatter-reaction mass ratio to get
>>the Vexhaust one wants, the dangers of standing in the vicinity of the
>>exhaust of an antimatter powered ship could be *identical* to that of
>>standing inthe vicinity of a conventional ship.

>Actually there is one piece of information missing here. In a conventional
>rocket most of the exhaust is being used to push more fuel closer to orbit.
>In an antimatter rocket, you have a much higher payload/fuel ratio, so for
>the same payload, there will be much less exhaust.

    Odds are the antimatter will be the expensive component of the
reaction-mass/'fuel' mix, and so the am-reaction-mass ratio will be such
that the am is used as efficiently as possible. The mass ratio is smallest
if there is a 50% am, 50% matter mix, but that uses much more am then
a mixture of am/m which is mostly matter. I would bet the population of
Gary, Indiana that if antimatter energised propulsion systems are used
from Earth's surface to reach orbit, the exhaust velocity  will be in the
10 km/s range, rather than close to C.

    Also, 'pure' photon drives tend to produce oodles of nasty
hard radiation which could very well fall outside the allowable ranges
of todday's litigation prone society, plus they suck up power like a
mad fiend.

                            James Nicoll

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Date: Mon, 27 Jul 1992 00:37:24 +0000
From: Andrew Haveland-Robinson <[e-mail]>
Subject: Methods for meteor avoidance
Newsgroups: sci.space

In article <[e-mail]> [e-mail] writes:

>After the meteor from last year passed withinn 4 minutes of the earth (the
>large one), I was wondering if we have any system of avoiding these
>large beasts??!! I read that if it hit the earth, millions could have died.
>
>With a problem like this, surely there must be some defence!!!
>

One idea springs to mind if you know the time and direction of impact, get
to the other side of the Earth PDQ!  Or live in a polar climate, the chances
of getting a direct hit should be a bit less, although similarly
catastrophic to a perpendicular strike.

I don't try to lie awake worrying about it though...

Andy.

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

Date: Sun, 26 Jul 1992 23:25:20 GMT
From: russell wallace <[e-mail]>
Subject: Whales (SETI)
Newsgroups: sci.space

In <[e-mail]> [e-mail] (John Roberts) writes:


>-From: [e-mail] (russell wallace)
>-Subject: Re: Whales (SETI)
>-Date: 23 Jul 92 21:10:39 GMT
>-Organization: Trinity College, Dublin

>-Whales are _not_ intelligent in any significant sense of the word. If
>-they were, they could prove it in about 30 seconds, by any number of
>-means (e.g. whistle the prime numbers, *-* *-*-* *-*-*-*-* etc. - for
>-that matter just whistle the numbers from 1 to 10). In fact, if they
>-were intelligent, since they were physically quite a lot tougher than
>-the whaling ships of the 18th and 19th centuries, they could have
>-developed tactics to defeat them (e.g. several whales surround a whaling
>-ship and clobber it, rather than all the whales trying to dive, and the
>-ship gets one of them).

>Again, one shouldn't expect all whales to have the same level of intelligence.
>It has been reported that there was once a group of killer whales that
>cooperated with a family of Australian whalers over the course of several
>generations. They would help to round up the big whales to be killed, then
>eat the leftovers. Rival whalers encroaching in the territory were driven off
>by the killer whales.

A better explanation might be that the whalers trained the killer whales
to do this, in the same way that humans can train dogs to help them hunt
on land. Killer whales can certainly be trained to do the sort of things
that dogs can be trained to do.

>Whales clearly lack some of the intellectual capabilities of humans (for
>instance, humans don't appear to be prone to mass beachings). It would be
>interesting to find out what capabilities they do have, for instance in the
>area of abstract reasoning.

It certainly would. As I said, I think that so far there is no evidence
that they have any reasoning abilities at all.

















--
"To summarize the summary of the summary: people are a problem"

Russell Wallace, Trinity College, Dublin
[e-mail]

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

Date: Sun, 26 Jul 1992 23:19:22 GMT
From: russell wallace <[e-mail]>
Subject: Whales (SETI)
Newsgroups: sci.space

In <[e-mail]> [e-mail] (Nick Janow) writes:

>[e-mail] (russell wallace) writes:

>> Whales are _not_ intelligent in any significant sense of the word. If they
>> were, they could prove it in about 30 seconds, by any number of means (e.g.
>> whistle the prime numbers, *-* *-*-* *-*-*-*-* etc. - for that matter just
>> whistle the numbers from 1 to 10). In fact, if they were intelligent, since
>> they were physically quite a lot tougher than the whaling ships of the 18th
>> and 19th centuries, they could have developed tactics to defeat them (e.g.
>> several whales surround a whaling ship and clobber it, rather than all the
>> whales trying to dive, and the ship gets one of them).

>That doesn't prove that they are not intelligent.  They could have reasons for
>letting men kill them; reasons that they understand but we don't.  Look at all
>the absurd things humans do in the name of religion.  Aliens judging humans by
>a few religious fanatics might decide that humans aren't intelligent.  :)

By that argument, you could suggest that chairs are intelligent, but for
reasons we do not understand choose not to reveal that intelligence, and
instead let humans sit on them and push them around. I would suggest
that there is absolutely no reason to believe whales are intelligent,
and that furthermore they definitely do not do certain things that can
reasonably be regarded as showing intelligence, such as using it to
preserve their lives (when humans evolved intelligence, this was the
*first* thing we use it for), and that therefore it is reasonable to
conclude that whales are not intelligent, unless and until we find some
evidence that they are.

(You make suggestions about aliens judging humans by a few religious
fanatics. It isn't just a few whales that have been killed by whaling
ships, it's thousands of whales, of many different species, in areas
separated by thousands of miles.)








--
"To summarize the summary of the summary: people are a problem"
Russell Wallace, Trinity College, Dublin
[e-mail]

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End of Space Digest Volume 15 : Issue 041
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