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A very, very belated realization about A World Out of Time
james_nicoll
Peerssa, the rather nasty bureaucrat who manages Corbell during his training, has a copy of his mind beamed out to Corbell's hijacked starship in an attempt to salvage the terraforming mission. The thing is



the brain scanning process is explicitly said to be destructive: once it's done, you're left with a brain smoothy. For there to be a ship-Peerssa, the meat-Peerssa has to have died. I don't meat-Peerssa's death is even actually mentioned during the book but it's implied by the technology.

Do you think Peersa volunteered or was this his punishment for losing a starship?

Smoke Ring

(Anonymous)

2009-11-17 09:30 pm (UTC)

The problem there was, I didn't really believe in that setting the way I believed in the Ringworld. For starters, I didn't think that Niven had done the math.


Doug M.






Even if there is no way to make the setting work, Schroeder's Virga idea helped suspend my disbelief regarding that sort of setting.

I do keep wondering if there is some way to get Niven's Smoke Ring to occur. Much of the criticism on Usenet pertained to the expected chemistry of an atmosphere of a Neptune-like world, but since then, there's been new speculation about super-earths with very deep oceans and other novel planetary environments.

I also am unclear on what happens if you put our Earth, with its present-day atmosphere and life where Gold is, but tweak the mass of the neutron star, so that the gravity gradient is sharper -- can you get a gas torus with a habitable atmospheric pressure?

I'm sure you're busy, and I'm not asking you in particular for an answer, but I thought I would throw these comments out there.

I also am unclear on what happens if you put our Earth, with its present-day atmosphere and life where Gold is, but tweak the mass of the neutron star, so that the gravity gradient is sharper -- can you get a gas torus with a habitable atmospheric pressure?

I think if you check rec.arts.sf.science, the setting is discussed and show to be fatally flawed in any number of ways and the unworkability of the torus is one of them.

I looked for just this sort of analysis and didn't find it (the math is beyond me, but I trust Eric Max Francis et al). I'll look again!

If you do, please link...

Erik Max Francis on the Smoke Ring

(Anonymous)

2009-11-18 01:28 am (UTC)

The discussion I remember is one featuring the following post:

Newsgroups: rec.arts.sf.science
From: Erik Max Francis <m...@alcyone.com>
Date: 1996/03/10
Subject: Re: Smoke Ring

I think the case that there's a basic math error (deliberately or not) is pretty strong.

Hi Bill!

I will.

The anonymous post above this one seems to be referring to this Usenet thread:

http://groups.google.com/group/rec.arts.sf.science/browse_frm/thread/c88b2a2b6066525/112391e10ab7b8ca?tvc=1#112391e10ab7b8ca

The thread alternates amusingly between discussing The Smoke Ring and Neutron Star, but when you filter out the discussion of Neutron Star, you can see Eric Max Francis discussing a math error by Niven. If I understand correctly, the only implications for the math error are that the description of the integral trees themselves may be inaccurate, because the tidal effects would be weaker than those described by Niven -- the math error is not significant enough to debunk the smoke ring itself.

Eric Max Francis also questions whether ~100 kPa of pressure could be maintained in the densest part of the smoke ring, but the answer seems to be that the gas giant outgasses rapidly, and that the gas must be replenished from the torus equally rapidly. Also, David Wayne McKee's comment (#45) isn't refuted.

Much of the discussion seems centered on the unlikely ratio of H and He to oxygen and water, given that a gas giant is the source of the atmosphere. Answers are proposed in the thread, and I was thinking the newest models of super-earths might be helpful in providing additional answers. I think there are likely to be more kinds of planetary atmospheres than were dreamed of in Eric Max Francis' philosophy...

I'm still not sure on whether the Earth itself could provide enough atmosphere for a smaller and narrower habitable smoke ring around a different neutron star, although I expect the answer to be that the Earth doesn't have enough atmosphere for that.

I can't believe I posted to that thread thirteen years ago.

Okay, my thanks to you and to Anonymous.