Query inre: Mission Of Gravity by Hal Clement

[thebigcat]

NASA's stargazer Q&A page synopsizes the book thusly:<br /><br />"Many years ago Hal Clement (real name, Harold Clement Stubbs) wrote a wonderful work of science fiction titled "Mission of Gravity", about a planet made of very dense and enormously strong material. The planet rotated extremely fast, and its equatorial radius was several times its polar radius. Gravity at the equator was weakened by the centrifugal force and by the greater distance from the center, to where a human could land there. However, regions closer to the pole were habitable only to local creatures, many-legged squat crawlers (highly intelligent, too). Even they had trouble reaching the pole, where the mission of the book takes them." <br /><br />I have some trouble with the basic premise. Clement's fictional super-jovain world Mesklin has an effective surface gravitation ranging between 3 Gs at the poles and nearly 700 Gs at the equator. When a friend told me of this book several years ago I almost immediately told him that Clement was wrong. (You can guess what reaction that comment earned) It seemed obvious to me that no matter how much spin imparted on a planet it would always order it's mass so that the effective gravity at it's surface (Expressed as a balance between lateral acceleration and gravemetric acceleration) was constant.<br /><br />I did some web searching, and according to an article in space.com Clement was informed by students at MIT (probably taught by the same professor who's students were running around the World Sci Fi convention screaming "The Ringworld is unstable" the year after Larry Nivin won the Hugo for writing his classic.) that they had reworked his original slide-rule calculations with their speffy supercomputers and found that his planet would, according to his figures for mass and rotation, have a much more spherical shape. I wasn't able to find anything refuting his posit on the planet's surface gravitation, however.<br /><br />Any help in this matter would be <div class="Discussion_UserSignature"> </div>

 

[jmilsom]

I have read Clement's book and think it is great. It is a work of fiction, and SciFi of course takes great license in bending our accepted laws of Physics.<br /><br />Although it comes from a SciFi book, it may be more useful to pose this real physics question in the Space Science and Astronomy Forum. I'm am sure there are many there who would love to tackle this one! <div class="Discussion_UserSignature"> </div>

 

[thebigcat]

Whoever said "Never let the facts get in the way of a good yarn" undoubtably wasn't talking to science fiction writers specifically, and I'm sure that Clement was certain that his story was on sound physical footing when he wrote it. But remember that a science fiction writer needs to be a writer first and a scientists second when he sits down at his word processor. Like Dr. Asimov, Clement, despite the day gig, fulfilled this admirably. <b>A Mission Of Gravity</b> is a good yarn. Okay, the title is a horrid pun, but I suspect that the original title was rejected in favor of one supplied by Fred Pohl on John W Campbell's directive.<br /><br />I would guess that the story began as an excercise, much as Campbell told young Asimov to "Imagine a world where the sun never sets. Now, what if it did?" The result of that conversation was <b>Nightfall</b>. So Clement set out to write a story set on a planet where the gravity was not uniform across the surface and constructed a world that he thought would fill the bill. My guess is that he was wrong in that, but I don't have the math to prove it, which is why I am asking for help from the members here.<br /><br />And all aspiring science fiction writers remember : Bad science in a sci-fi novel is forgivable. It can easily be overlooked if the story is sound. But poor writing in even the most scientifically sound tale is the kiss of death. Campbell made certain that his young writers understood that fact long ago, and his legacy is an entire generation and beyond of great writers, even to our modern "post-literate" society. <div class="Discussion_UserSignature"> </div>