Slashdot Mirror
Nightfall: Can Kalgash Exist?
First time accepted submitter jIyajbe (662197) writes Two researchers from the Indian Institute of Astrophysics investigate the imaginary world of Kalgash, a planetary system based on the novel 'Nightfall' (Asimov & Silverberg, 1991). From the arXiv paper: "The system consists of a planet, a moon and an astonishing six suns. The six stars cause the wider universe to be invisible to the inhabitants of the planet. The author explores the consequences of an eclipse and the resulting darkness which the Kalgash people experience for the first time. Our task is to verify if this system is feasible, from the duration of the eclipse, the 'invisibility' of the universe to the complex orbital dynamics." Their conclusion? "We have explored several aspects of Asimov's novel. We have found that the suns, especially Dovim are bright enough to blot out the stars. Kalgash 2 can eclipse Dovim for a period of 9 hours. We also tested one possible star configuration and after running some simulations, we found that the system is possible for short periods of time."
I would recommend this book to anyone, it's an easy read and thought provoking.
Just because you disagree doesn't mean it's not true.
http://en.wikipedia.org/wiki/Klemperer_rosette
I'd be more surprised if researchers had proved his senary sun system could NOT exist. The man was a visionary.
"A door is what a dog is perpetually on the wrong side of" - Ogden Nash
The words of a true fanatic.
Nevermind the work, the science and the data. It's written in a format I dislike.
*slowclap* well done, sir.
...gis sdrawkcab (usually not responding to ACs; don't bother posting as AC)
Asimov's story only assumes that the suns' and planets' orbits are in that configuration for a few tens or maybe hundreds of thousands of years, not that they are stable for what astronomers would call the long term.
Have you seen all of nature to affirm without any doubt that something doesn't exist?
Besides, just because the overwhelming majority of something is a certain way doesn't mean it can't exist in another way. For instance, while all known beaches organize themselves as flat expanses of sand, there is still a probability that a wave comes along and spontaneously forms a sandcastle, albeit a vanishingly small one. Nobody's ever seen it, and probably nobody ever will, but it's possible. That's just math.
"A door is what a dog is perpetually on the wrong side of" - Ogden Nash
Epsilon Lyrae, and the vast number of amateur astronomers who've known about it for ages, would beg to differ. Two components that are naked-eye visible, one a double, one a triple. All gravitationally bound, and apparently quite dynamically stable. Five other nearby stars may be gravitationally bound to the system as well.
Castor (Alpha Geminorum) is a sextuple system.
But, of course:
"It's simply not possible for a system like this to exist. If you point out that systems like this do exist, it doesn't mean that my statement is wrong, it means that you're a wack job, so just shut up."
Bravo, good AC. Bravo.
Yes. And thank the Heavens for that. I doubt if the authors spent weeks and months on this. This was probably done over a couple of weekends at most. And they probably enjoyed it. It might have even helped them think better about their 'day jobs'. And it shows WHY scientists often get interested in science in the first place. I am an Indian, and I am glad my govt. funded this - even if indirectly. And yes, I know we have a lot of problems that need to be fixed. Just like the rest of the world.
Now, Get the Fuck Off My Lawn.
The rule are multi star systems. Single star systems are the minority.
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
The article actually stated that it was only stable on the short term.
It also seemed pretty obvious to me that the writer wasn't trying to "prove" that star system configuration existed, just that despite it being highly improbably, an approximation of it potentially could exist, at least for a little while. It's kind of like the idea that you could go buy one random lottery ticket and win the jackpot that drawing. It's possible, but it's a lot more likely that you won't, and there's a distinct chance that nobody will win this week, but that doesn't eliminate the possibility.
The problem is not the six suns but the constraints on the planet and moon:
* that the planet's orbit be stable over thousands of years. Millions or billions, if you want life to evolve.
* that the moon stay invisible at all times -- never be illuminated enough by any sun to be visible.
* that the moon be wide enough in angular size to eclipse one sun for over a day!
If you read this paper, you see they settled on a moon the same mass as Kalgash but with the density of Saturn! How could such a system possibly arise?
"we found that the system is possible for short periods of time"
They state that their configuration is "stable for a few hundred years", and their graphs only extend to 400 years. The eclipse cycle in the story is 2049 years and has repeated enough times that people are starting to detect that it is fact repeating.
In reference to tidal forces from the Trey-Patru binary they state "(Though subsequent generations of the Kalgash people will face dangerous scenarios.)".
Their configuration actually has not been shown to be survivable for even one cycle.
P.S. I have crabs.
Could such a planet be habitable?
I'd always thought it would be too hot for (life as we know it, Jim)
that the planet's orbit be stable over thousands of years
Very low thousands is plenty if the timing is right. If anything say a few thousand years pre-Copernicus contained astronomical accounts that deviated wildly from what we "know" today, we'd put it in the same category as the artwork and accounts of the flat earth resting on the back of a giant turtle.
If you read this paper, you see they settled on a moon the same mass as Kalgash but with the density of Saturn! How could such a system possibly arise?
Gas Dwarfs?
http://blogs.discovermagazine....
As for the how, with 6 suns dancing around, you've got plenty of candidates to provide the required components, and lots of opportunity for freak events, collisions, etc.
Honestly, I think, after you add in 'freak occurrences' we'll eventually find some pretty spectacularly improbable planets.
Except that you are referring to classic multiple star systems that have a dynamic hierarchy of a binary tree. I don't recall what was the specific description of the arrangement of stars in Asimov's story, but it may have been different than that, either in explicit description or the by implications of the conditions on the planet's surface.
Ezekiel 23:20
And Mesklin: http://en.wikipedia.org/wiki/M...
is just a reduced form of math for those with limited talents in abstraction.
What exactly does the author mean by "short term" in this context? Many scientists talk about how life on earth has only been around for a relatively short period relative to the age of the universe. So, in theory, short-term stability may provide plenty of time for life to evolve to a level similar to our own.
It's not that it's a format that he dislikes; it's in a format that is cumbersome to read. There's a reason we moved away from stone tablets - formats are important.
MS Word is a pretty poor choice to distribute a read-only document. Even PDF has unnecessary cruft and overhead if it's not intended to be printed.
Just because you're paranoid doesn't mean there isn't an invisible demon about to eat your face
While I agree that a better format could have been chosen, I dislike the "not worth my attention" part. What does the format have anything to do with the content?
It's like saying "fuck classic movies because they're not 3D".
...gis sdrawkcab (usually not responding to ACs; don't bother posting as AC)
>What does the format have anything to do with the content?
The part of not being able to view the content possibly?
>It's like saying "fuck classic movies because they're not 3D".
More like, shit I can't watch this because it's all on BetaMax.
I really loved the movie. They made a book out of it? Cool! Gotta look it up!
http://www.imdb.com/title/tt00...
Like online document converters don't exist. My God, what are we going to do?
...gis sdrawkcab (usually not responding to ACs; don't bother posting as AC)
hey, there are australians here, don't bring logic and science into it, we no longer believe in them, so therefore you scientists must be wack jobs.
... that there is even a debate. Surely all of us sending transmits are not doing so in vain, especially when Saro has responded... twice! We will deliver the baby.