Monthly Archives: September 2010

I don’t have time for a post, but man, this is exciting.

Astronomers have discovered an Earth-like planet in the “Goldilocks Zone” of its solar system. Gliese 581g is the sixth planet of the Gliese 581 system discovered to date, and the most promising of them all (others have received media attention for their size/composition, or location, but until now none have been squarely in the middle of the habitable zone).
More info from Science magazine; the paper itself will be in the next Astrophysical Journal.

In my opinion, Steve Vogt is getting carried away, misquoted, or just trying to make a name for himself with that “100% chance” soundbite; I haven’t heard anybody claim that the *only* prerequisite for life is a water-friendly temperature, and (although I’m no xenobiologist) the fact that 581g is a ribbon world doesn’t inspire confidence.

Still, this is the best shot at finding extraterrestrial life we’ve ever had. In the words of a friend-of-a-friend: “This is the coolest f***ing time to be alive.”

[EDIT] The fact that Gliese 581g is tidally locked is probably a good sign, as Vogt explains in the Space.com article. This provides more of a range of temperatures, from the blazingly-hot side facing the star to the frozen dark side. In between, there must therefore exist a fairly wide zone of Earthlike “Goldilocks” temperatures. A planet that rotates with respect to its sun has a much narrower range of temperatures, lowering the odds (although there is variation from the poles to the equator, of course!)

By the way, Space.com needs to work on their fact-checking. Mercury isn’t tide-locked, as scientists have known for decades [NASA].

Dissociated Press is a program included with the popular source-code editor Emacs. When run on a text file, it generates hilarious free-associations (see the link for details.)

It’s a wonderful toy, but it’s particularly good on something as rambling as Robert Penn Warren’s prose.

Behold:

I suppose that Anne, and juicy while Anne was inclined to bone and
muscle under flesh. Lois looked edible, and you knew it!" I
exclaimed, "I ought to have known it! It had to be."
"If you can guarantee results like that," I said, "you ought to have
it.
So the poor bastard had gone to the Other stroked the big leather
couch. The discomfort was due, in part at least, to the fact that the
summer, and the world, would ever end. But that morning when Anne
said that she wasn't accustomed to hear anything in pants talk like
that. Not that she didn't try to persuade me, but I got back, late at
night, and went to bed. The condom on the park path, the twitch in
the old bugger a little extra time before I popped the question to
him. He went out into the hal, Mr. Simms following. While Mr.
Simms locked the door, Cass said to him, for to fool. Well, this time
I'm going to fool somebody. I'm getting out of this race because you
admire his oratory."
"Ain't it?"
He didn't say anything to that.


I’ve recently dreamed up a consistent model of time travel specifically designed to allow for good science fiction.

Up until now, I’ve typically used a branching-timeline model for the sake of simplicity, but it leaves much to desire in the way of plot: each time traveler finds themselves in their own, separate timeline, and there is eventually very little point in killing Hitler because he’s still alive in the original. To remedy that, I now introduce… [drumroll….]

The Ripple Model:
The central idea is an old cliche in lousy science fiction: you change the past, and the change propagates through the timeline until it hits the present. In most cases, it leads to absurdities like Back to the Future (“Oh my gawd, I’m fading! I have only hours of vaguely-defined metatime to make sure my parents meet, thereby leading to my conception, which is apparently not already guaranteed because only I have free will in this movie!”)

However, this approach can be made rigorous. Consider the following:

You leave 2010 and appear instantly (meaning that no subjective time passes) in 1930 in Germany. You shoot Hitler and immediately leave for France, 1940. Twenty seconds later, the world changes around you: the war-torn nation is replaced by a happy pastoral scene, but you are unaffected because your own history (starting from 2010 and including the time travel) is intact. You jump to the present, and find that WWII still happened. Seventy seconds later, the encyclopedia entry in front of you disappears, but you hardly notice, because a tiny fraction of a second after that, the ripple swallows your own remaining history and you disappear. Nearby, an alternative version of you that has never heard of Hitler or WWII carries on.
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