Reporters were calling me last week about a paper that turned up on astro-ph, Dark Matter and the Habitability of Planets, by Hooper and Steffan.
Their thesis is that in regions where the density of non-baryonic dark matter is high, an abundance of dark matter particles scatter off the nuclei in the planetary interiors, and get trapped inside a planet, where they wheel on rapidly precessing orbits through the near-transparency of the rocky firmament. Weakly interacting dark matter likely constitutes its own anti-particle, and so when trapped WIMPS encounter each other, they annihilate, producing heat. In The Five Ages, we drew on this process to keep the white dwarfs and the neutron stars shining weakly through the dark expanses of the Degenerate Era.
In Hooper and Steffan’s picture, WIMP annihilation isn’t wimpy at all. In fact, they lean on the process to produce enough heat to keep the water liquid and the planetary surfaces habitable, even in the absence of a parent star.
Sounds like a long-shot to me, but where the WIMP annihilation mechanism might be quite useful is in powering geological activity for the duration. There are plenty of potentially habitable planets orbiting low-mass M-dwarf stars which have staggeringly long main-sequence lifetimes. The long-term habitability hitch for the planets orbiting these stars is not the loss of stellar radiation, but rather cooling of the planetary interior and the attendant shut-down of mantle convection. A cold planet like Mars doesn’t maintain a dynamo, it has no magnetic field to speak of, and its atmosphere is therefore subject to the ravages of solar coronal mass ejections. It’d really be quite nice if WIMP annihilation could keep things ticking long after the heat of formation and the heat of radioactive decay have e-folded into oblivion.
The discovery that the expansion of the universe is accelerating came just about the time that my book with Fred Adams, The Five Ages of the Universe, was going to press. So we were significantly out-of-date right from the start. Some of the bigger-picture details in our narrative, such as gravitationally-based computation, almost certainly won’t occur if all of the other galaxies are all accelerated out beyond our causal horizon, but all the events dealing with stars and planets are unaffected by the presence of dark energy.
A recent paper by Avi Loeb (arXiv:1102.0007) shows that astronomers of the extremely distant future will be able to unravel large-scale cosmological insights by making careful velocitiy measurements of the faint escaping halo of red dwarf stars that will surround Milkomeda, the merger remnant of upcoming Milky Way-Andromeda collision.
One might reasonably wonder whether they might have an easier time by simply reading the old issues of Astrophysical Journal. Given, however, my general inability to curate the computer files that I generated in the 1990s, its a good bet that in a trillion years it’ll be considerably easier to just go out and do the observations.
I don’t like AdSense-style ads, and I’m contemplating shelling out $29.95 so that readers of Molybdos and The Five Ages won’t have to see them. If you’re seeing an ad related to this post, it’s courtesy of WordPress.com, not yours truly.
It’s not that I’m against advertising. I like looking through the ads in the New York Times Style Magazine — ads that impart a vicarious aspirational buzz, I especially approve of. This past summer, when I was in Paris, I saw the whole machinery of the advertising industry in full swing. At mid-morning, in the midst of my seminar on Gliese 876, the tranquility of the Paris Observatory grounds was abruptly shattered by the diesel roar of generators and the clangorous shouts of workmen.
The tree-lined promenade along the Paris Meridian leading up to south-facing exposure of the grand Seventeenth-century observatory had been rented out to Lacoste in order to stage a runway show. The interior of the observatory was, additionally, off-limits to astronomers, as there was a champagne reception in the Cassini Room in association with the show.
Having seen the writing on the wall first hand, I spent some more time looking into Demand Media’s business model. It seems almost alarmingly feasible to set up a content farm sourced with NLG-generated articles. In fact — and here’s the tie in to The Five Ages — I think the entire universe could very well be a content farm…
I learned yesterday (in the course of a conversation with Philip regarding stocks with potentially perilous valuations resembling that of CRM) about the concept of content farming, and the business model underlying Demand Media. I have to say, I found this article from Wired to be absolutely fascinating.
At the moment, it appears that Demand Media is relying on humans to generate their content. Their code parses frequent search-engine queries, and commissions endless “how to” and “top ten” pieces. While the writers of their articles appear to be real humans, the article assignments are done on a completely automated, completely algorithmic basis.
Clearly, the next step is to dispense with the actual human writers and commission computers to write the content. Based on our work with automated planet discovery and article generation using BAM, it’s pretty clear that NLG algorithms are not too far from being able to slip past Demand Media’s copy editors and quality control. Given that a lot of the necessary tools are open source, It looks like there might be a window of opportunity to outsource their article writing to computers before they get wise and start doing it themselves.
Once NLG is capable of generating something on order of the News of the World, I think that a Google-killer will be spawned.
It occurs to me that the redshift at which the Dark Energy starts to dominate is similar to the redshift at which the first technological civilizations might reasonably have emerged (assuming that the Earth is at least a reasonable baseline example of a “standard” trajectory.)
Might there be a connection?
Fifty years on, with the commisioning of the Allen Telescope Array, the seti enterprise continues to be long radio.
From an unscientific perspective, though, radio seems to be on the way out. I do listen to NPR all the time while I’m driving around, but the KUSP transmitter is, I believe, rather low-power. The pledge drives generally seem to fall short of their goals. Certainly, KUSP is less powerful than the 140-mile distant WLS transmitter that I tuned into with my clock radio every night in 7th grade while doing my homework.
When I moved away from Illinois, I didn’t take my clock radio.
By 1800, the mathematical sophistication evident in Laplace’s Mécanique Céleste was more than sufficient to support a profound understanding of Maxwell’s equations. The equations themselves, however, came more than fifty years later, and what might qualify as the first radio broadcasts came in the 1890s. Nearly seventy years then elapsed before the advent of interstellar seti.
Speculation of the day: we’ve got the mathematical sophistication to understand the actual mechanism of communication, but we don’t yet know the physics, and we certainly don’t have the technology.