kottke.org posts about George Dvorsky

What's the deal with Game of Thrones' unpredictable winters?May 03 2012

George Dvorsky details five possible scientific explanations for Westeros' seasons of unpredictable length. A "wobbly planetary tilt" is one possible reason:

In the episode "The Kingsroad," we learn that Westeros has at least one moon. It's very possible, therefore, that they have a very small or distant moon, that is causing a variable tilt in their planet's rotational axis.

It's interesting to note that, according to legend, Westeros used to have two moons, but "one wandered too close to the sun and it cracked from the heat" pouring out a thousand thousand dragons. Well, dragons aside, it's conceivable that some kind of cataclysmic celestial event could have wiped out their second moon, which would have thrown their planet's rotational axis out of whack.

Let's destroy Mercury and build a Dyson sphereApr 09 2012

George Dvorsky argues that if we wanted to, humanity could get a Dyson sphere up and running in a few decades.

The Dyson sphere, also referred to as a Dyson shell, is the brainchild of the physicist and astronomer Freeman Dyson. In 1959 he put out a two page paper titled, "Search for Artificial Stellar Sources of Infrared Radiation" in which he described a way for an advanced civilization to utilize all of the energy radiated by their sun. This hypothetical megastructure, as envisaged by Dyson, would be the size of a planetary orbit and consist of a shell of solar collectors (or habitats) around the star. With this model, all (or at least a significant amount) of the energy would hit a receiving surface where it can be used. He speculated that such structures would be the logical consequence of the long-term survival and escalating energy needs of a technological civilization.

Needless to say, the amount of energy that could be extracted in this way is mind-boggling. According to Anders Sandberg, an expert on exploratory engineering, a Dyson sphere in our solar system with a radius of one AU would have a surface area of at least 2.72x1017 km2, which is around 600 million times the surface area of the Earth. The sun has an energy output of around 4x1026 W, of which most would be available to do useful work.

The downside: we'd have to part with Mercury to do it.

And yes, you read that right: we're going to have to mine materials from Mercury. Actually, we'll likely have to take the whole planet apart. The Dyson sphere will require a horrendous amount of material-so much so, in fact, that, should we want to completely envelope the sun, we are going to have to disassemble not just Mercury, but Venus, some of the outer planets, and any nearby asteroids as well.

At Forbes, Alex Knapp explains why Dvorsky's scheme and timeline might not work.

I emailed Astronomer Phil Plait about this project, who told me in no uncertain terms that the project doesn't make sense.

"Dismantling Mercury, just to start, will take 2 x 10^30 Joules, or an amount of energy 100 billion times the US annual energy consumption," he said. "[Dvorsky] kinda glosses over that point. And how long until his solar collectors gather that much energy back, and we're in the black?"

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