(Roughly) Daily

“I’m sure the universe is full of intelligent life. It’s just been too intelligent to come here.”*…

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A new computer simulation shows that a technologically advanced civilization, even when using slow ships, can still colonize an entire galaxy in a modest amount of time. The finding presents a possible model for interstellar migration and a sharpened sense of where we might find alien intelligence.

Space, we are told time and time again, is huge, and that’s why we have yet to see signs of extraterrestrial intelligence. For sure, the distances between stars are vast, but it’s important to remember that the universe is also very, very old. In fact, I’d go so far as to say that, in terms of extremes, the Milky Way galaxy is more ancient than it is huge, if that makes sense. It’s for this reason that I tend to dismiss distances as a significant variable when discussing the Fermi Paradox—the observation that we have yet to see any evidence for the existence of alien intelligence, even though we probably should have.

New research published in The American Astronomical Society is bolstering my conviction. The new paper, co-authored by Jason Wright, an astronomer and astrophysicist at Penn State, and Caleb Scharf, an astrobiologist at Columbia University, shows that even the most conservative estimates of civilizational expansion can still result in a galactic empire.

A simulation produced by the team shows the process at work, as a lone technological civilization, living in a hypothetical Milky Way-like galaxy, begins the process of galactic expansion… Things start off slow in the simulation, but the civilization’s rate of spread really picks up once the power of exponential growth kicks in. But that’s only part of the story; the expansion rate is heavily influenced by the increased density of stars near the galactic center and a patient policy, in which the settlers wait for the stars to come to them, a result of the galaxy spinning on its axis.

The whole process, in which the entire inner galaxy is settled, takes one billion years. That sounds like a long time, but it’s only somewhere between 7% and 9% the total age of the Milky Way galaxy.

As noted, the new model is constrained by some very conservative rules. Migration ships are launched once every 10,000 years, and no civilization can last longer than 100 million years. Ships can travel no farther than 10 light-years and at speeds no faster than 6.2 miles per second (10 kilometers per second), which is comparable to human probes like the Voyager and New Horizons spacecraft. 

“This means we’re not talking about a rapidly or aggressively expanding species, and there’s no warp drive or anything,” said Wright. “There’s just ships that do things we could actually manage to do with something like technology we can design today… Even under these conditions, the entire inner part of the simulated galaxy became settled in a billion years. But as Wright reminded me, our “galaxy is over 10 billion years old, so it could have happened many times over, even with those parameters.”…

A new simulation published by the American Astronomical Society suggests that aliens wouldn’t need warp drives to take over an entire galaxy in (relatively) short order, as George Dvorsky (@dvorsky) explains.

[Image above: Andromeda Galaxy, source]

* Arthur C. Clarke


As we spread out, we might spare a thought for Jacobus Cornelius Kapteyn; he died on this date in 1922. An astronomer, he used photography and statistical methods to determine the motions and spatial distribution of stars (especially with the Milky Way), the first major step after the works of William and John Herschel. He introduced absolute magnitude and color indexing as standard concepts in cataloguing stars.

Kapteyn was also among the first to suggest the existence of dark matter (which he deduced from examining stellar velocities).


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