A “Bussard ramjet,” a type of starship popularized in science fiction, is technically feasible, but the engineering challenges are overwhelming, according to recent research.

A Bussard ramjet is a type of starship hypothesized in 1960, which became a staple of science fiction. The ramjet operates by sweeping interstellar hydrogen as fuel using a magnetic field.

Researchers now say the magnetic net would need to be at least 4,000 kilometers wide.


Spaceships with warp drives are unnecessary to colonize a whole galaxy, according to recent computer simulations

George Dvorsky at Gizmodo:

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 new paper [in The American Astronomical Society], 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.

The simulation starts with a single technological civilization in a galaxy like ours, and results in the entire inner galaxy being settled in 1 billion years. “That sounds like a long time… ” says Dvorsky (um, because it is?) “… but it’s only somewhere between 7% and 9% the total age of the Milky Way galaxy.”

By comparison, writing was invented a mere 6,000 years ago.

The simulation throws around some other big numbers:

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, perhaps fast ships using solar sails powered by giant lasers, or just very long-lived ships that can make journeys of 100,000 years running on ordinary rockets and gravitational slingshots from giant planets.”…

… our “galaxy is over 10 billion years old, so it could have happened many times over, even with those parameters.”