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rfmcdonaldAuthor and scientist Charles Pellegrino has sketched out in the technical appendices to a couple of his science-fiction novels the broad outlines for an antimatter-fueled starship capable of exceeding 90% of the speed of light. The late Robert Forward's laser-powered light sails might be somewhat more practical inasmuch as the engines--the solar-orbit lasers--would remain in our own planetary system where they could be readily repaired, but Pellegrino's superficially plausible near-lightspeed starships have the advantages of speed and mobility.
The problem with Pellegrino's starships doesn't seem to lie so much in their design as in their implications. If it's trivially easy for a suitably advanced civilization to build his starships, then relativistic bombardments of planets from light-years away become possible. The physics are simple enough: Accelerate an object the size and mass of an ashtray to a substantial fraction of the speed of light, do nothing to allow it to accumulate a vast amount of energy, bring it to a stop via a collision, and observe the resultant discharge of energies equivalent to a multi-megaton thermonuclear bomb. The larger the object accelerated by the starship the greater the explosion.
The Killing Star introduces these starships to humans, and then goes on to describe the obliteration of human civilization through a surprise relativistic bombardment of the Earth and the other offworld population centres of humankind. Our neighbours at Alpha Centauri, it seems, rather than risk a first contact that could have ended badly, decided to do away with us in order to save our worlds. Remarkably, Pellegrino's sequel, Flying to Valhalla, manages to come to even more depressing conclusions about the possibilities for interstellar-capable civilizations to co-exist.
Earth has been a radio source for a century. Why isn't Earth a pitted wasteland? Two possibilities come to mind.
I prefer the latter possibility. I think.
The problem with Pellegrino's starships doesn't seem to lie so much in their design as in their implications. If it's trivially easy for a suitably advanced civilization to build his starships, then relativistic bombardments of planets from light-years away become possible. The physics are simple enough: Accelerate an object the size and mass of an ashtray to a substantial fraction of the speed of light, do nothing to allow it to accumulate a vast amount of energy, bring it to a stop via a collision, and observe the resultant discharge of energies equivalent to a multi-megaton thermonuclear bomb. The larger the object accelerated by the starship the greater the explosion.
The Killing Star introduces these starships to humans, and then goes on to describe the obliteration of human civilization through a surprise relativistic bombardment of the Earth and the other offworld population centres of humankind. Our neighbours at Alpha Centauri, it seems, rather than risk a first contact that could have ended badly, decided to do away with us in order to save our worlds. Remarkably, Pellegrino's sequel, Flying to Valhalla, manages to come to even more depressing conclusions about the possibilities for interstellar-capable civilizations to co-exist.
Earth has been a radio source for a century. Why isn't Earth a pitted wasteland? Two possibilities come to mind.
- Starflight is technically much more difficult than we have imagined.
- Environments capable of supporting life forms capable of intelligence are rare.
I prefer the latter possibility. I think.
