kilometers. A hundred million times further away than the moon is from Earth.”
Kenzie waved that away. “And the nearest Earth-like world? How far to that?”
Liu said, “The nearest reasonable candidate is sixteen light-years away.”
“Oh, that all? OK, so how do we get there? I’d guess from our previous discussion about the domes on Mars that you guys wouldn’t think we could run a space mission, unsupported, of more than a few years. A decade, tops. So that’s the timescale. Have I got that right? So how do we get to the stars in a decade? I take it chemical rockets, the shuttle and the Saturn, are out. If it took three days for Apollo to fly to the moon—”
Patrick grinned. “Only three million years to Earth II!”
Glemp said, “An alternative is to use electricity to throw ions, charged atoms, out the back as your exhaust. A much higher exhaust velocity gives you a better performance . . .”
But Liu quickly dug out a whiskery study that suggested that even an ion rocket would need the equivalent of a hundred million supertankers of fuel to reach Alpha Centauri in a century or less.
“Nuclear engines, then,” Glemp went on. “Back in the 60s NASA developed a ground-based test bed of a fission engine—hydrogen heated up by being passed through a hot nuclear fission pile and squirted out the back . . .” NERVA had worked. But again, as they paged through theoretical studies from the archives, they quickly found that the fuel demands for an interstellar mission on the timescales they required were impossibly large. They did find some useful material, such as a NASA study on lightweight nuclear engines meant to power a generation of unmanned explorers of Jupiter’s moons, probes that never got built; Glemp and Liu flagged such material for further study.
Glemp said, “Look—you don’t actually need any fuel at all to reach the stars. You can use a solar sail . . .” A sail kilometers across, made of some wispy, resilient substance that would gather in the gentle, unrelenting pressure of sunlight, of solar photons bouncing off a mirrored surface. “Such a craft would take mere centuries to reach the stars.”
“Too long!” Kenzie snapped. “We’re drifting here, guys.” He pushed back his chair and walked around the room. He paused briefly by the kids, who, with Harry patiently filming them, were acting out a siege of their plastic fort. Kenzie said, “Captain Kirk never had this trouble. Where’s a warp drive when you need one?”
They laughed, all save Liu, and Patrick wondered if that was because he’d never heard of Star Trek. But the Chinese said, “That of course would be the solution. A faster-than-light drive.”
“No such thing exists,” said Kenzie.
Jerzy Glemp said firmly, “No such thing can exist. According to Einstein the speed of light is an absolute upper limit on velocity within the spacetime of our universe.”
“True,” Liu said. “But spacetime itself is not a fixed frame. That is the essence of general relativity. In the early moments of the universe, all of spacetime went through a vast expansion. During the interval known as inflation, that expansion was actually faster than light.”
Patrick was lost, but Jerzy Glemp was intent. “What are you suggesting? That we ride a bubble of inflating spacetime?”
“I don’t know,” Liu Zheng said. “I have a faint memory, of a study long ago . . . May I check it out?” Kenzie waved his permission, and Liu began to scroll through screens of references and citations.
Kenzie said, “You know, maybe we need to step aside from the core problem for a minute. We are after all talking about starting up a space program here in Colorado. However we travel to the stars we’re going to need launch facilities to get to orbit in the first place: gantries, blast pits, liquid oxygen factories, communications, a Mission Control, the whole Cape Canaveral thing. Jerzy, we need to find ourselves some space engineers.
Kenzie waved that away. “And the nearest Earth-like world? How far to that?”
Liu said, “The nearest reasonable candidate is sixteen light-years away.”
“Oh, that all? OK, so how do we get there? I’d guess from our previous discussion about the domes on Mars that you guys wouldn’t think we could run a space mission, unsupported, of more than a few years. A decade, tops. So that’s the timescale. Have I got that right? So how do we get to the stars in a decade? I take it chemical rockets, the shuttle and the Saturn, are out. If it took three days for Apollo to fly to the moon—”
Patrick grinned. “Only three million years to Earth II!”
Glemp said, “An alternative is to use electricity to throw ions, charged atoms, out the back as your exhaust. A much higher exhaust velocity gives you a better performance . . .”
But Liu quickly dug out a whiskery study that suggested that even an ion rocket would need the equivalent of a hundred million supertankers of fuel to reach Alpha Centauri in a century or less.
“Nuclear engines, then,” Glemp went on. “Back in the 60s NASA developed a ground-based test bed of a fission engine—hydrogen heated up by being passed through a hot nuclear fission pile and squirted out the back . . .” NERVA had worked. But again, as they paged through theoretical studies from the archives, they quickly found that the fuel demands for an interstellar mission on the timescales they required were impossibly large. They did find some useful material, such as a NASA study on lightweight nuclear engines meant to power a generation of unmanned explorers of Jupiter’s moons, probes that never got built; Glemp and Liu flagged such material for further study.
Glemp said, “Look—you don’t actually need any fuel at all to reach the stars. You can use a solar sail . . .” A sail kilometers across, made of some wispy, resilient substance that would gather in the gentle, unrelenting pressure of sunlight, of solar photons bouncing off a mirrored surface. “Such a craft would take mere centuries to reach the stars.”
“Too long!” Kenzie snapped. “We’re drifting here, guys.” He pushed back his chair and walked around the room. He paused briefly by the kids, who, with Harry patiently filming them, were acting out a siege of their plastic fort. Kenzie said, “Captain Kirk never had this trouble. Where’s a warp drive when you need one?”
They laughed, all save Liu, and Patrick wondered if that was because he’d never heard of Star Trek. But the Chinese said, “That of course would be the solution. A faster-than-light drive.”
“No such thing exists,” said Kenzie.
Jerzy Glemp said firmly, “No such thing can exist. According to Einstein the speed of light is an absolute upper limit on velocity within the spacetime of our universe.”
“True,” Liu said. “But spacetime itself is not a fixed frame. That is the essence of general relativity. In the early moments of the universe, all of spacetime went through a vast expansion. During the interval known as inflation, that expansion was actually faster than light.”
Patrick was lost, but Jerzy Glemp was intent. “What are you suggesting? That we ride a bubble of inflating spacetime?”
“I don’t know,” Liu Zheng said. “I have a faint memory, of a study long ago . . . May I check it out?” Kenzie waved his permission, and Liu began to scroll through screens of references and citations.
Kenzie said, “You know, maybe we need to step aside from the core problem for a minute. We are after all talking about starting up a space program here in Colorado. However we travel to the stars we’re going to need launch facilities to get to orbit in the first place: gantries, blast pits, liquid oxygen factories, communications, a Mission Control, the whole Cape Canaveral thing. Jerzy, we need to find ourselves some space engineers.
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