Massless drive, science fiction story to end all stories on

Dedicated to Larry Niven.

In 2117 the inertialess drive was finally perfected. It had been tested in the Joint Space Exploration Vacuum Lab over a period of four years, years in which the research team had been dragged through devastating emotional lows and euphoric highs. The Consortium of Space Venturing Nations had contributed more than a trillion dollars in research funding to create the volume known, perhaps somewhat melodramatically, as “hypervacuum.” In the hundred cubic meters of the controlled facility, there was zero matter, or as the leader of the research unit more carefully put it, “Zero matter detectable to our instruments.” Even quantum fluctuations were suppressed within.
       If the experiment were successful, it would create a brutal explosion. For this reason, while the scientists controlled the experimental apparatus from Madrid, the hypervacuum chamber itself was located in extreme isolation at the North Pole.
       The vast resources committed to the project finally created the long-sought result: In the controlled facility, the inertial dampener was activated. As the rest of the team watched the monitors with bated breath, the team leader extended her finger and pushed a button. Thousands of miles away in the hypervacuum chamber, a fragile metal cylinder the size of a pencil moved forward and gently tapped the six-ton engine. An immeasurably short instant later the engine had smashed into the far wall of the chamber. No human eyes witnessed that; the violence of the ensuing explosion vaporized the video cameras instantly, along with the hypervacuum chamber and dozens of square miles of Arctic ice. The cameras showed only static, but satellite images of the pole conveyed the good news to the research team.
       With screams of joy they leapt to their feet! It worked! The engine’s inertial mass had been eliminated; there was no resistance to acceleration! A thousand-kiloton spaceship could be accelerated to just below lightspeed with a mere tap from a feather. Finally, the stars were within reach of the human race!
       After a couple of days of uproarious partying, the American members of the research unit had returned to the US to meet with the President. “Remind me what this does,” the President said. “I read the briefing a few weeks ago but I’m rather busy. What’s that thing about ‘suppressing inertial mass’?”
       A team member responded, “Basically, the object, um, doesn’t weigh anything. By suppressing inertial mass, the device allows us to accelerate any object, no matter how large, to just under lightspeed, with veritably zero energy input.”
       “And what is ‘just under lightspeed’?”
       “A few decades ago physicists discovered that time and space are quantal–”
       “Basically lumpy, right?” asked the President. “Not smooth.”
       “Exactly. So while matter can’t go at lightspeed, the quantal nature of space and time make it possible to have a speed of one quantal velocity unit below lightspeed.”
       “But what about Einstein?” the President asked. “I thought the briefing said…”
       “Einstein’s equations, it turns out, are only continuous approximations to the discrete reality.”
       “Ah, of course.”
       A few years later the first starship had been constructed in orbit. A new inertialess engine was installed. Video cameras outside the ship were arrayed to convey the momentous event to Earth. A theoretical physicist whose work had been crucial to the project had been granted the right to launch the ship. He floated near it in a spacesuit, linked by radio to the crew within. A hopeful planet stared at innumerable TV and computer screens, waiting for the dream of centuries to finally be realized.
       In the ship’s control room, the captain gave the order.
       The engineer engaged the drive.
       Outside the ship, the scientist reached out and tapped the hull.
       Nothing happened, except an annoying vibration throughout the vessel.
       Furious double-checking of the engine. No problems detected.
       “Oh, man, I just thought of something,” said the engineer.
       “What?” asked the Captain.
       “Well, this engine effectively makes the ship massless, right? So even the slightest contact with any other object, no matter how small, will provide the highest possible acceleration…”
       “Obviously. That’s why we should be headed to Proxima Centauri at just under lightspeed right now.”
       “Right, Captain,” said the engineer. “It’s just that space isn’t actually space. It contains about one randomly darting hydrogen atom per cubic meter.”
       “Oh fuck,” said the captain.

* * * * * * * * *


1) If you’re not familiar with the good ole “inertialess drive” from various past science fiction works, suffice it to say that one of the classic workarounds to the vast distances between stars wouldn’t work, even taken on its own terms.
2) Dedicated to Larry Niven because Niven’s Laws for Writers includes “Stories to end all stories on a given topic, don’t.” Heh.
3) I don’t know how much energy a six-ton mass colliding with a solid object at “just under lightspeed” would actually have. Enough to vaporize the Earth, for all I know. But that would ruin the fun. Or anyway, that’s a different kind of SF story. In any case, tapping a million-ton starship with a feather and having it zip off at the speed of light would violate physical conservation principles – like, ya know, the conservation of energy – up the wazoo.