Risk Factors

2049 October 29 7:20 UT
Test Year 21, Day 340, 8:00 CST/16:00 MST
Tau, MIT – MRI Room

The MRI and PET scanning machines had been enhanced with instructions from the Gamblers, and had a resolution far better than when they had left the Earth. But the scans were not good. There were four tumors along Julian’s large intestine, and others spread throughout his torso. There was a small one just above his heart.

The biopsy was strange. The growth was a fairly typical benign colon variety and would not have spread by itself, but there was also a large block of Tau DNA in the cells that tested positive. A Tau virus had gotten into Marriner’s body and had not died. Instead, it had gotten into the pre-cancer cells and made them malignant. On Earth, it lacked two weeks from fifty-six years since he had been born. He had lived only forty-four.

The chemotherapy available to the Techers was limited. Cancer hadn’t been a priority since landing. The Gamblers had no stores of their own, but had provided the instructions to synthesize many drugs. The best Townsend, Sakhar, and the other biochemists could find took down the small tumors, with several massive doses that nearly killed Julian. But now the larger masses were inert and could be surgically removed. A low dose of a blocker drug would keep any remaining cancer cells dormant. But there was an incipient aneurism on his aorta, and he would not be able to handle the surgery necessary to repair it for several months. So Julian got used to his wheelchair and tried to relax, as the cast rehearsed his opera. They had all volunteered when they heard about his illness.

Tau Ceti Orbit, The Forge Asteroid

The Forge was, to a first approximation, the same as 1950 DA or the Pusher had been after a less than a year of colonization, although Gamble’s mining packages were rather faster in constructing than designs fifteen years older. But there was still the large solar array, the carbonyl-vapor metal processor, the focusing mirrors to burn out water and organics, the small living quarters next to a partially constructed iron shell, and the solar sail tug slowly adjusting its trajectory to bring it to Tau at a safe speed to orbit.

But 1950 DA and the Pusher had not had a large particle accelerator built nearby and flying in formation. The reactions to produce negative matter by the Zhang-Morbidini process require accelerating particular rare isotopes to one percent the speed of light, smashing them together, and catching everything but the neutrinos and the photons. Even in this configuration, it takes about ten to the twenty collisions to produce one negative proton and one negative electron. They need to be separated out and held, in isolation like antimatter. It had taken eight Earth months to build and test the accelerator with more prosaic reactions and ten days of accelerator time to produce that first negative atom. They got lucky: after two more weeks, they had three.

Now the accelerator could be used to smash these bits of negative matter together, with all due precautions given the side effects of missing a minus sign. Smashing negative matter together at high velocity produces a spray of particles, as would be expected: negative matter, negative antimatter, and little bits of matter and antimatter. Capturing and isolation is incredibly important, or the negative matter will annihilate off of random particles. The vacuum in the accelerator chamber was three orders of magnitude higher than the interplanetary space outside.

Getting two particular particles to hit each other, when each one is a proton or electron, is hard. It took another day of run-time to smash the first particles together. In the bare metal control room in the hab, Zhang was pleased when that day ended with seventeen negative hydrogens rather than three.

After two more days, they had a hundred thousand particles. The reaction speed had built up as there were more particles to collide into each other. Ten days into the generation process, they ran into their power limit: with the hundred megawatts available from the array, the maximum production rate was of negative mass was 100 milligrams a day. Even with that amount of material, it had been considered prudent to move the accelerator well away from both the testing lab, trailing a hundred kilometers behind on its own sail, and the living areas.

At the testing lab, a total of 10 milligrams of negative mass had arrived in magnetic bottles. Using remotes, the smiths followed the sequence that the Four had worked out in the first year, as it had been refined over the last two decades. They had a significant amount of negative helium and negative lithium, so Zhang specified the construction of minute grains of negative lithium hydride. These were each only ten nanometers wide and they were held by powerful electromagnetic fields. The next stage was exceptionally delicate.

A speck of normal matter was put into the system. The negative grains were charged and accelerated up to increase their mass, and sent through so that they just missed the normal one, forming a transient cylinder around it. Gravity pushed it to the center of the ring and compressed it. This entire process was a press to steadily push on the central grain with more pressure than exists in the center of most stars.

The grains, long past having a molecular structure, became electron degenerate, with a surface gravity high enough that more matter could be dribbled onto their surface. This was done at the same time as more negative mass was shipped over from the accelerator and added to the accelerated negative points. Over another month, a full three grams of both positive and negative matter had been added, and the grains exceeded neutron degeneracy. They, calmly and with no fuss, collapsed into quark-degenerate point masses. They were stable: the nature of their construction prevented Hawking radiation and quantum decay from siphoning off more than one percent of their mass over the age of the universe.

The plan had been to slow down the negative point masses, then put them next to the positive masses and watch them accelerate: the crudest of the possible ways to use negative matter as an engine. The slowing down did fine, as did the removal, separation, and storage of the different point masses in well-separated locations. Even though the testing center and the Forge were far apart (for this test the distance had been increased to a thousand kilometers), they waited until the hab was behind the rock to start. It was well that they did.

From telemetry analyzed after the fact, they saw the masses in the testing chamber be released and start to accelerate. They moved slowly: the masses were separated by a tenth of a millimeter, and they would only move at 2 microns per second squared. Then there was a corona discharge forming around the masses, the gamma-ray flux spiked, charged particles surged, and the bomb went off.

Six grams of matter (or negative matter) converting to energy is equivalent to ninety kilotons of TNT detonating, but it all comes out in gamma rays and pions and mesons. The structure of the testing station was instantaneously converted to plasma, which expanded like a bomb but absorbed the gammas. It had cooled to merely soft X-rays by the time it became transparent. Each square meter of the rock, the accelerator’s surface, and the solar array absorbed sixty joules of energy, closely followed by a blast of plasma that nearly overwhelmed the magnetic bubble shielding of the main installation. By the time the hab came out of eclipse three minutes later, there was nothing left but a hole in the interplanetary medium. Most of the solar array was fried and useless.

They learned what had happened. Quantum mechanical fluctuations meant that there was a leakage zone on the surface of the mass: jitter of a few microns for a tenth-gram mass. Anything smaller tended to collapse from the oscillations. In isolation or even in normal matter, the points they had used were stable. But when there was a point of opposite sign in the vicinity, the masses started to slowly annihilate each other. It had been a slow process until a charge difference between the masses had pulled them together over the containment. Then everything had annihilated at once.

The good news was that they could simply move the masses further apart and make them larger, although that would slow down construction. The bad news was that they had lost a portion of the stockpile of point masses and it would take even longer to build the larger ones. The Forge’s power supply would be expanded drastically from Gamble’s solar panels once they were in orbit around Tau, and then they could manufacture enough negative mass to use it itself as a power source. But it would be at least six months before they could make an engine large enough to move one of the Nervs at a meaningful acceleration.