Going Interstellar (collection)

It has been suggested that one source of antiparticles in nature is black holes. The process would work as follows. Protons have a higher mobility than electrons. In the case of a black hole immersed in a tenuous neutral plasma composed of electrons and protons, more protons than electrons might tend to disappear into the event horizon of a cosmic black hole. This would produce a positive charge on the black hole and a large electric field. If the field becomes enormous, a vacuum instability could be produced. This vacuum instability might result in the production of matter/antimatter pairs. It is conceivable that in the early universe, the preferential gathering of protons into black holes and the resulting positive charge on these singularities might have resulted in more negatively-charged antiprotons being absorbed by them than positively-charged protons (since opposite charges attract). But what then happened to the surplus positrons?

Another way that matter/antimatter pairs can theoretically be produced by black holes is Hawking Radiation, named after the world-famous British theoretical physicist. Black holes of all sizes may have been created in an early stage of the universe. As black holes age, they ultimately evaporate with the less massive ones suffering this fate sooner that their more massive compatriots. Primordial black holes of asteroid-planet mass are theoretically evaporating during the current universal epoch. As a black hole evaporates, much of its contained energy is radiated away. Some of this radiation should be converted to matter/antimatter pairs.

Closer to home, it has been noted that even stable, main-sequence stars like our Sun may be antimatter factories. In 2002, satellite observations of solar flares indicated that a large flare may release as much as half a kilogram of antimatter. Apparently, solar flares in some unknown manner sort particles by mass so that many of the antiparticles unexpectedly survive their passage through dense solar layers.

Even closer to home and more surprising are satellite observations of terrestrial lightning discharges. In 2009, it was reported that during its first fourteen months of operation, the NASA Fermi Gamma Ray Space Telescope had detected gamma ray bursts associated with seventeen lightning discharges. The positrons were detected in two of these.

The Best Existing Human-Constructed Antimatter Factories

Our most energetic particle accelerators can accelerate sub-atomic electrically charged particles to nearly the speed of light. When these energetic particle beams impact a target, some of the beam energy is converted to particle/antiparticle pairs.

When Robert Forward wrote his US Air Force report on advanced propulsion in 1983, there were three antimatter factories in the world. All were proton accelerators. One was in Russia, another was CERN, and the third was the Tevatron at the Fermi National Accelerator Laboratory near Chicago. None of these machines can be considered “small” by any standard. The Tevatron, for example, has a four mile circumference and is equipped with more than one thousand superconducting magnets operating at temperatures close to absolute zero.

Accelerated protons in the Tevatron circle the ring almost fifty thousand times per second at a peak velocity of 99.99999954 percent the speed of light in vacuum. To protect the surrounding environment from stray radiation, the Tevatron tunnel is 25 feet below ground.

Operating continuously, the Tevatron could produce and temporarily store, at enormous expense, about 1 nanogram per year of antiprotons. If all three of these devices were to be devoted to antimatter production and operated continuously, we might have a gram of the stuff after one hundred million years. We need to do a bit better for star flight!

Huge and imposing as it is, the Tevatron must be considered obsolete when it is compared to its cousin the Large Hadron Collider (LHC) at CERN. The LHC has a radius of over two and half miles and is equipped with 9,300 magnets for beam bending and focusing.

Within the fully operational LHC, particle beams will circulate 11,245 times each second. There will be up to six hundred million particle collisions per second and the best vacuum in the solar system will be maintained within this device.