I have never yet successfully watched Avatar, and this despite the fact that it was filmed in the city where I live, and its 3,862 sequels are being developed here right now. I tried watching it. Twice. And fell asleep both times.
You can guess that I didn’t think too much of the movie. It presented to me as Pocahontas meets Dances With Wolves meets a Vietnam War protest, complete with the cliché anti-war version of what the military are meant to be like. Saccharine, judgemental, and who says that future society, centuries hence, is going to go in a direction that offers social commentary on the ills of mid-twentieth century society?
But I also had problems with the technology, which was trying too hard to be ‘realistic’. One of the annoyances was the starship. This was a visual tour de force, and it had a solid technical basis in an engineering study done by Charles Pellegrino and Jim Powell for a starship able to accelerate to 92 percent light-speed via an antimatter beam-core drive.
Theoretically such a drive is plausible – the physics of it are well understood. The problem is actually building one, given that any material substance can’t withstand the energies involved. Even the fuel – anti-hydrogen – can’t be handled by normal pipes and tanks. That implies magnetic containments.
To me there was much that was just too casual about the whole idea, which Pellegrino dubbed ‘Valkyrie’, and which Cameron portrayed on a significantly larger scale. It introduced a new concept; towing – the motors were ahead of the ship, creating huge efficiencies in mass-weight ratio. That was cool. But the difficulties of handling antimatter were essentially hand-waved; the idea was that anti-hydrogen could be reduced to near absolute zero temperatures (0.0005° K) and become snow, making it easier to transfer and store. Theoretically, quantum effects mean the matter-antimatter reaction won’t happen at that temperature. It hasn’t been tested. And you’d need only one glitch in your magnetic containment, and …. Boom. ‘Ooh look, a second sun.’ The equation involved is the one we know so well – E = MC<exp>2.
Getting that much antimatter is another challenge; it can be made, but thanks to Dr Einstein’s equation, the energy needed is colossal. Production also isn’t efficient – about 50 percent. At that level, making 50 tons of antimatter would require the whole of Earth’s current energy production over a 40 year period (1.8 x 10 <exp>22 joules, since you ask).
Another hand-wave was the solution to the problem of interstellar particles at lightspeed. Space is, essentially, a vacuum, but there are enough stray particles of hydrogen and helium, and a few other things, to be a problem. If you’re moving at lightspeed, they present as hard radiation (it makes no difference whether it’s the particle or you that’s moving). The Valkyrie answer was to create a circulating shield of particles ahead of the ship to act as a buffer. These were collected and re-used. Exactly how that could work with the efficiency needed, however, didn’t seem plausible to me. The Avatar starship, given its scale, would require thousands of tons of antimatter.
All of which, to me, rather blew the suspension of disbelief. So will I be watching the Avatar sequels? Probably not.
Copyright © Matthew Wright 2019