The Scientific Truth Behind Spiderman 2

Spiderman 2 was undoubtedly fascinating – the characters, plot, and special effects in the movie were inarguably impressive. However, according to Prof. Henry Greenside, there are other parts in the movie (where Doctor Ock’s fusion device was involved) that had unfortunately made no scientific sense. Here are his several observations:

• Doc Ock would have to use deuterium-tritium fusion also, there is no practical alternative. But the nuclear reaction between deuterium and tritium produces a high-energy neutron and a working fusion reactor produces such a high intensity of such neutrons that all nearby life forms would be killed. There is no way that Doc Dock, Spiderman, Mary Jane or anyone else could get close to a fusion plasma and survive, especially without wearing any kind of protective armor. The only practical armor to stop a high intensity source of neutrons is several feet of concrete, not something a person could wear or walk around in. The need to protect against neutrons also explains why you won't be able to have miniature fusion reactors in a car (like in the movie "Back to the Future") or in your house, it is difficult to block high-energy neutral particles, you need a lot of shielding.

• The magnetic bottle that confines fusion plasma is extremely delicate, the smallest change in its properties will cause the bottle to fail and the plasma will be lost almost instantaneously (microseconds). So the parts of the movie showing the plasma wobbling around and even falling into a river were wildly unrealistic.
  
• It takes a lot of complicated big equipment and a lot of energy (tens of megawatts) to boost the temperature of a deuterium-tritium mixture up to 100,000,000 K, when fusion starts to occur. There was no evidence of such equipment in the movie, so how did Doc Ock actually get the plasma started? If the tokamak at Princeton were hooked directly to the power grid, it would knock out the power for most of the northeast part of the US. So what Princeton does is store energy over many days in eight big (15 m diameter) flywheels, and then use the energy stored in the flywheels to start the process of heating the plasma.
  
• The properties of the magnetic bottle change on microsecond time scales. This is way too fast and complicated for Doc Ock to respond to and correct the magnetic fields that confine the plasma, no matter how complicated those arms of his are. The control room of a fusion reactor is actually highly sophisticated, with tens of computers simultaneously changing the magnetic fields of hundreds of magnets that help to confine the plasma, and other computers analyzing data in realtime about the properties of the plasma (as measured by different kinds of laser and radiowave probes). No human being, or group of human beings, could process the data quickly enough nor adjust the hundreds of magnets quickly enough to control the plasma.
  
• The parts of the movie in which all nearby metal objects were being sucked into the plasma make no sense. The magnets that generate the donut-like magnetic field lines that confine the plasma have a special geometry; they are not bar magnets that would attract all iron objects towards them.

It is probably a good thing that the people who made the movie chose to ignore the physics, otherwise the movie would not have been so much fun. It is unfortunate that most viewers don't realize how wrong the science was.

The human race has nearly succeeded with the design of fusion devices. Physicists have created tokamaks that have created plasmas that exceed 300,000,000 K in temperature, kept the plasma confined for over a second, and generate several hundred megawatts of power. But they don't know yet how to create a reactor that can sustain a plasma for hours and that produces gigawatts of energy (the level needed to be practical), they also haven't solved the material science problems of how to reduce the damage to metal and concrete supports caused by the neutrons, they haven't worked out all the details of how to breed tritium fuel by having neutrons bombard liquid lithium that flows through the hole in the magnetic donut. But they have come impressively far, to the point where improvements by factors of three could lead to success.