Any source of power, including hydroelectric and nuclear, would have ceased long before the three-year timeline of I Am Legend. So, Neville makes do using three small gasoline-powered generators. They allow him to power his lights, TV, stereo and laboratory during the day and twilight hours and, have done so for over 1000 days. “Three small generators can power a house and everything in it,” says PM’s senior home editor Roy Berendsohn. “If these are very fuel efficient generators, and he’s being conservative with their use, he’ll use maybe 5 to 9 gallons of gasoline a day.” That translates to a lot of fuel–5000 to 9000 gallons over 1000 days. Neville does have access to the below-ground tanks of the city’s gas stations, which, according to Berendsohn, could have between 3000 to 10,000 gallons each. Considering that New York has about 100 gas stations, Neville would have enough fuel to last him a long time.
Still, Berendsohn says, “chances are he’d have a difficult time with the generators as the years roll slowly by. The gas would not be fresh after nearly three years in the ground, and the generators would need service, such as spark plugs and so forth.” So, this part of the tale is plausible, if not entirely likely, Berendsohn says.
So the state of the city is relatively accurate, what about the virus and what it does?
In the movie they manipulated the measles vaccine into a retrovirus and then applied it to patients in a clinical trial. At first it cured cancer. Then, the patients begin to get sick. Most of them bleed out, but those who don’t become hairless, transparent, vampire-like mutants who are allergic to sunlight and crave blood. They spread the disease by biting others. When the virus mutates and goes airborne, it spreads rapidly, killing everyone on Earth except for those who are immune–and slowly, even they are picked off by the vampires, until only one man is left. Though the film’s press release claims “the possibility of a retrovirus spreading out of control is no longer just the fodder for science fiction stories,” Dr. W. Ian Lipkin, one of the world’s top virologists says the scenario presented in the movie doesn’t seem plausible at all. Viruses don’t just mutate and become airborne. They usually fall into a category like vector borne, respiratory, or STD. They don’t just change from tick-borne to pneumonic. Equally bizarre according to Lipkin is Neville’s immunity. “There are people who are resistant to retroviruses because they have mutations in receptors, but that’s a mutation that people have from the get-go,” he explains. “If someone had been exposed to a related virus and was immune to it, then they would carry that immunity, and that would be something that would occur over the course of their lifespan. But how this guy would have come into contact with such a virus is unclear, and certainly wouldn’t be explained in that way.” Lipkin also debunks the notion of him being able to create a cure from his own blood. It isn’t really possible for Neville to take a small amount of his blood and it make a difference in these people’s mutation. There are antibodies that could be protective, but they wouldn’t last forever. Also, Neville would have had to be infected to even develop the antibodies. Lipkin also thinks that the infected are quite bizarre as well. Just because you are infected with a virus you won’t become a vampire. They wouldn’t cause such a drastic change.