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I Am Legend's Junk Science: Hollywood Sci-Fi vs. Reality
In the new blockbuster I Am Legend,
virologist Robert Neville (Will Smith) is the sole survivor of a
man-made plague that has wiped out all of humankind—and turned those
who didn't die into creepy, vampire-like mutants. Between a highly
regimented schedule hunting deer in Times Square with his dog, Sam, and
swinging a five-iron from atop a naval cruiser, Neville tries to find a
way to reverse the virus using his own immune blood even as the
Infected are closing in, setting traps and hunting him. But how much of
this sure-to-be blockbuster Hollywood film (based on a famous sci-fi
novel) is fact, and how much is fiction? We consult experts in the
fields of structural engineering, virology and wildlife to determine
what could happen—and what certainly won't.
So what would we see after three years of no activity in New York? Gutters clogged by leaf litter, formerly cleared by the city's maintenance staff, would be a breeding ground for weeds and trees, Weisman says, and streets would flood because, after each rain, the sewers would be clogged with natural matter and plastic bags. Subway tunnels would flood in just two days and, in the absence of firemen, lightning strikes and gas line explosions would cause fires, leaving some buildings charred.
Buildings three years into a post-automotive New York would also look substantially greener. “With no automobile traffic, you'd start seeing moss and lichens growing on them, because there would be no fumes,” Weisman says. “If the heat is off, pipes will burst, and there will be signs of water damage in buildings. You might start seeing some facing breaking off the buildings. If reinforcing bar in any structure starts to rust, the rust expands and you'll see facing popping off.” In the film, buildings are mostly in the background, but you won't see too much of this kind of decay.
Wildlife would most certainly start to creep back into Manhattan, just as the film depicts. “I would not be surprised to see a bunch of deer coming in to graze in Central Park, and there would definitely be wild turkey there,” Weisman says. “The lion would have to come out of a zoo, which means that it would have had to escaped its cage.” Two types of animals you wouldn't see in a post-apocalyptic metropolis are roaches and rats, which both depend on humans to survive. “Roaches aren't going to do real well if there aren't any heated buildings,” Weisman says, and rats will starve without trash to gorge themselves on.
“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.”
The bottom line? This part of the tale is possible, if not entirely likely, Berendsohn says. “As with most good stories, this one requires the audience to suspend its normal mode of disbelief and just get carried along with the tale.”
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 and director of the Laboratory for Immunopathogenesis and Infectious Diseases at Columbia University Medical Center, says the scenario presented in the movie doesn't seem plausible at all. “It sounds pretty far-fetched,” he says. “Viruses don't mutate and become airborne. They typically fall into a couple of different categories—respiratory, STDs and vector-borne like insects, ticks and mosquitoes. They don't change from tick-borne to pneumonic. They just don't do that.”
Equally bizarre, Lipkin says, 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.”
The likelihood of Neville finding a cure from his own blood is slim, too, according to Lipkin. “The notion that by taking a little bit of his blood, he's going to somehow affect this mutation of the people, doesn't make any sense,” he says. “There are some antibodies that might be protective, but they're not going to last forever. And he has to become infected with this in order to develop those antibodies.”
And what about the Infected? “As far as this thing turning people into vampires, and making them look a specific way,” Lipkin says, “that's quite bizarre. This is Hollywood. That's all I can say.”
The cables are run from the shore to the first tower, then to the second tower, and then to the opposite shore; vertical cables hang from the main cable and are attached to the bridge deck at various intervals to support it. In reality, taking out the cables in the middle of the Brooklyn Bridge would cause all the spans to collapse, not just the middle; only the towers would remain standing. And even if the cables were somehow fixed to the top of the towers—which they're not—and the bridge was bombed, “it would pull the tower significantly laterally, and I don't think the tower could stand those sorts of forces,” Bruneau says. “I suppose a writer could imagine a scenario where the cable was welded there, or got jammed or stuck there by debris, but that's science fiction.”
The Urban Jungle
Legend paints post-apocalyptic New York City as an urban jungle being replaced by actual jungle, with plants sprouting up through cracks in the sidewalks and a veritable field of waist-high grass in Times Square. So is this what would really happen if civilization ended? According to Alan Weisman, author of The World Without Us, which analyzes how long man-made structures would survive if humans were to one day vanish from the face of the Earth, the answer is both yes and no. “You'd certainly have a lot of plants growing up through cracks in the sidewalk,” Weisman says. “After three years, you might see some weeds that have made it waist-high in abandoned lots up in the Bronx, but if they're showing a waist-high field of grass in Times Square, that's a bit of a stretch.”So what would we see after three years of no activity in New York? Gutters clogged by leaf litter, formerly cleared by the city's maintenance staff, would be a breeding ground for weeds and trees, Weisman says, and streets would flood because, after each rain, the sewers would be clogged with natural matter and plastic bags. Subway tunnels would flood in just two days and, in the absence of firemen, lightning strikes and gas line explosions would cause fires, leaving some buildings charred.
Buildings three years into a post-automotive New York would also look substantially greener. “With no automobile traffic, you'd start seeing moss and lichens growing on them, because there would be no fumes,” Weisman says. “If the heat is off, pipes will burst, and there will be signs of water damage in buildings. You might start seeing some facing breaking off the buildings. If reinforcing bar in any structure starts to rust, the rust expands and you'll see facing popping off.” In the film, buildings are mostly in the background, but you won't see too much of this kind of decay.
Wildlife would most certainly start to creep back into Manhattan, just as the film depicts. “I would not be surprised to see a bunch of deer coming in to graze in Central Park, and there would definitely be wild turkey there,” Weisman says. “The lion would have to come out of a zoo, which means that it would have had to escaped its cage.” Two types of animals you wouldn't see in a post-apocalyptic metropolis are roaches and rats, which both depend on humans to survive. “Roaches aren't going to do real well if there aren't any heated buildings,” Weisman says, and rats will starve without trash to gorge themselves on.
Power
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, television, DVD player, stereo, home appliances and laboratory during the day and twilight hours—and, by the time we catch up with him in the film, 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.”
The bottom line? This part of the tale is possible, if not entirely likely, Berendsohn says. “As with most good stories, this one requires the audience to suspend its normal mode of disbelief and just get carried along with the tale.”
The Virus
What happens when you manipulate the measles vaccine into a retrovirus, then apply it to cancer patients in a clinical trial? In Legend, you cure cancer. At first. 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 and director of the Laboratory for Immunopathogenesis and Infectious Diseases at Columbia University Medical Center, says the scenario presented in the movie doesn't seem plausible at all. “It sounds pretty far-fetched,” he says. “Viruses don't mutate and become airborne. They typically fall into a couple of different categories—respiratory, STDs and vector-borne like insects, ticks and mosquitoes. They don't change from tick-borne to pneumonic. They just don't do that.”
Equally bizarre, Lipkin says, 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.”
The likelihood of Neville finding a cure from his own blood is slim, too, according to Lipkin. “The notion that by taking a little bit of his blood, he's going to somehow affect this mutation of the people, doesn't make any sense,” he says. “There are some antibodies that might be protective, but they're not going to last forever. And he has to become infected with this in order to develop those antibodies.”
And what about the Infected? “As far as this thing turning people into vampires, and making them look a specific way,” Lipkin says, “that's quite bizarre. This is Hollywood. That's all I can say.”
The Bridge
Perhaps the most iconic image from Legend is the ravaged Brooklyn bridge, its middle span destroyed by a bomb to quarantine New York in one of the film's crucial action sequences. “The middle span is gone up to the towers, and from the towers on, you can still see the suspension cables, the vertical cables and the deck [from the towers to the shores]. That's a bit odd,” says Dr. Michel Bruneau, Director of the Multi-Disciplinary Center for Earthquake Engineering Research and a professor of structural engineering at SUNY Buffalo, because of the way suspension bridges are designed.The cables are run from the shore to the first tower, then to the second tower, and then to the opposite shore; vertical cables hang from the main cable and are attached to the bridge deck at various intervals to support it. In reality, taking out the cables in the middle of the Brooklyn Bridge would cause all the spans to collapse, not just the middle; only the towers would remain standing. And even if the cables were somehow fixed to the top of the towers—which they're not—and the bridge was bombed, “it would pull the tower significantly laterally, and I don't think the tower could stand those sorts of forces,” Bruneau says. “I suppose a writer could imagine a scenario where the cable was welded there, or got jammed or stuck there by debris, but that's science fiction.”