Ever since H.G. Wells’ 1898 classic novel “The War of the Worlds,” science fiction books, movies, and even video games have had fun portraying alien invasion fleets pillaging Earth.

Even the esteemed astrophysicist Stephen Hawking has speculated about space invaders conquering Earth.

But maybe any bellicose extraterrestrials prefer to attack us at the speed of light, literally.

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ANALYSIS: Why Would Aliens Invade?

In an article posted on io9.com, contributor George Dvorsky asked a couple SETI scientists if an alien radio transmission could contain a virus designed to infect our computers and carry out untold mischief. They said that the odds were pretty low, but not impossible.

The phrase “not impossible” is fundamental to any speculation about the future. Any imagined events that obey our present laws of physics are possible, no matter how unlikely.

This is best described in one of Arthur C. Clarke’s three laws of prediction: “When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong.”

That caution aside, speculation about alien cyberwars takes gigantic leaps in logic that push at the boundary of plausibility.

The aliens would somehow have to glean an intimate knowledge of our computer technology. That’s no small trick, unless they can teleport one of our personal computers to their home planet.

What’s more, only civilizations orbiting stars within 90 light-years of Earth would even suspect we had a SETI program. That’s because it has been less than a century since artificially produced electromagnetic radiation has been leaking off into space from our society.

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If we assume that one of these hypothetical nearby civilizations is bent on pulling off an interstellar cyber-terror attack, it could take dozens of years for their signal to reach our radio telescopes at the speed of light. By the time the transmission arrived our computer technology would have substantially evolved from what it is today.

The barriers of time and space ensure a cosmic firewall from cyberattacks.

That is unless the extraterrestrials developed some sort of quantum faster-that-light eavesdropping capability that would allow for their malware to be instantaneously adjusted to blow through the latest Microsoft security update.

More fundamentally, why would an advanced civilization waste the time and resources to go to the effort of undermining our comparatively primitive technology?

All I can imagine — and it would make a fun science fiction story — is if an alien computer virus took over an automated military weapons factory (as was done by hackers in the 1983 film “Brainstorm”) and reprogrammed the assembly robots to crank out an army of killer androids that looked like the The Terminator.

HOWSTUFFWORKS: What Might Aliens Be Like?

Equally implausible, as dramatized in Carl Sagan’s 1985 novel “Contact,” is the worry that aliens send us blueprints for constructing a high-tech Trojan Horse. “The transport theory is only one hypothesis, … and in my view a rather naive one,” warns the U.S. President’s nation security adviser, “We build it [the alien machine] and out pours the entire Vegan [from the star Vega] army.”

Just imagine if we had some sort of time machine where we could communicate with the ancient Romans and teleport to them blueprints for making a Predator drone or even a machine gun.

Time travel paradoxes aside, it would be utterly impossible for the Romans to fabricate such devices. And, they are only separated from us by 2,000 years — not 10,000, 100,000, or 1 million years. This is more likely the evolutionary gap between us and science savvy extraterrestrials, given the age of our galaxy.

So if you’re using SETI@Home or Astropulse to hunt for E.T. don’t remove it from your computer. The odds of alien viruses getting into your hard drive are as close to impossible as I can imagine.

Image credit: Top: Image courtesy of NRAO/AUI and NRAO. Bottom: SETI Institute