Stephen Hawking recently began using a speech synthesizer system that uses artificial intelligence to predict words he might use.

The eminent British physicist Stephen Hawking warns that the development of intelligent machines could pose a major threat to humanity.

"The development of full artificial intelligence (AI) could spell the end of the human race," Hawking told the BBC.

The famed scientist's warnings about AI came in response to a question about his new voice system. Hawking has a form of the progressive neurological disease called amyotrophic lateral sclerosis (ALS or Lou Gehrig's disease), and uses a voice synthesizer to communicate. Recently, he has been using a new system that employs artificial intelligence. Developed in part by the British company Swiftkey, the new system learns how Hawking thinks and suggests words he might want to use next, according to the BBC. [Super-Intelligent Machines: 7 Robotic Futures]

Humanity's biggest threat?

Fears about developing intelligent machines go back centuries. More recent pop culture is rife with depictions of machines taking over, from the computer HAL in Stanley Kubrick's "2001: A Space Odyssey" to Arnold Schwarzenegger's character in "The Terminator" films.

Inventor and futurist Ray Kurzweil, director of engineering at Google, refers to the point in time when machine intelligence surpasses human intelligence as "the singularity," which he predicts could come as early as 2045. Other experts say such a day is a long way off.

It's not the first time Hawking has warned about the potential dangers of artificial intelligence. In April, Hawking penned an op-ed for The Huffington Post with well-known physicists Max Tegmark and Frank Wilczek of MIT, and computer scientist Stuart Russell of the University of California, Berkeley, forecasting that the creation of AI will be "the biggest event in human history." Unfortunately, it may also be the last, the scientists wrote.

And they're not alone — billionaire entrepreneur Elon Musk called artificial intelligence "our biggest existential threat." The CEO of the spaceflight company SpaceX and the electric car company Tesla Motors told an audience at MIT that humanity needs to be "very careful" with AI, and he called for national and international oversight of the field.

It wasn't the first time Musk warned about AI's dangers. In August, he tweeted, "We need to be super careful with AI. Potentially more dangerous than nukes." In March, Musk, Facebook founder Mark Zuckerberg and actor Ashton Kutcher jointly invested $40 million in an AI companythat is working to create an artificial brain.

Overblown fears

But other experts disagree that AI will spell doom for humanity. Charlie Ortiz, head of AI at the Burlington, Massachusetts-based software company Nuance Communications, said the concerns are "way overblown."

"I don't see any reason to think that as machines become more intelligent … which is not going to happen tomorrow — they would want to destroy us or do harm," Ortiz told Live Science.

Fears about AI arebased on the premise that as species become more intelligent, they have a tendency to be more controlling and more violent, Ortiz said. "I'd like to think the opposite. As we become more intelligent, as a race we become kinder and more peaceful and treat people better," he said.

Ortiz said the development of super-intelligent machines is still an important issue, but he doesn't think it's going to happen in the near future. "Lots of work needs to be done before computers are anywhere near that level," he said.

Follow Tanya Lewis on Twitter. Follow us @livescience, Facebook & Google+. Original article on Live Science.