There are so many places in the universe to explore, but with current rocket technology, it would take millions of years to reach some of the most interesting planets, moons and stars. Unless we hitch a ride on a beam of light.

Physicist Stephen Hawking is one of the people trying to turn that science-fiction concept into reality and he stumped for it while speaking at a festival earlier this week. During a talk at the science and art festival Starmus in Norway, where Hawking was part of a group of speakers that included Apollo 11 astronaut Buzz Aldrin and astrophysicist Neil deGrasse Tyson, he called on humans to leave Earth and explore areas beyond our solar system in a search for a habitable replacement we can colonize. But that would require some new spaceships.

He specifically pointed to Proxima Centauri b, a planet that could be a good candidate but is 4.5 light years from Earth — more than 26 trillion miles away. To reach it and sniff it out as a potential new home for Earthlings would take millions of years if we used rocket propulsion technology that exists today. But Live Science reported he offered alternative transportation: a light beam.

Read: The Coolest Habitable Exoplanets

The method of space travel theoretically works with a ship first being launched into space, after which a laser light, or an array of laser lights, would be beamed from a location on Earth onto the back end of a “lightsail” on the ship to move it forward.

Hawking is part of a project called Breakthrough Starshot that is looking to create the first of such transport systems — but with a small and lightweight craft rather than the kind of large one that would be needed to ferry a human population and all the supplies needed to another planet. The goal is to get the spacecraft up to 100 million mph.

“To go faster would require a much higher exhaust speed than chemical rockets can provide — that of light itself,” Hawking said. “A powerful beam of light from the rear could drive the spaceship forward” and bring it up to speed, perhaps reaching a tenth or even a fifth of light’s velocity.

That is many thousands of times faster than the maximum speed humans currently can achieve.

Although it would take quite a bit to advance space travel that much, going any faster would require technology beyond current imagination.

Read: The Aliens Out There Are Probably Swimming, Not Walking

Why is Hawking pushing for this technology? The physicist has made it clear he thinks life on Earth is doomed. During his Starmus talk, he said humans will have to colonize Mars or another location within the next 100 years if we want to survive extinction. That wasn’t the first time he has made that claim. Hawking has listed climate change, nuclear war and disease as possible calamities that would kill off the human species on Earth.

“Shouldn’t we be content to be cosmic sloths, enjoying the universe from the comfort of Earth? The answer is, no,” Hawking said at Starmus. “The Earth is under threat from so many areas that it is difficult for me to be positive.”

The moon and Mars are not viable options for long-term human living because in addition to them being barren and devoid of water, the lack of atmosphere on those worlds would expose people to intense radiation. Even the head of the European Space Agency says living on Mars or the moon would be an awful idea.

“Human colonization on other planets is no longer science fiction. It can be science fact,” he said. “If humanity is to continue for another million years, our future lies in boldly going where no one else has gone before.”