Stephen Hawking may have passed away, but his views on science and physics will be studied for decades to come. Arguably one of the most brilliant physicists in our recent history, Hawking taught us a great deal about cosmology and the unseen world around us. But what were his views on time travel?
First, let’s review time travel in an incredibly simplistic way. Thanks to Einstein, we know that time dilation is real thing. The faster someone travels and the closer they get to light speed, the slower time moves for them, while time continues to move at the same pace for people on Earth. Therefore, theoretically, someone traveling at light speed could come back to Earth and find that very little time had passed for them, compared to everyone else on the planet experiencing a hundred years or more. Of course, getting to light speed is a different matter entirely, requiring increasing energy the closer we get to c, until getting there becomes nearly impossible (and surpassing it requires infinite energy.) Light has found a workaround because photons (particles of light) are massless (and also function as waves.) But mankind has yet to find its own workaround. Meanwhile, traveling back in time is a different matter entirely, and scientists argue about whether it is theoretically possible or not. Here’s one argument for retrocausality, made in July 2017. (But here’s another thought experiment: Traveling back in time might come with a huge cost. Have you ever heard of “The Great Filter“? It’s the idea that there’s some catastrophic reason we’ve never seen aliens. One reason might be that the moment they create FTL, they also create time travel and somehow annihilate themselves. Not likely, but you never know.)
Now that we’ve gotten this very simplistic explanation out of the way, what did Hawking believe about time travel? Did he believe it was possible? It turns out, he had a lot to say. He believed some types of time travel were possible, but not all. Read on for a “brief history” of his views on the subject.
Traveling Back in Time Would Require Wormholes, But Hawking Believed Radiation Feedback Would Stop Their Creation
GettyPhysicist Stephen Hawking onstage during the 2010 World Science Festival Opening Night.
In 2010, he wrote an article published in Daily Mail about what would be needed to build a time machine. Everything, even time itself, has wrinkles and voids in it if you look close enough — down to the smallest of scales — he wrote. There are tiny tunnels in the quantum world that constantly form, disappear, and reform, linking separate places and even times. But they are far too small for a human to pass through. However, he wrote, it might be theoretically possible one day to capture a wormhole and enlarge it so a spaceship could pass through. “I’m not saying it can be done, but if it could be, it would be a truly remarkable device. One end could be here …read more