Would you believe that the speed of light can be slowed to the mere crawl of a moped at full throttle, roughly 38 mph? Most people would probably think that I have been out the back inhaling an illegal substance that inhibits my thought process with a statement like that, but it’s true, and can be done. But the concept itself really does mess with your head, because nothing can travel at the speed of light, except light. And to slow it down to only 38 MPH means that just about everyone has at some stage gone faster that that slowed down speed of light. So how was the speed of light slowed down to the speed of a pushbike, when Einstein’s theory of special relativity says that the speed is constant?
If I were to ask you what the speed of light is, would you say only 38 mph? No, I didn’t think so. Unless you’re into all things physice, you’ll probably head over to Google for the answer, which is 299,792,458 m / s. Or in more easily understood language, 670,616,629 mph (1,079,252,848.8 km/h). So really freaking fast. Another thing, unlike the speed limits placed on public roads that can be broken, the speed of light is the limit. Nothing can go faster than it. So on to the experiment.
This is a really cool experiment that requires some pretty specialized equipment, not to mention something that has to be made artificially. Essentially the coldest thing in the universe, Bose-Einstein Condensate, which we have already discovered is right here on planet Earth.
To get the speed of light slowed down to the steady pace of grandmother on the freeway, the scientists fired beams of light into the Bose-Einstein Condensate. When the beams entered it, they not only slowed down significantly, but also compressed. This is because as the first parts of the light entered the condensate they slowed down, while the parts that weren’t yet there were travelling at the thrilling speed of 299,792,458 m / s, quickly squashing up behind the slow particles ahead of them, just like that annoying older driver on the freeway. Once all of the light beam had fully entered the frigid artificial cloud, it traveled along its very small segment of condensate at only 38 mph.
But what about Einstein’s theory of special relativity? Well, it’s still correct. The theory puts an upper limit on the speed of light, but not a lower limit on it. It would be scientifically possible to slow it down even more, even if ever so briefly.
Watch this cool video below which demonstrates how they slowed the speed of light to only 38 mph.