In February, 1999, physicists from The Rowland Institute for Science in Cambridge, Massachusetts, achieved a phenomenal and path-breaking scientific feat. They managed to reduce the speed of light. This reduction in speed was not minute. In fact, it was extraordinary. The physicists reduced the speed of light from 186,000 miles per second to a modest 38 miles per hour.1 That effectively means slowing down something that could circle around the globe roughly 7 times / second to the speed of your average vehicle. Courtesy of this experiment, light could now physically be seen moving from point A to point B, much like a ball being thrown or a dart being fired from one point to another. Let’s decode how this feat was achieved.
Slowing light through sodium atoms
The light was passed through a cluster of tightly knit sodium atoms, under low temperatures and a vacuum. The presence of the vacuum along with sub-freezing temperatures, caused the already closely knit atoms to fuse together. This further slowed down the speed of light, to finally clocking it at just 38 MPH.
Race between 2 beams of light
In another experiment, two beams of light were independently and simultaneously released. One beam of light passed through a special mask, while the other did not. The beam of light that passed through the mask reached the finish line second, and lost the meter long race.The mask altered the photon’s trajectory, slowing it down.2
Slowing light by twisting
Researchers from the University of Philippines slowed down the speed of light by rotating the light beam. The degree at which the light beam was rotating is measured through a metric called OAM (orbital angular momentum). Researchers concluded that change in the OAM of a spectrum of light had a direct effect on its speed.3
Photonic silicon waveguide IBM chip
In 2005, IBM created a computer chip that slowed down the speed of light by navigating it through set passages within their chip. The light was slowed down to 1/300th of its original speed.3 IBM claimed that by reducing the speed at which light travels within its chip, it would increasing the energy efficiency of their microprocessor.