Scientists Have Slowed Light Down To An Embarrassing 38 Miles Per Hour
Scientists Have Slowed Light Down To An Embarrassing 38 Miles Per Hour
You could overtake the fastest thing in the universe on a pushbike.
James Felton
Senior Staff Writer
Edited
by
Maddy Chapman
Abstract image of light.
Not so fast now, are you, light?
The speed of light in a vacuum is the absolute speed limit of the universe. Nothing will go faster than 299,792 kilometers per second (186,000 miles per second), according to Einstein's work, as it would require an infinite amount of energy to do so.
However, that doesn't mean that light can't be beaten in terms of speed under the right set of circumstances. In water, for example, light is slowed down to 225,000 kilometers per second (139,800 miles per second), which is still pretty zippy, but can be beaten by particles (e.g. in a nuclear reactor) and result in Cherenkov light.
But 225,000 kilometers per second is far from the slowest that light has ever traveled. In 1998, scientists were able to slow it to just 17 meters per second, or an embarrassing 61.2 kilometers (38 miles) per hour.
Slowing light was not the ultimate aim of the experiment. The team were keen to study Bose-Einstein Condensate (BEC), a state of matter first hypothesized by Albert Einstein based on the work of theoretical physicist Satyendra Nath Bose. When a gas of bosons – subatomic force-carrying particles that have integer spin – are cooled to temperatures approaching absolute zero, they form a single quantum object, often compared to it acting as a single atom.
"The wave function of a BEC corresponds to the ground state of a macroscopic quantum object," one paper explains. "In other words, a collection of atoms in a BEC behaves as a single quantum entity."
In this strange new state of matter, first created in the real world in 1995, you get a macroscopic look at quantum behavior.
More:
https://www.iflscience.com/scientists-have-slowed-light-down-to-an-embarrassing-38-miles-per-hour-75894
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