Danish Physicist Lene Hau was Able to Slow Down the Speed of Light to 38 mph and was Eventually Able to Manipulate it


The speed of light is a fundamental scientific constant that governs many aspects of physics. The constant and finite speed of light is 186,000 miles per second. But did you know that you could change the speed of light?

In 1999, Danish physicist Lene Hau accomplished the first slowing of light to 38 mph. Later on, she was able to fully stop, control, and move it.

Lene Hau, who is she?

On November 13, 1959, physicist Lene Vestergaard Hau was born in Vejle, Denmark. She is most known for her work slowing and stopping light. She earned a PhD, a master's degree in physics, and a bachelor's degree in mathematics from Aarhus University in Denmark.

Research on the Speed of Light by Lene Hau

In 1999, Hau achieved cycling at the speed of light after years of practise.

She achieved this amazing feat by pedalling at a modest 60 kilometres per hour as opposed to cycling faster. She did something much more amazing: she stopped the light in its tracks.

The speed of light is 186,000 miles per second. Hau was aware of this but never intended to break the record for light-speed slow-speed travel. Shortly after arriving, she began a new research project: searching for the Bose-Einstein Condensate, a brand-new state of matter.

A few millionths of a degree above absolute zero causes atoms to lose their identity and fuse because they are so sensitive to temperature.

The Bose-Einstein Condensate is named after the two physicists whose research first predicted its existence in 1924 and can behave like a single superatom at low enough temperatures.

"I was incredibly interested to learn more about this novel state of matter. We were quite joyful. We were successful." Scientist Lene Vestergaard Hau

In June 1997, when the atoms had been effectively cooled by Hau and her colleagues, the Bose-Einstein Condensate finally formed.

Hau and her coworkers began looking for applications for the condensate after producing it. They found that by precisely controlling the condensate with laser beams, they could make light pass through the previously opaque condensate. They came to the conclusion that the manipulated condensate was the only material known could delay light as effectively as it could.

A 0.2 millimeter-long, cigar-shaped condensate was suspended inside a vacuum chamber using an electromagnet. They fired a pulse of laser light along the cigar's long axis after illuminating it from the side with a properly regulated laser beam.

The pulse slowed and compressed as soon as it came into contact with the changed condensate. Hau worked all night in the lab for a year perfecting her test method for slowing light. In March 1998, she finally noticed that the light was becoming less intense.

I remarked, "Wow, you must be the first person to notice light moving this slowly. Scientist Lene Vestergaard Hau

When she boarded a trip to Copenhagen that summer, she realised she was moving faster than her light beams. That fall, once she had succeeded in getting light to move at a bicycle's speed, she published her findings.

This year, her team made strides in their research by completely obliterating all light inside a Bose-Einstein Condensate. The light pulse was entirely compressed and confined in the condensate, and the coupling laser was turned off immediately. After this alteration, the light became imprisoned inside. They turned the coupling laser back on and the initial light pulse came out the other end.

Reference:  Physics Today 

Post a Comment


  1. I'm most definitely not a physicist, but I do have a question about this. I find it both staggering and amazing that Lene Hau was able to control the speed of light...especially down to a speed that virtually everyone can comprehend.

    However, how can this be used to advance other studies into physics? What will be gained from this discovery? Will this be able to help other physicists better understand the nature of photons, and then (hopefully) develop something new because of this new understanding?