Controlling the speed of light up to 30 times faster and also backwards

Nature always turns out to be so much stranger than anything we could have ever imagined:

"Abouraddy and study co-author Esat Kondakci demonstrated they could speed a pulse of light up to 30 times the speed of light, slow it down to half the speed of light, and also make the pulse travel backward."

Researchers develop way to control speed of light, send it backward

Crazy stuff.

a reply to: dfnj2015

Please excuse me for finding this a little hard to believe.

a reply to: dfnj2015

How am I to understand this

Abouraddy and study co-author Esat Kondakci demonstrated they could speed a pulse of light up to 30 times the speed of light

Do they mean 30 times faster hen he speed of light ?

If one can control light to the point of reducing, increasing, or reversing its speed.... wouldn't you think they had the ability to create stationary balls of light, or controlled balls of light? Maybe the lights seen around the world, hovering above cities, is nothing more than this scientific application?

This didn't happen. Think about it. How would they measure the speed when the fastest speed of mass-less particles is c?

Maybe it's a belated April Fool's posting.

Something doesn't seem right here. Wouldn't this be one of the greatest breakthroughs in the history of science? I mean 30 times the speed of light? That seems pretty incredible.

Okay, c0 is the max velocity in vacuum, and these scientists claim they did it in "open space", but meant in my opinion not a vacuum.

They cannot go faster than c0.

They can go faster than c in a medium, see tcherenkov radiation. But then it seems that this article is missing several clues.

a reply to: Maverick7

This didn't happen. Think about it. How would they measure the speed when the fastest speed of mass-less particles is c? Maybe it's a belated April Fool's posting.

There would be ways to measure it if they indeed did change the speed of the photons so dramaticly.

in 1849, the speed of light was first measured by measuring the time it took to go 8km, hit a mirror, and return. Its trip speed was measured using a rotating cog with an aperature, whose speed of rotation was changed until it was in sync capturing the light once leaving, and once returning.

A similar setup, or hundreds of more sophisticated ways could be used here, if this is a true event.

a reply to: dfnj2015

Link to the actual paper published in February if anyone's interested, instead of the clickbait garbage in the op.

www.nature.com...

a reply to: chadderson

kylo ren can do it

originally posted by: chadderson
If one can control light to the point of reducing, increasing, or reversing its speed.... wouldn't you think they had the ability to create stationary balls of light, or controlled balls of light? Maybe the lights seen around the world, hovering above cities, is nothing more than this scientific application?

It's not light if it's stationary.


Think about it.

If you stop a photon, it will never hit your eyes- so you can't see it.


If I had to guess, this is all calibration errors.
Or rounding in measurements.

originally posted by: Spacespider
a reply to: dfnj2015

How am I to understand this

Abouraddy and study co-author Esat Kondakci demonstrated they could speed a pulse of light up to 30 times the speed of light

Do they mean 30 times faster hen he speed of light ?

Yeah, 30 times. I'm now writing for physics.org.

originally posted by: dug88
a reply to: dfnj2015

Link to the actual paper published in February if anyone's interested, instead of the clickbait garbage in the op.

www.nature.com...

#&$*#&$*@*!@*!

originally posted by: dug88
a reply to: dfnj2015

Link to the actual paper published in February if anyone's interested, instead of the clickbait garbage in the op.

www.nature.com...

From your click bait, "from 30c in the forward direction to −4c" .

a reply to: dfnj2015

You have to be careful with such articles.

What they mean is the so called group velocity, which can indeed exceed the speed of light. But the waves composing the signal are still traveling at c. So the group velocity in that case has no physical meaning.

Imagine you would have a long row of lights. Each light would be lighted a bit later then the one before it. This delay would be preset for each light. So you'll essentially get a moving light. You can now reduce the delay to a point where this "moving" light will exceed speed of light.

a reply to: moebius
The original science article uses proper language but the science writer for the OP's source completely mangled and misrepresented the science terminology, but yes as you say it's group velocity.

There is no violation of relativity for a group velocity, or phase velocity, or certain other things to exceed c (the speed of light), as explained in the Faster than Light Wikipedia article. Here is part of what it says about group velocities going faster than the speed of light:

The group velocity of a wave may also exceed c in some circumstances.[14][15] In such cases, which typically at the same time involve rapid attenuation of the intensity, the maximum of the envelope of a pulse may travel with a velocity above c. However, even this situation does not imply the propagation of signals with a velocity above c,[16] even though one may be tempted to associate pulse maxima with signals. The latter association has been shown to be misleading, because the information on the arrival of a pulse can be obtained before the pulse maximum arrives.

Consistent with that explanation the authors do not claim any propagation faster than the speed of light, just a group velocity faster than light which is not a new thing.

Can you imagine the LiFi speeds you could get with a system that works like this?

This has bad-ass data transmission tech written all over it.

originally posted by: Spacespider
a reply to: dfnj2015

How am I to understand this

Abouraddy and study co-author Esat Kondakci demonstrated they could speed a pulse of light up to 30 times the speed of light

Do they mean 30 times faster hen he speed of light ?

There is a difference between the propagation speed of a packet of light and the speed of the constant 'c' which is often called the speed of light.

This article describes the various ways the propagation speed can be manipulated.