Now, Light Can Travel Faster Than The Speed of Light!
By on August 12th, 2011

Now light would lose to light, if it were to race against itself. Researchers have now made light propagate through special media at speeds faster than the conventional speed of light (a mind-boggling 299,792,458 m/s). However, Einstein and his many fans need not worry; this faster-than-light propagation doesn’t violate relativity, which states that the speed of light is the fastest speed possible.

Building Packets of Waves

The secret to such a feat is the building up of wave-packets. Wave-packets are exactly what their name suggests packets of waves. Interference of waves is the key phenomenon.

Waves have the unique property to interfere, whether it be constructively or destructively. When two waves overlap, peak to peak, the overlap or interference is maximal. This is called constructive interference. When the waves overlap, such that peak and trough coincide, they cancel each other’s contribution out, giving destructive interference.

Interference pattern formed by the interference of light from two sources. Notice the dark ridges, where light interferes destructively. The bright regions is due to constructive interference

By selecting a large number of waves (theoretically, an infinite number), differing from each other by fraction of their wavelengths, a wave-packet can be built, such that it has a central peak, smoothly falling off on either sides. The waves interfere constructively near the peak and destructively further away from it. Thus, we arrive at an important conclusion: The constituent waves determine the position and magnitude of the peak of the wave-packet, through their mutual interference.

Wave Packet formation.

If we could find a material, which would selectively allow only certain wavelengths to go through, a wave-packet can be suddenly deformed when it enters a medium. Also, we could shift the location of the peak.

Shifting peaks and moving fast

Enter Vitaliy Lomakin of the University of California, San Diego and his colleagues at the Public University of Navarre in Pamplona, Spain. They used Teflon as the propagating medium. Microwave radiation was made to pass through a copper disc sandwiched between two Teflon discs. It was noticed that the wave jumps forward, emerging from the back Teflon plate, before it enters the metal plate. The team reported sending 10% of the light 10 picoseconds earlier than usual.

Einstein still stands tall

Physicists interpret the postulate of relativity to mean that information cannot be transferred faster than light. Here, no useful information can be transferred for that the entire wave-packet has to be transferred, not some part of it. The wave-packet is highly distorted, and also markedly reduced. Causality is not violated.

Einstein still stands, even though light can now travel faster than itself. The findings will soon be published in the prestigious Physical Review Letters.

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Author: Debjyoti Bardhan Google Profile for Debjyoti Bardhan
Is a science geek, currently pursuing some sort of a degree (called a PhD) in Physics at TIFR, Mumbai. An enthusiastic but useless amateur photographer, his most favourite activity is simply lazing around. He is interested in all things interesting and scientific.

Debjyoti Bardhan has written and can be contacted at debjyoti@techie-buzz.com.
  • Yehoshua Ghitis

    By speeding up the speed of light, we will be able to go faster than the current speed and travel in time! Brilliant! /slapped

    • Debsuvra Ghosh

      It’s about the phase velocity of a light quantum in the wave packet, phase velocity can break the so called lightspeed barrier but the group velocity of the packet remains lower or equal to the speed of light. This has nothing to do with travelling in time and breaking time-space continuum.

      • Debjyoti Bardhan

        That is the exact reason why information cannot be transfered. But, remember that for light the phase velocity is the same as the group velocity equal to the velocity of light.

  • http://2buntu.com Roland Taylor

    I think this has been known for some time now. There was a guy in Israel who said light could go 300x faster – essentially reaching the destination before making the journey.

    • Yehoshua Ghitis

      Well then, that is something I really was not aware of, very interesting. Now that I have your attention, why would it be that no one ever comments here? The articles in Techie-Buzz are very interesting but I have never seen any readers give their own opinions.

      • Debjyoti Bardhan

        Thanks for the appreciation, on behalf of the entire techie-buzz team.

  • Debjyoti Bardhan

    Here’s an article pointing out to the 300x speed of light thingy. Enjoy. http://www.guardian.co.uk/science/2000/jul/20/technology2

  • http://www.unlimitedtips.com Ayush Chand

    All your articles are cool! Good physics man!

  • http://chaoticexotics.biz James Ph. Kotsybar

    OFF THE SCALE
    — James Ph. Kotsybar

    The young lady known only as Bright,
    who could travel at speeds fast as light,
    said. “Though I’m seldom late,
    I’m concerned that my weight
    goes to infinite mass, though I’m sleight.”

 
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