Physicists beat the speed of light using pulses inside a hot plasma

(ORDO NEWS) — Most of us grow up familiar with the current law that limits the speed at which information travels through empty space: the speed of light, which reaches 300,000 kilometers (186,000 miles) per second.

While photons on their own are unlikely to ever break this speed limit, there are features of light that don’t follow the same rules.

Controlling them won’t speed up our ability to travel to the stars, but they could help us clear the way for an entirely new class of laser technology.

Physicists from the USA have shown that under certain conditions, waves consisting of groups of photons can travel faster than light.

Researchers have been actively and rapidly playing with speed limiting light pulses for some time, speeding up and even slowing them down to a virtual stop using various materials such as cold atomic gases, refractive crystals and optical fibers.

But what’s impressive is that last year, researchers at the Lawrence Livermore National Laboratory in California and the University of Rochester in New York manipulated this in a hot swarm of charged particles, fine-tuning the speed of light waves in a plasma from about one-tenth the normal speed of light in a vacuum to over than 30% faster.

It is both more and less impressive than it sounds.

To break the hearts of those who hope it will take us to Proxima Centauri and back for tea, this FTL travel is completely in line with the laws of physics. Sorry.

The speed of a photon is fixed by an interweaving of electric and magnetic fields, called electromagnetism. There is no escape from this, but the pulses of photons with narrow frequencies also push each other in such a way that they create regular waves.

The rhythmic rise and fall of entire groups of light waves travels through the material at a speed described as the group velocity. , and it is this “wave of waves” that can be tuned to slow down or speed up depending on the electromagnetic conditions of its environment.

By detaching electrons from a stream of hydrogen and helium ions from a laser, the researchers were able to change the group velocity of light pulses passed through them by a second light source, slowing down or optimizing them, adjusting the ratio of gases and forcing the characteristics of the pulse to change shape.

The overall effect was due to the refraction of the plasma fields and the polarized light of the primary laser used to remove them. The individual light waves were still racing at their normal pace, even though their collective dance seemed to have sped up.

From a theoretical point of view, the experiment helps to concretize plasma physics and imposes new restrictions on the accuracy of measurements. current models.

Practically speaking, this is good news for advanced technologies waiting in the wings to find clues on how to get around the obstacles preventing their implementation into reality.

Lasers will be the big winners here, especially the insanely powerful variety. Old school lasers are based on solid-state optical materials, which tend to get damaged when the energy is increased.

Using plasma streams to amplify or modify light characteristics could get around this problem, but to get the most out of it, we really need to model their electromagnetic characteristics.

Lawrence Livermore National Laboratory is not accidentally striving for this. understand the optical nature of plasma while being home to some of the most impressive laser technology in the world.

Increasingly powerful lasers are what we need for a range of applications, from increasing the power of particle accelerators to improving cleanliness. thermonuclear fusion technologies.

It may not help us move faster in space, but these discoveries will bring us closer to the future we all dream of.

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