Physicists might just have found a way to bring light to a standstill and then start it up again

The speed of light in the vacuum is a universal physical constant as long as nothing gets in its way. But, scientists have now theorised a way to not only change the value of the speed of light but also to bring moving light to a complete halt.

The development can open up several avenues for technologies that rely on light for the storing and passing of information, including quantum computing.

This method to slow down the light has been put forward by physicists Tamar Goldzak and Nimrod Moiseyev of the Israel Institute of Technology, along with Alexei A. Mailybaev of the Instituto de Matemática Pura e Aplicada (IMPA) in Rio de Janeir. The group of scientists have published a paper on stopping light at exceptional points in Physical Review Letters, notes Phys.org (PO).

The scientists argue that two separate beams of light can be tuned in such a way that they would merge at an "exceptional point", which will bring them to a halt. According to a Science Alert (SA) report, an exceptional point is a mathematical term that is used to describe how different waves' features match one another at a given coordinate.

The report also mentions that the very existence of such points was theoretical until a recent experiment proved that it was practically possible to create such points by confining microwaves in a narrow grid.

Apart from wavelength and frequency, light also has other features which form repeating patterns as photons travel through space. Now, such repeating patterns can be tweaked by making use of waveguides so that two light waves can merge in the same space, notes the SA report. The point where light coalesces is called the exceptional point.

According to the SA report, the light waves can be made to meet and freeze, or speed up and resume their journey by tuning the set-up in such a way that the waves gain or lose energy. It is to be noted that this light stopping property is still in the theoretical stage, a light stopping and starting device is yet to be built.

The PO report mentions that the most important feature of this theory is that the exceptional points can be adjusted to work with any frequency of light simply by tuning the gain/loss parameters.

Interestingly, it is not only light but also other kinds of waves, including sound, which can be manipulated in this manner, the report added.