Everyone is taught in school that nothing travels faster than light. But actually, some things do.
The phenomenon, known as the Cherenkov effect, was first observed by Soviet scientists in 1934, but has been familiar only to those who study things like nuclear reactors and cosmic rays.
Now, a team of researchers from the United States, Israel, Croatia and Singapore has found that one can potentially use this principle to make computers one million times faster than they are now.
Led by researchers at the Massachusetts Institute of Technology (MIT), the team demonstrated that it is possible to exploit the Cherenkov effect to efficiently convert electrical energy into light energy.
The light energy could, with development of additional technology in the future, be used to process data up to a million times faster than the traditional electrons bouncing around in today's computers.
At the moment, the researchers have only some theoretical calculations to show for their efforts, but the findings have already been published in the journal Nature Communications in June this year.
AT THE TECHNOLOGICAL FRONTIER
It goes to show how close to the frontier we are... This is a very fundamental effect but nobody has demonstrated it yet.
DR WONG LIANG JIE, from the Singapore Institute of Manufacturing Technology, on the possibility of exploiting the Cherenkov effect to efficiently convert electrical energy into light energy.
"It goes to show how close to the frontier we are... This is a very fundamental effect but nobody has demonstrated it yet," said Dr Wong Liang Jie, 32, from the Singapore Institute of Manufacturing Technology (SIMTech), who did the calculations.
They were also hampered by real-world constraints. Lead author Ido Kaminer, a post-doctoral fellow at MIT's department of physics, said: "The 12-hour time difference is very challenging. It means our (online) meetings typically occur around 10pm for one side and 10am for the other."
But it has been "a very fruitful collaboration", as SIMTech contributed unique numerical simulation tools and other necessary expertise, Dr Kaminer added.
Traditionally, for their data-processing tasks, computers depend on transistors that manipulate electrons. The size of transistors has been halving roughly every two years since the 1960s, allowing ever greater computing power to be packed into a microchip.
However, there is a limit, as the tiny and densely packed transistors are prone to overheating and data errors.
One way of overcoming this barrier may be to use light instead of electrons to process the data. Light generates less heat, and can process data much more rapidly.
This is because light can be modulated to store a sequence of ones and zeroes - the computer's internal language - at a much higher frequency than electrons, said Dr Wong.
While electrons can be modulated at a frequency of a few gigahertz in desktop processors today, light can potentially be modulated a million times faster.
But first, one needs to convert electrical energy to light in an efficient way. This is where the Cherenkov effect comes to the rescue.
Nothing can travel faster than light in a vacuum, but it is a different story when light has to travel through a substance. It turns out that graphene, a substance made up of a single layer of interconnected carbon atoms, can slow light down by more than a hundred times.
Now you can make electrons go faster than that by applying a voltage to the graphene. What you get is analogous to a sonic boom produced by an airplane flying faster than the speed of sound - instead of hearing a boom, you see a faint glow of light.
The electrons disturb the graphene atoms, which emit light energy as they recover to their undisturbed state.
The calculations of the research team found the energy conversion is most efficient - almost 80 per cent - when the speed of the electrons is very similar to that of light in graphene.
The team is now trying to make it happen in a physical piece of graphene, but it is not as easy as it sounds.
For example, researchers must first check the graphene for defects, such as wrinkles, and ensure that it really is a single layer of atoms, using a scanning electron microscope.
Associate Professor Christian Nijhuis, a graphene specialist at the National University of Singapore's (NUS) Centre for Advanced 2D Materials, said that the small size, high energy-conversion efficiency and high frequency of the MIT group's set-up would make it an excellent candidate for next-generation electronics, but experimental confirmation of their theoretical findings is first needed.
Prof Nijhuis added that his own research group at NUS is working towards similar goals using quantum mechanics, and that technologies developed in this broad area may find applications in electronics within 10 years.
If successful, Dr Wong noted, his team's graphene device could be called on for anything requiring optical energy, not just computers. For example, it could offer a more precise and efficient way to deliver radiation for tumour treatment or airport X-ray machines.
Said Dr Wong: "Right now, we're just cautiously optimistic... but, at the same time, we can already see so many potential applications coming out of it."