It’s the dream of scientists and astronomers; the ability to travel at or faster than the speed of light. Imagine what would be possible if we could reach Mars or some distant star at a fraction of the time it would take with currently available technology. But is it even possible to travel faster than light? In theory, no. Except in certain environment, according to the Cherenkov effect.
In the year 1905, the theoretical physicist Albert Einstein enunciated the theory of relativity that made him famous. According to the latter, nothing or nobody can move in a vacuum at a speed greater than the speed of light, namely about 300,000 kilometers per second.
In truth, it is not the speed itself that can not be exceeded. It is rather the energy necessary for the propulsion of the object which is practically untenable. In fact, according to the theory of restricted relativity, an object that undergoes acceleration gains mass. By reaching the speed of 300,000 km/s, it could potentially acquire an infinite mass. But it would be necessary to supply this object with sufficient energy, which moreover is proportional to its mass.
We can not move in a vacuum at a speed beyond the speed of light. But in some environment, it seems that it is possible. This is called the Cherenkov effect, a phenomenon discovered in 1958 by the Russian physicist Pavel Cherenkov. A study that won him the Nobel Prize in physics.
Indeed, Einstein’s theory of special relativity is true for objects that move in a vacuum. The Cherenkov effect is only possible in a given medium, and it occurs when a particle moves faster than light. Thus, although it is not possible for a particle to exceed the speed of light in a vacuum, this does not prevent a particle from moving faster than light in certain environments – for example, water. When this is the case, the particle emits an intense light of blue color. This is called Cherenkov radiation.