Can anything travel faster than light?

Light has properties like both a particle and a wave, able to travel at speeds of up to about 300,000km per second in a vacuum.

In 1676, while studying the moving Jupiter's moon Io, the Danish astronomer Ole Romer calculated that light travels at a finite speed. Two years later, based on data Romer collected, Dutch scientist Christiaan Huygens became the first person to attempt to determine the true speed of light, according to the American Museum of Natural History, New York City.

Illustration of light beams.

Huygens gives the figure 211,000km per second. This number is not accurate by today's standards, when scientists measure the speed of light in a vacuum is about 299,792 kilometers per second. However, his calculations also showed that light travels at an amazing speed.

According to Albert Einstein's theory of special relativity, light travels so fast that in a vacuum, nothing in the universe can move faster.

"We can't travel in the vacuum of space faster than light," said Jason Cassibry, an associate professor of aerospace engineering at the Center for Propulsion Research at the University of Alabama.

So when light is not in a vacuum, is this still true?

Technically, the very claim that "nothing can travel faster than the speed of light" is not entirely accurate, at least in a non-vacuum environment, according to physicist Claudia de Rham theory at Imperial College London.

Light exhibits the same properties as both a particle and a wave, so it can be thought of as both a particle (photon) and a wave. This is called wave-particle duality.

If you think of light as a wave, there are many reasons why some waves can travel faster than white (or colorless) light in a given medium, according to de Rham. One reason is that when light travels through a medium - for example glass or a drop of water - different frequencies or colors of light travel at different speeds.

The most obvious visual example of this happens with a rainbow. Rainbows typically have red wavelengths (longer and faster) at the top, violet wavelengths (shorter and slower) at the bottom, according to the University of Wisconsin - Madison.

Rainbow over Harper Lake in Louisville, Colorado, USA.

However, when light travels through a vacuum, this is no longer correct. "All light is a type of electromagnetic wave and they all have the same speed in a vacuum. This means both radio waves and gamma rays have the same speed," said Rhett Allain, a professor of physics at the University of California. Southeast Louisiana University, explained.

So, according to de Rham, the only thing that can travel faster than light is light, but only when not in a vacuum of space. Note, regardless of the environment, light never exceeds its maximum speed of 299,792 kilometers per second.

However, according to Cassibry, there are several points to consider when talking about things that move faster than the speed of light. "There are parts of the universe that are expanding away from us at a speed faster than the speed of light because space-time is expanding," he said.

For example, the Hubble space telescope recently detected 12.9 billion-year-old light from the distant star Earendel. However, because the universe is expanding at every point, Earendel is also moving away from Earth. It has been moving like that since its formation and is now 28 billion light-years from Earth.

In this case, space-time is expanding, but matter in space-time is still moving within the limits of the speed of light.

Earendel's position in this Hubble image. (Photo: NASA)

"We can envision transmitting information at the speed of light through extrasolar systems. But transporting people at the speed of light is not possible because we cannot accelerate ourselves to such a degree. so," said de Rham.

"Even under ideal conditions, where we have the ability to continuously accelerate ourselves at a constant rate - ignoring how technology helps people accelerate continuously - we will never now really reach the speed of light. We can get close, but never get there," she added.

Cassibry also agrees with this opinion. "Relativity aside, if you accelerate at 1G (Earth's gravity), it will take you a year to reach the speed of light. However, you will never really reach that speed because when you do starting to approach the speed of light, your mass energy increases, approaching infinity," he said.

"One of the few cheats that can be used is to expand and contract space-time, thereby drawing the target closer to you. There seems to be no fundamental limit to the rate of expansion or contraction. space-time, which means we could get close to this speed limit one day," added Cassibry.

Traveling faster than light is far-fetched, Allain said, but notes that if humans want to explore distant planets, it may not really be necessary to reach such speeds.

He thinks wormholes could be a solution if people want to move fast. "This doesn't actually make us go faster than light, but does provide us with shortcuts to several locations in the universe," he said.