According to foreign media reports, in 1676, Danish astronomer ole Roemer calculated that light propagated at a limited speed by studying the operation of Io. Two years later, Christian Huygens, a Dutch mathematician and scientist, became the first person to try to determine the actual speed of light based on the data collected by Romer.
At that time, the speed of light proposed by Huygens was 211000 km / s, which did not meet the current accurate standard. Now we know that the speed of light in the "vacuum" reached 299792 km / s, but Huygens once evaluated that light propagated in space at an incredible speed.
According to Einstein's special theory of relativity, light travels so fast that no object in the vacuum of the universe can travel faster than light. Jason cassibry, associate professor of Aerospace Engineering at the center for propulsion research at alabar State University, confirmed that we cannot travel faster than the speed of light in space!
Is this conclusion correct? Perhaps not. When light does not travel in a vacuum, does it still follow the "law that the speed of light cannot be exceeded"?
Claudia de Rham, a theoretical physicist at Imperial College London, said that technically speaking, the statement that "nothing can surpass the speed of light" is not entirely correct, at least in a non vacuum environment, but she stressed that there are some factors to be taken into account.
Light has both particle characteristics and wave characteristics, so light can be regarded as both particle (photon) and wave, which is wave particle duality. "If you think of light as a wave, there are 'many reasons' to explain why some waves travel faster in a medium than white light (or achromatic light). One reason is that when light passes through a medium, such as glass or water droplets, light of different frequencies or colors travels at different speeds," RAM said
According to an article by the University of Wisconsin Madison, the most obvious example occurs in a rainbow. The longer and faster red wavelength is at the top of the rainbow, while the shorter and slower purple wavelength is at the bottom of the rainbow. However, when light travels in a vacuum, the situation is different.
Professor Rhett Allain, a physicist at the University of Louisiana in the southeastern United States, said that all light is a form of electromagnetic wave, and they all have the same velocity in vacuum - 3 × 10 ^ 8 m / s, which is equivalent to the speed of radio waves and gamma rays.
Therefore, according to ram's theory, the only thing faster than the speed of light (a bit contradictory) is light itself, although it only occurs in a non vacuum environment. But it is worth noting that no matter what medium it is, the speed of light will never exceed 299792 km / s.
Cosmic angle
According to casbury, there are other factors to consider when discussing objects that travel faster than the speed of light. He said: "some parts of the universe are expanding faster than the speed of light and far away from the earth. For example, the Hubble Space Telescope recently observed a distant star called earendel, which released light 12.9 billion years ago. However, due to the constant expansion of the universe, the elendel star has been far away from the earth since its formation, so its current distance from the earth is not 12.9 billion light-years, but more distant.
In this case, space-time expands continuously, but the matter in space-time still moves within the speed of light. So obviously, as we know, no object will exceed the speed of light, but is it possible to exceed the speed of light?
Ram said that Einstein's special relativity and general relativity were based on "the principle of relativity between the concepts of space and time", but what does this mean? If someone can move faster than the speed of light and carry information, their concept of time will be more distorted than our concept of time. In some cases, the future may affect our past and the whole reality structure will lose its meaning.
This means that it is impossible for human space-time travel to exceed the speed of light, but will one day we be able to develop new technologies and materials and drive spaceships that exceed the speed of light to and from space? "Theorists have proposed various types of warp bubbles that can travel in time and space at superluminal speeds," casbury said
The human body cannot travel at the speed of light
Ram said: "We can imagine that we can realize extrasolar communication at the speed of light, but it is impossible to launch a real person at the speed of light, because we cannot realize human space-time travel at the speed of light. Even under a very ideal condition, such as the human body accelerating at a constant speed, in fact, it is difficult for human beings to obtain an accelerating space travel technology. We will never reach the speed of light. Maybe we will be very close to light Speed, but cannot exceed the speed of light. "
Kasiburi confirmed this. He said: "on the premise of ignoring the theory of relativity, if you accelerate at the speed of 1g of the earth's gravity, you can reach the speed of light for a year. In fact, people can never reach this speed, because when the human body approaches the speed of light, the mass and energy of the human body will continue to increase, close to infinity."
Similarly, Alan believes that it is impossible to exceed the speed of light, but as kasbury believes, if humans want to explore distant exoplanets, it is not actually necessary to reach the speed of light. He pointed out that the only way we can understand faster than the speed of light is to use some type of wormhole in space-time. Using this strategy may not need to achieve space-time travel beyond the speed of light, but provide a shortcut to other areas of space.
However, kasiburi is not sure whether wormholes are the most realistic choice for speeding space travel. He said: "according to the special solution of Einstein's field equation, wormhole theory is possible. Basically, if wormholes exist, it will be a shortcut between two destinations, but I don't know whether wormholes can be built or how to build wormholes." (Ye Qingcheng)