How to beat the speed of light?

The speed of light is extremely fast, 300 thousand kilometers per second, which has become the speed limit of material and information transmission in the universe. Ancient Homo sapiens could not communicate with each other effectively on the vast continent, just because they lacked modern tools. Once trains, telegrams, planes, ships, etc. All have stepped onto the historical stage, and different civilizations around the world are bound to be closely linked.

In the future, the problems encountered by space immigrants will be more serious. The gap between immigrants from different planets is caused by the basic physical theory, because the speed of light can't meet the needs of our interstellar travel, and the superluminal spacecraft and communication means violate the special theory of relativity.

First of all, the insurmountable speed of light

Special relativity tells us that the speed of light is the fastest travel speed in the universe, that is, it cannot exceed the speed of light. This is a bit counterintuitive for ordinary people. In our daily experience, speed can be superimposed. For example, Xiao Li sits on a high-speed train with a speed of v=200km/h, and then throws a baseball along the direction of the train in the carriage. For Xiao Li on the train, the speed of the baseball he throws is U = 100 km/h, and for Xiao Zhang, an observer outside the window, the speed of this baseball is the speed of the train plus the speed of the baseball relative to the train, reaching V+U = 300 km/h.

In this baseball experiment, we get the speed (v+u) of baseball relative to the ground by superposition. This practice is called Galileo transformation. In galilean transformation, the measurement of space is absolute and has nothing to do with the reference system; The measurement of time is also absolute and has nothing to do with the reference system. This is Newton's absolute view of time and space.

So if Xiao Li turns on the flashlight on the moving train, won't the speed of the light beam emitted relative to the ground exceed the speed of light?

/kloc-at the end of 0/9, experimental physicist Albert? Albert Abrahan Michelson and Edward? Edward Morley found that galilean transformation was wrong about the propagation of light. No matter in which reference frame the speed of light is measured, a constant value of about 300,000 km/s is obtained. In other words, if you turn on the flashlight on the train, the light emitted by the flashlight will travel at the same speed for both the passengers on the train and the observers on the ground outside the train.

1905, Albert Einstein proposed in his special theory of relativity that all physical laws should be based on two foundations: the principle of invariance of light speed and the principle of relativity.

Relativity holds that Lorentz transformation should be used to transform the motion equations of objects between different reference systems, not galilean transformation. But when the object is moving at a low speed (much less than the speed of light), galilean transformation is a good approximation of Lorentz transformation. Lorentz transformation was originally used to reconcile the contradiction between classical electrodynamics and Newtonian mechanics established in19th century, and later became the basic equation of special relativity.

The special theory of relativity also shows that when the speed of baseball approaches the speed of light, its inertia tends to infinity. No matter how powerful you are, you can only throw a baseball close to the speed of light, and you will never reach the speed of light. In a large particle accelerator, elementary particles are accelerated to a degree very close to the speed of light, and the prediction of special relativity has been fully tested by physical experiments.

However, Dr. Li Ran, a researcher at China Academy of Sciences, believes that theoretically, under certain conditions, there is still hope for superluminal travel.

Second, change the space distance to beat the speed of light.

The limit of the speed of light has set serious obstacles for human beings in matters (energy), information transmission, space travel and so on. Whether there is a way to break it, theorists have put forward many fantastic ideas.

According to the general theory of relativity, the existence of matter will bend the space and there is a gravitational lens effect. If we put another star (equivalent to a lens celestial body) between the distant star and the observer, the space curvature caused by this star will distort the propagation line of light emitted by the background star. At some point, the light emitted by stars may reach the earth in several ways. Observers on earth will see images of the same star in different parts of the sky.

Because of the different paths, each beam of light travels a different distance. If a distant star dies and produces a supernova explosion, observers on earth will see the supernova light up in several different positions in the sky, indicating that the distance between the earth and the star changes with the curvature of space.

Scientists believe that if we want to create shortcuts in space, we need to completely change the geometry of space. For example, making a wormhole in the space-time mentioned in the science fiction movie, namely Einstein-Rosen Bridge. Mathematically speaking, wormhole is a special solution of general relativity gravitational field equation, which can connect two distant places in our space from a high-dimensional space, that is, two shortcuts in space.

American physicist John? John archibald wheeler pointed out that in quantum bubbles, wormholes may continue to connect and disappear. An extremely developed civilization may have a way to pick out a suitable wormhole from a quantum bubble and expand it into a tunnel for travelers to cross.

Astronomer Carl? Carl edward sagan's popular science book "Time and Space Contact" describes time and space travel in this way. He designed a wormhole tunnel in space-time distorted by a black hole. The heroine was teleported to Vega 26.5 light-years away, and 1 hour later she appeared in the space next to Vega. This transmission speed has obviously exceeded the speed of light in space.

Third, manipulate space expansion to beat the speed of light.

Another hyperspace travel scheme involves the expansion of manipulation space, such as the curvature-driven engine mentioned in Three-body. As we all know, all galaxies are moving away from the Milky Way, because space is expanding. The farther away the galaxy is from us, the faster it will go backwards. Because this expansion is completely spatial, it is not limited by the speed of light. As long as the galaxy is far enough away from us, its retrogression speed can completely exceed the speed of light.

If we can manipulate space-time and make it expand unevenly, it may be possible to make the speed of the spacecraft exceed the speed of light. 1994, Mexican physicist miguel alcubierre put forward the theory of curvature-driven engine, which drives spacecraft by transforming space-time itself.

He pointed out that a space-time bubble can be constructed, so that the positive space-time is compressed, while the reverse space-time is expanded, and the curvature of space-time produces huge positive gravity, thus achieving the effect of curvature engine.

This bubble in time and space is a bit like a boat paddling in time and space, except that it does not stir the water surface, but stirs time and space. Once the bubble is built, the spacecraft only needs to stay in the bubble and can move with it. Bubbles travel through time and space before and after bending, reaching superluminal flight.

However, the construction of space-time bubbles requires a lot of exotic substances with negative gravity. Belgian scientist Brooke calculated that to build a space-time bubble, at least foreign matter with a mass greater than that of the sun is needed. This is obviously far beyond the current ability of human beings.

Four. Concluding remarks

It should be pointed out that in order to break the insurmountable limit of the speed of light, the idea of changing the spatial distance through wormholes and controlling the expansion of space-time through curvature-driven engines is only the initial stage of theoretical exploration by scientists, and even just some bold guesses, which will not be realized in the foreseeable future.

However, these do not seem to violate the existing scientific principles. We need to be curious. We still have dreams.