In the famous science fiction novel "Three-Body", the Trisolarans who came to Earth from Proxima Centauri, because the human "Gravity" spacecraft used "gravitational waves" to broadcast the coordinates of the three-body world to the universe, and eventually the home was destroyed by the higher civilization.
So the question is, what exactly is a "gravitational wave"? Can humans really use gravitational waves to emit signals or make gravitational waves into weapons? Will the gravitational wave weapon be the ultimate weapon in the universe?
<h1 class="pgc-h-arrow-right" What exactly are gravitational waves > data-track="3"? </h1>
It all starts with a debate spanning more than 200 years. There are two famous miracle years in the history of science, one is called: Newton's Miracle Year, and the other is called: Einstein's Miracle Year.
Newton's Miracle Year was around 1666, when he proposed the laws of mechanics and made the beginning of the law of universal gravitation. The Einstein Miracle Year came in 1905, when he came up with four seminal scientific achievements, one of which we later called special relativity.
As we all know, the theory of relativity is divided into special relativity and general relativity. General relativity is actually a generalization of special relativity, and at the same time can be used to make a more profound exposition of "gravity". The focus of this debate is actually: gravity. What is more essential is actually: the view of space-time.
Newton believed that time and space are independent of each other and are absolute, and that the time span of "one second" and the spatial span of "one meter" are the same for any observer and do not change because of different states of motion; Einstein believed that time and space cannot be viewed independently, but affect each other, and that the time span of "one second" and the spatial span of "one meter" may be different for observers in different states of motion. Therefore, he called time and space together: space-time.
Under the two men's different assumptions, Newton believed that gravity is a kind of over-range action that can be transmitted instantaneously through time. Einstein believed that there is no gravitational force at all, the essence of gravity is the curvature of space-time, the object is only moving along the geodesic line of space-time (the shortest distance in the four-dimensional space-time), and the speed of gravitational force is the speed of light.
To put it bluntly, the moon orbits the earth because the earth bends the surrounding space-time, and the moon is only moving along the "ground" of space-time.
Newton and Einstein had different interpretations of gravity, requiring experimental physicists to make observations to determine whose theory was more precise. In 1919, astronomer Eddington led a team to observe a total solar eclipse on the West African island of Principe and photographed the positions of stars near the sun during a total solar eclipse.
According to Newton's law of universal gravitation and Einstein's theory of general relativity, the light rays of these stars are deflected near massive celestial bodies, albeit to varying degrees. By analyzing the photographs, Eddington found that the actual situation was more consistent with the results of Einstein's predictions, which led to widespread acceptance of Einstein's general theory of relativity in academic circles, making it the mainstream theory of explaining gravity.
According to general relativity, the essence of gravity is the curvature of space-time, gravity is not a step-by-distance action, and the speed of propagation is the speed of light. Therefore, gravity, in the process of transmission, will produce ripples in space-time, which is also known as gravitational waves.
We can make a not very appropriate analogy to understand, space-time is like the surface of the water, objects with mass are like space-time, when we throw a stone on the surface of the water, it will ripple, this ripple is like a gravitational wave. However, the above is only the speculation of theoretical physicists, do gravitational waves really exist?
In 2016, the LIGO team detected evidence of gravitational waves.
In 2017, three ligo scientists, Reiner Weiss, Barry Ballish and Kip Thorne, won the Nobel Prize in Physics for their successful observation of gravitational waves. That is to say, gravitational waves have been confirmed to exist, so the question is, what is the use of gravitational waves?
In fact, the development of science has always been ahead of the development of science and technology, not to mention the practical application of gravitational waves, Einstein's theory of relativity can be put into practical application of the scene is not much. However, the discovery of gravitational waves has played a decisive role in promoting the development of science itself. For example, the establishment of gravitational wave astronomy, in cosmology, through the study of primordial gravitational waves, it is possible to understand what happened within 380,000 years after the birth of the universe.
<h1 class="pgc-h-arrow-right" Data-track="17" can > gravitational waves be used as weapons? </h1>
Theoretically, gravitational waves could be used for communications, radar detection, and even weaponization. Gravitational wave detection is now the most important use, and many countries have invested in this regard, hoping to accurately identify gravitational waves in the universe. However, the fact that humans themselves emit gravitational waves through the device to communicate is now highly likely to be achieved. As for the reasons, we'll talk about them together later.
As for weapons, gravitational waves can be used to resonate massive objects, thereby shaking them into pieces. However, this is only in the concept, in fact, it is difficult to achieve, and it is not necessary.
Whether it's humans themselves firing gravitational waves to communicate, or crafting weapons. Essentially, gravitational waves need to be emitted. The problem, however, is that gravitational waves are not so easy to emit. Objects with small masses, although they also have gravitational waves, are very weak and almost invisible. If you want to produce strong gravitational waves, you need massive objects. The gravitational waves that human gravitational wave detectors can detect come from the merger of two black holes or the merger of two neutron stars, which belong to the densest and most massive objects in the universe.
The gravitational waves produced by the merger of the two black holes in the distance are not enough to shatter the earth, which is enough to produce gravitational waves that shatter the object, which is very massive.
If humans can really create objects with such massive mass, there is no need to use gravitational waves to shatter objects. Because, you only need to throw the object to the opponent, the object's strong gravity is enough to detonate the opponent.
For example, we only need to put a neutron star or black hole near the earth, and the earth will be torn to pieces.
Therefore, in such a situation, it is a bit redundant to use gravitational waves, and there is a feeling that you can obviously shoot your opponent with a submachine gun, but you have to take a kitchen knife without a blade to play with the opponent with a cold weapon.
Therefore, gravitational waves may be used for communication in the future, but they are too difficult and the probability of realization is not high, let alone used as weapons.
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