When gravitational waves pass through the observer, the observer will find that space-time is distorted by strain effect. When gravitational waves pass by, the distance between objects will increase and decrease rhythmically, which is different from the frequency of gravitational waves. The intensity of this effect is inversely proportional to the distance between the sources that produce gravitational waves. The orbiting double neutron star system is predicted to be a very strong gravitational wave source. When they merge, because of their huge acceleration when they orbit near each other. Because it is usually far away from these sources, it has little influence when observed on the earth, and the deformation influence is less than 1.0E-2 1. Scientists have confirmed the existence of gravitational waves with more sensitive detectors. ALIGO is the most sensitive one at present, and its detection accuracy can reach 1.0E-22. More space observatories are being planned (eLISA project of European Space Agency, Taiji project of China Academy of Sciences and Qin Tian project of Sun Yat-sen University).
Gravitational waves should be able to penetrate where electromagnetic waves cannot. Therefore, it is speculated that gravitational waves can provide observers on earth with information about black holes and other strange objects in the distant universe. These celestial bodies cannot be observed by traditional methods, such as optical telescopes and radio telescopes, so the gravitational wave astronomy society gives us a new understanding of the operation of the universe. Gravitational waves, in particular, are more interesting because they can provide a way to observe the very early universe, which is impossible in traditional astronomy because the universe is opaque to electromagnetic radiation before reunion. Therefore, the accurate measurement of gravitational waves can enable scientists to verify the general theory of relativity more comprehensively.
(Figure 1)
Figure 1: gravitational spectrum; Frequency range corresponding to different gravitational wave sources (note that the frequency is the value after logarithm), period. And the corresponding detection mode.
By studying gravitational waves, scientists can tell what happened at the initial singularity of the universe. In principle, gravitational waves exist at all frequencies. It is impossible to detect extremely low frequency gravitational waves, and there is no reliable gravitational wave source in extremely high frequency region. According to Stephen Hawking and Werner israel, the frequency of gravitational waves that may be detected should be between 1.0E-7 Hz and 1E 1 1Hz.
Gravitational waves constantly pass through the earth; However, even the strongest gravitational wave effect is very small, and these sources are far away from us. For example, the gravitational wave of GW 1509 14 in the final stage of fierce merger reached the earth after crossing1300 million light years. The most time-space ripple only changed the proton diameter of LIGO 4 km arm, which is equivalent to bringing the solar system to.
The distance between our nearest stars changes the width of a thin line. This extremely small change, if we don't borrow an unusually sophisticated detector, we can't detect it at all.
(Figure 2)
Figure 2: LIGO's two observation stations detected the same gravitational wave event. The above is the observation curve, and the following is the fitting result after comparing with the theory. (Excerpted from an article by LIGO)