While it is true that black holes themselves cannot be seen, their effects on surrounding matter can be observed and studied. Here are a few ways we can learn about black holes:
Stellar motion: Black holes have a strong gravitational pull, which can affect the motion of stars and other celestial objects near them. By observing the motion of these objects, astronomers can infer the presence of a black hole.
Accretion disks: Black holes can draw matter into a swirling disk of gas and dust, known as an accretion disk. The intense heat and radiation emitted by the disk can be observed using various telescopes, allowing astronomers to study the black hole indirectly.
Gravitational waves: Black holes can cause ripples in the fabric of spacetime, known as gravitational waves. By detecting these waves, scientists can learn about the properties of the black holes that created them.
X-rays: Matter that is being drawn into a black hole can become extremely hot, emitting X-rays that can be detected by specialized telescopes.
Simulations: By using supercomputers to simulate the behavior of black holes, scientists can study their properties and make predictions about their behavior.
Overall, while we cannot directly observe black holes, the effects they have on surrounding matter provide a wealth of information for astronomers and astrophysicists to study and understand these mysterious objects.
Exploring the Unknown 