Tag: black holes

As we have described a black hole, we never can observe one of them because they would not reflect or emit any radiation or particle. But there are certain effects that can be detected. One of these effects is the gravitational effect on a neighboring star.

Suppose a binary star system (two stars so close to turning the one around the other) in which one of the stars is visible and than we can calculate its distance from Earth, and its mass. The visible star will make a few oscillatory movements in space due to the gravitational attraction of the invisible star. From these movements we can calculate the mass of the invisible star .

If this invisible star exceeds a mass of about 2.5 times the mass of our Sun, we must assume that it’s a black hole.

Continue reading “Detection of black holes”

  According to the general relativity theory of Einstein, near a large mass, time happens slowly due to the gravitational action.

  Einstein deduced (as we read in his book “The Meaning of Relativity”) the following formula

(7) Continue reading “General relativity and black holes”

It is possible to find the relationship between the mass and the radius of a spherical black hole keeping in mind that the maximum speed that could reach an object, according to the theory of relativity, it is the speed of light.

The scape velocity in the surface of a spherical star will be the maximum velocity that could reach an object in order to stay in orbit around the star. This will happen when the kinetic energy of one object is equal to the potential energy due to the star gravitational attraction. Continue reading “Special Relativity Theory And Black Holes”