Living at the center of the universe

The center of mass of an object is defined as the mass-weighted average position of all the particles that comprise the object. The significance of the center of mass of an object can be seen by looking at its dynamics. The time derivative of the center of mass gives its velocity, assuming that the object's mass remains constant over time. Furthermore, the total linear momentum of an object can be seen as the linear momentum of a single particle of the object's total mass moving with the...

No object with a finite mass can travel faster than the speed of light in a vacuum. This fact has an interesting consequence in the domain of extremely high gravitational fields.
The minimum speed required to launch a projectile from the surface of an object to which it is gravitationally bound so that it eventually escapes the object’s gravitational field is called the escape velocity. The escape velocity is independent of the mass of the object. Merging the idea of escape velocity with the...

Although black holes were theoretically postulated in the 1920s, they remained outside the domain of observational astronomy until the 1970s.
Their closest cousins are neutron stars, which are composed almost entirely of neutrons packed against each other, making them extremely dense. A neutron star has the same mass as the Sun but its diameter is only a few kilometers. Therefore, the escape velocity from their surface is close to the speed of light.
Not until the 1960s, when the first neutron...

Any object that obeys Newton's second law of motion is made up of a large number of infinitesimally small particles. Objects in motion can be as simple as atoms or as complex as gymnasts performing in the Olympics. The motion of such objects is described about a point called the center of mass of the object. The center of mass of an object is a point that acts as if the whole mass is concentrated at that point. The center of mass of an object with a large number of infinitesimally small...

The center of mass is the point at which the total mass of an object can be said to be concentrated. It is a fundamental principle in mechanics and physics that applies to all objects regardless of their shape or size. The center of gravity is the point at which an object’s weight appears to be concentrated and can be used to balance the object perfectly.
The knowledge of the center of mass can also help us to describe and predict the motion of objects. For example, when a ball is thrown into...

In the early 17th century, German astronomer and mathematician Johannes Kepler postulated three laws for the motion of planets in the solar system. He formulated his first two laws based on the observations of his forebears, Nikolaus Copernicus and Tycho Brahe.
Polish astronomer Nikolaus Copernicus put forth a theory that stated a heliocentric model for the solar system. According to this heliocentric theory, all the planets, including Earth, orbit the Sun in circular orbits.
On the other hand,...