The Schwarzschild radius

The Schwarzschild radius is named after the German astronomer Karl Schwarzschild. It refers to the radius of a spheroid (such as the sun or other stars/planets) such that if the sphere was to be compressed within that sphere, the escape velocity from the surface would equal the speed of light. In layman terms, everything has a Schwarzschild radius. If you were to pack all the matter/mass of an object into this radius, it would collapse into a black hole.

An example of an object in it's Schwarzschild radius is a black hole. Once a star collapses on its core and below this radius, and light cannot escape the event horizon. The Schwarzschild radius is given by the equation :

Where G is the gravitational constant, M is the mass of the object and c is, of course, the speed of light.

The Schwarzschild radius for earth can be calculated by plugging in the values for the respective variables : 

Which turns out to be approximately 0.008857 m or 8.857 * 10^-3 m  That means, the earth will have to be squished down to a radius of 8.857 * 10^-3 m to become a black hole. Several other values for different bodies are given below : 

In fact, everything has a Schwarzschild radius. Taking the average human mass as an example, I can input the following values in the equation : 

To get a value of about 1.20 * 10^-25 m. So, the average human needs to have a 'radius' of the mentioned value in order to become a black hole.