When someone says to another that he is an empty place, these are offensive words.From a moral point of view,but from a physical point of view, this expression is very true,and is calculated using ordinary physics,or more precisely quantum physics.And this can be explained by the example of neutron stars.
A neutron star is a close relative of a black hole that does not" collapse " to the state of a black hole. Therefore, neutron stars, unlike black holes, can be observed . These are amazing objects. They are so dense that a star with a radius of just 10 kilometers is more than twice as heavy as the Sun.
There are such dense stars that if you take a teaspoon of the matter of such a star, it will weigh a billion tons. Neutron stars are made up of matter that doesn't exist on Earth. They are also unusual because they rotate very quickly. They usually rotate around their axis several times per second, but there are known stars that do this at a speed of several hundred times per second.