We've all heard of Black Holes and how their massive weight and gravitational influence shape our galaxies. In fact, it is now estimated that most galaxies have a supermassive black hole residing at their centers which may have played a large part in facilitating growth at the early stages of the galaxy's formation.
A Black Hole's gravitational pull is strong enough to prevent light from escaping it. Light travels at approximately 299,792,458 meters a second (~186,000 miles per second). One can only imagine what type of extreme gravitational force would be necessary to keep even light from escaping the depths of a Black Hole.
An artist's conception of a Black Hole. Source: zmescience.com
However, more intriguing than the Black Hole's massive gravitational pull and weight is its size. What many don't seem to know about a Black Hole is that it is infinitely small. In fact, a Black Hole is smaller than a grain of sand. Doesn't make sense, does it? How something so small can weigh so heavy? That's the exact problem with Black Holes that physicists have been working on for years now.
There are two types of theories at work at the inside of a Black Hole, which makes it more unique than almost any other interstellar object.
Atomic properties at the quantum level. Source: Wikimedia Commons
The first is that since the Black Hole is nearly infinitely small, physicists must utilize the laws of quantum mechanics in order to understand the properties at the tiny level. For those of you who don't know, quantum mechanics is the "weird" world of physics where particles don't behave as we would expect them to in the macro world. For instance, random occurrences occur that have probabilities attached to them; however, their nature still appears somewhat random to scientists. This causes a problem because as we move up the ladder and look at what is going on at the macro level, patterns appear (i.e., electrons and protons, their respective behaviors).
A conceptual image of the laws of general relativity (ball rolling and curving space-time). Source: topnews.net.nz
The second theory important to the study of Black Holes is general relativity. A theory by Albert Einstein that revolutionized our understanding of the universe; it plays an important part in understanding Black Holes due to their gargantuan mass. General relativity is necessary in order to understand how massive objects such as stars, planets, and other objects in the universe move due to curvature in space-time. And due to the fact that Black Holes have such high masses, the laws of general relativity are important in understanding how they should behave. This brings us to the main problem with Black Holes.
Quantum mechanics and general relativity do not seem to like each other mathematically. They are in a sense, almost two different instruments that are playing their own tunes to the universe. They both have this harmonious way of summarizing how things act in their respective worlds (microscopic level for quantum mechanics, macroscopic level for general relativity. However, both theories seem to hate each other mathematically when brought together. Things don't quite add up--the math falls apart. And the problem with Black Holes is that they are infinitely small and infinitely massive--meaning that we would need to use both theories in order to understand Black Hole entirely.
Many physicists are working on a grand unification theory to help solve this problem in Physics. Theories such as String Theory and "The God Equation" are constantly being worked upon by physicists around the world in order to reach a grand unification theory that would bring together the laws of quantum mechanics and general relativity in one. Until then, we can only imagine how harmonious and powerful such a unified theory can be.