http://www.theguardian.com/news/2015/nov/04/relativity-quantum-mechanics-universe-physicists

At present physicists have two separate rulebooks explaining how nature works.
 
There is general relativity, which beautifully accounts for gravity and all of the things it dominates: orbiting planets, colliding galaxies, the dynamics of the expanding universe as a whole. That’s big.
 
Then there is quantum mechanics, which handles the other three forces – electromagnetism and the two nuclear forces. Quantum theory is extremely adept at describing what happens when a uranium atom decays, or when individual particles of light hit a solar cell. That’s small.
 
Now for the problem: relativity and quantum mechanics are fundamentally different theories that have different formulations. It is not just a matter of scientific terminology; it is a clash of genuinely incompatible descriptions of reality.