Well, Einstein was just one of thousands of physicists in the 20th century who contributed small steps in understanding the universe, and of course tremendous progress was made. The laws of physics, which include Maxwell's Equations and Special Relativity (which, itself, includes Newton's Laws, and so is not separate from it), are known well enough to predict the behavior of the universe back to about a billionths of a second after time began. Thousands of measurements have assessed these ideas and led to the rejection of alternative explanations - the scientific method. Is our knowledge complete? Nope. Never said it was. A good scientist knows the limits of knowledge. But a good scientist also knows that you don't give up, and you keep using an idea until it breaks. I hope relativity and quantum physics break in my lifetime, so we can learn the better idea. Until they stop working, we'll keep testing them.