Dark Energy and the Joy of Being Wrong
From Adam Frank at 13:7:
Sometimes nature just throws you a loop. All your carefully laid plans, all your exquisite calculations, all your deeply held beliefs and expectations get blown away in the simple eloquence of real data from the real world. That is how Dark Energy made its appearance into the world of cosmology. Its not just that folks weren’t expecting it. They were, in fact, expecting the very opposite.
Dark Matter was “discovered” (inferred really), based on observations over decades of the gravitational influence it exerts on matter we can see (the stuff we are made of). Dark Energy was discovered in a similar way, except that it arrived all at once in one big, fat surprise package.