@Gaff: Because its a completely hypothetical energy. Scientists observed that for some reason the universe was still expanding, even though gravity should eventually stop the expansion and eventually force the universe to contract. To compensate for this, they decided the universe must be full of some "thing" which keeps expanding it-this they named Dark Energy and declared that around 70 percent of the universe is made up of it.@Gaff
Science has not observed Dark Energy, nor does science claim to know what it is.
Its was simply thought up to explain the data.
@hitsusatsu11Speaking of things that are "unobservable", hypothetical", "thought up to explain the data"...
So, according to you:
1. Unexplained phenomena;
2. Think of something;
This is how science is done, right?
There's something missing here...