Since I’ve already done a blog on dark matter I thought why not do one on dark energy as well! Like dark matter, the existence of dark matter has yet to be proven. Despite this, dark energy is theorized to ‘exist’ in very large quantities. Current models have dark energy occupying 68.3% of the universe. So if we can’t prove dark energy exists why do physicists believe it exists? Well because it’s the only thing that would explain why the universe is accelerating. We know from red shift that the universe must not only be expanding but is also accelerating. Thus some sort of energy must be present for the universe to accelerate. The fact that we can’t prove dark energy has lead to problems in predicting the future of the universe. If all dark energy is eventually consumed, the gravitational force of matter could cause the big crunch where the universe collapses back onto itself. Or dark energy could end up eventually overpowering gravity and the strong nuclear forces, ripping atoms apart leading to the big rip. Or the force outwards eventually equals the gravitational force and the universe stops expanding but doesn’t contract.