Dark Energy By Chris Malafis & Amit Sheth

Discovery Two competing groups from different observatories were trying to prove the deceleration of the expansion of the universe. Instead they found out that it is accelerating. This means that there is some force that goes against gravity.

Cosmic Expansion Cosmic Expansion is the idea behind the expansion of the universe. As time goes on, astronomical bodies move farther and farther away from our galaxy. If this began earlier in the universe, galaxies and other huge structures would not have been able to form.

Cosmic Expansion

What is Dark Energy? A form of energy that makes up approximately seventy percent of the universe’s energy. However, scientists know very little about the concept. It is not observable because it doesn’t emit light.

Nature of Dark Energy It is distributed throughout the universe in cobweb like filaments. The first half of the universe’s life galaxies have collided into each other to form clusters which spread out at a decelerating rate. Since then, the universe has been accelerating and galaxies stopped merging.

Nature of Dark Energy In the last six billion years, the formation of structures like stars, black holes, and quasars has decreased. Scientists believe that Dark Energy is the counterpart to gravity, and carries particles as well. It is believed that eventually Dark Energy will overpower gravity and split all molecules and atoms apart. (Big RIP)

Theories There are two proposed forms of Dark Energy Cosmological Constant – a constant energy density filling space homogeneously Quintessence – the energy can vary in space and time

Cosmological Constant Has negative pressure equal to its density and causes the universe to accelerate. The reason it has a negative pressure is because energy must be lost (or negative) to do work on an object.

Quintessence In order for dark energy not to clump and come together like matter, it must be extremely light and therefore have a large Compton Wavelength. Compton Wavelength is the wavelength derived from E = mc 2.

Negative Pressure According to the Theory of Relativity, dark energy has strong negative pressure. Negative pressure acts very similar to a force that opposes gravity. This is one of the explanations for why the universe is expanding at an accelerating rate. Accounts for missing mass of universe

Negative Pressure Energy is converted into work done by the vacuum pressure.

Evidence of Dark Energy Accounts for the huge amount of missing mass in the universe. The expansion of the universe is accelerating rather than decelerating. This proves that there is negative pressure since work is being done.