The grand old man of Physics is proved right once again. Albert Einstein was vindicated yet again by a survey, which confirmed the presence of Dark Energy in the Universe. The ‘WiggleZ Dark Energy Survey’ was conducted by 26 astronomers from 14 countries using the latest in spectrograph technologies to map out more than 200,000 galaxies, many halfway across the Universe to confirm this startling fact.
What is Dark Energy?
Dark Energy is the name given to the unknown entity believed to be behind the acceleration of the expansion of the Universe. It was Edwin Hubble, who in 1932, first noticed that the Universe was actually expanding. This gave a huge boost to the Big Bang theory, which says that the Universe came out of an ultra-dense singularity 14-15 billion years ago. Scientists have been expecting the expansion to slow down as time wears on, as then gravity will eventually dominate. What scientists found, instead, was that the Universe was expanding at an ever-increasing rate. It is believed that some mysterious source of energy was aiding the expansion process, thus named Dark Energy.
No one has come up with a proper explanation of Dark Energy, despite there being a number of hypotheses and models. Dark Energy supposedly makes up 73% of the Universe, Dark Matter 23 % (which is NOT the same as Dark Energy; Dark Matter slows down the expansion) and the rest 4% – is ordinary matter – stars, galaxies, nebulae and super-clusters.
Where Einstein fits in…
Einstein had almost predicted the expansion of the Universe in his Theory of General Relativity, but in an uncharacteristic situation in which his nerves weakened, he introduced a factor in his equations which predicted a static Universe. This amounted to including in his equations, a cosmological constant a ‘fudge factor’ which gives vacuum a repelling force, effectively enabling the Universe to counter its own gravity and preventing self-collapse. Later, Einstein would rue this as his ‘greatest blunder’. Now, it seems that the great man was not wrong!
Inflationary theories of modern cosmology use this idea of a cosmological constant to explain the supposed period of rapid expansion right after the Big Bang called inflation. Now, with the increasing rate of expansion, it seems that the cosmological constant was the genius’ masterstroke rather than a botch-up.
The WiggleZ survey
The WiggleZ survey, conducted by an Australian-based group led by Dr. Michael Drinkwater, used the latest in spectrography, thanks to latest Australian technology to survey galaxies more than 200000 of them some 7 billion light years away. Light takes a finite time to travel from one place to another, because of its finite speed. Thus the light from 7 billion light years away took 7 billion years to reach here. This means that we are seeing galaxies in the form they were 7 billion years ago, essentially looking back in time! (Thus, the easiest way to glance into the past is to just see. The farther away the object you see, the farther away in time it is!). The WiggleZ survey can map 392 galaxies in an hour!
Though, this doesn’t tell us the constituents of Dark Energy (or Dark Matter, which is also a mystery), it gives definitive confirmation of its existence. It gives scientists confidence that Einstein’s theory is not failing, and that Dark Energy can indeed be reconciled with General Relativity. The survey is exhaustive measuring both the pattern of distribution of galaxies in the Universe and the rate of formation of the galaxy clusters, essentially giving scientists a two-way confirmatory proof of Dark Energy.
So, there it is again! Einstein is proved right again, and in spectacular fashion. 96% of the stuff in the Universe is unknown, but at least we know that it’s there. Some consolation and a lot of work to be done!