What is Dark Energy ? Is it energy derived from the Devil ? No, absolutely not. While I would love to tell you about what dark energy really is, unfortunately that is still unknown (If you do find out, do tell us, and maybe you can win a Nobel Prize on the way). If we do not know what we are looking for, how can we be certain it exists ?
To understand dark energy we first need to examine our own universe and fundamental forces in action. We know that the Universe is expanding, see previous blogs for explanations, and we also know that gravity attracts objects, that’s why your feet are firmly planted on the ground. Take a second to understand that, our universe is expanding but gravity pulls objects together. Given the extreme amounts of matter within the universe, gravity should pull objects together and the universe should definitely not be expanding ? While Edwin Hubble discovered that the universe was expanding in 1920’s, most scientists thought gravity would slow down the rate of expansion or even start contracting the galaxy. However in 1998 Schmidt and Reiss(2011 Nobel Laureates) found the rate of expansion to actually be increasing. This meant that there has to be another form of energy driving this expansion, otherwise gravity would at least slow down the rate of expansion.
The increase in the rate of expansion of the universe coupled with the known effects of gravity in itself prove the existence of an unknown energy(dark energy). However we can also look at the cosmic microwave background.
The cosmic microwave background is leftover radiation from the early universe, remnants of the big bang. We know that dark energy pushes away matter(why our the rate of expansion is increasing), thus for the cosmic radiation to be even throughout the cosmic microwave background there needs to be a lot of dark energy. Therefore since we can observe a constant cosmic microwave background we know that there needs to be a lot of dark matter to repel matter evenly across the universe.
As scientists it is important to use different methods to independently verify results, as each method might have its own problems. The graph below shows our estimates for the amount of dark energy and dark matter by putting three of independent verifications of dark energy together to find an estimate of the amount of dark energy in the universe.
Citations:
Cain, Fraiser. "How Do We Know Dark Energy Exists? - Universe Today." Universe Today. N.p., 23 Dec. 2015. Web. 09 Dec. 2016.
"The Expanding Universe." The Expanding Universe. Sloan Foundation, n.d. Web. 09 Dec. 2016.
"Dark Energy Is Real, Study Says." Space.com. Space.com, 12 Sept. 2016. Web. 09 Dec. 2016.
Stuart, Colin. "Dark Energy Spotted in the Cosmic Microwave Background." Physics World. Institute of Physics, 15 July 2011. Web. 9 Dec. 2016.
Carroll, Sean. "Why Does Dark Energy Make the Universe Accelerate?" Preposterous Universe. N.p., 16 Nov. 2013. Web. 09 Dec. 2016.
Images:
No comments:
Post a Comment