Dark Energy
In 1998 a tiny deviation in the brightness of exploding Stars led Astronomers to conclude that they had no idea what 70% of the Cosmos consists of. All they could say was that space is filled with substance that pushed along the expansion of the Universe rather than holding it back. This substance became known as Dark Energy.
So, just as we were all saying goodbye to the 20th centaury the scientific perception of the Universe was upended. After all the those years of saying that the Universe was slowing down after the Big Bang it was found that the Universe was in fact accelerating.
The big question was;
was the Cosmic acceleration due to Einstein's 'Cosmological Constant', a mysterious form of Dark Energy, or perhaps a lack of understanding of Gravity itself ?
There are plenty of suggestions, but in truth we still don't know the answer.
Theorists say that the pull of Gravity and the push of Dark Energy have been trying to out muscle each other since the beginning of time. About 7 billion years ago, Dark Energy got the upper hand because the Universe had grown so large and matter (the source of Gravity) had expanded and scattered.
Data from Hubble provides supporting evidence that help astrophysicists to understand the nature of Dark Energy. This will allow scientists to begin ruling out some competing explanations that predict that the strength of Dark Energy changes over time.
So, Einstein may have been right after all
there really is a repulsive form of Gravity in space. Einstein first conceived of the notion of a repulsive force in space in his attempt to balance the Universe against the inward pull of its own Gravity, which he thought would ultimately cause the Universe to implode.
His "Cosmological Constant" to represent the possibility that even empty space has energy and couples to Gravity. Like other astronomers of the time, he thought that the Universe was static and so proposed there was a repulsive force from space that kept the Universe in balance.
Einstein discarded his own findings in 1929, when Edwin Hubble found through his research that the Universe was expanding and not static. Today, new data from Hubble may well prove Einstein was on the right track.
It was Dr Adam Riess and the members of the High-z Supernova Team and the Supernova Cosmology Project who used the ground-based telescopes and Hubble to detect the acceleration of the expansion of space from observations of distant supernovae.
Dark Matter
Then there is another unknown called Dark Matter. All the Stars, Galaxies, dust etc that are in the Universe accounts for only 10% of the Universe's mass. This visible stuff is made up of protons, neutrons and electrons and is called ordinary matter. Scientists call ordinary matter 'baryonic matter' because protons and neutrons are subatomic particles called baryons.
The other 90% of the Universe's mass is 'Dark Matter' because it is at hidden and unseen and likely surrounds almost every Galaxy in the known Universe.
Black Holes
Where would Space Fiction be without the Black Hole?
The brilliantly named 'event horizon' added even more mystery to the space movie/TV phenomenon.
But what are Black Holes really?
Here is my incredibly brief explanation:
Black Holes are astronomical objects predicted by Einstein's general relativity. It was thought that due to their strong gravitational effects, space and time are distorted within them, so much so that any matter or even light are imprisoned inside.
The possibility that Stars could collapse to form Black Holes was first theoretically "discovered" in 1939 by J. Robert Oppenheimer and Hartland Snyder, who were manipulating the equations of Einstein's general relativity. The first Black Hole believed to be discovered in the physical world, as opposed to the mathematical world of pencil and paper, was Cygnus X-1, about 7,000 light-years from Earth. Cygnus X-1 was found in 1970. Since then, dozens of Black Hole candidates have been identified. Many astronomers and astrophysicists believe that massive Black Holes, with sizes up to 10 million times that of our Sun, inhabit the centers of energetic Galaxies and Quasars and are responsible for their enormous energy release. Ironically, Einstein himself did not believe in the existence of Black Holes, even though they were predicted by his theory.
In 1974 the British physicist, Stephen Hawking, showed theoretically that Black Holes actually do emit light and particles from its surface, which consequently makes the Black Hole shrink little by little.
Black Holes appear to be intimately connected with the formation of massive spherical bulges in the center of Galaxies. Astronomers have found a direct relationship between the mass of the Black Hole in a Galaxy and the mass of its central bulge. However, the jury is still out on whether small Galaxies contain smaller Black Holes, and their discovery may lead to new insights about the impact of Black Holes on Galaxy formation.
 Contact me at the following :
the.universe.ie@gmail.com
|
