Dark secrets of the Universe

Dark secrets of the Universe

It is very common and obvious that we get so much interested in stuffs like the origin of universe and human evolution and always try to think about different possibilities and causes, also our scientists indulge in the same. But, yet, we know very little about how the Universe was created. It’s perhaps likely that we don’t know much– after all, we were never there ourselves,right?. But it’s surprising to realize that when it comes to the ‘Universe at the present time’, we don’t seem to have a much better knowledge of what is out there!! In fact, astronomers and physicists have found that all we see in the Universe – planets, stars, galaxies – accounts for only a small 4% of it! This means, it is not so much the visible things that define the Universe, but rather the void around them.

Cosmological and astrophysical observations indicate that most of the Universe is made up of invisible substances that do not emit electromagnetic radiation – i.e., we cannot detect them directly through telescopes or other similar instruments. We detect them only through their gravitational effects, which makes them very difficult to trace and analyze. These mysterious substances are known as ‘dark matter’ and ‘dark energy’. Their role in the evolution of the Universe is mystery, but within this darkness lays intriguing possibilities of till now undiscovered physics (beyond the established Standard Model).

Dark matter

Dark matter makes up about 23% of the Universe. The first clue of its existence came in 1933, when astronomical observations and calculations of gravitational effects revealed that there must be more ‘stuff (???)' present in the Universe than telescopes couldn’t see.

Researchers now believe that the gravitational effect of dark matter makes galaxies spin faster than expected, and that its gravitational field deviates the light of objects behind it. Measurements of these effects show that dark matter exists, and they can be used to estimate the density of dark matter even though we cannot directly observe it.

But what is dark matter? One idea is that it could contain ‘supersymmetric particles’ i.e. hypothesized particles that are the partners to those already established in the Standard Model.

Dark energy makes up approximately 73% of the Universe and appears to be associated with the vacuum in space. It is homogenously distributed throughout the Universe, not only in space but also in time (what does this mean???,think about it!!!). Meaning -its effect is not weakened as the Universe expands.The even distribution means that dark energy does not have any local gravitational effects, but rather a global effect on the Universe as a whole. This leads to a repulsive force, which tends to accelerate the expansion of the Universe. The rate of expansion and its acceleration can be measured by observations based on the Hubble law. These measurements, together with other scientific data, have confirmed the existence of dark energy and provide an estimate of just how much of this mysterious substance exists.