Introduction
Gravity is one of the key forces of Nature and is basically the first force of nature to be studied in the earlier centuries. It was Einstein who initially came up with the first law of gravity, that is, Einstein’s gravitational field equation. The equation hypothesizes the rule of proportionality and the principle of general relativity (Holcomb and Hawley 105). The general relativity principle demands that the gravitational law be autonomous of direction changes, and controls the functionality of Einstein’s equation. The Einstein gravitational field equation originates from the Langrangian dynamics principle (Hernandez, Ma and Wang 6).
Dark matter and dark energy are two critical wonders that require additional study of the gravitational law. As of late, it appears that the existence of dark matter and dark energy infers that the variation of the Einstein-Hilbert functional should fall under energy-momentum protection control, which is commonly known as the interaction dynamics principle (Baldi 22). Interaction dynamics principle is derived from the following gravitational field equations:
……………… (1)
The equation is appended by the following energy-momentum conservation equation:
………………………….. (2)
According to astrophysics, dark matter is an unfamiliar form of matter that only takes part in the gravitational interactions, but do not discharge nor take in electromagnetic radiations (Baldi 22). Dark matter was initially hypothesized by Jan Oort, an astronomer from Holland, in the early 1930s. Jan Oort established that the orbital speed of stars in the Milky Way did not correspond to their masses. The dark matter theory is hugely backed by the Rubin gyratory arcs for galaxy gyratory speed.
The galaxy’s rotational curve is the gyratory speed of discernible stars or gasses in the galactic cycle based on their outspread distance from the midpoint. This amounts to saying that nearly all the stars in the galactic cycle move at approximately the same velocity. The Rubin rotational curve goes against the conventional logic where rotational speed is dictated by radial distance. For this reason, the Rubin curve confirms the existence of an extra gravitational effect to gravity by the discernable matter in the galactic cycle (Turner 44).
Astrophysical studies have exposed inconsistencies between the mass determined from the gravitational effect and the mass computed from the discernible matter. The omitted mass proves the existence of dark matter in space (Holcomb and Hawley 163). The new gravitational force formula shows that the dark matter is a space curved-energy. This energy is equal to a gravitational effect, hence the term “dark energy”. This term was primarily introduced in the 1990s and was pegged on the notion that the universe is expanding. A report published by the top planetary explorers in the U.S. shows discrepancies between the computed and hypothetical information regarding the acceleration of the expanding universe. These discrepancies are explained using Hubble Law and Friedman’s theory. The accelerating expansion is generally recognized as proof of the presence of dark energy (Springel par.8.).
Contemporary studies and developments on dark matter and dark energy
Nature and the characteristics of dark matter and dark comprise one of the main challenges in contemporary astrophysics and science as a whole. Whereas the proof for their presence at the moment appears irrefutable after more than a decade of experiments and planetary studies, all recognizing the need to come up with new models for the two enigmatic phenomena, their essential nature remains anonymous. Nevertheless, numerous efforts are being made to uncover the mystery behind the two components and to help explain the “dark segment” that controls the universal energy density (Springel par.1.).
The advanced satellite observatories, for instance, WMAP and Plank have progressively enhanced our understanding of different components of the universe. In accordance with the latest measures of the composition of the universe, only 5 percent constitute “normal matter”, 27 percent comprised of “dark matter” and 68 percent is made up of even “darker matter”. The complementary ground observatories have mapped the locations of space objects and galactic components.
The dark matter occupies the largest volume (Royal Astronomical Society par.1.). According to the Royal Astronomical Society, nearly half of the whole mass of the universe is in the galaxy (par. 3.). This mass has been compressed into a volume of 0.2 percent of discernable matter while an additional 44 percent is absorbed in the enclosing filament. Merely 6 percent is present in voids and constitute 80 percent of the bulk (Royal Astronomical Society par.3.).
So far, the dark matter has not been seen at a close range. This is due to the fact that it does not interact with heavy elementary particles and is entirely undetectable using light. This makes the dark matter difficult to detect using contemporary instruments. However, the astrophysicists are assertive of its presence due to its gravitational effects on galaxies and its clusters (Springel par.4.). As per the standard physics, stars that are far away from the galactic center should be slower than those near the galactic center. But recent observations using the state-of-the-art instruments have shown that all the stars travel at almost the same speed irrespective of their radial distance. This mystifying observation makes sense when it is presumed that the stars far away from the galactic center are experiencing the gravitational effect of an invisible mass (Springel par.5.).
Dark matter describes some visual impressions that astrophysicists usually see in the distant space. The galaxies are normally pictured to have peculiar rings and sweeps of light. In the more distant galaxies, the pictures are more distorted and augmented by the indiscernible cloud of dark matter. This phenomenon is commonly referred to as gravitational lensing (Springel par.5.). Hernandez, Ma, and Wang affirm that dark matter is made up of foreign particles that do not intermingle with the regular matter or electromagnetic spectrum but still wield a gravitational pull (8).
As already been mentioned, the universe keeps on expanding at an accelerated rate despite the attractive force of gravity. Scientists attribute this to a type of aversive force produced by quantum variations in the “void” space. Furthermore, this force appears to be increasing as the universe expands. Since the scientist did not have a better name for this repulsive force, they called it “dark energy” (Turner 5). Dark energy is more mysterious than dark matter since there is no conventional explanation regarding it. Some scientists believe that dark energy is one of the five quintessence forces, which were previously unknown. The quintessence forces fill the universe similar to a fluid. However, many scientists point out that the recognized features of dark energy are in line with the cosmological constant. The cosmological constant is a mathematical Band-Aid that was introduced by Albert Einstein when formulating his theory of relativity (Springel par.7.).
Einstein used cosmological constant to make his model fit the concept of the motionless universe. He believed that there was an aversive force that countered gravitational pull and helped in preventing the universe from collapsing. Einstein’s idea was later rejected when the advanced satellite observatories showed that that the universe was expanding. In fact, most scientists consider this as Einstein’s biggest blunder (Springel par.9.).
A recent study carried out by Baldi shows how dark matter and dark energy openly correlate with each other by swapping energy during their galactic revolution (134). He presented dark energy as a dynamical mass substituting the galactic constant of the conventional models and in a phenomenological depiction, explains the relation between dark energy and dark matter liquid. His study relied on a huge number of literature linked to dark matter and dark energy interactions. The study disapproves of some of the previous studies that postulated an upsurge in concentration and density profiles at the galactic center than in the galactic edge (Baldi 135).
Conclusion
As much as scientists have tried to explain the existence of the two universal components, a lot still needs to be done. Advanced satellite observatories like WMAP and Plank have progressively enhanced our understanding of the two components. However, since the two components cannot interact with normal matter and light, they have made the work of scientists more difficult. Nonetheless, astrophysicists are assertive of their presence due to their gravitational effects on galaxies and their clusters. The discrepancies between the computed and theoretical data as regards the acceleration of the expanding universe explained using Hubble Law and Friedman’s theory also helps us to prove the presence of dark matter and dark energy.
Works Cited
Baldi, Marco. Interactions between dark energy and dark matter, Munich: der Ludwig-Maximilian University, 2009. Print.
Hernandez, Marco, Tian Ma and Shouhong Wang. “Theory of Dark Energy and Dark Matter.” Journal of Mathematical Study 48. 3 (2015):199-221. Print.
Holcomb, Katherine and John Hawley. Foundation of Modern Cosmology. 2nd ed. Oxford: Oxford University Press, 2005. Print.
Royal Astronomical Society. Black holes banish matter into cosmic voids. 2016. Web.
Springel, Volker. Dark Matter and Dark Energy. 2016. Web.
Turner, Michael. Dark Energy and the New Cosmology, Chicago, IL: University of Chicago, 2003. Print.