The Search for Gravitational Waves: The BICEP2/Keck Array Project
The understanding of gravity has changed over time since its discovery by the English physicist and mathematician, Isaac Newton, to the current search for gravitational waves. Newton described gravity as a force of attraction that exists between two masses. His law of gravity equates his concept of gravity as a force to the product of a constant (gravitational constant), the two masses, and the inverse of the square of the distance between the centers of the two masses (Grøn and Hervik 256).
Later on, in 1915, Albert Einstein introduced a revolutionary conception of the concept of gravity in his theory of general relativity. He described gravity not as a force, but as a manifestation of the curvature of space-time, where space-time is a fusion of space and time. The theory of relativity postulates that space and time do not exist independently. The main idea in Einstein’s general theory of relativity is that “Matter tells space how to curve; space tells matter how to move” (Einstein: 100 Years of Relativity 75).
In its explanation of the concept of gravity, Einstein’s general theory of relativity predicts the existence of ripples on the space-time curvature, scientifically denoted gravitational waves. Since then, there have been attempts to empirically verify these theoretically predicted waves, as one of the avenues of trying to verify Einstein’s theory as a whole, or r understanding how the universe works. Unfortunately, the waves have “dodged” discovery (if they exist at all). The search for them continues to date, however.
The Most Recent Search for Gravitational Waves: The BICEP2/Keck Array Project
Scientists’ attempts to detect gravitational waves have not been successful. However, this has not encumbered their pursuit. One of the most recent confrontations of the challenge was a 2014 project done jointly by the sister projects Keck Array and BICEP2, both of which were located at the South Pole.
The two projects were intended to measure the remnants of radiation that was emitted shortly after the big bang (which is a theory that postulates that the universe is a product of an expansion, cosmic inflation, from a singularity that began billions of years ago). The radiation is called cosmic microwave background or CMB. Being a form of light, Cosmic Microwave Background exhibits, among other properties of light, the property of polarization. The polarization of cosmic background microwave is a result of being scattered by electrons and atoms. As gravitational waves propagate, they squeeze the space on their paths. Cosmic Microwave Background responds to the perturbations on the curvature of space-time by gravitational waves, thus being forced to take a particular pattern. In other words, gravitational waves ‘curl’ the orientation of the polarization of Cosmic Microwave Background.
The two projects used telescopes to observe the CMB and obtain data from the observation. In their mapping of CMB, Plank focused on the whole sky while Keck Array and BICEP2 concentrated on a small patch of the South Pole sky. The teams’ hunt focused on ‘B-Modes’ polarization, which represents a curling pattern in the orientation of the polarization of cosmic microwave background, the idea being that any detection swirly B-Modes pattern in the polarization in the CMB would be a signature for the existence of gravitational waves. The data obtained was analyzed jointly by the two sister projects for three years in their determination to rule out potential errors. The potential that the pattern observed would be a result of intergalactic dust emission was also put into consideration.
On the 17th of March 2014, Harvard-Smithsonian Center for Astrophysics reported the announcement of the results that were obtained from the analysis of the data and the conclusions drawn from the results. The team was “surprised to detect a B-mode polarization signal considerably stronger than many cosmologists expected” (First Direct Evidence… par. 11). The implication of the results was that cosmic inflation was no longer just a theory-it had taken place, gravitational waves existed and it was a milestone in the understanding of the origin and the mechanism of the universe.
Dispute of the Findings
Earlier, the research teams had mentioned that in their three-year-analysis of the data they had obtained, they had taken into account the possibility that the observed radiation might be emanating from the gas and dust (shining at the same frequency as the CMB) within the Milky Way galaxy. However, a verification of the findings showed that almost all of the results could be explained by the dust in the Milky Way (Gravitational waves … par. 15).
Several explanations of the mistakes that were made were offered: the reliance of the team on the models of emission by galactic dust that were available at the time was the cause of their thinking that the region under observation was free of dust; the collection of data by the two instruments at a single frequency made it difficult to distinguish and separate dust emission from CMB emission; and the precision with which the search could be done was limited by the noise that originates from the instruments.
Conclusion and Comments
Even as the search for gravitational waves continues, the question remains: are they elusive, as things have turned out in the most recent projects or is it simply that they do not exist at all? Ignoring the possibility that research scientists may manipulate data, it is necessary that alternative theories be sought and explored rather than just channeling all the energy to a search whose outcome is uncertain as has it been shown by previous projects and experiments.
“BICEP2 and Planck joint study: Gravitational waves remain elusive.” NSF. 30 Jan. 2015. Web.
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” First Direct Evidence of Cosmic Inflation.” CFA. 17 Mar. 2014. Web. 21
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“Gravitational Waves from Early Universe Remain Elusive” JPL|NASA. 30 Jan. 2015. Web. 21
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Grøn, Øyvind, and Sigbjørn Hervik. Einstein’s General Theory of Relativity: With Modern
Applications in Cosmology. New York: Springer, 2007. Internet resource.