A Look at the Controversies Surrounding Gravity

Newton’s Universal Law of Gravity has been the impetus of many significant advances in physics. Similarly, Einstein’s theories of relativity enabled the creation of a school of science, cosmology, and maintains a symbiotic relationship with the study of quantum mechanics, though quantum gravity proves elusive (“Relativity and the quantum,” n.d.). Einstein’s General Relativity (GR) theory is the accepted standard for modeling gravity, today. Until recently, anyone refuting Einstein was sure to find his or her claim subject to acute skepticism, if not complete dismissal. In fact, controversial claims have been made, and until as late as 2004, one unfortunate observation was made:

Supporters of the big bang theory may retort that these theories do not explain every cosmological observation. But that is scarcely surprising, as their development has been severely hampered by a complete lack of funding. Indeed, such questions and alternatives cannot even now be freely discussed and examined. An open exchange of ideas is lacking in most mainstream conferences. Whereas Richard Feynman could say that “science is the culture of doubt”, in cosmology today doubt and dissent are not tolerated, and young scientists learn to remain silent if they have something negative to say about the standard big bang model. Those who doubt the big bang fear that saying so will cost them their funding. (Alternative Cosmology Group, 2004, para. 5)

Two variant theories have surfaced with promise of becoming accepted, or at least considered: Modified Newtonian Dynamics (MOND) and Tensor-Vector-Scalar (TeVeS). The question remains, will these theories be heard?

Background

Isaac Newton first introduced the concept of gravity in 1686 in his work Principia. Expanding on the ballistics work of Galileo and using the Pythagorean theorem, Newton explained the known observations of the moon’s orbital path around the Earth (Fowler, 2008). This work “led Newton to his famous inverse square law: the force of gravitational attraction between two bodies decreases with increasing distance between them as the inverse of the square of that distance, so if the distance is doubled, the force is down by a factor of four” (“The Moon is Falling,” para. 9) and, hence, extrapolated to the creation of Newton’s Universal Law of Gravity.

Newton’s Universal Law of Gravity states that the force of gravity between two objects is equal to the product of the masses of the two objects divided by the square of the distance between the objects multiplied by the universal gravitational constant. This is a very simplistic explanation of gravity, and though it proves true when considering objects closely related, it fails to explain the observed effects of gravity at both extremely long and intimately short distances (Skordis, 2009 ; Stacey & Tuck, 1981).

Einstein’s work on space-time in the early 1900’s was at odds with the classical notion of gravity. He spent some time reconsidering this impact and devised his GR theory. GR, though expanding the Newtonian law of gravity with the concept of curvatures in space-time to predict the existence of gravitational waves, gravitational lensing, and black holes, according to Skordis (2009), is still lacking and fails to explain the observed distribution of matter throughout the universe. GR requires mathematical adjustment to remain valid in some circumstances, introducing obscure concepts, such as dark energy and dark matter. The combination of dark matter and dark energy is told to comprise more than 95% of all mass in the universe (Filippini, 2005). Yet, this matter has never been observed. This situation presented cosmologists with an opportunity to devise a more complete and elegant solution to explain the effects of gravity. The problem: acceptance.

The Controversy, Itself

“There are significant discrepancies between the visible masses of galaxies and clusters of galaxies and their masses as inferred from Newtonian dynamics” (Sagi & Bekenstein, 2008). Proponents of GR and Newtonian Dynamics present the existence of dark matter and dark energy to provide explanations for these discrepancies. Some researchers did not accept this as a viable solution to the missing mass problem. Instead, they struggled to find a better solution. As earlier researchers presented their work, they were met with arrogance and contempt (Alternative Cosmology Group, 2004). This attitude has dissuaded others from questioning the conventional theories, at least without a sound theory that could hold up to scrutiny.

Modified Newtonian Dynamics (MOND) was probably one of the first contemporary proposals to identify a respectable solution to the quandaries of GR. Though, as Bekenstein and Sanders (2005) describes, it answered the questions of perigalactic gas clouds and some galaxy clustering without the need for dark matter, it failed with its incompatibility to the laws of conservation. The aquadratic lagrangian (AQUAL) theory emerged from MOND to address these shortcomings, though it, too, was flawed as it was a nonrelativistic solution to the problem. Relativistic AQUAL (RAQUAL) was introduced soon after. Being a relativistic version of AQUAL, RAQUAL does not negate AQUAL, and therefore, stays true to the MONDian theory, also. RAQUAL is not without its problems, however, as “it permits superluminal propagation of φ waves (B&M). And it is unable to give an account of gravitational lensing in agreement with the basic observation that lensing by galaxy clusters is anomalously strong compared to what was to be expected in view of their galaxies and gas content” (p. 24). Another problem is that RAQUAL is not covariant and actually “weaken[s] gravitational lensing, rather than enhancing it as intended” (p. 24). The introduction of a constant vector field to the equation both provides a solution and suggests the approach of the Tensor-Vector-Scalar (TeVeS) covariant field theory.

TeVeS is actually a combination of MOND, Newtonian, and Einstein’s GR, with two metrics to interact with the fields in the theory. “Many aspects of TeVeS have been investigated extensively, proving the theory to be faring quite well in view of the huge challenges it was designed to meet” (Sagi, 2009). TeVeS may provide ground-breaking advances in cosmology, and perhaps, in quantum physics.

The controversy surrounding TeVeS and its sound consideration probably stems from the shortcomings of its precursors. This is not a respectable position. Looking through the history of science, rarely is there a major step forward without, first, smaller and error-laden advances. Any new theory that answers real observations should be given an opportunity to mature with greater study and more observational constraint.

Science and Society

This controversy has been raging for the better part of a century. Not until recently has there been a proposed solution that both agrees with GR and Newtonian Dynamics at the same time that it furthers the understanding of gravity where GR fails. Many of the major technological advances in the last century were a direct result of Einstein’s breakthrough contributions to Newtonian physics. One would think that more people would be paying attention, but the general media has not. Perhaps, many of the reporters feel this issue is outside of the realm and scope of their readership’s ability to understand, or maybe, the media just does not realize the import of such discoveries. Unfortunately (or, perhaps, fortunately), the discussion remains technical, equation-laden, and lackluster, helping to keep the influences of the ignorant out of the discussion. Regardless, the limited mainstream coverage limits the controversy to the experts of astrophysics and cosmology.

Society should certainly pay more attention to science; it would serve society well to be an active participant in contemporary scientific discourse. A strong social commitment to science is needed in order to progress responsibly, and though society can prove to be collectively ignorant, it is no marker of overall intelligence. Can society give back to science?

What is (Not) Science?

In a recent Time magazine article (Cray, 2006), Francis Collins, in a debate with Richard Dawkins, attempts to justify his rigor as a scientist with his spiritual beliefs as a Christian. Science is knowledge. Science is neither philosophy nor religion. In the quest for understanding, cosmology is seeking answers to the beginning and hints of the end of time, the self-stated realm of religion. As of this writing, quantum physicists are sifting through anti-matter to glimpse the elusive God particle.

Scientific breakthroughs, though insightful, do not provide testimony against the existence of a Creator, just as uncovering a religious artifact does not negate the latest scientific conclusion. While religion strives to provide an explanation of the beginning of mankind, science is willing to explore the physical boundaries that religion is said to transcend. It would do both camps well to isolate themselves from one another. Cosmology is fraught with opportunity to infringe on religion, especially in the study of gravity. The separation of virtue from knowledge, while allowing them to coexist, is paramount. As we increase our understanding of the macro- and microscopic world around us, especially in the fields of cosmology and quantum physics, the sciences need to maintain a focused and unbiased search for knowledge. This discretion, alone, will limit many of these controversies from arising.

A Changing of the Guard

It appears from the amount of emerging research that there is a renewed vigor among cosmologists to rectify the problems of GR. With the amount of research being submitted to scholarly journals, detractors can no longer deny the need to seriously examine the potential solutions. Additionally, perhaps, the pool of experts have changed, and the conventional mindset has changed with them. Regardless, it appears as though a dearth of research is being completed in the study of universal gravity, and the research is, now, being considered as valid.

This controversy illustrates the need for scientists and field experts to approach emerging solutions with an open mind, though remaining vigilant and skeptical. As a society, we cannot afford having a potential scientific breakthrough remain secreted by virtue of conventionalism, alone. Our knowledge is too important for us to fail in nurturing it.

References

Alternative Cosmology Group. (2004, May 22). Open letter on cosmology. Retrieved from http://www.cosmology.info

Bekenstein, J. D. & Sanders, R. H. (2005). A primer to relativistic MOND theory. In G. Mamon, F. Combes, C. Deffayet & B. Fort (Eds.), EAS Publications Series (Vol. 20, pp. 225-230). doi:10.1051/eas:2006075

Cray, D. (2006, November 5). God vs. science. Time. Retrieved from http://www.time.com

Filippini, J. (2005, August). Why dark matter? Cosmology Group, University of California, Berkley. Retrieved from http://cosmology.berkeley.edu/Education/CosmologyEssays/ Why_Dark_Matter.html

Fowler, M. (2008, November 13). Isaac Newton. Physics Department, University of Virginia. Retrieved from http://galileoandeinstein.physics.virginia.edu/lectures/newton.pdf

Relativity and the quantum. (n.d.). Einstein-Online. Retrieved from http://www.einstein-online.info/en/elementary/quantum/index.html

Sagi, E. (2009, August 15). Preferred frame parameters in the tensor-vector-scalar theory of gravity and its generalization. Physical Review D, 80(4), 44032-44047. doi:10.1103/PhysRevD.80.044032

Sagi, E. & Bekenstein, J. D. (2008, February 1). Black holes in the TeVeS theory of gravity and their thermodynamics. Physical Review D, 77, 024010-024021. doi:10.1103/PhysRevD.77.024010

Skordis, C. (2009, March 21). The Tensor-Vector-Scalar theory and its cosmology. Class.Quant.Grav., 26, 143001-143044. doi:10.1088/0264-9381/26/14/143001

Stacey, F. D. & Tuck, G. J. (1981, July 16). Geophysical evidence for non-newtonian gravity. Nature, 292, 230-232. doi:10.1038/292230a0