Emergent Gravity Theory Challenging General Relativity

The general theory of relativity by Einstein was published in 1915, it was hailed as one of the biggest masterpieces in physics, explaining the motion of stars and galaxies, and the matter-energy equivalence and the curving of space-time. But this theory shows some discrepancies at large scales. The value of gravity calculated from the general theory of relativity is different from the observed value. The reason, scientists think, is dark matter, a hypothetical, non-interacting form of matter that hasn’t been detected yet. Do not confuse dark matter with dark energy. The latter is the energy of ’empty space’, and has been observed and is very real. A lot of research and money has been dedicated towards detecting these ‘invisible’ dark matter particles, but all in vain. This is why, now many scientists are finding alternative explanations.

According to general relativity, the curve of space-time due to matter and energy is the cause of gravitational force

One such scientist is Erik Verlinde, from University of Amsterdam and the Delta Institute of Theoretical Physics. He is a string theorist, who has published a paper, explaining his new theory, which doesn’t require the existence of dark matter. Verlinde argues that gravity is not a force as believed till now, instead it is an ’emergent phenomenon’. This gravity he called ’emergent gravity’ or ‘entropy gravity’. His paper has a lot of higher level physics in it, but the basic idea is that the resultant distribution of gravity in the Universe is due to matter-energy, dark energy, and entropy. He uses the concepts of quantum information, thermodynamics, black hole physics and string theory. He argues that in order to attain maximum entropy, which also means more stability, the system has an entropic force subject to quantum disorders, which does not result from fundamental interactions. This is favourable in higher dimensions, and though this energy is uniform in large-scale, it is affected by the ‘jitters’ in the quantum realm.

erik verlinde
Erik Verlinde: Pioneer of The Theory Of Emergent Gravity

This energy of entropy results from the quantum entanglement of spacetime bits of information. Remember that entropy, is itself a measure of information content and the level of disorder in a system. The theory of entropic gravity posits that what has been interpreted as unobserved dark matter is actually the product of quantum effects that can be regarded as a form of positive dark energy that lifts the vacuum energy of space from its ground state value.

His theory can be proven wrong by finding a dark matter particle, and can be proven through observations. The crazy part is, Leiden Observatory, after observing 33,000 galaxies, found that Verlinde’s theory explained the distribution of gravity better and more accurately than Einstein’s relativity.

“Many theoretical physicists like me are working on a revision of the theory, and some major advancements have been made. We might be standing on the brink of a new scientific revolution that will radically change our views on the very nature of space, time and gravity,” – Erik Verlinde, University of Amsterdam

If confirmed, his theory will bring a revolution, and turn over the tables completely. One of the most important theories of physics-Relativity will have to be abandoned, and all that we know has to be modified. But, even then, his theory will go through improvements, and changes as more scientists will work on it. The theory as of now only applies to isolated, spherical, and static systems. Also, a specific microscopic model has been proposed that indeed leads to entropic gravity emerging at large scales. Archil Kobakhidze at The University of Melbourne on the other hand showed that the predictions made about the behaviour of quantum particles like neutrons under gravity by the traditional theory of gravity as a force (relativity) and theory of emergent gravity are different, and experiments show that behaviour of neutrons is same as predicted by relativity. So, what is the truth? Leidein Observatory’s research or The behaviour of neutron under gravity?  Physicists have chosen sides, and the stakes are incredibly high, let’s see who explains the Universe better. Happy Reading!

-The Cosmogasmic Person


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