" Dark Fluid " - A Unifying Theory for Dark Matter and Dark Energy by Jamies Farnes

A new model suggests Dark Matter and Dark Energy unify into a fluid with ' negative mass '

Can a simple minus sign may solve one of the longest standing problems in Physics ? These were the words of Jamie Farnes when he published his theory on The Dark Fluid and by the end of this blog, you might also think the same. Dark Energy and Dark Matter are the invisible theoretical substances that are thought to make up nearly 95% of the Universe, but their existence is only theorised, based on the effects they appear to have on the observable matter we're all familiar with. Some of the most technical and sensitive instruments ever made by humans have failed to detect any sign of the stuff after nearly 50 years of searching. But, a new theory proposed by a scientist at the University of Oxford claims to explain the missing 95 percent of the cosmos - the matter that physicists can't yet definitively account for. 
 

The solution to one of the most intractable mysteries faced by the modern physics might be found in one of Albert Einstein's forgotten theories that the famous physicist abandoned nearly a century ago. So, this quest took us back to the time of 19th century when Albert Einstein published his Theory of Relativity. As a paper published recently, talks about the theory developed by Albert Einstein in 1918 and which was further abandoned by Einstein himself, may have held the key to the mystery of Dark Matter and Dark Energy all along. Oxford Astrophysicist Jamie Farnes drew on his theory, to come up with a new theory that unifies Dark Matter and Dark Energy as a single " Dark Fluid " that permeates the Universe. Farnes theory has its roots in a small note Einstein made to himself in 1918 while he was struggling with the cosmological constant - which Einstein first used to describe the dynamics of the Universe in his equations of general relativity.

Here /\ is the Cosmological Constant

Einstein invoked the cosmological constant to explain the static nature of the Universe, which was widely accepted at that time, while also accounting for the effects of gravity. Without this cosmological constant Einstein realised that the gravitational force of the universe would cause it to collapse upon itself. Basically this cosmological constant was a term that functioned as a sort of anti-gravity. The problem for Einstein was to explain what this cosmological constant consisted of. So, in 1918 Einstein described a modification of general relativity where empty space takes the role of gravitating negative masses which are distributed all over the interstellar space, the key phrase here was the - " negative mass ".

By the following year, however Einstein have adopted several different interpretation of the cosmological constant and this small note was lost to history. In 1931 Einstein removed the cosmological constant from his theory of General Relativity after Edward Hubble discovered that the Universe was expanding with respect to time. This phenomenal observational evidence led Einstein to describe his invocation of the cosmological constant as his greatest blunder. Today however, Einstein's cosmological constant is hardly believed as a blunder by most of the physicist all across the globe.

Infact, the cosmological constant is integral to the Lambda-CDM Model, the most widely accepted model of the Universe. In this model of the Universe the cosmological constant represents Dark Energy, which is invoked to explain the accelerating expansion of the Universe. The Lambda-CDM model also invokes to explain Dark Matter as a way to explain the observed galactic rotation. The gravitational influence on the stars on the outskirts of the galaxy is less than the gravitational influence on the stars at the centre of the galaxy, which suggests that the stars on the outskirts of the galaxy should be rotating much more faster than the inner stars. Infact, galaxies must be flying apart from each other due to their own rotational force. So, Dark Matter is theorised as the stuff that keeps galaxies intact and accounts for the observed rotational speed of the stars. Yet in the past half century, dozens of experiments meant to detect Dark Matter and Dark Energy have come away empty-handed.

Farnes new theory is a radical departure, but if it's correct it would fundamentally change our understanding of the Universe. This Dark Fluid, if it exists, have negative mass. Unlike normal matter positive gravitational charge or mass (means it attracts other matter), negative mass would repel matter. In sort, if you pushed an object that has negative mass away from you, then the object will move towards you rather than moving in the direction of the applied force. According to Farnes negative masses would be spread throughout the Universe as a single substance in the form of Dark Fluid. So, Dark Matter and Dark Energy can be unified into a single substance, with both being simply explainable as positive mass matter surfing on a sea of negative masses. Farnes new theory is both elegant and intuitive after all he point's out in his paper - polarisation, things simply existing in positive and negative forms is a common property in the Universe. There are positive and negative electrical charges, and even information itself appears to be polarised in the forms of zero's and one's . It would be odd if such a fundamental property as mass has monopolised positive charges only. 

Some earlier studies have ruled out the existence of negative matter on the basis that it would become less dense during the expansion of the Universe, which runs contrary to the observations demonstrating that Dark Energy doesn't dilute with respect to time. However, Farnes theory of negative matter applies a 'creation tensor', which allows for continuous creation of negative masses. It shows that when more negative masses come into existence, the negative mass fluid does not become less dense during the expansion of the Universe, and appears to be identical to Dark Energy. Farnes research also features a computer simulation which correctly predicts the formation and behaviour of Dark Matter halos, just like the ones inferred by observations via advanced radio telescopes.

This new theory generates a wealth of new questions. As with all other scientific theories the adventure doesn't ends up here. Infact the quest to understand the nature of our Universe has only just begun !