The standard cosmological model known as LambdaCDM can only explain 5% of the observable Universe. The remaining 95% is famously made up almost entirely of two invisible components called dark matter and dark energy. Yet the physical nature of these two components remains a mystery. A new study by University of Oxford researcher Jamie Farnes suggests both dark phenomena can be unified into a single substance — a negative-mass ‘dark fluid.’ Dr. Farnes’ theory may also prove right a prediction that Albert Einstein made 100 years ago.
“I think that both dark matter and dark energy can be unified into a fluid which possesses a type of ‘negative gravity,’ repelling all other material around them,” Dr. Farnes said.
“Although this matter is peculiar to us, it suggests that our cosmos is symmetrical in both positive and negative qualities.”
The existence of negative matter had previously been ruled out as it was thought this material would become less dense as the Universe expands, which runs contrary to our observations that show dark energy does not thin out over time.
However, Dr. Farnes’ theory applies a ‘creation tensor,’ which allows for negative masses to be continuously created.
It demonstrates that when more and more negative masses are continually bursting into existence, this negative mass fluid does not dilute during the expansion of the cosmos. In fact, the fluid appears to be identical to dark energy.
The new theory also provides the first correct predictions of the behavior of dark matter halos.
Most galaxies are rotating so rapidly they should be tearing themselves apart, which suggests that an invisible ‘halo’ of dark matter must be holding them together.
Dr. Farnes’ study features a computer simulation of the properties of negative mass, which predicts the formation of dark matter halos just like the ones inferred by observations using modern radio telescopes.
Albert Einstein provided the first hint of the dark Universe exactly 100 years ago, when he discovered a parameter in his equations known as the ‘cosmological constant,’ which we now know to be synonymous with dark energy.
Einstein famously called the cosmological constant his ‘biggest blunder,’ although modern astrophysical observations prove that it is a real phenomenon.
In notes dating back to 1918, Einstein described his cosmological constant, writing that ‘a modification of the theory is required such that ‘empty space’ takes the role of gravitating negative masses which are distributed all over the interstellar space.’ It is therefore possible that Einstein himself predicted a negative-mass-filled Universe.
“Previous approaches to combining dark energy and dark matter have attempted to modify Einstein’s theory of general relativity, which has turned out to be incredibly challenging,” Dr. Farnes said.
“The new approach takes two old ideas that are known to be compatible with Einstein’s theory — negative masses and matter creation — and combines them together.”
“The outcome seems rather beautiful: dark energy and dark matter can be unified into a single substance, with both effects being simply explainable as positive mass matter surfing on a sea of negative masses.”
J.S. Farnes et al. 2018. A unifying theory of dark energy and dark matter: Negative masses and matter creation within a modified ΛCDM framework. AA 620, A92; doi: 10.1051/0004-6361/201832898