Revisiting Bohmian mechanics appears to remove the need for a Big Bang


A new way of approaching the way massless particles move in the vacuum of space looks like it has the potential to clean up a number of existing cosmological puzzles – at the cost of changing the way we would understand “time”.


David Bohm (image from Wikimedia)

Ahmed Farag Ali and Saurya Das have published a paper in Physics Reviews vol. B that does all of this and removes the violation of General Relativity that is at the heart of the Big Bang. Essentially what they argue is that we need to revisit David Bohm’s understanding of zero mass particle trajectories. Bohm, a well respected physicist of the last century, found a way of describing a system’s evolution in time that removed the non-deterministic nature of the system. Though Bohmian mechanics is described as a “hidden variable” theory, it’s primary proponent has been J.S. Bell himself (of Bell’s inequality fame). According to Ali and Das, returning to Bohm’s ideas changes the way we understand the beginning and the end of the Universe and essentially gets rid of the conundrum of “dark energy”.

The really provocative claim to my mind is that this new idea allows a direct calculation of the cosmological constant that is in close agreement with what we measure. (Unlike calculations based on the mass energy of the quantum vacuum which are off by many many orders of magnitude, or the handwaving introduction of quintessence.)

From an article on

In addition to not predicting a Big Bang singularity, the new model does not predict a “big crunch” singularity, either. In general relativity, one possible fate of the universe is that it starts to shrink until it collapses in on itself in a big crunch and becomes an infinitely dense point once again.

Ali and Das explain in their paper that their model avoids singularities because of a key difference between classical geodesics and Bohmian trajectories. Classical geodesics eventually cross each other, and the points at which they converge are singularities. In contrast, Bohmian trajectories never cross each other, so singularities do not appear in the equations.

In cosmological terms, the scientists explain that the quantum corrections can be thought of as a cosmological constant term (without the need for dark energy) and a radiation term. These terms keep the universe at a finite size, and therefore give it an infinite age. The terms also make predictions that agree closely with current observations of the cosmological constant and density of the universe.

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