Normally, fluid dynamics and cosmology are widely separate disciplines. Problems like the flow of water through a pipe have little to do with the evolution and fate of the universe; but, as it turns out, if one allow fluids to move near the speed of light, one will find some interesting properties that might have cosmological implications.
Collaborating with physicists Thomas Kephart and Robert Scherrer, mathematician Marcelo Disconzi recently published his findings in the fairly esoteric field of relativistic fluid dynamics — the science of fluids moving near the speed of light. Specifically, Disconzi created a new mathematical formulation of bulk viscosity, a measure of a fluid’s resistance to expansion or contraction (1, 2). Other formulations of relativistic bulk viscosity allow signals in a fluid to travel faster than the speed of light— a property that flies in the face of special relativity and cannot be allowed in any physical situation. Disconzi’s new mathematics avoids this problem (2).
Disconzi’s new ideas about bulk viscosity could have cosmological implications. If one treats the universe and everything in it as an enormous fluid, relativistic fluid dynamics can yield insight into the behavior of the universe. The new formulation of bulk viscosity might help explain dark energy — the unknown force behind the accelerating expansion of the universe. In particular, it seems to allow for the “Big Rip,” one possible fate of the universe (1).
The physics is complicated, but the Big Rip occurs when dark energy grows so strong and the universe expands so quickly that every single object in the universe, down to the atomic level, is driven apart, leaving nothing but elementary particles and radiation. While other cosmological theories do not allow this scenario, Disconzi’s new math does (1).
Much more work must be done to determine whether the new mathematics of relativistic bulk viscosity actually has cosmological implications. Nonetheless, this discovery helps connect two seemingly disparate fields of science and provides a starting point for new routes of scientific exploration.
- Disconzi, M. M., Kephart, T. W. & Scherrer, R. J. (2015). New approach to cosmological bulk viscosity. Physical Review D (91).
- Salisbury, D. (2015, June 30). New model of cosmic stickiness favors ‘Big Rip’ demise of universe. Retreived from http://www.sciencedaily.com/releases/2015/06/150630155221.htm