|Date||March 22, 2019||Time||3:35 - 5:00 pm|
|Location||Baylor Sciences Building, Room E.125|
New Wormhole Solution in de Sitter Space
In 1935 the original wormhole solution was discovered by Einstein and Rosen (ER), but it wasnt until the recent ER=EPR conjecture proposed in 2013 that predicts that Einsteins, spooky interaction at a distance, known as quantum entanglement, could possibly be explained by instantaneous communication through a wormhole. Most wormhole solutions describe two points separated by infinite distance (usually interpreted as a different universe) allowing instantaneous communication while forbidding communication outside of the wormhole. This new paper presents a new exact solution to vacuum Einstein’s equations describing a wormhole connecting two causally connected points of the same universe separated by finite distance, so that any two points outside the wormhole may communicate with each other. The new solution proposed, is obtained by placing two black holes at the antipodes of closed de Sitter space with a matter shell between them. The authors work in de Sitter space endowed with positive vacuum energy density (cosmological constant), which produces a repulsive force that could balance the gravitational attraction of two black holes, analogous to creating a static configuration by assigning some charge to the black holes to counteract gravity. The resulting global topology of the spacetime metric is that of a torus. Since the universe is static, signals may causally propagate from one black hole to the other across the equator, however, the wormhole is non-traversable due to the existence of the black hole horizon.
Dai, De-Chang, etal. New Wormhole Solution in De Sitter Space. Physical Review D, vol. 98, no. 12, 2018, doi:10.1103/physrevd.98.124026.
How I Learned to Stop Worrying and Love Negative Mass
In the 30 or so years since the dark energy/cold dark matter (ΛCDM) was first proposed there is still no strong agreement about the physical origin of dark energy or the true nature of dark matter. In this talk, we will consider an often-neglected possibility: that dark matter and dark energy could in fact be composed of particles with negative inertial and gravitational mass. Such negative mass matter is known to be fully consistent with Newtonian mechanics and general relativity. Initial results from this toy model simulations demonstrate the ability of this framework to fix galactic rotation curves, without the formation of cuspy halos typical of positive mass models. These simulations also show that negative mass can allow for the formation of large-scale structure with appropriate filaments and voids. A review of observation data also provides hints that this model may be much more consistent with what we know about our universe than once thought.
A unifying theory of dark energy and dark matter: Negative masses and matter creation within a modified ΛCDM framework, J. S. Farnes, A&A 620 A92 (2018), DOI: 10.1051/0004-6361/201832898
|Publisher||Department of Physics|
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