Search results
Results From The WOW.Com Content Network
Phantom energy is a hypothetical form of dark energy satisfying the equation of state = with <. It possesses negative kinetic energy , and predicts expansion of the universe in excess of that predicted by a cosmological constant , which leads to a Big Rip .
In physics, quintessence is a hypothetical form of dark energy, more precisely a scalar field minimally coupled to gravity, postulated as an explanation of the observation of an accelerating rate of expansion of the universe. The first example of this scenario was proposed by Ratra and Peebles (1988) [1] and Wetterich (1988).
This phantom was the most complex model to date, with over 3.7 billion voxels. This model was used in many studies concerning health physics and medical physics. Dr. Bolch and team at the University of Florida created a set of pediatric phantoms from 2002 to 2006. [17] Child computational phantoms had been severely underrepresented until this ...
The cosmological constant was originally introduced in Einstein's 1917 paper entitled “The cosmological considerations in the General Theory of Reality”. [2] Einstein included the cosmological constant as a term in his field equations for general relativity because he was dissatisfied that otherwise his equations did not allow for a static universe: gravity would cause a universe that was ...
Robert R. Caldwell is an American theoretical physicist and professor of physics and astronomy at Dartmouth College. His research interests include cosmology and gravitation . [ 2 ] He is known primarily for his work on theories of cosmic acceleration , [ 3 ] in particular dark energy , quintessence , [ 4 ] and the Big Rip scenario.
In physical cosmology, the Big Rip is a hypothetical cosmological model concerning the ultimate fate of the universe, in which the matter of the universe, from stars and galaxies to atoms and subatomic particles, and even spacetime itself, is progressively torn apart by the expansion of the universe at a certain time in the future, until distances between particles will infinitely increase.
The following is a list of notable unsolved problems grouped into broad areas of physics. [1]Some of the major unsolved problems in physics are theoretical, meaning that existing theories seem incapable of explaining a certain observed phenomenon or experimental result.
(more unsolved problems in physics) In cosmology , the cosmological constant problem or vacuum catastrophe is the substantial disagreement between the observed values of vacuum energy density (the small value of the cosmological constant ) and the much larger theoretical value of zero-point energy suggested by quantum field theory .