Physics in a Void
Doubts about the existence of "dark energy" have been echoed by Fraser in a Universe Today post. Fraser cites a paper published by Timothy Clifton of Oxford, Living in a Void. Clifton speculates that we could live in a "void" less dense than the surrounding Universe. If so, our region would appear to decelerate slower than distant galaxies, making the Universe appear to accelerate. There would be no need for a hypothetical "dark energy."
Questions about DE have also reached the audience of Amanda Gefter's New Scientist blog.
"Most cosmologists believe that a furtive anti-gravity-like force known as dark energy is to blame...But no one can explain why the observed value of the dark energy is 120 orders of magnitude smaller than what's predicted from quantum physics. In fact, the level of fine-tuning needed to produce such a specifically small but non-zero cosmological constant is so absurd that the best explanation anyone's come up with is that our universe is merely one of an infinite number of universes."
"Scientists shouldn't dismiss ideas just because they might undermine some deeply cherished assumptions...One cosmologist wrote to me in an email: 'There is no fractal or inhomogeneous physical model of the universe of any kind. Therefore although there are particular observations that present a challenge to the standard model, there is no sense in which there is a preferred model that predicts or is explained by inhomogeneity . . . So the observations are interesting, but without a physical model to back them up, they are unlikely to have an impact on our thinking about cosmology.'
"I found this statement rather shocking. Cosmologists are willing to dismiss observations because they don't fit with theory? Isn't science supposed to work the other way round?"
New ideas take a long time to be accepted. Like Ptolemy's epicycles, the "dark energy" hypothesis may take a long time to die. It has produced a divergence of theories to keep physicists employed. Expensive space projects and even trips to Stockholm are dependent on DE existing. Resistance to alternative theories can be expected.
When Earth was believed to be the centre of everything, a divergence of epicycle theories kept academics employed. The Copernican Principle stated that Earth was not the centre, doing away with epicycles. This principle forms a basis of modern cosmology. The hypothesised "dark energy" leads to epicycles not solutions. Before throwing Copernicus away, scientists should consider a changing speed of light.
Labels: dark energy