Monday, April 13, 2015

Major Systematic Error In Dark Energy Estimates Discovered

It turns out that there are two different subtypes of type 1a supernovas, with one more common in the early universe, and the other more common recently.  They are very hard to distinguish in the visible light spectrum, but have clear differences in the UV spectrum.  As a result, the rate at which the universe is expanding, if indeed it is expanding, and the amount of dark energy in the universe, are systemically overestimated by a significant amount.

Less dark energy may, however, mean that another cosmology mystery is more profound.  This could bring the relative amounts of dark matter and dark energy in the universe closer together, something that is already called the cosmic coincidence problem because there is no obvious theoretical reason for the two dark components of cosmology to be so similar in aggregate amount.


Tienzen said...

Daniel Stolte: "The authors conclude that some of the reported acceleration of the universe can be explained by color differences between the two groups of supernovae, leaving less acceleration than initially reported. This would, in turn, require less dark energy than currently assumed."

The amount dark energy is not calculated via any ‘acceleration’ equation but is derived from CMB data analysis. The conclusion {Major Systematic Error In Dark Energy Estimates Discovered} of that article is mistaken an apple as an orange.

Maju said...

Excuse my ignorance, Tienzen, but what exactly is "CMB data analysis"?

andrew said...

"CMB" is an abbreviation for "cosmic microwave background" which in everyday life is the source of the static you here between radio stations on your radio. These microwaves permeate the universe, helping to bring its average temperature to about two degrees kelvin and are have roots about 13.5 billion years ago, perhaps a few hundred thousand years after the Big Bang around the time that the very first stars ever began to form. They are the oldest scientifically measurable phenomena in the universe and are more than three times as old as planet Earth. They show distinct patterns that can be characterized mathematically with great precision.

Variations in the intensity of CMB from various directions were studied by the Planck satellite and in various earlier studies and this is an important source of experimental data in cosmology.

The CMB data can be reproduced very exactly with a six adjustable parameter formula called the lamdaCDM model also known as the Standard Model of Cosmology (not to be confused with the Standard Model of Particle Physics).

I don't have the time right now to go into the relative importance of CMB v. Type 1a Supernova data in developing dark energy estimates and how those calculations are made, but suffice it to say that both data sets are important sources of experimental data for a wide array of questions in cosmology, and a discovery that a major source of cosmology data that has been used by astronomers and physicists for many decades has a previously unknown major systemic flaw is a big deal no matter which specific results in cosmology are affected.

Maju said...

Thanks for the explanations, Andrew, I was mostly confused by the acronym but what you say is informative anyhow. I'll look into the matter further based on that.

Mitchell said...

Discussion here.