Cosmological Mile Markers Less Standard than Thought

[Guest_Jim_*]

For any scientific endeavor, you must have accurate measurements because without them a slew of calculations can be thrown off or produce incorrect results. A research team, led by researchers at the University of Arizona, has discovered that certain cosmological measurements are inaccurate, and that our understanding of dark energy may be off.

For a long time it was believed that the size of the Universe was constant, and then it was determined to be expanding, but today we know the expansion is actually accelerating. The exact cause of this acceleration is not known, but has been given the name dark energy. It was discovered by measuring the light emitted by type Ia supernovas, which are explosions of white dwarf stars, throughout the history of the Universe, and comparing their brightness. It has long been believed that this type of supernova is constant and thus always produces the same light, thereby allowing them to act as cosmic candles. What the researchers discovered is that these supernovae are not as constant as believed, as one looks back in time. Instead the researchers found that two distinct populations exist, with those nearer to us being more red than those farther away, from when the Universe was younger.

This discovery was only made possible thanks to the ultraviolet capabilities of the NASA Swift satellite, as the differences in visible light are much more subtle. The researchers found this different both in their own datasets and in others. The exact implications this discovery may have on our understanding of dark energy and astronomy are not yet known and will require a great deal more data to determine.

Source: University of Arizona