By HARRISON SCHWARZER
GUEST WRITER
In a joint analysis from the European Space Agency (ESA) and BICEP2, astronomers have announced last year’s purported observation of primordial gravitational waves, echoes of the Big Bang, were no more than shadows of galactic dust. Said cosmologist Marc Kamionkowski of John Hopkin’s to Nature.com, “I no longer believe that BICEP2 detected the signal of gravitational waves.”
In March of 2014, the team of researcher’s at the South Pole’s BICEP2 radio telescope claimed to have detected polarized microwaves from the Cosmic Background Radiation. These results were shocking- they indicated that the theory of Cosmic Inflation, widely held to be true for its explanatory capabilities, but as-of-then untested, was a verifiable, empirical fact. In the short time after the Big Bang, around the order of one-trillionth of one-trillionth of one-trillionth of the first second that ever was, the universe expanded from about the size of a proton to that of a grapefruit. This expansion, hypothesized by Alan Guth in 1981, is critical to our understanding of the known universe.
No matter which direction we look from the earth, a faint glow of light can be observed. This light, known as the Cosmic Background Radiation, is considered to be an imprint of the Big Bang on the sky, a snapshot of the early universe. It is the window through which physicists can look back in time to hypothesize our cosmological origins. But until 1981, the uniformity, or smoothness, of the CBR was unexplained. The CBR was thought to be too large any two points to be “causally connected”, a fancy physics word for “touching”.
Another way of phrasing the problem of the CBR is this: light travels at a fixed speed, and that speed is the fastest anything can go. Then, the universe being 13.8 billion years old, it must have a radius of 13.8 billion light years. But this isn’t the case: the observable universe about the Earth is 45 billion light years alone. How can this be if nothing can go faster than light? The answer is that light propagates through space itself, and the pace of that propagation is fixed. But the space through which light propagates can move at whatever speed it likes, pulling whatever it encloses with it. So at some point the whole of the Cosmic Background Radiation was a very-nearly uniform blob, and then exploded outwards during this period of inflation. This inflation was so violent that it left ripples in light itself, primordial gravitational waves, the same ripples BICEP2 believed it found.
Unfortunately for the BICEP2 team, the signals they detected in the Cosmic Background Radiation are so similar to those caused simply by the dust that floats through empty space that the two cannot be distinguished. According to the ESA, BICEP2 jumped the gun in reporting its results, failing to account adequately for this effect. The theory of Cosmic Inflation is far from abandoned, but researchers are back to square one.
Researcher George Efstathiou downplayed this result to Nature.com, saying, “I don’t know why people are so excited. There’s nothing dramatic here from the science point of view.”