The astronomers who earlier this year announced that they had
evidence of primordial gravitational waves jumped the gun, two independent
analyses suggest.
The papers, published on the arXiv preprint repository, propose
that the original analysis did not properly account for the confounding effects
of galactic dust. Although further observations may yet confirm the findings,
independent researchers now say they no longer think that the original data
constituted significant evidence.
"Based on what we
know right now, we have no evidence for or against gravitational waves," says
Uros Seljak, a cosmologist at the University of California, Berkeley, and
co-author of one of the latest studies.
Astronomers using the BICEP2 radio teleÂscope at the South Pole
announced in March that they had found a faint twisting pattern in the
polarization of the cosmic microwave background (CMB), the radiation left over
from the Big Bang. This pattern, they said, was evidence for primordial
gravitational waves ripples in the fabric of space-time generated in the
Universe's first moments. The findings were widely hailed as confirmation of
the theory of cosmic inflation, which holds that the cosmos ballooned in size
during the first fraction of a second after the Big Bang.
But the new analyses
suggest that the twisting patterns in the CMB polarization could just as easily
beaccounted for by dust in
the Milky Way.
The papers follow a presentation three weeks ago by Raphael
Flauger, a theoretical physicist at New York University and the Institute for
Advanced Study in Princeton, who re-examined a map of galactic dust used by
BICEP2. Flauger concluded that the BICEP2 researchers had probably
underestimated the fraction of polarization caused by dust in the map, which
was compiled from data from the European Space Agency's Planck spacecraft.
Flauger says that when the dust is fully accounted for, the signal that can be attributed
to gravitational waves either vanishes or is greatly diminished.
"I had thought that the [BICEP2] result was very
secure," said Alan Guth, the cosmologist who first proposed the inflation
concept in 1980, after learning about Flauger's talk. "Now the situation
has changed," added Guth, who works at the Massachusetts Institute of
Technology in Cambridge.
The BICEP2 researchers have argued that the Planck map figured
in only one of the six models that they used to examine the role of dust. But
in a paper posted to the arXiv server on 28 May, Flauger and his co-authors
David Spergel and Colin Hill, both of Princeton University in New Jersey, say
that the five other models are based on a low estimate between 3.5% and 5% of
the fraction of total polarization caused by galactic dust. Extrapolation from
a more detailed map, released last month by the Planck team, suggests that the
fraction is closer to 815%, Spergel explains.
With those updated numbers, he says,there's no evidence for the
detection of gravitational waves. But a final determination cannot be made
until a more precise dust map, expected to be released by the Planck team in
October, is available, he adds.
In the other analysis, Seljak and Michael Mortonson, a
cosmologist also at the University of California, Berkeley, re-examined BICEP2
data on how the polarization signal varies with the frequency of the microwaves
it detects. The BICEP2 team had checked its results against data recorded at
lower frequency by an older telescope, BICEP1. They found that the intensity of
polarization did not change from one frequency to the other in the way expected
if it were caused by dust, and concluded that the data favoured gravitational
waves over dust by an 11-to-1 margin.
But Seljak and Mortonson say that the BICEP2 analysis did not
exclude data on small spatial scales, or fractions of degrees of the sky. That
is a problem, Seljak says, because on these small scales, gravitational lensing
in which the path of light bends around massive objects exactly mimics the
twisting polarization pattern that gravitational waves imprint on larger
spatial scales.
Accounting for lensing,the primordial gravity-wave signal is
preferred to dust with odds of less than two to one in other words, not
significant odds at all, says Seljak.
BICEP2 co-leader James Bock, a physicist at the California
Institute of Technology in Pasadena, says that although his group's main paper
has been revised based on many referee comments and resubmitted for
publication, the evidence for gravitational waves is certainly not being
retracted. The BICEP2 results are basically unchanged, he says.
Further observations may yet see the cosmic ripples emerge from
the dust. It is possible that forthcoming data from several observatories
including the Keck Array, a telescope at the South Pole built by the BICEP2
teamand the Planck team's full-sky map of CMB polarization will confirm that a
signal is there, although perhaps not as strong as first suggested.
This story originally appeared in Nature News.
The article below has been refuted, although my Simple Explanation cosmology is unaffected by the news. So you can skip this part of the original article if you want to and go to the Simple Explanation at the end.
I'm pretty excited about this new gravitational wave discovery. On St. Patrick's Day, astronomers working from an observatory at the earth's South Pole announced they had captured the first clear images of gravitational waves that were generated a trillionth of a trillionth of a trillionth of a second after the Big Bang.
Simply put, astronomers have previously been able to "look back in time" by looking as far outward into space as possible. Here's what that means. Light waves travel at 186,000 miles per second. When you trace a light beam back to its original light source--a star, for example--you are seeing its emitting source as it looked when it sent the light beams forth, all those miles and years ago. Using telescopes at the South Pole, astronomers have looked to the edge of the universe and have been able to see back to the very first light beams generated by the Big Bang. These photons that are hitting the telescopes were generated about 380,000 years after the Big Bang. That's pretty exciting in itself.
But the big news is that scientists have now been able to see the effects of gravitational waves upon the earliest light beams--from before light beams even existed. Looking to the farthest edge of space and examining what is called the "cosmic microwave background," a kind of background noise left over from the Big Bang, astronomers have seen the impressions of polarized wave forms impressing themselves upon the newly born light rays, wave forms which must have preceded visible light and originated, not 380,000 years ago, but 10 to the minus 35 seconds, also known as a trillionth of a trillionth of a trillionth of a second. Not only have they seen the visual patterns of these polarized pressures exerting themselves upon the very first light rays, they have been able to measure their size and their energy, as well as the size of the space that surrounded them. Here's the image:
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Gravitational waves from inflation generate a faint but distinctive twisting pattern in the polarization of the cosmic microwave background, known as a "curl" or B-mode pattern. For the density fluctuations that generate most of the polarization of the CMB, this part of the primordial pattern is exactly zero. Shown here is the actual B-mode pattern observed with the BICEP2 telescope, which is consistent with the pattern predicted for primordial gravitational waves. The line segments show the polarization strength and orientation at different spots on the sky. The red and blue shading shows the degree of clockwise and anti-clockwise twisting of this B-mode pattern. CREDIT: BICEP2 Collaboration
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The quantum-sized gravitational waves are the physical proof linking quantum mechanics with the very large scale space dealt with in Einstein's general relativity. These two scales have been mathematically difficult to write into a single, unified theory. This newest finding of quantum-sized gravitational waves proves the universe of the very small and the very large comes from the same actual space and time and both contain the same basic forces, therefore the very small and very large must be fully compatible and able to be expressed in a single, unified theory.
This news is currently awaiting verification by another source. If proved true, this is the discovery of a lifetime, one that mathematicians and physicists have been seeking since Einstein. Cosmologists admit their confusion in the face of this news. The Standard Model needs amending to accommodate new findings concerning the universe. Primarily, it is time to figure out how gravitational waves could have propagated outward from the Big Bang--what propelled them in the first place? What exactly is it that "Banged"? And how does gravity turn from a repulsive outward force to an attractive force?
The Simple Explanation of Gravitational Waves:
Please have a second look at the Simple Explanation's unified cosmological theory. I am happy to report to you that my theory continues to hold up as all of this new data comes in. The news is not upsetting this applecart the way it is upsetting mainstream cosmologists. Yes, I realize the Simple Explanation vocabulary doesn't sound particularly scientific, but if you can get beyond the language to the mechanism, you will see that this physics works. From the Simple Explanation book:
"Particles rush into our universe from the zero point field at the center, exploding outward, filling our universe from the middle. The outer fractal membrane presses inward to contain the energy exploding outward. Matter flows outward from the middle, repulsed by the energy streaming into the universe from the center, and coherence presses inward from the outer universal boundary."
This chalk drawing represents the way that an inwardly imploding force (like gravity) becomes an outward exploding force (like the Big Bang), and vice versa. Imagine that the outside skin of the figure above not only presses inward on the blue interior, but it attracts others toward itself, as it would if it were a graviton particle. Add a toroidal circulatory flow, as represented by the white arrows, flowing upward from the equator and over the lip into the funnel of the singularity. Can you imagine these forces in motion? Now get this, all of the force associated with the outside skin of the torus is concentrated down from the area of the exterior of the figure to a singularity at the tip of the inward funnel. If you are able to visualize this along with me, you will understand the extreme pressure of that type of concentration.
In the Simple Explanation's model, the pressures exerted at the middle take a little hyperspatial twist there at the middle and explode outward into the interior of the torus. Here is the source of the Bang, as all that pressure pushes into our space-time continuum.
The Simple Explanation cosmology proposes that this primordial toroidal twist arising out of the singularity is the source of the Big Bang. This toroidal pattern has imprinted itself throughout our universe. It's my expectation that the theory of everything will be found to involve toroidal forces affecting all known relationships, from ordinary matter and energetic exchanges, to dark matter and dark energy.
