Astronomers have found evidence of a giant void that could be the largest known structure in the universe. The “supervoid” solves a controversial cosmic puzzle: it explains the origin of a large and anomalously cold region of the sky. However, future observations are needed to confirm the discovery and determine whether the void is unique.
The so-called cold spot can be seen in maps of the Cosmic Microwave Background (CMB), which is the radiation left over from the birth of the universe. It was first discovered by NASA’s Wilkinson Microwave Anisotropy Probe (WMAP) in 2004 and confirmed by ESA’s Planck Satellite. For more than a decade, astronomers have failed to explain its existence. But there has been no shortage of suggestions, with unproven and controversial theories being put forward including imprints of parallel universes, called the multiverse theory, and exotic physics in the early universe.
Now an international team of astronomers led by Istvan Szapudi of the Institute for Astronomy at The University of Hawaii at Manoa have found evidence for one of the theories: a supervoid, in which the density of galaxies is much lower than usual in the known universe.
Last week, BICEP2 scientists — who in March announced evidence of cosmic inflation, a potentially Nobel-worthy find — threw handfuls of dust on the grave of their own results. The official paper [pdf], just published on the BICEP website, tells the story of how they mistook cosmic dust for “primordial gravitational waves,” and why everybody needs to calm down and stop trying to bury inflation, too.
Just 10-35 seconds after the Big Bang, cosmologists (or at least most of them) believe the universe expanded in hyperdrive — faster than it ever has since and faster than it ever will again. This ballooning, called inflation, smoothed everything out. It turned the cosmos into the roughly homogenous place we see today, and perhaps created other universes that add up to the sci-fi-sounding “multiverse.”
But it’s difficult to find direct evidence that inflation actually happened (after all, it was a long time ago). That’s where B-modes, which the BICEP2 team saw, come in.
The claim made headlines worldwide, hailing one of the biggest scientific discoveries in decades. After 35 years of research, astronomers said in March, they had found evidence that the universe underwent a brief but ultra-fast expansion when it was roughly a trillionth of a trillionth of a trillionth of a second old. The research team could see a Nobel Prize looming in the distance. So they popped bottles of bubbly in celebration and shared their excitement with the world.
But results confirmed today indicate that the fizz has long gone out of those findings. A second team of astronomers, which includes the initial BICEP2 team itself, used the European Space Agency’s Planck satellite to show that the twisting patterns did not come from the cosmic microwave background at all. They’re nothing but swirling patterns of dust.
“Interdisciplinary” is a huge buzzword in academia right now. But for science, it has a long history of success. Some of the best science happens when researchers cross-pollinate, applying knowledge from other fields to inform their research.
One of the best such examples in physics was the concept of a Higgs field, which led to the 2013 Nobel Prize in physics. Few people outside the physics community know that the insight to the behavior of the proposed Higgs particle actually came from solid state physics, a branch of study that looks at the processes that take place inside condensed matter such as a superconductor.
Now cosmologists are trying to borrow some ideas of their own. The new discovery of gravitational waves — the biggest news in cosmology this century — focuses fresh attention on a field in which recent progress has otherwise been slow. Cosmologists are now attempting to explore novel ways of trying to understand what happened in the Big Bang, and what, if anything, caused the gargantuan explosion believed to have launched our universe on its way. To do so they’ve turned their attention to areas of physics far removed from outer space: hydrology and turbulence. The idea is pretty clever: to view the universe as an ocean.
In 1917, a year after Albert Einstein’s general theory of relativity was published—but still two years before he would become the international celebrity we know—Einstein chose to tackle the entire universe. For anyone else, this might seem an exceedingly ambitious task—but this was Einstein.
Einstein began by applying his field equations of gravitation to what he considered to be the entire universe. The field equations were the mathematical essence of his general theory of relativity, which extended Newton’s theory of gravity to realms where speeds approach that of light and masses are very large. But his math was better than he wanted to believe—his equations told him that the universe could not stay static: it had to either expand or contract. Einstein chose to ignore what his mathematics was telling him.
The story of Einstein’s solution to this problem—the maligned “cosmological constant” (also called lambda)—is well known in the history of science. But this story, it turns out, has a different ending than everyone thought: Einstein late in life returned to considering his disgraced lambda. And his conversion foretold lambda’s use in an unexpected new setting, with immense relevance to a key conundrum in modern physics and cosmology: dark energy.
By Govert Schilling
Just over a week ago, at three miles above sea level in the Chilean Atacama desert, Atacameño indians offered gifts to Mother Earth in a traditional ceremony to bless a decidedly modern object: the Atacama Large Millimeter/submillimeter Array (ALMA). Four days later, on March 13, the largest-ever ground-based astronomical observatory was officially inaugurated. “ALMA is now a reality, and not a fairy tale anymore,” said Dutch astronomer Thijs de Graauw, the project’s director.
ALMA (Spanish for “soul”) consists of 66 antennas, most of them 40 feet across. They are equipped with sensitive receivers to detect millimeter and submillimeter waves from space – radiation in between radio waves and infrared light. This relatively long-wavelength radiation is emitted by the coolest objects in the Universe, such as the dark molecular clouds that spawn new stars and planets. What’s more, interstellar molecules, including complex hydrocarbons and other molecules necessary for life, can only be identified using this type of radiation. Cosmic millimeter and submillimeter radiation has never been observed in much detail before, so astronomers all over the world have eagerly anticipated the ALMA inauguration.
Amir D. Aczel writes often about physics and cosmology. His book about the discovery of the Higgs boson, Present at the Creation: Discovering the Higgs Boson, is published in paperback by Broadway Books in November 2012.
If somebody told you that there are angels floating in space, observing our world and forming their impressions of our everyday reality, you would think that this person is nuts—a religious fanatic with an active imagination, and certainly not a scientist. Scientists, as we all know, are rational beings who believe only in what nature reveals to us through experimentation and observation, coupled with theory that is never divorced from the physical measurements they make. The link between the two remains tightly regulated through the strict rules of the scientific method.
So how do you explain the bizarre fact that, for about five years now, some of the world’s most prominent physicists have been describing a scenario—which they seem to truly believe may be real—in which, instead of the Biblical angels, space is permeated by disembodied brains?
These compact, conscious observers, called “Boltzmann brains,” cruise the vastness of intergalactic space, and beyond it, to the infinite “multiverse” that some scientists believe exists outside the reaches of the universe we observe through our telescopes and satellites. Their consciousness makes the Boltzmann brains recreate our reality. They imagine life such as the one you and I believe we are experiencing here on Earth, to the point that these brains in space may think that they are living on a planet like ours, that they may even be us. Some recent physics papers and commentaries have even explored the possible limits on the number of Boltzmann brains in the universe as compared with “real” brains, in an effort to estimate the probability that we are real rather than Boltzmann entities.