DESI will map millions of galaxies and measure how fast they’re moving. This dataset can tell astronomers how much dark energy exists and how that’s changed.
There are a lot of unsolved mysteries in the Universe, but dark energy is the most confusing. Here’s why.
A trio of researchers with the University of Manchester, Università di Roma ‘La Sapienza’ and Sorbonne Universities has sparked a major debate among cosmologists by claiming that data from the Planck space observatory suggests the universe is a sphere—not flat, as current conventional theory suggests. In their paper published in the journal Nature Astronomy, Eleonora Di Valentino, Alessandro Melchiorri and Joseph Silk outline their arguments and suggest their findings indicate that there exists a cosmological crisis that must be addressed.
Conventional theory, which backs inflation theory, suggests that after the Big Bang, the universe expanded in a way that was flat—two lights shone in parallel would travel forever in parallel. But now, after studying data sent back to Earth from the Planck space observatory (which mapped cosmic microwave background radiation over the years 2009 to 2013) Di Valentino, Melchiorri and Silk have come to disagree with conventional thinking. They claim that there is evidence that the universe is closed—that it is shaped like a sphere. If you shine two lights into the dark of space, they suggest, at some point, the light would come back around to you from behind.
The researchers came to this conclusion after looking at data from the Planck space observatory that showed a discrepancy between the concentration of dark matter and dark energy and outward expansion; there was more gravitational lensing than theory has predicted. Such an imbalance, they claim, would have the universe collapsing in on itself, resulting in a sphere shape. Others who have looked at the same data prior to this new effort have called the data from the observatory a statistical fluke. The research trio note that there are other problems with the flat theory as well, such as scientists’ inability to accurately measure the Hubble constant; each team that tries finds a different answer. There have also been problems with reconciling surveys of dark energy with a flat model.
According to the theory of General Relativity, mass curves spacetime. As a result, the overall mass of the universe determines its shape. Indeed, scientists have been known to calculate the “critical density” of the universe, which is proportional to the square of the Hubble constant, a variable used in estimating the size, age and expansion rate of the universe. If the actual density of the universe is less than the critical density, it is predicted that the universe will forever expand, as there isn’t enough matter to stop it. This creates a flat, and open, universe.
Yet if the density of the universe is more than the critical density, then that means it has enough mass to stop expanding, which is what the latest study using Planck data is suggesting.
A closed universe could end consequentially with a scenario known as the “Big Crunch” — the opposite of a Big Bang, in a sense, and a state in which the universe contracts until it is compressed again to a single energetic point.
For years scientists have believed our universe was as flat as a piece of paper, but new evidence has suggested it is curved like a giant inflated balloon.
A recent study analyzed data from the cosmic microwave background, the faint echo of the Big Bang, and discovered gravity seems to bend the microwaves.
The origin of the universe started with the Big Bang, but how the supernova explosion ignited has long been a mystery – until now. In a new paper appearing today in Science Magazine, researchers detailed the mechanisms that could cause the explosion, which is key for the models that scientists use to understand the origin of the universe.
Two and a half months since Erik Verlinde submitted his entropic gravity paper, and all of physics and cosmology has turned into entropy. Well, I am exaggerating a bit, and perhaps more than just a bit. Yet, fact is that within two weeks of Erik’s publication a steady stream of ‘entropic everything’ papers has developed at a rate of close to one paper per day. Gravity, Einstein’s equations, cosmic expansion, dark energy, primordial inflation, dark mass: it’s all entropic. Chaos rules. Entropy is king!
Or is it?
Could it be that an ‘entropic bandwagon’ has started rolling? Is this all not just a fad appealing to scientist tired of string theory? What is this elusive entropic force anyway? Do these folks really believe bits of information attract each other?
Scientists at The Australian National University (ANU) have found a way to better detect all collisions of stellar-mass black holes in the universe.
Stellar-mass black holes are formed by the gravitational collapse of a star. Their collisions are some of the most violent events in the universe, creating gravitational waves or ripples in space-time.
These ripples are miniscule and detected using laser interferometers. Until now, many signals have been drowned out by so-called quantum noise on the laser light pushing the mirrors of the laser interferometer around—making the measurements fuzzy or imprecise.
The hunt for dark energy has gained a new weapon, with the first test of the Dark Energy Spectroscopic Instrument (DESI) being completed recently. DESI is installed atop the Nicholas U. Mayall Telescope at Kitt Peak National Observatory outside Tucson, Arizona and will search for evidence of the mysterious energy which makes up 68% of the universe and speeds up its expansion.
“After a decade in planning and R&D, installation and assembly, we are delighted that DESI can soon begin its quest to unravel the mystery of dark energy,” DESI Director Michael Levi of the Department of Energy’s Lawrence Berkeley National Laboratory said in a statement. “Most of the universe’s matter and energy are dark and unknown, and next-generation experiments like DESI are our best bet for unraveling these mysteries. I am thrilled to see this new experiment come to life.”
To compile the first image shown above, DESI used its 5,000 spectroscopic “eyes” which peer out into the night sky. Each eye can focus on a single object to take in the light it produces. In this case, the instrument collected data from a small region in the Triangulum galaxy.
THE Big Bang theory has long been accepted as scientific fact as an explanation of the universe came into being – but it has always begged the question ‘what happened before the big bang?’
