“Quintessence” –‘Theory About a Great Unknown of the Universe’

ESO Observatories

 

One of the great known unknowns of the universe is the nature of dark energy, a force field making the universe expand faster. Current theories range from end-of-the universe scenarios to dark energy as the manifestation of advanced alien life. “The discovery of dark energy has greatly changed how we think about the laws of nature,” said Edward Witten, creator of string theory and one of the world’s leading theoretical physicist at the Institute for Advanced Study who has been compared to Newton and Einstein.

In May, The Galaxy reported on mind-boggling conjectures made by astrophysicists who have found that for the last 7 billion years or so something is pushing the galaxies, adding energy to them. We are taking a look at them again today as one of our weekend features.  That something they are calling “dark energy,” a force that is real, but so far eludes detection.

One of the most speculative ideas for the mechanism of an accelerating cosmic expansion is called “quintessence”, a relative of the Higgs field that permeates the cosmos.

Cosmologists are now exploring the possibility that the vast majority of the energy in the universe is in the form of a hitherto undiscovered substance called “quintessence” that it causes the expansion of the universe to speed up. Most forms of energy, such as matter or radiation, cause the expansion to slow down due to the attractive force of gravity. For quintessence, however, the gravitational force is repulsive, and this causes the expansion of the universe to accelerate.

Dark Matter –“Is Disappearing Since the Big Bang”

In cosmology, reports Physics World, quintessence is a real form of energy distinct from any normal matter or radiation, or even “dark matter”. Its bulk properties – energy density, pressure and so forth – lead to novel behavior and unusual astrophysical phenomena. So far its existence has only been inferred indirectly from a range of observations, but a number of current and planned experiments will make direct searches for this elusive form of energy.

A new, controversial theory suggests that this dark energy might be getting stronger and denser, leading to a future in which atoms are torn asunder and time ends. “Long, long ago, when the universe was only about 100,000 years old — a buzzing, expanding mass of particles and radiation — a strange new energy field switched on,” writes Dennis Overbye for New York Times Science. “That energy suffused space with a kind of cosmic antigravity, delivering a not-so-gentle boost to the expansion of the universe.”

Dark Matter –“Emerged From an Eon Before the Big Bang”

Then, after another 100,000 years or so, the new field simply switched off, leaving no trace other than a speeded-up universe says a team of astronomers from Johns Hopkins University led by Adam Riess, a Bloomberg Distinguished Professor and Nobel laureate who is an expert in the Hubble constant. In a bold and speculative leap into the past, the team has posited the existence of this field to explain a baffling astronomical puzzle: the universe seems to be expanding faster than it should be.

The Chameleon –“Dark Energy is Hiding from Us”

“A growing mystery about the universe, known as the ‘Hubble Tension,’ is that it appears to be expanding much faster now than predicted even with our latest understanding of its initial conditions and contents,” says Riess. Their research is the first to provide a possible explanation—that the early universe received an infusion of dark energy soon after the Big Bang giving it a boost—which better matches all observations. This theory shows how this ‘tension’ may actually be revealing a new feature of the universe. It also makes predictions which can be tested so that more measurements should tell us if it is correct.”

Secret of Dark Matter –“Enormous Beacon and Planet-Sized Particles” 

The paper explains that if the new exotic matter takes the form of a cosmological constant (like that required to explain the accelerated cosmic expansion in the universe today), agreement can be achieved between Cosmic Microwave Background (CMB) measurements and theoretical expectations in the standard model using supernovae. In fact, the data seem to fit together slightly better with the early dark energy theory. As the paper shows, more precise measurements of the CMB in the future should further test the newly proposed scenario.

The Symmetron Field

The early dark energy resembles that seen in the universe today, although with a density nearly 10 billion times as large. It also resembles the dark energy in the very earliest universe that has been postulated to set the expansion in motion. Combined, these observations suggest that the universe may undergo episodic periods where dark energy becomes important, and if so, the dark energy in the current universe may be just be the latest incarnation.

Incredibly Weird Dark Energy –“Its Source Unknown, Location Unknown, Physics Unknown”

Scientists also predict it could be a symmetron field that pervades space much like the Higgs Field, or a theory that suggests both dark matter and dark energy can be unified into a fluid which possesses a type of ‘negative gravity’, repelling all other material around them, or our hands-down favorite is both dark matter and dark energy can be unified into a fluid which possesses a type of ‘negative gravity’, repelling all other material around them,” says Jamie Farnes from the Oxford University e-Research Center. “The outcome seems rather beautiful: dark energy and dark matter can be unified into a single substance, with both effects being simply explainable as positive mass matter surfing on a sea of negative masses.”

Dark-Matter Life

Perhaps some clever advanced life five billion years ago figured out how to activate the symmetron field, speculates Columbia University’s Caleb Scharf. “it’s a thought-provoking idea, and it echoes some of the thinking of cosmologist Freeman Dyson’s famous 1979 paper “Time Without End,” where he looked at life’s ability in the far, far future to act on an astrophysical scale in an open universe that need not evolve into a state of permanent quiescence. Where life and communication can continue for ever.

Once we start proposing that life could be part of the solution to cosmic mysteries, Scharf concludes, “there’s no end to the fun possibilities. Although dark-matter life is a pretty exotic idea, it’s still conceivable that we might recognize what it is, even capturing it in our labs one day (or being captured by it). We can take a tumble down a different rabbit hole by considering that we don’t recognize advanced life because it forms an integral and unsuspicious part of what we’ve considered to be the natural world.”

Scharf points out that Arthur C. Clarke suggested that any sufficiently advanced technology is going to be indistinguishable from magic. “If you dropped in on a bunch of Paleolithic farmers with your iPhone and a pair of sneakers,” Scharf says, “you’d undoubtedly seem pretty magical. But the contrast is only middling: The farmers would still recognize you as basically like them, and before long they’d be taking selfies. But what if life has moved so far on that it doesn’t just appear magical, but appears like physics?”

If the universe harbors other life, and if some of that life has evolved beyond our own waypoints of complexity an technology, Scharf proposes that we should be considering some very extreme positions.

The Daily Galaxy via Physics World, Johns Hopkins University, New York Times, WBUR and Nautil.us

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