Welcome to the biggest mystery in physics: one of the great known unknowns of the universe is the nature of dark energy, an antigravitaional force field making the universe expand faster. Current theories range from end-of-the universe scenarios to dark energy as the manifestation of advanced intelligent life. It is the proverbial elephant in the “cosmic” room.“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 physicists at the Institute for Advanced Study in Princeton, N.J. who has been compared to Newton and Einstein. It could turn out that dark energy is some as-yet-undiscovered “fifth force,” or the result of not understanding gravity, adds Witten.
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.
Strange New Energy Field Switches On
“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.”
Switched Off –Leaving a Speeded-Up Universe
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 “Hubble Tension” Enigma
“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.”
The research 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.
Early Universe Dark Energy 10-Billion Times the Present
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 the latest incarnation.
The Symmetron Field–A Fifth Force
Scientists also predict it could be a symmetron field –a fifth force–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, says Jamie Farnes with the Oxford University e-Research Center.
“The outcome seems rather beautiful,” says Farnes, “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.”
“Quintessence”–A Field Activated by Alien Intelligence?
One idea for the mechanism of an accelerating cosmic expansion is a real form of energy, a gravitational force that is repulsive –a mysterious substance called quintessence–a relative of the Higgs field that permeates the cosmos. A
Perhaps some clever life 5 billion years ago figured out how to activate that field, speculates Columbia University astrophysicist Caleb Scharf in “Is Physical Law an Alien Intelligence”. How? “Beats me,” he says, “but 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 the acceleration of the expansion of the universe may be a temporary phenomenon. Dyson looked at intelligent 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 forever.
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.”
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