Several mind-boggling conjectures about the existence of advanced alien civilizations have been made by astrophysicists who have found that for the last 7 billion years or so something is pushing the galaxies, adding energy to them. 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.
“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 in Princeton, N.J. who has been compared to Newton and Einstein.
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.
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.
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.”
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.
“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 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.
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.”
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 and technology, Scharf proposes that we should be considering some very extreme possibilities.
Roger Penrose’s “Crazy” Erebon Field
“According to British physicist, Sir Roger Penrose’s conformal cyclic cosmology, the universe goes through an infinite series of ‘aeons,’ each of which starts with a phase resembling a big bang, then forming galactic structures as usual, then cooling down as stars die. In the end the only thing that’s left are evaporating black holes and thinly dispersed radiation.”
“Of course, the theory is “crazy”, says Penrose, “but I strongly believe (in view of observational facts that seem to be coming to light) that we have to take it seriously.”
Penrose then conjectures a slight change to particle physics that allows him to attach the end of one aeon to the beginning of another, and everything starts anew with the next bang,” writes Sabine Hossenfelder in her Backreaction blog. Hossenfelder is a research fellow at the Frankfurt Institute for Advanced Studies who focuses on physics beyond the standard model.
This match between one aeon’s end and another’s beginning necessitates the introduction of a new field – the “erebon” – that makes up dark matter, and that decays throughout the coming aeon. We previously met the erobons because Penrose argued their decay should create noise in gravitational wave interferometers.
If Penrose’s CCC hypothesis is correct, we should also be able to see some left-over information from the previous aeon in the cosmic microwave background around us. To that end, Penrose has previously looked for low-variance rings in the CMB, that he argued should be caused by collisions between supermassive black holes in the aeon prior to ours. The search for that, however, turned out to be inconclusive. In a recent paper with Daniel An and Krzysztof Meissner he has now suggested to look instead for a different signal.
The new signal that Penrose et al are looking for are points in the CMB at the places where in the previous aeon supermassive black holes evaporated. He and collaborators called these “Hawking Points” in memory of the late Stephen Hawking. The idea is that when you glue together the end of the previous aeon with the beginning of ours, you squeeze together the radiation emitted by those black holes and that makes a blurry point at which the CMB temperature is slightly increased.
Penrose estimates the total number of such Hawking Points which should be in the total cosmic microwave background is about a million. The analysis in the paper, covering about 1/3 of the sky, finds tentative evidence for about 20. What’s with the rest remains somewhat unclear, presumably too weak to be observed.
They look for these features by generating fake “normal” CMBs, following standard procedure, and then trying to find Hawking Points in these simulations. They have now done about 5000 of such simulations, but none of them, they claim, has features similar to the actually observed CMB. This makes their detection highly statistically significant, with a chance of less than 1/5000 that the Hawking Points which they find in the CMB are due to random chance.
“Extraterrestrials No More Speculative than Dark Matter”
Enter Harvard’s Avi Loeb: “I don’t see extraterrestrials as more speculative than dark matter or extra dimensions. I think it’s the other way around.”
When Oumuamua entered our Solar System, Loeb observed in an interview with Endless Thread, “it spun around over a period of eight hours its brightness changed by a factor of 10. And that’s much more than any object born in the solar system, such as asteroids or comets, that change by at most a factor of three or so.
Another weird anomaly, he said, was the mere fact that it was discovered, [which] implies that the population of such objects is much more abundant than we anticipated. Unless of course it’s on a very specialized orbit such that it’s not a member of a population of random objects.
Mirroring Scarf’s argument, Loeb concluded, “the entire discussion about ‘Oumuamua is very similar to an imaginary scene where you see a cave person being shown an iPhone. And this cave person would look at it and think that it might be a rock. And then would show it to other members of his or her tribe and the people there would still say, No, it’s probably a rock and how dare you say something else, how dare you talk about something that is different than a rock because rocks are everything that we are familiar with.
“And so, to me,” Loeb concludes, “not even putting aliens on the table for discussion is a crime! Because if you look at the history of science, you know, Galileo Galilei argued that the Earth moves around the sun and he was put under house arrest for that. Now, this of course didn’t change the facts. It doesn’t matter what is being said on Twitter, what is being said in other social media or among scientists. This thing is what it is, right? And, you know, the Earth still moves around the sun irrespective of what the church said a while ago. And the fact that Galileo suffered for it has no relevance to nature.”
“One can imagine a probe that brought the seeds of life in the form of microbes or instead a 3-D printer that produced these seeds out of the raw materials on Earth based on a prescribed blueprint,” Loeb wrote. “The universal left-handedness (chirality) of all life-forms on Earth without exception can be interpreted as stemming from a single panspermia event, be it natural (through a rock arriving from space) or artificial in origin . Even in this context, our imagination of what aliens might do will improve once we are able to produce synthetic life in the laboratory.”
Image credit: With thanks to Pixabay