If life is widespread in our universe, and we have every reason to believe it, why aren’t we seeing evidence of it everywhere?
This is the essence of the Fermi Paradox, a question that has plagued astronomers and cosmologists almost since the birth of modern astronomy.
It’s also the reason for the Hart-Tipler conjecture, one of the many (many!) proposed resolutions, which states that if advanced life had arisen in our galaxy at some point in the past, we would see signs of its activity everywhere. Potential indications include self-replicating probes, megastructures, and other type III-like activities.
On the other hand, several proposed resolutions challenge the notion that advanced life would function on such massive scales. Others suggest that advanced extraterrestrial civilizations would be involved in activities and locations that would make them less conspicuous. In a recent study, a German-Georgian team of researchers suggested that advanced extraterrestrial civilizations could use black holes as quantum computers. This makes sense from a computational point of view and provides an explanation for the apparent lack of activity we see when looking at the cosmos.
The research was led by Gia Dvali, a theoretical physicist at the Max Planck Institute for Physics and the Physics Chair at the Ludwig Maximilian University in Munich, and Zaza Osmanov, a professor of physics at the Free University of Tbilisi and a researcher conducted by the Kharadze Georgian National Astrophysical Observatory. The paper describing their findings has recently appeared online and is being reviewed for publication in the International Journal of Astrobiology.
The first SETI survey (Project Ozma) was conducted in 1960 and led by the famous astrophysicist Frank Drake (who proposed the Drake equation). This survey relied on the Green Bank Observatory’s 26-meter radio telescope to listen for radio transmissions from the nearby Tau Ceti and Epsilon Eridani star systems. Since then, the vast majority of SETI projects have focused on the search for radio technosignatures, attributed to the ability of radio waves to propagate through interstellar space. As explained by Dvali and Osmanov universe today by email:
“Currently, we’re mostly looking for radio messages, and there have been several attempts to probe the sky to find the so-called Dyson Sphere candidates – megastructures built around stars. On the other hand, SETI’s problem is so complex that one should test all possible channels.
“A whole ‘spectrum’ of technosignatures could be much broader: for example, infrared or optical emission from megastructures that have also been built around pulsars, white dwarfs and black holes. A whole new “direction” must be the search for an anomalous spectral variability of these technosignatures that could distinguish them from normal astrophysical objects.”
Limitations of SETI
For many researchers, this limited focus is one of the main reasons SETI failed to find evidence of technosignatures. In recent years, astronomers and astrophysicists have recommended expanding the search to include searches for other technosignatures and methods – such as Messaging Extraterrestrial Intelligence (METI). These include directed energy (lasers), neutrino emissions, quantum communications, and gravitational waves, many of which are detailed in the NASA Technosignature Report (released in 2018) and the TechnoClimes 2020 workshop.
For their study, Dvali and Osmanov suggest looking for something completely different: evidence of large-scale quantum computing. The benefits of quantum computing are well documented, including the ability to process information exponentially faster than digital computing and to be immune to decryption. Given the speed at which quantum computing is advancing today, it is entirely logical to assume that an advanced civilization could adapt this technology on a much larger scale. Said Dvali and Osmanov:
“No matter how advanced a civilization is, or how different its particle composition and chemistry is from ours, we are united by the laws of quantum physics and gravity. These laws tell us that the most efficient stores of quantum information are black holes.
“Although our recent studies show that there could theoretically be devices created by non-gravitational interactions that also saturate information storage capacity (the so-called ‘saturation’), black holes are the clear champions. Accordingly, any sufficiently advanced ETI will be expected to use it for information storage and processing.”
This idea builds on the work of Nobel laureate Roger Penrose, who famously suggested that limitless energy could be extracted from a black hole by tapping into the ergosphere. This space lies just outside the event horizon, where infalling matter forms a disk that accelerates to near the speed of light and emits enormous amounts of radiation. Several researchers have suggested that this could be the ultimate power source for advanced ETIs, either by injecting matter into an SMBH (and harnessing the resulting radiation) or simply harnessing the energy already emitted.
Two options for this latter scenario are to harness the angular momentum of their accretion disks (the “Penrose process”) or capture the heat and energy generated by their hypervelocity jets (perhaps in the form of a Dyson Sphere). In their later work, Dvali and Osmanov propose that black holes may be the ultimate source of computation. This is based on the notions that: a) a civilization’s progress is directly correlated to its level of computing power, and b) that there are certain universal markers of computing progress that can be used as potential technosignatures for SETI.
Black holes for quantum computing
Using the principles of quantum mechanics, Dvali and Osmanov explained that black holes are the most efficient capacitors for quantum information. These black holes would likely be artificial and micro-sized rather than large and naturally occurring (for computational efficiency reasons). As a result, they argue, these black holes would be more energetic than naturally occurring ones:
“By analyzing the simple scaling properties of information retrieval time, we showed that optimizing information volume and processing time suggests that investing energy in creating many microscopic black holes, as opposed to a few large ones, is maximally beneficial for ETI.
“First, the micro black holes emit at much higher intensity and in the higher energy spectrum of Hawking radiation. Second, such black holes must be created by high-energy particle collisions in accelerators. This fabrication necessarily provides an accompanying high-energy radiation signature.”
Hawking radiation, named in honor of the late and great Stephen Hawking, is theoretically released just outside a black hole’s event horizon due to relativistic quantum effects. The emission of this radiation reduces the mass and rotational energy of black holes, theoretically leading to their eventual vaporization. The resulting Hawking radiation, Dvali and Osomanov said, would be “democratic” in nature, meaning it would produce many different types of subatomic particles detectable by modern instruments:
“The great thing about Hawking radiation is that it is universal in all types of particles that exist. In doing so, ETI quantum computers have to emit “ordinary” particles such as neutrinos and photons. Neutrinos in particular are excellent messengers due to their extraordinary ability to penetrate, which avoids the possibility of x-rays.
“In particular, this offers novel fingerprints of ETI in the form of a flux of very high-energy neutrinos, originating both from the Hawking radiation from information micro-black holes store and from the collision ‘factories’ that produce them. The Hawking component of the radiation is expected to be a superposition of very high energy blackbody spectra. In the work, we showed that the IceCube observatory may be able to observe such technosignatures. However, this is just one possible example of a very exciting new direction for SETI.”
In many ways, this theory mirrors the logic of the Barrow scale proposed by astrophysicist and mathematician John D. Barrow in 1998. A revision of the Kardashev scale, the Barrow scale, suggests that civilizations should not be characterized by their physical mastery of outer space (i.e. planet, solar system, galaxy, etc.) but of inner space – i.e. the molecular, atomic and quantum realms. This scale is central to the Transcension Hypothesis, a proposed resolution of the Fermi paradox that suggests ETIs would have gone beyond anything we would recognize.
A resolution to Fermi?
Herein lies another exciting aspect of this theory, which offers another possible solution to the Fermi paradox. As they explained:
“Until now, we have completely missed a natural direction for SETI in the form of high-energy neutrinos and other particles produced by Hawking radiation from artificial black holes. Therefore, various experimental searches for such high-energy particles can potentially shed extremely important light on the presence of advanced ETI in the observable part of the Universe.”
In short, we might see a “great silence” when we look out into the cosmos because we’ve been looking for the wrong techno signatures. If extraterrestrial life has made a leap onto humanity (which seems reasonable given the age of the universe), it stands to reason that it long ago outgrew radio communications and digital computing. Another benefit of this theory is that it doesn’t have to apply to all ETIs to explain why we haven’t heard from any civilization yet.
Given the exponential rate at which computing advances (using humanity as a template), advanced civilizations may have a brief window in which to broadcast in radio wavelengths. This is an important part of the Drake equation: the L Parameter related to the amount of time civilizations have to send detectable signals into space. In the meantime, this study offers another potential SETI poll technosignature to look for in the years to come. The paradox persists, but we need only find a hint of advanced life to solve it.
This article was originally published on universe today by Matt Williams. Read the original article here.