New research project proposals to test all the ways there could be intelligence in a semi-detached binary are most welcome.
You can vote to prioritize existing projects and suggest your own ideas. The stellivore hypothesis is summarized here, and some research proposals are described below and in more details in Chapter 9 of (Vidal 2014):
- Gamma-ray bursts and binaries
- Kleiber’s law in binaries
- Scale relativity and binaries
- Assessing or decoding the informational complexity of pulsars’ pulses
Gamma-ray bursts and binaries
What do we expect? A study of the resiliency of binary systems to gamma-ray bursts.
What result is entitling to the prize? Either showing that binaries get strongly disturbed, dislocated or destroyed by gamma ray bursts (which would tend to falsify the stellivore hypothesis), or that they are very robust to such disturbances (which would tend to corroborate the stellivore hypothesis).
Are stellivores protected from gamma-ray bursts? Such events are of a rare violence and a galactic gamma-ray burst could wipe out eukaryotes in a range of 14 kpc from the explosion (see Scalo and Wheeler 2002; and also Ćirković, Vukotić, and Dragićević 2009). Long-lived civilizations would certainly anticipate such rare but probable catastrophes.
Kleiber’s laws and semi-detached binaries
What robust biological laws could be applied to binaries? Kleiber’s law (Kleiber 1932) is the observation that in living organisms the metabolic rate scales to the ¾ power of its mass. It is a remarkable law, because it holds over 16 orders of magnitude –although the scaling exponent changes slightly (see DeLong et al. 2010 for a recent review). This validity across so many scales suggests that it could hold even for macroscopic living systems, such as putative stellivores. The figure below illustrates this law.
“Relationship between whole organism metabolic rate and body mass for heterotrophic prokaryotes, protists, and metazoans plotted on logarithmic axes.” (DeLong et al. 2010, 12942)
Now, does this law apply to transient accreting binaries? The hypothesis is that, if binaries are stellivores, they should fit with this law. If not, it is less likely. How can we test this? It is easy. We need to gather the relevant data for binaries. We can simply interpret the accretion rate as a metabolic rate (both are energy flow metrics); and keep on the x-axis the mass of the primary.
What do we expect? Ideally, a comprehensive data gathering about accretion rates in binaries, and the mass of the primary body.
What result is entitling to the prize? Either showing that binaries follow Kleiber’s law, which is valid in biology (in this case, showing that accretion rate would scale to ~3/4 power of the primary’s mass); showing that binaries do not follow at all such a biological law is also entitling to the prize.
Kepler’s law famously applies to planets, but does Kleiber’s law apply to binaries?
Note that this research program could also be coupled with a systematic calculation of the free energy rate density complexity metric proposed by Chaisson.
Scale Relativity and Binaries
Scale relativity (see e.g. L. Nottale 2011) generates probability distributions for the formation of gravitational structures. It gives probabilities to have single, double, triple or n-body systems. Preliminary results explain why pairs of galaxies are so common (L. Nottale 2011, 654–658).
This project consists in applying scale relativity to the formation of binary systems. If binaries are stellivores, the prediction of scale relativity should fail. Indeed, we should find more binary systems than what would be formed by natural gravitational formation. Or there should be proportionally less pairs of galaxies than binary systems. Note that the picture could be more complicated if putative stellivores migrate and leave single depleted stars.
Furthermore, applying the inverse distance-development principle, further and further away galaxies should fit more and more the predictions of scale relativity. Of course, this project represents a lot of work, but it is a global approach which, even if it ends up dismissing the stellivore hypothesis, would teach us a lot about star formation.
What do we expect? A study of the distribution of binary systems in our galaxy and possibly in others.
If it succeeds, we would have an estimate of the number of intelligent civilizations in the galaxy, simply by subtracting the observed number of binaries with the predicted number.
Pulsars decoding
Finally and most importantly, a convincing proof of ETI should include information processing. This is why I insisted that the assessment of whether there are messages in pulsars should be a priority (see section 9.4.6 Are Pulsars Artificial Output Transducers?).
There is a lot of new research in pulsars, and the pulses display an impressive array of behavior, not obvious to explain with “natural explanations”. Decoding an extraterrestrial message is probably an amazingly difficult task. But a first easier step is to assess if pulses display informational complexity (e.g. according to Kolmogorov complexity or Bennett’s logical depth). Pulsars signals could be benchmarked against “natural” signals (e.g. sea waves) and “artificial” signals (e.g. wifi). If they score like sea waves, they are more likely natural; if they score like wifi signal, they are more likely artificial. Again, corroboration or refutation are entitling to the prize.
Pulsars might also constitute an artificial galactic navigation system. Emadzadeh and Speyer (2011) summarize research about absolute and relative navigation with X-ray pulsars. Finding typical features of an artificial navigation system is entitling to the prize.
Bibliography
Ćirković, Milan M., Branislav Vukotić, and Ivana Dragićević. 2009. “Galactic Punctuated Equilibrium: How to Undermine Carter’s Anthropic Argument in Astrobiology.” Astrobiology 9 (5) (June): 491–501. doi:10.1089/ast.2007.0200. http://online.liebertpub.com/doi/abs/10.1089/ast.2007.0200.
DeLong, John P., Jordan G. Okie, Melanie E. Moses, Richard M. Sibly, and James H. Brown. 2010. “Shifts in Metabolic Scaling, Production, and Efficiency Across Major Evolutionary Transitions of Life.” Proceedings of the National Academy of Sciences 107 (29) (July 20): 12941 –12945. doi:10.1073/pnas.1007783107.
Dick, Steven J. 1996. The Biological Universe: The Twentieth Century Extraterrestrial Life Debate and the Limits of Science. Cambridge University Press.
Isalgue, Antonio, Helena Coch, and Rafael Serra. 2007. “Scaling Laws and the Modern City.” Physica A: Statistical Mechanics and Its Applications 382 (2) (August 15): 643–649. doi:10.1016/j.physa.2007.04.019.
Kleiber, M. 1932. “Body Size and Metabolism.” Hilgardia 6: 315–351. http://biology.unm.edu/jHBrown/Miami/Kleiber1932.pdf.
Nottale, L. 2011. Scale Relativity And Fractal Space-Time: A New Approach to Unifying Relativity and Quantum Mechanics. World Scientific Publishing Company.
Scalo, John, and J. Craig Wheeler. 2002. “Astrophysical and Astrobiological Implications of Gamma‐Ray Burst Properties.” The Astrophysical Journal 566 (2) (February 20): 723–737. doi:10.1086/338329. http://arxiv.org/abs/astro-ph/9912564.
Vidal, C. 2014 The Beginning and the End: The Meaning of Life in a Cosmological Perspective. Springer, Frontiers Collection. Preprint at: http://arxiv.org/abs/1301.1648.
Vidal, C. 2016. “Stellivore Extraterrestrials? Binary Stars as Living Systems.” Acta Astronautica 128: 251–56. doi:10.1016/j.actaastro.2016.06.038. https://zenodo.org/record/164853
High Energy Astrobiology 