The Starivore Hypothesis: Why the Galaxy May be Teeming with (Post)biology

Clément Vidal
Centrum Leo Apostel (CLEA)
Evolution, Complexity and Cognition (ECCO)
Presented in the Embryo Physics Course, March 13, 2013


This talk proposes a new concrete hypothesis to assess the existence of advanced extraterrestrial life. I first point out two methodological fallacies, *naturality-of-the-gaps* and * artificiality-of-the-gaps* and propose a more balanced *astrobiological stance*, which does not prejudices the naturality or artificiality of suspicious phenomena we observe. I point out many limiting and implicit assumptions in SETI, in order to propose a “Zen SETI”, thus opening the search space. In particular, I outline the case for postbiological evolution, or the probable transition of life to another organizational paradigm than biochemistry. I then discuss criteria to distinguish natural from artificial phenomena, starting with global criteria (*strangeness heuristic* and *inverse distance-development principle*); then thermodynamical criteria (*thermodynamic disequilibrium* and *energy flow control*); and finally present living systems criteria (Miller’s nineteen critical functional subsystems). Then I introduce a two-dimensional metric for civilizational development, using the Kardashev scale of energy consumption increase and the Barrow scale of inward manipulation. Taken together, these two civilizational development trends lead to an argument that some existing binary stars may actually be advanced extraterrestrials. Since those putative beings actively feed on stars, I call them *starivores*. I elaborate another independent thermodynamical argument for their existence, with a metabolic interpretation of some binary stars in accretion. I further substantiate the hypothesis with a tentative living systems interpretation. Ten critical living subsystems are suggested to apply to interacting binaries composed of a primary white dwarf, neutron star or black hole. I critically discuss the hypothesis by formulating and replying objections. The question of artificiality remains open, but I propose four concrete research proposals and a prize to further continue and motivate the scientific assessment of this hypothesis.

More Information

The detailed version of the hypothesis is in Chapter 9 of:

Vidal, C. 2013 – *The Beginning and the End: the Meaning of Life in a
Cosmological Perspective*, PhD Thesis, 360 pages,
to be defended at the Free University Brussels (Vrije Universiteit Brussel)

A recent short paper summarizes the core arguments:

Vidal, C. 2013. “Starivore Extraterrestrials? A Metabolic Account of
Interacting Binary Stars”

*Working Paper*.




Clément Vidal is a researcher at the Free University of Brussels (Vrije Universiteit Brussel). He has a background in Philosophy, Mathematical Logic (master’s degrees at the University Paris I Panthéon-Sorbonne, France) and Cognitive Sciences (MSc, EHESS/ENS/Paris 5/Paris 6, France). He has broad interdisciplinary interests in astrobiology, complexity sciences, evolutionary theory, philosophy of science, cognitive sciences and praxeology. He recently finished to write his PhD on the origin of the universe and the far-future of intelligent life. 



5 responses to “The Starivore Hypothesis: Why the Galaxy May be Teeming with (Post)biology”

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  1. Dear Clément,

    I will repeat my question about thermodynamics. First, I do not understand how for example energy flow control follows from the laws of thermodynamics. Second, thermodynamics is developed under the assumption of additivity. That is assumed that for a system consisting from several parts the internal energy and the entropy is a sum over the parts

    U = U1 + U2 + U3 …
    S = S1 + S2 + S3 …

    This is definitely not the case for the Universe, where one cannot neglect gravitation. Hence, it is unclear to me what thermodynamics you apply to the whole Universe.


  2. Clément says:

    Dear Evgenii,

    Your question/critique makes sense, and maybe I haven’t answered you properly during the seminar. Energy flow control does NOT follow from classical thermodynamics. This is a property found in far-for-equilibrium systems, especially living systems. In other words, it is an interesting feature to look at, precisely because the 2nd law of thermodynamics would tend to annihilate such energetic behavior.

    The question of applying thermodynamics to the universe is a tricky one, because, as you notice, we can not neglect gravitation. I shortly articulated the problem in a short paper (Vidal 2012, p312 of the preprint; 30-31 of the postprint):

    “If we draw the spectrum of the observed microwave background radiation (MBR), it turns out to be very close to the Planck spectrum. This Planck spectrum is a typical example of thermal equilibrium, i.e. a state with maximum entropy. However, following the second law of thermodynamics, if entropy can only increase, going back to the initial state of our universe, it should be at a minimum entropy. Hence the paradox, was the initial entropy of the universe maximum or minimum?
    The answer, writes Penrose, is that the MBR is to be interpreted as a thermal equilibrium between radiation and matter. We can also note that the MBR is not primordial from the point of view of the origin of the universe, since the universe is already about 400 000 years old at that time. So, its maximal entropy could be interpreted as a final state. Anyway, since we do not have a theory of quantum gravity, the entropy related to the gravitational field remains an open question”

    I hope this helps.

    Vidal, C. 2012. “Fine-tuning, Quantum Mechanics and Cosmological Artificial Selection.” Foundations of Science 17 (1): 29–38. doi:10.1007/s10699-010-9219-2.

  3. I am not sure, if I understand the origin of your statement

    “precisely because the 2nd law of thermodynamics would tend to annihilate such energetic behavior.”

    Recently I had a discussion with biologists and I copy below my comment.


    A small comment to the statement from the link above.

    “and that the idea of their improving rather than harming organisms is contrary to the Second Law of Thermodynamics, which tells us that matter and energy naturally tend toward greater randomness rather than greater order and complexity.”

    I am afraid that this is a misunderstanding. The Second Law tells that the entropy increases in the isolated system. This is not the case with life on the Earth, as energy comes in and go out. In this case, if to speak of a system not far from the stationary state, Ilya Prigogine has proved that then the production of the entropy should be minimal. However, even this could not be generalized to the case when a system is far from equilibrium (this seems to be case with life on the Earth). Hence it is unlikely that the Second Law could help us when one considers evolution problems. In any case, I would recommend you the works of Ilya Prigogine – he was a great thermodynamicist.

  4. Clément says:

    Dear Evgenii,

    You make a good point. The second law only applies to closed systems. So, we need to consider thermodynamics of open systems (or far from equilibrium). But there is no universally accepted theory in the thermodynamics of open systems (see


  5. I believe that this is a different problem. There is a definitely some trick to define a thermodynamic equation for an open system. Yet, chemical potential makes the trick and it is working pretty well:

    dU = TdS – pdV + Sum_i m_i dn_i

    What problems to you see with that? Provided that we can define a local temperature in the system, this works nicely. We should not forget that thermodynamics is not kinetics and time as such does not belong to the thermodynamic realm.

    The problem with the Universe is of different nature. All extensive functions in the equation above are assumed to be additive. This is the problem.