Reply to 'A Comment on '"The Far Future of Exoplanet Direct Characterization" - the Case for Interstellar Space Probes'

Reply to A Comment on The Far Future of Exoplanet Direct Characterization - the Case for Interstellar Space Probess by Ian Crawford. The paper The Far Future of Exoplanet Direct Characterization resulted from the collective work of TE-SAT, a team appointed by ESA in 2003 to assess a strategy to find and characterize Terrestrial Exoplanets. The interstellar flight aspect was not part of the TE-SAT work and was added afterward as side remarks in the chapter on {\guillemotleft} The Far Future of Exoplanet Direct Characterization {\guillemotright}. As an introductory general remark, the intention of the paper was not to discourage work on interstellar flight prospective. On the contrary, any advance in this field that makes interstellar travel closer to us is welcome. In the framework of this short reply, the discussion can only be qualitative; it would deserve a full future paper.Comment: Published in Astrobiology 10, 857 (2010). Arxiv.org: 0910.072

The question "Are We Alone?" in different cultures

A survey of the worldwide litterature reveals that the question "Are We Alone in the Universe?" has been formulated only in the western litterature. Here I try to understand why it is so. To investigate this problem it is first necessary to clarify what western culture means.Comment: to appear in The Role of Astronomy in Society and Culture: Proceedings of IAU Symposium No. 260, 2009. D. Valls-Gabaud and A. Boksenberg, ed

Time and the Mind/Body Problem: A Quantum Perspective

The Semiotic Interpretation (SI) of QM pushes further the Von Neumann point of view that `experience only makes statements of this type: an observer has made a certain observation; and never any like this: a physical quantity has a certain value.' The supposition that the observables of a system `possess' objective values is purely idealistic. According to the SI view, the state- vector collapse cannot result from the Schroedinger evolution of a system (even with its environment), but only from the empirical production of a mathematical symbol, irreducible to the quantum level. The production of a symbol always takes some time. Thus the state-vector collapse cannot be instantaneous (Schneider 1994), a specific prediction of the present model. From this interpretation of Quantum Mechanics, the appearances of the body are the result of state-vector collapses of several types, i.e. the production of different kinds of symbols. In fact the universe of symbols is very rich: a symbol can have a conceptual `value' (like in physics and then give rise to a measurement), or other qualitative values (like in many human behaviors). In the latter case, the Semiotic Interpretation of QM gives a way to understand how a mental representation can modify the state of the body.Comment: 17 Pages, Latex, no figures. Invited conference at the `Psycho- analysis and Physics' Meeting, New York, December 1996. In press in American Imago. Also at http://www.obspm.fr/departement/darc/schneider/qm.htm

Measuring the radius and mass of Planet Nine

Batygin and Brown (2016) have suggested the existence of a new Solar System planet supposed to be responsible for the perturbation of eccentric orbits of small outer bodies. The main challenge is now to detect and characterize this putative body. Here we investigate the principles of the determination of its physical parameters, mainly its mass and radius. For that purpose we concentrate on two methods, stellar occultations and gravitational microlensing effects (amplification, deflection and time delay). We estimate the main characteristics of a possible occultation or gravitational effects: flux variation of a background star, duration and probability of occurence. We investigate also additional benefits of direct imaging and of an occultation.Comment: PASP accepte