Millisecond Pulsars as Standards: Timing, positioning and communication
Millisecond pulsars (MSPs) have a great potential to set standards in timekeeping, positioning and metadata communication.
physics.pop-ph↗
arXiv subjects
Clement Vidal
Publications and source records attributed to Clement Vidal.
Pulsar Positioning System: A quest for evidence of extraterrestrial engineering
Pulsars have at least two impressive applications. First, they can be used as highly accurate clocks, comparable in stability to atomic clocks; secondly, a small subset of pulsars, millisecond X-ray pulsars, provide all the necessary ingredients for a passive galactic positioning system. This is known in astronautics as X-ray pulsar-based navigation (XNAV). XNAV is comparable to GPS, except that it operates on a galactic scale. I propose a SETI-XNAV research program to test the hypothesis that this pulsar positioning system might be an instance of galactic-scale engineering by extraterrestrial beings (section 4). The paper starts by exposing the basics of pulsar navigation (section 2), continues with a critique of the rejection of the extraterrestrial hypothesis when pulsars were first discovered (section 3). The core section 4 proposes lines of inquiry for SETI-XNAV, related to: the pulsar distribution and power in the galaxy; their population; their evolution; possible pulse synchronizations; pulsar usability when navigating near the speed of light; decoding galactic coordinates; directed panspermia; and information content in pulses. Even if pulsars are natural, they are likely to be used as standards by ETIs in the galaxy (section 5). I discuss possible objections and potential benefits for humanity, whether the research program succeeds or not (section 6).
physics.pop-ph↗
Organized Complexity: is Big History a Big Computation?
The concept of "logical depth" introduced by Charles H. Bennett (1988) seems to capture, at least partially, the notion of organized complexity, so central in big history. More precisely, the increase in organized complexity refers here to the wealth, variety and intricacy of structures, and should not be confused with the increase of random complexity, formalized by Kolmogorov (1965). If Bennett is right in proposing to assimilate organized complexity with "computational content", then the fundamental cause of the increase of complexity in the universe is the existence of computing mechanisms with memory, and able to cumulatively create and preserve computational contents. In this view, the universe computes, remembers its calculations, and reuses them to conduct further computations. Evolutionary mechanisms are such forms of cumulative computation with memory and we owe them the organized complexity of life. Language, writing, culture, science and technology can also be analyzed as computation mechanisms generating, preserving and accelerating the increase in organized complexity. The main unifying theme for big history is the energy rate density, a metric based on thermodynamics. However useful, this metric does not provide much insight into the role that information and computation play in our universe. The concept of "logical depth" provides a new lens to examine the increase of organized complexity. We argue in this paper that organized complexity is a valid and useful way to make sense of big history. Additionally, logical depth has a rigorous formal definition in theoretical computer science that hints at a broader research program to quantify complexity in the universe. Keywords: organized complexity, Kolmogorov complexity, logical depth, big history, cosmic evolution, evolution, complexity, complexification, computation, artificial life, philosophy of information
cs.OH↗
Prime Focus Spectrograph (PFS) for the Subaru Telescope: Overview, recent progress, and future perspectives
PFS (Prime Focus Spectrograph), a next generation facility instrument on the 8.2-meter Subaru Telescope, is a very wide-field, massively multiplexed, optical and near-infrared spectrograph. Exploiting the Subaru prime focus, 2394 reconfigurable fibers will be distributed over the 1.3 deg field of view. The spectrograph has been designed with 3 arms of blue, red, and near-infrared cameras to simultaneously observe spectra from 380nm to 1260nm in one exposure at a resolution of ~1.6-2.7A. An international collaboration is developing this instrument under the initiative of Kavli IPMU. The project is now going into the construction phase aiming at undertaking system integration in 2017-2018 and subsequently carrying out engineering operations in 2018-2019. This article gives an overview of the instrument, current project status and future paths forward.
astro-ph.IM↗
The Beginning and the End: The Meaning of Life in a Cosmological Perspective
Where does it all come from? Where are we going? Are we alone in the universe? What is good and what is evil? The scientific narrative of cosmic evolution demands that we tackle such big questions with a cosmological perspective. I tackle the first question in Chapters 4-6; the second in Chapters 7-8; the third in Chapter 9 and the fourth in Chapter 10. However, where do we start to answer such questions? In Chapters 1-3, I elaborate the concept of worldview and argue that we should aim at constructing comprehensive and coherent worldviews. In Chapter 4, I identify seven fundamental challenges to any ultimate explanation. I conclude that our explanations tend to fall in two cognitive attractors, the point or the cycle. In Chapter 5, I focus on the free parameters issue, while Chapter 6 is a critical analysis of the fine-tuning issue. I conclude that fine-tuning is a conjecture and that we need to further study how typical our universe is. This opens a research endeavor that I call artificial cosmogenesis. In Chapter 7, I show the importance of artificial cosmogenesis from extrapolating the future of scientific simulations. I then analyze two other evolutionary explanations of fine-tuning in Chapter 8: Cosmological Natural Selection and the broader scenario of Cosmological Artificial Selection. In Chapter 9, I inquire into the search for extraterrestrials and conclude that some binary star systems are good candidates. Since those putative beings feed on stars, I call them starivores. The question of their artificiality remains open, but I propose a prize to further continue and motivate the scientific assessment of this hypothesis. In Chapter 10, I explore foundations to build a cosmological ethics and conclude that the ultimate good is the infinite continuation of the evolutionary process. Appendix I summarizes my position and Appendix II provides argumentative maps of the entire thesis.
physics.gen-ph↗
Artificial Cosmogenesis: A New Kind of Cosmology
This paper introduces foundations for a new kind of cosmology. We advocate that computer simulations are needed to address two key cosmological issues. First, the robustness of the emergence of complexity, which boils down to ask: "what would remain the same if the tape of the universe were replayed?" Second, the much debated fine-tuning issue, which requires to answer the question: "are complex universes rare or common in the space of possible universes?" We argue that computer simulations are indispensable tools to address those two issues scientifically. We first discuss definitions of possible universes and of possible cosmic outcomes - such as atoms, stars, life or intelligence. This leads us to introduce a generalized Drake-like equation, the Cosmic Evolution Equation. It is a modular and conceptual framework to define research agendas in computational cosmology. We outline some studies of alternative complex universes. However, such studies are still in their infancy, and they can be fruitfully developed within a new kind of cosmology, heavily supported by computer simulations, Artificial Cosmogenesis. The Appendix [section 9] provides argumentative maps of the paper's main thesis. KEYWORDS: artificial cosmogenesis, cosmic evolution, computational cosmology, digital physics, Drake equation, Cosmic Evolution Equation, robustness, fine-tuning, multiverse.
physics.gen-ph↗
Black Holes: Attractors for Intelligence?
The Search for Extra-Terrestrial Intelligence (SETI) has so far been unsuccessful and needs additional methods. We introduce a two-dimensional metric for civilization development, using the Kardashev scale of energy increase and the Barrow scale of inward manipulation. To support Barrow's scale limit, we contend with energetic, societal, scientific, computational, and philosophical arguments that black holes are attractors for intelligence. An application of the two-dimensional metric leads to a simple, consistent and observable hypothesis to test the existence of very advanced civilizations. We suggest that some already observed X-Ray binaries may be unnoticed advanced civilizations, of type KII-Bomega. The appendix provides an argumentative map of the paper's main thesis. KEYWORDS: SETI, black holes, Kardashev scale, Barrow scale, star lifting, XRB
physics.gen-ph↗
Computational and Biological Analogies for Understanding Fine-Tuned Parameters in Physics
In this philosophical paper, we explore computational and biological analogies to address the fine-tuning problem in cosmology. We first clarify what it means for physical constants or initial conditions to be fine-tuned. We review important distinctions such as the dimensionless and dimensional physical constants, and the classification of constants proposed by Levy-Leblond. Then we explore how two great analogies, computational and biological, can give new insights into our problem. This paper includes a preliminary study to examine the two analogies. Importantly, analogies are both useful and fundamental cognitive tools, but can also be misused or misinterpreted. The idea that our universe might be modelled as a computational entity is analysed, and we discuss the distinction between physical laws and initial conditions using algorithmic information theory. Smolin introduced the theory of "Cosmological Natural Selection" with a biological analogy in mind. We examine an extension of this analogy involving intelligent life. We discuss if and how this extension could be legitimated. Keywords: origin of the universe, fine-tuning, physical constants, initial conditions, computational universe, biological universe, role of intelligent life, cosmological natural selection, cosmological artificial selection, artificial cosmogenesis.
physics.gen-ph↗
The Evolution and Development of the Universe
This document is the Special Issue of the First International Conference on the Evolution and Development of the Universe (EDU 2008). Please refer to the preface and introduction for more details on the contributions. Keywords: acceleration, artificial cosmogenesis, artificial life, Big Bang, Big History, biological evolution, biological universe, biology, causality, classical vacuum energy, complex systems, complexity, computational universe, conscious evolution, cosmological artificial selection, cosmological natural selection, cosmology, critique, cultural evolution, dark energy, dark matter, development of the universe, development, emergence, evolution of the universe evolution, exobiology, extinction, fine-tuning, fractal space-time, fractal, information, initial conditions, intentional evolution, linear expansion of the universe, log-periodic laws, macroevolution, materialism, meduso-anthropic principle, multiple worlds, natural sciences, Nature, ontology, order, origin of the universe, particle hierarchy, philosophy, physical constants, quantum darwinism, reduction, role of intelligent life, scale relativity, scientific evolution, self-organization, speciation, specification hierarchy, thermodynamics, time, universe, vagueness.
physics.gen-ph↗
The Future of Scientific Simulations: from Artificial Life to Artificial Cosmogenesis
This philosophical paper explores the relation between modern scientific simulations and the future of the universe. We argue that a simulation of an entire universe will result from future scientific activity. This requires us to tackle the challenge of simulating open-ended evolution at all levels in a single simulation. The simulation should encompass not only biological evolution, but also physical evolution (a level below) and cultural evolution (a level above). The simulation would allow us to probe what would happen if we would "replay the tape of the universe" with the same or different laws and initial conditions. We also distinguish between real-world and artificial-world modelling. Assuming that intelligent life could indeed simulate an entire universe, this leads to two tentative hypotheses. Some authors have argued that we may already be in a simulation run by an intelligent entity. Or, if such a simulation could be made real, this would lead to the production of a new universe. This last direction is argued with a careful speculative philosophical approach, emphasizing the imperative to find a solution to the heat death problem in cosmology. The reader is invited to consult Annex 1 for an overview of the logical structure of this paper. -- Keywords: far future, future of science, ALife, simulation, realization, cosmology, heat death, fine-tuning, physical eschatology, cosmological natural selection, cosmological artificial selection, artificial cosmogenesis, selfish biocosm hypothesis, meduso-anthropic principle, developmental singularity hypothesis, role of intelligent life.
cs.AI↗