III. Ecosmos: A Revolutionary Fertile, Habitable, Solar-Bioplanet, Incubator Lifescape

5. ExoUniverse Studies: Detectable Presence, Conceptual Features

Scharpe, Charlie, et al. On Cosmological Low Entropy after the Big Bang: Universal Expansion and Nucleosynthesis. arXiv:2302.03988.. CS, a University of Sydney astronomer, is joined by US colleagues Luke Barnes and Geraint Lewis so to continue their whole scale studies across these widest spacescapes. Along with M. Sandora et al (search), an ecosmic scenario proceeds apace with its own internal self-description, which it seems to require, by virtue of our incredible Earthuman expertise.

We investigate the sensitivity of a universe's nuclear entropy after Big Bang nucleosynthesis (BBN) to variations in both the baryon-to-photon ratio and the temporal evolution of cosmological expansion. We find that, while the post-BBN nuclear entropy is indeed linked to baryogenesis and the Universe's expansion history, the requirement of leftover light elements does not place strong constraints on the properties of these two cosmological processes. (Excerpt)

Siegfried, Tom. The Number of the Heavens: A History of the Multiverse and the Quest to Understand the Cosmos. Cambridge: Harvard University Press, 2019. The senior science writer about physics and information (search) here provides a detailed recount of man’s (some 275 male names in the index, one primary woman Lisa Randell) historic wonderments about our starry raiment. Its compass runs from Aristotle and Atomists to Robert Grosseteste in the 13th century onto Copernicus, Nicholas of Cusa, Newton, Galileo, and company as horizons expanded from a sun and moon. Circa 1900, Alfred Wallace’s cosmos had our solar system at its center. The 20th century went on to reveal a galactic universe, its inflationary origin, temporal nucleosynthesis. By 2000, via quantum, string, and other theories, a wider presence became implied and/or required of multiple cosmoses with widely different, contingent properties. Anthropic explanations whence such parameters can be explained because they permit life and intelligence to appear are duly chronicled. As 2020 nears, if one might turn and reflect, how fantastic is this scenario which aware human beings upon a minute ovoworld have at last come to realize.

Tamm, Martin. The Thermodynamical Arrow and the Historical Arrow. Entropy. Online August, 2017. The University of Stockholm mathematician advances this project by way of reviewing many past studies over the decades by Ilya Prigogine, David Layzer, Mario Castagnino and others within a nascent 2010s scenario of a Combinatorial Multiverse.

In this paper, the relationship between the thermodynamic and historical arrows of time is studied. In the context of a simple combinatorial model, their definitions are made more precise and in particular strong versions (which are not compatible with time symmetric microscopic laws) and weak versions (which can be compatible with time symmetric microscopic laws) are given. This is part of a larger project that aims to explain the arrows as consequences of a common time symmetric principle in the set of all possible universes. However, even if we accept that both arrows may have the same origin, this does not imply that they are equivalent, and it is argued that there can be situations where one arrow may be well-defined but the other is not. (Abstract)

Terasawa, Ryo, et al. Separate universe approach to evaluate nonlinear matter power spectrum for non-flat ΛCDM model. arXiv:2205.10339. We cite this entry by four Japanese cosmologists as an example of how the latest Earthuman science is able to extend its compass to myriad other cosmoses. See also Likelihood Criteria for the Universe by Ezequiel Lopez-Rubio at 2206.0097 for another take.

The spatial curvature of the universe is a fundamental quality that could give a link to its early physics. We develop a method to compute the nonlinear matter power spectrum for "non-flat" ΛCDM models using the separate universe (SU) ansatz whence the curvature of structure formation is equivalent to that of long-wavelength density fluctuation. We find that the emulators, those built for flat cosmologies such as EuclidEmulator, can predict the non-flat P(k) with least degradation. (Excerpt)

In physics and mathematics, an ansatz is an educated guess or an additional assumption made to help solve a problem, and which may later be verified to be part of the solution by its results.

Trivedi, Oem and Maxim Khlopov. On rips and cosmological singularities in a universe merging with baby universes. arXiv:2401.13251. We record this entry by Ahmedabad University, India and Southern Federal University, Russia astroscientists as Earthuman abilities have now become able to achieve mathematical conceptions of entire, unitary cosmoses. In consideration, they seem to be engaged in interactions with other multiversal entities as each spatially and temporally bubble in and out of existence. I recall seeing Andrei Linde in 1983 at Harvard present this very scenario which he saw as taking on a fractal scale. Some four decades later, our global theoretic and instrumental collaborations can verify these far flung vistas. See also The long freeze: an asymptotically static universe from holographic dark energy by Oem Trivedi and Robert J. Scherrer at arXiv:2409.11420.

Understanding the late-time acceleration of the universe and its subtleties is one of the biggest mysteries in cosmology. Recently an interesting approach to explaining the late time acceleration has been put forward, where the expansion of the universe is driven by mergers with other "baby" universes by way of new observational data. In this work we examine various rip scenarios and other future cosmological singularities in such a "multiversal" scenario.

Wainwright, Carroll, et al. Simulating the Universe(s): From Cosmic Bubble Collisions to Cosmological Observables with Numerical Relativity. Journal of Cosmology and Astroparticle Physics. 03/030, 2014. As the title extols, physicists from UC, Santa Cruz, Perimeter Institute, University College London, and Long Island University, including Hiranya Peiris and Anthony Aguirre, contribute to our collective transformation of cosmos into consciousness. Might we all ask at some point what is the human phenomenon, why can thought span and learn such vistas, what great discovery does the universe want us to make?

The theory of eternal inflation in an inflation potential with multiple vacua predicts that our universe is one of many bubble universes nucleating and growing inside an ever-expanding false vacuum. The collision of our bubble with another could provide an important observational signature to test this scenario. We develop and implement an algorithm for accurately computing the cosmological observables arising from bubble collisions directly from the Lagrangian of a single scalar field. We first simulate the collision spacetime by solving Einstein's equations, starting from nucleation and ending at reheating. We then calculate the comoving curvature perturbation in an open Friedmann-Robertson-Walker universe, which is used to determine the temperature anisotropies of the cosmic microwave background radiation. We characterize observational predictions by computing the probability distributions over four phenomenological parameters which capture these intrinsic and model uncertainties. This represents the first fully-relativistic set of predictions from an ensemble of scalar field models giving rise to eternal inflation, yielding significant differences from previous non-relativistic approximations. (Abstract excerpts)

Wilczek, Frank. Multiversality. Classical and Quantum Gravity. 30/193001, 2013. Also posted at arXiv:1307.7376. The MIT physicist and 2004 Nobel laureate offers a succinct overview of an evident, mathematically legible, realm of myriad variable cosmoses. The main theoretical exercise involves an Inflationary Axion Cosmology, not easily defined, which Wilczek and colleagues such as Max Tegmark have conjured for some years. See their arXiv:0807.1726 for a review. His latest book, A Beautiful Question: Finding Nature’s Deep Design (2015), imagines how such an intrinsic presence across this raiment might be fruitfully discerned.

Valid ideas that physical reality is vastly larger than human perception of it, and that the perceived part may not be representative of the whole, exist on many levels and have a long history. After a brief general inventory of those ideas and their implications, I consider the cosmological "multiverse" much discussed in recent scientific literature. I review its theoretical and (broadly) empirical motivations, and its disruptive implications for the traditional program of fundamental physics. I discuss the inflationary axion cosmology, which provides an example where firmly rooted, plausible ideas from microphysics lead to a well-characterized "mini-multiverse" scenario, with testable phenomenological consequences. (Abstract)

Wood, Charlie. Pondering the Bits that Build Space-Time and Brains. Quanta. April 20, 2022. The entry is at once a lifetime profile of the University of Pennsylvania polyphysicst VijaY Balasubramanain, and a wide survey of theoretical frontier imaginations. In addition, he directs a second research group at Penn that studies how the world’s physical features may have sculpted the brain via information and computation as a natural language. For examples of his current, collegial work see Entanglement between Two Gravitating Universes at arXiv:2104.13383 and See Spin Structures and Baby Universes at 2007.04333. Into the 2020s, it seems to be newly accessible to consider, quantify and play with whole cosmoses.

In 1989, the renowned physicist John Wheeler proposed a radical new way to think about the universe. Quantum particles may shape-shift and disappear, but we can always count on information. Wheeler speculated that bits of information could be the fundamental ingredient of reality. Every physical quantity, every it, derives an ultimate significance from bits, binary yes-or-no indications, he wrote in an essay envisioning an “it from bit” cosmos. (quote)

Wood, Charlie. Why This Universe? A New Calculation Suggest Our Cosmos is Typicall. Quanta. November 17,, 2022. A science writer surveys the latest conjectures about what kind of spatial and temporal environs we Earthlings may actually find ourselves. As a gloss, our scientific scenario this far may be legitimate due to a new array of physical and energetic features. Latham Boyle, Perimeter Institute and Neil Turok, its once director and now at the University of Edinburgh post novel theoretical reasons, which cast back to the 1970s, as to why this is the phenomenal case. See, for example, their Thermodynamic Solution of the Homogeneity, Isotropy and Flatness Puzzles. (arXiv:2210.01142) and The Big Bang as a Mirror: A Solution of the Strong CP Problem (2208.10396) papers.

Two physicists have calculated that the universe has a higher entropy — and is therefore more likely — than alternative possible universes. The calculation is “an answer to a question that is yet to be fully understood.” The properties of our universe — smooth, flat, just a pinch of dark energy — are what we should expect to see, according to a new calculation.

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