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

5. ExoUniverse Studies: Detectable Presence, Conceptual Features

Khanpour, Mehrdad and Ebrahim Yusofi. Ultra-Dense Regions in the Cosmic Fluid as a Source of Accelerating Universe. arXiv:1709.08612. We note this entry by Islamic Azad University, Iran, astrophysicists both for its considerations of whole universe properties, and as a 21st century inkling of an Islamic recovery, a millennium later, of their grand heritage of wise cosmological philosophy.

By assumption of existence of some ultra-dense regions in the real cosmic fluid, we try to explain the accelerated expansion in both early and present universe. By use of the leading terms in the virial expansion for the equation of state in the FRLW framework, in the form of Pc2=wρ+Bρ2, we are able to solve the Friedmann equations analytically. Then, we obtain alternative relations for the energy density and scale factor evolution that will coincide with the conventional result in the non-virial limit of cosmic fluid. Also, the model is able to justify the quantum foam-like regions in the very early universe before the cosmic inflation. (Abstract)

Langhoff, Kevin, et al. The Multiverse in an Inverted Island. arXiv:2016.05271. In the last two decades we have learned a lot about the origin of spacetime in quantum gravity. (1) We cite this entry by UC Berkeley physicists including Yasunori Nomura, Director of the Berkeley Center for Theoretical Physics, as a example of 21st century collaborative advances which now seem able to consider and quantify an infinite expanse of spatial and temporal macro-cosmoses. We also note that everyone in the 87 references is a man. But if we might shift to a bicameral, philoSophia view, and a consequent phenomenal, self-creative organic genesis, then we inquisitive Earthlings, one and all, can gain an micro-cosmic functional significance by virtue of such achievements

We study the redundancies in the global spacetime description of the eternally inflating multiverse using the quantum extremal surface prescription. We argue that a sufficiently large spatial region in a bubble universe has an entanglement island surrounding it. Consequently, the semiclassical physics of the multiverse can be fully described by the fundamental degrees of freedom associated with certain finite spatial regions. The island arises due to mandatory collisions with collapsing bubbles.. The emergence of the island and the resulting reduction of independent degrees of freedom provides a regularization of infinities which caused the cosmological measure problem. (Abstract excerpt)

Lee, Gain. et al. Understanding the Formation and Evolution of Dark Galaxies in a Simulated Universe. arXiv:2401.07007. We record this paper by Korean astrophysicists as a 2024 example on this site of the current reach and depth of our Earthuman collaborative intelligence. By a philoSophia view, it seems that we Earthlings have innate abilities to carry out a vital task to numerically and textually quantify, describe, record and affirm an ecosmic existence and futurity. As newly enhanced by AI deep neural learning methods, this worldwide project is in early planning stages. In this subject regard, it seems that our individual and collective faculties, truly a global work space, can imagine, study and conjure whole universes. Whomever are we all to be able to do this?

We study the formation and evolution of dark galaxies using the IllustrisTNG cosmological hydrodynamical simulation. We find that at the present epoch (z=0), dark galaxies are located in void regions without star-forming gas. Our results suggest that dark galaxies tend to be formed in less dense regions, and could not form stars because of heating from cosmic reionization. This study based on numerical simulations can provide important hints for validating dark galaxy candidates in observations and for constraining galaxy formation models. (Excerpts)

Li, Changhong, et al. Big Bounce Genesis. arXiv:1403.5625. This model of cosmological origins by way of serially expiring and reinflating universes has been a theoretical option for some time. It was updated in the mid 2000s by the McGill University coauthor Robert Brandenberger, and now receives a further finesse with Li and Yeuk-Kwan Cheung of Nanjing University. For companion papers see The Matter Bounce Alternative to Inflationary Cosmology by RB at 1206.4196, second Abstract, Bouncing Cosmologies: Progress and Problems at 1603.05834, Big Bounce Genesis and Possible Experimental Tests at 1611.04027, and Tracing Primordial Black Holes in Nonsingular Bouncing Cosmology at 1609.02571. A natural philosophy view wonders how fantastic is it that collaborative human beings can begin to quantify and contemplate entire cosmoses. Surely there must be a significance and purpose for we peoples to be able to learn this.

We report on the possibility to use dark matter particle's mass and its cross section as a smoking gun signal of the existence of a Big Bounce at the early stage in the evolution of our currently observed universe. A model independent study of dark matter production in the pre-bounce contraction and the post-bounce expansion epochs of the bounce universe reveals a new venue for achieving the observed relic abundance of our present universe, in which a significantly smaller amount of dark matter with a smaller cross section -- as compared to the prediction of Standard Cosmology -- is produced and carries the information about the bounce universe evolution. Once the values of dark matter mass and cross section are obtained by direct detection in laboratories, this alternative route becomes a signature of the bounce universe scenario. (Abstract)

A bouncing cosmology with an initial matter-dominated phase of contraction during which scales which are currently probed with cosmological observations exit the Hubble radius provides a mechanism alternative to inflation for producing a nearly scale-invariant spectrum of cosmological perturbations. In this review article I first discuss the evolution of cosmological fluctuations in the matter bounce scenario, and then discuss various attempts at realizing such a scenario. (RB Abstract)

Linde, Andrei. A Brief History of the Multiverse. arXiv:1512.01203. The Russian-American physicist, based at Stanford University for many years, provides a succinct, fascinating chronicle of inflationary theories and the string-multiverse scenario since their 1980s advent. I had the privilege of hearing Linde’s first public lecture in the US in September 1983 at Harvard University about fractally self-reproducing bubble cosmoses. This conceptual model has been refined with many colleagues, especially Alan Guth, his wife Renate Kallosh, Alexei Starobinsky and others, to this day. Search all these names for more postings. In fact, the model has held up well over three decades, lately informed by BICEPS project findings. And again it amazes that collaborative human beings on an infinitesimal world can achieve such infinite imaginations. As Russia and America still confront each other, might we at last think to ask for what phenomenal purpose and discovery can we peoples do this.

Linde, Andrei. Universe or Multiverse?. carnegiescience.edu/events/lectures/universe-or-multiverse. A Carnegie Institution for Science, Washington public lecture to be given on June 27, 2019 by the Russian-American Stanford University astrophysicist and 1980s co-founder with Alan Guth of inflationary theory. (Search AL for recent verifications via the Planck satellite and more.) We also cite for its notable perception of multiple cosmoses. (I heard Andrei give his first public lecture in the US in 1983 at Harvard where he used overheads of fractal bubbling cosmoses, so he remains much on message.)

Cosmological observations show that on the largest scales accessible to our telescopes, the universe is very uniform, and the same laws of physics operate in all the parts of it that we can see. Rather paradoxically, the theory that explains this uniformity also predicts that on extremely large scales, the situation may look totally different. Instead of being a single spherically symmetric balloon, our universe may look like a multiverse—a collection of many different exponentially large balloons with different laws of physics operating in each. In the beginning, this picture looked more like a piece of science fiction than a scientific theory. However, recent developments in inflationary cosmology, particle physics, and string theory provide strong evidence supporting this new cosmological paradigm.

Linde, Andrei and Vitaly Vanchurin. How Many Universes are in the Multiverse? Physical Review D. 81/083525. 2010. Stanford University cosmologists offer mathematical and physical considerations to date about the presence and proliferation of universes. In the 1980s Linde was famously with Alan Guth an original conceiver of an inflationary cosmic origin, which seems to be holding its own by way of the latest Planck space telescope. A further interest here is an emphatic endorsement of the need for participant observers to record and bring a cosmos into full existence.

We argue that the total number of distinguishable locally Friedmann universes generated by eternal inflation is proportional to the exponent of the entropy of inflationary perturbations and is limited by the number of e-folds of slow-roll post-eternal inflation. We discuss the possibility that the strongest constraint on the number of distinguishable universes may be related not to the properties of the multiverse but to the properties of observers. (Abstract)

One of the implications of this result is that one can talk about the evolution of the universe only with respect to an observer. In the limit when the mass of the observer vanishes, the rest of the universe freezes in time. In this sense, the number of distinct observable histories of the universe is bounded from above by the total number of the histories that can be recorded by a given observer. (9) Potentially, it may become very important that when we analyze the probability of existence of a universe of a given type, we should be talking about a consistent pair: the universe and an observer who makes the rest of the universe “alive” and the wave function of the rest of the universe time-dependent. (9)

Linder, Eric and David Polarski. The End of Cosmic Growth. arXiv:1810.10547. UC Berkeley and University of Montpellier, France cosmologists proceed to quantify and propose by way of mathematical graphs a past, present and future of this entire universe. We note the achievement in itself, and also how ever fantastic is it that a collaborative species on an infinitesimal globe can in a few decades be able to consider, describe and learn all about such infinite reaches. It would appear that humankinder has some phenomenal cosmic identity and purpose if only me with We could come to our senses.

The growth of large scale structure is a battle between gravitational attraction and cosmic acceleration. We investigate the future behavior of cosmic growth under both general relativity (GR) and modified gravity during prolonged acceleration, deriving analytic asymptotic behaviors and showing that gravity generally loses and growth ends. We also note the `why now' problem is equally striking when viewed in terms of the shut down of growth. For many models inside GR the gravitational growth index γ also shows today as a unique time between constant behavior in the past and a higher asymptotic value in the future. Interestingly, while f(R) models depart in this respect dramatically from GR today and in the recent past, their growth indices are identical in the asymptotic future and past. (Abstract)

Loeb, Abraham. On the Habitability of Our Universe. arXiv:1606.08926. The Harvard astronomer continues his imaginations about intelligent life, cosmoses and human concerns in a posting to appear in a Consolidation of Fine Tuning volume (search). Some 52 pages with 255 references set the scene with regard to early conditions for life, carbon enhanced, metal poor stars, water occurrence and planetary metallicity, an anthropic cosmological constant, and likelihood of life over cosmic time. See also arXiv:1606.08448 by Loeb with Rafael Batista and David Sloan for a companion paper.

Is life most likely to emerge at the present cosmic time near a star like the Sun? We consider the habitability of the Universe throughout cosmic history, and conservatively restrict our attention to the context of "life as we know it" and the standard cosmological model, LCDM. The habitable cosmic epoch started shortly after the first stars formed, about 30 Myr after the Big Bang, and will end about 10 Tyr from now, when all stars will die. We review the formation history of habitable planets and find that unless habitability around low mass stars is suppressed, life is most likely to exist near 0.1 solar mass stars ten trillion years from now. Spectroscopic searches for biosignatures in the atmospheres of transiting Earth-mass planets around low mass stars will determine whether present-day life is indeed premature or typical from a cosmic perspective. (Abstract)

Marosek, Konrad, et al. Cyclic Multiverses. Monthly Notices of the Royal Astronomical Society. Online July, 2016. As the Abstract details, Marosek, with Mariusz Dabrowski and Adam Balcerzak, University of Szczecin Cosmology Group theorists, postulate dynamic cosmoses across infinite space and time by way of singularities bubbling and bouncing in and out of existence. To reflect, in his epic Cosmos series Carl Sagan (1934-1996) notes that his Polish grandfather never left his little hamlet, while his grandson can tour far galaxies. Circa 2016 how fantastic is it that Earthly intellects can expand to multiUniVerse infinities. Surely there must be a reason for phenomenal humanity to be able to comprehend such vistas, some grand discovery relative to the fate and future of the whole self-chosen cosmos.

Using the idea of regularisation of singularities due to the variability of the fundamental constants in cosmology we study the cyclic universe models. We find two models of oscillating and non-singular mass density and pressure ("non-singular" bounce) regularised by varying gravitational constant G despite the scale factor evolution is oscillating and having sharp turning points ("singular" bounce). Both violating (big-bang) and non-violating (phantom) null energy condition models appear. Then, we extend this idea onto the multiverse containing cyclic individual universes with either growing or decreasing entropy though leaving the net entropy constant. In order to get an insight into the key idea, we consider the doubleverse with the same geometrical evolution of the two "parallel" universes with their physical evolution (physical coupling constants c(t) and G(t)) being different. An interesting point is that there is a possibility to exchange the universes at the point of maximum expansion -- the fact which was already noticed in quantum cosmology. (Abstract)

Masaki, Shogo, et al. Anisotropic Separate Universe Simulations. arXiv:2003.10052. Suzuka College, Kyoto University and University of Toyko physicists open the paper by noting that worldwide scientific collaborations now make it possible to theoretically consider entire cosmoses with regard to variable parameters and properties. In a philoSophia view, how fantastic is it that we phenomenal human beings are altogether capable of considering and quantifying a whole universe.

The long-wavelength coherent overdensity and tidal force affect time evolution of cosmic structure formation and therefore clustering observables through the mode coupling. In this paper we develop an "anisotropic" separate universe (SU) simulation technique to simulate large-scale structure formation. We modify the TreePM N-body simulation code to implement the anisotropic SU simulations, and then study the "response" function of matter power spectrum that describes how the matter power spectrum responds to the large-scale tidal effect as a function of wavenumber and redshift for a given global cosmology. We test and validate the SU simulation results from the comparison with the perturbation theory predictions and the results from high-resolution PM simulation. We find that the response function displays characteristic scale dependences over the range of scales down to nonlinear scales, up to k ~ 6 h/Mpc. (Abstract)

Ord, Toby. The Edges of Our Universe. arXiv:2104.01191. We cite this entry by an Oxford University, Future of Humanity Institute research philosopher as an example of collaborative human abilities which can lately quantify and describe even this entire trillion galaxy, solar system expanse. It is current work as this across the parsecs which can be seen to give microcosmic Earthlings a central, participatory relevance. That is to say phenomenal people in community seem to have a vital, ingrained function of importance to the whole panorama.

This paper explores the fundamental causal limits on how much of the universe we can observe or affect. It distinguishes four principal regions: the affectable universe, the observable universe, the eventually observable universe, and the ultimately observable universe. It then shows how these (and other) causal limits set physical bounds on what spacefaring civilisations could achieve over the longterm future. (Abstract)

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