Experimentation in cosmology: Intervening on the whole universe.

There are many arguments against the possibility of experimenting on the whole universe. This system seems to be too big to be manipulated, it exists in only one exemplar and its evolution is a non-repeatable process. In this paper, I claim that we can nonetheless talk about experimentation in cosmology if we use Woodward's non-anthropocentric notion of intervention. However, Woodward and other interventionists argued that an intervention was necessarily an exogenous causal process and thus that no intervention on a closed system such as the universe was possible. I discuss their argument and I determine the conditions under which a consistent notion of endogenous intervention on the universe can be defined. Then, I show that there is at least one cosmic phenomenon satisfying these conditions: the photon decoupling. Finally, I draw some conclusions from this analysis regarding a realist approach of cosmology.

Present and future of CosmoLattice.

We discuss the present state and planned updates of CosmoLattice, a cutting-edge code for lattice simulations of non-linear dynamics of scalar-gauge field theories in an expanding background. We first review current capabilities of the code, including the simulation of interacting singlet scalars and of Abelian and non-Abelian scalar-gauge theories. We also comment on new features recently implemented, such as the simulation of gravitational waves from scalar and gauge fields. Secondly, we discuss new extensions of CosmoLattice that we plan to release publicly. On the one hand, we comment on new physics modules, which include axion-gauge interactions φFF̃, non-minimal gravitational couplings φ^2R, creation and evolution of cosmic defect networks, and magneto-hydro-dynamics (MHD). On the other hand, we discuss new technical features, including evolvers for non-canonical interactions, arbitrary initial conditions, simulations in 2+1 dimensions, and higher accuracy spatial derivatives. .

Unveiling the evolution of rotating black holes in loop quantum cosmology.

In this work, we aim to discuss about the evolution of rotating black holes (RBHs) within the context of loop quantum cosmology. Here, the main part of our research work focuses on the impacts of angular momentum based rotating parameter and accretion efficiency on the lifetime of RBHs. Our study reveals that accretion of dark energy would not significantly affect the evolution of RBHs, however higher value of rotating parameter could slightly delay the evaporation times of RBHs. Our analysis also depicts that the maximum value of rotating parameter for evolution of any RBH is 10 - 8 M i 2 , where M i is the formation mass of RBH. Moreover, from our calculation we found that the maximum mass of a presently existing supermassive black hole would be 10 48 g , if it undergoes rotation. Also from astrophysical constraint analysis, we found that there is a greater tendency for formation of black holes in loop quantum cosmology than standard model of cosmology.

Of comets and cosmology in Antonino Saliba's Nuova Figura di tutte le cose of 1582.

Antonino Saliba, a sixteenth century cartographer hailing from the Maltese island of Gozo, published a map in 1582 espousing his cosmology. Its popularity at the time is attested via the multiple editions and copies that were produced in Europe. Numerous sky phenomena, amongst them comets, are portrayed in the map. This study presents a detailed analysis of Saliba's treatment of these phenomena, following the first comprehensive translation of the map's text to English. It elucidates the sources that Saliba used, clarifying and shedding further light on the views he held. Where possible, the comets mentioned by Saliba are identified and explained. Besides showing how Saliba wholly conformed to the Aristotelian and Ptolemaic representation of the world, in which respect he was quite orthodox, it is also shown for the first time that his work is significantly derived from previous and contemporary sources.

Time-Delay Cosmography: Measuring the Hubble Constant and Other Cosmological Parameters with Strong Gravitational Lensing.

Multiply lensed images of a same source experience a relative time delay in the arrival of photons due to the path length difference and the different gravitational potentials the photons travel through. This effect can be used to measure absolute distances and the Hubble constant ( H 0 ) and is known as time-delay cosmography. The method is independent of the local distance ladder and early-universe physics and provides a precise and competitive measurement of H 0 . With upcoming observatories, time-delay cosmography can provide a 1% precision measurement of H 0 and can decisively shed light on the current reported 'Hubble tension'. This manuscript details the general methodology developed over the past decades in time-delay cosmography, discusses recent advances and results, and, foremost, provides a foundation and outlook for the next decade in providing accurate and ever more precise measurements with increased sample size and improved observational techniques.

The Figure of the Staggering Rat: Reading Colonial Outbreak Narratives Against the Grain of "Virus Hunting".

The image of dazed, plague-infected rats coming out of their nests and performing a pirouette in front of the surprised eyes of humans before dying is one well-known to us through Albert Camus's The Plague (1947). This article examines the historical roots of this image and its emergence in French missionary narratives about plague outbreaks in the Chinese province of Yunnan in the 1870s on the eve of the Third Plague Pandemic. Showing that accounts of the "staggering rat" were not meant as naturalist observations of a zoonotic disease, as is generally assumed by historians, but as a cosmological, end-of-the-world narrative with a colonial agenda, the article argues for an approach to historical accounts of epidemics that does not succumb to the current trend of "virus hunting" in the archive, but rather takes colonial outbreak narratives ethnographically seriously.

Modes of the Dark Ages 21 cm field accessible to a lunar radio interferometer.

At redshifts beyond [Formula: see text], the 21 cm line from neutral hydrogen is expected to be essentially the only viable probe of the three-dimensional matter distribution. The lunar far-side is an extremely appealing site for future radio arrays that target this signal, as it is protected from terrestrial radio frequency interference, and has no ionosphere to attenuate and absorb radio emission at low frequencies (tens of MHz and below). We forecast the sensitivity of low-frequency lunar radio arrays to the bispectrum of the 21 cm brightness temperature field, which can in turn be used to probe primordial non-Gaussianity generated by particular early universe models. We account for the loss of particular regions of Fourier space due to instrumental limitations and systematic effects, and predict the sensitivity of different representative array designs to local-type non-Gaussianity in the bispectrum, parametrized by [Formula: see text]. Under the most optimistic assumption of sample variance-limited observations, we find that [Formula: see text] could be achieved for several broad redshift bins at [Formula: see text] if foregrounds can be removed effectively. These values degrade to between [Formula: see text] and 0.7 for [Formula: see text] to [Formula: see text], respectively, when a large foreground wedge region is excluded. This article is part of a discussion meeting issue 'Astronomy from the Moon: the next decades (part 2)'.

Modelling science return from the lunar crater radio telescope on the far side of the moon.

The era following the separation of CMB photons from matter, until the emergence of the first stars and galaxies, is known as the Cosmic Dark Ages. Studying the electromagnetic radiation emitted by neutral hydrogen having the 21 cm rest wavelength is the only way to explore this significant phase in the Universe's history, offering opportunities to investigate essential questions about dark matter physics, the standard cosmological model and inflation. Due to cosmological redshift, this signal is now only observable at frequencies inaccessible from the Earth's surface due to ionospheric absorption and reflection. With the Lunar Crater Radio Telescope (LCRT), we aim to conduct unprecedented measurements of the sky-averaged redshifted signal spectrum in the 4.7-47 MHz band, by deploying a 350 m diameter parabolic reflector mesh inside a lunar crater on the far side of the Moon and suspending a receiver at its focus. This work discusses the feasibility of the LCRT science goals through the development of a science model, with emphasis on post-processing techniques to extract the Dark Ages signal from the galactic foreground dominating the expected raw data. This model can be used to vary critical instrument and mission parameters to understand their effect on the quality of the retrieved signal. This article is part of a discussion meeting issue 'Astronomy from the Moon: the next decades (part 2)'.

Astronomy from the moon in the next decades: from exoplanets to cosmology in visible light and beyond.

We look at what astronomy from the Moon might be like over the next few decades. The Moon offers the possibility of installing large telescopes or interferometers with instruments larger than those on orbiting telescopes. We first present examples of ambitious science cases, in particular ideas that cannot be implemented from Earth. After a general review of observational approaches, from photometry to high contrast and high angular resolution imaging, we propose as a first step a 1-metre-class precursor and explore what science can be done with it. We add a proposal to use the Earth-Moon system to test the quantum physics theory. This article is part of a discussion meeting issue 'Astronomy from the Moon: the next decades (part 2)'.

Particle Physics and Cosmology Intertwined.

While the standard model accurately describes data at the electroweak scale without the inclusion of gravity, beyond the standard model, physics is increasingly intertwined with gravitational phenomena and cosmology. Thus, the gravity-mediated breaking of supersymmetry in supergravity models leads to sparticle masses, which are gravitational in origin, observable at TeV scales and testable at the LHC, and supergravity also provides a candidate for dark matter, a possible framework for inflationary models and for models of dark energy. Further, extended supergravity models and string and D-brane models contain hidden sectors, some of which may be feebly coupled to the visible sector, resulting in heat exchange between the visible and hidden sectors. Because of the couplings between the sectors, both particle physics and cosmology are affected. The above implies that particle physics and cosmology are intrinsically intertwined in the resolution of essentially all of the cosmological phenomena, such as dark matter and dark energy, and in the resolution of cosmological puzzles, such as the Hubble tension and the EDGES anomaly. Here, we give a brief overview of the intertwining and its implications for the discovery of sparticles, as well as the resolution of cosmological anomalies and the identification of dark matter and dark energy as major challenges for the coming decades.

Conformal methods in mathematical cosmology.

When he first introduced the notion of a conformal boundary into the study of asymptotically empty space-times, Penrose noted that the boundary would be null, space-like or time-like according as the cosmological constant [Formula: see text] was zero, positive or negative. While most applications of the idea of a conformal boundary have been to the zero-[Formula: see text], asymptotically Minkowskian case, there also has been work on the non-zero cases. Here, we review work with a positive [Formula: see text], which is the appropriate case for cosmology of the universe in which we live. This article is part of a discussion meeting issue 'At the interface of asymptotics, conformal methods and analysis in general relativity'.