Physics

Among the many outreach and communication tools available in our digital era, traditional tools such as exhibitions still hold an important place. The ALICE collaboration is setting up a new exhibition at the experiment's site, as part of the ALICE Visitor Centre. Its goal is to communicate to visitors the physics and the tools and methods used by ALICE. It combines modern technology such as video mapping with real detector items, aiming to fascinate the visitors and give them an immersive experience of a high energy physics experiment. The development process, the messages to be delivered and the choices for the contents and the way of exhibiting them are discussed; and the final design and present status of the project are presented.

The Search for Extraterrestrial Intelligence (SETI) is a research activity that started in the late 1950s, predating the arrival of "Big History" and "Astrobiology" by several decades. Many elements first developed as part of the original SETI narrative are now incorporated in both of these emergent fields. However, SETI still offers the widest possible perspective, since the topic naturally leads us to consider not only the future development of our own society but also the forward trajectories (and past histories) of many other intelligent extraterrestrial forms. In this paper, I present a provocative view of Big History, its rapid convergent focus on our own planet and society, its oversimplified and incomplete view of events in cosmic history, and its limited appreciation of how poorly we understand some aspects of the physical world. Astrophysicists are also not spared - in particular those who wish to understand the nature of the universe in "splendid isolation", only looking outwards and upwards. SETI can help re-expand all of our horizons but the discovery of extraterrestrial intelligence may also require its own practitioners to abandon preconceptions of what constitutes intelligent, sentient, thinking minds.

We currently harness technologies that could shed new light on old philosophical questions, such as whether our mind entails anything beyond our body or whether our moral values reflect universal truth.

Are there parallels between the furthest reaches of our universe, and the foundations of thought, awareness, perception, and emotion? What are the connections between the webs and structures that define both? What are the differences? "As Above As Below" was an exhibition that examined these questions. It consisted of six artworks, each of them the product of a collaboration that included at least one artist, astrophysicist, and neuroscientist. The installations explored new parallels between intergalactic and neuronal networks through media such as digital projection, virtual reality, and interactive multimedia, and served to illustrate diverse collaboration practices and ways to communicate across very different fields.

Thousands of exoplanets have been discovered and the search for life outside Earth is at the forefront of astrophysical research. The planets we observe show a mind-blowing diversity that current theories strive to explain as part of the quest to assess the chances of finding life outside the Earth.

Freeman J. Dyson, a brilliant theoretical physicist and a gifted mathematician, passed away on 28 February 2020 at the age of 96. A vignette of his outstanding contributions to physical sciences, ranging from the subject of quantum electrodynamics to gravitational waves, is provided in this article. Dyson's futuristic ideas concerning the free will of `intelligent life' influencing the remote future of the cosmos with `Eternal Intelligence', Dyson tree, Dyson sphere and so on, have also been discussed briefly.

Fermi's Paradox is the contradiction between the fact that it would seem to be highly probable that there are other technologically advanced species beyond the Earth, and the fact that there is no generally accepted evidence for their existence. Hanson and Bostrom have proposed that there may be a Great Filter, a survival challenge so lethal that it prevents virtually all species from evolving to an advanced stage. This paper argues that the Great Filter would be not one single factor, but rather simply the statistics of survival in an always-dangerous universe. The frequency of species that survive multiple existential threats would likely obey a power law such as Lotka's Law, such that the frequency of survivors would diminish as an inverse power of the number of threats. Since any species that advances to the point at which it is detectable on an interstellar scale likely must survive a large number of existential threats, by Lotka's Law the number of such survivors would be a very small fraction of the candidate species that evolve on various planets. Some sobering implications of this picture are outlined.

Fibonacci numbers and the golden ratio can be found in nearly all domains of Science, appearing when self-organization processes are at play and/or expressing minimum energy configurations. Several non-exhaustive examples are given in biology (natural and artificial phyllotaxis, genetic code and DNA), physics (hydrogen bonds, chaos, superconductivity), astrophysics (pulsating stars, black holes), chemistry (quasicrystals, protein AB models), and technology (tribology, resistors, quantum computing, quantum phase transitions, photonics).

Here, we ask a simple question, i.e. "at what cosmic time, at the earliest, did life first appear in the universe?" Given what we know about the universe today, there may be some partial answers to this question, but much will still have to be left to speculation. If life in general requires stars as its primary energy source and uses elemental building blocks heavier than those initially produced in a Big Bang scenario, first life could have appeared, when the universe was considerably less than 0.1 billion years old. At that time, heavy element producing hypernovae exploded at corresponding redshifts.} z \,\gapprox\,45, significantly higher than commonly assumed ( z≈6 ). The recent discovery of a galaxy at z>9 could provide supporting evidence for the hypothesis of a very much shorter time scale than what is widely believed.

Given the great interest that black holes arouse among non-specialists, it is important to analyse misconceptions related to them. According to the author, the most common misconceptions are that: (1) black holes are formed from stellar collapse; (2) they are very massive; (3) they are very dense; (4) their gravity absorbs everything; and (5) they are black. The objective of this work is to analyse and correct these misconceptions. This article may be useful as pedagogical material in high school physics courses or in introductory courses in undergraduate physics.