5 Unpredictable Things Swift Has Studied (and 1 It’s Still Looking For)

Detecting new particles around black holes with gravitational waves

Clouds of ultralight particles can form around rotating black holes. A team of physicists from the University of Amsterdam and Harvard University now show that these clouds would leave a characteristic imprint on the gravitational waves emitted by binary black holes.

Black holes are generally thought to swallow all forms of matter and energy surrounding them. It has long been known, however, that they can also shed some of their mass through a process called superradiance. While this phenomenon is known to occur, it is only effective if new, so far unobserved particles with very low mass exist in nature, as predicted by several theories beyond the Standard Model of particle physics.

Ionizing gravitational atoms When mass is extracted from a black hole via superradiance, it forms a large cloud around the black hole, creating a so-called gravitational atom. Despite the immensely larger size of a gravitational atom, the comparison with sub-microscopic atoms is accurate because of the similarity of the black hole plus its cloud with the familiar structure of ordinary atoms, where clouds of electrons surround a core of protons and neutrons.

In a publication that appeared in Physical Review Letters this week, a team consisting of UvA physicists Daniel Baumann, Gianfranco Bertone, and Giovanni Maria Tomaselli, and Harvard University physicist John Stout, suggest that the analogy between ordinary and gravitational atoms runs deeper than just the similarity in structure. They claim that the resemblance can in fact be exploited to discover new particles with upcoming gravitational wave interferometers.

In the new work, the researchers studied the gravitational equivalent of the so-called ‘photoelectric effect’. In this well-known process, which for example is exploited in solar cells to produce an electric current, ordinary electrons absorb the energy of incident particles of light and are thereby ejected from a material – the atoms ‘ionize’. In the gravitational analogue, when the gravitational atom is part of a binary system of two heavy objects, it gets perturbed by the presence of the massive companion, which could be a second black hole or a neutron star. Just as the electrons in the photoelectric effect absorb the energy of the incident light, the cloud of ultralight particles can absorb the orbital energy of the companion, so that some of the cloud gets ejected from the gravitational atom.

Finding new particles The team demonstrated that this process may dramatically alter the evolution of such binary systems, significantly reducing the time required for the components to merge with each other. Moreover, the ionization of the gravitational atom is enhanced at very specific distances between the binary black holes, which leads to sharp features in the gravitational waves that we detect from such mergers. Future gravitational wave interferometers – machines similar to the LIGO and Virgo detectors that over the past few years have shown us the first gravitational waves from black holes – could observe these effects. Finding the predicted features from gravitational atoms would provide distinctive evidence for the existence of new ultralight particles.

IMAGE…An atom in the sky. If new ultralight particles exist, black holes would be surrounded by a cloud of such particles that behaves surprisingly similar to the cloud of electrons in an atom. When another heavy object spirals in and eventually merges with the black hole, the gravitational atom gets ionized and emits particles just like electrons are emitted when light is shone onto a metal. CREDIT UvA Institute of Physics

Godzilla 2019

炎麒-Enki-

Originally a Twitter Thread, with the help of Thread Reader

Baldolino Calvino🏳️‍🌈🚩🇧🇷✨♻️🌱

Oct 1 • 15 tweets • 4 min read

Fantasy is not science, nor philosophy, and not real (of course). This may seem obvious, but what I am trying to do is creating an exact, non-contradictory definition of fantasy, not as an art genre, but as an object of study. Not by science, but by fantastic natural history.

Fantasy - Wikipedia

"Fantasy is a genre of speculative fiction involving magical elements, typically set in a fictional universe and sometimes inspired by mythology and folklore."

Fantasy, Magic (not meaning prestidigitation), Mythology, and Folklore can be understood as equivalent, overlaping concepts. Wikipedia's entry is mostly tautological, circular, thus.

However, this is an article about the artistic genre, and one could say that it refers to art expression (written, musical, cinematic, other) that uses these references. This is enough for this use case, but we do not advance in an objective conceptualization of fantasy.

Fantasy (psychology) - Wikipedia

"(...) fantasy is a broad range of mental experiences, mediated by the faculty of imagination in the human brain, and marked by an expression of certain desires through vivid mental imagery."

This entry about the concept of fantasy in psychology gives a more elaborared view of it. However, what differentiates fantasy from other instances of human creativjty? The article continues: "Fantasies are associated with scenarios that are absolutely impossible."

Wikipedia's entry on Fantasy (psychology) does not give any reference to this concept, and proceeds listing the importance of Fantasy for various theoretical approaches (Freud, Klein, Lacan), or pathologies (narcissistic personality disorder, schizophrenia). It is not unified.

More revealing is Wikipedia's "History of Fantasy" (about the literary genre).

" (...) the supernatural and the fantastic were an element of literature from its beginning. The modern genre is distinguished from tales and folklore (...)"

It makes a clear distintion between ancient myths and folklore, and so-called "modern fantasy", whose first explicit representant was Scottish author George MacDonald in the late XIX century, with his novels "The Princess and the Goblin" and "Phantastes".

Important precursors were Dickens, Thackeray, Andersen, Ruskin, Morris. And MacDonald's work enormously influenced Tolkien and Lewis. One key word in this historic description of Fantasy is "speculative". And a defining characteristic of modern fantasy is the "fantasy world".

Distinctive differences of modern fantasy are the postulate of a secondary fantasy world apart from reality; fictitious by design; and narratives from a (group of) author(s) with an interpretative aim. Myths or folklore does not have any of these characteristics.

The entry goes on in a detailed description of the development of Fantasy as a literary genre, since writings about tales and legends from Middle Ages. However, one fun example of how medieval mind understood the fantastic can be seen in the novel "Baudolino" by Umberto Eco.

Most of this Wikipedia's entry is based upon https://twitter.com/john_clute and John Grant's https://sf-encyclopedia.com/fe/, published in 1997, and fully available on the internet.

More to come, be patient.

Took this pic some years ago, and love it.

Total Solar Eclipse l April 2024 l U.S. & Canada

Cr. Deran Hall l Rami Ammoun(236) l GabeWasylko l REUTERS l KendallRust l Joshua Intini l Alfredo Juárez l KuzcoKhanda

Bye Twitter! Hello, (again) Tumblr! I am back after years!

this meme but its just horikashi

We are all stardust (Carl Sagan).

Credits: NASA, ESA, CSA, STScI

#spacepic #space #jwst #astronomy #astrophoto #stem #stardust #photography #astrophotography #pilarsofcreation #eaglenebula #serpens #starcreation #stars #newbornstars #science #sciencephotograpy #jameswebspacetelescope #infraredastronomy