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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Black hole | 13/13 | https://en.wikipedia.org/wiki/Black_hole | reference | science, encyclopedia | 2026-05-05T13:31:52.244381+00:00 | kb-cron |
While there is a strong case for supermassive black holes, the dividing line between lighter black holes and neutron stars relies on theories of extremely dense matter. Direct observational tests are not available: objects observed to have mass higher than the predictions for neutron stars are assumed to be black holes. Recent evidence from gravitational wave events suggests modifications of these theories may be needed. New exotic phases of matter could allow other kinds of massive objects. Quark stars would be made up of quark matter and supported by quark degeneracy pressure, a form of degeneracy pressure even stronger than neutron degeneracy pressure. This would halt gravitational collapse at a higher mass than for a neutron star. Even stronger stars called electroweak stars would convert quarks in their cores into leptons, providing additional pressure to stop the star from collapsing. If, as some extensions of the Standard Model posit, quarks and leptons are made up of the even-smaller fundamental particles called preons, a very compact star could be supported by preon degeneracy pressure. While none of these hypothetical models can explain all of the observations of stellar black hole candidates, a Q star is the only alternative which could significantly exceed the mass limit for neutron stars and thus provide an alternative for supermassive black holes. A few theoretical objects have been conjectured to match observations of astronomical black hole candidates identically or near-identically, but which function via a different mechanism. A dark energy star would convert infalling matter into vacuum energy; This vacuum energy would be much larger than the vacuum energy of outside space, exerting outwards pressure and preventing a singularity from forming. A black star would be gravitationally collapsing slowly enough that quantum effects would keep it just on the cusp of fully collapsing into a black hole. A gravastar would consist of a very thin shell and a dark-energy interior providing outward pressure to stop the collapse into a black hole or formation of a singularity; It could even have another gravastar inside, called a 'nestar'.
== In fiction ==
The concept of black holes have inspired artists as well as scientists. In her book Conjuring the Void: the Art of Black Holes, Lynn Gamwell used black holes as an example to explore how art and science interact, considering the application of art to create scientific visualizations and the impact of scientific ideas on art concepts like darkness. Some science fiction films have incorporated relativity into their black hole visualizations, leading to results similar to images derived from the Event Horizon Telescope. Fictional treatments of black holes are also used as a mechanism for teaching science. Black holes have been portrayed in science fiction in a variety of ways. Even before the advent of the term itself, objects with characteristics of black holes appeared in stories. In modern day, authors and screenwriters have exploited the relativistic effects of black holes, particularly gravitational time dilation. Black holes have also been appropriated as wormholes or other methods of faster-than-light travel.
== Notes ==
== References ==
== External links ==
Stanford Encyclopedia of Philosophy: "Singularities and Black Holes" by Erik Curiel and Peter Bokulich. ESA's Black Hole Visualization Archived 3 May 2019 at the Wayback Machine Fall Into A Black Hole on Andrew Hamilton's website Black Hole Parameters Calculator Black Hole News from NASA
=== Videos === Black Hole Apocalypse – documentary on NOVA Black Holes Playlist on YouTube from PBS Space Time "Einstein's gravitational waves 'seen' from black holes". BBC News. 11 February 2016. – artistic visualization of gravitational waves from merging black holes Two Black Holes Merge Into One (Based Upon the Signal GW150914) – realistic simulation of merging black holes Plunge Into A Black Hole – 360° NASA simulation and explanation