The Sunny Spot | Sunny Shell speaking with guest, Ethan Siegel. Dr. Ethan Siegelâs discussions often emphasize the broader implications of habitable zones, inâŠ
Even Albert Einstein himself didnât believe weâd be able to detect gravitational waves from the merger of two black holes.
Researchers have confirmed the presence of an intermediate-mass black hole in the core of Omega Centauri, a cluster that once formed the heart of a separate galaxy. This finding enhances our understanding of black hole evolution and galaxy dynamics. (Artistâs concept.) Credit: SciTechDaily.com.
Researchers confirmed an intermediate-mass black hole in Omega Centauriâs center, supporting theories of its origin as a distinct galaxy core merged with the Milky Way.
Continue reading “Omega Centauri: A Galaxy Core Frozen in Time Reveals Its Black Hole” »
Discover Saganâs unique blend of scientific curiosity and philosophical introspection, as he seamlessly navigates the realms of cosmology and the human condition.
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Continue reading “Why Humanity Needs Science, not Religion | Carl Sagan” »
Dive into the world of tachyons, the elusive particles that might travel faster than light and hold the key to understanding dark matter and the universeâs expansion. Join us as we explore groundbreaking research that challenges our deepest physics laws and hints at a universe far stranger than we ever imagined. Donât miss out on this thrilling cosmic journey!
Chapters:
00:00 Introduction.
00:39 Racing Beyond Light.
03:26 The Tachyon Universe Model.
05:57 Beyond Cosmology: Tachyonsâ Broader Impact.
08:31 Outro.
08:44 Enjoy.
Continue reading “Faster Than Light: New Dark Matter Findings Challenge Classical Physics” »
In late 2019 the previously unremarkable galaxy SDSS1335+0728 suddenly started shining brighter than ever before. To understand why, astronomers have used data from several space and ground-based observatories, including the European Southern Observatoryâs Very Large Telescope (ESOâs VLT), to track how the galaxyâs @brightness has varied. In a study out today, they conclude that they are witnessing changes never seen before in a galaxy â likely the result of the sudden awakening of the massive black hole at its core.
âImagine youâve been observing a distant galaxy for years, and it always seemed calm and inactive,â says Paula SĂĄnchez SĂĄez, an astronomer at ESO in Germany and lead author of the study accepted for publication in Astronomy & Astrophysics. âSuddenly, its [core] starts showing dramatic changes in brightness, unlike any typical events weâve seen before.â This is what happened to SDSS1335+0728, which is now classified as having an âactive galactic nucleusâ (AGN) â a bright compact region powered by a massive black hole â after it brightened dramatically in December 2019 [1].
Some phenomena, like supernova explosions or tidal disruption events â when a star gets too close to a black hole and is torn apart â can make galaxies suddenly light up. But these brightness variations typically last only a few dozen or, at most, a few hundreds of days. SDSS1335+0728 is still growing brighter today, more than four years after it was first seen to âswitch onâ. Moreover, the variations detected in the galaxy, which is located 300 million light-years away in the constellation Virgo, are unlike any seen before, pointing astronomers towards a different explanation.
A team of scientists used NASAâs James Webb Space Telescope to parse the composition of the Crab Nebula, a supernova remnant located 6,500 light-years away in the constellation Taurus. With the telescopeâs MIRI (Mid-Infrared Instrument) and NIRCam (Near-Infrared Camera), the team gathered data that is helping to clarify the Crab Nebulaâs history.
The Crab Nebula is the result of a core-collapse supernova from the death of a massive star. The supernova explosion itself was seen on Earth in 1,054 CE and was bright enough to view during the daytime. The much fainter remnant observed today is an expanding shell of gas and dust, and outflowing wind powered by a pulsar, a rapidly spinning and highly magnetized neutron star.
The Crab Nebula is also highly unusual. Its atypical composition and very low explosion energy previously have been explained by an electron-capture supernova â a rare type of explosion that arises from a star with a less-evolved core made of oxygen, neon, and magnesium, rather than a more typical iron core.
Katie Mack, Perimeter Instituteâs Hawking Chair in Cosmology and Science Communication, takes us on journey through time by exploring the cosmic microwave background (CMB), the faint glow from the Big Bang.
The CMB shows us the universe as it was 13.8 billion years ago, revealing secrets about itsâŠ
Continue reading “Cosmic Microwave Background (CMB) Explained | Cosmology 101 Episode 2” »
Wormholes, a captivating theoretical concept, offer a potential shortcut through space and timeâa celestial tunnel connecting distant points through the intricate fabric of space-time. The inception of this idea dates all the way back to 1935 when Albert Einstein and Nathan Rosen proposed the concept of a wormhole, also known as an Einstein-Rosen bridge, as a unique solution within the framework of Einsteinâs General Relativity(GR). The hypothetical existence of wormholes carries profound implications for space travel, such as the ability to traverse vast cosmic distances in remarkably short durations, and exploring their properties and implications could provide important information about the structure of space-time itself.
Furthermore, being closely linked to other perplexing cosmic phenomena, such as black holes, dark matter, and the enigmatic event known as the Big Bangâthe cosmic genesis that set our universe into motionâwormholes have the potential to provide insights into these cosmic puzzles and deepen our understanding of the origin of the universe. Additionally, investigating wormholes could help bridge the gap between GR and quantum mechanics, which is currently one of the most important problems in theoretical physics.
Inspired by this, a team of researchers, led by Dr. P.K. Sahoo in collaboration with Mr. Zinnat Hassan from the Department of Mathematics at the Hyderabad Campus of Birla Institute of Technology (BITS) Pilani, recently delved into the investigation of wormholes. They focused on the modified teleparallel gravity framework with conformal symmetry within the context of non-commutative geometry. The primary objective of their research was to shed light on the specific conditions required for the existence of wormholes within the above framework. âThe study of wormholes within the context of f(Q) symmetric teleparallel gravity with conformal symmetry under non-commutative geometry represents a sophisticated and specialized area of research in the field of theoretical physics and cosmology,â says Dr. Sahoo. Their findings were published in volume 437 of the journal Annals of Physics in February 2022.
Numerous open questions in gravity theory become apparent from observations in cosmology, such as the cosmic microwave background radiation [1, 2, 3, 4, 5, 6], the large scale structure [7, 8], gravitational waves [9, 10] and supernovae [11]. In order to describe these observations, one needs to study the evolution of both the universe as a whole, modeled by a homogeneous and isotropic background geometry and matter distribution, as well as perturbations of this background. A thorough understanding of such cosmological perturbations and their dynamics imposed by the gravitational interaction is therefore an important necessity for describing and explaining the modern observations in cosmology.
Cosmological perturbations in gravity have been studied for a long time, starting with the case of (pseudo-)Riemannian spacetime geometry, which is employed by the standard formulation of general relativity and the most well-known class of its extensions, in which the gravitational interaction is attributed to the curvature of the metric-compatible, torsion-free Levi-Civita connection [,13,14,15]. This task is significantly simplified by the fact by understanding how perturbations transform under gauge transformations, i.e., infinitesimal diffeomorphisms which retain the nature of the spacetime geometry as a small perturbation of a cosmologically symmetric background. From these gauge transformations, one can derive a set of gauge-invariant perturbation variables, which describe the physical information contained in the metric perturbations as well as the perturbations of the matter variables, so that they become independent of the arbitrary gauge choice. The resulting gauge-invariant perturbation theory is one of the cornerstones of modern cosmology [16,17,18,19].
Despite its overwhelming success in describing observations from laboratory scales up to galactic scales, general relativity is challenged by the aforementioned open questions, as well as the open question how it can be reconciled with quantum theory. This situation motivates the study of modified gravity theories [20]. While numerous theories depart from the standard formulation of general relativity in terms of the curvature of the Levi-Civita connection of a Riemannian spacetime, also other formulations in terms of the torsion or nonmetricity of a flat connection exist and can be used as potential starting points for the construction of modified gravity theories [21, 22]. Focusing on general relativity alone, one finds that these formulations are equivalent in the sense that they lead to field equations which possess the same solutions for the metric irrespective of the geometric properties of the connection under considerationâŠ
