*GUEST BIO:* Janna Levin is a theoretical physicist and cosmologist specializing in black holes, cosmology of extra dimensions, topology of the universe, and gravitational waves.
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It’s hard to interpret the strange results of quantum mechanics, though many have tried. Interpretations range from the outlandish—like the multiple universes of Many Worlds, to the almost mundane, like the very mechanical Pilot Wave Theory. But perhaps we’re converging on an answer, because some are arguing that these two interpretations are really the same thing.
The concept of nothing once sparked a 1000-year-long war, today it might explain dark energy and nothingness even has the potential to destroy the universe, explains physicist Antonio Padilla
The blazar BL Lacertae, a supermassive black hole surrounded by a bright disk and jets oriented toward Earth, provided scientists with a unique opportunity to answer a longstanding question: How are X-rays generated in extreme environments like this?
NASA’s IXPE (Imaging X-ray Polarimetry Explorer) collaborated with radio and optical telescopes to find answers. The results, available on the arXiv preprint server and set to be published in the journal Astrophysical Journal Letters, show that interactions between fast-moving electrons and particles of light, called photons, must lead to this X-ray emission.
Scientists had two competing possible explanations for the X-rays, one involving protons and one involving electrons. Each of these mechanisms would have a different signature in the polarization of X-ray light. Polarization is a property of light that describes the average direction of the electromagnetic waves that make up light.
What is time? Speaking time travel, black holes and the remits of science. In this podcast conversation, we speak with Professor David Wilkinson — physicist and author of popular science books on Stephen Hawking to explore the question: can we ever fully understand time through science, or does it open up more mystery?
How do you distinguish a galaxy from a mere cluster of stars? That’s easy, right? A galaxy is a large collection of millions or billion of stars, while a star cluster only has a thousand or so. Well, that kind of thinking won’t get you a Ph.D. in astronomy! Seriously, though, the line between galaxy and star cluster isn’t always clear. Case in point, UMa3/U1.
It’s easy to distinguish galaxies such as Andromeda and the Milky Way. They are large, gravitationally bound, and dominated by dark matter. It’s also easy to distinguish star clusters such as the Pleiades. They are loosely bound star groupings without dark matter. But for a type of small dwarf galaxy known as Ultra-Faint Dwarfs (UFDs) the dividing line gets fuzzy.
UFDs are dominated by dark matter. The mass of the Milky Way, for example, is about 85% dark matter. An ultrafaint dwarf galaxy, however, can have a thousand times more dark matter than luminous matter. This is why they are so faint. Since UFDs often contain some of the oldest stars in the Universe, astronomers love to study them for clues on the origins of galaxies. Which brings us to UMa3/U1.
Ever since general relativity pointed to the existence of black holes, the scientific community has been wary of one peculiar feature: the singularity at the center—a point, hidden behind the event horizon, where the laws of physics that govern the rest of the universe appear to break down completely. For some time now, researchers have been working on alternative models that are free of singularities.
A new paper published in the Journal of Cosmology and Astroparticle Physics, the outcome of work carried out at the Institute for Fundamental Physics of the Universe (IFPU) in Trieste, reviews the state of the art in this area. It describes two alternative models, proposes observational tests, and explores how this line of research could also contribute to the development of a theory of quantum gravity.
“Hic sunt leones,” remarks Stefano Liberati, one of the authors of the paper and director of IFPU. The phrase refers to the hypothetical singularity predicted at the center of standard black holes —those described by solutions to Einstein’s field equations. To understand what this means, a brief historical recap is helpful.
NGC 4945, a beautiful spiral galaxy over 12 million light-years away, hides a ferocious secret: a ravenous black hole at its center. This supermassive beast doesn’t just consume matter — it blasts it back out at incredible speeds, launching winds that escape the galaxy itself. This featured Eu
