Lifeboat Foundation

String theory proposes that all particles and forces are made of tiny, vibrating strings, which form the fundamental building blocks of the universe. This framework offers a potential solution to the long-standing paradoxes surrounding black holes, such as their singularities—infinitely tiny points where the laws of physics break down—and the Hawking radiation paradox, which questions the fate of information falling into black holes.

Fuzzballs replace the singularity with an ultra-compressed sphere of strings, likened to a neutron star’s structure but composed of subatomic strings instead of particles. While the theory remains incomplete, its implications are significant, offering an alternative explanation for phenomena previously attributed to black holes.

To differentiate between black holes and fuzzballs, researchers are turning to gravitational waves—ripples in spacetime caused by cosmic collisions. When black holes merge, they emit specific gravitational wave signatures that have so far aligned perfectly with Einstein’s general relativity. However, fuzzballs might produce subtle deviations from these patterns, providing a way to confirm their existence.

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Written by ‪@PaulMSutter‬
Check out his fantastic YouTube channel and podcast for more:
/ paulmsutter.
https://www.pmsutter.com/shows/askasp…
And his books which inspired this video: https://www.pmsutter.com/books.

A huge thanks to our Ho’oleilana Patreon supporters — James Keller and Unpunnyfuns.

Continue reading “What Is The Ultimate Cosmic Limit?” »

How and where particles are accelerated in the jets of supermassive black holes has been a long-standing mystery.

Astronomers have discovered a pair of young stars near the supermassive black hole at the heart of our galaxy. Studying them can offer a rare glimpse into how stars can endure — at least briefly — the immense gravity exerted by such cosmic behemoths.

Sleeping after eating!

Which brings us to the big question: what about gravity?

This is something where we can’t be certain, as gravitation remains the only known force for which we don’t have a full quantum description. Instead, we have Einstein’s general relativity as our theory of gravity, which relies on a purely classical (i.e., non-quantum) formalism for describing it. According to Einstein, spacetime behaves as a four-dimensional fabric, and it’s the curvature and evolution of that fabric that determines how matter-and-energy move through it. Similarly it’s the presence and distribution of matter-and-energy that determine the curvature and evolution of spacetime itself: the two notions are linked together in an inextricable way.

Now, over on the quantum side, our other fundamental forces and interactions have both a quantum description for particles and a quantum description for the fields themselves. All calculations performed within all quantum field theories are calculated within spacetime, and while most of the calculations we perform are undertaken with the assumption that the underlying background of spacetime is flat and uncurved, we can also insert more complex spacetime backgrounds where necessary. It was such a calculation, for example, that led Stephen Hawking to predict the emission of the radiation that bears his name from black holes: Hawking radiation. Combining quantum field theory (in that case, for electromagnetism) with the background of curved spacetime inevitably leads to such a prediction.

Patreon: https://www.patreon.com/seanmcarroll.
Blog post with audio player, show notes, and transcript: https://www.preposterousuniverse.com/podcast/2023/06/19/240-…-universe/

It’s somewhat amazing that cosmology, the study of the universe as a whole, can make any progress at all. But it has, especially so in recent decades. Partly that’s because nature has been kind to us in some ways: the universe is quite a simple place on large scales and at early times. Another reason is a leap forward in the data we have collected, and in the growing use of a powerful tool: computer simulations. I talk with cosmologist Andrew Pontzen on what we know about the universe, and how simulations have helped us figure it out. We also touch on hot topics in cosmology (early galaxies discovered by JWST) as well as philosophical issues (are simulations data or theory?).

Continue reading “Mindscape 240 | Andrew Pontzen on Simulations and the Universe” »

Almost 300 binary mergers have been detected so far, indicated by their passing gravitational waves. These measurements from the world’s gravitational wave observatories put constraints on the masses and spins of the merging objects such as black holes and neutron stars, and in turn this information is being used to better understand the evolution of massive stars.

Thus far, these models predict a paucity of black hole binary pairs where each black hole has around 10 to 15 times the mass of the sun. This “dip or mass gap” in the mass range where black holes seldom form depends on assumptions made in the models; in particular, the ratio of the two masses in the binary.

Now a new study of the distribution of the masses of existing black holes in binaries finds no evidence for such a dip as gleaned from the gravitational waves that have been detected to date. The work is published in The Astrophysical Journal.

Astronomers have discovered a massive dormant black hole from the early universe, just 800 million years after the Big Bang, using the James Webb Space Telescope.

This black hole, with a mass 400 million times that of our Sun, challenges existing models of black hole growth due to its size and low accretion rate.

Unprecedented black hole size and behavior.