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Category: cosmology – Page 183

Last summer, the gravitational wave observatory known as LIGO caught its second-ever glimpse of two neutron stars merging. The collision of these incredibly dense objects — the hulking cores of long-ago supernova explosions — sent shudders through space-time powerful enough to be detected here on Earth. But unlike the first merger, which conformed to expectations, this latest event has forced astrophysicists to rethink some basic assumptions about what’s lurking out there in the universe. “We have a dilemma,” said Enrico Ramirez-Ruiz of the University of California, Santa Cruz.

The exceptionally high mass of the two-star system was the first indication that this collision was unprecedented. And while the heft of the stars alone wasn’t enough to cause alarm, it hinted at the surprises to come.

In a paper recently posted to the scientific preprint site arxiv.org, Ramirez-Ruiz and his colleagues argue that GW190425, as the two-star system is known, challenges everything we thought we knew about neutron star pairs. This latest observation appears to be fundamentally incompatible with scientists’ current understanding of how these stars form, and how often. As a result, researchers may need to rethink years of accepted knowledge.

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One of Albert Einstein’s theory of general relativity’s most fascinating predictions is the possibility of black holes, which are created after a massive star reaches the end of its life and collapses. Supermassive black holes as big as 100,000 or ten billion times the Sun are commonly found at the center of most galaxies.

Those are the biggest form of black holes, but it is also thought that primordial black holes (PBHs) also exist. Unlike the big ones, these tiny black holes emerged in the early cosmos through the gravitational collapse of extraordinarily dense areas.

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The global collaboration that delivered us not one but two pictures of supermassive black holes has now peered into one of the brightest lights in the Universe.

The Event Horizon Telescope (EHT), a telescope array comprising radio antennae around the world, studied a distant quasar named NRAO 530, whose light has traveled for 7.5 billion years to reach us.

The resulting data show us the quasar’s engine in incredible detail and will, astronomers say, help us understand the complex physics of these incredible objects, and how they generate such blazing light.

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It’s a hot new early dark energy summer.

We’re still not sure exactly what dark energy is, but it may have played a key role in the early universe.

Physicists can’t see or measure dark energy (hence the name). The only clue that it exists is how it affects the rest of the universe; dark energy is the force that’s driving the universe to keep expanding faster. Physicists Florian Niedermann of Stockholm University and Martin Sloth of the University of Southern Denmark propose that if dark energy formed bubbles in the dark plasma of the early universe, it could solve one of the biggest mysteries in modern physics.

They describe their idea in a recent paper in the journal Physics Letters B.

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These tiny black holes lose mass faster than their massive counterparts, emitting Hawking radiation until they finally evaporate.

One of the most intriguing predictions of Einstein’s general theory of relativity.

When a sufficiently massive star runs out of fuel, it explodes, and the remaining core collapses, leading to the formation of a stellar black hole (ranging from 3 to 100 solar masses).

Supermassive black holes also exist in the center of most galaxies.

So far, astronomers have captured images of two supermassive black holes: one in the center of the galaxy M87 and the most recent in our Milky Way (Sagittarius A*).

But it’s believed that another kind of black hole exists – the primordial or primitive black hole (PBHs). These have a different origin to other black holes, having formed in the early universe through the gravitational collapse of extremely dense regions.

Continue reading “Tiny black holes can compress Mount Everest into an atom size” | >

Wormholes are an intriguing bit that most people probably chalk up to science fiction. After all, seeing the Millennium Falcon barreling through hyperspeed in Star Wars is exciting, but there’s no way we could ever actually travel like that, right? Well, it might not actually be that impossible. According to new research, scientists were able to make a man-made wormhole using a quantum processor.

Of course, this isn’t to be misconstrued. They didn’t actually make a wormhole that someone was able to rip through space and time. Instead, they made a small, crummy wormhole on a quantum processor that could help teach us more about traversable wormhole dynamics. As such, the man-made wormhole, even if crummy, could be home to a plethora of data.

The physicists shared a paper detailing their findings on the man-made wormhole in the journal Nature. According to that paper, the “baby wormhole” was a successful attempt at observing traversable wormhole dynamics, something physicists have been trying to understand for decades. And, with scientists recently discovering a way to find wormholes in space, it could be more important than ever.

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Ali BeatrizAli Beatriz Ali BeatrizAli BeatrizPosted January 14, 2023 under Astronomy.

Astronomers have discovered a monstrous black hole with an appetite and a sweet tooth. The black hole is ripping apart an unfortunate star, stretching it like taffy and shaping the “leftovers” into a stellar donut the size of the solar system before feasting on this cosmic confectionary.

The All-Sky Automated Survey for Supernovae (ASAS-SN or “Assassin”) first spotted the violent incident, referred to as a tidal disruption event (TDE), via a flash of high-energy radiation. The feast is taking place at the heart of a galaxy 300 million light-years away.

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Black holes are bizarre things, even by the standards of astronomers. Their mass is so great, it bends space around them so tightly that nothing can escape, even light itself.

And yet, despite their famous blackness, some black holes are quite visible. The gas and stars these galactic vacuums devour are sucked into a glowing disc before their one-way trip into the hole, and these discs can shine more brightly than entire galaxies.

Stranger still, these black holes twinkle. The brightness of the glowing discs can fluctuate from day to day, and nobody is entirely sure why.

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How to make a black hole.
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There’s more than one way to make a black hole, says NASA’s Michelle Thaller. They’re not always formed from dead stars. For example, there are teeny tiny black holes all around us, the result of high-energy cosmic rays slamming into our atmosphere with enough force to cram matter together so densely that no light can escape.

CERN is trying to create artificial black holes right now, but don’t worry, it’s not dangerous. Scientists there are attempting to smash two particles together with such intensity that it creates a black hole that would live for just a millionth of a second.

Thaller uses a brilliant analogy involving a rubber sheet, a marble, and an elephant to explain why different black holes have varying densities. Watch and learn!

Bonus fact: If the Earth became a black hole, it would be crushed to the size of a ping-pong ball.

MICHELLE THALLER:

Continue reading “How to make a black hole | NASA’s Michelle Thaller | Big Think” | >

Results from a complex new analysis support cosmologists’ suspicions that something is missing from our understanding of the universe.

For the most part, our standard theory of cosmology fits observations like a glove. With just a handful of ingredients, scientists can explain the patchy pattern of the cosmic microwave background (CMB) — the relic radiation from the universe’s primordial age — and how the nearly uniform soup it came from transformed into the Swiss cheese of galaxy clusters and cosmic voids we see today.

But some nagging problems remain. The most touted is the Hubble tension, a discrepancy between how fast the universe appears to be expanding today and how fast it “should” be expanding, based on what we see in the early universe. But there’s another, more subtle discrepancy: Today’s universe is too smooth.

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