If You Could See Gravitational Waves, the Universe Would Look Like This

A simulation of the sky seen in gravitational waves. Credit: NASA’s Goddard Space Flight Center

Imagine if you could see gravitational waves.

Of course, humans are too small to sense all but the strongest gravitational waves, so imagine you were a great creature of deep space, with tendrils that could extend a million kilometers. As gravitational waves rippled across your vast body, you would sense them squeezing and tugging ever so slightly upon you. And your brilliant mind could use these sensations to create an image in your mind. The ripples of distant supernovae, merging black holes, the undercurrent of the gravitational background. Creation, and destruction, all seen in your mind’s eye.

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We Can't See the First Stars Yet, but We Can See Their Direct Descendants

This artist’s impression shows a Population III star that is 300 times more massive than our Sun exploding as a pair-instability supernova. Credit: NOIRLab/NSF/AURA/J. da Silva/Spaceengine

If you take a Universe worth of hydrogen and helium, and let it stew for about 13 billion years, you get us. We are the descendants of the primeval elements. We are the cast-off dust of the first stars, and many generations of stars after that. So our search for the first stars of the cosmos is a search for our own history. While we haven’t captured the light of those first stars, some of their direct children may be in our own galaxy.

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Dark Photons Could Be the Key to Both Dark Matter and the Muon Anomaly.

An artistic view of light becoming matter. Credit: Gerd Altmann, via Pixabay

If dark matter exists, then where are the particles?

This single question threatens to topple the standard cosmological model, known as the LCDM model. The CDM stands for cold dark matter, and according to the model makes up nearly 85% of matter in the universe. It should be everywhere, and all around us, and yet every single search for dark matter particles has come up empty. If dark matter particles are real, we know what they are not. We don’t know what they are.

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First Contact Could Turn Out Well for Humanity

Illustration of a radio telescope listening for signals from an alien civilization. Credit: Zayna Sheikh, Breakthrough Listen

You’ve heard this story before. An advanced alien race comes to Earth. They offer peace and prosperity, but they hold a dark secret. One that could destroy humanity. That dark secret has varied over the years, from stealing our water, books on culinary advice, or communism, but the result is always the same. First contact with advanced extraterrestrials goes very badly for us. But in reality, how bad could it be? That’s the question a new study examines using game theory and Hobbesian philosophy.

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Polar Ring Galaxies Are Bizarre and Rare. Astronomers Just Found Two More

A galaxy with a polar ring of hydrogen gas, known as a polar ring galaxy. Credit: Jayanne English, Nathan Deg & WALLABY Survey, CSIRO/ASKAP, NAOJ/Subaru Telescope

Galaxies come in a range of shapes, from elegant spirals to egg-shaped ellipticals. We often categorize galaxies by their shape, which was traditionally done based on what we could observe in the visual spectrum. But as we expanded astronomy into radio, infrared, ultraviolet, and x-ray light, learned that often galaxies have structures invisible to our eyes. Take, for example, an odd type of galaxy known as polar ring galaxies (PRGs).

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An Ambitious New Technology Might be Needed to See Other Earths

How a starshade would reveal exoplanets. Credit: NASA/JPL

The race is on to discover truly habitable Earth-like worlds. While we are starting to observe the atmospheres of large potentially habitable planets such as Hycean worlds with the telescopes we currently have, the most significant breakthroughs will likely come with the development of advanced specialized telescopes. These new designs will likely use a starshade to hide the glare of a star and allow us to directly observe its exoplanets. But will that be enough to study distant terrestrial planets?

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The Milky Way's Disk is Warped. Is That Because our Dark Matter Halo is Tilted?

Illustration of the Milky Way's warped shape. Credit: ESA/Stefan Payne-Wardenaar

It’s difficult to determine the shape of our galaxy. So difficult that only in the last century did we learn that the Milky Way is just one galaxy among billions. So it’s not surprising that despite all our modern telescopes and spacecraft we are still mapping the shape of our galaxy. And one of the more interesting discoveries is that the Milky Way is warped. One explanation for this is that our galaxy has undergone collisions, but a new study argues that it’s caused by dark matter.

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A New Observatory Will Spot Core-Collapse Supernovae Before They Explode

Jiangmen Underground Neutrino Observatory (JUNO) under construction. Credit: CGTN

The thing about a supernova is that you never know when it might occur. Supernovae are triggered either by a collision with another star or when the interior of a massive star becomes depleted of nuclear fuel and begins a rapid collapse. Neither of these show any major optical changes before the explosion, so we are left to scan the sky in the hopes of catching one in its early stages. But that could soon change.

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A 2022 Gamma Ray Burst Was So Powerful, it was Detected by Spacecraft Across the Solar System

Artist's depiction of a powerful gamma ray burst. Credit: NASA, ESA and M. Kornmesser

On October 9, 2022, a gamma-ray burst illuminated the solar system. Its light had traveled 2.4 billion years to reach us, having begun its journey when only bacteria and archaea existed on the Earth and oxygen was not yet plentiful in our air. Despite its long journey, the flash of light was tremendously bright.

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If Neutron Stars Have Mountains, They Should Generate Gravitational Waves

Artist's depiction of a highly magnetize neutron star known as a magnetar. Credit: NASA's Goddard Space Flight Center/S. Wiessinger

A neutron star is 2 solar masses compressed into a ball only 12 kilometers wide. Its surface gravity is so immense it compresses atoms and molecules into raw nuclei and squeezes electrons into protons transforming them into neutrons. Given such immense pressures and densities, you might assume neutron stars have an almost perfectly smooth surface. But you’d be wrong because we know that neutron stars can have mountains.

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