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SPACE: What Are Dark Sirens, And Why Should You Care?

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In recent years, cosmologists have been faced with a crisis: The universe is expanding, but no one can agree on how fast it’s moving away from us. That’s because different ways of measuring the Hubble constant, a fundamental parameter that describes this expansion, have produced conflicting results. But a single, lucky observation of what are known as dark sirens — black holes or neutron stars whose crashes can be picked up by gravitational wave detectors on Earth but remain invisible to ordinary telescopes — could help resolve this tension. As the cosmos expands, galaxies in the universe move away from … Read more

Earth’s 200 Million Year Growth Spurt

Earth's Core - Deposit Photos

Around 3 billion years ago, Earth’s crust ballooned during a massive growth spurt, geoscientists have found. At that time, just 1.5 billion years after Earth formed, the mantle — the layer of silicate rock between the crust and the outer core that was more active in the past — heated up, causing magma from that layer to ooze into fragments of older crust above it. Those fragments acted as “seeds” for the growth of modern-day continents. The researchers found evidence for this growth spurt hiding in ancient zircon crystals in stream sediments in Greenland. These extremely durable crystals — made … Read more

Is the Universe Expanding So Quickly Because of “Bumblebee Gravity”?

bumblebee gravity

Physicists have long assumed that the universe is pretty much the same in any direction, and now they’ve found a new way to test that hypothesis: by examining the shadow of a black hole. If that shadow is a wee bit smaller than existing physics theories predict, it could help prove a far-out notion called bumblebee gravity, which describes what would happen if the seemingly perfect symmetry of the universe isn’t so perfect after all. If scientists can find a black hole with such an undersized shadow, it would open the door to a brand-new understanding of gravity — and … Read more