Tom Metcalfe

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    A Cosmic Glitch in Gravity

    Is gravity weaker over distances of billions of light-years?

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    Nine Rebel Astronomy Theories That Went Dark

    Bright ideas from astronomy’s biggest stars haven’t always worked out.

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    Could Modified Gravity Kill Planet Nine?

    A controversial theory can explain phenomena attributed to the mystery planet.

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    How Did Life Begin?

    By imitating early conditions of Earth in the lab, scientists gain new insight into the origin of life.