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Astronomy

Cosmological Constraints on the Hubble Constant from Time-Delay Lensing of Quasars

Quick fact

Time-delay lensing measurements of quasars provide a one-step geometric measurement of the Hubble constant, free from the distance ladder's step-by-step calibration, and have measured H0 around 70-75 km/s/Mpc, contributing to the 'Hubble tension'.

Why this is interesting

Imagine seeing the same quasar at four different points in the sky, each flashing at a slightly different time. This cosmic mirage can reveal how fast the universe is expanding—but how?

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Cosmological Constraints on the Hubble Constant from Time-Delay Lensing of Quasars

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