Tag: Ethan Siegel

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Cosmology’s biggest conundrum is official, and no one knows how the Universe has expanded

Cosmology’s biggest conundrum is official, and no one knows how the Universe has expanded

After more than two decades of precision measurements, we’ve now reached the “gold standard” for how the pieces don’t fit.

This is a direct copy of a SciPop or news article preserved here because things on the internet have a bad habit of disappearing when you try to find them again. Full credit is given to the original authors and the source.

– Matty
  • There are two fundamentally different ways of measuring the expanding Universe: a “distance ladder” and an “early relic” method.
  • The early relic method prefers an expansion rate of ~67 km/s/Mpc, while the distance ladder prefers a value of ~73 km/s/Mpc — a discrepancy of 9%.
  • Owing to Herculean efforts by the distance ladder teams, their uncertainties are now so low that there is a 5-sigma discrepancy between the values. If the discrepancy isn’t due to an error, there may be a new discovery.
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