Multiple lensed images of supernovae help pin down the Hubble constant:
“If SN Requiem reappears this year, it will lead to a higher value of the Hubble constant and validate the astronomers’ camp. If the supernova is not seen until next year, it will lead to a lower value…”
It’s astonishing that we can (sometimes) see the same supernova *billions* of light years away along multiple gravitationally-lensed paths that produce time differences on the human scale of 10 years or so.
https://www.science.org/content/article/how-fast-universe-expanding-cosmic-illusions-may-hold-answer
This is a great article — worth savouring not skimming — packed with human and scientific drama as it delves into the history of this idea going back to a 1964 thesis by Sjur Refsdal. Fifty years later, the first supernova used in this way was named SN Refsdal.
Greg Egan
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2026-04-09 03:18:36 UTC
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2026-04-09 03:18:36 UTCEvent JSON
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