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Accelerating Expansion Reveals Dark Energy Amid Century-Long Cosmic Milestones

7/4/2026

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Summary

Story summary

In 1998 Saul Perlmutter, Adam Riess and Robert Kirshner announced accelerating cosmic expansion, introducing dark energy.
In 1929 Hubble’s redshift data showed galaxies recede, confirming expansion.
In 1923 Hubble photographed Andromeda, proving it is a separate galaxy.
In 1887 Albert A. Michelson and Edward W. Morley disproved the ether.
In 1920 Arthur Eddington proposed hydrogen-helium fusion powers stars, later detailed by Hans Bethe.

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Story summary

In 1998 Saul Perlmutter, Adam Riess and Robert Kirshner announced accelerating cosmic expansion, introducing dark energy.
In 1929 Hubble’s redshift data showed galaxies recede, confirming expansion.
In 1923 Hubble photographed Andromeda, proving it is a separate galaxy.
In 1887 Albert A. Michelson and Edward W. Morley disproved the ether.
In 1920 Arthur Eddington proposed hydrogen-helium fusion powers stars, later detailed by Hans Bethe.