Dark Energy That Will Disappear
Since the late 20th century, astronomers have known that the recession of galaxies is accelerating, as if pushed by an invisible tailwind.
Fossil Clocks: How Relic Galaxies Measure the Expansion of the Universe
In the heart of an old city stands a clock tower whose hands have never been adjusted since it was built. By how far it runs slow, you can calculate how much time has stretched since then. In space, the role of such towers is played by relic galaxies — dense stellar systems that formed in the first few billion years and have since neither merged with neighbors nor given birth to new stars.