Free Astronomy Magazine January-February 2024

JANUARY-FEBRUARY 2024 13.8 billion years ago, an age that appears too recent to justify the morphology and stellar content of the galaxies born in the first billion years. For those galaxies to have de- veloped so rapidly, it would be nec- essary for all the gas in the universe to have transformed into stars with an efficiency close to 100%, which is a scenario that does not seem re- alistic. For a few years now, astronomers have been trying to find a reason- able solution to the problem of pre- cocious galaxies. Of all the proposed solutions, the most surprising one states that the universe could have been born not 13.8 billion years ago, but 26.7 billion years ago! This disconcerting hypothesis was pro- posed last summer by Rajendra Gupta (Faculty of Science at the Uni- versity of Ottawa) in an article pub- lished in the Monthly Notices of the Royal Astronomical Society . Initially, the article did not have a great re- sponse, but with the multiplication of discoveries of precocious primor- dial galaxies, it has begun to arouse more and more interest. To better understand Gupta’s claims, we must go back to 1929, when Fritz Zwicky (famous for having pro- posed the existence of dark matter, as well as the origin of gravitational lenses and neutron stars) formu- lated the concept of “tired light” to explain the redshift-distance of galaxies relationship within a sta- tionary universe. Zwicky’s model was intended to be an alternative to that of the expanding universe, pro- posed shortly before by Georges A mosaic created with images from the James Webb Space Telescope of a re- gion close to the Big Dipper, with inserts showing the position of six new galaxies existing between 500 and 800 million years after the Big Bang. These galaxies have a similar number of stars to the Milky Way, but are packed into a much smaller space. [NASA, ESA, CSA, I. Labbe (Swinburne University of Technol- ogy). Image processing: G. Brammer (Niels Bohr Institute’s Cosmic Dawn Center, University of Copenhagen)] M ulti-wavelength observations of ceers-2112, a barred spiral galaxy with redshift z=3, which was already surprisingly mature when the universe was only two billion years old. [Nature, L. Costantin et al.]