The standard cosmological model (present-day version of “Big Bang,” called Lambda-CDM) gives an age of the universe close to 13.8 billion years and much younger when we explore the universe at high-redshift. The redshift of galaxies is produced by the expansion of the universe, which causes emitted wavelengths to lengthen and move toward the red end of the electromagnetic spectrum.

The further away a galaxy is, the more rapidly it is moving with respect to us, and so the greater is its redshift; and, given that the speed of light is finite, the more we travel to the past. Hence, measuring the age of very high redshift galaxies would be a way to test the cosmological model. Galaxies cannot be older than the age of the universe in which they are; it would be absurd, like a son older than his mother.

In work carried out with my colleague, Carlos M. Gutiérrez, at the Canary Islands Astrophysics Institute (IAC; Spain), we analyzed 31 galaxies with average redshift 7.3 (when the universe was 700 Myr old, according to the standard model) observed with the most powerful available telescope available: the James Webb Space Telescope (JWST).

Ripples in space-time from a pair of merging black holes have been recorded in unprecedented detail, enabling physicists to test predictions of general relativity

A new detection framework explains how astronomers can isolate extremely slow gravitational wave signals.

By combining subtle distortions in spacetime with observations of unusually bright galactic centers, the study authors have demonstrated a practical method for identifying likely locations of merging supermassive black holes.

The Big Bang is often described as the explosive birth of the Universe – a singular moment when space, time and matter sprang into existence.

But what if this was not the beginning at all? What if our Universe emerged from something else – something more familiar and radical at the same time?

In a new paper, published in Physical Review D, my colleagues and I propose a striking alternative. Our calculations suggest the Big Bang was not the start of everything, but rather the outcome of a gravitational crunch or collapse that formed a very massive black hole – followed by a bounce inside it.