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At Science Daily: Astronomers report most distant known galaxies, detected and confirmed


An international team of astronomers has discovered the earliest and most distant galaxies confirmed to date using data from the James Webb Space Telescope (JWST). The telescope captured light emitted by these galaxies more than 13.4 billion years ago, which means the galaxies date back to less than 400 million years after the Big Bang, when the universe was only 2% of its current age.

NASA: Webb’s image covers a patch of sky approximately the size of a grain of sand held at arm’s length by someone on the ground – and reveals thousands of galaxies in a tiny sliver of vast universe.

Initial observations from JWST yielded several candidate galaxies at extreme distances, as had earlier observations with the Hubble Space Telescope. Now, four of these targets have been confirmed by obtaining long spectroscopic observations, which not only provide secure measurements of their distances, but also allow astronomers to characterize the physical properties of the galaxies.

Astronomers measure the distance to a galaxy by determining its redshift. Due to the expansion of the universe, distant objects appear to be receding from us and their light is stretched to longer, redder wavelengths by the Doppler effect. Photometric techniques based on images captured through different filters can provide redshift estimates, but definitive measurements require spectroscopy, which separates the light from an object into its component wavelengths.

The new findings focus on four galaxies with redshifts higher than 10. Two galaxies initially observed by Hubble now have confirmed redshifts of 10.38 and 11.58. The two most distant galaxies, both detected in JWST images, have redshifts of 13.20 and 12.63, making them the most distant galaxies confirmed by spectroscopy to date. A redshift of 13.2 corresponds to about 13.5 billion years ago.

“These are well beyond what we could have imagined finding before JWST,” Robertson said. “At redshift 13, the universe is only about 325 million years old.”

According to Robertson, star formation in these early galaxies would have begun about 100 million years earlier than the age at which they were observed, pushing the formation of the earliest stars back to around 225 million years after the Big Bang.

“We are seeing evidence of star formation about as early as we could expect based on our models of galaxy formation,” he said.

Full article at Science Daily.

The JWST’s observations of the earliest galaxies are consistent with estimates of the finite age of the universe of about 13.8 billion years. A key point is that our universe had a beginning. Its finite age limits the probabilistic resources of the universe. It’s beginning from a spacetime singularity brings us to the question: “How can something come from [truly] nothing?”

Dick @4: A "year" is just a convenient, familiar unit of time for us humans. It means the same thing in cosmology as it does in measuring our own age. Caspian
I'm sure there's an easy answer to this, but I've not come across it: What does the term "year" mean in the context in which it's used to assess the age of the universe? What meaning does the term have apart from the earth's revolution around the sun, a measure that didn't exist until about 4.5 billion years ago? Is it based on "how long" it takes light to travel 6 trillion miles? Is there in cosmology something like an "absolute year," and if so, how is this squared with relativity? Dick
Seversky, your comment @1 is a nice summary of the Kalam cosmological argument for the existence of God. Barry Arrington
So we are looking at galaxies long ago and far, far away. It's a shame JWST doesn't have the resolution to spot any Death Stars. In reality, what's fascinating is that not only are we looking at the most distant galaxies, we are also looking at the distant history of our Universe laid out before us, a history that existed long before our solar system came into being in the path of that light. Seversky
I would say that something cannot come from truly nothing so, if our Universe has a beginning - and it seems that it does, then there must have been "something" that preceded that beginning. Seversky

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