The September 19, 2023 podcast with transcript Why the earliest galaxies are sparking drama and controversy among astronomers includes the following:
An article published earlier this year in the journal Monthly Notices of the Royal Astronomical Society came to this conclusion after combining two models of the universe. One is the commonly accepted model for the expansion of the universe. This model explains that as the universe expands, the light from galaxies must travel further and therefore shifts from a bluer to a redder spectrum of light. The other model it is combined with has been debunked. It's called the tired light model, and it alleges that as light travels across the universe, it gets redder because it gets "tired," or loses energy.
and addressing that is astronomer Jorge Moreno:
Moreno says that while he thinks that combining the models is clever, it is not supported by scientific evidence.
"I think in science, if you already have a model that's simpler than that, you should stick to it—unless you have extraordinary evidence to do otherwise."
Moreno also cautions people against quickly jumping on this supposition that the universe is twice as old as previously thought. If it were true, scientists would be able to prove it through the direct observation of stars and galaxies that are older than 13.8 billion years old—the current accepted age of the universe.
No such evidence has been found.
I'm not asking about Gupta's inclusion of "tired light", though I'm also not overly enthused about Moreno's advice that we should "stick to" simple models unless there is "extraordinary evidence to do otherwise" either.
Instead I'd like to better understand:
Question: What would evidence of stars and galaxies that are significantly older than 13.8 billion years old look like? In what part of space has such evidence been looked for and not found?