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are you talking abut the Methusala star? Because their is plenty of reasons those age projections could be off / skewed.
Not specifically. We see galaxies that are 40 billion light years away when they couldn’t have existed 15 billion years ago. Einstein’s theory of general relativity was working perfectly fine until we made that realization, then all of a sudden there’s a dark energy that expands space faster than the speed of light. We can’t measure it or observe it but we just accept that it must exist because it’s the only way our current model can exist, rather that questioning whether the current model is accurate at all
stupid layman question..... how can we know that specific light is 40 billion years old?
I think the distance is easier to measure than the time, but they’re both correlated. It takes light a year to travel one lightyear, so a galaxy that’s 40B lightyears away should require 40B years for that light to reach us, while we operate within a model that says the universe began only 14B years ago (not possible for light to travel 40B light years in 14B years).
I guess I still don’t have an immediate answer to your question, I know that red- and blue-shifting of light helps us tell how fast a galaxy is moving away from or toward us, respectively, but I assume they’re able to compare one galaxy to another and gauge the distance away that one must be versus the other, allowing us to “ladder” the distances from one galaxy to the next. At a minimum, anyway.
Regardless, they confidently tell us that they imaged a galaxy 100 billion light years away, and that that can only happen within a 14 billion year timespan because space has expanded and moved that galaxy away from us faster than the speed of light, though that isn’t directly accounted for in Einstein’s theory of general relativity. It’s just an adjustment we’ve made because without the adjustment, the theory would have to be wrong
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