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A comment on If the universe is 13.8B years old, how can we see 46B light years away? (2018). Parent comment

Re:If the universe is 13.8B years old, how can we see 46B li... by nuccy on Saturday December 07, 2019 @03:15PM (#21732316)
It is also peculiar that the energy conservation law is not applicable on cosmological scales, the light is redshifted due to expansion of the Universe and the energy difference between emitted and received light is "wasted", i.e. it doesn't feed the expansion in any way.
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Re:If the universe is 13.8B years old, how can we see 46B li... by cygx on Saturday December 07, 2019 @03:28PM (#21732366)
I don't know if 'feeding expansion' is necessarily the right way to think about this, but by the first Friedmann equation, loss of photon energy will in fact be balanced by the increased expansion rate...
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Re:If the universe is 13.8B years old, how can we see 46B li... by nuccy on Saturday December 07, 2019 @03:43PM (#21732428)
Sure, though the first Friedmann equation, or any other equation, where terms are balanced, e.g. a + b = 0, doesn't tell you anything about causality, though redshifting of light is exactly caused by expansion, so it is not strange that both are "balanced".
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