Aemilius wrote:It gives depth to buddhism, and is therefore essential to it.
It is not essential to Buddhism, any more than Meru Cosmology is.
If you don't accept it you will as an implication hold that transcedental vision is nonsense, that great teachers like Karmapa, Tsongkhapa, Nagarjuna and others are liars or worse, when they perceive the events of previous Yugas and previous Kalpas. I don't think you wish this either, do you ?
I think they uncritacally accepted the worldview handed down to them. I also think they had no tools to evaluate cosmological statements related to time and so on.
Sorry, when it comes to measuring the physical universe, we have a better understanding of it than ancient peoples.
In terms of eons, modern humans have only been out of Africa for 70,000 years or so.
The rest of it is religious speculation.
This of course does not mean that sentient life is confined to this planet, or that huge time frames mentioned in sutras are not relevant -- but there are issues with applying the fantastic numbers mentioned in sutras and so on to this planet and this crop of human beings.
On the other hand, it is fruitless to provide substitute speculations.
So we have to deal with two facts. Modern humans have only been present on the Indian subcontinent for at most 70,000 years. This fact stands in contradiction to traditional narratives about the history of Jambudvipa.
We should default to modern understanding, since it corresponds with the perception of ordinary people and is all that can be confirmed with any empirical certainty.
The beliefs of ancient Buddhist masters about the history of the world are pretty irrelevant.