wrote:
That would be the total sum of all photons that have ever passed
beyond the event horizons of all black holes in the universe. That
might turn out to be quite a few photons.

I don't consider black holes to be outside of the universe.
In fact, massive black holes are the opposite of "absolute
nothing". They are so massive, they have collapsed the
structure of space, i.e. the ether.
--
73, Cecil http://www.w5dxp.com
"According to the general theory of relativity,
space without ether is unthinkable." Albert Einstein