The Observable Universe
Illustration Credit &
Licence:
Wikipedia,
Pablo Carlos Budassi
Explanation:
How far can you see?
Everything you can see, and everything you could possibly see, right
now, assuming your eyes could detect all types of radiations around you
-- is the
observable universe.
In visible light, the farthest we can see comes from the
cosmic microwave background, a time
13.8 billion years ago
when the universe was opaque like thick fog.
Some neutrinos and
gravitational waves
that surround us come from even farther out, but humanity does not yet have the technology to detect them.
The featured image illustrates the observable universe on an
increasingly compact scale, with the
Earth and
Sun
at the center surrounded by
our Solar System,
nearby stars,
nearby galaxies,
distant galaxies,
filaments of early matter, and the
cosmic microwave background.
Cosmologists typically assume that our observable
universe is just the nearby part of a greater entity known as "the universe" where the same physics applies.
However, there are several lines of popular but speculative reasoning that
assert that even our universe is part of a
greater multiverse where either different physical constants occur,
different physical laws apply,
higher dimensions operate, or slightly
different-by-chance versions
of our standard universe exist.
Source: NASA