On our 3D universe, there are different "universes" or levels of existence, with different time
scales, and different sizes and dimensions.
There is the "universe" of the animal size organisms, then there is the
insect level, which are from 100 to 1000 times smaller than us, then there
is the bacteria/fungi level, then the organelle level, then the atomic level,
then the subatomic particle level. There is the planetary level, stellar level,
galactic level, galactic cluster level, and universe level.
There is also the black matter universe that exists in our same universe, everywhere you go,
everywhere there is mass there is dark matter. It's like a universe within a universe.
If we all were the size of a bacteria, and even if we were bacteria, we would not have
neither the body functions nor the intelligence nor any of the tools required to comprehend that
we are indeed just so tiny to be able to graps our entire universe.
We could say we live in a simulation at this scale, but in reality we are just very down the dimensional scale of our universe.
What if our entire universe is just part of something much more bigger, and that in itself, it's a tiny
part of something much more bigger, but we don't have the tools nor the senses to acknowledge that.
Please check this video because it's what I'm about to explain next:
https://www.youtube.com/watch?v=Mk4TkVNGwvk
Now, if you see Carl Sagan's explanation of the 2D citizens, they are not able to comprehend that they are in a 3D world
in reality, and that apple it's just the projection of a 3D object.
In our case, we are 3D citizens, living in an apparently 4D universe. Since we live in a 3D world, we don't have the tools
nor senses, nor anything required to detect, comprehend, or visualize that we are indeed in a 4D world. We can use indirect
methods, like using a clock and measuring with a ruler, but that itself does not allows us to comprehend 100% a 4D universe.
Can you point the direction where the time is flowing? You could say foreward, yes, but, in what spatial direction?
We can't point anywhere because time it's ortogonal to all 3D coordinates.
If you were a 4D being, you could easily visualize the 3D universe from a higher and priviledged perspective, and could move back
and forth in time and space instantly without a problem.
Now, ignoring string theory, I really think that our 4D universe is just a projection of higher dimension universes.
Those who are in a 5D dimension, could literally move things arround without any of us noticing or without making any sense.
For us, those 5D beings could be called gods, but those in turn could be part of a 6D universe, and so on.
Our entire 3D universe could be just a tiny spot on a 4D universe. And that entire 4D universe, could be just a tiny spot in a 5D universe,
and so on with the higher dimensions. It could be impossible for our 3D minds and tools to even remotely
wonder how the 9nth dimension would look like.
We could say that we live in a simulation, but I think that more than that, that our entire universe is just a tiny spot of some
higher dimension. Perhaps some 5D kid playing arround making 4D universes.
For a 5D being the entire life of our 3D/4D universe could be a blink of an eye.
Every dot in a 5D universe could be what we call a parallel universe.
I think that the only way to explore higher dimensions is through spirituallity, and why not, science. But science's tools
are so limited in a sense that they always stick to their 3D mindset, and if something is not 3D then it must not be real.