What We Know of the Universe

I've recently watched a documentary called "Everything and Nothing" which is a two-part video on cosmology, exploring the history of astrophysics and quantum physics.

However great and fascinating I find all this, there is an aspect of science that bothers me: cognition.

It's easy today to look back at people of the past and find them silly because they thought the world is flat and contained in a shell. But without my education and conditioning, would I really know better now? How do I know the earth really is round? How much of what I think is science, in fact, mere belief from my part?

So it's a great thing to be open to what science is telling us, but is what it is telling us true? Has science limits? Science, based on observation can tell a lot, when observing the sky, if looking into the details, one can find out not all stars are on a single plane, and therefore, the world is not contained into a shell. For long too people thought our galaxy was the only one, until Hubble could demonstrate there were other galaxies like Andromeda, laying much more afar. Those who believed in the single-galaxy theory were proven wrong. But here it comes: space is expanding exponentially and in time, light from other galaxies will not be fast enough to reach ours, they will therefore be invisible to us. There would be literally no way to know there are other galaxies. Had humanity come to existence at this stage, humans would think there is merely one galaxy, the Milky Way, and all other knowledge of the Universe that exists today would be unknown. Science would be powerless at explaining the existence of the Universe. If such situations are possible then, how much more today can we not know? Can we know outside of space, outside of time? Can we speak of truly knowing the quantum world too?

So do I need scientific knowledge and all its equipment in order to know the Universe? How much can one rely on science? How much of this science is mere belief? How can I know, naturally, all what science tells me? Is what science provides really enlightening about existence and being? Does it make sense to rely on the reality we try to apprehend, in order to understand it? Can we for instance measure dreams with things of dreams? Can we measure what we call reality with things of reality? If our cognition is wrapped into the fabric of reality, can it really understand this reality objectively?