We don’t even understand the smallest phenomenon yet, nevermind the largest. When we apply our understanding and science on a quantum level, the matter we consist of matters less and less the smaller you go. Objects are no longer objects, solid is no longer solid, particles are no longer particles, atoms no longer atoms. We can’t even photograph things on this level because the mere action of taking a picture disturbs the view, particles of light smash through and rattle around, like someone throwing rocks into calm body of water and breaking a reflection, and so the mirror of what is visible is shattered. Space and time have no measurable effect at this scale. All we are left with is the vague strands of the relationships we take for granted and the useless bag of tools we brought with us to measure them - our half-formed perceptions of ‘reality’ and our irrelevant conceptualisations of the relationships between objects, our clumsy science, and blunt, unwieldy theories. The further down the rabbit hole you go, the more ill-equipped we are to understand the reality presented to us, and we struggle to grasp and document the new laws and principles that govern this strange, sizeless realm. We struggle to keep up, struggle to apply some kind of handle or alphabet or framework of understanding to what we learn. Quantum scientists are lost in an entirely new frontier, with no map or compass, driven by little more than faith and a sense of adventure, to what end even they do not know.
Who is to say we will not meet similar difficulties in measuring when we reach a larger scale? How do we know some other unmeasurable problems and puzzles wont arise at the edge of space? What if the void of space and time melts away to some other kind of void, some other incompatible dimensions to space and time itself, where matter isnt even welcome? What if everything we know and take for granted disintegrates? You’ve seen the artists renditions of the Ends of the Earth, where ships balance precariously at the edge of world as the ocean beneath them cascades down like a massive final waterfall into the void. This was a real theory once upon a time - the flat Earth theory. I think our knowledge of the cosmos that we have now is as undeveloped as the theory of the Earth we had back then. We thought there was a limit to the world before we knew it was a globe. We think there is a limit to the universe before we know it is something else. Will we ever reach the edge of everything and meet an impassable barrier, or will we pierce through the known into another unknown? Will our humble eyes be able to see it anyway once we get there? Is there an end? Was there ever a beginning? These are probably some of the biggest questions we'll ever ask.
I would say that physcists do have a good grasp of what's going on - even at the quantum level. The quantum world appears crazy and counterintuitive yes but we still have a good understanding of how things work. for example some of the very crazy and weird consequences of the quantum world were predicted beforehand and later were confirmed by experiment - so even though the quantum world appears completely counterintuitive to the logic we are used to, we are not ignorant of this and we do still have a good understanding of the way it works. In addition it's not that our measuring equipment is not good enough and even that that we are not smart enough to be able to measure things with certainty etc. - uncertainty simply appears to be an inbuilt feature of nature - we can not change this - all we can do is realise this, acknowledge it and use this information to build our knowledge about the quantum world and the way it works - this uncertainty and unpredictability is incorporated in the equations we use to mathematically describe the quantum world and those same equations have been used to shape the modern technological world.
Of course the nature of the theory itself means that things do not have definite outcomes but can only be discussed in terms of probabilities - but we have developed equations so that we can assign a probabltiy to a certain outcome. In this sense quantum theory is a hugely successful theory and it's predictions agree with experiment to a degree of precision that is unparalelled by any other theory of science. We have a good grasp of what's going on at the quantum level (although there are still debated issues such as the copenhagen interpretation/quantum measurement problem) - it's just that things due to the nature of the theory itself do not have definite outcomes or appear very wierd or crazy - but we can only say they are wierd or crazy by comparing to everyday logic (but practically speaking of course they are completely 'normal'). Physicsts have come to accept and fully embrace this quantum weirdness but the theory involves concepts so counterintuitve that we often hear physicsts say they do not fully understand the quantum world - indeed even the major pioneer of the theory said that if you are not shocked by it you have not fully understood it. So in summary what I would say is that although we accept that the quantum wrold is copletely counterintuitive and ruled by probabilities rather than ceratin outcomes we still have very good mathematical and scientific description of the way in which it works.
What we might ask is why does this wierdness exist, so for example how can a particle exist at two places at once or how can a particle 'communicate' instantaneously with its partner particle even though it were on the other side of the universe? But for practical purposes I don't see how that's any different form asking why does a law such as general relativity exist or even why does an electron exist or why do quarks exist or why does space or time themselves exist. A string theorist might say for example a string can vibrate in a certain way so that's why electron exists - but then where does that string of energy come from or where did the tiny dimesions of space that allow the string to vibrate a certain way come from? I think this is where the line between where science and philosophy becomes blurred.
Anyway sorry for going off on a tangent, lol.
Topic: The edge of space