[emhs]

The key difference is that we no longer posit that we know everything. We assumed we knew things we didn't, in ancient times, and in the process relied on hand-waves to keep moving, until some scientifically minded folks got too frustrated with the inconsistencies and started to accept that perhaps we didn't know it all. Now we know we don't know, and use the inconsistencies to tell how close we're getting to knowing enough to have consistent understanding.

The key is that we continue to improve our ability to gather evidence about what the universe looks like, and insist that our theories keep pace with the evidence we're gathering. So, the previous hand-waves occurred in large part due to insufficient data, and unwillingness to look for more. We've moved past that, to a large extent.