I make no assumptions about how highly "the odds are stacked" against them having been alien ships, Steve. Others may make such assumptions, but I don't. It's possible that they were secret vehicles being flown around by the US government, and I've considered that possibility, but have no way of investigating it further. It seems to be the only other one with much likelihood. In any case, I figure they were either one (alien ships) or the other (secret government vehicles). I make no assumptions about where they might have come from if they were alien ships...nor do I assume that our present scientific knowledge of the laws of physics and the possibilities of space travel, etc, is complete. It's never been complete in any previous century...why would it be complete now? ;-) I make no assumptions that faster-than-light travel is impossible either. Why would I? Because a presently accepted and popular scientific theory says so? Ha! As if we already knew it all....!

What we know, Steve, is what we have encountered directly and proven through our own firsthand experience. The rest is theory and speculation or is just plain below or above our radar (meaning we haven't even thought about it yet). What we know is a fingernail shaving, in other words.