That “we won’t see it in our lifetime” line is absolutely ignorant, could happen any second.
Exactly so. I knew someone (now deceased, some years ago now) who had a so-called genius level IQ (north of 150) who saw a magazine open on my desk (uh, I was reading that during my break) with an article about Chicxulub or something. He said that's impossible, those things burn up in the atmosphere. :^)
About 20 years ago (and this was before the number of known Near-Earths was anything like it is today) the odds of dying in an impact (given the number of known large impacts, which has also risen, over the lifetime of the Earth), were shown to be worse than the risk of dying in a plane crash. In part that's a tribute to how safe air travel is, of course, but *most* people don't expect to die in a plane crash, and by and large we are correct about that.
My view is that the mass extinction impacts and basically all or nearly all large impacts have been by NEOs, because those encounter the Earth (usually at great distances) on very regularly and routinely, and there are a lot of them (fewer than there used to be, due to kabooms into the Earth), and a lot of encounters for each one.
I've never had much use for the Nemesis model, wherein there's a currently undiscovered outer solar system body that disturbs the Oort Cloud every x millions of years, leading to a period of near misses and one big bombardment. That's just a uniformitarian's way of tryint to feel good about random catastrophes.
Absolutely. We tend to view our movement through the universe in a 2d frame of mind when in reality it is 3d. Not only are we orbiting the sun in our solar system, the solar system is corkscrewing us through stuff in rotation path as our arm of the galaxy circles the galactic center. And I would speculate that besides expanding, all the galaxies are also rotating around the center of the universe just like a galactic center.
All this compounds and greatly raises the probability and chances of running into something we can’t figure on. It’s like saying we have distances in the far north and the far south all figured out by using a Mercator projection map. They are not at all accurate compared to 3d globe distances and real distances. When figuring the movement of our earth we are only figuring in X and Y axis when in reality there are six or more.
And I am a firm believer that there are more than one physical universes, I think they could be just as numerous as the galaxies which adds another influence of movement. We just don’t see them yet and we will refuse to accept this possibility until we physically see it. It’s an antiquated flaw in our logical and reasoning skills that hinders discovery and reality.