Kitsune, that's a fair enough post. I never said that an Oort Cloud wouldn't be discovered someday, or something resembling one, but until now, one has not been observed, only hypothesized.
Also, remember that the reason that the Oort cloud and Kuiper belt were hypothesized is that we know that new inner-solar-system comets are coming from
somewhere.
An astronomer explains:
Because of their high mortality rates, periodic comets cannot have been periodic for long but must originally have been comets of very long periods having nearly parabolic orbits. Within the recent past (perhaps the last few thousand years) their orbits have been drastically altered to their present relatively small size by perturbations produced by the planets, especially Jupiter. Those occasional comets that are highly spectacular, and hence cannot have suffered appreciable disintegration, almost invariably have nearly parabolic orbits, and also they have not been seen before in recorded history. --- George Abell, Exploring the Universe
New comets turn up. The hypotheses of Oort and Kuiper try to explain
where they come from, but the creationist argument is shot down by the fact that they
do.
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This was one of the first YEC arguments I came across. Short orbit comets, I was told, can only go fifty times round the Sun before evaporating completely.
So I googled to find out the comet with the
shortest known orbit. It's Enke's Comet, and it has a period of 3.3 years. If comets only get fifty trips round the Sun, and if you can use them to date the solar system ... then the solar system was created in 1845, tops.
The alternative explanation is that it only recently became a short-orbit comet, and used to be further out. Unless you believe that the solar system was created eighteen-and-a-half centuries after Christ, you have to believe that explanation.
So whether it came from the Oort cloud, from the Kuiper belt, from the depths of galactic space, or from giant space aliens having a snowball fight, is immaterial to the question of whether you can use such comets to date the solar system. Clearly, you can't.