What proof could Ragnarök leave behind?

Question

Ragnarök is the Norse rendition of the apocalypse. A major event during this apocalypse is Fernir devouring the sun. If we assume that the sun and all of its influence disappear entirely for 3 days, this could have serious effects on the environment.

Another side effect of Ragnarök for the purpose of this question is that humanity and all traces of them are wiped out, with the exception of two humans who then repopulate the earth.

Assuming that gods meddle in human affairs from time to time and the possibility of Rangnarök is known to be real (this means that the gods, including Fernir, have been proven to exist), how could humans with knowledge of science similar to ours prove with statistical significance Rangnarök already occurred once a few ten thousand years ago? This should take into account all effects that the absense of the sun would have.

Additionally, could it be shown that these traces were not the result of an original creation?

We know however that we won't be able to do this using astronomy.

Answer 1

Genetic evidence

We know that the Mitochondrial Eve (the closest common female ancestor of all living humans) lived 100,000 to 200,000 years ago and the Y-chromosomal Adam (closest common male ancestor of all living humans) 150,000 to 300,000 years ago. They likely never met. How is that possible? Doesn't matter for this question, but what does matter is that the scientific methods which were used to find this out could also be applied in your world to find out that both only lived 10,000 years ago.

There would also be a very small genetic diversity among humans when all would descend just from the genome of two people and that genome only had 10,000 years to get any new information through mutation.

By the way: According to this source, a single human couple might not be enough to repopulate the earth. A gene pool of at least a few dozen, better a few hundred, individuals is required for a stable population, otherwise the species will inevitably die out after a few generations (the big plothole in oh so many creation myths). But I don't want to kill your whole premise, so let's ignore this problem for now.

Cultural evidence

When the whole world population was reduced to two people, their descendants would likely be concentrated in a very small geographical region for several generations. Only when that area would start to suffer from overpopulation would they start to colonize areas further away. Humans would spread geographically, but this would be a very slow process. That would result in the oldest cultures all emerging in one region and subsequently younger cultures emerging further away.

It would be obvious that human culture emerged from just one point and then spread slowly over the whole planet.

Archeological evidence

When Ragnarök also destroyed all archeological evidence of existing civilizations, it would be notable that no remains of human civilization older than 10,000 years exist. When Ragnarök left ruins behind, it would be notable that all civilizations ceased to exist at exactly the same time, and that it then took several millennias until new civilizations emerged in the same area and that those had no cultural connections to those which were there before.

Fossil evidence

You said that animals and plant-life also suffered from Ragnarök and its aftermath. This would likely mean a mass-extinction event which caused several unrelated species to suddenly become extinct. We know that several such events happened in the history of Earth due to fossil evidence, and for most of these events there are theories (of varying acceptance) why exactly they happened.

Geological evidence

A very interesting evidence for how climate has evolved on our planet is through ice core sampling from polar ice or glaciers. Every year a new layer of polar ice forms, and by looking at each layer we can tell how the climate was in that year. By analyzing particles contained in the ice we can also find atmospheric contaminations.

It is possible to retrieve core samples from hundreds of meters below the surface which provide us with information about the climate over 100,000 years ago.

The Ragnarök event would likely result in the ice layer for that year to be quite unusual.

Bottom-line

It might not be obvious what exactly happened, but it would definitely be impossible to deny that some cataclysmic event happened exactly 10,000 years ago and that this event drastically decimated the human population to very few individuals at one location.

You said in a comment that "they disappear without a trace, along with all direct proof of them ever being there". When this premise is absolute, there is by definition no way to tell the difference between survivors and humans which were newly created at that moment.

Answer 2

I'll just add a couple of other things to Philipp's answer which would be noticeable after thousands of years, even if all trace of humans is scoured from the globe. Of course, this depends on how far the "scouring" actually goes -- if the scouring process also includes undoing the effect humans have had on nature, then of course it's going to be harder to detect (up to impossible, for a complete reversion to a pre-human state).

Missing resources

All of the resources we've extracted might stay gone. That's mammoth amounts of iron, copper, gold, silver; probably most of the easy-to-exploit deposits of all of these are largely gone. There's an awful lot of coal left, but most of the easy deposits of oil are gone too. A future geologically sophisticated civilization would be able to see that, theoretically, there should be a lot more of all of these resources, and more to the point, they should be in much easier to find deposits.

Holes

Like, actual physical holes. Open-pit mines are enormous, and even after thousands of years enough regular mineshafts would still be around to create questions. And modern cities are artificial a long way down: hundreds of feet in some cases. Completely removing them would result in pits hundreds of feet deep and miles across. Most cities are on rivers or the coast, so these would be a lot easier to silt in, but geological surveys would reveal that there had been big holes there.

Biological changes

Humans have made significant changes to lots of different species. Domesticated plants and animals are found all over the world, despite originally coming from geographically constrained places. It would be a puzzle to biologists to explain why virtually identical species of, say, sweet potatoes and bananas are found throughout the tropics, despite their closest relatives being only found in South America and New Guinea, respectively. The same is true for cows, horses, pigs, rice, maize, beans, potatoes, coffee, and a hundred other species.

To say nothing of how Norwegian rats are found on every island larger than a few square kilometers.

Answer 3

There is - believe it or not - a loophole that could show give solid evidence that Ragnarok happened. It involves a black hole (or a very massive body).

One of the coolest effects of general relativity is that mass and energy can bend light. It's known as gravitational lensing, and it often is shown as this:

You can bend the light to any angle. So all you have to do is put a massive object somewhere in the cosmos. Position it so that the light from the Sun reflected off of Earth will bend around it and come straight to Earth (this is nearly impossible because of the motion of the Earth, but hey, perhaps there's a solution). If this was done in the past, we could "look back in time" and see the solar system in the past. If we found a severe irregularity, such as the complete lack of an image of Earth - or an actual image of Ragnarok - we could tell that something had happened.

Answer 4

Much easier to disprove then to prove as mass extinction can not be hidden. lets take the other aspect; "If we assume that the sun and all of its influence disappear entirely for 3 days...". The absence of gravity, being one of those influences, would cause the Earth to leave its orbit, and the reappearence of the Sun three days later would not correct the problem, so we could not be here now to debate the matter. Ergo, it didn't happen that way. You could say that some God pushed the Earth back into its orbit but then you are relying on mystical interference without a physical basis, which would screw up any attempt to come up with scientific explanations for the universe, preventing the formation of a scientifically competent society in the first place. In science - any proof that a theory is wrong means that the theory is wrong.

If you want to change your starting point to "If we assume that the sun and some of its influence disappear entirely for 3 days..." then you need to specify which influence dissappered. Remove light or heat etc. and it would show in the growth record, though you would need very advanced science to find it. Combine it with a mass-extinction event and the evidence would be obvious. The same applies to any other influence you can identify.

Any society that develops a knowledge of science similar to ours must eventually chose between living in a natural world understandable by science and a super natural world requireing gods to explain.