Steinn Sigurðsson Astro 120 - 4

Note to self: Needs more links and images. More on anthropic next.

In the beginning, there was Ginnungagap - the great void - the cold of the north met with the fire of the south, and from it came eitur from which Ýmir the first of the giants was formed.
The race of giants sprung from his armpits, as he slept, as they do; and he fed from the great cosmic cow Auðhumla from whose udders flowed the four great rivers of the world.

Ýmir's sons killed him, and from his body the earth is formed, the stones from his bones and the sky is his skull, held up by the four cardinal dwarves (which spring from the maggots that ate Ýmir's flesh).
The first man, Búri, came from the ice when Auðhumla licked the salt stones (don't ask). He marries (who, you might ask) and Óðinn the All-father, all seeing and all wise, is his oldest son.
Rest follows.

There are nine separate worlds:

Miðgarður - our world
Ásgarður - home of the Gods, reached via Bifröst, the rainbow bridge.
Vanaheimar - home of the "other gods" (don't ask).
Jötunheimar - home of the surviving giants.
Álfheimar - home of the elves, natch.
Níð:avellir - home of the dwarves.
Niflheimar - the cold north.
Múspell - the fiery south.
and Hel, the underworld where the unglorious dead go to be forgotten.

The world will end Real Soon Now, after Fimbulvetur - when winter lasts three years and the wolves will eat the Sun and Moon. There will be an age of battle, and the earth will shake and the god of mischief, Loki, and the great wolf Fenrir, will be freed.

In the final battle everyone dies, except the fire giant Surtur, whose brand of fire will incinerate the world (middle world, world of the gods, maybe one or two others).

Some versions call for a rebirth and a new age, and then we do it all over again.

As a cosmology goes, this contains many of the essential concepts still bandied about in modern cosmology.
There is the notion of an (infinite and eternal) void; the world we are in arises spontaneously from a vacuum fluctutation that sets of a temperature gradient, followed by non-linear evolution to form structure and internal rearrangement to increase complexity, leading to organic chemistry, spontaneous quickening of life and evolution, diversification and reproduction.
The cosmology has a finite duration for the observable universe, with thermal death. There is an explicit notion of multiverses, and the destruction at Ragnarök has certain parallels with ekpyrotic universe models, with multiple planes of existence destroyed concurrently and thermally.
The concept of cyclic universes repeating broadly previous structure is also bandied about, albeit tentatively.
This primitive and inconsistent cosmology covers metaphorically a significant aspect of modern physical cosmology. That it does, should either cause us to worry about the cultural limitations of our cosmological models, or to marvel at our ability to stretch metaphors.

Contrast it with Hindu cosmology: "Then was not non-existence nor existence: there was no realm of air, no sky beyond it. What covered in, and where? and what gave shelter? Was water there, unfathomed depth of water? Death was not then, nor was there aught immortal: no sign was there, the day's and night's divider. That One Thing, breathless, breathed by its own nature: apart from it was nothing whatsoever. Darkness there was at first concealed in darkness this. All was indiscriminated chaos. All that existed then was void and form less: by the great power of Warmth was born that Unit...".

Here we have an explicit cycic universe within a larger chaotic universe - note the Hindu cosmology hints that time is not defined in this pre- or background state. The universe here last for a very long time compared to the lifetime of the observable universe and different cyclic states have different fates.
Again there are explicit metaphorical parallels with modern cosmology.

Alternatively, we are all children of the FSM - beware His Noodly Appendages, and look out for pirates!
All joking aside, pastafarianism provides an interesting contemporary view of myth creation and the development and expansion of consensual worldviews and creation models.

Principles

Modern cosmology, at least for the last four or five hundred years, can be considered a philosophical struggle between contending, overlapping cosmological principles.
In the scientific era, the contention is driven by observations of the actual observable universe. In particular whether it is infinite and eternal, vs finite or cyclical; and, whether the universe has a preferred center or viewpoint or not.

Ptolemaic Principle: this was the dominant viewpoint for almost two thousand years, driven by Aristotlean philosophy and adopted by the major monotheistic religions. In this worldview, the Earth is the natural center of the Universe and provides a privileged and special position.
The Ptolemaic Principle was overturned by the Copernican Principle, which demonstrated that observationally the local universe was not well described by an Earth-centric cosmology.
Initially the Sun was replaced as a preferred central point, but this was quickly dispensed with and the consensus is that there is no preferred center.
Cosmological Principle: the cosmological principle generalises the Copernican principle, and asserts that the universe is homogenous and isotropic. That is, it is similar wherever you go and looks much the same in any direction.
Locally the cosmological princple fails, the universe is heterogenous and highly anisotropic on small scales; but observationally it looks valid on large enough scales. The relevant scale is roughly 300 million light years or larger.
Perfect Cosmological Principle: the perfect cosmological principle asserts that the universe is homogenous in time. That is, that things stay much the same on average through the ages.
Observationally, the perfect cosmological principle is false, the universe evolves strongly with time and its current state is very different from its earlier states.
One might worry, in principle, that if one were to average over very long time scales (much larger than 10 billion years, which is the time scale we have data for) that then the universe is, on average in fact homogenous. This is conceivable but there is no evidence to support it and not clear if we could ever tell.
Principle of Mediocrity: the principle of mediocrity asserts that we ought to be an average lifeform on an average planet orbiting an average star in an average galaxy at about an average time in the universe.
This may well be true. We know the Sun is fairly average and the Milky Way is a pretty average galaxy. We suspect the Earth may be a fairly average planet - even if it is unique within the Milky Way, which is possible, then there would still be about a trillion Earth like planets within the observable universe distributed in different galaxies.
We still don't know how average we are. Our specialness, or lack thereof, is completely contaminated by our observer bias.

In counter to these great principles, is the Anthropic Principle...

Last updated 01/13

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