Message #225388

[Guyfolan]

9. BEYOND THE OBSERVABLE UNIVERSE The expansion of the universe is defined by a parameter called Hubble's constant, which relates the distance of a far galaxy with its velocity of recession. Beyond a certain distance the recession velocity exceeds the speed of light. Objects beyond this are red-shifted to infinity and are unobservable. This distances defines the edge of our observable universe, an event horizon, and lies approximately (subject to experimental error) 15-30 billion light years away. This is limit of the astronomer's universe. What lies beyond is pure conjecture and is left to cosmologists. Cosmological theories expounded over the last decade (in particular inflationary theories) indicate that the observable universe is just an infinitesimal speck in a greater post- inflationary bubble that extends over distances of 10^30 light years or more, looking pretty much everywhere as it does here. Inflationary theories differ about what lies beyond this, although one suggestion is that naturally occurring wormholes, inflated to astronomical dimensions, [6] may link our post-inflationary, bubble with others, forming an infinitely large chaotic, fractal structure [17]. Unless we link up with aliens then we may never directly observe this since these regions will have changed greatly in the century or two of empire-time (> 10^30 years of co-moving time) it takes to reach them.

A couple of paragraphs back I mentioned the phase change, Link-Up, associated with linking up with the rest of the universe. It's worth while stopping for a moment and considering what this might do to our perception of ourselves and our place in the universe. At the moment we are the only civilisation we know, unique and conceited. Even if civilisations are scattered at distances of 100 million light years, in a universe of radius 10^30 light years this still yields over 10^60 alien cultures. It is unlikely anyone could ever catalogue all the civilisations and cultures, even if they did have a nanoelectronic brain! No single mind could encompass all of history. We would have returned to the medieval world, surrounded by legends of distant lands populated by mythical and fantastic creatures. Construction of a universal map would be impossible. A trans-human traveller, exploring the highways and byways of life, would likely never encounter another trans-human, beyond the 'here be dragons' point. If she lost her personal wormhole and forgot her trans-species designation code (a sixty digit number!) she would never, ever find her way home again. None of her descriptions of where she comes from would relate to anything anyone else knows.