.. _apftu:

=================================
 A New Paradigm for the Universe
=================================

I had just read Fred Hoyle's, :ref:`notu`, when I discovered Colin
Rourke's work on cosmology.

It was 2017 when `A new paradigm for the universe
<https://arxiv.org/abs/astro-ph/0311033>`__ was published.  A
second edition under the title, :ref:`gotu` was published in 2021.

I came to the ideas as someone with a keen interest in cosmology, but
an open mind to the details.

The Geometry of the Universe was my first introduction to most of the
modem theories of quasar-galaxy evolution.  Along the way I have
thought about quasars, dust, suns, black holes and I now have an
obsession with pulsars.

The idea that small galaxies grow into larger galaxies seems quite
natural.

In this work Rourke presents a model for the universe with no need for
dark matter and no Big Bang.  

I obtained a copy of the book and was enthralled.  As an
under-graduate I had rarely spoken to Professor Rourke, other than to
let him know where I was living.

I plucked up the courage to contact him about the book and to my
immense delight it was the beginning of a wonderful correspondence as
he guided me through his perspective on the universe.

With no big bang, there is also ample time for galaxies to grow, by
slow acretion of matter to their central black holes.  Galaxies
giving birth to baby galaxies, which may one day grow into galaxies
themselves, or a globular cluster perhaps?

The Weak Sciama Principle
-------------------------

::

   A mass m at distance r from P rotating with angular velocity w
   contributes a rotation of kmw/r to the inertial frame at P.

   k is a constant.


The Sciama Principle is proposed, as an addition to General
Relativity, to explain galactic rotation curves without recourse to
dark matter.  In short, the reason stars at the edges of galaxies are
moving faster than general relativity says they should is because of
rotations induced by central black holes, dragging space time around
with them.

The same principle allows central black holes to absorb angular
momentum from inflowing matter and so there is no need for complex
acretion disk theories.

This is an important aspect of the theory.  It recognises general
relativity is a very successful theory and so proposes an extension,
which is to adopt the Sciama Principle.  

It is also just a theorem about the propogation of gravitational
waves: that their amplitude reduces as 1/r, where r is the distance
from the source.  This is widely accepted in the community and is
usually used to calculate the distance of the source, usually
expressed as redshift, with a Hubble-law.

Once there is a ripple in space-time, that ripple moves at the speed
of light, with amplitude reducing with distance.


de Sitter Space
---------------

The other key idea is that the Universe should have the Perfect
Copernican Principle: it looks pretty much the same everywhere you go
and has done for some considerable time.

de Sitter Space is a solution to Einstein's general relativity.  It is
the simplest possible, uniformly curved space time, and a natural
model to consider.

Due to curvature, we only see a window on part of a much bigger
universe.

Each galaxy we see bursts into our visible universe infinitely blue
shifted, then the blue shift diminishes as the galaxy moves
asymptotically to a Hubble law.

We see each galaxy redshifted for all but a small finite part of the
infinite time that we see the galaxy.

Are quasars baby galaxies?
--------------------------

de Sitter Space has a more complex relationship between distance and
redshift than a simple Hubble law, but it is not the whole story.

The Eddington sphere of a black hole, where much of the light is
produced, can be close enough to the black hole that the light is
gravitationally redshifted.


Little Red Dots too
-------------------