FRom The Technology Review website:
http://www.technologyreview.com/blog/arxiv/25492/
Tuesday, July 27, 2010

A new cosmology successfully explains the accelerating expansion of
the universe without dark energy; but only if the universe has no beginning and no end.

As one of the few astrophysical events that most people are familiar with,
the Big Bang has a special place in our culture. And while there is scientific
consensus that it is the best explanation for the origin of the Universe, the debate
is far from closed. However, it's hard to find alternative models of the Universe
without a beginning that are genuinely compelling.

That could change now with the fascinating work of Wun-Yi Shu at the National
Tsing Hua University in Taiwan. Shu has developed an innovative new description of
the Universe in which the roles of time space and mass are related in new kind of relativity.

Shu's idea is that time and space are not independent entities but can be converted
back and forth between each other. In his formulation of the geometry of spacetime,
the speed of light is simply the conversion factor between the two. Similarly, mass
and length are interchangeable in a relationship in which the conversion factor
depends on both the gravitational constant G and the speed of light, neither of
which need be constant.

So as the Universe expands, mass and time are converted to length and space
and vice versa as it contracts.  This universe has no beginning or end, just alternating
periods of expansion and contraction. In fact, Shu shows that singularities
cannot exist in this cosmos.

It's easy to dismiss this idea as just another amusing and unrealistic model
dreamed up by those whacky comsologists.

That is until you look at the predictions it makes. During a period of expansion,
an observer in this universe would see an odd kind of change in the red-shift of
bright objects such as Type-I supernovas, as they accelerate away. It turns out,
says Shu, that his data exactly matches the observations that astronomers
have made on Earth.

This kind of acceleration is an ordinary feature of Shu's universe.

That's in stark contrast to the various models of the Universe based on the Big Bang.
Since the accelerating expansion of the Universe was discovered, cosmologists
have been performing some rather worrying contortions with the laws of physics
to make their models work.

The most commonly discussed idea is that the universe is filled with a dark energy
that is forcing the universe to expand at an increasing rate. For this model to work,
dark energy must make up 75 per cent of the energy-mass of the Universe and be
increasing at a fantastic rate.

But there is a serious price to pay for this idea: the law of conservation of energy.
The embarrassing truth is that the world's cosmologists have conveniently swept
under the carpet one the of fundamental laws of physics in an attempt to square this circle.

That paints Shu's ideas in a slightly different perspective. There's no need to abandon
conservation of energy to make his theory work.

That's not to say Shu's theory is perfect. Far from it. One of the biggest problems
he faces is explaining the existence and structure of the cosmic microwave
background, something that many astrophysicists believe to be the the strongest
evidence that the Big Bang really did happen. The CMB, they say, is the echo
of the Big bang.

How it might arise in Shu's cosmology isn't yet clear but I imagine he's working on it.

Even if he finds a way, there will need to be some uncomfortable rethinking before
his ideas can gain traction. His approach may well explain the Type-I supernova
observations without abandoning conservation of energy but it asks us to give up
the notion of the Big Bang, the constancy of the speed of light and to accept a vast
new set of potential phenomenon related to the interchangeable relationships
between mass, space and time.

Rightly or wrongly, that's a trade off that many will find hard. Let's hope Shu sticks
to his guns, if only for the sake of good old-fashioned debate

Ref: arxiv.org/abs/1007.1750:
Cosmological Models with No Big Bang