THE BEGINNING AND THE COSMIC
EVOLUTION ( Page 3) |
|
| How do we explain a universe that beats gravity and
keep on expanding instead of slowing down? What do we do to fit this
new observation into our model of the cosmos? The easiest way of course
is to bring back the discarded lambda. Einstein’s cosmological
constant was not a blunder after all. This repulsive force acting
in empty space keep pushing the galaxies apart, overcoming the gravitational
pull. This is what makes the expanding universe accelerate. Problem
solved and everyone happy? Not quite. When lambda fitted in comfortably
into the Big Bang model of the universe, omega began
to cause problems. Omega stands for the material density of the universe
and its value depends on the total mass of all the matter that makes
up the whole universe. Einstein had predicted three possible shapes
for the universe depending on the value of omega.
The universe will be flat if omega equals one, open
or saddle-shaped if omega is less than one and closed
or spherical if omega is greater than one. It was
also believed that the fate of the universe depends on its shape. |
| An open universe will keep on expanding forever and
a closed universe will fall back on itself to end in a big crunch
while a flat universe will eventually stop expansion but will not
move backward to cause the crunch. In other words “density determines
destiny”, as one scientist put it. To assess the density of
our universe the value of omega was recently estimated
by observing the effect the matter of the universe had in bending
the cosmic background radiation, (CBR), the microwave radiation at
3 K, the telltale remnant of the Big Bang. These observations confirmed
the critical density, omega to be one, leaving a
flat universe. So far so good. But the troubles were not over yet. |
| Dark Energy |
| Here is the dilemma that faced the physicists at the
turn of the millennium, the dawn of the twenty-first century. The
fluctuations in the Cosmic Background Radiation pointed to a flat
universe. Yet the latest, most reliable and accurate estimates of
the total mass of the matter in the universe, including all the exotic
forms of matter does not come anywhere near that needed for the critical
density. The estimates show that the total mass can account for only
1/3 of the total mass required. Where do you go for the rest of the
mass needed for the universe to be flat? |
| So we go back to good old Einstein who had taught us
the principle of the equivalence of matter and energy through the
equation E = mc2. And thus we get the new notion that our universe
is made of one-third matter and two-thirds energy. But this is not
like any of the ordinary forms of energy such as heat, light, microwave
radiation etc. This was christened the Dark Energy: dark, because
it cannot be detected, and energy, because it is not matter. To have
the desired effect it has to be either matter or something equivalent
to matter, which is energy. But in reality this does not sound like
either matter or energy. But for argument’s sake let us acknowledge
the existence of ‘dark energy’ that substitute for two-thirds
of the matter in the universe. Still it is not smooth sailing for
the cosmologist. |
| Physics or Metaphysics |
| For one thing, this concept of dark energy is not something
that can be subjected to the common tools of physics, to be detected,
measured, transformed or studied otherwise. This borders the mythical
if not spiritual. Many noted physicists are not happy with the idea
of dark energy for this reason. Secondly, the ratio of matter to dark
energy needed to maintain the present state of the cosmos; the ratio
1: 2 is the least probable one of an infinite number of options according
to some. Hence this is unbelievable to many of them. To explain this,
some suggest that this form of dark energy has the ability to communicate
with matter and its quantity is self-determined according to the needs.
Does it not sound like an immense force with consciousness? |
|
