Sunday, May 26, 2013

Shedding Light on Dark Matter

Sometime in the 17 th century, a man was supposedly hit on the head by an apple, ripe, that had detached itself from the tree he had been
sitting under. This story should be familiar to any self-respecting
physics student–myself included-. How true this story is, or the less
painful version of him merely observing the very hard fruit falling to
the ground, is subject of little importance. But the events that
followed have affected every aspect of how we view the world today.
We see stuff fall to the ground all the time, it really is no biggy. I
mean, it's just a fact of life; things will fall. In that fateful
century, however, in an unplanned vacation induced by an epidemic of
the plague that ravaged parts of Europe, a very smart scholar used
this time very wisely and out of it came the answer to the most
unasked question of all time: why does stuff fall down? Newton, today
known to many as the greatest thinker of all time, pondered this
question (in more formal English).
After countless hours he came up with a very nifty equation, stating
how gravity is a force that pulls stuff together, and how the strength
of this force decreases by a square of the separation of these two
objects. He also explained the motion of the planets and that was
that. Well, it's all good until you ask the question: what is gravity?
Of course, it is a force that pulls objects together, thus creating
the effect of the less massive one falling toward the one with greater
The trouble with this answer is that it just doesn't explain what
gravity is, it just explains what is does. Sort of like explaining
wind with the bending of trees. Einstein came to the rescue with his
famous theory of general relativity which explained how massive
objects distort the space-time around them, thus explaining the motion
of objects in such gravitational fields. He proposed another way of
looking at this force and in this way solved a long standing riddle of
the peculiar orbit of Mercury.
It seems there is an adversary of this universal force, a force that
does the complete opposite of what we've known gravity to do; it
pushes things apart. After the expansion of the universe was
discovered, an even greater anomaly was observed. The expansion of the
universe was expected to slow down but the discovery that this
expansion is actually accelerating, caught those who observed it by so
much surprise that at first they thought they'd made a mistake
Observations have shown that there's stuff literally appearing out of
empty space and pushing galaxies apart. It's an energy that pushes
incredible masses apart; we literally have no clue what it is, despite
studying it for over a decade. It's so illusive and so little is known
about it, save its effects, that it has been termed: Dark Energy. Not
related to the enigma of Dark Matter, its sexy adjective reminds us
how little we know about it.
In a recent scientific endeavor, a very sensitive satellite was used
to scan through the sky in all directions, in search for what is
essentially the afterglow of the Big Bang. The result was a dirty
looking rugby ball of a map that is the holy grail of cosmology known
as the Cosmic Microwave Background. Now, it gave many results of great
importance that as I am typing this I am contemplating a draft of the
column solely based on these topics.
Now, one part of the result shows that dark energy makes up 68.3% of
the universe, leaving dark matter being 26.8% and normal visible
matter a mere 4.8%. I find it fascinating that this stuff, this force,
this energy we know so very little about makes a bulk of the universe.
This mystery of dark energy is just one of many that keep me curious
and reminds me of how much more there is to know out there. The
universe holds many more secrets than we thought, and the more we
know, the more we realize how little we do know. For every one
question we answer, many more questions appear.
Now is an excellent and very exciting time to be an astronomer, and a
South African one at that. Also, being a science journalist and
enthusiast puts one at the forefront of what projects such as the SKA
project will produce regarding this anomaly and many more mysteries it
will answer, and many, many more it will create!
And by 'we', I am referring to all those curious and have insatiable
appetites to know more.

No comments:

Post a Comment