eLearning Collaborative

    During our interview with Malcolm Fairbairn a favorite
subject of mine came up, known as 'Dark Matter'. Leighann did a great job of
explaining this on one of her earlier posts, but what she did not get into was
the related topic of 'Dark Energy', so I am going to indulge you on my own
personal understanding of it.

     An assumption all scientists make, is that dark
matter has pretty much the exact same properties as regular matter, just
missing the ability to reflect or emit light energy. So how I am going to
explain this is in relation to a high pressure system in weather (or a change
in pressure between two rooms).

    When you have a high pressure system, there is obviously
a larger density of oxygen molecules per inch than in a low pressure system.
Now what these compacted molecules will want to do is find as much space as
they can, and move away from the high pressure system. This is what causes
wind. (You also notice this when you move between two rooms with a different temperature,
and there is a draft moving through the door. One room on either side of the
door has a higher pressure than the other causing molecules to try and move
from the high to low pressure) Well this is pretty much the same thing that is
happening to the universe. At the big bang, there was an infinitely large
amount of 'stuff' packed into an infinitely small space, so the 'stuff' that
was there very badly wanted to move away from all the other 'stuff' (I’m using
the word 'stuff' because we don’t know exactly what existed at the big bang).
This caused a very fast expansion! So as these particles expand, the density of
the universe will get smaller and smaller as all the matter is moving into more
and more space. So what we used to think to be true was that eventually gravity
will overpower this need for the matter to expand, and will slow down the
expansion to a stop and begin pulling it all back together. Yet from
observations made by several generations of scientists, the expansion is not
slowing down, but it is speeding up. So the idea of Dark Energy is supposed to
explain this.

    It explains it by saying that 4% of matter is visible,
20%-35% is dark matter, and 60%-75% of the universe is a sort of field that is
dark energy. So, since dark energy is more of a field than matter, it does not
become less dense as the universe expands. It stays the same density throughout
all of space, and throughout all of time. So what happens because of this is
the universe will never stop accelerating outwards, because the unchanging
field of dark energy will make the rest of matter continue to want to expand
outwards away from each other.

     Now, I really hope I didn't lose you during that,
because I'm not going to lie, I got myself lost several times throughout that.
So, please! If you have any questions on this, do not hesitate to send me an
email or post a reply!

    Thanks for reading! 

References