Have you ever wondered how scientists can talk so confidently on dark matter and dark energy when we simply cannot observe or study it at all? The truth is that we still do not completely understand dark energy. We only know for sure that it exists because of the way in which the universe expands. Let’s not forget the plethora of evidence that it leaves in its wake that points towards it too.
What we know for now though is that where there is pure vacuum of space, there exists dark energy and dark matter with a constant density and this is for now more than enough for our understanding in this article.
Empty Space Plus Vacuum
There was a time back billions of years ago when matter had more density than dark matter. Back then things were so cramped together that the universe and its expansion was influenced only by matter and its high density. It did no matter than dark matter has a fixed density back then. This continued until the density of matter throughout the universe was higher.
But then as expansion continued, density of radiation and matter became less and less dense. Until about 5 billion years ago when it finally fell below the constant density of dark energy because it held its value with perfect consistency. The moment dark energy overtook the universe, the entire game changed. Because it kept a perfect density and the density of matter continued to drop, the universe did not just expand but accelerated ever since. It is this accelerated expansion that helped form galaxies. Instead of clumping together further, they began to move away from each other leaving behind empty space where dark matter thrived. Basically, our current knowledge points clearly to the fact that galaxies will no longer form as they move too fast for any meaningful interactions.
This leads to a dilemma. What happens in the distant future when matter and its density is so trivially small against the constant density of dark matter? In the far past, matter was so dense that dark energy did not matter. The same will happen with matter when it spreads so thin that it will have a density ridiculously low as opposed to dark energy.
We currently live in an age where dark energy is about three quarter of the total universal build up where as dark matter takes up one quarter with regular matter being a negligible amount. Is it possible that there is more than meets the eye? Truth is that no Earthly laboratory can ever decipher the true interaction between dark forces. They might have ways to balance each other or keep a check on the other. It is equally possible that this may not be the case. We simply aren’t educated enough at the moment to venture this kind of a guess. It all looks a bit dark at present, no pun intended!