The title of this post comes from the bible:
“I clothe the heavens with blackness And make sackcloth their covering.” – Isaiah 50:3
I thought it particularly fitting as I want to talk about darkness. In particular Dark Matter and Dark Energy… And why I don’t believe in them.
Why would I lack belief in these things?
Simple. They can’t be seen. We don’t know exactly what they are. In fact we know very little about them except that science says they exist.
First things first though, a little background.
A little as one hundred years ago, the consensus was that the universe consisted of the galaxy we know as the Milky Way.
Then in 1922-23, Edwin Hubble identified something called the Cepheid variables, which are a class of pulsating stars. He determined that the relationship between their luminosity and pulsation period made them ideal indicators of distance.
All well and good, but when he then started looking at two spiral nebulae, Andromeda and Triangulum, he realised that they were not part of the Milky Way, they were too far away, and rather than nebulae, they were in fact separate galaxies in their own right.
He also famously discovered that the universe was so much bigger than previously thought and was also expanding. Every galaxy (or cluster of galaxies) were moving away from each other.
This and other discoveries, in conjunction with the advancements in technology lead to this image:
The numbers, I’m sure you’ll agree are staggering, quite literally beyond the scope of the human brain to comprehend.
“So what?” I hear you cry, “What has this to do with matter and energy both dark in nature?”
Bear with me… I’m getting to them.
In 1922, the Dutch astronomer, Jacobus Kapteyn first suggested using stellar velocities to infer the presence of extra material in space that was yet to be observed.
Then in 1932, Jan Oort, another Dutch astronomer was studying the motion of nearby galaxies and also realised that the mass in the galactic plane must be greater than was observed. However, his measurements were later discovered to be wrong.
1933 saw a man named Fritz Zwicky, a Swiss astrophysicist working at the California Institute of Technology, was studying a galactic cluster and came to a similar conclusion. His calculations were more accurate and he showed that the cluster had approximately 400 times more mass than coulld be seen.
The mass of an object in space can be determined by measuring how a body affects nearby bodies. For instance, the weight of the Sun is known to be 2 x 10^30 kg or 1.98892 Nonillion kilograms (a nonillion = 1,000,000,000,000,000,000,000,000,000,000)
We know this because it has been calculated using the velocities of the planets in our solar system and how much mass the Sun would require for those orbital speeds to be maintained at their varying distance from the Sun.
Using this same method, the mass of a galaxy can be determined by measuring how it affects nearby galaxies.
Zwicky, then became the first to name this missing substance, dunkle Materie ‘Dark Matter’.
Due to scientific investigation over the years, it is now known that the visible universe consists of only 4% of the mass of the universe.
That’s right, every galaxy, every star, nebula, pulsar, quasar, planet, moon, asteroid, gas cloud, dust cloud, black hole… Everything we can see makes up less than a 20th of the mass of the visible universe.
The thing about Dark Matter is that we can’t interact with it. We don’t yet know what it is. What the material is, it doesn’t seem to affect normal matter other than the gravitational effects associated with its existence.
Several investigations have looked into which fundamental particles could be involved, from muons or gluons to neutrinos.
A neutrino being a particle we know exists, but have difficulty examining simply because it doesn’t interact with normal matter. At any one time, billions and billions of neutrinoes fly through space and through the planet Earth. The mass of the the Earth has little to no effect on them. In fact, it has been calculated that in order to trap a neutrino we would need a wall of lead at least one mile thick.
We still don’t know what dark matter is, but we’re investigating.
So, we’ve had a little look at Dark Matter, let’s move on…
In 1998, Saul Perlmutter,Brian P. Schmidt and Adam G. Riess suggested that the universe was not only expanding, but that the expansion was accelerating.
Various measurements of cosmic background radiation, gravitational lensing and the large-scale structure of the universe has confirmed their theory, leading to their winning of the Nobel Prize for Physics in 2011.
The problem was that the acceleration of the expansion was in direct contradiction to the gravitational effects of dark matter on the the visible matter.
Further study showed that dark matter actually made up only 24% of the mass of the universe and this new unknown force made up the remaining 72%.
It was named Dark Energy.
Two proposed forms for dark energy are Albert Einstein’s cosmological constant, a constant energy density filling space homogeneously, and scalar fields such as quintessence or moduli, dynamic quantities whose energy density can vary in time and space.
So, we know it exists, but as with dark matter, we have no real idea of what it is, and once again, we are investigating.
I’ll bet you’re wondering why I don’t believe in Dark Matter or Dark Energy. After all, I’ve provided you with, if not complete evidence of them, but at least a starting point for you to continue your own study if you wish.
Allow me to explain.
Science made observations of the visible universe and hypothesised certain things. Just as in past history, religion made observations of the visible universe and hypothesised certain things.
However, unlike religion, science did not simply tell the population to believe what it had to say without question. Science did not put people to the sword for failing to believe what it had to say.
I accept that, even though we still don’t know what they are, dark matter and energy exist. Because contrary to the religious standpoint, science has produced credible evidence to back up its assertions.
I don’t believe in dark matter or dark energy because I don’t have to.