Tuesday, April 24, 2012

Dark Matter

Supposed distribution of dark matter in the galactic halo

Our series about ill-guided science would not be complete without discussing a very "dark" chapter of modern science - the topic of so called "Dark Matter".
After scientists found out that the measured density of matter in the universe could not explain its flatness and that there needed to be about ten times more matter than could actually be observed; that the observable matter could not explain intergalactic super-structures; and that galaxies rotated with such a high velocity that its matter would not be able to hold them together; it was obvious that there was something wrong with the existing models of the universe. But everybody had become so accustomed to the well-known models of gravity, the Big Bang and black holes, that nobody was willing to throw them over board so easily. Something needed to be done to save these beloved theories and reality could not be allowed to get into the way of such nice models.

So scientist introduced some mysterious variable into the equations. The "dark matter" was born. They could also have resorted to some supernatural power like a god who would keep things together and do what the missing matter in the universe was not able to do, but the term "dark matter" simply sounds more "scientific". People had already become used to things like "black holes", so "dark matter" fitted quite well into the faith of theoretical physics.
In fact "dark matter" has a lot of things in common with a god: First of all it is invisible. This is an important advantage, because it makes it difficult to disprove it. Second, since it is undetectable, you can give it any attribute you need to support your model of the world. So theoretical physicists were exactly able to calculate the amount of dark matter as 83% of the total matter in the universe, which was the amount they needed to save the existing models. Since there was no way to detect dark matter, there was also no need to measure this number, which is always quite convenient. Since nobody could see or understand this mysterious dark matter, the priesthood of theoretical physics had the sole authority to interpret and describe this esoteric substance.

Unfortunately some heretical astrophysicists have recently spoiled the fun for the theoretical physicists (http://arxiv.org/abs/1204.3924). They measured the dynamical surface mass density in the galactic neighborhood of the sun and found no indication for the presence of dark matter as common theories would suggest. This will probably not be the final death blow of "dark matter" and theoretical physicists will most likely come up with some adjustments to their theory, but it shows that a lot of those models of theoretical physics are just invented out of thin air and always circumvent any experimental proof.

If a measurement deviates a whole magnitude from the predictions of a theory, like the measured density of matter does, the normal reaction should be discarding the theory as useless. Why are theoretical physicists not reacting this way? If the observable matter in the universe is not able to explain the observable effect of gravity, then probably our theory of gravity is wrong. The scientifically correct attitude would have been to declare Newton's law of universal gravitation as wrong. 

F = G \frac{m_1 m_2}{r^2}\
Possibly wrong.
May be it is only an approximation for planetary distances but incorrect for interstellar or intergalactic scales.
We have no explanation for the surprising discovery that the universe expands at an accelerating rate, although gravity is supposed to slow it down. Perhaps gravity has a reversed effect over intergalactic distances. But this cannot explain, how galaxies are held together by such little matter. It seems that the effect of gravitation is higher than it actually should on a galactic scale. There are so many unanswered questions regarding gravity, that we should simply admit that we don't have a working model of gravity at the moment. 
Instead we invent theories of speculative objects like black holes and other singularities with arbitrarily extrapolated values of our flawed law of universal gravitation. May be there is an upper limit for the density of matter, perhaps in the magnitude of atomic nuclei, which is by coincidence also the density of a neutron star, an astronomic object that can actually be observed, different from black holes, which are just based on speculations. We even have theories about so called "Hawking radiation" that causes black holes to slowly evaporate and other descriptions of odd phenomena of singularities like wormholes, white holes etc. We have faster than light inflation of the universe in order to save the otherwise failed theory of a Big Bang, we have a string theory with up to 26 dimensions, of which only four are apparently observable.

When is it finally enough with such weird speculations? What does this have to do with science, which should primarily be occupied with explaining actual observations?
This has nothing to do with what science is supposed to be. This is at best some philosophical exercise. We need to bring back rationalism into scientific research. And we need to limit science to what we can actually observe. We should get our feet back on the ground, think about what we really know and only make research about subjects where we have an actual chance to find answers instead of inventing more or less unfalsifiable speculations.
Let's be honest. We have no idea how the laws of physics work outside our solar system. We have no idea about the origin or the future of the universe. We cannot jump to conclusions based on theories. We have to observe the world and then come up with possible models of our observations. As long as we haven't seen a black hole or some dark matter, we don't even need to ask a question about it.


  1. You write a lot of mambo jumbo about other's mambo jumbo; what's the difference ? The truth is there, no matter if we see it or not. (The Universe has no need of us) .
    If Einstein; realized all the science facts correctly, 100%; what would it profit him now anyways?

  2. I do enjoy your blog... I don't agree with every point you make in it, but I see the inherent value. Far too many people today walk the line of doctrine, even in scientific fields, while making no effort to think for themselves.

    Allow me to relay a comment I recently made on a YouTube video, where the discussion had wandered into a subject of religion vs. science. I dared to make the following comment:

    The Religious: There's this man, in the sky. You can't see him or touch him or hear him but... He sits on a throne and makes everything happen.

    The Scientists: There's this stuff, in the sky. You can't see it or touch it or feel it but... It is there, and it makes up 83% of the Universe. Without it our mathematical models for gravity fall apart. So, while we can't prove it exists, our models don't work without it.

    Pot... meet kettle.

    I was immediately crucified by a considerable number of people. Told I was stupid and that I have no right to procreate because I dared to disagree with the established doctrine of the scientific community. Many of them I will assume are arm-chair physicists. I am a student of computation, and occasionally an arm-chair physicist myself. But I'm always the first to note that I am not a physicist and that my own comments should be considered conjecture, even when logically valid.

    I had not heard of the Dark Energy & Matter theory before a couple of years ago. I don't spend a lot of time researching physics, but I can occasionally understand some of what is presented. I happened upon a program on the National Geographic Channel that attempted to explain the theory of Dark Matter to the layman. I think what piqued my interest was the featured scientists explaining that computers have only recently become powerful enough to effectively model gravity in a timely manner. Then he said something that I found genuinely shocking...

    I'm going to paraphrase here, "When we started the simulation we were baffled because our model galaxies fell apart in the time span of a single orbit. It was then that we knew there must be some other immeasurable substance out there to account for that missing mass."

    Huh? Your method doesn't work, so you solve for X and invent some mysterious and undetectable substance that plugs into that variable and fixes your model. Not only that, but suddenly this mysterious goo comprises 83% of the mass in the universe?! Have you considered, just for a moment, that something's wrong with the method itself?

    As I mentioned before my study is computation. Often when designing an algorithm, there's a lot of experimentation involved. When you try a function and the input is correct and the output is close to, but not exactly what you expect, then you may have overlooked something. If the input is correct and the output is way the hell off what you expect, say 83%; chances are better than not that there's something seriously wrong with the methodology. These scenarios aren't always the case of course. But, something that far out of bounds is usually telling.

    I'm am not a physicist, so my rationale may not apply. But, I find ideas of mysterious and immeasurable things highly suspicious in the general sense. While I can't say for certain that mysterious and immeasurable things don't exist, more often than not their application to a problem is the product of lazy or illogical thinking.

    1. This is exactly the point. It is about the scientific method. Of course the current models work, if you include enough arbitrary variables like dark matter, dark energy, inflation theory etc. But this is not how science should approach a problem.
      Then after all scientists wonder why the universe is so precisely fine-tuned and all the variables have exactly the values they need in order for the universe to work. And then they start speculating that there must be some unknown intelligent designer or they resort to the anthropic principle forgetting that it was themselves who fine-tuned these variables.