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What If Dark Matter Really Doesn't Exist?
sonar67 writes "According to The Economist: 'It was beautiful, complex and wrong. In 150AD, Ptolemy of Alexandria published his theory of epicycles--the idea that the moon, the sun and the planets moved in circles which were moving in circles which were moving in circles around the Earth. This theory explained the motion of celestial objects to an astonishing degree of precision. It was, however, what computer programmers call a kludge: a dirty, inelegant solution. Some 1,500 years later, Johannes Kepler, a German astronomer, replaced the whole complex edifice with three simple laws. Some people think modern astronomy is based on a kludge similar to Ptolemy's. At the moment, the received wisdom is that the obvious stuff in the universe--stars, planets, gas clouds and so on--is actually only 4% of its total content. About another quarter is so-called cold, dark matter, which is made of different particles from the familiar sort of matter, and can interact with the latter only via gravity. The remaining 70% is even stranger. It is known as dark energy, and acts to push the universe apart. However, the existence of cold, dark matter and dark energy has to be inferred from their effects on the visible, familiar stuff. If something else is actually causing those effects, the whole theoretical edifice would come crashing down.'"
If something else is actually causing those effects, the whole theoretical edifice would come crashing down.
As it should.
-Colin
It will be interesting to see how scientists who have staked their entire careers upon the existence of dark matter would react to the discovery that it does not in fact exist. Ideally an invalid theory is dropped, and a new, more "correct" theory is created. However, I have a feeling that a lot of people have invested too much time and effort into dark matter to let it go without some serious evidence.
My patience is infinite, my time is not.
We don't understand something fully? Wow... that's about as brilliant as deciding to cut my sandwich in triangles instead of in squares.
The truth is this. We have such a little understanding of actually governing laws that we can't begin to fathom it. However, that doesn't stop us in progression to learning. Just because this theory might not be right (and probably isn't) doesn't mean we are any less an idiotic species. We've been working on these theories for many millenia. One of them turning out to be wrong won't be a surprise... it's a probability. Without the wrong hypthosesis, we can never stumble onto the correct ones. Its Edison's, "Every time I fail, I know one more way how to NOT build it" idea.
...then 99.9999999% of the world won't notice. But it will be on CNN anyways.
So what if it doesn't really exist?
You can write a "hello world" program in most programming languages in under ten lines of code.
You could also write a program to synthesize speech to say "hello world" in an MP3, rip the MP3 to a wav file, and then write a speech-to-text engine to finally dump "hello world" to the screen.
Same idea here. Kepler's laws reduced a nightmarish tangle of mathematics to a three line "program", if you will. Out current model of how various things in our universe interact requires a degree in cosmology to fully grasp, and a PhD to do any meaningful work in. Imagine reducing that to one chapter of a freshman-level physics or astronomy course.
So, it matters for that reason. Unneccessary complexity slows down work in the field, and in the long run can actually prove counterproductive to the field as a whole (think about it - 1500 years wasted trying to make epicycles work).
Actually it will make a huge difference. Just look at how Bohr's model of the atom changed chemistry and particle physics. Or how Plank's quantum theory caused a revolution in the physics community. And one of the most famous examples of an upset in scientific theory is Einstein's theory of Relativity verses the Newtonian theories most commonly held at the time.
Each of these theories caused an almost immediate revolution in their respective fields which spread out to similar disciplines. Fast forward 20, 30, 50 years or more and a number of innovations and inventions appear which stem from these theories. If these theories had not been introduced then we would most likely not have had such an explosion in technology.
Just because we wave our hands and say something is out there doesn't mean that we understand it or can use it. If we know the true mechanism behind dark matter and wether or not it is just "hand waving" then we can apply that knowledge to useful applications. For example, it is assumed that this dark energy exhibits a repulsive force similar to gravity but opposite to it in direction. If we truly understand how this works then we might be able to apply that knowledge toward "anti-gravity" spacecraft, etc. On the other hand if there is some other cause for the repulsion then we would need to know IT'S mechanism in order to utilize it.
In the end, science is the quest for truth, not convenience. Just knowing that there is a certain effect is not enough. Scientists are not looking to solve the question of "what is that" but rather "why does that exist and how does it work". That is why it is important to seek out the true reasons behind the dark matter observations.
Sapere aude!
However in this case your comment is only slightly wrong and therefore I have some hope that my reply might be a useful contribution.
You are correct that mathematical proofs are based on axioms. However there is still a crucial difference between a mathematical proof and a scientific theory. A mathematical proof is an absolute certainty. Note that I am not claiming that the underlying axioms are certain. I am only claiming that the proof itself is certain.
To put it another way, mathematicians are never certain about their underlying axioms but they are absolutely certain that if those axioms hold then the result stated in the proof also holds. It's kind of like a building with indestructible walls but no foundation.
Scientific theory is a whole different kettle of fish. You cannot prove a scientific theory with absolute certainty. In fact it is not even clear to me how one can define certainty within the framework of the scientific method. You never have any guarantee in science that future observations will be consistent with past observations.
In science you can prove a theory in the sense of preponderance of the evidence. You can even sometimes prove a theory beyond all reasonable doubt. But there is no way to eliminate the unreasonable doubts. Any endeavour based on empirical observation suffers from the fundamental limitation that you can never be sure of the next observation.
Finally, regarding 1+1=2, the foundational proof of this fact using the standard propositional axioms of mathematics really does require 362 pages. You can see the 362nd page on the bottom half of this Russell's paradox site.
It isn't really amazing that they all give the same answer, because they all make the same assumption:
f = G.m1.m2/d^2
What if this is only a *very* good approximation for all normal purposes, and even for things as large as the solar system (in the same way that Newtonian mechanics is good enough for all earthly based stuff).
What if gravity doesn't quite work this way at galactic scales?
There was a piece in New Scientist last year making this exact point, and the researcher was able to explain most effects that are otherwise explained by dark matter, by slightly changing the theory of gravity.
Einstien did it for Newtonian Mechanics.
The real problem I see here is that the scientific method has been largely ignored. We observe the universe, we devise theorems to explain it, we test the theorems against other observations. If the test doesn't match reality, we assume that the theorem is wrong.
This doesn't occur with cosmology.
We observe the universe, we make theories, and when they don't fit, we assume there must be something wrong with the universe!