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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.
Dark Matter will be taught to school children as the Aether of 21st century science.
A theory of how things work is only as good as that theory's predictions. Ptolemy's model must have been very useful for predicting the position of celestial objects or it would have been put aside even 'longer' ago. It's only when a model is in direct conflict with observed data that it is in trouble: even if there is no formulated model that works with the new observations.
'Dark' energy and matter will only be in serious trouble when that model no longer explains observed data.
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).
knowledge of its existence and how much of it exists will determine whether or not the Universe eventually implodes on itself I think it's safe to say that our knowing ANYTHING about dark or exotic matter will have no effect whatsoever on the fate of the universe.
Any sufficiently simple magic can be passed off as mere advanced technology.
You can only make mathematical proofs if you accept some set of axioms that themselves cannot be proved (and thus must be taken for granted) as the foundation for your proof. As for 1+1=2, it can be proved directly using the basic axioms of arithmetic which neither are hard to understand nor require 300 pages to express.
First claim: Analyses of the WMAP data on the cosmic microwave background (CMB) show correlations with galaxy clusters that indicate the official analyses of the data are wrong. I find this highly unlikely. First, the effect of the hot gas in those galaxy clusters on the CMB is well known - it is called the Sunyaev-Zeldovich effect and perturbs the spectrum in a well-known way. Second, the official fits to the WMAP data use a consensus cosmology model with about 12 free parameters to fit a dataset of more than a hundred points... beautifully. Third, the consensus cosmology itself has been built up out of a huge array of other observations (supernova distances; Big Bang nucleosynthesis; the "weighing" of galaxies and galaxy clusters; the age-dating of globular clusters), all of which were pointing to the existence of dark matter (even within our own Galaxy!) long before WMAP was even launched. Fourth, modern theories of particle physics also give us good reason to expect the existence of dark matter particles, independent of any astronomical observations whatsoever. So WMAP has simply been the final nail in the coffin, and anyone who wants to overturn dark matter and dark energy has a great deal of additional work ahead of them.
Second claim: Measurements of the masses (actually, the luminosities and temperatures) of high-redshift galaxy clusters indicate a high fraction of baryonic mass, removing one of the justifications for positing dark matter. This finding is even more fishy-sounding. To understand this, realize that the group in question has deliberately chosen the most-distant and therefore hardest-to-study clusters to study, and adopted temperature-mass relationships that are calibrated in the local universe (and may not apply at these great distances) in order to find that their sample differs from the standard model predictions. Without even bothering to list all the ways in which they might be wrong, let me simply state that even if they are right there is a lot of independent support for the dark matter + dark energy picture that neither of these groups is addressing.
Rather than distract yourself by trying to figure out why the carefully constructed consensus cosmology might be wrong, then, I think it is more useful to examine the remarkable ways in which it has been proven right in the last few years. Altogether it is truly a wonder of the modern world - even if it may at some point be shown inadequate to the universe we live in.
-renard
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!
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.
Einstein's Special and General Relativity, Maxwell's Equations, and Schrodinger's Equation are all expressed in a few lines of equations. But you need extensive math and physics training to relate them to the familiar world around us. Simple doesn't mean easy. Theoretical physicists are already busily looking for theoretical formulations in which dark matter and dark energy arise naturally, rather than as a kluge. Of course, if the original observations turn out to have been misinterpreted, they may be wasting their time.
I used to think it was crazy. But then I imagioned what life would be like for a process on a Linux box. In some respects, the system never changes. In other respects, as chunks of the system are refined an upgraded, previously famliar systems take on more complex, and at times, incomprehesible behavior.
A process would be oblivious to the universe stopping and restarting with a new kernel. (Assuming the system had a suspend-to-disk function.) You would only be able to understand the universe indirectly through it's behavior, not through reading it's source. And assuming you could read parts of the source, it is always being updated and revised.
It the process under Linux is too strange, how about a citizen under a government. Laws are just another form of code, and they too are every changing. Some parts are like the Constitution, broad in scope and largely set in stone. Others are like legal precidents, situation specific and sometimes arbitrary.
Ok, time for more coffee.
"Learning is not compulsory... neither is survival."
--Dr.W.Edwards Deming
Well, a force that we could never observe, we could never test the existence of. Sure, you could postulate it, but it wouldn't help the theory at all -- you wouldn't be able to tell if your theory was right or not. You might as well say that tiny invisible demons are causing strange things to happen...
"Destroy science and religion. Science would re-emerge exactly the same; but not religion." - Penn Jillette, paraphrased
All species are intermediary species.
Computers are useless. They can only give you answers.
-- Pablo Picasso
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!
1) Pascal's wager doesn't work - lots of religions make countervailing or contrary claims to being correct. The question that most people have to decide is not whether to have faith in anything or not, but whether to believe in Christanity or Hinduism or Judaism or Islam or... Many of these choices are exclusive or contradictory, so believing in something won't necessarily save you - only believing in the right thing will. In addition, believing in something excludes options from the here and now - if you hold a religious belief, you must act consistently with it, excluding some possible actions that might benefit you. Pascal's Wager is not cost-free, and since its benefits are unclear (if all beliefs lead to the same place, Pascal's wager holds; if some beliefs lead to Hell (or some other bad place) then the value of choice may be much smaller and on the order or the cost of choosing and the opportunity costs of actions you cannot do), it isn't really a very good argument for religious belief.
2) Science and religion are not exclusive unless one forces them to be. Science takes a pragmatic view of the world - what effects we can observe or measure are those of consequence to science. The immeasureable is not science's purview. Religious beliefs ask different, perhaps broader questions: What are we doing here? What do we do with our lives? How does everything work? Science can be considered a subset of this. Multiple religious beliefs may be consistent with a physical phenomenon - the things that distinguish them exist in a place science can't get to and thus has no legitimate say in. The problems occur when religious and scientific claims occupy the same ground and are contrary. In this case, science usually wins because it can be tested, whereas religion depends upon claims that cannot be tested (but which can only be trusted).
In my opinion, it is not the "anti-religionists" who have betrayed us, but a subset of religionists. Religion and science have existed side by side for some time and were not considered inconsistent. In the last few hundred years, some religious folk have tried to "prove" their beliefs by misusing logic and science to their ends (creationism/intelligent design/creation science, for example). Trying to prove the unprovable only further hardens the demands of people for proof before they will believe, undercutting the faith; after all, if the people who claim to most strongly believe something require proof to believe in it, how much faith can they really have? There is also the bonus of trying to force people to have a faith whose value derives from chosen belief (thus destroying the object of belief for others). In addition, the likely purpose of the logical legerdemain (to compel others to behave as one would like) only serves to alienate those who would otherwise be quietly accepting of the faith of others. Vehement (and sometimes illogical) people who don't believe in religion probably come at least in part from this.
Actually, yes, Occam's Razor can be considered to be a mathematical conlusion of Kolmogorov Complexity Theory.
Briefly, Kolmogorov Complexity Theory is the study of the compressibility of strings of symbols. E.g., consider the three 10 digit strings "0123456789", "4294967296", and "5286354993". Which is most compressible (or, almost equivalently, easiest to remember)? Well, the first is obviously easy to remember (compress): count from 0 to 9. The second is (not as obviously) perhaps even easier to remember (compress): it is 2^32. I believe the third to be difficult to remember (because probably it has to be completely memorized - I typed it in "randomly").
Now suppose we consider infinite strings instead of finite strings, and we consider all computer programs that print out the first n symbols of a given infinite string. In Komogorov Complexity, Occam's Razor is equivalent to the idea that the shorter the program that prints out the first n symbols, the more likely it is to print out the correct (n+1)th symbol. This can be made completely precise, and then "Occam's Razor" is a provable conclusion.
One way to think about why Occam's Razor is true: shorter theories are less likely to have arbitrary, extraneous features which imply incorrect conlusions (predictions).
It is quite obvious to me that the Earth is motionless and the Sun rotates around the Earth. Seems like a nice simple theory.
It is a nice simple theory, and it's one that worked for humanity for quite a long time. However, that theory becomes less and less simple as you try to explain the motion of the moon, the planets, the planet's moons, comets, astroids, and other stars.
The point is, what is "obvious" and "simple" depends a lot on what you think and what you know and is by not necessarily universal.
Actually, I'd say that the simpliest theory is entirely dependant on what you know and is almost certain to change as you learn new things.
We hope your rules and wisdom choke you / Now we are one in everlasting peace