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The Dark Matter/Dark Energy Problem
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The Dark Matter/Dark Energy Problem The question of the existence of dark matter and dark energy represents the greatest challenge our understanding of the physics of modern cosmology. The present argument states that both have exist, or there is something seriously wrong with our present understanding of physics. I tend lean towards the latter suggestion, simply because the notion that something has to exist in order for the universe to make sense from our present perspective is not a scientific argument. It smacks of the old religious claim that the existence of a watch automatically implies a watchmaker. Effectively, it becomes an argument from ignorance that may well be true, but science can not allow itself to accept arguments founded on faith. If dark matter does exist, it should be detectable. The means of doing so are complex and would require explanations beyond the scope of this present piece. Perhaps I will tackle that at a later date. Suffice it to say that at least at present, numerous ingenius methods have been incorporated in the search, all have yielded extremely disappointing results. There has never been any detection of the expected signals from dark matter above the expected<b> background </font></b>noise. In effect, the search for dark matter has been about as productive as the search for Sasquatch. the circumstances might expect a greater degree of skepticism, but the nonexistence of bigfoot doesn't threaten any modern, cherished principles in biology. However, dark matter does generate its share of critics. I am among them. Some new and interesting proposals have been offered that do challenge some basic concepts of physics without rewriting the entire collection of physics texts . Gravity has always been regarded as one of the 4 fundamental forces of nature, by far the weakest, but exerting its influence over the greatest distance. But one new proposal suggests that we might need regard gravity in an entirely different way, and consider its relationship entropy. In effect, perhaps we need stop thinking of gravity as a fundamental force of nature. Entropy stands as perhaps the most poorly understood concept of physics, a point to which I will briefly return later. But in order to clarify what is meant by entropy, let's explore what it is as briefly as possible. The description of entropy that is generally offered is an explanation of the laws of thermodynamics and, put very simply, entropy is the unusable part of any system, for instance, the waste heat generated by your computer. This is a decent description, but let's try a different . Imagine a brand new deck of cards. You take them of the box and describe the order of the cards in the box. You could note that the 2 jokers are on top, followed by the all of the spades beginning with the Ace, then the King, Queen, Jack and the numbered cards in descending order from down 2. That suit is followed by the hearts, clubs and diamonds all in the order. That is all the information required describe the initial order of the cards in the deck. Now, shuffle the deck a of times and the of information that will be required describe the order of the deck will be considerably greater. In effect, you may have list the position of every single in the deck. The act of shuffling the deck has added entropy the system, increasing its disorder. The more information it takes describe a system, the more entropy it has. Entropy is essentially the tendency of systems proceed from order disorder. A recently published paper suggests that thermodynamics is related information through the holographic principle as a model for the universe. The information contained in a region of space depends on the arrangement of objects within that region and moving objects, which are effectively everything in the universe, change the entropy within the region. This creates an entropic force that acts exactly like gravity. From the basic idea of information entropy, all of Einstein's equations of general relativity can be precisely derived. This is an elegant way resolve the problem of why gravity just doesn't fit very well into quantum physics. But it doesn't get us entirely of the woods with the problems that the suggestion of dark matter and energy seem to solve . For thing, since entropic gravity seems behave precisely like general relativity, there is no way experimentally distinguish the 2, thus it can not be established as a superior theory. There is also a problem with trying make the model work in a closed system of masses. The existence of entropic gravity works if you place some very bizarre constraints on the entropy within the system. But there is at least an interesting suggestion that gravity, dark matter and dark energy might all be connected through entropy. additional problem has be addressed. This emergent gravity simply doesn't do a very good job of addressing large scale effects in the universe, such as the clustering of galaxies. Dark matter and dark energy address that phenomenon quite elegantly, but the question would be so much easier if they would do us the favor of allowing themselves be detected. Still, the notion that thermodynamics and gravity are connected at a deep level is exciting, and something cosmologists are likely be addressing energetically in the coming years. Now, let's step back for just a moment and briefly discuss the most misused principle of science in lay discussions, the second law of thermodynamics. Deniers of evolution frequently cite the second law as proof that evolution can not occur. The second law basically states that in a closed system, order will proceed toward disorder. Since the evolution of life from simple to complex represents a trend towards greater order, evolution must be a violation of the second law, in their view. This argument fails spectacularly on 2 levels. First, they ignore an important aspect of what the second law states: That we must be describing a closed system. Life on Earth is, by no means, a closed system. The true closed system we know anything about is the universe itself and I frequently question whether or not our universe is a truly closed system. The Earth receives input daily, hourly and by the second and microsecond from many other sources, most importantly, the sun. While the second law does note that systems tend proceed from order disorder, there is nothing in the second law that states that subsystems within a greater system can not become more orderly, providing that the overall system is proceeding towards disorder. Let’s return for a moment, to the example of shuffling our deck of cards. Starting from a precise order, every shuffle increases the overall disorder, or entropy of the deck as a closed system. HOWEVER, it is entirely possible that each successive shuffle may be increasing the order in specific parts of the deck. Further, the fact that the shuffler is expending energy shuffle the deck is part of the overall system. The deck itself is not a closed system. In our case, might argue that life on Earth represents a trend towards order, but the Earth-sun system is constantly increasing in disorder, since entropy within the sun is increasing much faster than order is being created on Earth. Second, the argument that evolution is a move away from disorder may not be a well defined claim. Since the present structure of the Earth's biosphere is considerably more complex than it was at a time when it was dominated by single cell organisms, it can easily be noted that the entropy of the system has increased significantly since it takes more information to describe the system. On either or both counts, the critics of evolution fail to understand the science they are mistakenly attempting to use to justify a bad argument. |
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