Dark energy, dark matter and atoms

The recent discoveries, astrophysical measurements and astronomic observations have led over the time to a formulation of the cosmic triangle theory of the Universe which includes three major disproportional constituencies such as light matter (4%), dark matter (22%) and dark energy (74%). This can be true noting a non-linear composition of the world where we live. Besides measurements of the anisotropy (temperature fluctuation) of the cosmic microwave background radiation (CMB), a remnant of the Big Bang, suggest that the Universe is flat, rotating and expanding at an accelerated pace while having in its center a supermassive black hole. But the fact needs to be acknowledged that more is unknown than known creating endless new mysteries which most probably cannot be solved only with the help of science. That is why cosmology as a science successfully combines through times ( from the pre-historic epoch through the Dark Ages, Renaissance, Enlightenment to modern times of the industrial and scientific revolution) elements of religion, art, science and philosophy to grasp fully the true meaning, essence, structure and composition of the God’s creation called our universal home.

The cosmic triangle theory eliminates to a certain extent other existing popular models, such as a high-density Universe that is slowing down and will eventually re-collapse annihilating itself because it is full of matter and the attractive force of gravity pulls all matter together, as well as a nearly empty universe with no dark energy at all and low mass which means that it never stops expanding. While the evidence from galactic clusters shows that mass density is low, supernova data for acceleration indicates that dark energy as a cosmological constant must be abundant. This strongly suggests that the standard inflationary scenario is on the right track based on one of its key commonly accepted predictions about a flat universe.

During numerous scientific developments various types of dark energy (this term was coined by cosmologist Michael Turner) have been proposed, including a cosmic field associated with inflation; a different, low-energy field dubbed “quintessence”; and the cosmological constant, or vacuum energy of empty space. Unlike Einstein’s famous fudge factor, the cosmological constant in its present incarnation doesn’t delicately balance all-attractive gravity in order to maintain a static universe; instead, it has a “negative pressure” that causes expansion to accelerate. Saul Perlmutter, a leader of the Supernova Cosmology Project headquartered at Berkeley Laboratory and one of the initiators of the Beyond Einstein project maintains that dark energy actually fills the cosmos.

Dark Energy

Based on the gravity theory proposed by Einstein space is not an empty void but has some important properties which include that more space can come into existence and that space as such constitutes a cosmological constant possessing its own “inner dark” energy. Because the latter is a property of space itself, it would not be totally diluted as space expands. Based on this premise it is feasible to point out to a proportional correlation between space and such type of energy which cause the Universe to expand ever faster after a certain moment in time. Unfortunately, it is unexplainable using the theory of relativity why this cosmological constant should even exist in reality and possess exactly the right value to cause the observed acceleration of the Universe. In this regard another explanation for how space generates energy is of course associated with the quantum theory of matter. In this theory, “empty space” is actually full of temporary (”virtual”) particles that continually form and then disappear (The Higgs particles of visible matter and WIMP particles of the invisible, ”dark” matter). However once physicists attempted to calculate exactly how much energy this would give empty “void” space, the answer came out 10120 times which is unrealistically big. One more explanation for dark energy is that it is a new kind of dynamical energy field which permeates porous cosmic space but whose effect on the expansion of the Universe is quite opposite of that of matter and normal energy. This is named “quintessence,” although a mysterious one from the point of its existence and interaction.

Obviously more high quality information and improved data is required to decide between dark energy possibilities and to solve this God’s squander. The answers might be provided by The Beyond Einstein Program and the Joint Dark Energy Mission (JDEM) of NASA and the US Department of Energy. Both missions’ aims are to understand and analyze an evolution of dark energy in order to determine whether it is a property of empty space or whether it is a dynamic force field that evolves in space and time. This, in turn, may enable cosmologists to predict a continuous expansion of the Universe forever or its likely collapse back upon itself in a Big Crunch someday in a distant future. No doubt, it will also probably help expand our knowledge about the physics of elementary particles on a subatomic level as well as the origin and nature of our Universe.

Einstein’s cosmological constant seems to be the most economical explanation of this phenomenon although no fundamental rules can be used to tackle this physical parameter which is very small but not equal zero. In this regard one of the reasonable proposals to the extent may be a theory of multi-verses that presents constituencies of one Universe as strings or membranes explaining in principal all forces of nature as well as an existence of billions other juxtaposed verses. Many scientists, however, feel uncomfortable about this possibility or “cosmic mess” and put forward their own hypothesis. Among them are Edward Witten of Princeton, Lawrence Krauss of Case Western Reserve University, Matt Mountain of the Institute for Advanced Studies in Princeton and Brian Schmidt of the Australian National University and others.

Dark Matter

Based on this theoretical model of a composition of the Universe the second “inexplicable” element is dark matter (or invisible mass) which was predicted by Fritz Zwicky of the California Institute of Technology in 1930s who indicated that clusters of galaxies obviously missed some visible matter to be held gravitationally together. This type of matter is 5 times more by mass than visible material composed of gas, cosmic dust, stars and planets that we can see and dark clouds of normal matter made up of particles called baryons which can be detected due to their absorption of radiation passing through them. At the same time dark matter is not antimatter since no unique gamma rays are produced when antimatter annihilates with matter. And finally, it is not large galaxy-sized black holes because of an observation of many gravitational lenses. Dark matter does not reveal its presence by emitting any type of electromagnetic radiation. It emits no infrared radiation, nor does it give off radio waves, ultraviolet radiation, X-rays or gamma rays. However, at the moment, there are still a few viable dark matter possibilities.

The above-mentioned baryons could still make up the dark matter if it were all tied up in brown dwarfs or in small, dense chunks of heavy elements such as massive compact halo objects, or MACHO. They are often considered to be “gravitational microlenses” which curving or bending light from a distant background star in a nearby galaxy, for instance Large Magellanic Cloud (LMC). It increases the brightness of the star light by bending it in our direction for a short time when MACHO passes by. Depending on its mass and distance from Earth, this period of brightening can last days, weeks or months. The form and duration of the brightening caused by this microlensing “light curve” could be well predicted by theory and searched for as a clear signal of the presence of MACHO dark matter. In the framework of The MACHO Project of the Lawrence Livermore National Laboratory , the Center for Particle Astrophysicsin the United States and the Australian National Universityit was proved that there is a population of MACHO objects in and around our Milky Way galaxy that could comprise as much as 50% of its total (baryonic/normal-matter) dark matter content.

Nevertheless the most commonly recognized opinion today is that dark matter doesn’t consists of baryons at all, but rather is made up of other, more exotic and very elusive particles like axions or WIMPS (Weakly Interacting Massive Particles). These elementary subatomic particles seem to be immune to any forces of nature, including gravity and electromagnetism, and so travel freely like ghosts throughout the Universe. Proving their existence would solve a mystery about the identity of dark matter in the cosmos and might solidify the attempts of scientists to unify the four fundamental forces of nature which appears a rather difficult task now.

Theories that postulate the unification of the strong, weak and electromagnetic forces are called Grand Unified Theories (GUTs). Theories that add gravity to this mix and try to unify all four fundamental forces into a single force are called super-unified theories. Meanwhile a theory that describes the unified electromagnetic and weak interactions is called the standard electroweak theory. It is important to specify that grand unified and super-unified theories remain theoretical speculations that are as yet unproven, but there is strong experimental evidence for the unification of the electromagnetic and weak interactions in the Standard Electroweak Theory. Furthermore, although GUTs are not proven experimentally, there is strong circumstantial evidence to suggest that a theory at least like a Grand Unified Theory is required to make sense of the Universe. Besides it appears that among all four forces gravity always wins and is most influential.

WIMPs are of great interest for astronomers and physicists because they make up the dark matter, on the one hand, and are elementary particles, on the other, which should have heavier but so far undiscovered counterparts based on the theory of supersymmetry. To prove all these hypothesis several projects have been undertaken recently. Thus, DAMA/LIBRA project was initiated in 2000 in the University of Rome under the leadership of Rita Bernabei which has produced thus far quite controversial results based on the analysis of faint flashes of light from sodium iodide detectors when Earth passes through a “cloud” or “wind” of dark matter particles while orbiting the Sun in summer and winter. During these seasons the extent and force of this “WIMPs wind” is different and that diversion might lead to a detection of these mysterious but quite important sub-atomic particles in the world structure. The other project claims that neutrinos might indeed have mass and also constitute dark matter. This hypothesis is analyzed through experiments using a detector in Japan, called the Super-Kamiokande. Also, an alternative to the dark matter theory is the Modified Newtonian Dynamics approach (MOND) which uses a modified version of Newton’s Second Law ( F=ma where F is force, M is mass and A is acceleration) and is aimed at the study of eight dwarf galaxies rotating around the Milky Way. According to Newton’s Second Law of Dynamics, objects on the farthest edges of galaxies should have lower velocities than objects near the center because of the gravitational forces. But observations confirm that galaxies rotate with a uniform velocity. Nevertheless some astronomers believe the orbital behavior of galaxies can be explained more accurately with MOND than by the rival, but more widely accepted, theory of dark matter which assumes that a halo of dark matter surrounds each galaxy, providing enough matter (and gravity) that all the stars in a galaxy disc orbit with the same velocity.

To sum it up one can claim that dark matter is known to exist through the gravitational effects it exerts on visible matter in the Universe. As our astrophysical and astronomic experimental researches become more sophisticated, and our understanding of large gravitational systems such as galaxies and clusters of galaxies comprehensively widens and grows, we will be sooner rather than later in a position to answer more of the questions that have faced us for years.

Atoms

Referring to atoms we talk about visible or normal matter which can be seen everyday in a form of galaxies, stars, planets, interstellar clouds, cosmic dust. As was mentioned above it constitutes only a small mass fraction (4%) of the total Universe. However several lines of evidence have shown that researchers are missing most of the visible material. Thus, calculations of the amount of hydrogen, helium and a few other light elements forged just after the Big Bang indicate that there should be much more of this material in nearby reaches of the Universe than have been found so far. Studies of gas clouds so distant that they reveal conditions in the early stages of the Universe also provide evidence for a much higher amount of visible matter in the intergalactic medium.

The other approach to visible matter consisting of atoms made up of sub-atomic particles

is that dark matter is probably a main product produced by the Big Bang while visible matter is a by-product or a waste generated during the interactions between dark energy and dark matter in a state of expansion. In this case scenario the former provides the energy of motion while the latter a required material in order to generate visible matter with positive mass and charge/energy.

In any case the basic structure of normal matter consists of molecules containing atoms composed of elementary particles named protons, neutrons and electrons. The first two are called the “hadrons” and are made of odd sub-structural things: quarks and gluons which might include fundamental sub-elements called the Higgs bosons or particles. Besides each particle has a counterpart based on the supersymmetry theory. Thus, electron might have a hefty partner referred to as selectron, muon – smuon, quark – squark, etc. Many of those supersymmetric partners could be unstable, but the massive Higgs particle having the mass almost 200 times the mass of proton may be stable enough to describe the very basics of our Universe which has obviously its roots in the minuscule world of sub-atomic elementary particles and forces because the cosmos we see was once smaller than an atom (a singularity). That is why particle physicists speculate about cosmology and cosmologists talk about particle physics: our entire Universe emerged from things that happened at the smallest imaginable scale as the Big Bang theory postulates that the known Universe once had no dimensions at all-no up or down, no left or right, no time and no laws of physics beyond our vision. Therefore, when talking about matter (or nature) it is feasible to consider first and foremost fundamental elements of matter, the interactions between these constituents and the creation and expansion of space and time with their proper assistance and help.
This paramount task might be solved within a juxtaposition of the Newtonian laws, the theory of relativity and the quantum physics which together could explain the irreducible randomness of individual events, natural complementarities and general evolution of matter.

Science having the actual epistemological privilege of to be provisional itself continues to discover more fundamental elements (75 particles are known thus far) which help to understand completely a uniqueness of matter and to unite a wider breadth of the Universe. More and more theories are put forward with this aim. For instance, the string theory postulates that there are even smaller elements governing all aspects of our Universe and unifying the forces. In this sense it is quite possible that this cycle might be an endless regression, each element being built on more fundamental elements down to an infinitely identical ether holding together everything in the nature. This is of course mere philosophy at a certain scale, but when dealing with near-singularities such as the Big Bang or black holes it could suggest an absolute physical model would be infinitely complex to solve beyond a certain scale of physical observations or mathematical calculations. However a satisfying theory of everything could be a mixture of the string and the loop quantum gravity theories which might be an exact, “mirror-type” reflection of structurally complex reality or just a result of wild and sick imagination. In fact, in studying visible matter the problem of demarcation between science and non-science is not always relevant because all the variants existing today have adjustable parameters which can be always modified to fit the experimental data. In this regard there are some hopes that the new Large Hadron Collider (LHC) at CERN located in Switzerland and France and put into effect in 2008 will provide certain chances to test the string and loop quantum gravity theories as well as to detect the Higgs particles in order to broaden our knowledge about the real matter and eventually the Universe. The significance and importance of this subject for a mankind is again confirmed by awarding the Nobel prize in physics in 2008 to U.S. citizen Yoichiro Nambu and Japanese researchers Makoto Kobayashi and Toshihide Maskawa for their studies and work on “spontaneous broken symmetry” in subatomic physics.

The cosmic triangle as a daring premise is introduced in cosmology as a way of representing the past, present and future status of the God’s unique and most successful and complex creation called the Universe. Albert Einstein said “ Imagination is more important than knowledge. For knowledge is limited, whereas imagination embraces the entire world, stimulating progress, giving birth to evolution… Science without religion is lame, religion without science is blind”. For most of human history we have been in a quest for our true place in the cosmos. Who and what are we? Eventually we come to a conclusion that we inhabit an insignificant planet of an average-sized star totally lost in a galaxy tucked away in some forgotten corner of the Universe in which there are far more galaxies than people. This perspective is a courageous but rather perplexing continuation of our penchant for constructing and testing mental models of the skies; the Sun as a red-hot stone, the stars as a celestial flame and the Galaxy as the backbone of eternal night.