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Here are five great mysteries that have yet to be solved. These questions concern the basic structure of reality and its processes and have left scientists scratching their heads for years.
1. What is mass? Mass is in every substance and the source of weight and inertia. We know mass from the scale, the gym and the bus. At zero gravity, mass has inertia, not weight. We know enough about mass to predict a solar eclipse or send a probe to Jupiter.
Clues about the source of mass led to a property of mass known as inertia. Einstein's first draft of the theory of General Relativity was titled, "Does the Inertia of a Body Depend on Its Energy Content?" Einstein's equation E=mc2 (originally m=E/c2) answers "yes" to that question.
Clearly, he was onto something, but what? Frank Wilczek, 2004 Nobel Prize winner and professor of physics at the Massachutsetts Institute of Technology, explains in his paper, The Origins of Mass, that we know we can create mass from energy, but that still doesn't identify its origin.
Currently, there is a race among particle accelerator facilities to find the particle believed to be the most likely source of mass: The Higgs Boson. The Tevatron collider at Fermilab in Chicago and the Large Hadron Collider (LHC) near Geneva, Switzerland have both been searching for the Higgs Boson for many years now. Recent experiments at the LHC offer a strong suggestion that the Higgs Boson will not be found in the middle of the range of energies posulated by the Standard Model. It also happens to be the only particle anticipated by the Standard Model of particle physics, but not yet observed.
2. What happens to mass in a black hole? A black hole is the remains of a collapsed star so dense that not even light can escape. Picture the mass of our sun in a ball about 10 miles across and you get the idea. So what happens to mass in a black hole? We know that mass goes in, and that's it.
One theory to answer the question is the Black Hole Information Paradox. This theory suggests that information is not completely conserved and that it could disappear in a black hole, contrary to Quantum Mechanics, which holds that information, like energy, is conserved. In the same way that energy is neither created nor destroyed, information is conserved according to the same principles — it cannot simply disappear (though some who use computers may disgree). Still, no one is really sure where mass goes once it falls into a black hole.
3. Why does time go one way? Man has long since known about time and has sought ways to measure it. Man even built a clock that is off by only one second in 138 million years. But, only recently has man begun to look at the source and direction of time.
Scientists have learned that at microscopic scales and smaller, time has symmetry - that is, every observed process can be reversed if time went backwards. At the macroscopic level, our perception is that most processes are not reversible. After centuries of research, we still don't know where it comes from or why it goes only one way.
4. What is the source of gravity? Einstein's General Relativity theory is regarded as the most accurate theory of gravity. General Relativity holds that mass can cause space to warp. This warping of space by mass is what causes particles to accumulate together to form stars, planets, galaxies and even black holes. General Relativity says that matter and energy together cause space to warp around it.
The Higgs Boson, and the corresponding Higgs Field, are offered as a source of gravity. The Higgs Field is postulated as the field which gives everything mass. Ironically, the Higgs Boson is also classified as a Weakly Interacting Massive Particle (WIMP). As noted previously, however, the Higgs Boson has not yet been detected, but the hunt is still on, and quite active, too.
The scientific community has considered many competing theories, but so far none are as good at describing experimental observations of gravity as General Relativity.
5. How does quantum entanglement work? It has been observed that "entangled" particles will be in complementary states when measured (i.e., top or bottom spin). Moreover, it also has been observed that when the state of one particle is changed and measured, the state of the other particle in the pair is also changed instantaneously, regardless of the distance involved. Einstein referred to this behavior as "spooky action" at a distance.
While no one can really explain this behavior, it is being very actively researched for use in computing and communication. For example, a team led by John Martinis at the University of California, Santa Barbara has demonstrated quantum entanglement at the macroscopic scale by entangling two superconductors each about a milimeter across. Measurements of the direction of current in one strip was the opposite of the direction of current in the other strip when entangelment was achieved.
Quantum entanglement is a prominent part of quantum mechanics, and it has theoretical and practical applications. For example, quantum mechanics is used to design the chips that run our computers today.
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Scott Dunn is an IT professional, teacher and writer living in Salt Lake City. He is also a passionate Linux enthusiast.
