Sunday, October 09, 2011
Nobel Prize tied to cosmic acceleration, dark energy and dark matter in the Universe
Americans Saul Perlmutter, Adam Reiss, and Brian Schmitt have won the 2011 Nobel Prize in physics based upon their nearly 20-years of research on the expansion of the Universe.
Since 1929, scientists have known that the universe was expanding, because of the "Big Bang" nearly 14 billion years ago. Over the years since, astronomers have thought that the expansion of the universe was slowing because of gravity. Throughout most of the 20th century, the scientific community seemed to reconfirm the theory that the expansion of the universe was indeed slowing.
Beginning late in the 20th century, the three cited astrophysicists were skeptical and they spent years working with data collected from the Hubble Space Telescope about exploding stars to develop a new theory on dark energy and gravity to address how the expansion of the universe is actually accelerating, rather than decelerating. The physicists looking at extremely distant supernovae noticed something quite surprising: the supernovae were moving outward and accelerating.
The observation of cosmic acceleration has led to the theory that some mysterious, gravitationally repulsive dark energy must be behind the rising expansion of the cosmos - although we do not have the foggiest idea of what it is. Dark energy is one of the most pressing problems in astrophysics today [CNN] in that it permeates the cosmos at the rate of the accelerating expansion of the universe. A fabric of energy is expanding at an accelerating pace in every direction through space.
The only thing known or mathematically inferred is the existence of dark energy. The base inference is by how it influences the expansion of the universe. One explanation for dark energy is that it is a property of space. Albert Einstein was the first person to realize that "empty space is not nothing" - at the risk of a double negative expression. Space has amazing properties, many of which we are just beginning to understand after 50-years of human expansion only a mere 250,000 miles into it.
The first property that Einstein discovered is that it is possible for more space to come into existence. Then one version of Einstein's gravity theory, the version that contains a cosmological constant, makes a second prediction: "empty space" can possess its own energy.
Another explanation as to how space acquires or creates energy comes from quantum theory. In this theory, "empty space" is actually full of "virtual" particles that continually form and then disappear. Physicists have tried to calculate how much energy there is in empty space. No one has yet mathematically explained dark energy successfully. The mystery of how much energy there may be in empty space remains a mystery.
An alternative explanation for dark energy is that it is a new kind of dynamic energy field or fluid. It is thought to be something that fills all of space but whose effect on the expansion of the Universe is the opposite of matter. Scientists have no clue what this something is like or how or with what it interacts. Again, the dark energy mystery story continues.
Perhaps another alternative is that Einstein's theory of gravity is in error. If it were not correct, then a new theory of gravity is in need with no physics theory existing to replace it. If the theory of gravity is wrong, then humanity has lost the explanation of the motion of bodies in our known solar system. While there are alternative theories, none is compelling.
The efforts of the three 2011 Nobel Prize in physics winners are compelling to the European Space Agency. Euclid is in planning for 2019 with the purpose of launching a new space telescope to chart the 3-dimensional structure of the universe through the last 10 billion years, tracing expansion and the effects of dark energy on its evolution. Europeans are acting on American dark energy science.