What is dark energy?
Dark energy is the name given to an unexplained force that is drawing galaxies away from each other, against the pull of gravity, at an accelerated pace. Dark energy is a bit like anti-gravity. Where gravity pulls things together at the more local level, dark energy tugs them apart on the grander scale. Its existence isn’t proven, but dark energy is many scientists’ best guess to explain the confusing observation that the universe’s expansion is speeding up. Experts still don’t know what’s driving this force, but the quest to learn more about dark energy is one of cosmologists’ top priorities. Confounding expectations The story of how dark energy was discovered is a classic case of science confounding expectations. In the mid-1990s, astronomers set out to measure how fast the universe was expanding. Because gravity draws mass together, most experts expected to find that gravity had slowed down the universe’s rate of ballooning, or perhaps that the rate was staying about the same. Inste
Dark Energy was found lately as a force which began to accelerate the Universe’s expansion 7 billion years ago. Its nature is still unknown but it might that such a force be an anti-gravitational force. It is still badly known weather this force is constant, leading to an ever expanding Universe or whether it is increasing, leading everything in the Universe to be eventually torn down, down to the atoms, 30 billion years from now.
Currently fashionable presentations of Dark Energy routinely begin with questions such as “how can we solve the mystery of Dark Energy?” One is seldom told why or how is Dark Energy a mystery, and is never really told what Dark Energy is. There are very good reasons for this. The long and short of it is that Dark Energy – as conceived by our modern physicists – is a fanciful notion that would bring a Mona Lisa smile even to Einstein’s lips. There is no proof that it exists, but it must exist, solely because it is universally agreed that: 1) the universe had a beginning; 2) the universe is expanding; 3) the known mass-energy of the universe cannot account for the supposed rate of expansion. Add to this that, somehow, by more recent so-called computations, this rate of expansion is accelerating, and one obtains all the ingredients for a modern scientific religion – a metaphysics of physics. Note that all of these requirements were Einstein’s legacy (for all that he would have smiled!); b
BERKELEY, CA When SCP researchers initially set out to measure the expansion rate of the universe, they expected to find that distant supernovae appeared brighter than their redshifts would suggest, indicating a slowing rate of expansion. Instead they found the opposite: at a given redshift, distant supernovae were dimmer than expected. Expansion was accelerating. Not only did this discovery mean that the universe would never come to an end, more fundamentally it implied that a large part of the universe is made of something we know nothing about — the mysterious whatever-it-is that goes by the name “dark energy.
Well, the simple answer is that we don’t know. It seems to contradict many of our understandings about the way the universe works. We all know that light waves, also called radiation, carry energy. You feel that energy the moment you step outside on a hot summer day. Einstein’s famous equation, E = mc2, teaches us that matter and energy are interchangeable, merely different forms of the same thing. We have a giant example of that in our sky: the Sun. The Sun is powered by the conversion of mass to energy.
