Did you know that the universe is expanding? What is making it expand? Actually, our universe has always been expanding, with all galaxies receding from each other, except for those bound in clusters. However, scientists have observed there has been a change of pace and that acceleration is occurring. As ordinary people, we may observe these changes in that it truly feels these days that time is going faster than it did before.
Astronomers were stunned to discover in 1998 while trying to measure the distance of from a supernova to the earth, that the distance was further than they had expected.
Evidence suggesting that the universe is in the grasp of dark energy, a puzzling antigravity force that is causing it to expand at an ever-accelerating rate. The universe’s expansion was one of the biggest discoveries of the 20th century.
Cosmologists–scientists who ponder the origins of the universe–had thought that the expansion either was constant– gradually spreading but basically staying the same–or that it was slowing.
If gravity were causing the universe to slow, then it would eventually collapse on itself, ending up in what has been called the Big Crunch. This would be the opposite of the Big Bang theory that the universe came into existence in a gigantic explosion 10 billion to 15 billion years ago.
An accelerating universe, on the other hand, would mean all stars, galaxies and other matter would spread apart so fast and become so diluted that over billions of years the universe would be nothing but a void.
What it comes down to is that scientists know very little about gravity. It used to be clear that gravity was an attraction between bodies, and on Earth that meant things always fell down.
But cosmologists now suspect that on the scale of the universe, gravity, propelled by something they call dark energy, behaves just the opposite. Newton would have been shocked to see an apple fall up.
“We do have antigravity now, but only on this enormous scale,” said Bruce Winstein, director of the U. of C.’s Center for Cosmological Studies, where the dark energy telescope was conceived and developed.
One of the most bizarre features is that as the universe expands, it creates more dark energy that pushes the expansion to warp speeds.
“If dark energy really is 70 percent of the whole universe and it behaves the way current theory predicts, then it really is beginning to dominate everything about the universe,” said Tony Stark of the Harvard-Smithsonian Center for Astrophysics “It will actually turn off the formation of galaxies. From now on there will be very many fewer galaxy clusters formed.”
.Theory predicts that if dark energy is greatly accelerating the universe’s expansion, then galaxies will be scattered too far apart to form many clusters. The fewer the clusters, the more powerful the dark energy.
Dark energy is different from another cosmological mystery, dark matter. Dark matter refers to the unseen matter that exerts enough gravity to keep spinning galaxies from flying apart. Scientists are confident they eventually will solve the mystery of dark matter, which is probably tiny ubiquitous particles that have not yet been detected.
Because matter and energy are interchangeable, an observation made by Albert Einstein, it has been estimated that dark matter makes up about 20 percent to 25 percent of the universe’s energy and that stars, planets, and people make up a mere 3 percent to 5 percent.
The giant’s share, 70 percent, is now believed to be the mysterious dark energy.
The nice thing is, more data will solve this mystery. In an upcoming Dark Energy Spectroscopic Instrument (DESI) survey aims to begin creating a 3D cosmic map in 2018.
The cosmos is a never-ending-story of mystery and wonder created for humankind to treasure, enjoy and protect.