DARK THE FORCE TEARING SPACE APART ENERGY

It's the most mystifying phenomenon in the universe, but we're hot on its trail

- Kulvinder Singh Chadha

Our universe is growing. Ever since the Big Bang, every point in the fabric of space has been expanding in all directions. This expansion is carrying almost all galaxies away from us. The biggest surprise came in 1998 with the discovery that not only is the universe expanding, but that expansion is accelerating. Nobody knows why, but scientists have come up with a term for the mysterious force driving the acceleration: dark energy.

According to data from the European Space Agency's (ESA) Planck spacecraft, dark energy constitutes over two-thirds of all the mass and energy in the universe, or 68.3 percent. The remainder is 26.8 percent dark matter and just 4.9 percent normal matter, which makes up the stars, galaxies, and planets. Scientists are perplexed as to what dark energy is. There are ideas, but nothing concrete. It's important to try and figure out the puzzle of dark energy because the fate of the universe depends on it. Prior to the discovery of dark energy, cosmologists had expected to find that the expansion of the universe was running out of steam 13.8 billion years after the Big Bang. If that was the case, the universe could have gone in three directions depending upon how much matter, and therefore gravity, there was in the universe.

If there was enough matter, its gravity would act on the expanding universe, slowing the expansion and gradually overcoming it, eventually causing the universe to begin to shrink again before collapsing in a 'Big Crunch'. If the amount of matter and gravity were finely balanced with the energy of the expanding universe, it would create a static universe that would remain forever. However, if there was not enough matter in the universe to counteract the expansion, then the universe would continue to expand forever, taking all the galaxies with it until they disappeared over the cosmic horizon, leaving the Milky Way all alone.