Dark Energy: The Biggest Mystery in the Universe

At the South Pole, astronomers try to unravel a force greater than gravity that will determine the fate of the cosmos!

Twice a day, seven days a week, from February to November for the past four years, two researchers have layered themselves with thermal underwear and outerwear, with fleece, flannel, double gloves, double socks, padded overalls and puffy red parkas, mummifying themselves until they look like twin Michelin Men. Then they step outside, trading the warmth and modern conveniences of a science station for a minus-100-degree Fahrenheit featureless landscape, flatter than Kansas and one of the coldest places on the planet. They trudge in darkness nearly a mile, across a plateau of snow and ice, until they discern, against the backdrop of more stars than any hands-in-pocket backyard observer has ever seen, the silhouette of the giant disk of the South Pole Telescope, where they join a global effort to solve possibly the greatest riddle in the universe: what most of it is made of?

For thousands of years our species has studied the night sky and wondered if anything else is out there. Last year we celebrated the 400th anniversary of Galileo’s answer: Yes. Galileo trained a new instrument, the telescope, on the heavens and saw objects that no other person had ever seen: hundreds of stars, mountains on the Moon, satellites of Jupiter. Since then we have found more than 400 planets around other stars, 100 billion stars in our galaxy, hundreds of billions of galaxies and never ending numbers beyond our own, even the faint radiation that is the echo of the Big Bang.

One thing was fairly certain about the expansion of the universe. It might have enough energy density to stop its expansion and re-collapse, it might have so little energy density that it would never stop expanding, but gravity was certain to slow the expansion as time went on. Granted, the slowing had not been observed, but, theoretically, the universe had to slow. The universe is full of matter and the attractive force of gravity pulls all matter together. Then came the Hubble Space Telescope’s observations of very distant supernovae that showed that, a long time ago, the universe was actually expanding more slowly than it is today. So the expansion of the universe has not been slowing due to gravity, as everyone thought, it has been accelerating. No one expected this, no one knew how to explain it. But something was causing it.

Astronomers have compiled evidence that what we’ve always thought of as the actual universe—me, you, this article, planets, stars, galaxies, all the matter in space—represents a mere 5% of what’s actually out there. The rest they call, for want of a better word, DARK: 27% is something they call dark matter, and 68% is something even more mysterious, which they call dark energy goes further and ranks dark energy as “the most profound mystery in all of science.” I think I would die of inquisitiveness.

Scientists have some ideas about what dark matter might be—exotic and still hypothetical particles—but they have hardly a clue about dark energy. “What Is the Nature of Dark Energy?” as one of the most pressing scientific problems of the coming decades. The effort to solve it has mobilized a generation of astronomers in a rethinking of physics and cosmology to rival and perhaps surpass the revolution of Galileo. They are coming to terms with a deep irony: it is sight itself that has blinded us to nearly the entire universe. And the recognition of this blindness, in turn, has inspired us to ask, as if for the first time: What is this cosmos we call home? Scientists reached a consensus that there was more to the universe than meets the eye. In computer simulations of our galaxy, the Milky Way, theorists found that the centre would not hold—based on what we can see of it, our galaxy doesn’t have enough mass to keep everything in place. As it rotates, it should disintegrate, shedding stars and gas in every direction. Either a spiral galaxy such as the Milky Way violates the laws of gravity, or the light emanating from it—from the vast glowing clouds of gas and the myriad stars—is an inaccurate indication of the galaxy’s mass.
But what if some portion of a galaxy’s mass didn’t radiate light? If spiral galaxies contained enough of such mystery mass, then they might well be obeying the laws of gravity. Astronomers dubbed the invisible mass “dark matter.” Nobody ever told us that all matter radiated,” The effort to understand dark matter defined much of astronomy for the next two decades. Astronomers may not know what dark matter is, but inferring its presence allowed them to pursue in a new way an eternal question: What is the fate of the universe?

They already knew that the universe is expanding. It was discovered that distant galaxies were moving away from us and that the farther away they got, the faster they seemed to be receding. And that might be the reason why we are still wandering among heavenly bodies of Milky way, although yeah! I agree Milky way is colossal, vast and bulky but what humanity is awaiting for greater accomplishment of being able to seek out of Milky way just the way aliens did from their galaxies, didn’t they?

This was a radical idea. Instead of the stately, eternally unchanging still life that the universe once appeared to be, it was actually alive in time, like a movie. Rewind the film of the expansion and the universe would eventually reach a state of infinite density and energy—what astronomers call the Big Bang. But what if you hit fast-forward? How would the story end?

The universe is full of matter, and matter attracts other matter through gravity. Astronomers reasoned that the mutual attraction among all that matter must be slowing down the expansion of the universe. But they didn’t know what the ultimate outcome would be. Would the gravitational effect be so forceful that the universe would ultimately stretch a certain distance, stop and reverse itself, like a ball tossed into the air? Or would it be so slight that the universe would escape its grasp and never stop expanding, like a rocket leaving Earth’s atmosphere? Or did we live in an exquisitely balanced universe, in which gravity ensures a Goldilocks rate of expansion neither too fast nor too slow—so the universe would eventually come to a virtual standstill?

This article would definitely put you off leaving your brain befuddled.