Facts on Universe

 About Universe

The universe is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and energy. The earliest cosmological models of the universe were developed by ancient Greek and Indian philosophers and were geocentric, placing Earth at the center. Over the centuries, more precise astronomical observations led Nicolaus Copernicus to develop the heliocentric model with the Sun at the center of the Solar System. The Big Bang theory is the prevailing cosmological description of the development of the universe. According to estimation of this theory, space and time emerged together 13.799±0.021 billion years ago and the energy and matter initially present have become less dense as the universe expanded.

Here's a video that would bring out a clear understanding of the universe. 

FACTS    

The Universe Is Getting Bigger

In the 1920s, astronomer Edwin Hubble made the revolutionary discovery that the universe is not static, but rather is expanding. But, it was long thought that the gravity of matter in the universe would slow this expansion or even cause it to contract.

In 1998, the Hubble Space Telescope studied very distant supernovas and found that, a long time ago, the universe was expanding more slowly than it is today. This puzzling discovery suggested that an inexplicable force, called dark energy, is driving the accelerating expansion of the universe. [Full Story]

While dark energy is thought to be the strange force that is pulling the cosmos apart at ever-increasing speeds, it remains one of the greatest mysteries in science because its detection remains elusive to scientists.

The Universe's Growth Spurt Is Accelerating

The universe's acceleration also confirms Albert Einstein's theory of general relativity, and lately, scientists have revived Einstein's cosmological constant to explain the strange dark energy that seems to be counteracting gravity and causing the universe to expand at an accelerating pace. [Full Story]

Three scientists won the 2011 Nobel Prize in Physics for their 1998 discovery that the expansion of the universe was accelerating. [Full Story]

The Universe Could Be Flat

The shape of the universe is influenced by the struggle between the pull of gravity (based on the density of the matter in the universe) and the rate of expansion. If the density of the universe exceeds a certain critical value, then the universe is "closed," like the surface of a sphere. This implies that the universe is not infinite but has no end. In this case, the universe will eventually stop expanding and start collapsing in on itself, in an event known as the "Big Crunch."

If the density of the universe is less than the critical density value, then the shape of the universe is "open," like the surface of a saddle. In this case, the universe has no bounds and will continue to expand forever. [Full Story]

Yet, if the density of the universe is exactly equal to the critical density, then the geometry of the universe is "flat," like a sheet of paper. Here, the universe has no bounds and will expand forever, but the rate of expansion will gradually approach zero after an infinite amount of time. Recent measurements suggest that the universe is flat with roughly a 2 percent margin of error.

The Universe Is Filled With Invisible Stuff

The universe is overwhelmingly made up of things that cannot be seen. In fact, the stars, planets and galaxies that can be detected make up only 4 percent of the universe, according to astronomers. The other 96 percent is made up of substances that cannot be seen or easily comprehended.

These elusive substances, called dark energy and dark matter, have not been detected, but astronomers base their existence on the gravitational influence that both exert on normal matter, the parts of the universe that can be seen. [Full Story]

The Universe Has Echoes of Its Birth

The cosmic microwave background is made up of light echoes left over from the Big Bang that created the universe 13.7 billion years ago. This relic of the Big Bang explosion hangs around the universe as a pocked veil of radiation.

The European Space Agency's Planck mission mapped the entire sky in microwave light to reveal new clues about how the universe began. Planck's observations are the most precise views of the cosmic microwave background ever obtained. Scientists are hoping to use data from the mission to settle some of the most debated questions in cosmology, such as what happened immediately after the universe was formed. [Full Story]

There May Be More Universes

The idea that we live in a multiverse, in which our universe is one of many, comes from a theory called eternal inflation, which suggests that shortly after the Big Bang, space-time expanded at different rates in different places. According to the theory, this gave rise to bubble universes that could function with their own separate laws of physics.

The concept is controversial and had been purely hypothetical until recent studies searched for physical markers of the multiverse theory in the cosmic microwave background, which is a relic of the Big Bang that pervades our universe. [Full Story]

Researchers searched the best available observations of the cosmic microwave background for signs of bubble universe collisions, but didn't find anything conclusive. If two universes had collided, the researchers say, it would have left a circular pattern behind in the cosmic microwave background.