As far as humans can tell, space is infinite; it has no end or borders. Scientists believe that space will always seem infinite to humans for two reasons. First, our investigation of space has never found an edge (or any indications of an edge). Second, measurements show that space is expanding faster and faster, which pushes the edges of the universe ? if there are any ? ever farther out.Know More
Space is continuing to expand (meaning that all the galaxies are speeding away from the center of the universe) because of the Big Bang's momentum and because of a substance called dark energy. Dark energy occupies the seemingly empty parts of the universe, but it has a strong negative pressure, pushing things away from each other even faster than they would move as a result of the Big Bang. This makes it difficult for humans to measure the farthest reaches of space.
In addition, anything traveling through space ? including humans' investigative tools, techniques and measurements ? is limited to the fastest possible speed: the speed of light. Because nothing can travel faster than light, there is a limit to how far scientists can explore or understand the universe. The size of the observable universe (the part astronomers could potentially study) is approximately 45.7 billion light-years across.Learn more about Universe
Although the ultimate fate of the universe is a largely debated topic, according to the University of Tennessee, in an open universe the universe will continue to expand forever. This is due to insufficient mass to cause the expansion to stop.Full Answer >
In 1922, Russian mathematician Alexander Friedmann answered Albert Einstein's equations of general relativity. Friedmann's answers led to the theory that the universe is dynamic, meaning that it changes in size over time. Friedmann introduced the term "expanding universe" into the scientific lexicon.Full Answer >
The solar plexus, or celiac plexus, is a large cluster of nerves that relay messages from the major organs of the abdomen to the brain. These organs, called visceral organs, are important to metabolism and to general life functioning. The solar plexus monitors them and makes sure they are functioning correctly.Full Answer >
Sound is unable to travel through truly empty space. The phenomenon known as sound is the perception of alternating waves of compression passing through a medium. Unlike light, which is able to propagate without a medium, sound waves must have a medium, such as air, water or rock, to carry them.Full Answer >