Formation of the universe
The universe was born with the Big Bang as an unimaginably hot, dense point. When the universe was just 10-34 of a second or so old — that is, a hundredth of a billionth of a trillionth of a trillionth of a second in age — it experienced an incredible burst of expansion known as inflation, in which space itself expanded faster than the speed of light. During this period, the universe doubled in size at least 90 times, going from subatomic-sized to golf-ball-sized almost instantaneously.
Most astronomers believe the Universe began in a Big Bang about 14 billion years ago. At that time, the entire Universe was inside a bubble that was thousands of times smaller than a pinhead. It was hotter and denser than anything we can imagine.
Then it suddenly exploded. The Universe that we know was born. Time, space and matter all began with the Big Bang. In a fraction of a second, the Universe grew from smaller than a single atom to bigger than a galaxy. And it kept on growing at a fantastic rate. It is still expanding today.
As the Universe expanded and cooled, energy changed into particles of matter and antimatter. These two opposite types of particles largely destroyed each other. But some matter survived. More stable particles called protons and neutrons started to form when the Universe was one second old.
Over the next three minutes, the temperature dropped below 1 billion degrees Celsius. It was now cool enough for the protons and neutrons to come together, forming hydrogen and helium nuclei.
After 300 000 years, the Universe had cooled to about 3000 degrees. Atomic nuclei could finally capture electrons to form atoms. The Universe filled with clouds of hydrogen and helium gas.
The Big Bang did not occur as an explosion in the usual way one think about such things, despite one might gather from its name. The universe did not expand into space, as space did not exist before the universe, according to NASA Instead, it is better to think of the Big Bang as the simultaneous appearance of space everywhere in the universe. The universe has not expanded from any one spot since the Big Bang — rather, space itself has been stretching, and carrying matter with it.
Since the universe by its definition encompasses all of space and time as we know it, NASA says it is beyond the model of the Big Bang to say what the universe is expanding into or what gave rise to the Big Bang. Although there are models that speculate about these questions, none of them have made realistically testable predictions as of yet.
In 2014, scientists from the Harvard-Smithsonian Center for Astrophysics announced that they had found a faint signal in the cosmic microwave background that could be the first direct evidence of gravitational waves, themselves considered a "smoking gun" for the Big Bang. The findings werehotly debated, but the search for these mysterious ripples continues.
The first scientist to come up with the idea of a 'big bang' was the astrophysicist Friedrich Franz Friedmann who used relativity field equations to prove that the universe is expanding. Edwin Hubble's observations later proved this theory. Hubble discovered the red shift of galaxies. He measured their distances from Earth by observing variable stars called Cepheids. The red shift distance law of galaxies is now referred to as Hubble's Law.
The discovery of cosmic microwave background radiation in 1965 made the Big Bang theory the best theory of the origin and evolution of the universe. Radio astronomers Arno Penzias and Robert Wilson discovered the cosmic microwave (high frequency radio wave) background which is thought to be leftover radiation from the initial explosion of matter - the 'Big Bang'.
Apparently this theory was called 'The big bang' by a radio commentator who was mocking it. Initially the theory was called 'The primeval atom'. Today astrophysicists with a sense of humour sum up the Big Bang theory as the following: First there was nothing, then there was the bang and then there was everything. See image 1.
The formation of the solar systemAccording to the Big Bang theory, the solar system was formed from a cloud of space dust and gas that was 'squeezed' by a supernova explosion. As the nebula contracted, it spun increasingly rapidly, leading to frequent collisions between dust grains. Gravity pulled the gas and dust together, forming a solar nebula. This solar nebula grew hotter and denser, forming a disk of gas and dust in its centre. Particles of nebula dust started to stick together, forming clumps that eventually formed planets and their satellites. Eventually the hot centre of the solar nebula formed a star - the sun. Different planetary particles left over from this initial explosion can still be found flying around in space. These particles are called meteorites. By studying these meteorites,scientists have found that our solar system is about 4 600 million years old
Most astronomers believe the Universe began in a Big Bang about 14 billion years ago. At that time, the entire Universe was inside a bubble that was thousands of times smaller than a pinhead. It was hotter and denser than anything we can imagine.
Then it suddenly exploded. The Universe that we know was born. Time, space and matter all began with the Big Bang. In a fraction of a second, the Universe grew from smaller than a single atom to bigger than a galaxy. And it kept on growing at a fantastic rate. It is still expanding today.
As the Universe expanded and cooled, energy changed into particles of matter and antimatter. These two opposite types of particles largely destroyed each other. But some matter survived. More stable particles called protons and neutrons started to form when the Universe was one second old.
Over the next three minutes, the temperature dropped below 1 billion degrees Celsius. It was now cool enough for the protons and neutrons to come together, forming hydrogen and helium nuclei.
After 300 000 years, the Universe had cooled to about 3000 degrees. Atomic nuclei could finally capture electrons to form atoms. The Universe filled with clouds of hydrogen and helium gas.
The Big Bang did not occur as an explosion in the usual way one think about such things, despite one might gather from its name. The universe did not expand into space, as space did not exist before the universe, according to NASA Instead, it is better to think of the Big Bang as the simultaneous appearance of space everywhere in the universe. The universe has not expanded from any one spot since the Big Bang — rather, space itself has been stretching, and carrying matter with it.
Since the universe by its definition encompasses all of space and time as we know it, NASA says it is beyond the model of the Big Bang to say what the universe is expanding into or what gave rise to the Big Bang. Although there are models that speculate about these questions, none of them have made realistically testable predictions as of yet.
In 2014, scientists from the Harvard-Smithsonian Center for Astrophysics announced that they had found a faint signal in the cosmic microwave background that could be the first direct evidence of gravitational waves, themselves considered a "smoking gun" for the Big Bang. The findings werehotly debated, but the search for these mysterious ripples continues.
The first scientist to come up with the idea of a 'big bang' was the astrophysicist Friedrich Franz Friedmann who used relativity field equations to prove that the universe is expanding. Edwin Hubble's observations later proved this theory. Hubble discovered the red shift of galaxies. He measured their distances from Earth by observing variable stars called Cepheids. The red shift distance law of galaxies is now referred to as Hubble's Law.
The discovery of cosmic microwave background radiation in 1965 made the Big Bang theory the best theory of the origin and evolution of the universe. Radio astronomers Arno Penzias and Robert Wilson discovered the cosmic microwave (high frequency radio wave) background which is thought to be leftover radiation from the initial explosion of matter - the 'Big Bang'.
Apparently this theory was called 'The big bang' by a radio commentator who was mocking it. Initially the theory was called 'The primeval atom'. Today astrophysicists with a sense of humour sum up the Big Bang theory as the following: First there was nothing, then there was the bang and then there was everything. See image 1.
The formation of the solar systemAccording to the Big Bang theory, the solar system was formed from a cloud of space dust and gas that was 'squeezed' by a supernova explosion. As the nebula contracted, it spun increasingly rapidly, leading to frequent collisions between dust grains. Gravity pulled the gas and dust together, forming a solar nebula. This solar nebula grew hotter and denser, forming a disk of gas and dust in its centre. Particles of nebula dust started to stick together, forming clumps that eventually formed planets and their satellites. Eventually the hot centre of the solar nebula formed a star - the sun. Different planetary particles left over from this initial explosion can still be found flying around in space. These particles are called meteorites. By studying these meteorites,scientists have found that our solar system is about 4 600 million years old