Did light exist at the beginning of the universe?
Nowadays, the darkness of the night is interspersed with the light of the stars. But before the birth of the stars, did light shine at the start of the universe?
The short answer is “no”. But the long answer reveals the extraordinary trip of Light. At the beginning, the light of the early universe was “trapped” and it took several hundred thousand years to escape. Then it took about 100 million years for the stars to form.
By examining the speed and direction in which the galaxies moved, astronomer Edwin Hubble discovered The universe developed. This discovery of 1929 suggested that the cosmos was once smaller, scientists finally calculating that the whole universe was concentrated in an infinitely dense point about 13.8 billion years ago, until the Big Bang arrived.
“With Big Bang, space has been created and enlarged, as well as everything in the universe,” Andrew LaydenPresident of physics and astronomy at Bowling Green State University in Ohio, told Live Science.
The only way that all the question that now makes up the universe could hold in a small place “is if it was energy at that time,” said Layden. The famous Einstein equation E = MC2 revealed that energy and mass can be interchangeable, said Layden.
Like the universe Extended, the density of its energy has decreased and it has cooled. The first particles then began to train in the first second after the Big Bang, According to the Las Cumbre Observatory. These include photons which make up the light, as well as the protons, neutrons and electrons that make up atoms. About three minutes after Big Bang, protons and neutrons could merge to create atom nuclei such as helium, according to Nasa.
“Think of fog and dew,” said Layden. “The particles in a high energy state are dispersed like water in the fog, and when the energy becomes low enough, they can condense like dew drilters.”
In relation: Can something travel faster than the speed of light?
However, although photons of light existed since the first second after the Big Bang, they could not yet shine through the universe. It is because the first cosmos was so hot that “the electrons moved too quickly for atomic nuclei To hold them in orbit around them, “said Layden.” The universe was just this very hot and dense soup. “”
All the electrons that take place freely in the first universe meant that light could not move much. “While Light was trying to travel in a straight line during this period, he always hit the electrons, so that could not go very far,” said Layden.
A similar situation is in the sun, Srinivasan RaghunathanA cosmologist at the University of Illinois, Urbana-Champaign, told Live Science. “You can imagine a photon of light created by nuclear reactions in the center of the sun trying to go out on the surface of the sun,” he said. “The center of the sun is extremely hot, so there are many free electrons present. This means that the light cannot travel in a straight line.”
The distance between the center of the sun on its surface is around 432,450 miles (696,000 kilometers). The speed of light in the void is around 186,000 miles per second (300,000 km / s), but in the sun, “it takes about 1 to 2 million years so that the light escapes from the center of the sun to its surface,” said Raghunathan.
However, around 380,000 years after the Big Bang, the expansion of the universe has left the cosmos sufficiently cooled for the atomic nuclei to ice on the electrons. “When this happens, all of these electrons are no longer free,” said Layden. “This happens at around 3,000 Kelvin [4,940 degrees Fahrenheit, or 2,725 degrees Celsius]The surface temperature of a fresh reddish star. “”
In a few years, “everything goes from a hot dense soup to a clear universe where light can travel freely,” said Layden. “At that time, the first photons of the universe can escape.”
The typical light of the universe when it was around 3,000 kelvins was nearinfrared has Visible wavelengthsNoted Layden. However, as the cosmos developed in more than 13 billion years and has cooled at an average temperature of around 2.73 Kelvin (minus 455 F, or less 270 C), the first light in the universe was stretched at longer microwave wave waves.
Astronomers first detected this remaining radiation of the Big Bang, called the Cosmic microwave background, in 1964.
The analysis of these microwaves has given a lot of information. For example, the gravitational attraction of galaxies can distort light – a phenomenon called gravitational lens. Examining the quantity of distortion that the cosmic microwave history experienced at different times in the sky can help scientists rebuild the large -scale structure of the universe – the layout of galaxies and giant giants through the cosmos, said Raghunathan.
After the release of Big Bang light, the universe experienced a period known as Cosmic Dark Ages. Finally, after millions of years, the gravitational attraction of gas clouds led these piles of material to collapse on themselves.
“It created the first generation of stars, and the universe had galaxies full of stars of around 1 billion years after the Big Bang, starting cosmic dawn,” said Layden.
Sun Quiz: Do you know our house star well?
