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The light did not appear unlimited after the Big Bang. Here we see the phases after the big explosion (top left), about 13.8 billion years ago, to this day (lower right). S | Credit: Mark Garlik/Science Photo Library through Getty Images
Nowadays, the dark of the night is crossed with the light of the stars. But before the stars are born, does the light shine at the beginning of the universe?
The short answer is no. But the long answer reveals the exceptional Light trip. In the beginning, the light of the early universe was “trapped” and took several hundred thousand years to escape. It then took about 100 million years to form stars.
By examining the speed and direction in which the galaxies were moving, astronomer Edwin Hubble discovered The universe was expanding. This discovery of 1929 suggests that space was once smaller, and in the end scientists estimate that the whole universe was concentrated in one, infinitely dense point about 13.8 billion years ago, while to The The Big explosion happened.
“With the big blast, the space was created and expanded, along with everything in the universe,” Andrew LidenChairman of Physics and Astronomy at Bowling Green State in Ohio, Live Science told.
The only way the question that now represents the universe can fit in a small place is if at that time it was energy, “Laiden said. Einstein’s famous equation E = mc2 He revealed that energy and mass can be interchangeable, Layden explained.
As Universe Extended, its energy density decreases and cools. The first particles then began to form within the first second after the big explosion, According to Las Cumbres ObservatoryS They include photons that make up light as well as the protons, neutrons and electrons that make up atomsS About three minutes after the big explosion, protons and neutrons can merge together to create nuclei atoms like helium, according to NASAS
“Think of fog and dew,” Lyden said. “The high -energy particles are spread like water in fog and when the energy is low enough, they can be condensed as dew droplets.”
Related: Can something travel faster than the speed of light?
However, although the photons of light existed from the first second after the Big Bang, they still could not shine in the universe. This is because the early space was so hot that “electrons were moving too fast for Nuclear nuclei Keep them in orbit around them, ”Lyden said. “The universe was exactly this very hot, thick soup.
All the electrons that are freely in the early universe meant that light could not move much. “While the light tried to travel in a straight line during this time, she always bumped into electrons, so she couldn’t go very far,” Layden said.
Visual time line of space events after the Big Bang. | Credit: JPL/NASA
A similar situation is found in the sun, RaghunatanA cosmologist at the University of Illinois, Urbana-Champage, told Live Science. “You can imagine a photon of light created by nuclear reactions in the center of the sun, trying to come to the surface of the sun,” he said. “The center of the sun is extremely hot and therefore there are many free electrons. This means that light cannot travel on straight lines.”
The distance from the center of the sun to its surface is about 432 450 miles (696,000 kilometers). The speed of light in the vacuum is about 186,000 miles per second (300,000 km/sec), but in the sun, it takes about 1 million to 2 million years to escape from the light from the center of the sun to its surface, “Raghunatan said.
However, about 380,000 years after the Big Bang, the expansion of the universe leaves space to cool enough for the nuclear nuclei to fine on electrons. “When that happens, all these electrons are no longer free,” Lyden said. “This happens at about 3000 Kelvin [4,940 degrees Fahrenheit, or 2,725 degrees Celsius]The surface temperature of a cool reddish star. “
Within short years, “everything goes from hot dense soup to a clear universe where light can travel freely,” Lyden said. “At this point, the first photons in the universe can escape.”
The light typical of the universe when it was about 3000 kelvin was nearbyinfrared yes Visible wavelengthsLayden noted. However, as space has expanded for more than 13 billion years and cools to an average temperature of about 2.73 Kelvin (minus 455 F or minus 270 C), the first light of the universe extends to longer microwave wavelengths.
Astronomers first discovered this residual radiation from the Big Bang called a space microwave background, in 1964S
Linked mysteries
– What is the smallest particle in the universe? (What about the biggest?)
“What would happen if the speed of light was much shorter?”
– Where do electrons get energy to rotate around the nucleus of the atom?
The analysis of these microwaves gave a lot of insights. For example, gravitational pulling of galaxies can distort light – a phenomenon called gravitational lens. Considering the amount of distortion that the space microwave has experienced at different points in the sky can help scientists reconstruct the large-scale structure of the universe-galaxies and giant gaps between them through space, Ragunathan said.
After the release of light from the Big Bang, the universe experienced a period known as cosmic dark centuries. After all, after millions of years, gravitational pulling of clouds of gas made these lumps of matter collapse on themselves.
“This created the first generation of stars, and the universe had galaxies filled with stars about 1 billion years after the Big Bang, starting the space dawn,” Lyden said.