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zaman786
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- how do we calculated the number of atoms at the start , after big bang?
hi, how do we calculated the number of atoms at the start of universe i.e, after big bang?
Technically, atoms couldn't form and remain stable until the recombination epoch, about 380,000 years after the Big Bang. Some of the best evidence for the Big Bang theory itself, comes from the analysis of the expected proportion of light elements during this initial phase of nucleosynthesis.zaman786 said:TL;DR Summary: how do we calculated the number of atoms at the start , after big bang?
hi, how do we calculated the number of atoms at the start of universe i.e, after big bang?
Wikipedia says 0.25 per cubic meter in the observable universe.Vanadium 50 said:Are you sure?
Their references areIn the observable universe, atoms have an average density of 0.25 atoms/m³. According to the Big Bang model (Lambda-CDM model), they make up around 4.9 percent of the total energy density. The remaining 95.1 percent, whose nature is still largely unclear, is composed of about 27 percent dark matter and 68 percent dark energy, as well as small contributions from neutrinos and electromagnetic radiation.
The estimated number of atoms in the observable universe is around 10^80. This estimate is based on calculations that take into account the average density of matter in the universe and the volume of the observable universe.
The observable universe refers to the part of the universe that we can see from Earth with the available technology, which includes all light and other signals received from any object farther than approximately 13.8 billion light-years away. This boundary is due to the finite speed of light and the age of the universe.
The total number of atoms in the universe can change over time due to processes such as nuclear fusion in stars, where lighter atoms combine to form heavier elements, and other nuclear reactions in various astronomical events that can lead to matter being converted to energy and vice versa.
Scientists estimate the number of atoms by using astronomical observations to calculate the mass of galaxies and other large-scale structures. They then estimate the proportion of that mass that is ordinary matter (as opposed to dark matter and dark energy) and use assumptions about the composition of this matter to estimate the number of atoms.
Understanding the number of atoms in the universe helps astronomers and physicists to better understand the composition and evolution of the cosmos, including the processes that govern star and galaxy formation, the distribution of matter and energy in the universe, and the overall dynamics and fate of the universe.