# How do we determine the production of H and He during BBN?

• pianoplayer98
In summary, the production of H and He during Big Bang Nucleosynthesis (BBN) is determined through a combination of theoretical models and observations. Several factors, such as the density and expansion rate of the universe, can affect this production. The accuracy of the observed abundance of H and He is confirmed through comparisons with BBN models and measurements of cosmic microwave background radiation and light emitted by distant objects. While it is not possible to simulate BBN in a laboratory, the production of H and He strongly supports the Big Bang theory due to the close match between predicted and observed abundances and the consistent temperatures and energies required.
pianoplayer98
How do we calculate how much H and He is created during Big Bang Nucleosynthesis?

Wikipedia states that regardless of some initial conditions during BBN, it will always be that 74% of the universe is H and 24% of the universe is He, plus or minus a couple percent. How is this determined?

Sorry - I know this question is fairly basic.

I don't think there is an analytic approach, but you can simulate the conditions after the big bang numerically with different parameters. With known cross-sections for the different processes at different energies, you can simulate nucleosynthesis.

## 1. How is the production of H and He during Big Bang Nucleosynthesis (BBN) determined?

The production of H and He during BBN is determined through a combination of theoretical models and observations. Scientists use mathematical equations and simulations to predict the amount of H and He that should be produced during the early universe, and then compare these predictions to observations of the abundance of these elements in the universe today.

## 2. What factors affect the production of H and He during BBN?

Several factors can affect the production of H and He during BBN. These include the density and expansion rate of the universe, the amount of matter and radiation present, and the temperature and energy of the particles during BBN. Small variations in these factors can lead to significant differences in the amount of H and He produced.

## 3. How do we know that the observed abundance of H and He is accurate?

Scientists can determine the abundance of H and He in the universe through observations of cosmic microwave background radiation and the light emitted by distant stars and galaxies. These measurements are then compared to the predictions of BBN models, which have been shown to accurately match the observed abundance of H and He.

## 4. Can the production of H and He during BBN be simulated in a laboratory?

It is not currently possible to simulate the conditions of BBN in a laboratory setting. The extremely high temperatures, densities, and energies required to create the same conditions as the early universe are beyond our current technological capabilities. Instead, scientists rely on theoretical models and observations to understand the production of H and He during BBN.

## 5. How does the production of H and He during BBN support the Big Bang theory?

The production of H and He during BBN is a key piece of evidence that supports the Big Bang theory. The predicted and observed abundances of these elements match closely, providing strong evidence for the theory. Additionally, the temperature and energy required for the production of these elements is consistent with the high temperatures and densities of the early universe predicted by the Big Bang theory.

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