Hubble scale and energy density during inflation

In summary, the Hubble scale during inflation refers to the size of the observable universe during the period of rapid expansion known as inflation. It increases exponentially, contributing to the large-scale homogeneity and isotropy of the universe we observe today. The energy density during inflation is believed to be extremely high and drives the rapid expansion of the universe. As the universe expands, the energy density decreases, leading to a slowing down of the expansion rate. Evidence for the Hubble scale and energy density during inflation comes from observations of the cosmic microwave background radiation and the large-scale structure of the universe. These observations support the theory of inflation and provide evidence for its role in shaping the universe.
  • #1
spaghetti3451
1,344
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Is the energy density ##\rho## in the early universe and the Hubble scale ##H## during inflation related by the formula

$$H^{4} = \frac{9}{64\pi^{2}} \frac{\rho^{2}}{M_{P}^{4}}?$$

Here, ##M_{P}## is the Planck mass.

Can you suggest any resources where this is explained?
 
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  • #2
Let me rephrase my question.

The energy density for a spatially flat universe (without a cosmological constant) is ##\rho = 3 M_{\text{Pl}}^{2}H^{2}.##

How is this formula modified during inflation?
 

FAQ: Hubble scale and energy density during inflation

1. What is the Hubble scale during inflation and why is it significant?

The Hubble scale during inflation refers to the size of the observable universe during the period of rapid expansion known as inflation. It is significant because it determines the size and structure of the universe that we observe today.

2. How does the Hubble scale change during inflation?

The Hubble scale during inflation increases exponentially, which means that the universe expands at an accelerated rate. This rapid expansion is what leads to the large-scale homogeneity and isotropy of the universe that we observe today.

3. What is the energy density during inflation?

The energy density during inflation refers to the amount of energy per unit of volume in the universe during the inflationary period. It is believed to be extremely high, much higher than the energy density of the universe today.

4. How does the energy density during inflation affect the expansion of the universe?

The high energy density during inflation is what drives the rapid expansion of the universe. As the universe expands, the energy density decreases, leading to a slowing down of the expansion rate.

5. What evidence do we have for the Hubble scale and energy density during inflation?

Scientists have used observations of the cosmic microwave background radiation and the large-scale structure of the universe to study the Hubble scale and energy density during inflation. These observations support the theory of inflation and provide evidence for its role in shaping the universe we see today.

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