# Find out how much the universe grew by during the period of inflation

• AaronKnight
In summary, there is no concrete evidence for inflation as a theory to explain cosmological features, but it is still being studied through experiments like gravitational waves and CMB polarization. It is estimated that a minimum of 60 e-foldings is required for inflation to result in a flat universe. However, due to the limitations of observation, it is difficult to determine exactly how much the universe grew during the period of inflation. Current estimates suggest a minimum expansion of 10^30 in each direction.
AaronKnight
Is it possible to find out how much the universe grew by during the period of inflation after the big bang?

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Not yet. Inflation is still just one theory to explain some cosmological features, and there is no evidence for it (yet- see gravitational waves and experiments investigating polarisation of the CMB).

You can calculate the minimum amount of inflation required by an inflation theory to give us the current flat universe, and I think that's about 60 e-foldings if I remember correctly (so a factor of e^60).

AaronKnight said:
Is it possible to find out how much the universe grew by during the period of inflation after the big bang?
The difficulty is that there is a distinct limit to how far back in inflation that we can possibly observe. Now, we still don't know precisely what inflation was. If we do discover the details of what it is, it is conceivable that that will come along with some specific statements as to how and when it began, which will immediately tell us how much it grew.

The most that we can do at the current stage is place some lower limits on how much it grew. Current estimates are around a factor of at least 10^30 expansion in each direction (though I'd have to look at the specifics).

## 1. What is the period of inflation in the history of the universe?

The period of inflation is a theoretical concept that describes a brief period of rapid expansion that is thought to have occurred during the early stages of the universe, approximately 10^-36 seconds after the Big Bang.

## 2. How do scientists measure the growth of the universe during inflation?

Scientists use a variety of observational and experimental techniques to estimate the rate of expansion during inflation, such as analyzing cosmic microwave background radiation and studying the distribution of galaxies.

## 3. What is the estimated growth rate of the universe during the period of inflation?

The exact growth rate during inflation is still a topic of debate among scientists, but current estimates suggest that the universe could have grown by a factor of at least 10^26 during this period.

## 4. Can we observe evidence of inflation in the universe today?

Yes, there is evidence of inflation in the universe today, such as the uniformity of the cosmic microwave background and the large-scale structure of galaxies. However, direct observations of inflation are still a challenge due to the immense scale and early timing of this event.

## 5. How does understanding the growth of the universe during inflation contribute to our understanding of the universe?

Studying the growth of the universe during inflation allows scientists to better understand the fundamental laws of physics and the origins of the universe. It also helps to explain the large-scale structure of the universe and the distribution of matter and energy within it.

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