However, when we observe the universe today we find large structure and density fluctuations.

The Big Bang is presumed to have created the density fluctuations that set the stage for the development of structure.

What was the origin of these density fluctuations?

Where were the density fluctuations that seeded the development of large structure?

The researchers also proposed a second possible mechanism, based on localized density fluctuations.

Since we know galaxies and stars do exist, such primordial density fluctuations must also have existed.

"Yes, there was a paper in the Physical Review just recently, on huge density fluctuations."

The shocker here is that these local density fluctuations qualify as independent universes.

In monatomic systems, these waves are called density fluctuations.

During this time it is possible to have a large density fluctuation in a very small volume.