Eternal Inflation

I am interested in this because it's in a final published paper by Stephen Hawking, who recently passed away, and Thomas Hertog, his colleague. The paper dealt with Hawking's concept of how eternal inflation works.

What is this Eternal Inflation?

Eternal Inflation takes the cosmic inflation period after the Big Bang, when there was this very rapid expansion of the early universe, and postulates that these cosmic inflations are still happening. The cosmic inflation period after the Big Bang was when the universe expanded faster than the speed of light.

The eternal inflation concept is what is responsible for creating multi-universes. This is because these additional cosmic inflations don't produce perfectly symmetric universes because of quantum fluctuations. The idea to take away from this is that this inflation is ongoing, and is still producing more universes.

One thing to keep in mind is that our observable universe appears to be symmetrical and homogeneous. This means that the matter and energy are smoothly distributed throughout. Obviously, this eternal inflation is not detectable because it's outside our observable universe. If there were additional universes outside ours, they would be like bubbles outside our bubble. However, Hawking is not all that certain about this.

Hawking said, "The usual theory of eternal inflation predicts that globally our universe is like an infinite fractal, with a mosaic of different pocket universes, separated by an inflating ocean." He went on to say, "The local laws of physics and chemistry can differ from one pocket universe to another, which together would form a multiverse. But I have never been a fan of the multiverse. If the scale of different universes in the multiverse is large or infinite the theory can't be tested."

Hawking and Herzog used string theory as a way to reconcile relativity and quantum physics using Hawking's favorite holographic principle that states that information in our 3D universe can be encoded on a 2D sphere at its boundary. They postulate that eternal inflation has created a small range of possible universes with no complicate fractal multiverse.

The problem with all of this is that it's theoretical, based on math. There is no solid evidence for eternal inflation. There is evidence for the cosmic inflation period after the Big Bang. If there were eternal inflation it would suggest that universes are constantly being created outside of our universe but that the number of multi-universes is not infinite.

Thanks for reading.