StarTalk Podcast: Cosmic Queries – Multiverse Madness with Max Tegmark

Multiverse Levels

Max Tegmark introduces the concept of the multiverse by explaining its different levels, each with unique characteristics. He describes the level one multiverse as regions of space beyond our observable universe, while level two involves diverse spaces with varying physical laws, as proposed by inflation theory 1. The level three multiverse, often depicted in science fiction, involves parallel realities branching from quantum mechanics 2.

These are multiverses of multiverses.

--- Neil deGrasse Tyson

Finally, Max mentions a fourth level, which is more abstract and less widely accepted, likening these levels to nested Russian dolls 1.

   

Quantum Realities

Quantum mechanics plays a crucial role in the multiverse theory, particularly in the concept of parallel realities. Max Tegmark explains that decisions at the quantum level can lead to the creation of separate realities, where each possible outcome of a decision exists in its own universe 3. This idea is tied to the phenomenon of decoherence, which prevents us from experiencing these parallel realities directly 4.

When you make a decision that really could have gone both ways, you are, in a sense, creating two parallel realities.

--- Max Tegmark

The concept of decoherence helps explain why we perceive only one reality, despite the existence of many 4.

   

Inflation Theory

The inflationary model significantly contributes to multiverse theories by suggesting that space is much larger than our observable universe. Max Tegmark discusses how inflation theory, which extends general relativity, predicts a vast space with multiple universes 5. This model allows for the possibility of infinite universes within a finite space, a concept that challenges our understanding of reality 6.

It's possible to take a little piece of space and make an infinite space inside of it.

--- Max Tegmark

Such theories, while difficult to test directly, have led to significant advancements in our understanding of the universe 6.