As mentioned in Parts 1, 2 and 3 of this series, the Multiverse is an hypothesis that there are more universes than the one that we can currently observe with our eyes and our various scientific instruments.
Part 1 explained the conventional multiverse idea, Part 2 explained the bubble multiverse idea, Part 3 explained the Many-Worlds multiverse idea.
In this post the holographic multiverse hypothesis and the simulated universe hypothesis will be presented.
(image credit: Wikipedia
The Holographic Universe
Imagine a black hole if you can. It has mass and a gravitational field that is so strong that the escape velocity is greater than the speed of light. As you move further from the center of the black hole the escape velocity steadily reduces until it is exactly equal to the speed of light. This is called the Schwarzchild radius.
This radius defines a sphere and this sphere has an area. If you measure the area of this sphere in the smallest possible unit, the Planck length you can with some math determine the amount of information that area can encode.
Some say that the information that is encoded is enough to represent all of the matter and energy that have fallen into that black hole. Drop an electron into that black hole and the area of the sphere will increase incrementally by enough to represent that electron (technically the theories say the area increases sufficiently to represent the increase in the black hole's entropy when that the electron fell in).
The holographic universe essentially connects the real world of physics with the world of information theory. It is saying that you don't need a volume to represent a universe, it can all be represented on the surface that contains that volume.
So the 3-D nature of our universe may only be apparent. Everything that goes on in our lives and universe instead may be represented by the ever-changing surface of a black hole.
Are we all just like the actors in the Matrix?
(image credit: Pixabay
The Simulated Universe
A simulated universe is the idea that our reality is being simulated in some kind of advanced computer system that is so good it is essentially indistinguishable from what we would say is true physical reality. The computer doesn't even have to be fast enough to keep up in 'real time' because we who are being simulated would never know the difference. Even if it took a million of the computer's years to simulate one second of our time, it would still feel like one second to us.
The computer doesn't even have simulate the entire universe. It only needs to simulate enough of your sensory inputs to make you believe that there is an entire universe out there.
I am not a fan of this one because if a computer is simulating us then maybe a higher computer is also simulating that computer ... and an even higher computer is simulating that computer ... and an even higher computer is simulating that computer ... and so on and so forth. It never ends.
Also why would the apparently simulated universe be so large? Our observable universe appears to be 90 billion light years in diameter. Really what is the point of simulating such a large volume of space and time?
Further Reading
Part 1: The Conventional Multiverse
Part 2: The Bubble Multiverse
Part 3: The Many-Worlds Multiverse
Part 5: The Evidence
Amazon Link (not an affiliate link, I get nothing from this): "The Multiverse: The Theories of the Multiple Universe", ed. Paul F. Kisak, CreateSpace Independent Publishing Platform, December 2015.