From the beginning of the universe to its ultimate fate, these are some of the most out there theories around. Some of them might even be true.
We are living in a computer simulation.
The Theory: The Matrix is real, and we are living in it.
How Likely Is It? Difficult to say – at the moment. Though this sounds incredibly far-fetched, at some point we might be able to test for it. The computer simulation could leave behind a signature from it's underlying structure that we could detect through cosmic rays. Scientists couldn't prove we are in a simulation, but could find evidence that suggests we are.
A 4D black hole collapsed to form the universe.
The Theory: Some physicists think that the universe might have started with the collapse of a 4D black hole, and that the ejected debris formed the universe we live in.
How Likely Is It? We can never truly know what happened before our universe began, so it's certainly possible. And it does address some currently unanswered questions. But it's still early days for this theory, and more research is needed to say one way or another.
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The multiverse.
The Theory: Our universe is just one of many parallel universes, or maybe even an infinite number of parallel universes, in existence.
How Likely Is It? There are plenty of compelling arguments for the existence of the multiverse. And some physicists claim that recent data from the Planck satellite provides evidence for it.
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The big crunch.
The Theory: The universe will end in a "big crunch" as galaxies are pulled back together by gravity, ending in a kind of reversed Big Bang.
How Likely Is It? This theory requires gravity to overpower the force pushing the universe apart. That doesn't look likely to happen, so we should escape this scenario.
