It's rather strange, and difficult to accept and believe, but the reality we observe and experience is not the totality of physical reality. How did physicists first come to discover this? Experiments on light produced unexpected results that hinted at this hidden reality. 1/n

This reality is still a minority view among physicists, despite its discovery going back several decades. But it is the truth about this world, our world. People deny it despite the evidence bc the conclusions are so grand. My sole goal here is to disseminate information. 2/

Whether you believe it or not is immaterial. If you disagree that's inconsequential, after all some people think the Earth is flat. So... Reality is a multiverse. Parallel universes. The first person to understand this fully was Hugh Everett, an American physicist, in 1957. 3/

He proposed the idea that quantum theory (which had been around for quite some time) really describes a multiverse. Since then, the multiverse has been the subject/object of intense research, aimed at understanding and making sense of the reality we can not observe directly. 4/

Think of (all) the objects we experience from day to day. These make up a universe. Now, a universe is not a receptacle that holds these objects, a universe is the objects themselves. The totality of said objects (mathematical definition of a set is useful in understanding). 5/

By multiverse, other worlds, or other universes, we mean worlds similar to our own (ignore, for the moment, the question of where they're located in space and time).
Except that we can not observe them. That these other universes exist is a matter of physical fact. It is true. 6/

The purpose of quantum theory is helping us understand these universes. What they're like. In a nutshell reality is multivalued. There exist multiple copies of you but you can not interact with them. Each of these copies interacts only with objects in their respective universe 7/

Note what I'm saying is that this is physical fact (it's not science fiction). Like the fact that the Earth rotates on its axis. The same way we do not feel the Earth rotate, is the same way we can not sense our counterparts in other universes. But they exist. They are real. 8/

Their existence is as real as mine. They interact with the objects in their universe the same way I interact with the objects in mine. It's possible my other counterparts already know about this, if they're as smart, thus to them I exist in the universes they can not observe. 9/

If you're reading this we're in the same universe of course. Interuniverse travel is generally forbidden by the laws of quantum theory. You can not visit any of your counterparts in the other universes.
I know this sounds crazy to the average person, it does to physicists. 10/

But it is the truth about our world. I will not go into the details of how we know this. My aim here is *not* to convince people to believe it. I'm only sharing what I believe, to many, would be new information. Once you grasp the concept, feel free to explore the literature. 11/

But if you're generally disinclined to believe it, I will point this out: all physicists agree that quantum theory is unrivalled in its ability to predict the results of experiments. They also agree it tells us something new about reality. They only disagree on what that is. 12/n