The many worlds interpretation of quantum mechanics is the idea that all possible alternate histories of the universe actually exist. At every point in time, the universe splits into a multitude of existences in which every possible outcome of each quantum process actually happens.

So in this universe you are sitting in front of your computer reading this story, in another you are reading a different story, in yet another you are about to be run over by a truck. In many, you don’t exist at all.

This implies that there are an infinite number of universes, or at least a very large number of them. (…)

The reason many physicists love the many worlds idea is that it explains away all the strange paradoxes of quantum mechanics.

For example, the paradox of Schrodinger’s cat–trapped in a box in which a quantum process may or may not have killed it– is that an observer can only tell whether the cat is alive or dead by opening the box.

But before this, the quantum process that may or may not kill it is in a superposition of states, so the cat must be in a superposition too: both alive and dead at the same time.

That’s clearly bizarre but in the many worlds interpretation, the paradox disappears: the cat dies in one universe and lives in another.

Let’s put the many world interpretation aside for a moment and look at another strange idea in modern physics. This is the idea that our universe was born along with a large, possibly infinite, number of other universes. So our cosmos is just one tiny corner of a much larger multiverse.

Today, Leonard Susskind at Stanford University in Palo Alto and Raphael Bousso at the University of California, Berkeley, put forward the idea that the multiverse and the many worlds interpretation of quantum mechanics are formally equivalent.

{ The Physics arXiv Blog | Continue reading }

photo { William Eggleston }

ideas, science | May 23rd, 2011