(The following selection is from "Paying It Forward," copyright 2003 by Michael A. Burstein, first published in Analog, September 2003.)
Max Tegmark, a physicist who did much of his work at the turn of the millennium, when I was just out of college, had proposed an interesting take on the Many-Worlds interpretation of quantum mechanics. Many-Worlds, proposed by Hugh Everett in 1957, explained away the paradoxes of quantum uncertainty by postulating that every time a decision has to be made, the universe splits into two, yielding an infinite multitude of realities, sometimes referred to as the multiverse. Well, Tegmark looked at this bizarre concept and proposed an even more bizarre idea of his own, which came to be known by his name.
The Tegmark Hypothesis can be summarized as follows: The only realities you continue to be aware of are those in which you survive.
In other words, suppose you do an experiment where you ask an assistant to push a button which will randomly cause a machine gun to either fire or not fire. You position yourself exactly in front of the gun, so that if the gun fires, you have no chance of surviving.
Here's where quantum mechanics comes into play. It is certainly possible for your assistant and for the rest of us to observe the experiment and recoil in shock at the sudden explosion of a bullet into your chest. But because there are an infinite number of tracks upon which the universe can run, you yourself will never feel the bullet. For you to be a valid observer, your consciousness must follow a track along which it will never--can never--be snuffed out. Because the alternate way to phrase the Tegmark Hypothesis is this: You can never have any awareness of realities in which you are dead.
Again, as I noted here, Max Tegmark will be speaking at the Red Line Bar in Cambridge, MA tomorrow night.