-The "universe" as far as scientists are concerned, is really just the visible universe - the area of space we can observe since light has had time to reach us. The colloquial meaning of "universe" is just "everything", and by definition having more than one universe wouldn't make sense.
1. So imagine if the area outside of our universe is far larger than we anticipated, perhaps infinite. If there is matter to match, then that means by sheer chance there will eventually be a planet just like ours, with atoms/etc arranged in such a way that the planet is almost identical to ours. With infinite space, there would be infinite copies of everything and anything that can happen will happen, and happen infinite times.
2. If space has different "phases", then maybe we are just a goldfish that swims in water, never to realize there is ice and steam. In these different areas of space, what we thought were constants and laws of the universe would be different. There could be many solutions to a complicated equation. Maybe we could have thought the length of a year and day were laws and constants, but we know today that's ridiculous... The length of a day and year is simply that way due to chance, and there are many other planets in the universe where the day and year are different. So maybe in these other places with different space, what we thought were laws are not, and there could be say, 10 different type of quarks instead of the usual number.
So then another point was discussed, of parsimony. It would seem that having these long explanations filled with infinite possibilities/etc would be the opposite of parsimony. The argument would be that the equation could be parsimonious... For example, the equation to figure out the flow of water at Niagara Falls can be written on a Tshirt, but figuring out the answer is very difficult.
And finally, something about the 'we live in a simulation' argument... Since advanced beings can make simulations, and if these beings choose to do so, the number of simulations far outnumber the one reality, and due to probability, we are probably in a simulation. Of course, then the question is: What about these advanced beings who created the simulation with us in it? Wouldn't the very same argument apply to them as well?
Some fun things to think about tonight.
Original Podcast:
http://www.samharris.org/blog/item/the-multiverse-you-you-you-you
http://www.samharris.org/blog/item/the-multiverse-you-you-you-you
