by Heliocracy » Tue Mar 07, 2006 1:55 pm
I think most of you are right, more or less. The idea that there are parallel universes was never suggested by an actual observation, and therefore there's no reason to believe they exist. It's a little like saying you believe in elves because you heard stories about Santa's workshop.
However, String Theorists do believe there are a total of eleven dimensions in our universe: One time dimension, the three extended spatial dimensions we're familiar with, and seven "curled up" dimensions whose spatial extent is too small to be seen with current technology. While we can't see these small dimensions, we can represent them with well-founded mathematics (i.e. we can attach a number to them). There's nothing in our everyday experience to suggest these extra dimensions exist, and there's no observation that points you toward this idea over any others, yet they may indeed play a crucial role in why everything is the way it is.
Can there be features of the universe which cannot be revealed by scientific inquiry? It's entirely possible. But to make conclusions without the ability to test them is a purely arbitrary exercise, and you will never learn anything useful from doing that. It's important to remember that the truth of physics may indeed violate our aesthetic notions--the ultimate theory of everthing doesn't have to be "beautiful" or "sensible," becuase both of those are merely human judgements.
Finally, I disagree that the size of the universe cannot be known. A variety of methods have pinned down the age of the universe at 13.7 billion years, which tells us it's at least 13.7 billion light-years across. In addition, we already have a good idea of the current rate of expansion, and testable theories about how that rate has changed over time. When those "historical" expansion rates are better understood, the size of the universe will be experimentally verified.
I think most of you are right, more or less. The idea that there are parallel universes was never suggested by an actual observation, and therefore there's no reason to believe they exist. It's a little like saying you believe in elves because you heard stories about Santa's workshop.
However, String Theorists do believe there are a total of eleven dimensions in our universe: One time dimension, the three extended spatial dimensions we're familiar with, and seven "curled up" dimensions whose spatial extent is too small to be seen with current technology. While we can't see these small dimensions, we can represent them with well-founded mathematics (i.e. we can attach a number to them). There's nothing in our everyday experience to suggest these extra dimensions exist, and there's no observation that points you toward this idea over any others, yet they may indeed play a crucial role in why everything is the way it is.
Can there be features of the universe which cannot be revealed by scientific inquiry? It's entirely possible. But to make conclusions without the ability to test them is a purely arbitrary exercise, and you will never learn anything useful from doing that. It's important to remember that the truth of physics may indeed violate our aesthetic notions--the ultimate theory of everthing doesn't have to be "beautiful" or "sensible," becuase both of those are merely human judgements.
Finally, I disagree that the size of the universe cannot be known. A variety of methods have pinned down the age of the universe at 13.7 billion years, which tells us it's at least 13.7 billion light-years across. In addition, we already have a good idea of the current rate of expansion, and testable theories about how that rate has changed over time. When those "historical" expansion rates are better understood, the size of the universe will be experimentally verified.