Edit: Sorry, but I had to squeeze in the poll question (as you can see), and in case you can't tell, I want you to read this post, and the article if you have time, before voting.
I'm assuming most of you have heard of theories about there being more than one universe, with other universes containing other copies of ourselves, and other identical universes, and maybe every possible permutation and combination of events being played out in at least one universe of all the multiverse, blah blah blah. I also assume many people, when hearing of this, either say, "Huh?" or "That's crazy!" Well, here's an interesting read:
Scientific American article about parallel universes
It's quite a long read, so I'll do my best at summarizing it:
Level 1 Multiverse
The type of multiverse easiest to understand is the Level 1 multiverse. It's simply space beyond what is visible (and this visibility is continuously expanding as light from the big bang moves outward), with other universes much like ours. The differences come from variations in the initial arrangement of matter, nothing else.
Level 2 Multiverse
This part of the theory is that there are other Level 1 multiverses within an even greater amount of space. Think of it as multiverses within a greater multiverse. Each Level 1 multiverse nucleates like raindrops in a cloud, and during this process variations in quantum fields produce differences between the multiverses. (Eh, read the article if you want that explained.
)
Level 3 Multiverse
This part of the multiverse theory is about there being a vast number of parallel universes, playing out all the possibilities of everything, within the scope of quantum mechanics, fundamental laws of physics, etc. For example, if you flip a quarter in such a way that is completely random, in half of the universes where the quarter was flipped it would land on heads, in half tails.
Level 4 Multiverse
Now here's where it gets interesting. The universes of this level can vary even in the laws of physics.
Why should anyone believe this confusing crap?
Space appears to be infinite in size. If so, somewhere out there, everything that is possible becomes real, no matter how unlikely it is. Also, excerpt from the article about why an entire ensemble of parallel universes can be considered more simple than just one universe (it's the last part of the article, and it refers a bit to previous parts, so it might not make perfect sense unless you read the entire article):
So should you believe in parallel universes? The principal arguments against them are that they are wasteful and that they are weird. The first argument is that multiverse theories are vulnerable to Occam's razor because they postulate the existence of other worlds that we can never observe. Why should nature be so wasteful and indulge in such opulence as an infinity of different worlds? Yet this argument can be turned around to argue for a multiverse. What precisely would nature be wasting? Certainly not space, mass or atoms--the uncontroversial Level I multiverse already contains an infinite amount of all three, so who cares if nature wastes some more? The real issue here is the apparent reduction in simplicity. A skeptic worries about all the information necessary to specify all those unseen worlds.
But an entire ensemble is often much simpler than one of its members. This principle can be stated more formally using the notion of algorithmic information content. The algorithmic information content in a number is, roughly speaking, the length of the shortest computer program that will produce that number as output. For example, consider the set of all integers. Which is simpler, the whole set or just one number? Naively, you might think that a single number is simpler, but the entire set can be generated by quite a trivial computer program, whereas a single number can be hugely long. Therefore, the whole set is actually simpler.
Similarly, the set of all solutions to Einstein's field equations is simpler than a specific solution. The former is described by a few equations, whereas the latter requires the specification of vast amounts of initial data on some hypersurface. The lesson is that complexity increases when we restrict our attention to one particular element in an ensemble, thereby losing the symmetry and simplicity that were inherent in the totality of all the elements taken together.
In this sense, the higher-level multiverses are simpler. Going from our universe to the Level I multiverse eliminates the need to specify initial conditions, upgrading to Level II eliminates the need to specify physical constants, and the Level IV multiverse eliminates the need to specify anything at all. The opulence of complexity is all in the subjective perceptions of observers--the frog perspective. From the bird perspective, the multiverse could hardly be any simpler.
The "frog perspective" is refering to us humans, who only have a limited point of view: that of ourselves, living in this one universe. The "bird perspective" is the point of view of an outside individual who can see everything, looking down on it.
I'll post my opinions and questions later. And finally, feel free to vote in the poll!
I'm assuming most of you have heard of theories about there being more than one universe, with other universes containing other copies of ourselves, and other identical universes, and maybe every possible permutation and combination of events being played out in at least one universe of all the multiverse, blah blah blah. I also assume many people, when hearing of this, either say, "Huh?" or "That's crazy!" Well, here's an interesting read:
Scientific American article about parallel universes
It's quite a long read, so I'll do my best at summarizing it:
Level 1 Multiverse
The type of multiverse easiest to understand is the Level 1 multiverse. It's simply space beyond what is visible (and this visibility is continuously expanding as light from the big bang moves outward), with other universes much like ours. The differences come from variations in the initial arrangement of matter, nothing else.
Level 2 Multiverse
This part of the theory is that there are other Level 1 multiverses within an even greater amount of space. Think of it as multiverses within a greater multiverse. Each Level 1 multiverse nucleates like raindrops in a cloud, and during this process variations in quantum fields produce differences between the multiverses. (Eh, read the article if you want that explained.
)Level 3 Multiverse
This part of the multiverse theory is about there being a vast number of parallel universes, playing out all the possibilities of everything, within the scope of quantum mechanics, fundamental laws of physics, etc. For example, if you flip a quarter in such a way that is completely random, in half of the universes where the quarter was flipped it would land on heads, in half tails.
Level 4 Multiverse
Now here's where it gets interesting. The universes of this level can vary even in the laws of physics.
Why should anyone believe this confusing crap?
Space appears to be infinite in size. If so, somewhere out there, everything that is possible becomes real, no matter how unlikely it is. Also, excerpt from the article about why an entire ensemble of parallel universes can be considered more simple than just one universe (it's the last part of the article, and it refers a bit to previous parts, so it might not make perfect sense unless you read the entire article):
So should you believe in parallel universes? The principal arguments against them are that they are wasteful and that they are weird. The first argument is that multiverse theories are vulnerable to Occam's razor because they postulate the existence of other worlds that we can never observe. Why should nature be so wasteful and indulge in such opulence as an infinity of different worlds? Yet this argument can be turned around to argue for a multiverse. What precisely would nature be wasting? Certainly not space, mass or atoms--the uncontroversial Level I multiverse already contains an infinite amount of all three, so who cares if nature wastes some more? The real issue here is the apparent reduction in simplicity. A skeptic worries about all the information necessary to specify all those unseen worlds.
But an entire ensemble is often much simpler than one of its members. This principle can be stated more formally using the notion of algorithmic information content. The algorithmic information content in a number is, roughly speaking, the length of the shortest computer program that will produce that number as output. For example, consider the set of all integers. Which is simpler, the whole set or just one number? Naively, you might think that a single number is simpler, but the entire set can be generated by quite a trivial computer program, whereas a single number can be hugely long. Therefore, the whole set is actually simpler.
Similarly, the set of all solutions to Einstein's field equations is simpler than a specific solution. The former is described by a few equations, whereas the latter requires the specification of vast amounts of initial data on some hypersurface. The lesson is that complexity increases when we restrict our attention to one particular element in an ensemble, thereby losing the symmetry and simplicity that were inherent in the totality of all the elements taken together.
In this sense, the higher-level multiverses are simpler. Going from our universe to the Level I multiverse eliminates the need to specify initial conditions, upgrading to Level II eliminates the need to specify physical constants, and the Level IV multiverse eliminates the need to specify anything at all. The opulence of complexity is all in the subjective perceptions of observers--the frog perspective. From the bird perspective, the multiverse could hardly be any simpler.
The "frog perspective" is refering to us humans, who only have a limited point of view: that of ourselves, living in this one universe. The "bird perspective" is the point of view of an outside individual who can see everything, looking down on it.
I'll post my opinions and questions later. And finally, feel free to vote in the poll!
