This is a thread in which we should debate the existence of possible worlds. It is a very vague topic, I know, but this should be a very broad discussion. A "possible world" can be any sort of other-worldly thing you can imagine. So, try to clarify a bit when posting, things like; could possible worlds hypothetically be reached by spaceship? is the space of a possible universe like the space of another universe in any way? can possible worlds have more than three dimensions? do they actually exist? etc. I know that Kharakov is anxious to post, so I'll leave it to him to clarify his position on the matter. Also, Kharakov, it seems like we've nearly run out of things to disagree about in the other thread, so I'm going to take my time and write what will hopefully be a concluding post later.
Ja. =) Good idea for this thread. I would argue no. While new theories on variable speed of light are beginning to take hold in the scientific community, any particle (or spaceship) cannot possibly travel faster than the speed of light. Even electrons are only marginally below the speed of light. To approach the speed of light is to approach the point where mass becomes infinitely large, and volume becomes infintesimally small. At the speed of light, time is constant; the concept of the event horizon (and still nobody has shown that matter actually passes THROUGH an event horizon in a black hole; rather, it is suggested that time "stops" at a certain point, and the matter exists forever in that place with relation to the epicentre of the black hole). Theoretically, our calculations would show time going in reverse if the speed of light could be exceeded, but other calculations show that the speed of light would not be able to be exceeded by any particle, wave, or group thereof. Feel free to disagree. =) I imagine it would be, if one (or more) exists. Though I don't think a possible universe could exist, even according to quantum physics. I should think not. The most commonly used idea of a "possible world" is related to quantum physics, which supposedly has a proof that there is an infinite number of possible universes in which every single possibility is enacted with the same logic. However, the logic does not change in each universe, only the universe's state of its contents. Regardless, quantum physics can prove that there is an infinite number of possible worlds. It can also prove that our universe doesn't exist. That suggests that there is something fundamentally wrong with quantum physics (as it is obvious our universe DOES exist in some way, shape, or form), so one cannot seriously consider quantum physics to be a "proof" of possible worlds. It remains purely speculation based on probably malformed calculations. No. Okay, I can't really say that. I don't believe that they exist. Not that I feel that I shouldn't be "agnostic" on the matter, and say that there is insufficient data ... the problem is, logically, possible universes seem to defy all logic. Empirically, there is nothing reliable which you can use to justify even the suggestion of possible universes. So the question of "do they actually exist?" never actually arises unless, like most of the Hip Forums residents, you have a tendency to think about things that don't really matter. But, that can be dangerous thinking.
I don't know much about quantum physics. But when I think of a possible world, I think of something that exists totally outside of our universe, which suggests that no matter how fast you were going and for no matter how long a time, you will never reach a possible world. If it could be reached, I'd say that it doesn't qualify as a possible world; that's at least not what I think of when I think about possible worlds. I have no idea what an event horizon is, so I wouldn't dare. It seems to me that if it is impossible to ever reach a possible world, then the space of such a world must be very different from the space on this one. I'm not talking about space as in the cosmos, either. I'm talking about space as in the area things occupy. So, the ball's in your court now. How is that an agent from our world could never reach the possible world if the two spaces are somehow related? It also occurs to me that if possible worlds do exist, then in w2 (world two) there could be a possible me sitting in this very same spot, except in another dimension or whatever (let's call the same space in both worlds (0,0)) typing on my computer right now (let's call right now t1). The possible me could also exist in w2 at t1 at (0,1), in which case my possible self would be one metre to the right of where I am right now. In principle, there is no reason why a possible world couldn't occupy the same space as this world, just on a different plane or what have you. If the space in our world and the space in the possible world were in any way related, then it seems to me that I'd be able to turn to my right and see my possible self one metre away. But this is obviously not the case. So it seems to me that no space in a possible world is related to the space of any other world. As far as I know, the idea dates back to Leibniz and was played around with a lot in the 20th century analytic philosophy. I don't know much about the possible worlds theory in QM except that it is not so widely held by physicists as the Copenhagen interpretation, and, just from how strange it sounds, with good reason. I also don't see how there can be an infinite number of possible worlds, unless many worlds can have the exact same content. If such is the case, then I'd like to know how one is to differentiate between two worlds which have the exact same content? That makes sense to me. I can certainly tell you that our universe exists, never mind the possible ones. You just made me think of another good question: Are logical contradictions permissible in some, if not all, possible worlds? I'd say that's a definite "no," since logical contradictions are, well, impossible no matter what universe you're in.
Imagine an ice cream cone. You know that little spot at the very bottom of the cone that, no matter how much godforsaken ice cream you cram into the cone, you will just never fill it up? THAT is like an event horizon. The event horizon is the point where, when you're getting sucked into a black hole, you start going so fast that time literally stops, and you can't possibly proceed further, because you'd be exceeding the speed of light. (that all being theoretical) Since it is not possible to observe what actually happens when the event horizon is reached, we don't actually know. But calculations lead us to think that time just basically stops. I'd like to know that too. The concept of possible worlds has existed much longer than quantum physics has, so perhaps what I said is inaccurate. Rather, when people talk about possible worlds in modern times, quantum physics is usually brought up because it can be used to "prove" that they exist (which it doesn't actually, but some people claim it does). I'd have to agree with you here. =)
