If the universe is finite and curves back on itself, then can the universe be said to be truly expanding? It would seem that a fintie universe would only be moving in on itself, not expanding as much as just shuffling things around. Kind of like the Earth’s Tectonic Plates, plates moving away from each other in one perspective but moving toward one another in another perspective.
An infinite universe would have no boundries. However, would that not mean that at the moment of the Big Bang, as that fluctuation occured and brought everything into being, expelling all matter outward, infinity came into being as well? Can infinity even be brought into being?
You can prove whatever you want if you run fast and loose with your axioms and definitions, and their ain’t no reason to camoflage it with fancy and esoteric forms and equations.
That depends on how you define time. If something exists outside of Space Time, then it would not be limited by Space Time as we know it. All you need are events to take place (such as the ones required to create a Big Bang) and you indeed, have, a form of time.
Collibri is exactly correct. What came “before” the big bang is not a scientific question unless there is some observation that can be made that can tell us something about what came “before” the big bang.
Interestingly enough, there are currently a number of intriguing theories as to what “caused” the big bang. The ekpyrotic model, aka brane theory, suggests that the observable universe was formed by a periodic collision between two three-dimensional membranes imbedded in a five dimensional universe. This theory explains things as well as inflation does and produces some interesting, testable predictions. In some cases it explains things better as it does not require the big bang to have been a singularity. Nor, by the way, does it require that time “begin” with the big bang.
By the way, the observable universe is a sphere with a diameter of about 28 billion light years. We happen to be exactly in the center of this sphere. This is not, however, because we are in some privileged position. Rather, we can only see a small bubble imbedded in a much larger whole. The “entire” universe is likely to be much, much larger. The answer, then to what is outside the “observable” universe, is more universe.
Lib, Jab - I’m with eris. Can we please not go there in this thread?
No, I am saying it does not exist inside Space Time. If you are telling me that it’s impossible for something to exist (in any way at all) outside of Space Time, I’m going to need a cite, and an earth shattering one at that.
It’s as if you were saying you that you can have an apple that wasn’t a fruit, and challenging to provide a cite to prove it, or saying that I need a cite to show a living person can’t be dead.
It’s just true by definition.
An apple is a fruit.
A living person is not dead.
existence requires a space/time context.
Maybe we’re having a semantic difference. Can you tell me what you mean or give me a hypothetical of something existing outside/space time?
The hole in this is that you are assuming that there was a “first cause” in the first place, without any actual evidence that this was the case.
What are you you basing your assessment of what is “clearly impossible” on. Common sense? Intuition? There are many repeatedly verified observations that have been made by modern Physics that are “clearly impossible” according to common sense. It is “clearly impossible” that a photon can be both a wave and a particle at the same time, yet it is. It is “clearly impossible” that something can originate from nothing, but on a subatomic level this seems to happen all the time, through quantum fluctuations. The Heisenberg Principle results in many paradoxes, exemplified by Schroedinger’s Cat, that utterly defy common sense.
[PS. I am not ignoring the posts subsequent to this one. I don’t have time to respond to all at the moment, but will be back later.]
Would that I were disagreeing with this statement. Alas, I am not.
Lib, not to revive this discussion, but it seems clear that if we use “possible” to mean “must exist in some describable world” and “necessary” as “must exist in all worlds” then any being which must exist necessarily if it exists and is described as possible must exist in all worlds. The five following steps add a nice touch, but don’t seem necessary to develop the point.
It isn’t that I want to ditch the topic, because I do enjoy it (and this version contains a step worth arguing vehemently about!), but I’m not sure such an exposition belongs here (sure, I say that after my paragraph above ;)).
Truth
Can we say that the universe has a size if there is nothing outside of it? See how mystical that sounds? Can the universe be so big as to contain itself (God make a rock so heavy etc)?
So you are dismissing my idea because you believe something can be caused, without causation?
I am using logic to decide that a cause requires causation. I don’t know enough about the properties of photons to comment on your case in point example, but in regards to your comment on quantum fluctuations at the sub atomic level, I would like to re-quote you, and I hope I am not taking it out of context:
(Bolding mine).
Tell me, do you think there is a reason why quantum fluctutations occur, but we just don’t know why? Or, do you think seeing as we haven’t found a ‘why’, then obviously there isn’t one?
Similarly, do you believe there is a difference in the events (or non-events) in the lead up to a quantum fluctutation, or do you believe they would be absolutely identical?
Do you believe there is a difference in the events (or non-events) in the lead up to a quantum fluctutation, compared to a non-quantum fluctuation? Or do you believe they would be absolutely identical?
I’m no physicist, but I’ve read a couple of layman’s physics books, and there are various analogies that can help you wrap your mind around the concepts. The one I like best is to imagine an ant on the surface of a balloon. The ant can only crawl along on the surface, so he is in effect limited to 2 dimensions. If he continues straight in one direction, he will eventually end up back where he started. Now imagine that the balloon is further inflated, so that it expands in size. The balloon is still finite, yet it has expanded. But the little ant, although he can now travel further, will STILL eventually end up exactly where he started.
Obviously it’s only an analogy. Since we perceive 3 dimensions, you have to sort of extend the analogy by one dimension, but I think it’s useful at least in imagining the concept.
Sorry if this has been covered already. I tried to read the thread, but it’s very long, and I may have missed it.
Lib I’m not saying it’s not a worthy topic. Perhaps this new formulation merits its own thread. It’s just that this topic tends to be a little complex and requires enormous amounts of time to follow properly. Your modal proofs of the existence of God have the potential to be the hijacks from hell.
It’s not quite the same thing. I can measure the size of my office without knowing what is outside it. Of course, with respect to the universe, such a measurement is purely relative.
It is quite possible, for example, that the “entire universe” does have a positive curvature. This is a proper scientific question (at least potentially) because there are, in principle, measurements that could be made to determine what the curvature is. One could even, theoretically, make a stab at determining the size of the entire universe.
Nor would there be anything mystical in saying that we live in a positively curved “closed” universe. While it is difficult to imagine, it is perfectly coherent. The problems start when you start asking about what is “outside.”
The key point here is that if what is “outside” the universe can’t be observed, the question of what is outside isn’t a scientific question. The scientific answer isn’t really “nothing,” it’s “I don’t know.”
No problem, Truth. I agree. That’s why I moved the discussion elsewhere. And if Colibri or Jab want to pursue it, they can. I should have responded to Colibri’s original question there. Please accept my apology.
I don’t think you’ve got this right Scylla. The universe doesn’t really expand at the speed of light. The big bang was not an explosion. Although there were photons that came into existence shortly after the big bang, they were not traveling away from a single point. They were traveling in all directions and passing by each other in all directions, just as they are now. The photons arose like all other particles from a soup of more fundimental particles. The particles are and always have been traveling in all directions. The only direction that they are all (or at least mostly all) traveling in is away from the past.
Now, you might say that anything outside our event horizon (all light that has reached us since the big bang) is not in the “universe,” but the simplest explanation is that there is space-time outside of our event-horizon that we can’t see yet because no photons have reached us from there.
As our event-horizon expands, more photons that have been in existence since shortly after the big bang hit us in the form of cosmic radiation, but cosmic radiation comes from all directions towards every point, continuously. In other words, as the event horizon expands, we are continually seeing more of where the big bang occured, which was everywhere, from every direction. As far as we can tell, there will always be cosmic radiation, because even a few minutes after the big bang there was already an infinite amount of space in which the photons were flying around.
But in some more philosophical sense, this doesn’t really answer the question of what “caused” the Big Bang, as of course one turns around and asks where the branes and the five dimensional universe in which they are imbedded came from.