Because picturing infinity or describing 4 dimesions with a 2 dimensional analogy really does lead to confusion for many people.
Even Stephen Hawking had a hard time relating the equations that describe the Universe with word pictures that would mean something to lay people.
We tend to try and relate to what we are used to seeing, but the truth is that the Universe is a really big place (it is all there is, after all) and we lack the references needed to understand it.
But, the word pictures are all fun exercizes. Which is why I channelled the spirit of the late great Douggie to add my 2¢.
Here again is a difficult-to-visualize concept. Space isn’t expanding into anything. If you go back to the ball/balloon analogy, you need to accept the fact that nothing other than the two-dimensional surface exists. If you mark a number of dots over this surface, and then inflate it, you’ll notice that the dots get farther apart. The critical point of logic here is that, although a real balloon is expanding into the space around it, in our analogy, there is no space around it. Space itself is expanding, but not into anything.
Thanks Q.E.D I will try the videogame thing. I did got through the expanding universe via inflating balloon idea but ouch, seems people (including my beloved) have difficulty grasping that it is expanding itself, not into anything.
It does seem that people have difficulty with, conceptually, ‘the universe is everything that exists’. now that has to mean, by definition, that there cannot be anything outside the universe - a thing cannot exist outside of existence itself right?
You’re not quite getting it. There is no such thing as “nothing” or “nothingness” in cosmological terms. When I say there is nothing beyond the surface of the sphere in our analogy, I mean it literally. There is not a region of “empty space” beyond it in which nothing exists; the surface of the sphere is all there is. This hypothetical surface is space.
Yes, you’ve got it exactly right. It is a difficult concept to grasp, requiring one to let go of basic understanding of how we observe the world around us. We se a ball, but we also see the space surrounding the ball, and have a difficult time accepting a concept which appears contrary to our everyday observation.
So what happens if you fly a spaceship perpendicular to the tangental vector of your universal sphere? Granting that you can get somewhere in your lifetime to see the effects of such and that you’re not crushed by the accelleration up to that speed.
You know, Zunite, I’m sure you’re hurting the Universe’s feelings calling it boring.
How about this: you’ve heard of time being the fourth dimension, right? So if the universe is the surface of a hypersphere, make the radius time. So the center of the universe is the Big Bang. And it makes for some interesting correlations between time dilation due to gravity and mass warping space; any dimples in the surface will actually be “before” the flatter parts.
I’m not sure what you’re trying to ask, since the terms, as you’ve used them, are nonsense. If you mean “what if you try to fly away from the surface of the sphere which represents the universe” then I’ll say it’s impossible. You cannot leave the universe. Conceptually, what you’d be describing is an attempt to move through a fourth spatial dimension, and that simply isn’t possible.
Conceptually, nothing. However, as these “other” universes cannot affect us in any way, and we have no way to observe them since it would be physically impossible to do so, they can be said to effectively not exist.
That’s not what I said. What I said was “can be effectively said not to exist”. In other words, it may very well exist, but as we cannot see it or in any way verify it’s existence, it’s pointless to discuss it in scientific terms.
