If the universe is expanding, what are we filling up?

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be a bit wary with the word transparent, because it is a quite limited term. something like a window might look transparent to us, but trust me, glass does absorb quite a bit of light, in effect, it is only relatively transparent within a certain area of the spectrum, not only that, but about 4% of the light is lost on each surface because of poor impedance matching.

The only truly transparent object would be one that does not interact with the EM field, for example like MrL said, Dark matter.

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Originally posted by Clown

If an object is transparent, you can't see it.

yes you can, what about total internal reflection and diffraction?

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Originally posted by Sayonara³

This has gone on for long enough.

Agreed. How did we get so far off track from the topic of hypershapes? Actually, I know how. There must have been some misunderstanding with what it means for a brain only being able to percieve the world from a 2D screen, because that's how the topic changed into a physics lesson.

I'm not going to get bogged down any further in the semantics of transparency when it's clear that you will change your working definition to suit your current argument.

I can look through a window and see something outside. This is a fact.

Reflected, refracted and unimpeded light from both the window and the objects that I can see beyond it will hit my retina. This is a fact.

Ergo, I see them both at the same time.

There is no reason why they cannot share x,y.

I've already explained why this is not the case. You are only seeing one image (per area) at a time, be in the reflected light or the object directly behind a transparent object. Same applies to the question of colored surfaces.

You can argue light physics all you like, but did it occur that maybe human perception does not operate on a per-photon-positional basis?

I think I have also already established that human perception is dependent on the actual physics. Also, I have also shown that the perception that goes on in the brain is retinotopic, so even then you are still looking at a 2D geometric pattern.

If I am looking at an elephant, and there is a mouse in the way, I see the mouse and the elephant. I don't consider either to be invisible or non-existant just because there is a proportionally insignificant area of elephant obscured.

Umm, that was my point. The mouse will block out any part of the elephant behind it. If we could see fully 3D images, we could see through it. But that also has to do with physics and geometry.

There's no point making an inprecise proposal then arguing semantics for a few hours to prove it's true. Stop trolling.

Excuse me? You are the one who is arguing semantics here. There is nothing inprecise about the proposal that our vision only allows us to view the world from one 2D perspective at a time. That is a scientific fact not only from physics, but from our understanding of the brain. I have explained exactly what this means, and only brought it up to show why we can't visualize what a 4D object looks like (hence the need for clumsy balloon analogies), but you are the one who brought this way off topic with questions of glass surfaces, transparencies and the like. Those are basic physics questions and any amount of thought put into them should allow you to solve them. There is no need to go off topic like that.

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yes you can, what about total internal reflection and diffraction?

I think you covered that above.

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I think it went off topic with the whole "definition of transparent" thing.

I'm still fairly certain that light reflected from the distant object passing through coloured glass carries information from point-to-point about both objects, but at the risk of this digression from the expansion of the universe going on for another 7 pages I think I might just stop talking now...

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Fair enough. Back to cosmology then.....

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if we use the current model to consider both our position in the universe and length in creation until this current point in technological terms, and incorporate that into an idea about planets nearest the edge of our rapidly expanding universe, it intrigues me with the possibilities of someone knowing what lies beyond the edge. I dont look at it as 'humans' discovering what lies beyond, most likely its already been determined by another advanced race; yet i prefer to think of it as 'us', occupants of this universe who at one point, all were in the same awe that we are.. the same speculations... the same conclusions... having them find what, if anything is just past the expanding edge.

Perhaps its inhabited? If u were to go beyond that edge, would the speed (faster than light) be constant? would it cause the vessel to stop? would the force required to break thru this expanse, if there is a tangible barrier, be beyond anything we could fathom? so many questions..

i was going to make a new thread, but searched and found this one so i thought it safe to revive it, is that allowed?

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there is no edge. if you go in one direction long enough, then you will end up back where u started.

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space is expanding into nothing, because there is no space for which it to expand into.

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Can you stop double posting like that? Makes you look like you're trying to get a high post count.

There's an edit button that lets you add on to your post.

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there is no edge. if you go in one direction long enough, then you will end up back where u started.

At least, according to the current model.

There's evidence to support that, but it doesn't make it a flat fact.

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Now if our Space Time shurely is expanding into somthing/nothing.. Then it shurely would have a barrier! No mather how u imagine our space to be there is always a barrier! But it's a completely different question if we can breach this barrier or not, nor even travel near it, both out of FTL recession speeds and our own travel time!

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how can there be a barrier if there is no space beyond said barrier?

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Beacuse betwen space and nothing there is a barrier or change of Space-time to "Nothing" If that change canät be see n as a barrier then what can?

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there is no place for the said nothing so your statement makes no sense

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If our SpaceTime expand... Then is shurely must expand into something! But it doesn't have to be that way either.. but our SpaceTime could take upp "space" out of somtehing that we no notehing about nor might ever be able to do! That's my view atleast.. And sorry now it's sleepy time for me

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Try to imagine a four dimensional object which is the universe. And since the universe is expancing you could say its expanding into a four dimensional "vacuum" which is nothingness

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Try to imagine a four dimensional object which is the universe. And since the universe is expancing you could say its expanding into a four dimensional "vacuum" which is nothingness

Except it's not really expanding into anything, it just IS.

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Phrases such as "it has to expand into something" have no meaning outside* the universe.

* Where "outside the universe" = "not applied within the universe"

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how can there be anything outside the universe. the universe is EVERYTHING. in latin, universe means "one truth."

on a tangent, after further expansion, the matter in the universe will be so far apart, that the density of the universe is so close to zero that the infitessimal decimal wouldn't matter (sorry for the pun)

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theres no outside the universe, as said b4 the universe is making space/time as it expands, however it does said to have a limited size but Ho(Hubbles constant) is not determined so accurately(yet) so unable to calculate the critical density, which relates to the future of the universe. the future being: 1 the universe will get to a size and start contracting(big crunch) or 2 the universe will get closer and closer to a limit but never to reach it (similar to an asymtote on a graph)

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the second is wat i was talking about on my tangent

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as stated, there is no "Outside of the universe", even if you did as Faf said ages ago, and flew out past the know edge so to speak, by virtue of the fact that youre there, means that theres no outside, since you originated from the big bang to start with. it would merely mean that a part of the universe can travel a bit faster than the rest of it

like the old saying; "No matter where you go, there you are"

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like the old saying; "No matter where you go, there you are"

I think that was Confucius.

It's also on the Dedication Plaque on the USS Excelsior NCC-2000.

[/geek]

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Hi everyone, as you can see by my post count, i'm new

Anyways, if the universe is everything and you can't exist on the other side, if you managed to catch up with the "edge" of the universe and breach the barrier, couldn't you just come out from the other side of the universe? Sort of like that really old retro video game (forgot what it was called) where you shoot asteroids, and if you went off the screen you appeared on the other side.

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