Well in the sense that GR is math, yes.

The math of 4-space does not require a "something" for the universe to expand "into". Once you can wrap your mind around the concept of the universe not requiring an "outside" to exist, you've taken a big step!

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Any day you wake up on "the right side of the dirt" is a good day.

T. Anderson

That is not a difficult concept the way you explain it.

And it is the accepted best theory too isn't it. But like you say it is math and it excludes an "outside" based on the math, but it doesn't exclude the possibility that in the real nature of the physical universe there is an outside. The math is a beautiful thing, the concept is a beautiful concept, but I wasn't aware that the theory built around the math was considered final. It shouldn't be so extraodinary when someone wants to know if there is anything more than math to base the lack of an "outside" on.

I didn't say that an outside was excluded, just that it was not required!

Nor did I say that it was/is the last word. Just that it is the current working hypothesis.

__________________
Any day you wake up on "the right side of the dirt" is a good day.

T. Anderson

Finite and unbound... For my feeble brain that works fine.

I understand that a expanding universe does not need anything to expand into. Its expanding regardless and taking the space with it.

In this concept. I can envisage other universes with rules of physics different than we know. None of which can I prove or know of... Open mindedness is sometimes hard.

In the balloon analogy, we are working with a 2 dimentional surface on a 3 dimentional object. If you just make the flat 2D surface and make it 3, and make 3D - 4... then you see that EVERY point on that surface is moving away from all the other points...but not just on a 2D suface. Away in 3D (or every direction).

There is no outside, because a 3D flat suface not only doesn't require an outside to expand into, but it can't even have one.

I like the other anaology (take away the true confinement of the box) of a marshmallow in a box, and make the box a vacuum. The marshmallow will attempt to fill the entire void, speading in ALL directions.. not just outward, but inward also, with every molecule moving equally as fast away from every other one.

Unbound (take away the box), and the marshmallow still grows until it is no longer recognizable as a marshmallow, and eventually the individual molecules break down into their costituant atoms, and more and more until there is nothing left to divide. The whole is still the marshmallow, but meaningless to any single thing within it. That is the end of the universe "as we know it". It will never come back together because the void it is trying to fill is unbound.

Yes I understand that this is a sucking rather than pushing apart, but the visual is what I was trying to use.

Does it also allow an exclusion of an inside as well or just one of the sides of the balloon?

The intention of these analogies using the surface of a balloon or of raisin bread rising in an oven is to help people understand how the universe can expand in a way that all points move away from all other points at the same rate as the rate of expansion. This is supposed to represent how 3,1 spacetime works in a way that we can visualize it since we can’t visualize 3,1 (4 D) spacetime directly in our limited 3-D perception.

What I never see is a 3-D graphic that shows the same effect in Euclidean space even though it is simple to draw and the results show the same type of expansion. This can easily be done with multiple points and various angles in a sphere, not just three points in a circle like in the following simple example.

This example demonstrates that if the change in radius in % is applied to the distance that each point is from the center, then movement away from every point within the sphere is in exact proportion to the % increase in the radius. This means that no matter which point you occupy, all other points will be moving away from you at the same rate making it impossible to detect the center of expansion even though is one.

It means that we can explain the type of expansion that we observe in the universe using 3-D space. The analogies are great to describe 3,1 spacetime (4-D spacetime) which we can't visualize but we can easily describe the type of expansion that we actually observe in Euclidean dimensions without resorting to analogies.

Draw circle 1 with a radius of two inches and draw two diameter lines crossing at the center and perpendicular to each other, i.e. like cross hairs in the circle and call one line x1 and one line y1. Mark the points where x1 meets the edge of the circle as N and S, N being at the top like compass points. Mark the points where y1 meets the edge of the circle as E and W with E to the right.

Draw circle 2 with a radius of two inches and draw two diameter lines crossing at the center and perpendicular to each other, i.e. like cross hairs in the circle and call one line x2 and one line y2. Mark the points where x2 meets the edge of the circle as N and S, N being at the top like compass points. Mark the points where y2 meets the edge of the circle as E and W with E to the right.

Put points A1, B1, and C1 in circle 1 as follows:
Put Point A1 at the center where the diameter lines cross.
Put Point B1 one inch from the center on line x1 toward the N.
Put point C1 at point W where line y1 meets the circle 1.

Draw a line from point A1 to point B1.
Draw a line from Point A1 to Point C1.
Draw a line from Point B1 to Point C1.

Point B is one inch from point A.
Point C is two inches from Point A.
Point C is 2.236068 inches from Point B.

Then go to circle 2 which represents an expansion of 100% on the radius from circle 1, i.e. twice the radius:

Put points A2, B2, and C2 in circle 2 as follows:
Put Point A2 at the center where the diameter lines cross.
Put Point B2 two inches (100% expansion) from the center on line x2 toward the N.
Put point C2 at point W where line y2 meets the circle 2.

Draw a line from point A2 to point B2.
Draw a line from Point A2 to Point C2.
Draw a line from Point B2 to Point C2.

Point B2 is two inches from point A2. This is a 100% increase from circle 1.
Point C2 is four inches from Point A2. This is also a 100 % increase from circle 1.
Point C2 is 4.472136 inches from Point B2. This too is a 100% increase.

2.236068 times two = 4.472136 i.e. a 100% increase.

You can use a sphere and add as many points as you want and every point will move away from every other point from time 1 to time 2 by the exact % as the % of expansion.

Again, you are pushing the analogy too far. "Inside" and "outside" are arbitrary distinctions. Think of it as "universe" and "notside", to coin a term.

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Any day you wake up on "the right side of the dirt" is a good day.

T. Anderson

As someone said in another thread, if we replace the word "universe" with "existence" or "reality", it helps to understand it better. What is outside existence? Nothing. It exists or it doesn't. Something is either in (and part of) the Universe, or it is nowhere.

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"If this were play'd upon a stage now, I could condemn it as an improbable fiction."
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Illuminati's Razor-The most complicatedly evil answer is usually the most correct answer. - Fazor
"Every book is a children's book if the kid can read." - Mitch Hedberg
"Distance doesn’t matter much in space, where if you just start a thing off with the right kind of shove, sooner or later it will get where you want it to go." -Frederik Pohl, Mining the Oort

Thank you Kaptain K,
I am quite interested in the topology of the idea and "notside" is a very useful way to look at the fourth dimension.

What I wanted to get at was quantum indicates an inside so there is one I presume if not an outer.

From a topology is it possible to have the one side in the middle?

Another way of putting it is that it's death but external.

I can't find it online, but issue SCA-50607 of Scientific American goes into great detail explaining all of these questions, and on Page 17, there ARE pictures that explain the shapes.

Well, it doesn't make sense at all to question what's outside the universe. IF there's something at all, we won't be able to get there, not even observe it. Even if we could get there, we'll die instantly, because the laws of our universe, that keep us alive, would instantly stop appliying.

So you can say there are giant turtles one atop another

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My God -- it's full of stars!

I like this post. You could be serious and you could be being facetious , and your point would be the same, we will never know, alas.

But just out of curiosity, which of the many hazards out there would kill us "Even if we could get there"?

And as for the turtles, I think that idea has some merit .

Dark Energy (Antigravity)

The antigravity in the universe over powers the gravity causing the universe to expand at an exponential rate. Dark energy is what lies beyond this universe. If one were to maneuver a ship into nothing but dark energy it would brake apart or disolve, hypothetically. Unless one could create some sort of Anti-Antigravity, lol. (mass and energy divided by c squared)

I would say that the existance of total absence is questionable. Because total absence (and total existance) would than be impossible to define in time and space, so you would end up with either of them filling up everything.
I would go for a model when in every point of space you have total existance and total absence merged into a weird unexplainable unity.

Boy, hope I made sense to everybody

I think you made as much sense as it is possible to make when talking about existence and absence-- the real question is, is it possible to make any sense at all? If one is speaking purely scientifically (i.e., as opposed to philosophically), one needs operational definitions of these terms-- and those very definitions answer the question automatically.

I wonder where can you get these operational definitions. Things like life, existance, absence are so BASIC, it is really very difficult to actually make a definition of them...

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I Wanna Go Home CLUB

I agree-- they have meaning outside the realm of science, perhaps even their most important meanings. But science must also use these concepts, and cannot rely on vague common-usage meanings-- we need precise operational definitions, and we have them for those words. The problem comes in when people are not clear if they are using the precise operational definitions, or the vaguer common usages, when they use these words in questions. Put differently, to get a scientific answer, a question must be posed in scientific terms.