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A was looking a VHS to upload this video ,(My VHS has broken It cant be fixed) when I found this particular part of the Great Carl Sagan in Cosmos ,This among all the 13 episodes inpired me to learn about cosmology & astronomy ,I don't know If this is the right place Due that contains a good and beatiful disccusion matter ,He simply explain what Edwin Abbott in 1884 try to explain in his book

Flatland: A Romance of Many Dimensions, Sagan, as usual in hes very didactical and easy way explain this book ,and make us to think of why certain phenomenom of nature

I invite you to watch it ,opinions ,comments are welcome


http://www.youtube.com/watch?v=Y9KT4M7kiSw

Cool. Now I understand. Really I love stuff about these things.

I'll watch the clip later, but I have a question:
Isn't the 4th dimension Time?   :-?

I'll watch the clip later, but I have a question:
Isn't the 4th dimension Time?   :-?

I believe in this case the distinction is that what is being referred to is a fourth "physical" dimension.  That is, something akin or analogous  to length, width, and height, but in a fourth dimension that we cannot perceive because we exist in three dimensions.

Conceptually, I understand how Sagan explains and represents the fourth dimension.  But, if I think about it too long, my head hurts.  :-[  I think mostly it comes from trying to visualize something that is inherently impossible for us to visualize.  Bleh.  Heh.

I'll watch the clip later, but I have a question:
Isn't the 4th dimension Time?   :-?

Hmm. I thought that also.

Maybe this is just talking about dimensions as directional axis'?

The video is good but doesn't he get a bit involved with the lives of the little 2D people?!

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Isn't the 4th dimension Time?

Forget the author, but I read a book about string theory (not a serious text, more of a Segan-esque intro for the unwashed).  Anyway, the author described as many as 12 dimensions crammed tightly in to sub-atomic space.  We perceive 3 spacial dimensions as (per this author), these are the three extended dimensions.  The rest are curled up tightly on a subatomic scale.  In fact our 3 spacial dimensions may be curled up as well over vast distances meaning if you traveled in one direction long enough you may in fact return to the point you started at, yet no evidence suggests this.

The author went on to explain various processes which may curl or uncurl these dimensions and how string theory shows (based on various elemetry particle's masses and charges) the shapes these curled up dimensions may take.  And since they're sub-atomic it's no wonder why we don't perceive them.  They're simply too small.

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Yes, I agree. Since the word "universe" means "everything that is", there can be no limit to it. Otherwise you'd have The Universe, then Something Else beyond that, but that Something Else has to be part of Everything That Is, so...
To me, it's simple. But I'm not an astrophysicist.


PS- I understand what you said about various physical dimensions; I just thought that time was "ranked" as #4 for some reason.

At any rate, it seems that time and physical space have a lot more in common than most people assume... seems strange at first, but it makes sense.

If the universe is closed then it could indeed include everything that is, and still be finite.

Yes, I agree. Since the word "universe" means "everything that is", there can be no limit to it. Otherwise you'd have The Universe, then Something Else beyond that, but that Something Else has to be part of Everything That Is, so...
To me, it's simple. But I'm not an astrophysicist.


I have tried to comprehend Stirng theory and find it interesting, but there is a sort of "bubble" model of the Universe I heard about once that made a lot of sense to me. Spacetime could very well be sort of "frothy", which would explain a lot.
Thinking about this stuff gives me pleasure and a headache at the same time, just like using spray paint in an enclosed space...

Your "frothy" understanding of the universe is a step in the right direction to understanding how are universe could be finite and how there could be something beyond our universe.  Imagine that our universe is one soap bubble amongst a pile of soap bubbles.  Within our bubble universe is everything we understand and experience, including a specific set of physical laws.  The skin of the bubble is the boundary for our universe.  Other bubbles are other universes, each having their own sets of physical laws, etc.  Only if the skins of adjoining universes break can we go from one to the other, though at that point neither exist as they were and instead form a new universe with new properties that incorporate the two prior separate sets of physical laws and such.  There is a good chance we would not survive such a merger as we are adapted for existence in our universe, not a hybrid universe with conditions that could be vastly different.

This is just one theory explained very poorly by yours truly, but I think you get the idea.  It is just one way of understanding how a universe can be finite in an infinite system of universes.

here we go again

the idea of the unexistace its antintuitive to our common sense, the empty represents a phisic and matematical entity, this entity was created in this big bang,

Imagine a place in the middle of two galaxies ,you'll grab a cristal box of 4 mt quare , cube, ,INSIDE of this box our common sense will said , there is nothing inside maybe a couple atoms of hidrogen BUT there is ,Is a part of our universe ,and it was created ,its a space and time A<-------------------------------->B distance, so the idea of boundaries or the end of the universe ,its very difficult to understand and does not exist ,the shape of our universe can't be understand because we are trap in 3 dimentions (as the video explains) we know for sure that its expanding ,we understand the distortion of space and time due the mass=(gravity)we bearly have an idea of black holes ,they are not doors to travel,.. they are not doorways to another dimentions for the love of god,and the tunnels einstein rossen (wormholes) came by searching unsolved issues of the quamtum mechanics,they don't exist either..
there are many Theorys some of them are very fantastic as multiuniverse (the result of the 80's to the problem of quamtum mechanics matter and antimatter )I have the book of bubble universes, paralel universes,.. Remember in the 70's the Tachquion monopoles particles?(ficticious subatomic particles that could travel millons times faster than light) assuming if this particle were real ,albert einstein model will be on the garbage and the universe wouldn't have no sense at all, these models are made to find and anwers to many issues in the quamptum mechanics.


EDIT:
Of course This is my modest opinion ,I can be wrong, and I respect other's opinion...

(Reaches for aspirin)     :-?

A refreshing post alrot.  I've never given much credence to the numerous "alternate universe" ideas since there simply isn't experimental evidence (not a shred) to support the idea that somewhere waaaayyy over there is an anti-Chris_F typing on an anti-Simviation forum in the anti-verse.  Or that every decision I make spurs an alternate universe in which the opposite decision was made and it goes spiraling off unseen pecking out its own alternate existance.  Sure, perhaps these make handy mathmatical constructs to explain larger (real) phenomena, but they seem an awful lot like simple arbitrary assertions to me.

The string theory stuff and its relationship to additional (tangled, subatomic) spacial dimensions is interesting.  Compelling in the cohesiveness of its theory but again lacking in much experimental evidence.  Although admittedly that could simply be a technology barrier and not a physics barrier.  Still, I just can't make the leap from this to alternate universes.