Multi (>4) dimension/multi universe theories

Apr 17, 2003
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So have the world of theoretical physics reached the point that the consensus is that there are multiple universes and more than 4 dimensions?
 

Wanescotting

Diamond Member
Feb 4, 2004
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I'm guessing soemone else has been watching "through the worm hole"?

And no string theory has not been proven yet.
 

Wanescotting

Diamond Member
Feb 4, 2004
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Indeed. But from what I understand, multi universe theories are not based on string theory.

Wow, I can't even spell "someone". Tired, I guess.

Anyhow, I thought the theory about strings being attached like a web was leading to multi universe? I was dozing off, so?

Personally, I believe more dimensions do exist.
 

a123456

Senior member
Oct 26, 2006
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Yeah, I just watched it too. I don't think it's exactly a "consensus." It's pretty much going to be impossible to ever prove string theory or multiple universes or more dimensions or any of that higher order stuff. I mean, we don't even know if the current universe is going to contract or expand forever. We have all these hacks, like dark energy, dark matter, 3 forces + gravity, and all that stuff.

It seems like it's not really possible to generate enough energy to see/detect/transfer universes or see higher dimensions. Sad as it may be, I doubt we'll ever know.
 

Sunny129

Diamond Member
Nov 14, 2000
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So have the world of theoretical physics reached the point that the consensus is that there are multiple universes and more than 4 dimensions?

while the concept of multiple universes is still speculative...

...the idea that there are more than 4 dimensions in our known universe however is more than just speculation. think about it - we're already quite familiar with 4-dimensional spacetime (3 spatial dimensions and 1 temporal dimension). but we also know via Einstein's relativity theory that what we experience as the force of gravity is actually the curvature of spacetime itself. in most instances, that curvature is not significant enough for us to literally see its effects. in less common extreme physical environments, like the general vicinity of a neutron star or black hole, the curvature of spacetime is much more significant, and we would be able to see its effects clearly, provided we could get a good view of the object in the first place (which i don't believe we have yet with current technology). but regardless of whether we can only feel its effects or actual "see" its effects, we will never see the actual curvature of 4-dimensional spacetime...and here's why:

to start, let's remove the dimension of time for simplicity's sake. i'm sure i'll get some arguments based on the fact that space and time are inseparable, but again, i'm only temporarily separating them to make things easier to "see." start by imagining a being of only 2 spatial dimensions - that is, he has length and width, but no height. now imagine that this being's universe is a sheet of paper (whose thickness we take to be negligible, and therefore is only a 2-dimensional space of length and width). that being can go forward, backward, left, and right in his universe of 2 spatial dimensions, but he cannot go up or down. in fact, he has no concept of up or down b/c any such movement would take him above or below the 2-dimensional plane that is his universe. now this 2-dimensional being could walk what appears to be a straight path between two points, and if his 2-dimensional universe is genuinely flat (not curved), his path will genuinely be a straight line. if his 2-dimensional universe is curved however, the path that appears to be a straight line to him won't actually be a straight line. a good analogy is the surface of the earth, which is a curved 2-dimensional space (as opposed to the earth in its entirety, which is a sphere in 3 spatial dimensions). right away we can see that the shortest distance between the north and south poles is a portion of any one of the great circles running through both poles if we restrict motion to the 2-dimensional surface of the earth, and that any other path connecting the poles that is restricted to 2-dimensional surface of the earth will be of greater distance. but in the 3-dimensional space that is our reality, we can clearly see that the shortest distance between the north and south poles is actually a straight line through the center of the earth, and that any other path in 3 spatial dimensions connecting the poles, whether it runs through the earth or along its surface somewhere, will be of greater distance. we also see that the great circle (that appears to be a straight line to a human following it from the north pole to the south pole) is actually a semicircle in 3 spatial dimensions, and not a straight line at all...which is in fact why one can often find a shorter path between 2 points in a space with more dimensions than in one with fewer dimensions.

at any rate, just as a 2-dimensional being cannot "see" the 2-dimensional space that is his universe curve in 3 spatial dimensions, we humans cannot see our 3-dimensional space curve in 4 spatial dimensions. we would have to exist in 4 spatial dimensions for us to literally "see" that curvature. b/c we only exist in 3 spatial dimensions, and b/c we cannot see the actual curvature of our 3-dimensional space from within it, we must rely mostly on feeling (and occasionally seeing) its effects in order to detect that curvature. we call these effects gravity. when we add time back into the equation, we see more specifically that we only exist in 4-dimensional spacetime, and that we would have to exist in 5-dimensional spacetime in order to literally see the curvature of our own 4-dimensional spacetime.

so given that we know that spacetime is locally curved (even if it is generally flat on larger scales), and given that we only exist in a 4-dimensional spacetime, there therefore must be an additional dimension for our 4-dimensional spacetime to curve into. so we at least know of 5 dimensions (4 spatial and 1 temporal), even if the evidence is indirect at best, and even though we can't directly "see" one of those spatial dimensions.

if you've stuck with me this long, props to you - i didn't intend on being so long-winded, but its tough to discuss these topics without using a good deal of examples and explanation.
 

C1

Platinum Member
Feb 21, 2008
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Yes, there is also the recent issue that some of the fundamental/universal constants seemingly are not really constant throughout the universe. I recently saw this article :
http://www.dailymail.co.uk/sciencet...-driving-universe-apart-scientists-claim.html

and had to comment that, if Einstein's cosmological constant is actually different in different potions of the universe, then perhaps what is really being observed is the clue that we are embedded in a higher dimensionality.

WE ARE THE PROVERBIAL POND FISH UNABLE TO NORMALLY PERCEIVE BEYOND OUR 4 DIMENSIONAL VERSION OF WHAT WE SEE, THINK OR REGARD AS THE TOTALITY OF WHAT IS ULTIMATELY REAL.
=======================
My sample illustration:
Ms Flatlander believes that there are only two dimensions. Everything looks two dimensional to Ms Flatlander. Ms Flatlander was taught in school and has always understood that A^2 + B^2 = C^2 (You know this as Pythagoras theorem: the sum of the two sides each squared of any right triangle equals the hypotenuse squared). Works perfectly for Ms Flatlander.

But unbeknownst to Ms Flatlander, she really lives on a very large sphere. So Ms Flatlander's theorem is quite true in her local region. But as Ms Flatlander's triangle gets larger & larger, guess what? The theorem breaks down. As the triangle gets bigger, A^2 + B^2 = C^2 becomes less and less true. Ms Flatlander scratches her head and shrugs her shoulders.

But now you know the rest of the story. Ms Flatlander actually lives in a three dimensional world and her theorem breaks down when the triangle size increases because she is using an inadequate formula (Euclidean Pythagoras) because she really is involved with a spherical triangle (non-Euclidean geometry)! The Pythagoras formula is really only an approximation, but works outstanding for small triangles relative to her earth like size sphere (eg, particularly for pencil and paper sized drawings, but even for triangles as large as a mile one a side).

See Law of cosines in non-Euclidean geometry (spherical example):
http://en.wikipedia.org/wiki/Law_of_cosines
 
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Sunny129

Diamond Member
Nov 14, 2000
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yup...i used that same analogy to explain the concept in another thread a while back (can't remember if it was here, or on another forum...might have been Physics Forums)...only i used the earth as the example sphere, and showed that while the sum of the interior angles of a triangle is locally 180° (since the earth's surface is effectively flat over small areas), the interior angles of a triangle with two vertices on the equator, 90° of longitude apart, and the 3rd vertex at either the north or south pole, will sum to 270° since each interior angle would be 90°. simple geometry can be quite fascinating...
 

z1ggy

Lifer
May 17, 2008
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Read up on Tesla...It is interest on some of his views regarding Einstein and his theories. I believe he was working on dynamic gravity? Also he did not believe time was really even "real", that it was just what humans created artifically to measure the past from present from future. I read all these things quiet a while ago, but did he also not believe that the electromagnetism actually caused gravity? I find this to be fasinating, and also very plausible. Magnetic field disruption is an interesting topic and if you have ever read or heard about the "triangle" craft over Phoenix, it is very similar to a "non-existing" government project where they apparently super conduct highly pressured amounts of Hg and other elements in a gyro which produce gravity reducing effects. Why else were many U-boats sunk in WW2 carrying enite loads of Hg? It was b/c the Nazi scientists knew of its special properties and its importance to advanced beyond simple rocketry.
 

Sunny129

Diamond Member
Nov 14, 2000
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I read all these things quiet a while ago, but did he also not believe that the electromagnetism actually caused gravity? I find this to be fascinating, and also very plausible.
i personally do not recall what Tesla specifically believed about the topic, but i also agree that its very plausible based on a few quick correlations: we know that mass causes gravity. more specifically, we know that mass is responsible for the curvature of spacetime, which is in fact gravity. we also know that matter is energy and energy is matter by Einsteind's equation E = MC^2. then by extension, energy, whether it comes in the form of electromagnetism (light) or something else, is also responsible for the curvature of spacetime, and thus gravity.

please note that these are just quick correlations off the top of my head, and i'm not claiming to be 100% confident in them. the reason for my disclaimer is that gravity, or the curvature of spacetime, is most often associated with the presence of mass, and not necessarily the presence of energy, despite their interchangeability. one might make more sense out of this by considering that the path of a beam of light that otherwise always has a tendency to follow a straight path would bend in the vicinity of a massive body. the more massive the object, the more a beam of light will bend as it passes within the vicinity of the mass. i really don't know if light (or more appropriately, energy) will cause other light to bend...that is to say, i don't know if a particular quantity of energy will have a gravitational effect on another quantity of energy in its vicinity.
 

z1ggy

Lifer
May 17, 2008
10,010
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i personally do not recall what Tesla specifically believed about the topic, but i also agree that its very plausible based on a few quick correlations: we know that mass causes gravity. more specifically, we know that mass is responsible for the curvature of spacetime, which is in fact gravity. we also know that matter is energy and energy is matter by Einsteind's equation E = MC^2. then by extension, energy, whether it comes in the form of electromagnetism (light) or something else, is also responsible for the curvature of spacetime, and thus gravity.

please note that these are just quick correlations off the top of my head, and i'm not claiming to be 100% confident in them. the reason for my disclaimer is that gravity, or the curvature of spacetime, is most often associated with the presence of mass, and not necessarily the presence of energy, despite their interchangeability. one might make more sense out of this by considering that the path of a beam of light that otherwise always has a tendency to follow a straight path would bend in the vicinity of a massive body. the more massive the object, the more a beam of light will bend as it passes within the vicinity of the mass. i really don't know if light (or more appropriately, energy) will cause other light to bend...that is to say, i don't know if a particular quantity of energy will have a gravitational effect on another quantity of energy in its vicinity.

From what I remember, Tesla did not think space/time could be "bent" such as the analogy of putting a heavy ball on a trampoline, and seeing it cause an indent. I think his reasoning was something simple such as he thought if that were true, then the spacetime should also deform/bend the object ( Newton's law). Not sure what that would result in, but more or less that is what his theory was.

He was also big into the concept of ether. I know tests have been done to prove it does not exist, but something tells me he was on to something.
 

Wanescotting

Diamond Member
Feb 4, 2004
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Yeah, I just watched it too. I don't think it's exactly a "consensus." It's pretty much going to be impossible to ever prove string theory or multiple universes or more dimensions or any of that higher order stuff. I mean, we don't even know if the current universe is going to contract or expand forever. We have all these hacks, like dark energy, dark matter, 3 forces + gravity, and all that stuff.

It seems like it's not really possible to generate enough energy to see/detect/transfer universes or see higher dimensions. Sad as it may be, I doubt we'll ever know.

Hey, I am okay with that, at least it keeps us busy and studious! Imagine living a world of absolutes that would suck. As silly as it sounds, not trying to figure this out would be even worse.
 

DrPizza

Administrator Elite Member Goat Whisperer
Mar 5, 2001
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yup...i used that same analogy to explain the concept in another thread a while back (can't remember if it was here, or on another forum...might have been Physics Forums)...only i used the earth as the example sphere, and showed that while the sum of the interior angles of a triangle is locally 180° (since the earth's surface is effectively flat over small areas), the interior angles of a triangle with two vertices on the equator, 90° of longitude apart, and the 3rd vertex at either the north or south pole, will sum to 270° since each interior angle would be 90°. simple geometry can be quite fascinating...

This really depends on how lazy you are with your definitions, and is the exact example I use to impress upon geometry students how necessary it is to have agreed upon definitions. Before you can state anything about the sum of the angles in a triangle, you need to define WHAT A TRIANGLE IS! A triangle is generally defined as a polygon with three sides. What's a polygon? A polygon is a closed plane figure composed of straight line segments. So, in Euclidean geometry, no, in your example, the angles do not add up to 270 degrees. The angles add up to 180 degrees, and the triangle lies within the Earth, not on the surface of the Earth. The angles only add up to 270 degrees if you suddenly decide to redefine what a triangle is in your new system of geometry.
 

Sunny129

Diamond Member
Nov 14, 2000
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This really depends on how lazy you are with your definitions, and is the exact example I use to impress upon geometry students how necessary it is to have agreed upon definitions. Before you can state anything about the sum of the angles in a triangle, you need to define WHAT A TRIANGLE IS! A triangle is generally defined as a polygon with three sides. What's a polygon? A polygon is a closed plane figure composed of straight line segments. So, in Euclidean geometry, no, in your example, the angles do not add up to 270 degrees. The angles add up to 180 degrees, and the triangle lies within the Earth, not on the surface of the Earth. The angles only add up to 270 degrees if you suddenly decide to redefine what a triangle is in your new system of geometry.

while i do agree with you that definitions are very important, this has more or less now become an argument over semantics. its like saying concentric circles are not parallel b/c, by the strict definitions of geometry, only lines (and not curves) can be parallel.

i did redefine what a triangle is when i went from Euclidean space (the earth's surface over small distances, which approximates a flat, Euclidean space) to non-Euclidean space (the earth's surface on large scales, which approximates a curved, non-Euclidean space). that's how we went from a 180° triangle to a 270° triangle - we went from Euclidean space to non-Euclidean space. at any rate, i thought i was pretty clear that my example was restricted to the curved, 2-dimensional, non-Euclidean space that is the surface of the earth, and that i wasn't referring to the flat, 2-dimensional, Euclidean space that is the plane common to all 3 vertices of the triangle and "slices through" the earth.

in fact, this type of geometric analysis will allow an n-dimensional being to tell if his universe/space is Euclidean or non-Euclidean without the impossible requisite of having to be outside in a space of n+1 dimensions looking back on his own universe. recall that a 2-dimensional being living in a 2-dimensional space only understands the concepts of width and depth, but not height. he can travel forward, backward, left, right, or in any combination of those directions. but he cannot go up or down - a third dimension does not exist in his space. if his universe/space is a sheet of paper, he cannot look around and simply know that his 2-dimensional universe is truly truly flat and exists only in 2 dimensions, or if his 2-dimensional universe occupies a 3rd dimension by curving into it. but in the above example, he could travel to all 3 vertices of the 3-sided figure that lies in the 2-dimensional space, and then sum the angles he measures at each vertex to find out if his space is either Euclidean or non-Euclidean. if they add to 180°, he knows that the curvature of his space is zero, i.e. his space is flat/Euclidean (at least in his locality). if they sum to more than 180°, he knows his space is non-Euclidean (again, at least locally), and moreover he knows that the curvature of his space is positive (convex), and therefore forms a finite, but unbounded space (just like the 2-dimensional surface of a sphere). if they sum to less than 180°, he knows his space is non-Euclidean once more (again, at least locally), and moreover he knows that the curvature of his space is negative (concave), and therefore forms an infinite, unbounded space (kind of like a saddle whose "edges" extend to infinity).
 

edro

Lifer
Apr 5, 2002
24,326
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The latest I heard, is there are 2+ membranes.
Every time these membranes overlap or intersect, a universe is created.
As the universe cools down to mostly photons, the membranes pull back together, interacting again and creating another universe.

~10^10^10^10^7 universes.
 
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wuliheron

Diamond Member
Feb 8, 2011
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So have the world of theoretical physics reached the point that the consensus is that there are multiple universes and more than 4 dimensions?

Not at all. After 40 years the only interesting thing string theory has produced is some mathematics. The situation is reminiscent of the old theories of the aether which grew increasingly elaborate as physicists attempted unsuccessfully to make them fit the new experimental evidence. Among the newer metric theories are such complex abstractions as "Noncommutative Fractal Geometry" which calls into question even the definition of what constitutes a dimension.

The latest experimental evidence supports contextual theories. For example, the strength of entanglement has been shown to depend upon the number of particles entangled (their context) and entanglement itself has turned out to be subject to Indeterminacy. This implies if we ever do reconcile QM and Relativity the answer may not provide any clear metaphysics whatsoever.
 

z1ggy

Lifer
May 17, 2008
10,010
66
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The latest I heard, is there are 2+ membranes.
Every time these membranes overlap or intersect, a universe is created.
As the universe cools down to mostly photons, the membranes pull back together, interacting again and creating another universe.

~10^10^10^10^7 universes.

And where did you hear this from? Link please.