So I've been watching the video on youtube explaining the higher dimensions, and the fifth dimension is the "possible paths we could take or whatever" and when we make a decision or there's chance we force the probability wave we exist as to collapse.

Which is fine; but then later they say you could travel through the 6th dimension to get to a seperate life in the 5th dimension where you invented something and are succesful. That to me makes it sound like we're existing simultaneously in another dimension,

So the question is does string theory say we're existing in another dimension simultaneously? And if not how could you fold through the 6th dimension to get to a separate 5th dimensional you


im confused, and will donate to a GOOD answer

Our consciousness is localized in the four dimensions we commonly experience. So if you look at a meter stick and notice there are millimeter markings on it, that means there are 1000 little lines on it.

If you imagine each of those little lines as being our physical universe at one exact time, then all 1000 are parallel. You can't really get from one to the other since we can't move along the ruler. If, however, you were able to get up off the ruler (i.e. fold through the 6th dimension) then you could get back on the ruler wherever you chose.

The "folding through dimensions" doesn't really seem to make any physical sense to me so I don't think we'd ever be able to actually do it to find ourselves in a parallel world like that, certainly not without a HUGE power source to do it. But then again, higher level physics is only rarely intuitive, so a lot of the times just because something doesn't make sense doesn't matter at all when it comes to how close to "real" something is.

I know some people who work in string theory and the best advice I can give you is to not think about it. The math is beyond difficult and that's about all there is to it (it's not intuitive at all to anyone but Whitten as far as I know).

fifth dimension? i dont think we're even qualified to guess at what goes on there, if this theory is even true. it would be like the 2d beings, who cant fathom jumping up and down, giving each other their opinions on beings of the fourth dimension.

It depends on the mathematical model used, but the models are actually intuitive; otherwise we couldn't create them. The problem of understanding them is at least two-fold:

1. first, there is trouble with visualization and experience; and,
2. second, there is trouble with characterization

The following video is an attempt to create a visualization based on summaries of mathematical models describing several dimensions (of course the diagrams aren't accurate, so they're actually models of models (summaries) of models (mathematical models) of models (theoretical contructs)):



The issue with visualization is important. Our binocular vision and our wandering experience on earth enable us to only see and perceive what matters to us; it is the space we inhabit, how we inhabit it, and how we interpret our environment that has determined our ability to visualize what we experience. Frankly, we have a lot of difficulty visualizing what we don't experience day-to-day. Further, as our environment and our place in it has evolved, so has our rational ability. Our ability to conceive various dimensions is limited not simply by the evolution of our vision, but also by the evolution of our modes of rationality, which arise from our visiual and other abilities. Due to these problems, our ability to characterize and describe other dimensions (or really to do deep abstract thinking) is impaired by, well, us. It's no wonder that it's confusing. At any rate, I say that the mathematical models are themselves intuitive. They aren't intuitive at the level of everyday experience, but they're certainly intuitive at the level of model-building and abstract mathematics. It's difficult stuff, but it's not impossible to understand if you take it step-by-step and remember the steps. I hope this response helps.

btw, the problem of apparently leaking gravity (it's a weak force so some people think it leaks into our dimension and some people think it leaks out of our dimension) and the problem of dark matter (I tend to think the newer dipole effect idea may be correct) are currently unresolved, so much of the banter surrounding extra dimensions may change; the same goes for how certain problems in quantum physics will be solved. Any time we require the use of admitting "all possible paths" or "all possible worlds", we should be careful to make sure that we're not excluding much simpler (but more difficult to surmise) solutions to problems of physics; hence, when the dust settles, I think the general picture of the cosmos will be radically altered. Just my 2 cents.

EDIT: just adding this, found on d2jsp just now: http://forums.d2jsp.org/topic.php?t=57006070&f=90 "I tend to think the newer dipole effect idea may be correct"

This post was edited by RewtheBrave on Aug 25 2011 02:09pm

Yea I understand we can't perceive it I was just confused as to what the theory was saying. And that was the video I had watched except they added captions which help a lot. So basically, according to string theory, we ARE existing simultaneously in parallel universes?


And also, if dark matter doesnt exsist, what does that mean for dark energy? And if it doesn't exist is that evidence against the big bang?

String theory is currently ambiguous about whether we live in multiple universes--remember that to occupy this place and that place is a violation of the logic of binary opposition. Some quantum physical theory enables such violations as solutions to problems--consider or research the buckyball experiments and how they were resolved. As for us living in multiple dimensions, it appears that we're dispersed within various dimensions, and we may be somehow dispersed within others, too (or they may be within us). This is most obvious when we realize that we exist in 3-dimensional space--and add to that a time dimension (graphically, imagine an x trajectory meeting a y trajectory meeting a z trajectory: this represents us located in space; time adds something different to the mix, just as any further dimensions may add to the mix; however, other dimensions may not include us ... and to get weird, they may yet include alternate universes). Dimensions and universes are not to be conflated

Dark matter and dark energy is predicted by some physics and excluded by other physics. It shouldn't hurt the Big Bang Theory if neither actually exist, since it's just the appearance and apparent measure of their existence which is convenient for the Big Bang Theory. By analogy, if we see a ball and its shadow, we may believe there are two balls instead of one, but by excluding one ball from our theory we don't thereby worry that there are no balls (or no universe). We just need to modify our model of what it means for a ball to exist. I think there are better shots that can be taken at the Big Bang Theory than the potential discovery that there is no dark matter. If we can still explain the phenomenon that we thought was dark matter, then our footing hasn't changed

Well without dark energy what would be the explanation of why the universe is expanding at an accelerating rate

Good question. This gets to the heart of the problem. One solution is to get into discussion of vacuum energy and to suppose that there's a multiverse in which it's both true that our universe is expanding and false that dark energy is required to make up the missing "stuff" in accounting for the rate of expansion of the universe. Essentially, the "stuff" of our universe is only some stuff that has an effect on the expansion of our universe. Far-fetched? I don't know, but it's been proposed. Another way to keep the Big Bang Theory from popping is to suggest an alternative to Einstein's cosmological constant. Some people have suggested a theory of quintessence to replace the cosmological constant. Holographic theory presents yet another alternative: http://en.wikipedia.org/wiki/Holographic_principle -- this links up with string theory, and in particular, brane theory. I know a bit about this, but I don't know much about quintessence ... here's a wiki about quintessence: http://en.wikipedia.org/wiki/Quintessence_(physics)

An alternative to all of the above is to propose that the cosmological constant itself is problematic, because, on certain interpretations of the Lorentz equations, one may derive that the comsological constant is related to the density of the universe; more particularly, if the cosmological constant is relative to density, then its value is not what Einstein supposed. This isn't a shot against the Big Bang Theory, but it would require a re-write. I don't think that removal of dark energy is a requirement of such a re-write, but it would potentially change the calculations for how much dark energy there is. Anyway, it wouldn't be an "argument" against the expansion of the universe, so it's more of an alteration than anything, but I bring it up here because it's relevant to the discussion.

Here's more on the quantum vaccum: http://www.physorg.com/news/2011-08-dark-illusion-quantum-vacuum.html from the topic I linked earlier: http://forums.d2jsp.org/topic.php?t=57006070&f=90
This would completely replace the need for dark energy and it would point toward an answer to the puzzle of how to retain our understanding of the expansion of our universe. One way to think about this stuff is to suggest that there are various levels of stuff to be considered. When you require explanation of really tiny stuff, you dig into quantum physics and string theory; when you require explanation of big stuff you think in terms of relativity and gravity, when you require explanation of middle-sized stuff, you speak in terms of chemistry. This may go without saying. But where questions about weird phenomena or apparent phenomena like black holes, the Big Bang and dark matter intersect in terms of size and dynamics, all kinds of problems arise. So then the response is a kind of patchwork between theories or to isolate some ideas and to try to connect them or expand them to solve such issues. This is a mess, and so something like the quantum vacuum is a runaway idea that may explain what currently boggles physicists. The more I read on quantum physics, the more questions rather than answers seem to arise. But if questions arise, at least there's a chance of progress. On the other side, relativity is running out of stuff to measure and observe. It's getting down to the nitty-gritty small stuff. But the small stuff is screwing with it. And, valiantly, quantum physics is developing novel experiments and ideas that account for at least some of the nitty-gritty stuff. This is the basic reasoning behind acceptance of the plausability or at least the possibility of the correctness of the aforementioned alternatives to dark energy as a way to explain what's missing in understanding the role of the universe's expansion in the Big Bang Theory. The Big Bang may turn out to be a little spark encompassed by an elusive but real theoretical fire.

This post was edited by RewtheBrave on Aug 25 2011 08:35pm

be sure that this is crack pottery nonsense based on wishful thinking which contradicts every serious phsical theory.


No, the extra dimensions are compactified and there is no way to 'unfold' them, if you try to suggest that. There are some stringy models like Randall-Sundrum model with macroscopic extra dimensions, but these have been refuted by recent LHC results (it was shown that Randall-Sundrum II model is dual to technicolor...), the large extra dimension model by Nima Arkani-Hamed will only work if these large extra dimensions are sufficiently microscopic (large means large compared to the natural length scale, the Planck scale).


No, you got it wrong: quantum physics was developed to explain 'tiny stuff'. However, it also correctly explains the 'big stuff', but in most cases it is ok to use classical physics (a limit of quantum physics) for 'big stuff' due to decorrelation. The only thing we can't correctly describe with quantum mechanics is gravity. So when it comes to the 'really big stuff', where only gravitational force matters, we have no other choice than using classical physics, and this is general relativity.
But there are some cases, where the classical limit of gravity (general relativity) is not good enough, which are systems of high mass/energy and low spatial size (black holes, etc). For this, we need a quantum theory of gravity.
Now the ambition of string theory is to provide a theory which describes everything perfectly ('small and really big stuff', and everything inbetween). So string theory would be the theory of everything, and in some limit you would recover general relativity (good enough for 'big stuff', but doesn't work for 'small stuff'), nonrelativistic quantum mechanics etc..