Interstellar: 5th Dimension Explained
One thing that is left totally unexplained in the movie is the 5th Dimension. It talks of 5th Dimensional beings. It establishes Time as the 4th Dimension. But never lets out what the 5th Dimension is. It is just told that Future humans might have become 5-Dimensional beings.
1. Who are 5th Dimensional beings?
By referring 5-Dimensional beings, Nolan refers to beings for whom manipulating 4th-D (Time) is a piece of cake. They are beings who are no longer bound by the rules of 4D. They are not able to interact directly with the 3D people. They can only interact with people in 3D/4D, by manipulating gravity, which is explained as force that transcends dimensions.
2. Why has 5th Dimension not been explained in the movie?
Nolan has used 5D as a reference to people who have moved beyond 4D. Who can move across multiple 4D’s (Just like 3D people can move across multiple planes i.e. multiple 2D’s). Something like super humans. I think Nolan might not have wanted to over complicate already complicated fundas. Hence he just left at 5D beings who can manipulate 4D.
3. What is 5th Dimension?
My take is Parallel Timelines. In 5D we can’t just move back and forth in Time (Single line), but also adjacently (adding one more dimension). It means that 5th Dimension adds parallel timelines. In 5D we not just move through past-present-future but also different timelines of each moment of past-present-future. In Tesseract 5D humans, either rendered 3D projection of just one of the parallel timelines or there were all the timelines there, but Cooper concentrated only on one.
4. Why can’t 5D humans interact with 3D humans directly. Why toy with them indirectly?
Maybe they can. Maybe they can’t. Maybe they just choose not to interact directly. Just like StarTrek into Darkness’s opening sequence, where only observations of other evolving planets was allowed, but interference was outlawed. Or as Nolan explained, beings from different dimensions can only interact via manipulating Gravity. As Gravity is the only thing that transcends dimensions.
ArpitGarg's Weblog 
Hi,
I think when talking about dimensions we should avoid confusion. There´s spatial dimensions and there´s the dimension of time. From our 3D perspective, the fourth dimension is time. But from the bulk beings´ perspective, time is the 5th dimension, because for them the fourth dimension would be the additional spatial dimension which constitutes the bulk in which they´re living. I don´t think the bulk beings can move sideways in time, just forward and backward (recall Amelia Brand´s metaphor of descending into the valley and climbing up the mountain) – just as we can traverse a length only by moving forward and backward, but not left or right. Talking of parallel timelines complicates things, because we don´t get to see them inside the tesseract – not because Cooper is concentrating on just one (as you put it), but because there´s actually just one laid out in front of him. I do admit, though, that when trying to make sense of the film´s plot I arrive at alternative timelines, as well – but that´s another story.
“Why can’t 5D humans interact with 3D humans directly. Why toy with them indirectly?”
Because 5D humans (or bulk beings) and the bulk are made of matter that is 4-dimensional, whereas everything in our universe (all the matter, particles, fields, forces) exist in three dimensions. They cannot reveal themselves as they really are, because we wouldn´t understand, but most importantly because it´s physically impossible. So they cannot interact with us directly (by speaking, touching, sign language etc). Kip Thorne explains that if a bulk being were to pass through our brane, it would be invisible for us. We would only see and feel the warping of spacetime caused by its gravity. So the only way for us to ever notice their presence is through gravity, which in theoretical physics and in the film is the only force among the basic forces of the universe that can move out of and through our brane.
Mat
May 20, 2015 at 3:02 am
What you have said can be entirely true and then again maybe not.
I was talking a lecture recently on atom and its structure as we know it. Someone asked me, what are the chances that what we know today inside atom is true. My answer was 0%.
Our whole knowledge can be negated in future with new findings. Similar is the case with 4D/5D.
The fun is that we dont even know there is something as 4D/5D for sure. Just some observations/theory which can have alternate explanations.
We have a habit of relying too much on ongoing research results in our answers, that we are susceptible to domino effect a lot more.
And such movies take advantage of unknown to give explanations to what we do not know.
arpitgarg
May 25, 2015 at 11:05 pm