My current mental framework of the universe works in seven dimensions. It's weird, and I haven't seen this theory before, but neither have I seen anything yet that contradicts it. It's perfectly possible something does, but I haven't seen it, and this theory makes a lot of sense to me.
To understand my theory, you'll have to understand two more mainstream interpretations of physics: Eternalism and Many Worlds.
This theory has always fascinated me. I'll give you a quick summary, then explain what it means. Eternalism is the idea that the universe is really a static, four-dimensional object, and that we only see a moving three-dimensional cross-section of it.
This is easier to visualize if we remove a dimension; let's look at film. In a video, the universe is reduced to two dimensions of space—width and height—as opposed to the standard three dimensions of space—width, height, and length. In addition to these dimensions of space, we have a single dimension of time, so a video reduces our four dimensions down to three dimensions, two of space and one of time.
Good so far?
Here's the step Eternalism takes: if time is a dimension, just like width and height, why not represent it in the length dimension, which we currently aren't using. By replacing length with time, we create a visible three-dimensional object that represents the entire video.
To imagine this, think of taking each frame from the video, printing it out on a piece of translucent plastic, and stacking them. The end result is a three-dimensional object representing each object in the scene and their locations at each point in time.
We've represented two dimensions of space and one of time as a single, three-dimensional, static object.
To apply this to our universe, we do the same thing, but with all four dimensions. In the view of Eternalism, the universe is really a four-dimensional static object. We are limited to seeing three dimensions of it, the three dimensions of space. Because the three-dimensional slice we see is constantly progressing, objects appear to move, when we're really only seeing sections of them from different locations in time.
You've heard of this one before. It's the standard explanation behind the "multiverse" idea that's popular in modern science fiction. Whenever a choice is made, the universe splits into two branches, both of which play out, though we only observe one.
In reality, this splitting happens at the quantum level, but we don't need to get that technical for this article. Here's the basic idea you need to know to understand my theory: every time two things could happen, both actually do, but we only observe one of them.
combining the two
Some may have seen where I'm heading. In Eternalism, we only see some of the existing dimensions. In Many Worlds, we only see some of the existing possibilities. In both, there are things we don't see at any given time that nevertheless exist.
For review, let's list our standard four dimensions: x, y, z, Time (x, y, and z are standard variables to assign location in space)
I said this is a seven-dimensional view of the world, so here are my three new dimensions: possible location across x, possible location across y, possible location across z. This adds in Many Worlds, not only representing every location a particle can be located, but every location it could be located at any given time.
Add in Eternalism; we now have a seven-dimensional object representing every possible location of everything in the universe at any given time.
Try paring the model down if you need to visualize it: one dimension of space, one of time, one of possibility across space. That should help.
the eighth dimension
While there's no actual evidence to support this being true, I have thought through a way physics could allow non-paradoxical time travel if we added an eighth dimension: possibility across the time axis.
I'm not going to explain all the nuances of it, but here are the basics:
- To be able to travel somewhere, that location needs to be marked in some way. This is why no time travelers have reached our past: no one has discovered this method yet. Other branches of the eight-dimensional matrix, though, could have had time travelers at the same date if the method of marking a location was discovered then.
- Once a location is marked, a time traveler will appear instantly. After all, the marking only affects the specific location at the specific instance of time, so anyone traveling to a position in time would appear at that instant. In the branches of possibility, though, different time travelers might arrive, though there are also branches where you have decided not to mark the location.
- To avoid paradox, time travelers also travel across the "possibility across time" dimension. This way, if you kill your grandfather, it's not actually the grandfather of your branch, so you can still exist.
- I haven't worked out any math on this, but I think all the conservation of matter and energy stuff is most likely to work out if the way you "mark" a location for time travelers is by time-traveling away from that location yourself. This would also mean it would be impossible to mark a location and not have a time traveler arrive. I'm not sure how the chain would get started, so perhaps this is the requirement that makes the whole thing only theoretical.
Previously, it's been possible to visualize what I've been saying by reducing the number of dimensions to the minimum, but that's not possible here. The minimum number of dimensions to model this would be four (one of space, one of time, one of possibility along space, one of possibility along time), so I absolutely understand if you can't visualize it. It's the more "out there" part of this theory anyway, so feel free to ignore or dismiss it.