We live our lives in the ordinary 3 dimensions of space and 1 dimension of time. But what if that's not exactly right? What if there are more dimensions that nobody pointed out yet? For example, electricity has multiple dimensions to it; there's voltage, amperage, wattage, etc... Nobody calls those dimensions, that would be silly, right? But think about it, what really is a dimension?
Google defines the word Dimension as meaning: "a measurable extent of some kind, such as length, breadth, depth..."
A lot of confusion can come up from the different ways we use words, so I'll try to be clear. You can define dimensions with math, even with a very high number of dimensions. Basically, for practical purposes, we'll just say that dimensions are a fancy way of looking at exponential factors. In other words, for 2 dimensions we simply count them squared. Three dimensions, cubed. And so on...
Some people talk about theoretical dimensions as if the phrase "multiple dimensions" meant "multiple Universes", but their not wrong to think about it that way. They're just talking about the higher dimensions. Think about it this way, if you put a cardboard box next to another cardboard box, then you have parallel boxes. Each box contains space with 3 dimensions, but the boxes are parallel to each other.
So let's say, just for example, that you have a time machine. And let's also say that you have some emotional issues to work out with your father. Now, if you use your time machine to go back and really ruin your dads life starting with his childhood, then things could happen differently and you might not be born, or worse. But that's a paradox, they say, you can't do that... can you?
Consider this, just by going back in time you also brought the flu back with you. Not only that, but your future flu is decades more evolved than any other flu on Earth when you arrive back in time. By traveling through time you might get some people very sick. Try explaining that to their formerly alive future selves. How would such a paradox be resolved?
It's a funny thing about paradoxes though, there's actually no such thing as a paradox in nature. Sure, nature can seem paradoxical at times, but it never actually breaks down. Nature doesn't stop to double-check the numbers, it solves whatever problem you throw at it and keeps on ticking. But how?
Did you ever notice how when you look in the mirror and wink your Right Eye, the person in the mirror looking back at you winks their Left Eye? But somehow up and down don't get flipped, even though left and right do get flipped. It's not a paradox, it's a mental illusion. Let's assume that the mirror you're facing is to your North, then your Right Eye is East of your Left Eye, by about an inch or two. And when you wink your Eastern Eye, the person in the mirror winks their Eastern Eye as well. Did you catch that?
In one way of looking at the mirror, it seems like a paradox is happening, but it still happens without a hitch. And with the other way of looking at it, the mirror makes sense with no paradox at all. Let's call this Local and Global Relativity. When we look at a mirror in Local Relativity, our senses of left and right seem to be flipped. But looking at a mirror in Global Relativity we can more easily see what's going on.
My theory is that higher dimensions are difficult for people to visualize because we believe that there is only 1 dimension of time. But time is the 4th dimension, it's not a separate thing to measure than space, it's only a dimension. And dimensions are basically just exponents. What's a square squared? A cube.
But what's a cube squared? For practical purposes we can call it a Time-Line (or a sequence of events). So here's the kicker, what is a time-line squared? Let's call that a Time-Plane (or a TimeSquare if you prefer). And a Time-Plane squared would be a Time-Field (or "Volumetric Time"). But is it really still "Time" if it's the 5th or 6th dimension? And does that mean that Time is really Space, and that Space is really Time?
I'll be honest with you, it doesn't really matter what we call it. In fact, nobody really bothered to name the first 3 dimensions in Global Relativity. Nobody bothered to think past length, width, and height from Local into Global Relativity. And most folks just put the first 3 dimensions into the same "Space" name.
Taking measurements is one thing, but interpreting the data is a different issue. Scientists might agree on the measurements of the "Universe", but they have never agreed on how those measurements fit together in the big picture (like pieces of a puzzle). What we do know is that there are at least 4 dimensions, and probably more. But how you look at it is up to you.
Mathematically, if the Universe is infinite, then there should also be an infinite number of dimensions; you can't exceed infinity with exponents, and you can't get a finite result from dividing infinity by a finite value. My conjecture here is that ultimately we may need to admit that dimensions might just be a way for our brains to interpret the natural reality around us. Placing a nice even grid pattern over things always seems to help us visualize how they work. It could all just be human psychology. And no matter how many dimensions we count, there's always going to be one more that we haven't worked out yet.
This is an interesting video about a higher dimensional space-time theory. I don't have anything to do with them, I just thought it was interesting and wanted to share. It's one of many different theories. Try not to get caught up on their talk about crystal patterns, that's just what they call that kind of pattern. But then again, a big part of physics is just human psychology. Reality is far to complicated and abstract to be explained in terms of data, it has to be rendered into explanations with meaningful equations; that's where psychology gets involved. Anyway, here's the video: