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# Dimensions - String Theory

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Dec 16th, 2017
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__Sign Up__- Some may ask "how can there be more than 3 dimensions?"
- Let's use our third eye and consider a piece of paper with a straight line drawn on it.
- The line has a width, but essentially no height. It is a one dimensional shape.
- If we draw a second line intersecting the first at a right angle, forming a plus, we now have a two dimensional shape.
- It has width *and* height.
- Importantly, within the confines of the surface of the paper it is not possible to slant the lines to be any further apart.
- They are perpendicular to each other so changing the angle of either line will bring them closer together.
- Now let's add a third dimension. We want to add a new line to represent depth.
- Obviously a piece of paper is flat so imagine you've pushed a pencil through the paper right where the two lines intersect. Now our shape has length, breadth and depth but again, all the lines are angled as far apart from each other as it's possible to be.
- If you're completely lost, just imagine your classic Cartesian x, y and z axes.
- Try to picture a fourth line that is perpendicular to all three lines.
- Not easy! Our fourth line needs to be at right angles to the existing three dimensions so that they are all pointing as far away from each other as possible.
- This is only possible in four dimensions. In physics we call the fourth dimension time and we perceive it as change, but mathematically it could be viewed as the same thing.
- From this point we've now run out of casual names for our dimensions, but the principle remains the same. For every step up in dimensions we want to add a new line that is perpendicular to all the others. There's no upper limit to this mathematically, and in physics some string theories only work if we assume the universe is composed of many dimensions beyond the four we can comprehend.
- Where are they? One theory suggests these extra dimensions are curled up extra small similarly to how if you see telephone cables from a distance it only looks like a line but closer up we can see how it is really a three dimensional tube.
- If that sounds crazy then, well remember, that's just a theory:
- A STRING THEORY. Thanks for listening.

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