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Is there a fourth dimension?
Question Date: 1999-05-10
Answer 1:

Depends how you mean it. Physicists do consider the world a 4-dimensional place: height, width, depth, and time. but assuming you mean a fourth dimension of space...

There might be. But as 3-dimensional beings who can only see, hear, and touch a 3-dimensional world, there's no way for us to see a fourth dimension. that's not to say there *isn't* a fourth dimension, just that we have no way to know it's there. Unless, that is, something weird happens and we FIGURE OUT that there must be a fourth dimension we can't see.

What do I mean? Think about this: suppose you're a 2-dimensional being who lives on a globe. now, you think that the shortest distance between L.A. and South Africa means walking all the way around. and in a 2-dimensional world, you're exactly right. but in a 3-dimensional world, you can go straight thru the globe, and come out the other side, and go a shorter distance (one diameter instead of 1.57 diameters)

Now think about our 3-dimensional world. Maybe a 4-dimensional being sees 3-dimensional space as a twisted piece of paper, with wormholes and shortcuts everywhere. but we can't see that. We might be able to go through a wormhole, pop out somewhere else, look at the stars and realize we had travelled a long way, and make theories about a 4-dimensional world, but we still couldn't see it. If this sounds a lot like Star Trek, it's because Gene Roddenberry had this in mind when he wrote the show!

Or what would we see if a 4-dimensional being walked right past our eyes? What would it feel like to touch them? If you're interested in this, have a look at a book called "Flatland" by Edwin Abbott. It's a "romance" of a 3-dimensional fellow passing through a 2-dimensional world. Give it a read and tell me what *you* think...

Answer 2:

Yes--it is time.All things exist in a place described by the three dimensions and in time, the fourth dimension.

Answer 3:

Dimensions are a concept that scientists use to measure things. For instance, one dimension of yourself is your height. That's something you can measure with a meter stick or a tape measure.

Often we talk about "three-dimensional space", where we use two dimensions to describe an area, and a third to measure height. For many things in our life, three dimensions are enough to describe how they fill up space.

For instance, the classroom you are in has a width, a length, and a height. Considered together, they can be used to calculate the volume of the room. How much air is in
your classroom?

These are not the only dimensions by which we can measure the world. The one you may be thinking of in addition to what I've described so far is time.

Einstein was one of the first scientists to describe an idea called "space-time", where time is considered along with other dimensions in measuring the universe. You can use time along with other dimensions, too, to measure yourself. You or your parents may have made marks on the wall indicating your height as you grew older. To have meaning, those marks usually have a date next to the measurement. The date is a *temporal*, or time measure, of your height. How fast do you grow?

So there are four dimensions. Or perhaps more. You can also measure the world by other dimensions, too, such as temperature. What other ones can you think of?

There is a wonderfully imaginative book called "Flatland: a romance of many dimensions" by Edwin Abbott they you may want to read to learn about dimensions. It is probably in your school or local public library. The author describes what it would be like to live in two-dimensional space, instead of our three-dimensional world.

Dimensions are all about imagination. Mathemeticians often imagine a space with many dimensions in a contruct called a "manifold". Social scientists often talk about the "dimensions of a problem" in order to think about different ways of measuring questions. Computer scientists will arrange groups of numbers into different dimensions for calculations. All of these are examples of how we use dimensions to understand and manipulate the world around us.

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