
Is there a fourth dimension?
  Answer 1:
Depends how you mean it. Physicists do consider
the world a 4dimensional place: height, width,
depth, and time. but assuming you mean a fourth
dimension of space...
There might be. But
as 3dimensional beings who can only see, hear,
and touch a 3dimensional 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 2dimensional 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 2dimensional world, you're
exactly right. but in a 3dimensional 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 3dimensional world. Maybe a
4dimensional being sees 3dimensional 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 4dimensional 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
4dimensional 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
3dimensional fellow passing through a
2dimensional world. Give it a read and tell me
what *you* think...
  Answer 2:
Yesit 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
"threedimensional 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 "spacetime", 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 twodimensional space, instead of
our threedimensional 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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