Hi, I'm Steve, you can call me Steve. So,
time. They say time is the fire in which
we burn... no wait, that's a movie... and fire
was last year's challenge. So anyway, time
is a dimension. Well that's useful, what's
the dimension? So I presume most of you
are watching this in a classroom. You
in the back, stop picking your nose! And
the rest of you stop laughing, it just
encourages it. So your classroom has
three dimensions: it has a length, from
the blackboard all the way to the back
of the room; it has a width, from side
to side; and it has a height, from the
floor to the ceiling. Now you can move in
any of those dimensions. You can walk
from the front to the back, from side to
side or you can climb the walls to the
ceiling (kids don't climb the walls) Well
time is also a dimension. It's a bit
different because you cannot choose in
which direction you move in it. You are
always moving towards the future. In
addition, in the classroom dimensions you
can go where you want, when you want at
however fast you want (kids don't run in the
classroom). With the time dimension, you do
not get a choice in any of this, you are
moving towards the future at one second
per second and there is absolutely
nothing you can do about it. If you leave
something in the past, you cannot go back
and get it. I'm sorry. Anyway if you take
the three classroom dimensions and
combine it with the time dimension you
basically get our entire universe. We
call this space-time because the three
classroom dimensions, length, width and
height, make up space and the time
dimension makes up time, obviously. Now we
can describe the position of any object
in space time with a set of four
coordinates. You may have heard this term
before, especially if you watch Star Trek.
All it means is a set of numbers
describing the position of something.
Think of it a bit like a mailing address,
only for anything: planets, stars,
mountains, cities, bananas... whatever. So
think of your classroom again.
Where you are sitting right now can be
described in coordinates. You have one
number to indicate where you are along
the length of the classroom, one number
to indicate where you are along the
width, one number to indicate where you
are along the height. Hopefully for
all of you this corresponds to the floor.
Now, you can sit where you are sitting
right now or the person next to you can
sit where you are sitting right now, but
you both can't sit there at the same
time. Whoever just got up to test this, it's
not going to work, sit down and listen. So
this means we need a fourth coordinate
to indicate when you are sitting there,
so a position along the time-dimension.
So with these four numbers we can
describe the position of anything in the
universe, any when in the universe. It
also means that two objects cannot have
the same set of four coordinates.
Everything has to have a unique set of
four numbers. So that's all time is, it's
just one of the dimensions that make up
the universe in which you live. It's not
a predator that stalks us all our lives,
but a companion that goes with us on the
journey. No wait, that's that movie again.
Just Google it. I'm sorry I don't have
any pop culture references to shows you
might actually watch, but I've realized
recently that I am really freaking old,
and I can't go back to when I was
younger because time is a one-way arrow.
Time is also really depressing. You'll
find this out when you get older. But you
know what's not depressing? Science! So
hopefully you enjoyed this, hopefully it
was informative. If you want you can check
out the rest of my videos on YouTube,
Science Is Not Scary, and I hope to see
you again soon. Bye.
