What the heck is the space time continuum?

A.

To put it in very simple terms, the space-time continuum is our
universe. When most people think of dimensions, they only think in
terms of spacial dimensions (up-down, right-left, forward-backward).
These are the dimensions through which we have a certain limited
amount of control over our movement. However, there is another
dimension through which we have no control of our movement, time.
Excluding relativistic effects, time just keeps moving forward. We
can't slow, stop, or reverse it, but it is something with which we
must deal. Whenever we describe an object's place in the universe,
there is a time factor involved as well as a spacial location. For
example, if I give some one my address, that assumes that I am living
at that address right now. It's not the same address at which I was
living just a year ago. So, space and time are both parts of our
universe. However, since most people tend not to think about time in
this context, the term space-time continuum was coined as a means of
emphasizing times importance.

B.

For more details, read the "Space/Time Continuum - a thesis" at :
http://www.west.net/~ke6jqp/spacetime/spacetime.html

If yoou are a "Star Trek" fan, then you'll know that "Time is the fire
in which we burn".  By that analogy, space is the fire-place, and
space-time the four-dimensional arena in which the burning occurs.

Speaking only from my knowledge of the "Back to the Future" movies
(the all time greatest movies of the 80s), the space time continuum
suggests that events are set in time and space just like objects are
set in space at any given time.
If you could observe our universe from outside of time then you could
see every moment throughout eternity and you could see exactly
when/where everything occurs.  Looking at our reality from outside of
time suggests that our future is set (assuming no interference from
something outside of our space/time continuum) much like our past is
set and cannot be changed.

It's definitely a term you'd encounter in science fiction, not in physics class.

>> It's definitely a term you'd encounter in science fiction, not in physics class.

Quite the contrary. The "spacetime continuum" or simply "spacetime" is
the standard term used in physics classes when discussing the theory
of relativity. All uses in science fiction are borrowed from the use
in science.

Has it ever been proven that space and time are continuous?  I thought
the reverse applied, and that both were quantized (viz. the Planck
length and Planck time).  Certainly energy and matter are quantized.

The point is, that it they are not actually continuous, how can there
be a continuum?

I disagree with kottekoe-ga.  Yes, physics classes often talk about
"spacetime" (esp. when studying relativity).  However, I have never
heard "spacetime continuum" in the ~25 physics classes I've taken.

I don't know the status of the theories that xarqi-ga mentions, in
which spacetime is quantized (made of discrete units).  They certainly
aren't proven experimentally, since we're nowhere near reaching the
Planck energy.  However, perhaps this idea has gained general
acceptance anyway.  Relativity assumes that spacetime is continuous,
though.

Biophysicist,

The term spacetime continuum was used frequently in the physics
classes that I took.

In 1907, Hermann Minkowski realized that the work of Lorentz and
Einstein was best understood in terms of a space with non-Euclidean
geometry. He introduced the concept of a "space-time continuum", or as
he called it, a Raum Zeit Kontinuum.

http://www-groups.dcs.st-and.ac.uk/~history/Mathematicians/Minkowski.html

This, of course, became one of the key underpinnings of Einstein's
general theory of relativity.

Sorry if I mislead.  I'm expressing my ignorance over whether space
and time are quantized, and it is probably just my poor grasp of the
significance of the Planck length that makes me wonder if space is
quantized.  I've read a little more now, and while the subject is
discussed, it remains an open question apparently.

I wonder if siliconsamurai-ga would like to share his view as I
believe he is knowledgeable about such matters (and energies).

Hi Metro,

It's all about the direction of time. Forward and outwardly towards
chaos. From order toward disorder. Like leaving the dirty dishes and
unwashed socks without intervention. Chaos! Ironically, leave a
man-made structure alone long enough and nature will eventually take
over to reduce it to the equilibrium of what once resided before it
was created. (Arguable, as it won't happen overnight, but it will
happen). Imaginary time is independant of time direction. Real or
psychological time passes in a forward direction only. Otherwise, we
would be able to remember the future and newly experience the past.
The law of thermodynamics exemplifies the direction of time. A broken
object will not repair itself over time without intervention. Drop a
beer bottle on concrete to test this theory. Check how long it takes
for the beer bottle to jump back into your hand intact. You might need
a few more beers to help you pass the time as you wait. That's the
direction of time.

Phil