could someone explain space-time?

Question

what exactly is space-time?

Answer 1

If I can recall:
In physics, spacetime is a mathematical model that combines three-dimensional space and one-dimensional time into a single construct called the space-time continuum, in which time plays the role of the 4th dimension. According to Euclidean space perception, our universe has three dimensions of space, and one dimension of time. By combining space and time into a single manifold, physicists have significantly simplified a good deal of physical theory, as well as described in a more uniform way the workings of the universe at both the supergalactic and subatomic levels.

In classical mechanics, spacetime is a mere formal option, but in special relativity, space and time are inseparable. The notion of space depends on the observer, as instantaneous events depend on a reference frame. Spacetime is also vital to general relativity, an extension of special relativity that takes gravitation into account.

How many dimensions are needed to describe the universe is still an open question. Speculative theories (such as string theory) predict from 10 to 26 dimensions, but all dimensions other than the usual 4 (3 spatial and 1 temporal) matter only at subatomic scales

Answer 2

Reality can be described with mathematics.

But mathematics is not reality.

For example, if you want to design a video game in which things move around a virtual space, there has to be constrains on them so that objects don't jump from one place to another instantly - unless that function is included in some effect such as a transporter. (Beam me up Scotty.)

A video game has a library if images that can be presented to the player in different ways depending on the input of the player.

As the game gets more complicated various techniques are used to smooth animation instead of having to draw each frame completely. This technique is also use by DVD movies to enable them to show movies without having to draw each frame completely. Computing power and variability reach a point where a solution can not be found in the time given... crash!

In Physics, some problems can not be solved given the number of variables and interactions. Space-Time is a way to solve equations in ways that will produce meaningful answers.

The mathematics converts some of the variables into singularities that can be manipulated as a unit. For example, the graphic of a gravitational system in which the system is presented as a flat plane and gravitational fields are represented by dimples on the plane. The larger the dimple, the more massive the object portrayed.

Look at this statement for example:

"Quite unlike conventional physics, subscribing wholly in the inverse square law, which would make the force of gravity immensely great in close quarters, approaching infinity as two mass objects begin to merge to coincidence, this hypothesis denies such bizarre inimitability of force; reducing it to zero at zero closure." [1]

You can see in this statement how math is used in a logical way to solve a problem when another math would lead to a wholly unacceptable answer. In other words, the scientist is using math to give him an answer he needs and can use rather than another answer that is useless, even if the other answer is correct vis a vis 'reality.'

Space-Time is such a tool. It allows for the useful presentation of material concerning relationships that are as yet beyond our comprehension. It gets the job done. These mathematical tools may function as a catalyst, furthering our understanding without changing the final result. Without such tools, many scientific problems would beyond any solution. With these tools our understanding of 'reality' is furthered and areas in which more research needs to be done can be identified.

;-D Your ideas of what is 'real' are going to change... whether you want them to or not.

Answer 3

space-time means space and time which are supposedly the same thing, as space-time are both curved by gravity(so places with loads of gravity slow down time and stretch space. If you put a ball on a rubber sheet, then you can imagine the sheet as space-time, the object as the object exerting gravity and the curve in the rubber sheet as gravity's effect. As you can see, the closer the rubber sheet (space time) is to the ball (object exerting gravity) the more the rubber sheet (object exerting gravity) curves.

Answer 4

Every day you look at maps. And you think of the world (in 3D of course) as fitting into a map - in other words, things happen in places that you can characterise by co-ordinates on the map and at times you can check on your watch.

But this cannot be right.

The Earth is rotating. And orbiting the Sun. And the Sun is orbiting the local group. And the local group is orbiting the galactic centre.

So your map is wrong the second you have drawn it. New York has already moved by more than its diameter in the time it has taken you to read this.

Your mistake was to treat time differently. If you included time in your co-ordinates you could come up with a more complicated description of spacetime in terms of what is called a manifold. And this would allow you to get your sums right.

Of course, as we are all moving along together we make do day to day with our usual, flawed maps. We can do this because they are co-moving reference frames - they ride along with us. So spacetime is only really needed when you want to describe something really big, or something happening really fast.

Answer 5

The four-dimensional continuum in which all objects are located and all events occur, viewed as a single and continuous framework for existence. Space-time consists of length, width, depth, and time

Answer 6

In order for there to be any more than one dimension there must be time. In order for there to be area or volume there must be time. Time is the hardest dimension for me to grasp. I don't mean minutes or hours, etc. I mean the time in the space time which must be there for the other dimensions to exist. Any sequence must have time and dimensions are sequences.

Answer 7

take a ruler, with that you can messure space: (large, deep, width), take a stopwatch, there you messure time. now take a metric where the time part has different sign from the space part: there you have space-time.