I have been interested in the subject of time travel for ages and have watched various documentaries about it. Fascinating stuff. However, not being that well up on physics I've always found it impossible to understand the scientists when they talk about bending or warping space.
Expressing the idea of spacetime without using the underlying math can't be done satisfactorily. The idea of space and time as a single continuum defies our every day logic. But we can express the idea of curved space without the complex math.
If we have an area of space and want to know if it's warped all we need to do is use rigid "strings" and mark out a large triangle. Let's say we mark out a triangle whose sides are 10,000 km in length. If the space is not warped then when we measure the three interior angles they should be exactly 60 degrees each and the sum of the interior angles should be exactly 180 degrees just as Euclid said they should be. If the space is warped then they will not add up to 180 degrees.
But that's not unusual. Surveyors right here on Earth run into that problem every day because the Earth is not a flat plane, it's a sphere. In other words the 2D space upon which we walk (the Earth's surface) is warped. Surveyors marking out large tracts of land have to account for the curvature of the Earth - or have the land owners live with lot lines that don't connect at the corners...not a good thing.
Try this one. Draw a straight line from the equator directly to the north pole. Turn left 90 degrees and draw another line directly south to the equator. Next turn left and draw a straight line from there along the equator to the point on the equator where you started the first line. You have three lines, all connected together at the corners and you should have a triangle, correct? Correct. You do have a triangle. But you have a triangle whose three interior angles are all 90 degrees - the sum of the interior angles is 270 degrees.
Next draw a huge circle on the surface of the Earth. Physically measure the diameter and circumference of the circle. Divide the circumference by the diameter to calculate Pi. Well, well. Pi does not equal 3.1416 in curved space. Beacuse the surface is curved your diameter is a bit too long - it has a hump in it. That's another way of defining curved space.
Now if you add a time coordinate to the mix and treat it mathmatically as a regular Euclidian space coordinate, "draw" the same geometric shapes. If your calculation for Pi is not 3.1416, if the interior angles of your triangles do not sum to 180 degrees then the spacetime you're looking at is warped.
The problem that really comes in is that you have to treat the time coordinate as a negative complex number, a number with a real part and an imaginary part and...
well, you see why trying to do this with math while keeping it simple is not going to work for us. /ttiforum/images/graemlins/smile.gif
In any case I understand your problem with this idea of curved spacetime. Its not something that appeals to our common everyday sense of logic. But it has been verified experimentally countless thousands of times over the past 104 years as being the way that our universe really works.
