# world lines travel

Discussion in 'Astronomy, Exobiology, & Cosmology' started by Hadeka, Nov 7, 2004.

Messages:
13
hi all, im realy so interest in time travel.

but there is something that i couldnt understand:

What is time lines, world lines and cosmic lines?
how can someone travel through time using different time lines?

i realy would like to understand this with details because if it is possible to travel through time and that anyone can do it ,, i would like to know how.

is it this just a theory as the relativity of Einstein which cannot happen untill now??

or it is a theory that can be achieved as experiences??

anyway, waiting for replies.

thank u

3. ### Just_Not_ThereDo I Look Like I Care?!Registered Senior Member

Messages:
208
Personally, I don't think time travel is possible. Now I have no scientific evidence to back this up, I'm just looking at it logically. I mean how can you go to a time that's already been? Or is yet to be? The only theory that qualifies for me is that of parallel universes. Basically, if the big bang was a natural event (i.e. no interference from God) then if it can happen once, it can happen an infinite number of times. If it's happened an infinite number of times, then there is a universe which is identical to our own. And there is another you, and another me, at this exact moment in time doing the exact same things. And course, there will be another universe which is in exactly the same situation (another me, you) which is happening an hour previous. By travelling to that universe an hour previous effectively you are going back in time, although technically you are not. This is as close as its get to time travel for me, although I don't know much about quantum and whatever, and I know there are other theories about. This works for me though

5. ### DinosaurRational SkepticValued Senior Member

Messages:
4,829
World lines are a relativity concept. The idea is that events happen at a place and time defined by 4 coordinates: (x, y, z, t).

You can view the motion of a particle as a static curve in a 4D space. Such a curve is called a World line.

If you ignore one space coordinate you can get an idea of the concept. Imagine the solar system as being contained in a plane. The sun is in the center of an XY coordinate system. The time axis is perpendicualr to the XY-plane.
• You can view the sun in the normal way as stationary in the center of the scoordinate system. In the world line view, it is a motionless line running along the time (vertical axis).
• You can view a planet in a circular orbit in the ordinary way by imaging a point on a circular path around the sun. In the world line view, it is a helix.
• A decaying orbit is a world line which looks like a certain springs, which are wider at the bottom and which narrow almost to a point.