It is impossible to travel into the past...

CyberEd · Post by **CyberEd** » Mon Jan 03, 2005 7:17 pm

agree with you there - one of the reasons I didn't go studying Math - it has no grip in reality whatsoever

Gowerlypuff · Post by **Gowerlypuff** » Mon Jan 03, 2005 7:38 pm

This is physics, please do not get it confused.

We're talking flat in 3 dimensions, here. I know this might be a stretch of the imagination, but flat just means that parallel lines are always parallel and NEVER meet. If the universe was open or closed, parallel lines would not actually be parallel. They would diverge or converge.

edit: Universe, not world.

Posted Mon Jan 03, 2005 8:06 pm:

[quote="Deacon";p="440365"]And no, the universe is not flat. That makes no sense whatsoever, even if you loosen up the definition of flat to just say that it all rests on a single plane, which is just patently and painfully, obviously false.[/quote]

So you think the universe itself is just the outside of a 4 dimensional sphere? If you travel far enough in a straight line you'll end up back where you started and that two parallel lines will end up meeting?

CyberEd · Post by **CyberEd** » Mon Jan 03, 2005 8:15 pm

a. wasn't it Einstein who said that mass twists the space(time) ?
and so a ray of light driving in a stright line would indeed diverge or converge...

b. go out to some big road and tell me, are the lines on the road marking the lanes parallel ? do they meet ? what about at the horizon ? geometrywise - do they REALLY meet or don't they ?

YH · Post by YH » Mon Jan 03, 2005 8:18 pm

Uhm, I'm don't want to say much about a (light does bend due to gravity, but the connection with space and time, I don't quite grasp it yet), but b can be answered simply because the Earth isn't flat... if you try to draw actual 3D straight lines, they should eventually be shooting out into space, not going along in a circular track (if you want to road to go along the latitude of the earth, for example).

EDIT: Misread your statement. You were talking about perspective then....

Gowerlypuff · Post by **Gowerlypuff** » Mon Jan 03, 2005 8:19 pm

a) I'm talking lines of no mass. If space is open or closed it is non-euclidian. Look that up.

b) that's called a field of view and perpective. I'm talking two lines that are parallel and you FOLLOWING them. They'll get closer together and then converge. Like this

CyberEd · Post by **CyberEd** » Mon Jan 03, 2005 8:31 pm

that's EXACTLY the answer I wanted to hear.

if you follow the lines on the road they would never meet. however the earth (being a sphere) is not euclidian - and you WILL come back to where you started.

what am I trying to say ? that while the universe might be flat or spherecal drawing massless lines is impossible. the closest you can get is lines of light and these, do not conform with the old greek.

Grumlen · Post by **Grumlen** » Mon Jan 03, 2005 8:41 pm

Going back tot he original topic . . .

Blaze, I'm not sure why you aren't understanding this. You are NOT going to experience time that you have already experience. Sure you start seeing the backside of my train, but thats because in the same amount of time my train moved faster. My present is beyond your present. The only way you would be travelling into time that you had already been in would be if you managed to see the back of YOUR train while still looking in the direction it is moving in. The only way that would be possible would be if time were a loop, which is NOT an assumption that you made. I said that time is relative because we are always travelling through it. It is known that if one ever managed to actually STOP moving in any one dimension they would create an absolute reference point for that dimension. Unfortunately, due to things like the Heisenberg Uncertainty Principle, stopping like that is impossible. Thus, we have to deal with relativity.

Other than seeing the back of your own train, I've already said all of this yet you see to be ignoring it.

Gowerlypuff · Post by **Gowerlypuff** » Mon Jan 03, 2005 8:42 pm

Oh my god you're hurting me.

Look. You're really not getting this. Roads are man-made and, as such, you can do stuff with them like keep them built like this.

The Lattitude lines are parallel. I think you'll find they meet at the poles. You draw two lines from the equator and draw them due north (either one) and thus they are parallel. Look at that! They meet!

Spongiform · Post by **Spongiform** » Mon Jan 03, 2005 9:11 pm

Latitude isn't parallel BECAUSE they meet at the poles. I learned that in fourth grade.

Gowerlypuff · Post by **Gowerlypuff** » Mon Jan 03, 2005 9:30 pm

No, they ARE parallel in two dimensions, but they're on a closed surface. Looking from the third dimension you can see they're not, because they are travelling on a curved surface. This is exactly what we mean with the universe. If it's a closed surface (of a hypersphere) then things which are parallel to us in 3 dimensions will meet.

Rileyrat · Post by **Rileyrat** » Mon Jan 03, 2005 9:55 pm

[quote="Nitz Walsh";p="439249"]Relativity and quantum physics are just theories with complex mathematical equations surrounding them... That means you can prove them wrong, or find loop holes to get around them...[/quote]

As far as relativity goes they have proven it. With atomic clocks and knowing the rate that they lose time makes it possible. A few years back they did the math, according to relativity, and figured out how much slower time would pass for a person on an airplane going XXX mph. Also factored in was the acceleration from 0 to XXX and deceleration from XXX back to 0. They then put an atomic clock on an airplane and sent it a prespecified distance and back to point of origin. The clock that was on the airplane was off by the exact amount the math told them it would be. For fun they then figured out how much longer you would live if you were on a plane at the speed they used for the duration of the average human life, came up to be something like 6 seconds lol.

Post by **Blaze** » Mon Jan 03, 2005 10:08 pm

Blaze, I'm not sure why you aren't understanding this. You are NOT going to experience time that you have already experience. Sure you start seeing the backside of my train, but thats because in the same amount of time my train moved faster. My present is beyond your present. The only way you would be travelling into time that you had already been in would be if you managed to see the back of YOUR train while still looking in the direction it is moving in. The only way that would be possible would be if time were a loop, which is NOT an assumption that you made. I said that time is relative because we are always travelling through it. It is known that if one ever managed to actually STOP moving in any one dimension they would create an absolute reference point for that dimension. Unfortunately, due to things like the Heisenberg Uncertainty Principle, stopping like that is impossible. Thus, we have to deal with relativity.

I don't know why YOU'RE not getting this. I'm not comparing myself to one other person. I'm talking about accellerating the WHOLE of the universe for ALL time around me. EVERYTHING but me. The rest of the universe's past will be my present. My personal time? No. But that's why I clarified to say I would be experiencing the past. The numbers might be advanced, but the things there would be of the past.

Gowerlypuff · Post by **Gowerlypuff** » Mon Jan 03, 2005 10:17 pm

Blaze, the only thing you would need to do is the time. If you accelerate one thing up to a certain speed (say 0.9c) and have it moving at that speed and have another thing stationary. When one goes past the other (at the constant speed of 0.9c). Each will experience the other being shorter and slower. The one "stationary" would see the other contracted and would hear (if possible), say, the ticking of a clock there as being much slower, with the time dilation and all. However, for the one moving at 0.9c, his frame of reference says he's not moving (and he's not undergoing any forces to tell him otherwise - let's ignore air resistance, etc. He's in space). He will see and hear exactly the same things going on for them. It's known as the twins problem. You put two twins really far apart and fire them off in opposite directions towards each other at 0.7c. For one twin, the other seems squashed and slowed, but for the other the same applies. Yes, anyway.
As it would be relative, the physical universe does not need to be moved by any external force, as that has the precise same effect of you moving backwards, relatively (I may be wrong, as it would be accelerating. Lots of force needed, not too sure). All that would be necessary would be to speed time up. Other than being completely impossible, that's fine.

Post by **Blaze** » Mon Jan 03, 2005 11:35 pm

And that's what I meant. You wouldn't really be moving backwards, but you would be experiencing time through which the rest of the universe had already passed. I only said you need to move all dimensions, because, quite frankly, I don't know if their might be some sort of collision problems or something with yourself from one time, and something else from another.

Spongiform · Post by **Spongiform** » Tue Jan 04, 2005 1:35 am

But the

time through which the rest of the universe had already passed

would be moments which happened AFTER you started speeding the universe up, wouldn't it?

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