Einsteins Field Equation

[illusion88]

So I wanted to start a discussion about time travel. Someone was talking about it in OT, but no one there will discuss with me

Einsteinds field equation says that when wormholes exist, but exist for a very very brief period of time. They open, pinch off and disappear in so short of a timespan that nothing whatsoever can travel through it.

If you have done any reading into this subject, one would realise that the only way to hold the wormhole open is to thread the wormhole with some sort of material that pushes the wormholes walls apart, gravitationally. This "exotic" material, as it is known, has some odd properties. First, whenever a beam of light passes through it the material will gravitationally "defocus" the light. I will try to explain this without a diagram. Imagine that a beam of light is sent through a converging lens before it enters teh wormhole, thereby making all its rays converge radially toward the wormholes center. When the beam emerge from the other mouth, they are diverging radially outward, away from the wormholes center. The wormholes spacetime curvature, which causes the defocusing, is produced by the "exotic" material's mass (because spacetime curvature is gravity and gravity is caused by mass). In other words, the exotic material gravitationally repels the beams light rays, pushing them away from itself and hence away from each other.

Last, the exotic material must have a negative average energy density, as seen by the light beam. We know that gravity is produced by mass and that mass and energy are equivalent (E=Mc^2). This means that gravity can be thought of as produced by energy. Now, take the energy density inside the wormhole (energy per cubic centimeter) as measured by a beam of light (or someone inside the wormhole traveling near the speed of light). The resulting measurment would have to be negative in order for the material to defocus the light and hold the wormhole open. This doesn't mean that the exotic material has a negative energy as measured by someone at rest inside the wormhole, since energy density is a relative concept. Nevertheless, almost all mater that humans have discovered have positive average energy densities in all reference frames.

I am going to have to stop there. This might sound familiar if you have ever read contact by Carl Sagan.

 

[Spinne]

So what exactly is it that you wanna discuss?

 

[illusion88]

Originally posted by: Spinne
So what exactly is it that you wanna discuss?

I suppose I didn't really pose a question. I was hoping this would spawn other comments. So how about this.
How might you use a wormhole to travel through time, or space?
EDIT: I propose we use exotic material to "capture" a wormhole. We may even be able to pull a wormhole out of quantium foam and expand it big enough for human travel!

 

[Xyo II]

well, first of all, i dont see what you are saying about mass and energy being equal. matter can be created from energy and engergy from matter, but there are no known natural phenomenas that cause the change with great efficiency. second of all, this is only one branch of thought from one theory of one concept of the universe. there are many grand concepts of the universe, of which hundreds of theories of their properties pertain to. thirdly, you jumped from a beginning of "wanting to talk about time travel" to "lets talk about non-static traversible wormholes". there are plenty of theories surrounding static wormholes, and once you get into the field of theoretical astrophysics, well, we once thought that the moon was made of cheese. manipulating static wormholes may be thought of as silly in 50 years time, or an everyday occurance. that's why i dont like to give much thought on the matter as of right now, more info is needed about space-time in general, this is a field that is just beginning. once i am in college I'll devote some time into it, but unless you hold a PHD in theoretical physics and stay up to date with the current research, it is pretty hard to even grasp some of the concepts they are dealing with, much less theorizing on a very technical aspect.

oh and btw, "reference frames"? are you talking about relative time frames or what?

 

[illusion88]

Originally posted by: Einstein Element
well, first of all, i dont see what you are saying about mass and energy being equal. matter can be created from energy and engergy from matter, but there are no known natural phenomenas that cause the change with great efficiency. second of all, this is only one branch of thought from one theory of one concept of the universe. there are many grand concepts of the universe, of which hundreds of theories of their properties pertain to. thirdly, you jumped from a beginning of "wanting to talk about time travel" to "lets talk about non-static traversible wormholes". there are plenty of theories surrounding static wormholes, and once you get into the field of theoretical astrophysics, well, we once thought that the moon was made of cheese. manipulating static wormholes may be thought of as silly in 50 years time, or an everyday occurance. that's why i dont like to give much thought on the matter as of right now, more info is needed about space-time in general, this is a field that is just beginning. once i am in college I'll devote some time into it, but unless you hold a PHD in theoretical physics and stay up to date with the current research, it is pretty hard to even grasp some of the concepts they are dealing with, much less theorizing on a very technical aspect.

oh and btw, "reference frames"? are you talking about relative time frames or what?

E=Mc^2
Energy = Mass(speed of light squared). Lots of energy = small ammount of mass. Remember that mass, according to einstein's special relativity laws, is just a very compact form of energy. It is possible, though how is trivial as everything we will discuss here is theoritical, to convert any mass into energy (explosive).

I am not the best writer, when my brain is rolling, I get pretty inarticulate, especially when I am writing something technical. Reading my OP I can see wehre I left some holes, ill try to fill them in and answer your questions.

Wormholes are perhaps the most promising pathways to the past, whereas traveling near the speed of light is the most promising pathway to the future. In my example, it took two singularities to reach through hyperspace to meet and form this wormhold. I will try to illustrate a picture though my words that may help you understand.

Imagine a baloon, our spacetime is on the outside of the baloon. The space inside the baloon is hyperspace. Singularities exist on the surface of this baloon. These singularities are warping spacetime, they appear as if you put a bowling ball on a very loose trampoline. Imagine they are drooping towards the "center" of the baloon. mspaint graphicBy chance occurance, two of these meet, and destroy eachother, creating a pathway between the two surfaces of the baloon. If one were to come across a wormhole, and somehow, again the how is trivial, hold it open with "exotic" material one would create a wormhole.

Here is a little thought expeirment that might get you going. Say you and me have a very short wormhole (something we could reach through). We take one mouth and put it in my living room, and we take the other mouth and put it in your spacecraft that is parked outside my house. For simplicity, assume that when something travels through the wormhole it comes out the otherside instantly. In reality this is not the case, but we are keeping it simple.

I will stay at home, while you fly through space at near the speed of light. Throughout the trip we will hold hands through the wormhole. You depart at 9:00PM January 2006 (as measured by you, me and everyone on earth). You zoom away from earth (at near the speed of light) for 6 hours as measured by you, then reverse the course and zoom back at near the speed of light for 6 hours, arriving in the parking lot exactly 12 hours later, as measured by you) at 9:00pm Janurary 1st 2006. Looking through the wormhole I can see you, behind you, the space craft and much of the parkinglot.

At 9:01PM I look out my window, towards the parking lot, and there I see an empty lot. The spaceship is not there. Instead, if I had a powerful telescope I could see your spaceship flying away from earth.

I go about my life, month after month, year after year waiting, until January 1st 2016, when you return from your journey and land in the parking lot. I go out to meet you , and find that you have aged 12 hours, not 10 years (as expected). You are sitting there in the space ship, with your hand thrust into the wormhole mouth, holding hands with me (10 years ago).

If I were to crawl through the wormhole I would meet younger self, similarly, if my younger self was to crawl through the wormhole, he would meet his older self. Traveling through the wormhole in one direction takes me forward in time 10 years, and traveling through the wormhole in the opposite direction takes me backward in time 10 years. Keep in mind, that it would be impossible to travel back in time beyond Jan 1st 2006 using this particular wormhole.

This is how you could turn a wormhole into a time machine. Does taht make sense?

 

[DrPizza]

That makes perfect sense and addresses the logical question "if time travel was possible, then why don't we see people from the future?"
The answer to that question is because you can't go back in time to before time travel was "invented."

The only part that seems to be bugging me is how are you not holding/holding hands still? i.e. you go about your life, month after month, year after year...

 

[the splat in the hat]

well it just seems like something humans will never do , ever , we cant even respect our planet , we are still literelly sitting on a ''ready to be lit candle'' nuclea style, and we still ethnicly target humans, we still have borders which insites racism, ''we re better than you stay out of my country'' attitude, and so it just seem very far fetched that we will ever achive such a harnessing of energy, on a scale that is incomprehendable, compared to anything humans have done, l for one cant see it ever happening , l believe we may discover a better way but l dont believe ''wormholes'' will ever become a real thing, and lets face it to really believe in such an hypothisis, is more faith than science at this piont in history, theres no evidence to show that a wormhole may even be possible , its really sci fi stuff still, makes for great sci fi, but still .........
And he whom invents a device that can turn energy into matter and visa versa, has singlehandedly destroyed our entire econemy, changed the way transport works, and maybe given time, and evolution a much closer to perfect world than now, at least a much less violent one for humans, humans in my opinion will be very lucky to survive the next 130 years on this planet without some fundamental changes to our pollution output, and when the world leaders in pollution [US of A ] throw all enviromental agreements out the window, ''kyoto agreement'' then the hole world follows knowing the US cant enforce it, and for the last 4 to 6 years our pollution levels have shot up dramaticly , what do the world leaders do ? Nothing , and here we are in a dreamworld talking sci fi, we will be luky to live another 10 generations, and to be frank with MORONS like mr Bush running the biggest military forces every in history what hope do us pissy humans that pay tax have ?