So time is the effect of light, influenced by gravity. THE SPEED OF LIGHT VARIES. This is true. It's also been proven that light bends around planets, gets refracted, and can even be trapped like in a black hole. This, I believe is due to the effects of desnser space particles, I'll call it aether from now on to fall in line with what has already been theorized.
In the illustration, you can see the effect on the densities of the aether imposed by the earth, sun and moon (not to scale). The aether is dense but thin where the earth faces the sun due to each of their repulsive forces. This effects not only the tides, but ionosphere activity. It is well known to AM radio broadcasters that at night, their frequencies are bounced back from the ionosphere, sending their station's signal thousands of miles, which is why many AM stations are forced to go off the air at sundown. I propose this is because the ionosphere is thinner during the day caused by the repulsive forces of the sun and earth combined. At night, it returns to proper density, which will bounce back frequencies under 30 Mhz. The density of the aether will also effect how light, another form of electro magnetic energy, responds. It will go slower through the denser areas, even bend and refract, this has also been proven, but has been hypothesized that it was due to "gravitational forces."
Here's a simple illustration for my next point. Light travels at about 186,000 miles per second. Let's just say that Mars is 1,860,000 miles away. So it takes light 10 seconds to get there. If I can get to Mars in 5 seconds, I can see the past. I would have to go faster than the speed of light, just to see it. If I were moving at exactly the same speed as light, then time would stand still for me, but everything else would continue as usual, bringing me into the future. (Right now, we are all traveling into the future, but at a much slower speed, and everyone is traveling at the same rate, I think). If I were moving faster than the speed of light, I would catch up with the light from the past. Now, in order to travel into the past, I would have to stay in one place moving faster than the speed of light. Here's the conundrum... speed is a function of distance over time (ie. miles per second), yet I want to stay in one place. So how can I move faster than the speed of light and stay in one place? The answer seems simple enough... by stopping light.
Here's a bad sketch for a light accumulator, which would both stop light, as in a black hole, and continue to accumulate it through time. The perimeter would have to be made of a few layers of one-way glass to allow light to enter, but not escape. That will be like the event horizon of a black hole. Since light is both a particle and a wave, it should begin to fill up the space, so it would be best to start with a vacuum inside. There shall come a point of critical mass where the orb cannot handle the density of the photons inside, and will burst unless the power is harnassed and/or released. It may be interesting to do this experiment first with a flexible material that resembles one-way glass, and fill it up with light much like a balloon. Just by it's nature, and it's name, light must be lighter than air, so the structure should be given lift, much like a helium balloon, but filled with pure energy rather than matter. My theory suggests that an actual event horizon is just a very densely packed aether resulting from the collapse of a star. The collapsed star is small, and dense, and hot. This pushes away a lot of aether, but because the mass is small, the aether is very tightly packed around it, bouncing back all the electomagnetic forces, including the visible spectrum. The aether around earth is only dense enough at night, like I said, to bounce back frequencies up to 30 Mhz. Radio frequencies have much longer wavelengths than visible light, and so does infra red, which is also bounced back to us. The black hole's aether density must be that it bounces back even the shorter wavelengths of visible light, and possibly even the shorter ones like UV, xrays, gamma rays, and cosmic rays, but those I'm not sure of. What I do think is happening, though, is that all this light that can't escape keeps adding mass to the black hole. It may be so dense as to have turned light photons into a more liquid state, like plasma, or even a solid. Yeah, that's right, I'm proposing that it's possible to freeze light, and if my light accumulator was strong enough, it can do it, too. As the structure within the black hole grows, the aether will begin to thin out as it will have more room to spread out. Once it is thin enough, you either have a "big bang" as all the pent up energy is released all at once, and all the matter gets shot back out in all directions, or you have the formation of a new star, I'm not sure which, and it would probably depend on the matter that got "sucked in" as well.
So what's the effect on time, you ask? Since light records time, time is halted within the blackhole, but it also continues to accumulate until critical mass. Here, past and present exist simultaneously. The future doesn't exist yet. The blackhole can only store light from the times it has seen. So if I make a blackhole on March 28th, 2002, that will be the earliest point in the past you can travel to, if indeed you can travel in time. So far, all I know that my accumulator can do is record time. Hypothetically, it has frozen time, but then you can argue the same thing for a camera. Like I said before, to travel into the past, you need to move faster than the speed of light. Even so, to go back any considerable distance in time, you need to be going a proportionate rate of speed. For instance, let's just say you want to go back 48 hours in time. You would have to go 48 times the speed of light to get there in one hour. You would need to go 17,856,000 miles per second to get to two days ago in a half hour. Maybe if the blackhole has actually stopped time within its boundaries, then accelerating the blackhole any degree will relult in a backwards movement through time. Again, the blackhole can only go as far back as it has lived. If you wanted to reach a specific destination in time, every single photon would have to be catalogued upon entering the blackhole, then traced backwards in order to reach a specific point in time.
it may be possible that all you need is the acceleration to move backwards, and having seen the past is not a prerequisite. But then the very thought of exactly how fast one needs to go remains an issue. If time truly were frozen within the blackhole, then it would be simple, any amount of acceleration bringing you into the past. I can theorize forever about what might happen, but the truth is, it will probably just break... which would still be cool as hell to see.
Sorry, I don't have any proposal for a time machine that is guaranteed to work, but these are the premises I'm working with, so if you can figure it out, let me know.
Astral Plane Theory
Unified Field Theory