Time travel

waitedavid137

Honorable
Defining three more functions of the coordinates,
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The solution can now be expressed
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The metric tensor elements can be read off as the coefficients and the elements that we will need are
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To be continued...
All the metric tensor
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elements are independent of both
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and
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so in accordance with Noether's theorem, there are two Killing vectors we can use in solving for geodesic motion
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and
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where the list order is
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.
This yields as constants of geodesic motion
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and
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and with Einstein's summation convention and inserting the elements we get
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and
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These can be simultaneously solved down for either
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or
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. Doing so for the first yields the first order differential time travel equation for geodesic motion of
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QED
Its more mathy messy algebra to show, but the entire denominator of this is proportional to
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and it is that which yields the overall sign change between the two horizons. The horizons are the surfaces described by
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waitedavid137

Honorable
I'm not learned in science, but I just wanted to mention that any method of time travel will have to involve precise movement through space. This is because the earth and solar system don't stay in the same place over time. HG Wells style time travel misses this nuance. (Though he can be excused as he was a pioneer of the genre.) Legends of Tomorrow's Wave Rider gets it right.

Don't mind me; just piping in. :wink8:
Yes, what I did was derive exact time travel for precise movement through kerr-newman spacetime. In this method of time travel you find an old rotating or charged black hole and fall through it to the time that you want to come out. I have played with an HG wells style time machine as well which is a bit different, but if there is interest I can revisit that.
 
right now I'm playing with electromagnetic and gravitational radiation, this looks like it might go somewhere interesting
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I'm trying to understand what you're seeing here that has you intrigued, and it looks like this can lead to negative values for ds^2 ... which would make sense given the title of this thread. I assume that u = 1/r. What's k? And what's the relationship between EM and gravitational radiation, and time travel, that you seem to be discussing here? I've never heard of a relationship between either type of radiation and time modulation before. If you could create a standing gravitational wave, that might raise some interesting possibilities...but I've never encountered any discussion of such a thing because gravitational waves don't reflect off of anything afaik.
 
Honestly it worries me to think that time travel into the past might be technologically feasible. Because if it is, then most technological civilizations in the universe - which are probably 2-3 billion years ahead of us according to current astrophysical estimates of the ages of worlds similar to our own - would already have that technology. Which could explain a lot actually. And it would mean that we're so radically outmatched in capabilities (and even our thinking processes about time) that we'd be less sophisticated than a helpless drooling newborn compared to the civilizations visiting our planet on occasion. I mean seriously - what hope would we have to discover anything at all of significance about our interstellar visitors, if they could just go back in time whenever some outcome didn't serve their agenda, and change it?
 

Dejan Corovic

As above, so bellow
Honestly it worries me to think that time travel into the past might be technologically feasible. Because if it is, then most technological civilizations in the universe - which are probably 2-3 billion years ahead of us according to current astrophysical estimates of the ages of worlds similar to our own - would already have that technology. Which could explain a lot actually? And it would mean that we're so radically outmatched in capabilities (and even our thinking processes about time) that we'd be less sophisticated than a helpless drooling newborn compared to the civilizations visiting our planet on occasion. I mean seriously - what hope would we have to discover anything at all of significance about our interstellar visitors, if they could just go back in time whenever some outcome didn't serve their agenda and change it?

Somebody somewhere suggested that one can go back in time and change events, but he would go back along a different timeline to the one on which moved forward. So effectively he would end up in another universe, so the original universe would stay unchanged.

@Thomas R. Morrison if David can't translate that equation into plain English, maybe you can have a try?
 

waitedavid137

Honorable
I'm trying to understand what you're seeing here that has you intrigued, and it looks like this can lead to negative values for ds^2 ... which would make sense given the title of this thread. I assume that u = 1/r. What's k? And what's the relationship between EM and gravitational radiation, and time travel, that you seem to be discussing here? I've never heard of a relationship between either type of radiation and time modulation before. If you could create a standing gravitational wave, that might raise some interesting possibilities...but I've never encountered any discussion of such a thing because gravitational waves don't reflect off of anything afaik.
It may be better if I start a new thread so that topics don't conflate.
 

Rick Hunter

Celestial
Here's what I am wondering: is it possible to go back in time and see or experience it, without changing the past? All my life I have had a feeling that the past still exists in some fashion and can be observed, if we only knew how.
 

waitedavid137

Honorable
Here's what I am wondering: is it possible to go back in time and see or experience it, without changing the past? All my life I have had a feeling that the past still exists in some fashion and can be observed, if we only knew how.
Observation even from our time can perturb past experimental results. Look up quantum eraser experiments.
 

The shadow

The shadow knows!
I thought it might be of interest to derive the first order differential equation for time travel for geodesic motion through a charged nonrotating black hole. Though physically realistic black holes in nature will be of little if any charge, but of extreme spin, the result and math is far more messy but gives similar results to that of a charged nonrotating hole, and its worked out most simply the same way, so this will be the case of a charged but nonrotating hole. No black hole in nature will be Schwarzschild. They will be Kerr like and any radiative aspect will be Vaidya like. As such dump anything you ever worried about from Susskind and Hawking. Neither ever once ever mention Vaidya, because they didn't understand what he did, and because he utterly undermines their publications. Anyway, the nonrotating but charged hole, Reissner-Nordström, solution is
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Now the metric elements read off the elements of the coordinate differentials here are all independent of time. Now I know no one here, and hardly any physicists, knows Noether's first name for the same reason that they don't know Vaidya's but do know Einstein and Hawking's first names, so look it up if you feel the need, but anyway in accordance with her theorem that means there is a timelike Killing vector
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for that isometry in the metric yielding as a constant of the geodesic motion of
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Here
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is merely what I name that constant where this
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is often called the conserved energy parameter of geodesic motion. In the case that it is far enough from the hole to neglect the mass and charge terms, it is equal to the
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of special relativity. Since the metric is diagonal there is only one element corresponding to the nonzero element of that Killing vector that contributes to the sum
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Which results in
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simplified
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QED
I let my 17 year old daughter see this she wrote this:
so they don't tell you what the r and c, most likely its resistance or capacitance. but the lower the r or c variable is the less geodesic motion and the higher it is the more motion that is detected
 
Here's what I am wondering: is it possible to go back in time and see or experience it, without changing the past? All my life I have had a feeling that the past still exists in some fashion and can be observed, if we only knew how.
An obvious but germane point that we could consider here is simply the case of light emanating from an occurrence: with a sufficiently large telescope placed at a considerable distance from that occurrence, it can be observed at future times. So for example, a sufficiently large telescope at the Alpha/Proxima Centauri system could be observing events that transpired here on the Earth over four years ago. The information is out there, radiating away from us at the speed of light - and that's true of all places in the universe other than positions within black holes. There are more mundane examples, like our observations of the Moon and the Sun for example; when we look at the Moon we're seeing it as it was about 1.3 seconds in the past, and when we look at the Sun we're seeing it as it was about 8.3 minutes ago. When we look at the cosmic microwave background (CMB) radiation, we're actually seeing a very red-shifted image of the surface of last scattering, when the universe became transparent to light about 379,000 years after the Big Bang.

On the more esoteric side of things, there's a myth about a device invented by Father François Brune and Pellegrino Ernetti called the Chronovisor, which was said to somehow reconstruct the photon and phonon signals from past events so that the past could be seen and heard. This would seem to require a reversal of entropy, but it's fun to think about.
 

The shadow

The shadow knows!
then they simplify it by moving the derivative to the left
sorry I Hit send to quick. let me know if this is of relivace to the discussion.
 
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