ahh-- i see--you are such a genius, but yet, if the sentence does not have a capital--you cannot understand??--comical. Please Register or Log in to view the hidden image! (shrugs) ahh, more pathetic, comical, elementary minded, nonsense?
Definitely my fault, as I said. I saw the small letter starting the phrase, and assumed it was part of the previous sentence.
ahh-- i see--you are such a genius, but yet, if there is a period and then the new sentence does not have a capital--you cannot understand??--comical. hilarious (shakes head)--carry on.
I never claimed to be anything. But thanks for the compliment(s). What I think you meant was "Ah, I see where my writing may have caused you to make an honest mistake."
not directly--but then again, that is simply just this topic. overall-- whatever you need too tell yourself. Please Register or Log in to view the hidden image! (shakes head)--carry on.
except that is exactly not what i clearly typed--that is simply, and obviously, you attempting some sort of manipulation. Please Register or Log in to view the hidden image! (shrugs) again, Please Register or Log in to view the hidden image! (shakes head)--carry on.
The time travel I mention requires a toroidal black hole. Also not ruled out by GR, but pretty darned unlikely to find naturally. The links I've looked into seem to mostly be related to refuting this kind of travel, (with a a "cosmic censorship" hypothesis, which itself has little grounds for plausibility, except perhaps to make people feel better about time travel). This suggests that the toroidal BH hypothesis has been under discussion and had moved along. I'm going to have to look farther back to find the initial hypothesis if it interests the OP.
I don't think you can show time travel is allowed by GR (or any other scientific argument) because neither the future, nor the past, even exist now. Going to Peter Pan's Never Never Land, NNL, is also not forbidden by GR. That, like time travel, is impossible because it these destinations (NNL, Future & Past) do not now exist. Only the evolving "now" exists. More advanced technology, will not change this fact. You can not call a slowed rate of aging "time travel." The are several existing ways to live longer and let what is now a non-existing future become your "now." Exercise, regular medical check ups, proper diet will all on average do that, but they are not "time travel." Suspended animation and spending 30 of your years in a fast moving space ship, neither of which is impossible now, would not be time travel either - just slowed rate of aging compared to time lapse on earth's calendars. Many are using medial check ups, proper diet, and exercise to live longer. I. e. experience the world that will come into existence from the more distant future than if they did not do these common means of slowing their rate of aging. but they are not time travelers. Some day, a fat lazy slob, who will not do theses things, may be able to celebrate his birthday and New Year's eve of the year 200 years after he was born, via suspended animation. This not time travel. Some day a rich, but fatally sick man, may make a fast round trip thru space, and return 100 earth calendar years later, when medical science has found a cure for his fatal disease. This is not time travel. All these methods, some now even possible, are not time travel - they are slower rates of aging in comparison to people remaining on earth so your death date is after more earth calendar years have passed. Some day, if rich enough and technology has advanced, you might be able to experience the first 365 days of each new century on earth, before getting back into your space ship. This, getting to experience the changes each 100 years brings, is an interesting idea, not prohibited by GR, but also is not time travel SUMMARY: Time travel is impossible as the future (or past) you would travel to, like Never Never Land DOES NOT EXIST. This is not a technological limitation to over come; but yes, GR does permit you to live only one year on Earth at the start of each earth century for three or four millenniums. (Assuming that when you return to earth, in say earth calender year 2700, the population then on earth does not sterilize your space ship and all that is in it as a protection against ancient medical diseases, like the common cold, etc.) You confuse slower rate of aging, which is possible, with time travel, which is not possible. PS: To believe true time travel is possible, you must believe some where NOW a future we will evolve to already exists for you to travel to. I. e. that you could visit them and try out their tele-porter machine that exist on each street corner, as cars were abandoned 100s of years earlier. etc. That also requires you to believe you have a pre-determined future. No choices.
I apologize. I seem to have caused a few spats, which was not my intention. As I said, I'm not an expert by any stretch of the imagination but I am fascinated by time and my thought was inspired by a lecture in which the "time-telegraph" paradox was mentioned. I won't attempt to explain this paradox as you are all obviously far more knowledgeable about this subject than I. I honestly don't know whether time-travel into the past is possible or not - I can see there are arguments on both sides and it's plain that I have a lot of reading to do! My idea is that, if time-travel into the past is possible (a big If, I know), then there might be a way to do it without paradoxes. I'll try to explain it in a different way, if you'll indulge me a little more. Imagine a cricket ball, but in four dimensions instead of just three. In three dimensions, the ball is a sphere - in four, it's more like a wire, stretching back in time from its manufacture to the present (assumption). This cricket ball is a loose analogy for a particle we wish to send back in time (by whatever means). Imagine throwing the ball straight up into the air, this upward trajectory representing normal "forward motion" through time, and that the highest point of its trajectory is the point where we send it back in time and its downward trajectory represents the ball "traveling back" in time. In four dimensions, the ball going straight up cannot fall straight back down along the same trajectory because that spacetime already contains the ball/wire. Therefore, if we try to send the ball/particle back along the same route we cannot because it'll bang into itself. At this point, I imagine three possibilities: 1) the ball will become "stuck," balancing on the top of the "wire" and effectively disappear from normal spacetime. 2) The ball will bounce off itself, "falling" back down at an angle to the original trajectory. 3) The particle will smash itself apart, like two particles colliding in the LHC. However, if we throw the ball up at an angle, it will be able to fall back down but on a different vector, without banging into itself. That trajectory will naturally move further and further from the initial trajectory - similar to possibility 2 above. This would mean (in my mind at least) that the time-travelling particle will move further and further away from the initial trajectory the further back in time it goes. I suppose the time-travelling cricket ball will have a time-cone (analogous to a light cone), making it impossible to interact with itself in the past. For this idea to have any validity at all (and I'm not saying it does) the falling ball, or section of 4D "wire," must at each point in its trajectory have the original trajectory, or section of wire, forever outside it's time/light-cone. It's not my intention to claim that backwards travel through time is possible or impossible but that, if it is possible, paradoxes might be naturally impossible. Thanks, all, for your replies and for not treating me like the ill-informed idiot I suspect I might be...
" a system-to-another-system." and also, what are your choices,what are you choosing from? does this not imply an inventory of choices that are predetermined for one to choose from?
Is the past fixed, though? We only have our memories and records to go on, which are rarely 100% accurate and often disagree. Some things might be fixed, for example projecting the orbit of a planet back, but smaller things might be "fuzzy" and the further back one goes, the fuzzier things become. Even projecting planetary orbits back far enough would start to introduce minor uncertainties which might increase the further back we plot their motions. The future might be similarly fuzzy, with all possibilities available in that fuzz. Perhaps the only historical or future events which are "fixed" are those which have been comprehensively and precisely recorded or predicted, similar the collapsing wave-form in quantum mechanics?
again, " a system-to-another-system "--past(system), present(system),future(system). the physical state of an entity aspect is not the issue. the actual issue is simply the consciousness aspect.
Sure, there are time travel solutions for GR, but there may be other rules of physics that prevent these solutions from being realized and GR is likely not entirely correct.
That's not exactly what happens. The change of the coordinates is such that every path into the future goes toward the center of the black hole. Any evolution of the state of the system takes things closer to the center.
I'm not sure the present can be said to exist fully. The present lasts a very short time and by the time we've experienced it (given that it takes time for us to receive and process sense information), it's already in the past and the next set of stimuli, still on its way to us, is still in the future. The present, then, may also be "fuzzy."
Please Register or Log in to view the hidden image! No wucking furries. Time travel is a debatable subject that gets many roused up. And despite some of the irrelevant positions taken by those with the negative thoughts, many reputable physicists see it differently. I mean how would Columbus or Captain Cook view a Jumbo jet today! Or the fact that man has walked on the Moon! http://www.space.com/28000-physicist-kip-thorne-wildest-theories.html https://plus.maths.org/content/time-travel-allowed In brief: The laws of physics allow members of an exceedingly advanced civilisation to travel forward in time as fast as they might wish. Backward time travel is another matter; we do not know whether it is allowed by the laws of physics, and the answer is likely controlled by a set of physical laws that we do not yet understand at all well: the laws of quantum gravity. In order for humans to travel forward in time very rapidly, or backward (if allowed at all), we would need technology far far beyond anything we are capable of today. Travelling forward in time rapidly Albert Einstein's relativistic laws of physics tell us that time is "personal". If you and I move differently or are at different locations in a gravitational field, then the rate of flow of time that you experience (the rate that governs the ticking of any very good clock you carry with you and that governs the aging of your body) is different from the rate of time flow that I experience. (Einstein used the phrase "time is relative"; I prefer "time is personal".) more at link............... http://www.preposterousuniverse.com/blog/2009/05/14/rules-for-time-travelers/
Agreed.......But at this stage of our knowledge, we are able to conclude that any sufficiently advanced civilisation, [not withstanding any prohibitive laws of physics] could "time travel" in the manner explained in the links.
