I was recently pondering time travel and i have come up with a couple of issues that i can't find answers for. This isn't to suggest that time travel is possible nor impossible, merely to assume that if it was possible. My first query is that if i was to travel back in time would i remain in the same space or would the I move to remain in my original frame of reference. E.g. the earth is rotating around its axis and around the sun whilst the solar system rotates around the galactic core and so on, so if i jump back 1 minute the physical space i am in now would have been in space 1 minute ago. ( I hope that makes sense) My other thought was if time travels slower the closer to c. you get in reference to somebody on Earth, would that mean travelling slower than some one Earth mean that time would appear to move faster from the Earth's viewpoint? Wouldn't that then mean that in theory you could land back on Earth before you left? I understand the impractical nature of the latter and i am only talking hypothetically of course.
I remember a strip in 2000ad called Strontium Dog where he had some sort of time grenade that did essentially what you've described there. Moved people in time so when they reappeared they were in space.
Cool, I tried googling to see if this question had been answered somewhere but if it was i cannot find it in the plethora of ****ing contests that inevitably arise in the forums where this question would be asked. It kind of makes sense that is what would happen, although i suspect that sense has got bugger all to do with this field of science.
Although...aren't space and time actually space/time? And so a change in time might make a change in space too? I literally have no idea what I'm on about.
This is the dilemma i face every waking moment. If space and time are inexorably linked then that solves that problem; I am under the impression (illusion?) that that is only relevant re. special relativity. If i 'jumped' back though wouldn't i be outside of those laws as i am no longer occupying one reference but dissapearing from one and appearing in another. This is assuming one could just 'jump' through time rather than use some sort of appliance to alter time relative to your frame of reference. Oh i have no clue what is going on, I'm going to do a soduko; at least i know i fail those for a reason.
Theoretically you would remain in position in your original frame of reference. This would cause a few slight problems, given that the earth rotates at about 1 000 m.p.h., and circles the sun at roughly 66 000 m.p.h. Relative to local standard of rest the sun itself is moving through the galaxy at approximately 43 000 m.p.h. So, a time jump of 1 second into the past or future would move you approximately 30 miles from your starting position, relative to the earth, sun, galaxy etc. This actually violates relativity not simply by the time travel aspect, but by allowing you to determine an absolute frame of reference. Yes. Although it doesn't actually work quite like that. However it has been tested (among many other parts of relativity). http://en.wikipedia.org/wiki/Hafele%e2%80%93Keating_experiment Nope - because to do that you'd have to exceed c, and as far as we can tell from our current knowledge of the universe that is not possible (requiring infinite acceleration). Edit: Strontium Dog's time grenades caused a procession of ten minutes - which would put you 18 000 miles away - long swim to get back.
The only theoretical example of possible time travel I've read which I rate (or, perhaps fairer to say, which I understand), is that by traveling at an appreciable fraction of the speed of light away from a point, and then traveling at an appreciable fraction of the speed of light back towards the point, you would find that more time had passed at the point of origin then had been experienced by the traveler. So you could travel away from the earth and, after a fashion, arrive in the future (in that you would have aged less then the earth). If it were possible to create a stable, controllable, traversable wormhole, of which either end could be moved freely, then you could move one end of the wormhole away from said point in space in the same manner as described above, at which point the two ends of the wormhole would effectively be connected to different points in time, allowing for backwards and forwards time travel, although limited, and of course not to a point prior to the creation of said wormhole. In fact based on my understanding of it it would be impossible to travel as far back as the creation of said wormhole, the closest you could come would be to travel back to the point of creation + the travel time of the end which was moved away and back at relativistic velocity, if you jumped in as soon as it got back. If the process could be repeated then I imagine you could gradually increase the disparity between the two end by making a series of small movements, away and back to the point of origin, at relativistic velocity. If you were to do this with both ends, and obviously keep very close track of how far each had moved then I think it might be possible to gain some degree of control over the disparity between the two. This is based on my (extremely) limited understanding of theoretical physics.
Bugger, sorry, failed to answer the question. Ehm, if you had sufficient control over the wormhole to attempt this, then I imagine you would have sufficient control to determine the points in space at which you exited them. You couldn't return before you left, but you could return after you left, which sounds obvious actually. I mean you could return after the point at which you should have returned purely based on your experience of time during the journey.
Not an absolute frame but a relative frame, as from the calendars and clocks on Earth. Re. the jump of 1 second equals 30 miles of rotation, this is my query. Would that happen or is space and time so intertwined that the act of travelling back in time also mean travelling back in space too?
Conundrums aside, Id i could time travel, i'd gather 50 of myself, take all of them to the city center, and do a big flash mob dance of Gangam style =D
The original question reminded me of a Red Dwarf scene (a comedy-sci-fi show from early 90s) where they have found a time machine on their little shuttle while stuck million light years somewhere in space. So while in space they thought to go back a few hundred years to see what it was like. They switched it on, looked outside and they were still in space. The joke being...they have successfully traveled back in time...but still in the same place where they were
Nope, because you're only looking at the time aspect of it. So, let's say you jump in time, but don't change your position. That means that, for that tiny time jump, you have an absolute position. You can look at the movement of things around you during that time to extrapolate that, and give you the absolute reference frame of the universe - promptly breaking relativity. In fact I suppose that answers the question. If we were to assume time travel is possible (instantaneous time travel), but that in all other ways relativity is correct then a time jump would be somewhat quantum in nature - it'd have to be in order to preserve relativity. In other words, you could end up absolutely anywhere. Depends entirely on the time travel method. Are we talking along the lines of something like the TARDIS (which basically relies on magic), a wormhole (where obviously positional changes are involved), or a time jumping wristband with physics otherwise rigidly applied?
I thought that was General Relativity that said that all things have equal claim to absolute frame of reference and Special Relativity took things with in their own frame of reference or have i got them the wrong way round again. Assuming an actual instantaneous jump via magic wristband or a time machine observable travel as in the book. Would you remain in the actual space originally occupied or would your relative position on the Earth be maintained through the same mechanics. If a TARDIS is the vessel then it seems that OddsBods stable, variable wormhole is used.
Special relativity is a generalisation of Gallileo's principle of relativity - and general relativity is just a generalisation of special relativity. In both forms of relativity the rule basically boils down to 'there is no way to determine a special frame of reference'. That's where all of the relativity effects come from - if you could determine an absolute frame of reference then, theoretically, the effects of relativity as you approach c would vanish. All of the relativistic effects are based on the fact that as you approach the speed of light your personal reference time alters so that you always observe the speed of light in a vacuum as a constant. If there's a single, static point in the universe then the speed of light would not be a constant in all frames of reference. The machine in the book simply accelerated passage through time (they're very lucky that at no point did they end up over water) and so normal inertia would keep the machine in place on the earth's surface. In the case of an instantaneous jump (vanish and reappear) I'd imagine that you would end up in deep space, theoretically, as inertia would not be holding you in place during the transit. Of course, the instantaneous jump would also require relativity to be wrong in the first place, so being able to use it to determine an absolute frame of reference isn't so important.
I remember a lecture talking about if it were possible for you to stand on the edge of a black hole you would see the present and future. Raz
I think i grasp the relativity aspect and it makes sense to my silly human brain, in regard to your second point i assume the part about not ending up rather wet is regarding the changing of the land and sea over the eons (as in the Sahara was once an ocean floor) if the vehicle remains rooted to the spot by inertia. If that is the case why would inertia be relevant in speeding up time? I should presume that the vehicle somehow forms a bubble of stable time around itself that allows the user to safely traverse time without suffering the usual consequences of moving forward/backward in time, namely aging/Olay. Oh i get the inertia element now, Do'h. It would therefore mean that the acceleration would have to be gradual and stable to prevent the external force from dislodging the craft, this means that a sudden loss of power to your time accelerator would mean a very sudden long distance trip through space. No hand brake skids then. :evil: So the magic wristband would dump you in a vacuum if we follow the laws of physics as we know them, but there may be a way of using an artificial stable wormhole that is capable of being set to specific time/space co-ordinates? Some kind of quantum/11 dimension tomfoolery is needed me thinks. Virtual high five to a MAPper that can make me a stable artificial quantum multi dimensional worm hole. Take your time. :hat:
