A practical obstacle to a 'Time Machine' (Nothing to do with some kind of Paradox)

Dear Mods, I'm not sure if this is the appropriate place for this post, so please feel free to move it...

I just recently came across a very simple obstacle to terrestrial time travel. I came across it in a webcomic of all places and it seemed so simple I was surprised to have never thought of it or seen it mentioned here.

Note, this is not an issue with speed of light travel, wormholes etc but more specifically with traditional ideas of a terrestrial 'time machine'.

It seems to me your travel forward/backward in time would be relative to the universe as a whole and not the planet. So therefore unless you calculated your arrival date to one where the planet was in the exact same position in its travel around the sun (and the solar system in the same position in the galaxy, and the galxy in the same position etc, etc, ad infinitum) then you would most likely arrive in the middle of empty space or, best case scenario, even somewhere in the middle of the Pacific ocean (And if your travel started in say, Denver, your arrival in the Pacific would be preceded by a one mile fall).

Now I suppose this could be overcome if your travel was tied to the location of some sort of pre-existing "Gate" or "Gates" that you would travel between, but this would lead to the necessity of making sure the gates still existed and were active (by whatever means) at the exact time you wished to arrive. This would also mean travel back in time would be limited to a time after the original gate was built.

I guess some people could say that you could 'lock' yourself to the earth's magnetic field or some such, but it still seems like a very real obstacle to consider...

Thoughts?

Here is the original comic that got my mind working...

You are constantly, over time, being pulled toward the center of the earth.

reply to post by RestingInPieces


This still doesn't prevent the other, more mundane, "middle of the pacific ocean" problem though.

Originally posted by USAFJetTech
reply to post by RestingInPieces

 

This still doesn't prevent the other, more mundane, "middle of the pacific ocean" problem though.

I have news for you. When you jump up, the earth doesn't rotate under you with you landing in a different spot.

reply to post by RestingInPieces



Actually, it does.


Fortunately, you are moving at the same speed, and in the same direction as the Earth when you jump; You share the planet's momentum. The duration of your separation from the planet results in so little loss of momentum that you appear to land in the same spot that you jumped from.


Like all objects, however, your jump actully describes a ballistic arc.

Yes, but this is assuming that normal laws of gravity apply while traveling through time. I know just recently a thread was posted here about the interaction of gravity and bending light and space time as a possible mode of time travel... if we can reasonably assume that time travel would involve bending (if not breaking all together) accepted rulesof physics, why should gravity remain a constant?

reply to post by Bhadhidar


Very good point... how would a potential time jump effect that momentum? If its something as simple as slowing the subject down while everything else speeds up (a gross oversimplification I know, but thats how its always portrayed) then I imagine your momentum and that of the planet would have their relative similarities skewed

This has already been suggested.

reply to post by Gentill Abdulla


I didnt know that, I searched ATS threads before posting this one but I guess I must have missed it

[end thread]

reply to post by USAFJetTech


Well USAFJettech (funny user ID btw), good point, but the biggest problem with time travel is even simpler than this, and it is of a purely philosophical nature.

It's the fact that "time" is only a conception, just as our whole chronological, linear conception of how things evolve and move in this world. The idea that there is the past, the present and the future is purely, literally, an idea, and nothing more. Yet our whole civilization has mostly adjusted and synchronized itself to it so it everybody could be coordinated and everything would hold together, at least from the exterior.

But in reality, if you just look around you and place yourself our of the idea of time, all you actually see are things moving, relatively, and evolving. You cannot see a past, nor a future, and not even a present, you only see a constant FLOW of things. Time was only a way to measure this flow so that we would not lose our faint grasp on reality, and between humans beforehand. Solar, mechanical or electronic clocks made it possible for this measure to work on a large scale so that a broader mass of people could relate to it, just as compasses or rulers. This measure, like the metric or imperial systems, are strictly cultural constructs, and the best proof is that American Natives did not have any notion of time in their ways to measure the world, it was brought to them, just as the imperial system and the English language was brought to all British colonies so now today we get to communicate mostly in a language that's foreign to many people around the world, so that it makes it possible for folks like me to bring my ideas on ATS (!).

Sooo, since the relation between the abstract idea of time and the concrete referring reality is still totally unfounded, how could there be a way to make a machine reverse a process that exists only in the world of ideas? It's illogical. Doesn't make more sense than making a table levitate with your mind. The scientists who believe that are idiots that can't think outside the box at all...

Perhaps we can "go back in time" to some extent -by going back to some other order of things- but there would be no way, with our current system of measure, to do that. Quantum physics has offered some interesting clues to it, but still we have to find a proper system of measurement to use. If you wanna go back in time, you just simply don't enter, like, "September 18th 1856, 1:46 pm, 23784 seconds" in the time machine, so that you can go save your great-great-grandfather from being shot by a gunslinger. It simply won't do anything. We need a system that has a minimum of relation with the real, physical world, like carbon-dating, or astral configurations, or something.. but would it coincide with our own notion of time? Most probably not, as reality is far from being linear and continuous. It is, actually, very multidimensional in the way it evolves, and goes far beyond what we can perceive and measure.

Originally posted by Bhadhidar
reply to post by RestingInPieces

 

Actually, it does.


Fortunately, you are moving at the same speed, and in the same direction as the Earth when you jump; You share the planet's momentum. The duration of your separation from the planet results in so little loss of momentum that you appear to land in the same spot that you jumped from.


Like all objects, however, your jump actully describes a ballistic arc.

You're completely wrong. Every time I jump up, I hit the walls of my house! Also, since I'm traveling forward in time at 1 second per second I'm constantly moving closer to the wall!

Anyway, I think you missed the point. The point was that the time machine will obey conservation of momentum just like a jumping person will. In the time machines case, it's conserving all of the momentum. It is not being "slid off the side of the earth" or "toward the wall of the room" or however anyone wants to think about it.

The idea that a time machine would end up in a different place suggests that the universe as absolute locations and that the time machine could occupy an absolute location, while everything else kept moving. I'll assume you know why.

Luckily for our time machine, it is bound to spacetime.

Yes, but this is assuming that normal laws of gravity apply while traveling through time.

You're going to have to disprove relativity if you want to argue that.

Are you guys debating a Star Trek Episode?
You must be because you seem to speaking with such certainty about a technology that does not even exist.

Let me put it another way. There are no experts on time travel and the intricacies involved. The Op brought up an excellent point that most people who fantasize about time travel fail to consider.

Originally posted by Sparky63
Are you guys debating a Star Trek Episode?
You must be because you seem to speaking with such certainty about a technology that does not even exist.

Let me put it another way. There are no experts on time travel and the intricacies involved. The Op brought up an excellent point that most people who fantasize about time travel fail to consider.

I don't think it's an excellent point at all. It's a point that has been discussed so much that it's actually found in a comic.

I think what most who fantasize bout time travel fail to consider is that time "passes" differently depending on where you are in the universe, depending upon gravitational fields. It also "passes" differently depending on how fast you are moving.

You could very well travel to the future on one side of the universe and still end up in the same time period of someone who is just moving faster by the properties of their region of space.

So who's in the future, then?

THE ANSWER IS NOBODY. THERE IS NO TIME-TRAVEL.

THERE IS ONLY SPACE-TIME TRAVEL.

Imagine there are 4 quadrants in the universe.

quadrant 1: Earth
quadrant 2: super-massive black hole
quadrant 3: ship going light speed
quadrant 4: time machine

Time will go by at different rates for each of these objects, depending on the perspective that each one is viewed. In fact, they are all time-machines because they are all moving through space-time at different rates.

reply to post by USAFJetTech


hi there,

thanks for posting this.

great link and i like your thoughts and musings on the subject.

thanks

snoopyuk