A thought about time travel

[aTOMiC]

One of the arguments against the possibility of the existence of time-travel is that we in the present (or in the past for that matter) have no evidence that travelers from the future have ever visited. It occurs to me that there is a possibility beyond the contention that time travel is verifiably impossible or that there is some advanced agency charged with covering up the incursions into the past. Accepting that time travel is somehow possible; consider that in every instance of movement through time from the future to the past the timeline of the destination date is immediately altered upon contact, instantly creating a new and separate timeline from the original. This new timeline is the one that is affected and altered by the introduction of matter and movement from the future. This, our timeline, continues on unaffected accounting for the lack of proof from said time travel event. Further, this timeline would not accept time travel as a reality until the very day that it is invented. This theory also makes sending a cyborg killer back into time to kill the savior of mankind before he reaches manhood rather moot. In some identical reality said savior is terminated however the original timeline is completely unaffected.

Yes I have too much time on my hands….no pun intended.

[Demondime-a-dozen-spawn]

Even if it's possible, the biggest drawback to time travel into the past that I'm aware of (and one you rarely hear about), is the fact that every object in the Universe is in motion relative to every other object.

The space I occupy and the space the Earth occupies and the space the Sun occupies and the space the Galaxy occupies at any given moment will not be the same space that I, or the Earth, or the Sun, or the Galaxy occupied at any given moment in the past.

Were I to travel into the past, upon arriving, I would still occupy the same space as I occupied when I set out from the future, but the Earth, and the Sun, and the neighborhood of the Galaxy will not arrive at those spacial coordinates for however long my jaunt through time was.

So depending on the "length" of the jump, going into the past is really only a trip to the middle of nowhere, and to the vacuum of space at that.

[wayfriend]

aTOM,

The hole in your theory is that there is only one timeline where no one has ever yet time travelled, while there are many "branch" timelines where someone has gone back in time and said hello. So your question becomes, what are the odds that we're living in the original base timeline and not in a branch timeline?

Spawn:

The hole in your theory is that time-travel would not be using the frame of reference of the object moving back in time. According to the frame of reference of the object moving back in time, it is sitting still, and the universe is moving around it. Or not moving. Relative to you, the Earth is standing still, and not moving. So if you went back in time, the Earth would not have moved.

[Sorus]

aTOM,

The hole in your theory is that there is only one timeline where no one has ever yet time travelled, while there are many "branch" timelines where someone has gone back in time and said hello. So your question becomes, what are the odds that we're living in the original base timeline and not in a branch timeline?

My theory is that alternate universes are being created by every choice you make and everything you do or don't do. In some other reality I didn't reply to this post, and that created a branch timeline. Most branch timelines wouldn't be drastically different from the original. Out of the billions of branch timelines, the odds of living in one where time travel exists is very small. Be glad you live in a branch that has electricity and indoor plumbing.

If you want a visual, picture the Milky Way, with all the stars as branch timelines spiralling out from the base timeline.

[Demondime-a-dozen-spawn]

The hole in your theory is that time-travel would not be using the frame of reference of the object moving back in time. According to the frame of reference of the object moving back in time, it is sitting still, and the universe is moving around it. Or not moving.

Which is it? You can't have it both ways, H. G. Welles.

Relative to you, the Earth is standing still, and not moving. So if you went back in time, the Earth would not have moved.

Then, according to this, depending on whatever subjective length of time I actually spend traveling from the present to the past, and the "distance" (in hours or days or months or years or eons) between now and then, I have somehow kept pace with and covered the physical distance seperating where the Earth is "now" to where the Earth was "then," leading to the impossible conclusion that, not only have I traveled in time, but have exceeded the speed of light traveling in space too.

The actual hole in my theory, which I alluded to in the beginning of my first post, is that Time travel into the Past just ain't possible.

Of course, there's always Tipler's Rotating Cylinder of Extreme (but not infinite) Length, but that can't go into the past beyond the point it was/will be built. And even Tipler's theoretical machine, I believe, has been relegated to the rubbish pile by the latest advances in physics.

[CovenantJr]

Spawn:

The hole in your theory is that time-travel would not be using the frame of reference of the object moving back in time. According to the frame of reference of the object moving back in time, it is sitting still, and the universe is moving around it. Or not moving. Relative to you, the Earth is standing still, and not moving. So if you went back in time, the Earth would not have moved.

I don't follow what you're saying here. The earth seems stationary to me because I'm standing on its surface and being moved with it. If I pop myself back in time six months, I won't be standing on its surface. I'll only move with the earth, and thus reappear still on its surface, if I pass through every intervening moment, The Time Machine-style. If, however, you have it as a jump, as so much time travel fiction does, then as far as I can see I would indeed be languishing in the vacuum of space upon my arrival, as the earth wouldn't have been whirling me around with it.

Speaking of The Time Machine, I like that story's principle of time travel. We exist in four dimensions but only see slices of ourself. Like gravity, time tends to pull us in one direction, but just as the right science allows us to defy the pull of gravity and move upwards, so does the right science allow us to move 'up' time. Scientifically nonsense, no doubt, but an elegant idea I think.

[Loredoctor]

Spawn:

The hole in your theory is that time-travel would not be using the frame of reference of the object moving back in time. According to the frame of reference of the object moving back in time, it is sitting still, and the universe is moving around it. Or not moving. Relative to you, the Earth is standing still, and not moving. So if you went back in time, the Earth would not have moved.

I don't follow what you're saying here. The earth seems stationary to me because I'm standing on its surface and being moved with it. If I pop myself back in time six months, I won't be standing on its surface. I'll only move with the earth, and thus reappear still on its surface, if I pass through every intervening moment, The Time Machine-style. If, however, you have it as a jump, as so much time travel fiction does, then as far as I can see I would indeed be languishing in the vacuum of space upon my arrival, as the earth wouldn't have been whirling me around with it.

Speaking of The Time Machine, I like that story's principle of time travel. We exist in four dimensions but only see slices of ourself. Like gravity, time tends to pull us in one direction, but just as the right science allows us to defy the pull of gravity and move upwards, so does the right science allow us to move 'up' time. Scientifically nonsense, no doubt, but an elegant idea I think.

You are almost spot on, Covenant Jr. Wayfriend is discussing moving through time (although, it may be that there is a move through time with fixed space - which asks the question, fixed in regards to something). You discuss moving through time and space, only that the time traveler is selecting where he or she will be at each slice of time (so that the earth's orbit is the frame of space, and the time machine is positioned relative to something in that frame).

[Phantasm]

I was going to write a really long, thought out reply, but I'd already read the post next month.

[Krazy Kat]

I tend to be pulled towards the idea that the sun is the key referance point to a time-jump. Didn't the Star Trek Enterprise use the sun's gravitational field to return to Earth and save the whale!

Taking this a step closer to our reality, I've always fancied the idea that our solar system is the map to time travel. What if the planets have all been Earth at various stages of evolutionary development. Jupiter, Saturn, Neptune, Uranus are Earth's future. Venus and Mars and Mercury, are Earth's past. [please don't ask me to fill in the hole to that concept. Chemistry is way beyond me. And astrophysics]. Let's say we travel to Jupiter, using a Discovery:2001/HAL = type spaceship, Jupiter is still fixed in Earth time relative to the Sun's position. A craft therefore, is needed to take a differant direction to where Jupiter is in our future. Space Time Gravity should then become insignificant - no disorder effect to the timelines - the planets and the Sun are just too big for tiny humans to disturb.

David Cronenberg put forward an interesting notion in his film The Fly, that a machine is unreliable, and too dangerous. This I find the most fascinating of all when it comes to time travel. So let's assume time travel is and will be possible. What comes first, the time jump or teletransportation?

I'd like to read some of Michio Kaku books. I need more food for thought.

[dANdeLION]

Is there an alternate time line where this thread doesn't exist? Because if there is, I'm so there.

[Savor Dam]

No, Dan. By posting in this thread, you have effectively eliminated all the timelines you could have occupied where this thread did not exist. The only timelines now available to you are ones where this thread is present.

[dANdeLION]

Dammit, my alternate time-self was afraid this might happen.......

[wayfriend]

I don't follow what you're saying here. The earth seems stationary to me because I'm standing on its surface and being moved with it.

Correct.

But in another frame of reference, the frame of reference based on you, you are not moving. And the Earth, relative to you, isn't moving either. Because it is staying right next to you.

So, based on that frame of reference (which is as valid as any other), if you travel backward in time, the Earth will be there too. Since it's not moving.

At least, that's a theory one can make.

You may think it's unlikely to be true. But I consider it far more unlikely that there is a single, universal point of reference against which everything moves. A background grid, if you will.

If you think when you jump back (or forward) in time, the Earth will have moved out from under you, this means that you are using just that kind of background grid in your theory. That the Earth has an absolute position and speed in the universe. And that when you time travel, you remain in a fixed position against this background grid.

Of you believe Einstein, there is no background grid. Every frame of reference is as good as any other. So why not be able to pick which one to use when you time travel? And why not pick the most convenient one?

[Demondime-a-dozen-spawn]

I consider it far more unlikely that there is a single, universal point of reference against which everything moves. A background grid, if you will.

Yes, Einsteins relativity did displace Newton's absolute time and space, but I still say that traveling in time (by itself) is not going to cancel out/allow for the Sun's proper motion through the Galaxy or the Galaxy's proper motion through the Universe.

Middle of nowhere is where I say you'll time travel to.

[CovenantJr]

But in another frame of reference, the frame of reference based on you, you are not moving. And the Earth, relative to you, isn't moving either. Because it is staying right next to you.

So, based on that frame of reference (which is as valid as any other), if you travel backward in time, the Earth will be there too. Since it's not moving.

Pfft. On that basis I'd never be able to drive to the supermarket because, to me, my car isn't moving. But no; I do get to the supermarket and buy my much-needed nutritional goodies. Why? Because my car is moving, whether or not it looks that way from inside.

To put it another way: the earth doesn't seem to me to be rotating. That doesn't stop night falling.

[Demondime-a-dozen-spawn]

A very short hop back into the past of (say) hours would only put you at the Earth's core or a few thousand miles above its surface, depending on whether your starting point happened to be on the leading or trailing edge of Earth's orbit. Cold comfort, I know.

[Harbinger]

So traveling in time supposes that I cannot also travel to a very specific reference point? I have to physically stay where I began? That's no fun. We're discussing something that's impossible to begin with. Scotty beaming me up is more likely than me going back even 30 minutes to buy a lotto ticket.

[Demondime-a-dozen-spawn]

Some people have a naturally lower Suspension of Disbelief threshold.

Speaking of which, don't get me started on Star Trek style teleportation. Or any other style, for that matter.

Larry Niven, while he uses teleportation quite imaginatively, harnesses it with strict rules (and dire consequences if those rules are ignored) that placate stubborn asses like me.

[Loredoctor]

Of you believe Einstein, there is no background grid. Every frame of reference is as good as any other. So why not be able to pick which one to use when you time travel? And why not pick the most convenient one?

Actually, that is not strictly true. Einstein argued that there is no absolute space or absolute time. However, his theory states that there is absolute spacetime; that spacetime can be used as a frame of reference. He actually did not like the title 'relativity' and was going to refer to his system as Invariance theory.

[aTOMiC]

aTOM,

The hole in your theory is that there is only one timeline where no one has ever yet time travelled, while there are many "branch" timelines where someone has gone back in time and said hello. So your question becomes, what are the odds that we're living in the original base timeline and not in a branch timeline?

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