Lets see if we have any "nerds" here... Time travel question.

[AZCoolerBrewer]

Let me explain why I believe effective time travel is impossible.

If you were to go forward or backwards in time, to what spatial reference would you travel.? In other words, if you go back in time from this position of the earth in space, where was the earth at that time? In the middle of space someplace, right? So you go back to the time/place where the earth was--which means you're dead, dead, dead.

At any moment we're flying through space, the sum total of a lot of velocity vectors--the earth is spinning, it's revolving around the sun, the sun is moving around the galaxy, the galaxy is moving in relation to other bodies.

So to plausibly move in time, you'd have to account for not only place but also time and velocity vectors. And since there is no absolute location to serve as a reference for any of that....

In other words, you'd have to travel in time AND space if you wanted to go back or forward to any particular location on the earth or anywhere else. In fact, if you could do that, you'd have effectively a Star-Trek transporter. And that is why I don't believe effective time travel will ever be possible, even if time travel becomes so.

That's me getting my nerd on.

“Effective” time travel at least into the future is super simple and probably requires the least futuristic technology through suspended animation like Buck Rodgers. Going back in time however would be more difficult although consider suspending our galaxy right when a colony ship leaves to another galaxy, then they could come back and visit earth thousands of years in the past. One issue for any type of suspended animation is that as things go on around what is in statsis preservation is key to have the time travel work.

 

[BobBailey]

You exist and thus you simply do not prevent your own existence.

There is no chain of events where that could occur, hence the term "paradox".


I'm guessing you only watch and/or read non-fiction

You would be correct about my reading. As for watching, I do very little TV and even fewer movies. I'm 70 years old and have seen so many things that were considered science fiction become reality. Most of them were feasible, so not too surprising. At this point in time, I really have no need to ponder things unless they are grounded in reality. If time travel were possible, I feel secure that it would have happened by now.

To each their own. I have no problem with anyone entertaining themselves in whatever manner they choose. After all, that's what I'm doing right now Gotcha!!

 

[grampamark]

The answer is 42.

 

[Pkrd]

Have you seen Looper?

Go see Looper.

 

[Michael_Calgary]

Why waste your time even thinking about such an absurd fantasy? Why assume that your premises are true? $hit, I'm retired and don't have time to waste. Maybe you need to find a hobby

lol! Well I have "one" hobby that leads to the next. I brew beer... I drink it. Then I think about stupid stuff like time travel. hehe. Actually I was watching a science show (Nova) and it had a bit about time travel. The scenario they played out made me think of the topic of this post. I figure, If I'm thinking about it, somebody else surely is too!

 

[dmtaylor]

Time travel is possible, but only in the forward direction, never backward. Hence, the OP's scenario requires zero logical consideration.

Best way to travel forward in time is to accelerate in a spaceship close to the speed of light for several months or years, then turn around and come home. When you finally get back, everyone and everything you knew will be much older or dead.

Relativity. Cheers.

 

[mongoose33]

I imagine that if a device could transport you directly to a specified moment in time, then it could transport you through space to a particular location as well and make the necessary calculations to do so. If I'm not mistaken, the universe does have a center, which could be used an absolute reference. I'd think relative location could be used as well.
In Travelers they specifically reference using a T.E.L.L. and presumably some calculation as to the location and orientation of the Earth.

Well, we can imagine anything, I suppose. And maybe the universe does have a center, but I'll bet you'd have trouble nailing that down to inside a few light years...which means, there we are. No way to do it.

 

[mongoose33]

“Effective” time travel at least into the future is super simple and probably requires the least futuristic technology through suspended animation like Buck Rodgers. Going back in time however would be more difficult although consider suspending our galaxy right when a colony ship leaves to another galaxy, then they could come back and visit earth thousands of years in the past. One issue for any type of suspended animation is that as things go on around what is in statsis preservation is key to have the time travel work.

Suspended animation is time travel? I don't think so. It's sleeping.

Do I travel through time during the interval from when I drop off to sleep to when I awake? No. I sleep.

Now, I suppose you could call that "time travel" if you want. But IMO, it's not.

 

[mcgimpkins]

Didn't Jean Claude Van Dam already solve this?

 

[divrack]

If time is relative why don't I ever get presents from it for my birthday?
Maybe because time makes fools of us all.
Of course assuming a possible time machine is the easy part. Much harder is defining what the I is and how consciousness is manifested. In this scenario we would have to assume that self is a manifestation of the brain processinng change and so I don't think there's any real problem. Any time travel would necessitate the splitting of the person, but also the splitting of the universe, although probably only really feasible in an infinitely branching infinity of universes.. but I don't think that is an outrageous proposition. I think infinite infinity is easier to countenance than a limited and specific universe.

 

[GilaMinumBeer]

The answer to your question is always 42.

 

[RPh_Guy]

Best way to travel forward in time is to accelerate in a spaceship close to the speed of light for several months or years, then turn around and come home. When you finally get back, everyone and everything you knew will be much older or dead.

Relativity. Cheers.

Sci-fi aside, this is true (theoretically).

@Pkrd Looper's resolution is a time travel paradox :/
Sci-fi likes to take a view that time is not fixed (future is always in motion). Once you throw time travel as a possibility into the mix, then the past and present become constantly in motion as well (e.g. DC's Legends of Tomorrow, Travelers, Back to the Future, etc). This creates a constant flow of paradoxical events that the writers either ignore (most often) or simply call "time remnants" (Flash & Legends).
In this scenario, who's to say when past, present, or future reality become set?

BTW my favorite movie on theme is Paycheck, without giving away any spoilers.

Well, we can imagine anything, I suppose. And maybe the universe does have a center, but I'll bet you'd have trouble nailing that down to inside a few light years...which means, there we are. No way to do it.

I'm not sure you're giving scientists and futuristic AI enough credit
Do you know how scientists discovered the Earth was round? (Hint: it wasn't by traveling around it.) ...Way before the technological era.

Even if we couldn't calculate absolute position, we could guess and check by sending beacons back in time a couple seconds and make extrapolations. Or simply combine the time travel device with teleportation because why not.

 

[cloudybrewer]

Or simply combine the time travel device with teleportation because why no

Because "The Fly." That's why not.

 

[ancientmariner52]

Time travel is not only possible, so far it is unavoidable. The trick would be stopping it, reversing it, slowing it down. As far as meeting your future or past self.... I dunno. It makes my head hurt to think about it.

 

[mongoose33]

Even if we couldn't calculate absolute position, we could guess

OK. You go first. If you're ok with guessing.

and check by sending beacons back in time a couple seconds and make extrapolations. Or simply combine the time travel device with teleportation because why not.

Help me with something. If this is so easy, why don't we already have it?

 

[S-Met]

Using the provided model, there would not be a future self to meet. Since version 1 did not die, there would not be a version 2.

Version one went to the future to heal where version 1 did not exist. Going back in time to continue life, V1 didn't die thus cannot meet V2.

 

[AZCoolerBrewer]

Suspended animation is time travel? I don't think so. It's sleeping.

Do I travel through time during the interval from when I drop off to sleep to when I awake? No. I sleep.

Now, I suppose you could call that "time travel" if you want. But IMO, it's not.

Suspended animation is clearly not sleeping. A sleeping person would age over the years which is not part of a definition that describes suspended animation. The only difference between SA and using some sort of machine is that there would be a body laying around for however many years. Not very elegant, but definitely achieves the same goal as traditional (future) time travel conventions and a hell of a lot more realistic, if not as much fun to think about.

 

[mongoose33]

Suspended animation is clearly not sleeping. A sleeping person would age over the years which is not part of a definition that describes suspended animation. The only difference between SA and using some sort of machine is that there would be a body laying around for however many years. Not very elegant, but definitely achieves the same goal as traditional (future) time travel conventions and a hell of a lot more realistic, if not as much fun to think about.

It's sleeping. Slow sleeping, but sleeping nonetheless.

 

[ancientmariner52]

Suspended animation is clearly not sleeping. A sleeping person would age over the years which is not part of a definition that describes suspended animation. The only difference between SA and using some sort of machine is that there would be a body laying around for however many years. Not very elegant, but definitely achieves the same goal as traditional (future) time travel conventions and a hell of a lot more realistic, if not as much fun to think about.

Heinlein's The Door Into Summer. Cold sleep to go forward, time machine to go back. Not very realistic, but a fun idea. Looks at the economics of time travel as well.

 

[cmac62]

If I do travel in time how much baggage do I get to bring? Do they charge extra if I go over weight? Damn ripoffs.

 

[AZCoolerBrewer]

If I do travel in time how much baggage do I get to bring? Do they charge extra if I go over weight? Damn ripoffs.

Obviously you have to go naked, haven’t you seen terminator?

 

[Pkrd]

If I do travel in time how much baggage do I get to bring? Do they charge extra if I go over weight? Damn ripoffs.

And the TSA keep changing their rules. What if you end up in a time where an easily converted to a shank toothbrush is considered a terrorist threat? Do you go to future jail?

 

[JohnSand]

If I met my younger self I'd punch him for all the crap he put me through.

 

[RPh_Guy]

OK. You go first. If you're ok with guessing.

You missed the part where I said beacons? Inanimate objects sent into past/future could quickly determine absolute position scientifically. and don't create a paradox.

 

[afro_lou]

The only way bi-directional time travel would be possible would be through wormhole travel. Specifically, through man-made wormhole travel.
Relativistic time travel is definitely possible (and actually in effect right now! Just look at gps satellite corrections), but it necessitates a single timeline view. i.e. you can travel far, far into the future, but you are still you in your timeline and everyone else travels in the same timeline as well. By approaching the speed of light, or by approaching a vastly massive gravitational object (and basically achieving the same thing, time dilation), you affect your timeline by slowing the passage of time for yourself, but not for anyone else. So you can travel into the future, but not travel back. Also, because of this, you “in the future” are you in the present. So if you travel 100 earth years (or a thousand! It doesn’t matter) into the future by accelerating to nearly the speed of light, your timeline would be perceived by everyone on earth to have been you rocketing away and slowly slowing down to a near complete stop until 100 years in the future when you suddenly accelerated back towards earth. Weird, I know. The other problem is, you can’t travel back in time via relativistic time travel. It’s a one-way street.
That’s where quantum theory comes into play. Since quantum tunneling is theoretically (and measurably!) possible, that opens up a myriad possibilities for time travel both forward and backward. But! It also necessitates a multiverse view of the cosmos. Basically, to time travel to any point in your timeline, you have to find the alternate universe where whatever possibility you want to happen has happened, then travel (most likely via wormhole) to that universe. Once you arrive, there must be some sort of reconciliation or balancing to account for the extra matter in that universe and the lack of your matter in the previous universe. I suppose one of “you” must be destroyed, but how that is determined is beyond me... there’s your paradox! Or maybe it just doesn’t matter to the universe and you can go along and meet yourself in the “alternate” universe and just basically blow your own mind. Or, maybe you just find a universe where you died long ago and you live your own life in the far future of that version of yourself’s universe...

It gets confusing, I guess...

But travel to the past would have to happen through wormhole travel, which would still take more energy than we as a species could create in all our time in this universe, so that kind of precludes it as a possibility... and anyway, you could only theoretically travel to a past that your timeline has already experienced, so it probably wouldn’t be all that helpful anyway.

And anyway, as someone much smarter than I said, if time travel were possible, why haven’t we seen any future tourists yet? Someone would have had to travelled to our time by now.

 

[RPh_Guy]

you could only theoretically travel to a past that your timeline has already experienced, so it probably wouldn’t be all that helpful anyway.

That's basically what I've been saying.
Even once you get past all the logistics.

 

[afro_lou]

That's basically what I've been saying.
Even once you get past all the logistics.

Oh, you totally did! I guess I didn’t have “time” to read all of the posts before I posted. If only there was some way I could go back in time and edit my post! [emoji1]

 

[AZCoolerBrewer]

And anyway, as someone much smarter than I said, if time travel were possible, why haven’t we seen any future tourists yet? Someone would have had to travelled to our time by now.

It could be that time travel is fairly rare and because the multiverse is so huge, time travelers are all over the place, but our little corner is like a clearing in the Amazon where a person could live their whole life given that their needs were somehow met without ever seeing another human being. It would then be reasonable to say, “if there were others like me, surely someone would have come along by now.

Further it is quite possible that we will render ourselves extinct before we learn to time travel and if the other beings in the universe are anything like us, then they will be so focused on their own history and future that our little blip in history will be quite uninteresting or perhaps interesting in an academic sense.

Another explanation is once we’ve lived our history then it is set and a time traveler could wander all over the past checking things out, interacting with people and the very act of leaving to his/her own time erases anything that happened there.

I believe in science, so only what is possible is possible. To me the reason time travel isn’t possible is because it isn’t possible. So until it is done, speculating how it will be done is fun and perhaps an exercise in hope for exploration. I believe though that time travel will be much less sexy than the discussions we are having here. If you ask, “what is my purpose for time travel?” Then much simpler mechanisms can be devised that would do the job, but not be the real deal, like the Rip Van Winkle example I gave earlier, or a holodeck that would model a time with uncanny accuracy. I mean if you want to go back to December 8, 1981, you can watch season 6 episode 10 of Three’s Company “The Dates of Wrath” and really get a piece of what was happening all over the U.S. on that day. Sure there are many things that are different about watching the re-run then being there and watching it for the first time, but then our own perception of personal experience is so flawed anyway that we would probably see the past better in some ways watching it now then those of us who lived it back then would have seen it.

Anyway, quantum tunneling may be what gets us there, but my guess is that we have something else to learn that will make it more realistic for us to time travel and even then we’ll be able to do it THIS way but not THAT way. Like you can fly to Paris but not to the moon until you build a lunar mission vehicle and then you can go to the moon, but not mars, kind of a thing.

 

[gratus fermentatio]

Time travel as scifi likes to present it, relies on the supposition that the past, present & future exist simultaneously. If this is so, then travel in any direction (forward or back) in time (outside the current time-flow) would cause alternate realities to crop up, which would (theoretically) require some place for those realities to exist, outside our own current reality; or it might cancel out our own current reality in favor of the new reality. So if V.1 went fwd, got cured, thereby creating an alternate reality & went back (to a point say, 10 sec after he left), creating another alternate reality, which would alter his future reality, his previous reality no longer exists, even though it may be very, very similar. BOTH futures have been altered, and a sort of time loop has been created, though if both futures have been altered, the time loop isn't stable, going from alternate, to alternate, to alternate over & over, thereby further altering each reality...
Much like making a copy of a copy of a copy of a copy. (Back to the Future Pt.2)

Now if past, present & future do exist simultaneously, why can't alternate realities also exist simultaneously? How would a time machine/ship differentiate (if it could) between realities? Nov. 5th, 1955 may exist in multiple realities, each reality requiring some place to exist, separate from all other versions. (Time Cop) If every instance of time travel creates an alternate reality, and each reality exists without cancelling out the others, then how to tell one Nov. 5th, 1955 from the other, AND, how to travel between the different Nov. 5th, 1955's? You would also need the ability to calculate & move interdimensionally, though I'm not sure that's the proper term.

Now if past, present & future do not exist simultaneously, time travel would not be possible. The future isn't there yet & the past would be altered by your presence, thereby altering the current timeline. So even if you could travel to the past, you could only travel forward from there, to the point when you left. OR, perhaps you wouldn't be able to go forward at all, as that future timeline hasn't happened yet. So you might end up stuck in 1955 & have to live through that now altered timeline.

Even if time travel can be simplified to scifi models, you have to deal with the Butterfly Effect. V.1 gets cured, but to do so, the Dr. had to schedule the following surgery later in the day, causing that patient a longer stay in hospital, causing a larger bill, which causes there to be no Christmas presents for that family's kids that year, which causes 1 of those kids to steal a toy & get caught, going to jail, etc... (The Butterfly Effect)
Each seemingly insignificant alteration in the timeline could effect many other things, which in turn effect many other things. And the greater the time-distance, the more things will be effected & the greater the difference in the timeline will be. (A Sound of Thunder)

So, if you're writing a scifi story or making a movie, then yes, V.2 could see the arrival of V.1; why not? Time travel stories are fun to read/watch, and pretty much any theoretical problem presents a new & interesting twist to the story; anything too twisty can easily fairly easily be explained away, at least to the satisfaction of most readers. So ya, why not?
Regards, GF.