a question of time

[YT2095]

I`m putting this in here as it involves backwards time travel and since that`s still in the realms of Science Fiction I think it`s best in here for now

 

the year is 2090 and time travel is available. as an experiment a man is sent back to put a letter into a safe box and return to 2090.

 

how far he goes back in time doesn`t really matter lets say he went back 10 years.

it takes him 20 mins to put the letter in the safe box when he gets to 2080.

the people in 2090 are at this safe box watching it`s contents for this letter to appear at the same time they send this guy back to drop the letter into it.

 

now, will the letter appear in 20 mins time or the very instant then man goes back 10 years?

 

will the 2 times be running side by side minute for minute just 10 years apart, and so the letter apears 20 mins later as the man in 2080 drops it in?

 

would the letter always have been there?

 

does it apear the second he leaves the future?

 

 

any ideas?

[Sayonara]

Maybe it won't appear at all.

 

Assuming they're in the same timeline however, I'd bet it would appear the instant he left. There's no good reason why he can't arrive back then as well.

[YT2095]

I see what you`re getting at, a bit like this: this is a time line

____o_____ so he can do his 20 min loop and arrive back at almost the same instant he left?

but assuming that isn`t the case and the trip is one way, would it take 20 mins then?

I wonder because if it occured that instant, what if he went back and for some reason couldn`t put in the letter or it took longer than 20 mins. at what point of Instant does it become a reality that the letter will appear or not?

[Pinch Paxton]

If it were possible to go back in time, and then put the letter in the box there would have to be an explenation for this to be feasible. The only explenation that makes any sense is the alternate universe, the multi-dimension theory. This would mean that the man enters the time machine, and never comes back to the same dimension. So to his original dimension he must have died or something. He looks for the box 10 years back in time, but it is not there because he is in the wrong dimension, and never existed to try the experiment. He puts the letter in a bank vault instead. He returns to the future in yet another dimension, the people are not waiting for him, but he finds them, and tells them that the box was not there, and tells them about the bank vault. They go to the bank, but there is no letter there because he is in yet another dimension, and never existed here either. So basically, I say that he only exists in each dimension, as he arrives there. This is to account for the increase in energy that is required to sustain each of his lives. This way, there is no increase in energy. But I don't actually believe that any of this is possible. We could not interact with the past, although we might be able to view the past as a ghostly image.

 

Pincho.

[Pinch Paxton]

Sorry but that's a really rubbish explenation. I must double post to say that this has no solution, and must be impossible.

 

Pincho.

[Sayonara]

No, that's not the only explanation that makes sense - it's the only one you can understand. That's not enough reason to declare it "impossible". You haven't even said what it is that's "impossible". Time travel? Inter-dimensional travel (god I hate that phrase)? Putting letters in places?

 

Assuming a single timeline dynamic with (and then without) pre-destination effects, it's perfectly feasible to logically consider the possibilities - it doesn't have to be "right".

 

Assuming multiversal travel, pre-destination effects become less of a problem and more of a benefit to any explanation.

[YT2095]

well assuming he DOES put the letter in succesfully and nothing happens to it for 10 years, it just sits there. surely it must still exist in SOME Universe, even if it`s not the one he orginaly came from or goes back to.

assuming that`s the case but theres inter universe "Sliders" type stuff going on, and trying where possible to ignore the most common paradoxs` that occur (we assume).

would his 20 mins make the place he came from have to wait 20 mins?

like 2 cars traveling at the same speed (second for second, minute for minute) but seperated by 10 miles (years) on the same road.

 

And Pinch, don`t worry about it man, that`s why I started it in this section as it`s all a bunch of "Unknowns" anyway

 

[Pinch Paxton]

Yeah it's very confusing, so I backed away from it. I believe that light travels through time, and electrons. Where does this get me? I think it gets me to strings, or Dark Matter, you are left with a wave without the sufficient energy to move a letter. Something like that.

 

Pincho.

[YT2095]

we all travel through time, at different rates according to velocities sure

my jury`s still out whether or not Backwards time travel can be acheived or not.

this thread is all about hypothesis (educated guesswork) etc...

there`s no Exam, just a general chat

[Sayonara]

If you are travelling through time at a greater rate than me; then am I moving further into your past?

[Pinch Paxton]

Ok, so the box would have to have been around for 10 years. So they put it there 10 years ago. If they open it 9 years ago the letter should already be there, so why bother going back in time at all? It's a paradox. So now we don't go back in time, and suddenly the letter is not there again.....??? Lol! I can't cope with the topic, I'm giving up with it.

 

Pincho.

[YT2095]

yes, albeit impercepibly, didn`t they do that experiment with the 2 Ceasuim beam atomic clocks flying opposite directions around the world and the time on the clocks showed a difference from the departure setting.

so yeah it would, but when at a rest frame all`s synched back together again leaving only the effects (as far as I understand it anyway).

[alvloh]

sorry guyz this is my stupid opinion .... i mean if he is destined to put the letter in the box .... then the letter will b there ...therefore i think the time when he start the ime travel the people in the future will automatically have the info of a letter in the brain and they wont realise that the letter just pops out in mind suddenly ... its like a guy who doesnt know abc will know abc suddenly without realising it

[alvloh]

in quatum physics there r scientists who claim that we r actually living in a multiverse therefore when the guy travel back in time he actually reach another world and the world he came from wont have anything in differences...bcoz they claimed something like if the guy change the history by putting a letter in a box in the past then before he goes the letter thing will pop in their mind automatically so the paradox is wether they want to put the letter 1st or the letter thing which pop in their mind make them do that

[YT2095]

Wow, very interesting!

 

it almost raises the question that if/when time travel becomes a reality, will there be such a thing as "Free Will"?

[Sayonara]

We have that question without knowing time travel exists.

 

Although it will be more interesting with a time travel element, and possibly also testable.

[Cap'n Refsmmat]

My theory is it would have appeared in 2080. Because that's when it was put there. And, if, in 2080, they get it, they can't decide not to send him back, because then it never would have arrived.

Weird.

[aman]

Trying to see it intuitivly has smoked my brain a little but my opinion comes from the resulting charcoal bits in my head. I imagine that the future might exist in a different phase so if you went back in the past you would exist like a ghost and put a ghost letter into the box that nobody could see. Then back in the future/present that you came from, the ghost letter would come back into phase in the box at the moment you left for the past. This way the instant you take the letter into the past it appears in the box. The rest of the time earlier it is a phantom letter in the box.

With entropy the energy levels of space-time should be getting weaker so the levels of our existance are different and only compatible with other matter existing in our present. Maybe.

Just aman

[swansont]

yes' date=' albeit impercepibly, didn`t they do that experiment with the 2 Ceasuim beam atomic clocks flying opposite directions around the world and the time on the clocks showed a difference from the departure setting.

so yeah it would, but when at a rest frame all`s synched back together again leaving only the effects (as far as I understand it anyway).[/quote']

 

Yes, the Hafele-Keating experiment. It just confirmed what the theory of relativity was predicting. No time travel, in the sci-fi sense.

[Sayonara]

How does it show that exactly?

[swansont]

The H-K experiment? Planes with a cesium clocks travelled westward and eastward for a number of hours, and a clock stayed on the ground. From the point of view of an inertial observer (not on the earth), the plane that moved west was travelling the slowest, and its clock sped up relative to the ground-based clock. The eastbound clock was going fastest, and it slowed down relative to the ground-based clock.

 

There was also a change in the gravitational redshift, because the planes flew at some altitude, and clock rates depend on your gravitational potential too. The overall effect was consistent with the predictions made by relativity.

[Sayonara]

I know what the experiment was; I'm asking how the results show that "sci fi" time travel is not possible.

 

(Bearing in mind that relativity does not apply to all forms of sci fi time travel).

[YT2095]

here`s an idea, can one of Newtons laws be totaly discounted by rellativity, as in: "Every action has an equal and opposite reaction"

so if a body were to travel at near light speed and go into the future by lets say 1 hour, could it be said that he stayed the same and the universe went BACK 1 hour?

bear with me here!

 

what I was thinking is that greater effect of time change happened to the guy in the spaceship doing nearly C, but a lesser effect happened to US as well, pushing us back a little (by the mass percentage differential), and so to create a 50/50 effect where half went back as well as half went forwards by half hour each, you would need to shift exactly 50% mass of the entire universe to accomplish this. could that be why it`s said to take Infinate energy to accelerate a particle to the speed of light?

[swansont]

I know what the experiment was; I'm asking how the results show that "sci fi" time travel is not possible.

 

(Bearing in mind that relativity does not apply to all forms of sci fi time travel).

I didn't mean to imply that the experiment precluded sci-fi time travel. I was just clarifying that clocks ticking at different rates in the experiment was not an example of sci-fi time travel. Nothing in the experiment travelled backward in time.

 

Put another way, sci-fi time travel always boils down to how do you get around the causality problem. There was nothing acausal in the H-K experiment.

[Sayonara]

Oh, I see what you mean now.

 

I was reading it as "[There is] no time travel, in the sci fi sense".