Time travel is not possible - would you agree?

[wazzuuup]

Hey everyone,
One standard definition of time travel is that of David Lewis's: an object time travels if the difference between its departure and arrival times in the surrounding world does not equal the duration of the journey undergone by the object.
I therefore believe that you can't travel in time without travelling in space. Wouldn't we therefore have to call it spacetime travel?

Please argue anything, I'm a fourteen year old girl working on a project. If I am wrong, I would please like to know!

[Uncle Martin]

From what I understand time travel is not ruled out by any physical laws. The energy requirements and mechanics of actually achieving it seems rather unlikely to me. Of course we are all tavelling through time as a default function, the real trick is to either accelerate or go in reverse. I wish you luck with your project,... could you tell us more about it specifically, that may help to steer the discussion in a more helpful direction.

[wazzuuup]

If one were travelling with one 'Earth second' per 'Earth second' in time on the planet Earth while going from point A to B, it is not 'time travel', because the difference between your time of departure and arrival times in the surrounding world equals the duration of the journey ondergone by the object.

[wazzuuup]

But, if you were to move at 99.9 % the speed of light for five years towarsd Alpha Centauri, and then come back again (taking another five years), 70 years would have elapsed on Earth. This would be calculated suing the equation

dt= 1 / ?(1-(v^2/c^2)) * dT

dt would be the coordinate time (earth time) and the dT would be proper time (travelling 10 years)

However, my argument is that you can't achieve any time dilation or other form of travelling in time where your time is different to the surrounding world's without travelling in space.

THus, we should call time travel space-time travel.

[wazzuuup]

* the ? stands for a square root in the above equation

[Freethinker]

Originally posted by: wazzuuup
* the ? stands for a square root in the above equation

Do you IRC?

[Freethinker]

Originally posted by: wazzuuup
THus, we should call time travel space-time travel.

I can't say I find anything specifically wrong with your construction nor assertion.

What I am wondering is, is this a etymological question more than a physics question?

Yes it would seem that it would be incorrect to refer to a timespace dilation effect as "time travel". In fact it would seem that it is not even correct to call it "space-time travel". Any time one person/ object is in motion compared to another they will have different "time dilation" components.

Further is the issue actually ONLY termonology given to "time variation" phenom thru relative motion? Or is it whether there is a more correctly termed "time travel" event which would create a timespace anomaly for an individual relative to the norm?

[wazzuuup]

Originally posted by: Freethinker

Do you IRC?

What would IRC mean? I'm sorry, but not everyone's first language is English.
When I copied and pasted that equation, it was a square root, but when I pasted it in the forum, it suddenly turned into a question mark.. the rest is self-explanatory.


But anyways, back to the topic. I didn't want to go into any etymology or termonology of the word 'time travel'. My apologies. I was just wondering if you could reverse or accelerate in time without moving. Theories about wormholes, superstrings, time warps, Godel's Universe etc. all include space.This is why I thought of naming it 'space-time travel'.

I agree that when one person/ object is in motion compared to another, they will have different "time dilation" components. But would this imply that every single moving object would time travel, despite the miniscule slow-down factor? And isn't everything moving?

[Freethinker]

Originally posted by: wazzuuup
What would IRC mean? I'm sorry, but not everyone's first language is English.

Actually IRC is not english specific, anymore than other termonology used on the net. IRC is Internet Relay Chat. You might say the original chat room, IM group or Blog. And still better.

* the ? stands for a square root in the above equation

If you make a mistake on a line of text you just sent, you correct it by starting the next line with an "*" followed by the correction, just as you did. So I thought I would ask.

More at

www.irc.org

But anyways, back to the topic. I didn't want to go into any etymology or termonology of the word 'time travel'. My apologies. I was just wondering if you could reverse or accelerate in time without moving.

OK, well there is a difference between asking IF and stating why. It seemed your first post was more stating why we couldn't and thus why we should change the name. That is why I wnet down the path I did.

I agree that when one person/ object is in motion compared to another, they will have different "time dilation" components. But would this imply that every single moving object would time travel,

When Time Travel is defined that way, then yes that would be correct. Everything moving in relatively different directions/ velocities/ .... each has it's unique GR timespace.

And isn't everything moving?

Or not?

[wazzuuup]

To Freethinker, thank you for all your replies, you've helped me improve my communication and thoughts. But the more I read on these forums, the more confuzed I get.

For example: on 07-08-2004, in the forum 'What will be the changes if we move from 3D to 4D', GAHD said, "Every experiment that has shown any dissonance in clock 'tics' can be disproven, or has had massive amounts of data doctored or just plain ignored (like the Hafele-Keating Experiment). NO ONE has been able to show time dilation occurs except with math (which then breaks down in real-world applications)."

This seems to contradict everything.
I do believe that time dilation has been applied to application. Muons are particles that are produced when cosmic-ray protons strike air molecules in the upper atmosphere of our planet. Normally (at rest), they persist for about two millionths of a second before decaying into energy and other, less massive plarticles; hence none of the muons should reach the ground. However, apparatus places at sea level and atop Mount Washington, New Hampshire, was ale to detect the fast-moving muons and to measure a significantly longer tifetime for them; relative to our fixed (Earth based) reference frame, their 'natural clocks' had apparently slowed down. In fact, while traveling at 99.4 percent of the velocity of light, muons endure for about sixteen microseconds, an eightfold increase in their usual lifetime. This time extension matches to within 1 percent that predicted by Einstein's theory of special relativity. (I got his information from a book "Relatively Speaking" by Eric Chaisson).