Time Travel is Impossible and if not Impractical

[geordief]

Does that lack of an "anchor" (the lack of any simultaneity) in our view of the world lead to a feeling (a psychological feeling only perhaps) that time itself does not exist ?

 

The Minkowski diagrams seem to have time and space measurements using the same units but time and space are different aren't they? Are they 2 sides of a more fundamental coin?

 

Apologies ,mod . I went off topic I see.

Edited December 19, 2015 by geordief

[swansont]

The moderator tells me that saying time doesn't exist isn't fair in this thread, that I should stick to the physics of it.

 

I find it impossible, actually absurd, to attempt a physics of something that has no physical manifestation.

 

I encourage everyone who would contemplate "doing" physics on, about, of for any topic to first determine whether or not that topic has any physical manifestation. Time certainly does not. Time "travel" is fiction, not physics.

 

!

Moderator Note

If you find it impossible to discuss, then perhaps not posting in the discussion would be the proper choice. The possibility or impossibility of time travel is physics, so please stay on topic (which would include not responding to this modnote in the thread)

 

!

Moderator Note

Addendum: further posts that are not on the topic of time travel have been split off to the trash

 

"please stay on topic" has no hidden meaning

[Tronic]

I'd like to jump in and say time-travel however possible would be the easy part in achieving the desired effect ie going to watch an old concert. The harder parts would be ending up at the right location, problem lies with all reference points moving at different speeds in different directions forever changing like the weather. A mis-calculation of smallest degree would throw the traveller out in outer space. A different kind of anchor point could help.. stuck to earth like a magnet, always present throughout the entire time period as a marker for landing. The sub-space warp would need it's own time-machine inside the worm-hole to act like a regulator, otherwise what's to stop you taking a million years to get through when your desired trip was 5 minutes, even if the worm holes were side by side for testing? Could get lucky. Might be a practical speed woven into them already such as instantaneous but then you'd have problem of tearing while being half in half out. A snapshot/teleportation device would be needed at each end, like an airlock.

[Sensei]

I'd like to jump in and say time-travel however possible would be the easy part in achieving the desired effect ie going to watch an old concert.

 

While breathing you exchange CO2 and O2 with environment you are in.

These molecules become part of you,

and your molecules become part of air around you and fly away.

Not to mention exchange of viruses and bacteria.

Matter that is in all these molecules are somewhere in the same world/universe already in completely different place, in different time.

 

Proton that yesterday was in the Sun, billions of them are accelerated to relativistic speeds, with lucky they end up as primary cosmic rays hitting atmosphere, today they can become part of atmosphere, tomorrow they can join with Oxygen, and form water molecule, and you can drink it.

If you time-travel 3 days from now to the past, there would be two copies of each atom, each electron.. Proton (Hydrogen) in some water molecule in your body, could be couple days part of the Sun.

[Tronic]

Supernovae might show up in worm holes like a ticking clock?

[goubios]

what if actually you cannot travel back or forward in time but the fastest you can go is instant. this would make sense with the classic example of wormhole with a sheet of paper.you draw 2 dots (the present position and the destination position),you fold the paper (the sheet indicates all the physical dimensions width length etc.) and what you have is an instant transition from point A to point B. This solves the time paradox validating the progresive nature of time.

[The Think3r]

You can't travel thought time as in forwards or backwards, but it is theoretically possible to travel sideways though time to an alternate time line right along side our. Its not really time travel but it's as close as we can get, because even if you come back over and indeterminable amount of time will have passed, and that's if you even get back to the right dimension.

[Phi for All]

Its not really time travel but it's as close as we can get, because even if you come back over and indeterminable amount of time will have passed, and that's if you even get back to the right dimension.

 

"The right dimension"? A dimension isn't a place you can "get back to".

[Delta1212]

You can't travel thought time as in forwards or backwards, but it is theoretically possible to travel sideways though time to an alternate time line right along side our. Its not really time travel but it's as close as we can get, because even if you come back over and indeterminable amount of time will have passed, and that's if you even get back to the right dimension.

That's probably one of the least likely ways for time travel to "actually" work, even if that's the most convenient way to make a logically consistent time travel story work.

[The Think3r]

 

"The right dimension"? A dimension isn't a place you can "get back to".

 

There are hundreds of(if not thousands) planes of existence, so you can't really get back to you plane or what you perceive as your place of origin. Say you travel "backwards" in time and change something you would not be able to travel back to your "present" because it would not exist. But with dimensional travel/time travel you can get back to a reality exactly like or as close as possible to your original time/dimension.

Edited April 8, 2016 by The Think3r

[Delta1212]

There's no evidence that any of that is remotely true.

[The Think3r]

Not at the moment. Maybe in a couple hundred years if not a thousand or so. But remember this is all in theory. If there were evidence of this then we would have been,at the very least, notified that scientist were researching this. And beside this is what i believe could or could not be possible. Believe what you will but this is what I conceive as possible in regards to time travel.

[Strange]

That is still not what "dimension" means ...

[Delta1212]

That's also not what a theory means. A theory is something that had been worked on extensively and has explicitly outlined methods for how to test it, some of which would ideally have already been implemented and provided some evidence that the theory is correctly modeling what happens in reality. But it will still be a theory when that happens.

 

The word you are lookin for is not theory, in a scientific context. It is "idea."

[Phi for All]

And beside this is what i believe could or could not be possible. Believe what you will but this is what I conceive as possible in regards to time travel.

 

Well it's wrong, and you should correct that.

 

You're basing your "beliefs" on rotten information, and the emotional conviction that you're right. That's not science. Please look at some of the recent replies. There is ABSOLUTELY NO EVIDENCE that there are "other planes of existence", much less hundreds or thousands of them. And whatever you think those "planes" are, they certainly aren't dimensions. I gave you a link to educate yourself about them, and I suggest you use it.

 

You can't just make stuff up without evidence to support yourself. That's not science. This is why we discuss science here, to trim away what is false or wrong from our ideas, and examine the supportive evidence for what's left, and form the best explanation for a specific phenomena.

[Delta1212]

It's important not to confuse thought exercises that examine different ways that time travel could function, hypothetically and usually from the perspective of dealing with paradoxes rather than nitty gritty mechanics, with a scientific discussion about how it would work (if at all) in reality.

 

Just because you've found a way that makes the most sense to you (and as an avid science fiction reader who likes time travel stories, I have my own ideas about the "best ways" for it to work) doesn't obligate reality to conform to that idea. We have no idea whether any kind of time travel is even physically possible, and in the event it is, there is no reason to think that it would look like your preferred method just because you think that's the one that makes the most intuitive sense to you.

 

Even if we take it as a given that time travel is somehow possible (which is a huge leap just to start with), speculating that it will look like what you've outlined is like someone from ancient Greece speculating that humans will eventually be able to build things that allow them to fly, and that those things will be wax wings with feathers on them because that's what Daedalus and Icarus used in that story they like, and that just seems like the most natural and elegant solution.

[jev1969]

My first post so go easy if I missed one of the rules but this is one topic that I've always found fascinating (though not my particular forte) so I had to jump in.

The original poster titled the thread "Time travel is impossible if not impractical". As with most challenges in science I find that I enjoy playing the part of devils advocate so I will take the position that time travel may indeed be possible, strictly as a thought exercise. I will begin this fools errand by taking a different approach and tossing into the arena Gravitational Time Dilation. Without getting into the complex formulas and keeping this strictly as a rudimentary thought exercise, would it not be considered "time travel" if one were to leave the earth in 2016 and return in 2416 having only been gone a few hours? This could be achieved by leaving the current gravity well we all currently reside in and place oneself near a gravity well of much larger mass for a period of time. Upon return, the "traveler" may have only experienced hours where those near the smaller gravity well will have experienced decades or centuries. Could it then be said that the traveler traveled to the future?

Now although negative-mass is strictly hypothetical if it were to be proven then that would lead one to conclude that there would have to be objects in the universe comprised of it and therefore the existence of negative gravity wells giving the traveler the ability to return to his/her point of origin in space/time.