I'd like to know people think about time travel and time machines,

Such machines have not yet been made and no one has ever done a time travel before ,many claim it to be impossible.

Tell us what you think about it....possible or not ?

I saw a special on the 10 Dimensions that shape our existence (what we live in being the 3rd). A forget which specifically, but one of the Dimensions, by it's very definition, enabled feasible time travel. Should find that and link it.

I think the real question is not the plausibility of time travel, but the practicality. Assuming it was possible to implement time travel on a commercial basis, there would be obvious limits. Future traveling would be nigh impossible. In keeping with the details of an entropy universe and existence as ours, there would be far too many variables and possibilities to allow successful, or even safe, visiting to future destination. That said, it's doubtful that traveling back in time could be reversed, since once you arrive, that time is the present, and you cannot jump back into the future of that time.

So traveling into our futures is out. What's next?

Traveling to previous eras could prove to be either dangerous or harmless, depending on the circumstances. Supposing you went back and altered the time line. Countless lives, existences, events, places, and so on and so forth would be wiped out in the blink of an eye, not dead, not forgotten, having never existed, and something new would spring up in it's place. A popular use of time travel is preventing WWII by assassinating Hitler. Let's assume that a future Time agency hires a hit man to travel back to Pre-WWII Germany and put a bullet in Adolf's head. What next? Well, any families, friends, or relationships had over the war would be nonexistent, and future generations would be, as Ray Bradbury once put it, "Throttled in the womb." Soviet Russia might make use of the lack of a strong western defense to further it's boundaries. The American depression is not interrupted by the war...the list goes on and on. And even assuming you could get away with it, as the time line shook out its sleeves, it popped our assassin out of existence *Snap* just like that, or *Snap* erased his memory of a history that never happened. If this is the case, then our Time agency never sends him back in time to kill Hitler, either because he doesn't exist or no one has any knowledge of WWII, so Hitler rises to power regardless, leading to the conscription of the aforementioned hit man...it's a vicious cycle. Some argue that such measures might possibly rip the fabric of reality and cast all of the cosmos into destruction.

The other, somewhat more pleasant argument, is that any changes or alterations to the time line have already been made. That is, assuming time is fully linear and not branching in multiple paths, that if you travel back in time and cause something, you will cause something that by your time had already happened, because you caused it. Again with examples: Let's say you read about some policeman who found a historical figure dead, and an unknown presumed assailant found right next to his body was caught and put to death, but there are no records of who this person was. So you travel back to the night when this person of history was supposedly killed, sneak into the room where his body was found. You find him dead in his chair. Hearing a noise, you grab a nearby object just as the police walk in and find you with an empty revolver. You are tried, convicted, and put to death, years before you'd ever read about it. A morbid example, perhaps, but it serves a purpose.

In other words, there are really only two uses for time travel. First would be first-hand studies of historical events. Another popular use I've heard for this one is people back checking various religious figures (Jesus, Bhudda, Muhammad, etc.) to see if they were truely divine or if they existed at all. Things such as that. The other application would be teleportation, say, using a time-skip to travel instantly over the course of a Instant (the fastest measurement of time) from site A to site B. It would certainly revolutionize travel, but would have obvious problems with exact localization. People could use this technology to break into houses or tour the seven wonders of the world.

My two cents...in change.

Its just not possible to do time travel !
All this explanation comes into play when we can do this.
Traveling to future and past is only a thought , nothing more.
We cant time travel just like that !
Its impossible.
Theories in physics dont support that !

The explanation about the altering of present due to changes in past and future is right, but i dont think time travel at the first place is possible.

My argument was only based of the premise "What if." The theory of time travel has several logical fallacies and impossibilities to function properly, but if we managed to work it out, what then?

Actually i dont think they really can be worked out.
With the current theories we cant.

Einsteins Mass-Energy relation says E = MC2.
Now if a particle has the energy equal to that of light than it would have infinite mass as the energy would be infinite. By infinite I mean , it could be very very very large or very very small.... this is impossible as no object can have infinite mass !

Basically we cant surpass the speed of light.
In order to time travel we must do that.
Once we start travelling with that speed the time would become stationary for us and once we surpass that stage than we sould be able to kind of dilate time time travel.
But due to the above reasons we cant.

Again, I understand that Time Travel is near impossible, as you've nailed down twice now. I was merely reflecting on how limited our use for such an ability would be anyway. Impossible? Most likely, but you did ask what we thought.

The fact about altering the present .... where did you read about it ?
I just read a couple of pages from some book and forgot about it.

Read about it? I strung together bits and pieces from Time Travel mythology and drew my own conclusions. Hardly original thinking, though; I've found similar theories on Wikipedia.

I remember reading about it ...... many people in my class also had a discussion on the same.

Actually i also remeber seeing something related to this on the discovery channel.
so i just happen to ask.

Of course time travel is possible!

We're constantly doing it! Sure, only in one direction, but...

As for travel the other direction, I really don't know. Not possible with current tech, I'd imagine, and opens up tons of potential paradoxes. Makes good fiction, though.

*Renders the paragraphs I wrote devoid and meaningles.*

Time machines are not yet proven and invented though we can see some in movies like Timeline...It's awesome if it was true...Time wouldn't be a problem anymore...

I dont agree to that.
We are not doing time travel now.... we are just moving with it.
To travel would means to get displaced and not only move with .

Time travelling is very impossible,we can't go advance or go backward ,what happened is past and we can't change it...

And why may i know you think so ?

Its the same for all inventions too.
Before the bulb was invented people never thought they would have something like that.
and it was considered Impossible to fly before the right brothers did it.

Amol, I have to wonder just where you're going with all this. You start by asking our opinions, then summarily explain how Time Travel is impossible, then go on to say everything is thought to be impossible before it is achieved.

Just what are you batting at, eh chap?

Ummm... I'm confused my self about this topic.
I want to know as much as i can but at the same time the other person give me substantial !

Well we are basically travelling through time right now. People have gone "forward" in time by 10ths of a second (Astronauts) and when you hop on a jet and cross five time zones in one hour you have technically gone forward four hours (I think) but I think it's impossible to travel backwards through time.

No it wasn't.
1) People had seen birds fly, therefore they knew it was possible. now landing on the moon...
2) The Wright brothers were not the first to fly, the Chinese used to have giant kites that could support people. Sone Ausie (If I recall correctly) made the first powered flight but it never became famous (plus it was bearly off the ground and only went a short distance).

I'm having a hard time figuring out why we would need to be able to travel at the speed of light to time travel.....That seems irrelevant....

@cmChimera lets take an example and explain this thing.

assume the time to be a river flowing in one direction.
We are flowing with it now that means traveling with the speed of time.
Now the fastest thing is light , thats all electromagnetic in nature and only has energy.
When we travel with that speed time would sort of dilate , meaning that we'er now free of the rivers control in moving, so we could either move backward or forward in the river irrespective of where the river (or time) moves. I hope its clear from this.

If you want i can use pure physics to explain the above too. Not purely pure , but i'd surely try to.

This is a confusing subject. I think that the concept of time is overrated and should just be left alone, but I also don't know that much about time travel.

@Popo: What you describe as traveling faster in time isn't really time travel, though. It is just a relative shift of where you are in position to the sun, but the actual rate of time passing is still the same... I'm sure you knew that, but it was just to clarify that what you said is not actually 'time travel', in the conventional sense.

I do not believe time travel is possible. I just think it is a fantasy. I believe time is linear, and there are just too many things that would become inconsistent if one actually could travel through time, therefore, I do not believe that one could travel through time... without majorly effing it up, at least, and possibly destroying existance as we know it.

My understanding is that there are quanta that do in fact appear to move faster than the speed of light (i.e. quantum physics issues and the fact that quantum physics is not in synch with other physics). - I'm not an expert in this, but I believe that there are in existence experiments that suggest particles moving faster than the speed of light in the quantum world.

Anyway on to time travel:

Per relativity, we can time travel forward in one way of speaking. Take the classic example of a set of twins where one twin is sent into space nearly the speed of light on a mission and the other stays on earth. When the one sent out returns, 20 or more years could have passed, but his body and experiences will appear as far less than 20 years. The twin who stayed behind on earth is now 20 years older. It's not time travel in probably the main sense, but it is possibly a form of one directional time travel.

::edit:: I should have read Popo's post since he already touched on this option.

How do scientists really know this? Have they experimented? Because I have never heard of sending someone to space for twenty years and back. I wouldn't take it for fact, but more of a theory. And really, right now, all we can do is theorize. I mean, it doesn't make sense that just because you are somewhere else or whatever, you would age less. Maybe the environment you are in can make it "appear" you are younger, but will this really extend longevity? It just seems like a very odd theory.

I am no physicist or anything and don't know if real scientists propose that we must travel faster than light for whatever reason to travel through time. It just seems it is always the case in science-fiction. If anyone can explain, please feel free to.

That would still leave to question what would happen to the space time continuum if conventional time travel were possible.

Talking about quantum physics means taking infinitely many assumptions into account.
There is a possibility of anything happening , but the probability only suggests that only 1 event can happen at a time. According to Quantum physics there can be many possibilities .....

As for the quanta that appear to move faster than light , I thinks its only the photons and photo electric packets that move with the speed of light, but they are the basic constituents of light and infact the only constituents so they move with that speed.

I believe time is how earth rotates around the sun (and revolves) so If we could fly or reach a certain speed (don't remember the actual speed) then one could stay at the exact hour forever! but if he could go faster and in the desired direction he could either surpass time or go back, but going in time doesn't mean the whole world is, it just means you the only one! and it Only last for 24 hrs (a day) because eventually your going to go back to the point you reached THAT speed which will cease the effect.
-my theory.

This is theory, however, based on what's called a "thought experiment". It's basically taking the collective theories into account and thinking about what would happen. These are quite foundational in science and in everyday life (you do them all the time when you wonder what x will do if you do y).

You are right, however, that it doesn't prove anything so to speak, but it does give us a "best guess" that's much better than blind guessing.



Perhaps I will discuss this more below vv

[EDIT] I didn't, sorry[/EDIT]


Again, I'm not a physicist, but I would prefer not to take the option off the table completely. We still have not studied every natural phenomena in the universe and because of that, we do not really know exactly whether faster than light travel is possible.

Secondly, I am not certain that faster than light travel is a necessary condition of time travel.

[EDIT] I had intended to look at this, but I first realized I needed to define what we are talking about better so I can even begin to see whether speed of light plays a role in time travel. It wold take more of my time to write out and develop these thoughts on the subject before I can show one way or the other, but I still want to leave it as possible that moving faster than the speed of light is not necessary to time travel [/EDIT]

Monodirectional Contiguous Time Travel working definition:
A spacial object existing in more than one point of time where each temporal point being successively later and contiguously following the previous temporal point.

- For example, Object x exists at t1 and exists at t2 where t1 is 1pm and t2 is 2pm (i.e. the time has moved forward).

- THis needs a statment about the relative speed of the object to the speed of light, but I'm too lazy to add that.

- The space man thought experiment follows this as well, however, there are two temporal rates being measured.

- Needs qualifier to state that object cannot exist twice in the same time point (only one object x can only be in t1)

Multidirectional Non-Contiguous Time Travel working definition:
A spacial object existing in more than one point in time where each temporal point in question is not contiguously followed by the previous temporal point.

- can be successively later (i.e. exists at 1pm and then at 2pm, but not between 1:01 and 1:59)

- Needs a qualifier for the same object existing twice at the same time (i.e. object x exists at 1pm and object x time traveled to 1pm at 2pm creating two object x's (x1 and x2)

....

Alright, I'm already sick of this. It's clunky and needs expansion, but it's clear that until it gets defined, time travel debate can't even begin. Also what other options exist? I haven't looked at time seriously metaphysically in nearly 10 years, so I'm very rusty about my time metaphysics

Nicely explained, Nepharski.
I think time travel would just end up badly. People shouldn't mess around with time.
Then again, time is nothing more than an illusion with a purpose. How could someone make a machine that can "travel" through something that you cannot see, hear, feel, etc.? It's impossible.

Machine is only an idea... it could done with a machine too.
I think its possible.

Try using the mass-energy relation and equate it with speed of light, that way its possible.
But its only theory.

If this was made available to us, say time travel, what would you do? You could alter things so bad here that would mean an horrific future(as if we already don't live in a horrific time). I'm just saying, what would be the point of altering things which may have unexplained consequences. Even if you want to do something noble like stop World War II or something, it would have an astounding affect on today's world. Just my thoughts.

History should never be altered. What has happened has happened for a reason, even if it does seem horrific. If you killed Hitler and stopped WWII, for example, we would all be more suceptable to things like that in the future... present? Anyway, it's not up to people to police the past. All we can do is study it and learn from our mistakes. People are foolish creatures and need to learn from experience, not just by hypotheticals.

I agree. Sometimes things just shouldn't be meddled with. Otherwise, certain things can happen. Even so, I don't think time travel is going to happen anyway.

Personally, I hold with the theory that whatever has been "Altered" through time travel has already been integrated into the timeline. See my earlier arguement for details.

@Nepharski
Your other post concerning the altering of the timeline is very good, I must admit. I do agree that somethings could be intertwined with the timeline, but that is far out to me. I bring up a very important thing when I say, "To every action (force applied) there is an equal and opposite reaction (equal force in the opposite direction).
Another way of stating Newton's third law is that if object A exerts a force on object B, then object B exerts a force of the same magnitude on A, in the opposite direction."

I know that this is the third law of motion, but it could be applied to the timetable so to speak. Yes, if you changed something vital in time and went back to the present, I think that it would change would you would think. Like you have a history book about WWII and you travel in time. You change history so that WWII wouldn't have happened:lol: and then proceed to go to the present. When you are in the present, do you think the history book would have "changed" right in your hands? Just my two cents.

I dont agree to that.
Third law of motion doesnt have any effect ...... its only alteration !
And one more thing.... how can equal and opposite reaction happen in another dimension ,
The law is only confined to a limited system !

@Amol:

The third law is like saying if you did this, you would have a reaction, which would start another reaction, and so on and so on. It is not alteration. It is cause and effect. So saying that you cause another World War during your time travel, wouldn't it have a little effect on the timetable.

@Vash_the_Gunslinger

Newtons Third law of Motion is only applicable to a system of particles !

Example : assume an external force acting on a body.... according to this law , the particle would also exert a force equal in magnitude but opposite in direction !

This is but only applicable to system as i have mentioned before, as time travel takes place according to the 4th axis of time and dimension, it would not have any effect until the two worlds a part of the same system !

I'm not much sure of it , but i think its only a partial change or alteration that takes place.

this is really confusing
but I agree with nepharski aboout the altering timeline thing.