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Time Travel - An Impossibility? Is time travel possible? Will we ever manage it? What are the dangers?


HDuffRules

There's some theory somewhere that I'm not too familiar with, but it involves falling into a black hole and there being some possibility of you traveling backwards in time. Although with what we know about black holes, people are unlikely to want to test this theory... I think going backwards in time is theoretically possible, since time is basically just another dimension, and if its possible to travel in the three physical dimensions we're familiar with, it should be equally possible to travel through time. Unfortunately, the dynamics of going back in time and the consequences of what might happen would basically cause it to be outlawed as soon as the technology for it exists. Governments certainly wouldn't want people to have the ability to randomly go around into the past, simply because we're not sure if its possible to alter the past. Two views exist on that: 1. If you're going to go back in time and change something, then in the past you've already done it, so when you return to the future, nothing will have changed. 2. If you go back in time, you are physically doing something and changing stuff, so the future will be different. I prefer not to think about this theoretically, but more thinking about particles. Everyone is made up of atoms, etc. whatever. So when you go back in time, the atoms that make up your body appear in a different time. But those atoms already existed at that time ie. in the past. Some law of physics says the same particle can't occupy two different positions at once, so you didn't really visit the past, you basically created an alternate universe that's exactly the same except for the molecules are comprise you. This would explain why "time travel" would cost enormous amounts of energy, since you're basically causing a ton of quantum calculations to happnen in order to create this new universe you travel "back" to. Now as to whether or not you'd actually be able to return to the "present".. that's something I actually can't decide...


csp4.0

It is just purely impossible to travel backwards in time... Imagine a rocket ship with rockets positioned at the back... There is no way for it to "reverse" same thign with time... Meaning the reversing time would be impossible...We can't actually go forward in time... But by manipulating time (Well, not actually US manipulationg time, the black hole would be and we'd be just using the black hole for good use...), we can possibly seal some things/people in like a "Time Capsule" which time will go normally for them, but the world around them (Outside of the dilation field), Time would seem to go extremely fast...Black Holes distort time... And if white holes do exist, here's a theory... If time goes slower the closer you get to a black hole, then once you get inside (i.e. past the event horizon), then time should go backwards, meaning if white holes do exist, they are probably from the future... Let me put this into an example... Imagine a cassette tape... We are currently moving along at "Fast Forward" speed... We enter the time dilation created by the black hole, and we go into "Play", as yo uenter the event horizon, it goes to "Pause"... The cassette (i.e. Time, stops altogether...)... ... Now we start going backwards as you're inside the black hole, travelling through the wormhole... We go to "Rewind"... Time goes along like normal for you, but it is changing on the outside world... Time rewinds faster and faster until you exit the white hole (You won't be alive, so... eh... Theory can't be proved... ) To you, it would've been normal time, but... Time would've reversed...The only flaw to that, it (the whitehole), should eject you at the same period of time you entered the dilation field... Since time is sped up, and then reversed... So.. Yeah...


joeblogg

i think it is definetely impossible to be able to travel to the past and change things. i mean it doesn't make sense.

 

so if you go back in time and kill your grandmother she won't be able to have your mom and you mom won't be able to have you so you won't exist right? if you don't exist how can you go back and kill your grandmother?

 

that is just one of the reasons why you can't just travel back in time.


Unknown_99

There's some theory somewhere that I'm not too familiar with, but it involves falling into a black hole and there being some possibility of you traveling backwards in time. Although with what we know about black holes, people are unlikely to want to test this theory...
I think going backwards in time is theoretically possible, since time is basically just another dimension, and if its possible to travel in the three physical dimensions we're familiar with, it should be equally possible to travel through time.

Unfortunately, the dynamics of going back in time and the consequences of what might happen would basically cause it to be outlawed as soon as the technology for it exists. Governments certainly wouldn't want people to have the ability to randomly go around into the past, simply because we're not sure if its possible to alter the past.
Two views exist on that:
1. If you're going to go back in time and change something, then in the past you've already done it, so when you return to the future, nothing will have changed.
2. If you go back in time, you are physically doing something and changing stuff, so the future will be different.

I prefer not to think about this theoretically, but more thinking about particles. Everyone is made up of atoms, etc. whatever. So when you go back in time, the atoms that make up your body appear in a different time. But those atoms already existed at that time ie. in the past. Some law of physics says the same particle can't occupy two different positions at once, so you didn't really visit the past, you basically created an alternate universe that's exactly the same except for the molecules are comprise you. This would explain why "time travel" would cost enormous amounts of energy, since you're basically causing a ton of quantum calculations to happnen in order to create this new universe you travel "back" to. Now as to whether or not you'd actually be able to return to the "present".. that's something I actually can't decide...


Exactly what I had been thinking. So all I am going to do know is to agree with him right? If you went back in time to do something you feel like you should be doing, then that would already be a part of the past. Everything you are to be doing in the past, no matter when you came from, as long as it is executed in a previous time, is part of the past. It will be considered a future action done in the past, or a past action done in an even earlier past. Its just like digging a hole inside a hole.

Echo_of_thunder

who knows if someday we will be able to go ahead or back in time. But as for today there is no way to tell. we would have to not only go faster than the speed of light but to barrow a phase from star trak Faster than warp speed Mr Scott. Besides why would we want too. to change history? that could be dangerous. things have been set in stone to happen and they will happen. You think you can "change" it but are you? No your not. because it was already ment to be.Thank about it


cemeteryrecords

I originally belived time travel could be possible, but think about this: If, in the future, we figure it out. Wouldn't we have some type of evidence of someone in the future coming back to now? I mean, think about it! Lets say, in...2100, they figure out how to send a person back in time. Wouldn't they come back to now and be like, "Ha! We got it!" Maybe even tell us how? Or If something bad happens, or somebody does something dumb (*cough* nukes *cough*) They could wrn us! I mean, if you look at time as a linear, people 500,000 years from now STILL havent figured it out, because I'm sure they would've cam back to now. (unless our time just sucks) OR! Earth didn't even make it that far in time, cause the rate we're going, we're gonna blow this baby up! Or kill each other, whatever comes first. This is why I don't quite believe in time travel.


DeM0nFiRe

Well, here's the problem with time: How is it measured? Like, if you want to make a rope shorter, you take out some rope. What is rope? Well it is matter, you just decrease it's mass and you've got less matter. How do you do that with time? Well, theoretically, time in a system can be measured by the amount of entropy (The tendency of a system to try to change it's state from current to an equilibrium) in a system. For instance, if you were watching a video of a ball bouncing and there was no light changes or other movement in the scene, how would you know which direction time is flowing in the video-- how would you know it is not being played backwards? Well, as the ball runs out of entropy, it is going to bounce less and less each time until it can eventually reach equilibrium (Which would be the ball not being pushed back by the ground with a force greater than the normal force due to gravity). That being said, the only way to reverse time would be to add entropy to a system. The problem with that is that, unlike every other quantity in the universe, once you run out of entropy it is gone. Entropy is not conserved in a system like mass or energy.EDIT: Sorry, I explained that backwards. As the ball continues, more entropy is added to the ball but at some point no more entropy is added because the ball will reach equilibrium. We would have to take out entropy from the universe in order to turn time back.Entropy is added to a system as it tried to reach equilibrium, but once it reaches equilibrium, no more entropy is added.


rpgsearcherz

Well, here's the problem with time: How is it measured? Like, if you want to make a rope shorter, you take out some rope. What is rope? Well it is matter, you just decrease it's mass and you've got less matter. How do you do that with time? Well, theoretically, time in a system can be measured by the amount of entropy (The tendency of a system to try to change it's state from current to an equilibrium) in a system. For instance, if you were watching a video of a ball bouncing and there was no light changes or other movement in the scene, how would you know which direction time is flowing in the video-- how would you know it is not being played backwards? Well, as the ball runs out of entropy, it is going to bounce less and less each time until it can eventually reach equilibrium (Which would be the ball not being pushed back by the ground with a force greater than the normal force due to gravity). That being said, the only way to reverse time would be to add entropy to a system. The problem with that is that, unlike every other quantity in the universe, once you run out of entropy it is gone. Entropy is not conserved in a system like mass or energy.
EDIT: Sorry, I explained that backwards. As the ball continues, more entropy is added to the ball but at some point no more entropy is added because the ball will reach equilibrium. We would have to take out entropy from the universe in order to turn time back.Entropy is added to a system as it tried to reach equilibrium, but once it reaches equilibrium, no more entropy is added.


Something else to consider regarding this though is that everything is as we perceive it in our brains. We could theoretically go back in time. How? Because it is up to our brains what we see, feel, hear, touch, and smell.

If our brain wanted us to think that walking out our front door led off a cliff(how it was 1 million years ago) it could do so, causing you to think that you really fell and have a heart-attack.

So what is time, really? If time is nothing but our perception of a state of matter, our brain is what determines how fast time is, how slow it is, etc.

This wouldn't explain the whole "going back in time" thing, or even "going forward in time," because there are many more factors added in to those, but regardless, I feel that somehow, it's a possibility.

adriantc

I do believe someday we will be able to travel back in time, but not in the hollywoodian sense. Hollywood gives a very romantic view of time travel, a very optimistic view. Press a button, change history, make everything better. If time travel is possible I don't think you can change it in the classic fashion. I think time is like a tree with branches. When you go back in time you create a new branch. That also resolves the "grandfather paradox" as when you go back to your time it's not actually the same timeline.More probable is the time travel in the view-only sense. You can see the past, but not change it! That would still be great as history will have no secrets anymore. And in some way that is easy to do. The only thing we have to do is travel faster then light. If you send a beam of light into space and then travel faster then light and overtake the beam of light you actually see the past. It's not time travel as you only see a reflection of things that happen. In fact we can travel back in time every day when we look to the starts. It takes so much time for the light to get here that what we actually see is what happened millions of years ago. Of course it's not time travel, but the result is still exciting.


DeM0nFiRe

rpgseacherz, that's a nice theory, however it's kind of hard to argue. How can you prove or disprove that theory (Which is called solipsism, the idea that everyone's reality is independant of another's) Either way, I am talking about physically travelling through time. Time, physically speaking, isn't something that is percieved by humans, but is something that is measured. (of course, that assumes that time physically exists. There's still no agreed upon way to define time, as far as I know)adriantic: Your idea is actually pretty farfetched XD You see, the speed of lht is the theoretical speed limit of the universe. Electro magnetic waves all travel at the speed of light, and theoretically the fastest matter can move is approaching, butnever reaching the speed of light. What you are thinking of is called the (I think) Twin Theory, although you butchered it a bit XD. The closer you are moving to the speed of light, the slower time will pass. The Tiwn Theory states that if two twins are born, and one is put in a spaceship going close to the speed of light and the other stays on earth, in 20 earth years, the one on earth will be 20 years older, but the other will not have aged as much. Now, this is just a thoery mind you.


miladinoski

I don't know if you guys know the tale of John Titor — an alleged time traveler who appeared in 2000 and 2001 and claimed to came from the year of 2036. I mentioned him because you asked for a time traveler who (according to some) came to our time (official page) (wiki)

 

Well my opinion on time travel by going in the past is possible, but it's not possible to change anything in the past and for it to reflect to the time you are living in, something like the multi-universe theory (which explains the grandfather paradox). But, I don't think that it'll happen anyways soon (in a relative manner) — it'll happen for 300-400 years or so...

 

And time travel by going to the future is something that is more to believe in, because traveling with speeds faster than the light, or going to live on other bigger planets where you'll stay relatively younger and coming back to the Earth will find many grand-children and really old relatives

 

Me, I'd really like to time travel, especially in the future because I think it'll be more fun and I'll learn more things than going back to the times that were past.


DeM0nFiRe

Well, actually, time travel is obviously a fact. We are traveling through time right now. Time is the 4th dimension, the other 3 being height, width, and depth. And, to a degree we can theoretically control the speed at which we travel through the 4th dimension. As I stated, and miladinoski re-iterated, by moving quickly through the first 3 dimensions you can theoretically slow your progression through the 4th dimension.


miladinoski

Well, actually, time travel is obviously a fact. We are traveling through time right now. Time is the 4th dimension, the other 3 being height, width, and depth. And, to a degree we can theoretically control the speed at which we travel through the 4th dimension. As I stated, and miladinoski re-iterated, by moving quickly through the first 3 dimensions you can theoretically slow your progression through the 4th dimension.

Well you are completely right, just it still can't be prove that time is actually the 4th dimension — which may be easy to prove after a time machine is built. But that's a whole another topic, and as always available on Xisto forums

 

See you there


DeM0nFiRe

Hehehe, yeah exactly it cannot be proven. All of this is, of course, theoretical. It'll be fun to see who is right later on XD


adriantc

rpgseacherz, that's a nice theory, however it's kind of hard to argue. How can you prove or disprove that theory (Which is called solipsism, the idea that everyone's reality is independant of another's) Either way, I am talking about physically travelling through time. Time, physically speaking, isn't something that is percieved by humans, but is something that is measured. (of course, that assumes that time physically exists. There's still no agreed upon way to define time, as far as I know)
adriantic: Your idea is actually pretty farfetched XD You see, the speed of lht is the theoretical speed limit of the universe. Electro magnetic waves all travel at the speed of light, and theoretically the fastest matter can move is approaching, butnever reaching the speed of light. What you are thinking of is called the (I think) Twin Theory, although you butchered it a bit XD. The closer you are moving to the speed of light, the slower time will pass. The Tiwn Theory states that if two twins are born, and one is put in a spaceship going close to the speed of light and the other stays on earth, in 20 earth years, the one on earth will be 20 years older, but the other will not have aged as much. Now, this is just a thoery mind you.


As far as I know faster-then-light travel is already possible. From Wikipedia Speed Of Light article [here]
:

"However, there are many physical situations in which speeds greater than c are encountered." [c=299,792,458 meters per second]. However isn't not matter going faster then light: "Some of these situations involve entities that actually travel faster than c in a particular reference frame but none involves either matter, energy, or information traveling faster than light."

And I do remember an experiment where they accelerated a particle (I think) beyond the speed of light. A particle without mass maybe. I know about this theory and as far as I have heard it's more then a theory. For an astronaut in orbit time passed differently (slowly) then for people on Earth. The difference is very very small - less then thousands of a second - a difference only theoretical not measurable in practice.And there are also the wormholes which allow faster then light travel. It's faster than light to an external observer, but slower than light locally. Everything is relative!
I wouldn't look to the speed of light as a constant forever. Science has a habit of making old theories obsolete. Maybe in 100 years somebody smarter then Einstein will find another theory which will completely change our point of view over the speed of light.

DeM0nFiRe

Right, which is why I said it is the theoretical speed limit. Matter, theoretically, cannot travel faster than the speed of light. Wormholes are quite theoretical as well


rpgsearcherz

A huge question I have now is...Why would we want to travel through time anyways?Obviously we would not be able to ever go into the past. If we could, it would shape the future. Thereby it's a definite impossibility.So the only thing that you could do is go into the future. But for what? To destroy any suprises that you may have? To test out various ways of dealing with situations to see which one is the best?Or is it solely for the knowledge of knowing that you did something that nobody else did?I just, personally, can not think of how I would use time travel to begin with. The only possibility I am capable of justifying would be to show off that I did the "impossible." Aside from that, nothing.


adriantc

A huge question I have now is...Why would we want to travel through time anyways?
Obviously we would not be able to ever go into the past. If we could, it would shape the future. Thereby it's a definite impossibility.

So the only thing that you could do is go into the future. But for what? To destroy any suprises that you may have? To test out various ways of dealing with situations to see which one is the best?

Or is it solely for the knowledge of knowing that you did something that nobody else did?

I just, personally, can not think of how I would use time travel to begin with. The only possibility I am capable of justifying would be to show off that I did the "impossible." Aside from that, nothing.


It's hard to NOT imagine a use for time travel. The main use would be to change history. Pick a point in time, a point where things started to go wrong and fix them. Kill Hitler before the got to power or even before he was born. Or why not make sure there are is Dark Age. The problem is that fixing one problem might generate another, even one bigger then the first. Some may call that unchangeable destiny. See the movie The Butterfly Effect for details!
Another one would be history research. You wouldn't need to actually change the time line, just watch history as it happens. Imagine watching the life of Alexander The Great and finally deciding is he was killed of not or finding our where his body is. Imagine watching Jesus on the cross and finding out if he really is the Son of God. Or imagine seeing Napoleon at Waterloo in flesh and bones. Or finally discovering the truth behind 9/11. Imagine the countless mysteries of history finally unraveled. The possibilities are truly endless!
Imagine what great power we would have, far beyond our current nuclear power. If it would be possible controlling time would surely be an epic point in our evolution. And just like with nuclear power, it may also turn out that time travel can be used as a weapon.

cemeteryrecords

..."Happiness today is the anticipation of tommorow"I agree that we might only be able to go forward in time. Despite the fact that it would very cool to see what lies ahead...wheres the fun in that? Why would I want to go forward in time to see what ruins my day tomorrow? I'd rather just find out what ruins my when it happens! That's the fun and amusement of it!By the way, I love how this turned into, "can it be done?" to "why would it be done?"


DeM0nFiRe

lol, "Why would it be done" would be a completely different discussion XD (Oh, and if any of you jerks change my past I'll kick you in the face )As far as can it be done? I kind of doubt it. At this time, I think it's gonna stay in the sci-fi stories.



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