Thread: Time Travel?

There is something, some kind of particle that is mathematically described to be an electron traveling back through time - I remember reading this in a physics book, but I don't remember what it was.

May have been a positron though I'm not sure at this point anymore.

I don't know what the hell that means, but that is what was written.

Originally Posted by blade5x

There is something, some kind of particle that is mathematically described to be an electron traveling back through time - I remember reading this in a physics book, but I don't remember what it was.

May have been a positron though I'm not sure at this point anymore.

I don't know what the hell that means, but that is what was written.

I believe you are talking about a tachyon. If I remember correctly, current theory suggests the existence of this particle, but none has actually been observed to date.

Originally Posted by Xei

And about freezing bodies; well, technically you're not travelling through time at a rate greater than normall... it's just that you're... well, dead.

Presumably, you're in suspended animation. What's the difference between that and orbiting the galaxy at light speed to suspend your aging? As far as you're concerned, you close your eyes for an instant, and you're in the future... and as far as the rest of the world is concerned, they don't see you for years and years. Same thing either way.

I believe that time travel can be done by thought enstead of using machinery. Travel at light speed to a distant location and back, and you can only go forward and not back in time. Sounds pretty dumb and with poor thinking of how you can be more creative in thinking of a better way to travel in time. But I think the power of the mind can not only take you there in spirit but also in body and both forward and back in time too. Theres many stories of time travel I read. A lot of mystery in this world like a shoeprint found in a layer of dirt that was from before dinosours ruled the earth.

Presumably, you're in suspended animation. What's the difference between that and orbiting the galaxy at light speed to suspend your aging? As far as you're concerned, you close your eyes for an instant, and you're in the future... and as far as the rest of the world is concerned, they don't see you for years and years. Same thing either way.

You've got to be careful though, mental time perception and real time are completley different things.

Mental time perception can be changed, it has been argued, yeah, with things like drugs. Note that nobody's ever recovered from brain stem death though, and it's not known if that's possible; it's also not known how much time the frozen person would have percieved. Logically the molecules of the body are all in the same positions so there should be no difference percieved, but hey, conciousness isn't logical.

The second kind of time is real, physical time, which is what I believe we're talking about. If you could somehow attatch a physical 'clock' to each molecule in the body, it wouldn't matter if they were dead or not. The same amount of physical time passes, regardless of mental states.

I'm pretty sure it's the manipulation of physical time that was the focus of the question.

Of course, there is the whole subjective argument that there is no time except that which is percieved by the mind, but er... let's not even go there.

Even if you manipulate time and "go" (whatever that means) to the future, to the people NOT travelling through time, it's the exact same as cryo. If you get into a De Lorean and go 5 years into the future, I basically won't see you for 5 years. Same goes for freezing yourself (well, unless I go visit your icecube, I suppose ). We don't know how to thaw those folks, and my whole argument was theoretical here. Then again, we're discussing time travel .

Well, subjectively, or mentally, it's the same, yes.

But objectively, or physically, it's very different. I think the whole confusion is coming from what you admitted was an ambiguous (I'd say subtle) concept; this whole 'go' business. To put it simply, what you're referring to here is physical time, a variable and distinct property of the universe (said variability speculated by Einstein and confirmed by hundreds of experiments). In the above example, physical time is different in one example for both observers (the people and all other objects in the De Lorean see their time progress faster relative to the external viewers (and 'objects')); in the other, everybody is subject to the same rate of time relative to one another.

It's really hard to understand but I can guarantee you that discussions about mental and physical time are totally distinct and you can rarely if ever mix the two.

The whole concept of time travel is just complete and utter impossible in my opinion, there are too many paradox's that can be caused if you travelled back in time. Thats just for travelling back, if you travelled forward it would seem stupid also because if you wanted to see yourself in the future you wouldn't be able to because you would travel in a time machine to that point and you would not have progressed or even be there because you left to go to that point in time in a time machine or what not, you technically could not create a future for yourself if you are in a time machine, if you leave in the year 2007 to see yourself in the year 2020 you would not be able to see yourself because you went time travelling back in 2007 and have not come back, i don't know if that makes sense to you but the whole future thing does not really work.

Originally Posted by Xei

It's really hard to understand but I can guarantee you that discussions about mental and physical time are totally distinct and you can rarely if ever mix the two.

I understand your point and the difference. I was just saying that for practical purposes, there isn't really a difference. In both cases, when we reunite in the future, I will be older and you will have not aged a bit.

EDIT: wait, quick correction: The practical difference between the two is that, I suppose the non-physical time one might open up the possibility of traveling backwards through time. But I was talking strictly going forwards .

Lucid Seeker: I'm afraid the 'whole future thing' really does work. In a nutshell:

There aren't any paradoxes created by 'travelling' into the future.

This is one of Einstein's great discoveries; that one can travel into the future. It's been known for a century now... kinda surprising how large the lag factor is in public knowledge. ._o

It's not as simple as 'travelling' though; what we say is that everybody has their own timeline.

Relative to my timeline, your timeline can progress faster or slower.

If your timeline is travelling faster than mine, you will essentially be 'overtaking' me: travelling into the future. If your timeline is slower than mine, I overtake you; I travel into the future, relative to you.

I make my timeline progress faster than yours by travelling at a greater speed than you. However, I have to get very close to light speed even for a double in rate of time passing, and it's very hard to get close to light speed.

However, there are extremely minimal changes in rate of time at speeds which we encounter: these have been measured hundreds of times with various experiments, many simply involving atomic clocks.

Therefore, Einstein's theory (it's called relativity) and the above consequences has very very strong evidence in support of it.

Hope you understand a little more about the universe now.

Replicon; yeah, that's interesting. In fact, physical time could also flow backwards: how could you tell if it was or not? There's no reference points, time's a concept, not a solid thing.

What tends to be done is defining time's direction in terms of the direction of entropy (increasing disorder as time progresses), conciousness, and... one other, which I've forgotten. >_<

There aren't any paradoxes created by 'travelling' into the future.

But is there any way to get back?

If there isn't, why is that a paradox?

OMG if i even began to try to comprehend this concept my head would implode!!!!!

According to Einstein, time travel to the future is possible if you travel near the speed of light. But he never said it is possible to travel to the past, as far as I know. It seems like a contradictory concept. If you go back in time to the Beatles' first Ed Sullivan appearance and spray mustard on them while they are playing, you are not in the real 1964 because nobody at the Beatle's first Ed Sullivan appearance sprayed mustard on them when they were playing. You would be in a parallel reality. There is also the grandfather paradox that somebody might have already mentioned. If you go back in time and kill your grandfather before you were conceived, then you have made it where you were never born, so how was your grandfather killed? Travelling back in time is impossible.

I had watched this show on the internet about time travel. It was a bit complicated, but to sum it all up, scientists have proved that travel back in time is possible, but a bad idea. You would in essence be creating a second reality, and the original reality would not be affected, while the second one would be. So any changes you would make would not affect your family, friends, etc.

Time travel into the future is easy. Simply go just beneath the speed of light in a spaceship while orbiting around some celstial body such as the earth. The formula is something like for every second you spend at lightspeed going around the earth, 33 years pass.

Ok ok, i forgot about that observation, but surely travelling close to the speed of light or what not make time past faster for you thus you ending up the future, if you did this you could never go and see yourself at that point in time because technically you would have been travelling close to the speed of light for all those years which only seemed like a few minutes for you yourself, what i am saying is that with einsteins theory you could technically not see yourself in the future.

Originally Posted by Xei

Lucid Seeker: I'm afraid the 'whole future thing' really does work. In a nutshell:

There aren't any paradoxes created by 'travelling' into the future.

This is one of Einstein's great discoveries; that one can travel into the future. It's been known for a century now... kinda surprising how large the lag factor is in public knowledge. ._o

It's not as simple as 'travelling' though; what we say is that everybody has their own timeline.

Relative to my timeline, your timeline can progress faster or slower.

If your timeline is travelling faster than mine, you will essentially be 'overtaking' me: travelling into the future. If your timeline is slower than mine, I overtake you; I travel into the future, relative to you.

I make my timeline progress faster than yours by travelling at a greater speed than you. However, I have to get very close to light speed even for a double in rate of time passing, and it's very hard to get close to light speed.

However, there are extremely minimal changes in rate of time at speeds which we encounter: these have been measured hundreds of times with various experiments, many simply involving atomic clocks.

Therefore, Einstein's theory (it's called relativity) and the above consequences has very very strong evidence in support of it.

Hope you understand a little more about the universe now.

Replicon; yeah, that's interesting. In fact, physical time could also flow backwards: how could you tell if it was or not? There's no reference points, time's a concept, not a solid thing.

What tends to be done is defining time's direction in terms of the direction of entropy (increasing disorder as time progresses), conciousness, and... one other, which I've forgotten. >_<

Lucid Seeker; quite true, but this thread's about travelling into the future, not observing it. I also don't see how not being able to see yourself in the future is a paradox here.

But is there any way to get back?

That's really the same question as 'is time travel into the past possible?'.

I had watched this show on the internet about time travel. It was a bit complicated, but to sum it all up, scientists have proved that travel back in time is possible, but a bad idea. You would in essence be creating a second reality, and the original reality would not be affected, while the second one would be. So any changes you would make would not affect your family, friends, etc.

Time travel into the future is easy. Simply go just beneath the speed of light in a spaceship while orbiting around some celstial body such as the earth. The formula is something like for every second you spend at lightspeed going around the earth, 33 years pass.

Essentially that first bit's right, except no scientist has proved it, as you said. It may be possible if there are such things as loops in the spacetime fabric, which are not impossible in general relativity, but it is not known if such loops can form.

The second bit is not really that true though... orbiting the Earth is irrelevant (you've just gotta go fast). Also, that's not really a 'formula', and it's not correct either; basically, the closer you get to light speed, the more effect your speed has upon rate of time; diagramatically it's a curve. At light speed, the curve hits infinity; time would theoretically stop.

However, the energy needed to travel at speeds around light speed follow the same pattern; you'd need infinite energy to travel at light speed, so essentially it's impossible.

Travel to the future is quite plainly possible. I do it every hour on the hour, traveling approximately 60 minutes at a time.

Yah, and that's always gonna be true. But whose time, exactly?

If you look at it relatively, so, relative to everybody else around you who is also going at one hour per hour (weird... ) you're not travelling at all.

A car and a truck have the same velocity; relative to each other, they're not travelling anywhere.

There's no reference point other than yourself.

I use as reference a specific day in 1964, which happens not to travel in time at all. No matter what process is applied this date, it remains where it is, and I continue to move further from it.

Sure sure, I mean, relative to a stationary point in time (ie a date), we're moving forwards.

But relative to everybody else and the rest of the universe, we're moving nowhere. This is really what people mean when they talk of 'time travel'.

...but I think you already knew that anyway.

Originally Posted by ExoByte

Heres a thought:

If in the future we learn to travel back in time, why havnt we seen any body from the future in present day or in history books?

Maybe it's so that you can't interactive with past events. I'm not sure though..

A 'time machine' wouldn't be possible because of this paradox: If someone built a time machine and traveled back in time using it, someone would have given us the machine and we would have it now, no matter what time in the future it's invented.

Originally Posted by Lunalight

A 'time machine' wouldn't be possible because of this paradox: If someone built a time machine and traveled back in time using it, someone would have given us the machine and we would have it now, no matter what time in the future it's invented.

That is a really good point. Somebody would have gone back to the 20th Century or the first few years of the 21st Century if they could have. It didn't happen, as far as we know, and I'm pretty sure we would know if they had.