Time Travel

[YSSMAN]

There was a posting on here not too long ago about the 10-universe thoughts, and that was all largely to do over over the prospects of time travel, that is, if we believe that time is represented in the 4th dimension (we exist in the third).

The hard part to conceptualize is the notion of time as a line, and how one can move from one point to the other if one has not yet existed yet. In simplistic terms, it is a bit of a chicken/egg system. My personal view is that the future does not exist, only the present. Thereby we are always on that leading edge, pushing time forward as our universe speeds towards infinity. In that, with the concept of time travel, we would be able to go to any place in the past without issue, and given that the future already exists, we would thereby be able to travel back to the present, as it is only the given person who is moving about through the fabric of space and time.

...That being said, the 'Simpsons Toaster' effect must be considered, as the space-time continuum largely is effected by our actions in the past. Thereby one small move could change the entire fabric of time as we know it in our own universe. Thereby the 10 universe theory is suggested, which would thereby attempt to capture all of the possible universes based on a given event into a network of points through time.

Did that make sense?

...So yeah. I could go back and meet JFK, but if I were to tell him that he was to be killed in Texas, it could drastically alter the universe in which I had created by doing so. It doesn't mean that the universe I came from was destroyed or altered, but that I had now placed myself on another dimensional thread. As I understand it, dimensional threads cannot be crossed, so in a dimension were JFK was killed (that being ours), I could not travel to one where he had lived, or maybe to one where he was killed by a different person in a different city.

...Its all a mess...

 

[Famine]

I don't think so Famine.... I'm not sure if the analogy fits perfectly, but I've always compared that phenomena to the Doppler Effect with sound.
If you approached something at a speed near to or in excess of c, it would appear to be on Fast Forward>> to you because its light (or its time) is 'hitting' you faster than your time is passing.

Let's assume that there is an object 100 light years away from Earth. The light falling onto the Earth from that object set off 100 years before, so you are seeing the object as it was 100 years ago.

Now let's assume that I can travel towards it at 10 times the speed of light.

After 1 year I will have reached a point 90 light years away from it. The light falling on that point from the object set off 90 years before, so I am seeing the object as it was 90 years ago. Yet a year before I was seeing it as it was 100 years ago. The object has reverted to a state 10 years earlier.

Take this to its logical conclusion - after 10 years of travel I will have reached the object and can see it as it is now. The object has reverted to a state 100 years before how I perceived it to be on Earth. It has gone backwards in time 100 years in the 10 years I've been travelling.

Similarly:

I believe you got that bit right.

Another way to look at it might be to consider waves coming from some source (a thrown rock, etc) in a pool of water - assume the pool is unbounded so there is no reflection of waves.
If you move away from the source of the waves, it will take longer for the next wave in succession to hit you. If you move faster than the waves are propagating you will encounter older waves - like moving backwards in time.
If you move directly towards the source of the waves, the waves will hit you more quickly than if you had remained still - like accelerating time.

If I now turn round and look at the Earth, it is 100 light years away. The light falling on my current position set off from Earth 100 years before - I am looking at the Earth 100 years ago, despite having only set off 10 years ago. The Earth has moved backwards in time 100 years in the 10 years I have been travelling.


If I now set off back towards Earth at the same speed, I will arrive there 200 years before I left, having been travelling for 20 years. And that's Relativity.

remember last year..in math class, our teacher suddenly began talking about moving against Earth's time zones. He said "if you can move fast enough without having the Gs kill you, you may be able to travel back in time." I then said "how is that possible? Even though you are moving, time on Earth stays the same, therefore, not changing anything at all."

now....what do you guys think?

If we didn't have time zones, then yes, it would be possible (relative to the way we measure time - Relativity again). The Earth's timezones prevent this though.

If I flew at precisely the speed of night (the pace at which the light/dark boundary progresses across the Earth) with the rotation of the Earth, I'd set my clock forward an hour at each time zone, but backward a day as I crossed the International Date Line, ending up back where I started a day later. If I did it against the rotation of the Earth, I'd set my clock backward an hour at each time zone, but forward a day as I crossed the International Date Line, ending up back where I started a day later.

This applies no matter how fast you go and should be very familiar to anyone who has ever read of Phileas Fogg (or seen any number of film/TV adaptations). After all, satellites travel many hundreds of times faster and don't go backwards in time, right?


Two caveats should be added. The first is that the faster you go, the slower time goes. This is known as Relativistic Time Dilation, but is only measurably noticeable as you approach light speed. The second is that is you were to exceed the speed of light (technically only the speed of light in a vacuum - c) - the escape velocity of the universe - then yes, you could/would go back in time.

 

[Boundary Layer]

I believe we may be looking at all of this from different reference frames.

Let's assume that there is an object 100 light years away from Earth. The light falling onto the Earth from that object set off 100 years before, so you are seeing the object as it was 100 years ago.

Right, we're seeing the object as it was in the past.

Now let's assume that I can travel towards it at 10 times the speed of light.

After 1 year I will have reached a point 90 light years away from it. The light falling on that point from the object set off 90 years before, so I am seeing the object as it was 90 years ago. Yet a year before I was seeing it as it was 100 years ago. The object has reverted to a state 10 years earlier.

No sir. 90 years ago is more recent than 100 years ago. From the perspective of the traveller, the object has advanced to a state 10 years later in the 1 year they have travelled. The traveller witnesses 10 years of history in only 1 year of his time - it'd be like watching it on fast forward.

Take this to its logical conclusion - after 10 years of travel I will have reached the object and can see it as it is now. The object has reverted to a state 100 years before how I perceived it to be on Earth. It has gone backwards in time 100 years in the 10 years I've been travelling.

You're contradicting yourself. What I have underlined in your quote would suggest that we are able to see the future of an object 100 light years away from Earth - earlier in your post you've said the exact opposite.

I believe you mean to say, the traveller is viewing the object in some state 100 years before anyone on Earth will see it in that same state.
Hypothetical situation: if you left Earth today at 10c, you'd arrive on the object in 2017 (Earth time), but would not be visible there from Earth in 2017. 110 years from now, if the technology exists on Earth to focus in (extremely close) on objects 100 light years away, they would see you. Your image would be visible from Earth in 2117, therefore your image has travelled foward in time from Earth's perspective.


As I wrote above, now is more recent than 100 years ago. So from the perspective of the traveller, the object he's approaching at 10c has gone forwards in time 100 years in the 10 years they have been travelling - the traveller would see the passage of time on the object as being accelerated.

From the perspective of the object, the traveller would be seen arriving before they could be seen departing Earth. The traveller's voyage would become visible to the object in reverse chronology. In that sense the traveller moved backwards through time - his older self on the object would be able to see his younger self approaching the object (..or leaving Earth if he lived long enough on the object, I guess).



...I think any further discrepancy in our posts can be explained by adjusting the reference frame.

 

[Famine]

Hmm. I see what you're saying.

As I said earlier:

If you understand how the universe works, it's probable that you just don't know enough about it.

Same works with time travel.

 

[Tulok]

I watched that video, the little clock with the green photon made a world of difference, but i seriously doubt that this will work, wont you need a time machine in the future to travel through it? EDIT, or wont you need your time machine to travel really fast , like relativistic speed?

 

[Robin]

I watched a documentary presented by this Japaniese professor about TIME and they had this cool experiment that showed how time is altered and slows down when we are in a dangerous or thrilling situation. They had a dot matrix display attached to a guy who was going to be dropped from a great height and when he was thinking normally and on the ground the screen was flashing so fast the you could not see the numbers it was producing on the screen. However when being dropped the near death feeling sparked something in his brain (similar to a slow motion camera) and slowed the flashing rate of the screen down allowing him to see the numbers briefly... when he landed he said the numbers he saw and they were nearly correct usually getting 2/3 numbers correct each time.

I probably havent explained it very well but it was quite interesting! Basically the moral is time is made up to keep order in our lives and it is not a constant thing that stays at a steady rate like we have invented it to be... in space all sorts or wierd things distort time.

Robin

 

[Dave A]

No, time is steady, 1 second lasts exactly 1 second no matter what. The way we measure time is done so we can create order but time itself is moving at a consistent rate. When something happens and it feels like it's going slower that's just chemical reactions in your body putting you in a higher state of alertness. Time doesn't actually slow down. It's like whole time flys when your enjoying yourself, it drags when your bored thing, time isn't being altered in anyway, it's all in your head.

 

[Robin]

No, time is steady, 1 second lasts exactly 1 second no matter what. The way we measure time is done so we can create order but time itself is moving at a consistent rate. When something happens and it feels like it's going slower that's just chemical reactions in your body putting you in a higher state of alertness. Time doesn't actually slow down. It's like whole time flys when your enjoying yourself, it drags when your bored thing, time isn't being altered in anyway, it's all in your head.

Yeah, the higher state of alertness created by chemicals is what probably allows you eyes to read a faster flashing rate or react quicker (like the example I gave in my previous post) which it why you see things that you wouldnt ordinarily see at a resting state of mind.

I think it my previous post I must have got somthing mixed up I saw it ages ago!

Hmmm... Time is a funny thing!

 

[Danoff]

The whole speed of light thing is tricky, but from what I understand you're not actually going back in time when you move faster than C, it just looks like it if you look backward. It looks like you're going forward in time if you look forward.

Objects A and B are 10 light years away.

You start at A and travel toward B.

When you start, you're watching light from B that happened 10 years ago. And the light from A is current.

When you arrive at B you're seeing light from A that happened 10 years ago, and the light from B is current.

So if you travel between A and B in say, 1 minute, during that minute you watch ten years of events in reverse on A, and you watch ten years of events in fast-forward on object B.

Once you arrive at B, if you turn around and go home you'll see the opposite. A will appear to advance 10 years back to it's original state, and B will appear to revert 10 years back it where you saw it when you left (or two minutes after it was when you first left A to be exact).

Now, don't ask me how long the trip felt like it took to the person moving between the two objects. And don't ask me what the spaceship looked like to the people on A and B... because that's where this gets really tricky. If I remember correctly, it looks like the spaceship had traveled at th speed of light for two minutes and was still headed away from A when you arrive back at A suddenly. You could then watch your trip to B and back from A for the next 20 years.

Or something like that.

 

[wfooshee]

I think my head hurts, but I'm not sure. I think I saw myself leaving the room I just entered, but I don't know if that was me when I left a while ago before I came back, or if it will be me when I leave in a couple of minutes.

Isn't beer great?

Time travel with lightspeed tricks is cheating. You need a real H.G. Wells machine, with dials and stuff you can set for your desired target age. Uncollapse all those extra dimensions and it should be easy!

 

[Touring Mars]

About traveling into the future, i believe that there is a better chance then travelling back in time.
But here again my question! I can't imagine travelling forward in time and see people living in year...2020.
In time travelling i understand that like you take an aerocraft which flies faster then the speed of light and when you come back to earth, time passed by like 10 years, but for you in the spacecraft only 1 year. thats how you "safe" 9 years of your life and so you can live 9 years longer then if you wouldnt have done that trip.
To see people living in 2020 there has to be another world for that. Since there is only 1 world, how would you be able to live in 2020...Thats just what i dont understand :s

http://en.wikipedia.org/wiki/Time_travel

Chris

Thanks to a physics experiment that went wrong, I actually time-travelled to the year 2020 and trust me, it isn't worth it. A pandemic hits and basically destroys the world economy...

In fact, I would go as far to say that you should actively seek out a time machine and hope that you can miss out 2020 altogether, either by travelling back to now (or earlier) or spin forward to 2030, by which time the global economy may have almost recovered.

Also,

Spoiler

Kimi wins his only F1 world title this year, but by 2020 Lewis Hamilton is a 6-time world champion... oh, and Donald 🤬 Trump is the President of the USA

 

[DustDriver]

Going back to the age of dinosaurs isn't an option. The minute you sneeze all the dinosaurs would die

And i would want to go watch some historic battles, or maybe the library of alexandria, or rome in it's full glory, or Carthage, or other mayor cities in the old times. (maybe watch how the pyramids have been build)

 

[Touring Mars]

That's the thing about time travel, though... time travelling doesn't spontaneously teach you how to speak Imperial Roman... and the minute you brandish your little book of '101 Handy Roman Expressions' to ask directions to the nearest public convenience, you'd be arrested by a centurion on suspicion of witchcraft, blasphemy or associated skullduggery and hanged upside down in a dungeon for 25 years, then crucified (if it was a first offence, and you had a smart lawyer).

 

[DustDriver]

Just learn up front to say: i'm a god, kneel.
Remember to bring a gun of some sort to prove it

 

[Dave A]

And what if they don't beleive you, shoot someone and wipe out an entire family tree from the future, possibly wiping out other family tree's in the process maybe including your own.

 

[DustDriver]

now that's why it isn't possible to time travel.
Even being there and doing nothing effects the future.

 

[Sureboss]

This is potentially a much riskier issue - without the benefit of a steerable machine (and let's face it, that's not going to be easily done any time soon).

Quite, the Yanks have struggled enough to get cars to steer!

 

[wfooshee]

. . . .

But Key Question 2 is, for me, a trickier issue, and that is WHERE will you end up? This is potentially a much riskier issue - without the benefit of a steerable machine (and let's face it, that's not going to be easily done any time soon), you might just say "I want to be transported back in time 200 years to this same, exact spot I'm standing on now." OK, that's fine, chances are you'd land in a field or up in some trees. But what about a millions of years ago? Chances are you'd end up in the ocean, or in a swamp or a volcanic flow... it would be fraught with danger. And would it even be possible to re-appear in exactly the same point? I highly doubt it, since going back in time would mean that the universe would be ever-so-slightly smaller than it was from the point when you set off. Your 3D location in the world right now simply doesn't exist in the same form in the past... you may even end up floating in space, at a point where the Earth exists now, but back in time was a billion kilometers away (I hate it when that happens! )

That's something I've always wondered about; why don't you see it addressed by any of the writers? Probably because it's beyond solution, so we just ignore it for the story's sake. But you can't even go back a single second and be at the same place you started. What with the Earth's spin, its orbit around the sun, the sun's path through the galaxy, the galaxy's motion through the Universe. . . . Oh, my head hurts again!

 

[Citrus]

My theory is..... If it is possible to travel in time... would you age as well? Say you were 30 now (2007)... if you traveled back to 1997, would you turn 20 years old again? Im thinking it could go either way.

30 - 30
2007 - 1997

or....

30 - 20
2007 - 1997

or the other way...

30 - 30
2007 - 2017

or....

30 - 40
2007 - 2017

If you aged as well, this could make it impossible to travel back or foward in time before you were born or after you died in the future. What do you think?

 

[Dave A]

I don't see how travelling in time should affect your age since you by means of travelling back in time with your "time machine" would be manipulating time and it's effects.

 

[MisterWeary]

Traveling back in time is a concept that could very easily be proven if the whole world could unite...come with me on a magical journey...

Lets say the majority of the planet's population agreed (and knew) that whenever (or if ever) time travel is invented (and perfected) then someone or something returns to a set point determined by some world governing authority...lets say 20:00 GMT Wednesday 27th June 2007 at the base of Big Ben in London. Everybody on the planet is forced to remember this date and time and should time travel ever become possible in the future then the people responsible return to the point and place in time that was agreed upon.

Technically...if time travel is ever invented then something should happen at 20:00 GMT on Wednesday the 27th June 2007 at the base of Big Ben in London? There's plenty of reasons why nothing would happen, like civilization forgetting about the date/time/place agreed upon, maybe time travel of actual objects is never possible, but TECHNICALLY...this would prove it?!?

 

[Orion]

You can always win the Lottery with Time Travel.

 

[Danoff]

But Key Question 2 is, for me, a trickier issue, and that is WHERE will you end up? This is potentially a much riskier issue - without the benefit of a steerable machine (and let's face it, that's not going to be easily done any time soon), you might just say "I want to be transported back in time 200 years to this same, exact spot I'm standing on now." OK, that's fine, chances are you'd land in a field or up in some trees. But what about a millions of years ago? Chances are you'd end up in the ocean, or in a swamp or a volcanic flow... it would be fraught with danger. And would it even be possible to re-appear in exactly the same point? I highly doubt it, since going back in time would mean that the universe would be ever-so-slightly smaller than it was from the point when you set off. Your 3D location in the world right now simply doesn't exist in the same form in the past... you may even end up floating in space, at a point where the Earth exists now, but back in time was a billion kilometers away (I hate it when that happens! )

It's a good question, and a fairly difficult one to answer. I'd say that the answer to it depends on where you are during the time travel process. Do you still exist on the planet governed by the laws of gravity etc.? If so, you can stay in the same spot during your time travel because gravity keeps you glued to the earth. If that's the case, though, your craft is probably susceptible to all kinds of interference from the outside world - unless you invented some sort of force field or something that would bubble you off from the rest of the world.

And how would the folks in the time periods you were passing through see you? If you were in a force field perhaps they wouldn't? Or they'd see the field. But if you weren't, you'd just look like some dude who was moving really really slowly... backward.

If that was the case I think the impulse to poke you with a stick would be irresistable. What you would see from within your time travel machine is that suddenly there are dozens of children surrounding you all poking you impossibly fast with sticks.

But, as you say, these sorts of interactions with the time periods you pass through are required if you're going to stay on the earth. Because if you go to some other sort of dimension it's going to be tricky to get where you intend.

Hmm....

Perhaps if you could give it some sort of universe centered coordinates specifying a particular spot on the earth. You'd need a good earth/solar/galactic ephemeris, a map of plate tectonics over time, and an accurate knowledge of geological changes.

You'd also want to make sure that you and your time machine took the place of whatever it is that exists at that specific place on the planet. Because if there's a tree growing at the spot you specify, you want to make sure you take precedence of the tree.... of course... that wouldn't stop the bit above you from falling on top of you.

Lots of practical problems here.

 

[dylansan]

If you understand how the universe works, it's probable that you just don't know enough about it.

Same works with time travel.

Let's look at it this way - time is just another dimension. If you can travel in length, width and height, why not time? In fact, you're doing it right now - travelling forwards in time...

That reminds me... is it possible to have gravity in the dimension of time? After a very long time, could we slow down and reverse in time? We probably wouldn't notice though because we remember what happened backwards in time, no matter what direction we actually move in.

 

[Touring Mars]

You can always win the Lottery with Time Travel.

I doubt you could... by going back in time, you'd alter the future, so the lottery result that you had memorised and bought a ticket for would probably not happen again. Cool if it did though, but knowing my luck, I'd probably still only win a tenner

Lots of practical problems here.

Fo shizzle.

could we slow down and reverse in time?

Slowing down time could be a very bad idea indeed. Imagine being able to see everything happening at a billion times slower. Every second would feel like 30 years. I'm not sure we could 'reverse' time, since the closer you got to stopping time, the longer everything would take until every instant lasted for an eternity - almost like watching 'Big Brother'

 

[djblackmon]

This is a very interesting subject, just wish I knew more about it. (Well I did learn from people posting)

But here is something I was thinking about last night while reading through this thread:

Lets say you get into a car crash today, and you become a parapeligic. 10 years later, time travel is created and perfected. You know go to the past on the same day you crashed, and stop yourself from crashing. Do you just suddenly become able to walk, and lose all memories of being a parapeligic, or do you dissapear, and there is a new you in the future ???

And to add to the where would you end up idea:
Since the Earth follows the same axis, and spins at the same rate, if you go back to the same exact day, same exact time, and say 10 years ago, wouldnt you end up at the same place?

 

[Famine]

And to add to the where would you end up idea:
Since the Earth follows the same axis, and spins at the same rate, if you go back to the same exact day, same exact time, and say 10 years ago, wouldnt you end up at the same place?

No - since it doesn't. There's eccentricities in all of these factors.

 

[Casio]

Has anyone seen the movie 'Primer', it's all about Time Travel, but amazingly hard to understand.

 

[MisterWeary]

Primer is such a cool movie, had to watch it three times to come close to understanding it

 

[Azuremen]

Famine and Boundary have the most of the technical details correct, from a science standpoint. Though Famine, you did get own at one part there.

I do however agree with the though that if you left an object traveling at a speed greater than C, you would see it "rewind" so to speak.

Touring Mars, going back in time so far would present a problem of you breathing, so showing off to the locals might just get you killed because they think you are a demon because of a helmet. Why trouble breathing? The atmosphere does change gradually over time, and we are a bit more use to elevated levels of CO2 and such.

Folding space/time would be the best option for time travel. Since its already shown gravity distorting space also distorts time, this makes the most sense to me for how to get around to traveling through time. Just fold time in half like a piece of paper.

The bigger problem is in paradoxical situations, which is where everyone has trouble and gets hung up. Not sure their is any clear cut answer on it... except creation of alternate time lines that reflect these changes. The Primer thing kinda shows that, in a way.