I know I may be posting some dumb founed topics, but I am only 15 and Im just now trying to get into the scientific world. Now for my question....

Base on what is certain,

If someone was to come back from the future to your time, or, if you went back to the past to someone else time. Would events that take place alter your present?

Example.

I have to be politicly correct about this though cause I may be a pshyco......?????? (extreme sarcasm)

I go back in time and get rid of my grandma. I then jump back to the present day.

What would the effects have on my life now?

Would it alter my timeline, or would my journey back create a seperate alternate timeline where my actual timeline and the new one I have created split? If so, Would I return to my original timeline or to the new alternate time line?

Im really baffled by this and Time Travel in general. I know there are some very intelligent people out there so will one of you please help me out on this.

well....

I think you would come back and be arrested for killin' your grandma :)

But there's a little problem with the present-changing-thing.

When you travel in time with a sort of machine or at least some help, and in the past you change your present.
Will your help in the present still be there???

When you kill your grandma and you get arrested, you won't be able to make your time-machine, so you can't return in your changed present.

Do I make myself clear or is it too weird?

Jagdwuf...

There are speculations that there may be an infinite number of universes, diverging at every instant a decision is made, or an event could have a different outcome. This seems bogus to me, since the number of possibilities in any instant, universe wide, is way beyond imagining. However, if it were true, you simply would return to one (or several) of those alternatives caused by your action in the past. More likely, if you could go back and change the past, you have done it and have caused this present for yourself.

My theory is that when you go back in time you can't change anything but you are a observer of the past.

Originally posted by Shinigami
My theory is that when you go back in time you can't change anything but you are a observer of the past.

We were talking about time-travel physically, in what kind of circumstances do you think we'll be in the past, when we only can observe???

If we shoot somebody in the past we just have to change the present don't we? What makes us stop pulling the tricker?

Hi KneD,


What makes us stop pulling the trigger?

For a mentally sane person, his/her conscience :D.

Bye!

Crisp

For a mentally sane person, his/her conscience
indeed, but is someone who travels through time mentally sane???
I don't think so......

Hi KneD,

I first smiled when reading your post, but then I realized there's actually a very good point there. Why would anyone travel back in time anyway ?

To see yourself get born ? Take the homevideo!
To witness the crusades ? Take a history book!
To see the dinosaurs ? Do you really want to be amongst them ?

Or is it to...
Take some items there and sell them in this age as antique stuff ?
Go and get gold/precious metals in the stone age and use them here ?
Change history by introducing knowledge we have now in 1500 ?

Would any of these things be a good idea anyway ?

Bye!

Crisp

not one of your examples makes any sense to me indeed.
But maybe from a scientific view???

I can imagine that people finally want to know how the pyramids are build.

But go back to a time we know enough about, why should you???

Selling old stuff makes no sense either, if you want to get rich, just sell your time-machine, it's much easier and it makes much more money.
Change history is stupid, a big change you can't return. (see my earlier post)
And about the home-video, who wants to see a birth anyway??? at least I don't :)

Too much TV physics here!

I have to assume that conservation of mass/energy does not change when time travel physics is applied. This means that if you "move" chronologically, you'll have to have the same momentum throughout the ordeal.

Earth rotates, earth orbits around the sun, the sun moves around the galaxy, blah, blah, blah. If time travel really was possible, and you go back to see your grandma, well, you definitely won't appear anywhere near the solar system. (I am assuming that we're not at the center of the universe, and that we have lots of momentum...)

In order to get anywhere near your grandma as you time travel, the time traveller must have one of those made-for-TV starships to fly back to Earth. The point about shooting anyone seems moot.

We should realise that if we are able to travel in space, it must be not so difficult to travel to earth as it seems now.

(welcome aboard yupa)

So you're saying that you see no problem with the point I just made, about how we can't throw out basic principles of physics when time travel ones are developed?

What I tried to point out in my last posting is the difficulty in knowing where you'll end up when time travelling...To go back 30
years, it is not improbable that you may end up several light-years away from your target. Then travelling at near-lightspeed to home will result in your arrival many, many years after you started.

Then, from several lightyears away, Grandma and everyone else you know will die before you could get back.

Perhaps I erred in posting about "is it possible to do what Jagdwuf suggested", rather than "what happens if it were done..."

Thanks for the welcome.

We should be able to travel faster than our milky way, then we can get back on earth before we are in the 21st century again;

We travel to the year 1950, we travel just a little faster than our mikly way/solar system and we are back on earth in the year 2000.

The problem is that we can't say the speed we travel through space with our milky way, it is relative.
We can see how fast we travel inside our cluster, but maybe our whole universe is moving???

But where you didn't thought of Yupa is that when we go to that place in history and end up at another location (where earth first used to be) then it takes a long time to get there, you can't travel faster then light speed!!!!
So when we can travel that fast, we can travel that fast back too....so when we indeed end at an elderly location, there is no problem coming back.

You would have created an alternative timepath. You have many parallell lives already, alternative yous. So if you die in one of the alternative lives,or kill your grandmother, the rest of them will not see much difference, maybe a slight fluctuation, as a sickness or personal chrisis in the othere lives. You will return to the life you knew as yours before the incident happened. You will not continue to exist in the same reality where you have killed your grandmother, before she gave birth to your mother, or father. Probably a memory of the incident will be left, and you will become more aware of your other existences.

sorry, but I think your opinion is nonsense, but who am I....??
everything's possible.

But I'm just a little to realistic-thinking to believe in this kind of stuff....

And try not to refer to others opinions as nonsense. :)

Although KneD may have been a bit less blunt with a lovely scatter-brain such as yourself, I do think he has a good reason to reject what you proposed.

As I understand you, an 'event' causes an alternate and parallel time line to be created. Were this to be the case, is it only someone from another time period who can trigger such an event? And if not, what are the parameters that must be met?

Example: If I step on an ant, am I creating a parallel time line in which the ant has not been stepped on?

Please explain.;)

Hi KneD,

In your last post, paragraphs 1,2 does not take into account the possible effects of near-light speeds. I agree with paragraph 3, and you missed the main idea of my first post in your 4th paragraph.

Let's try an example.

Suppose Earth rotates around its axis and has no other motion, and that no other celestial object moves. You are standing in a room at the equator when you activate the time machine, set to jump back 12 hours. Where will you be standing?

What I've suggested is that the room and the time machine must be halfway around the world. You didn't move, and you are on Earth as it was at that time. The only idea in paragraph 4 that I agreed with is the no-faster-than-light (FTL) one. If you ended up in any other location, then not only will you have time-traveled, you would have teleported or gone FTL...Since there are threads on these topics, I won't talk about it here.

Now let's add in the motion of earth's orbit, and the motion of all celestial objects to my example. You won't be on Earth after a time jump and quite possibly very far away. Get the idea?

I completely agree with you.

And I already got the idea, maybe it was a little confusing post from me, but what I was trying to say in the 4th paragraph is:

The problem of travelling back to earth in space is the same problem as the travelling from earth to that place in time/space.
That's the speed of light.

(I think we are on the same point of view yupa...)

But yesterday when I was trying to get some sleep, another idea came up in my mind:

When you travel back in time in 2001, and you end up in 1950 but on the location where earth was in 2001.
And earth will be at his location from 1950.

That will be great!!! When we consider that earth moves the same way again, and we travel towards it then we don't have to have such a high speed to be on earth before 2001.
Actually when we don't move, we will be on the same place on earth again in 2001.
When we travel towards earth then we will be there before 2001!!!!

And another point: while transporting to the past, we don't have to deal with the speed of light part, we don't move in space!!!
(but earth does, is that a trouble?? hmmm)

Are created all the time. As in the "ant-incident" and in any incident and event. Everytime there is a choice involved, and that means pretty much all the time.I do agree to being lovely, but certainly not a scatter-brain. I reject such remarks on my personality. Maybe my ideas seem strange and confused for those who have never heard of them before, but If you read with an open mind, then maybe even you will recognize the logical pattern in my reasoning too. Personally I never dismiss anybody as less intelligent, just because I do not agree.

I am more confused than ever. Here is my question:

You have a time machine. You get a pound of gold. You put it on the table. Then 10 minutes later you put it in the time machine and send it back ten minutes. Does this mean that at (T-10) minutes you see two pounds of gold?

Irrespective of whatever time line you are talking about, you will have two pounds of gold, correct? And if you keep repeating it, then soon you will have a ton of gold.

That means, you are creating matter out of nothing, or did I miss something here?

Hi kmguru,

Good one, I think you've just added another example to the "paradoxes with timetravel" list! With that reasoning you could - as a thought experiment - double the universe's mass if you'd just transfer enough matter, indeed violating the conservation of matter/energy.

Bye!

Crisp

Hi Crisp:

Thank you for agreeing with me. My opinion on time travel is like perpetual machine, impossible because it violates the most fundamental and easy to understand rule of the Universe.

In the past, people came up with an excuse that time will branch out and hence no paradox. It is the same story with perpetual machine that the machine will draw energy from the universe.

In my example, time branch excuse does not work.

Thanks.

Well, this is very complicated, I agree, and we can never be certain until we have actually tried it. But I believe that an alternative reality is created everytime you intend to break the time, and therefore you will never see the gold you send back, because you, who you are in that particular instant , is not the same you that exists 10 minutes back in time. So if you send the gold back, you will loose it completely. The same goes if you try to send gold to the future.

Let's use the gold example:

I think that if you put the 10 cm next to the 'old' gold, then the 'old' gold will dissapear, you will only have the gold that you transported.

I know it sounds a little stupid, and in the gold example it is a little strange.
But when we think of transporting human through time, we never speak about another 'double' people.
I won't meet myself in 1999 I think, I will be myself again.
So the gold won't be duplicated....

I wondered about that too, and the more I think the more I come to the conclusion that you will actually meet yourself in the future, the future you, not you as you are now, but a different future you. Because you, as you are now, will always be in the present of your present reality, and if you go to another present by braking through time, you will meet another version of a possible future self. But then, you could also become yourself, just as the gold would become itself.

Hi KneD, Bebelina,

The idea is the following: you have a room where you have one bar of gold, and a timemachine. The bar of gold is on a table at 10 am. You sit nicely in a chair. This is a static situation. No way you turn it, at 10 am on that day you are sitting in chair, staring at a bar of gold that lies on the table - you cannot change the past by an action in the future. We'll call this copy of you "You@10:00am".

At 10:10am you, who we now call "You@10:10am" take the bar of gold and travel back in time to 10 am with the goldbar in your hand. You arrive, just to see You@10:00am sitting in that chair, staring at that bar of gold. The freshly arrived You@10:10am puts the goldbar next to the one on the table.

At that very instant, You@10:10am has two gold bars where You@10:00am only had one.

Now comes the tricky part, the part of "seperate timelines" (and we're going highly hypothetical here, let me remind you ;)). If there would only be ONE timeline, then there would be a contradiction, since the You@10:00am will travel back in time at 10:10am, becoming You@10:10am. But since You@10:10am already travelled back in time, there would suddenly be two You@10:10am's at 10:00am (okay, this starts to get confusing :)). This proces repeats itself ad infinitum, but since there's only one timeline, all processes have to take place. This means that at 10:00am, all of the sudden an infinite number of You@10:10am's would pop up having a new gold bar in their hands. This simply sounds absolutely absurd so we are lead to think that timelines seperate at the moment a decision is made.

Now this scenario has a problem aswel: the moment the timeline seperates/branches from the original timeline is when You@10:10am arrives at 10am after the timetravel. At that moment a new timeline has to be created to prevent the problem mentioned above. In our example this means that You@10:00am sees You@10:10am arrive and has two choices: You@10:00am can choose to travel back in time at 10:10, leading to two You@10:10am's travelled back in total, adding another branchline, ... proces repeats... yedda yedda... Or he can choose not to travel back in time, leaving just You@10:10am and the original You@10:00am at 10:11 (since nobody travelled back in this timeline - this is starting to sound like a cheap SciFi show you know ;)).

The later scenario leads to another problem, being that you've introduced new mass into the universe@10:00am... Instead of a bar of gold, you could also decide to transport the entire universe back in time (thought experiment), - kinda violating the principle of conservation of mass/energy.

Now I can hear you argue: "but perhaps these laws aren't valid for timetravel", well, then you can't timetravel at all since if one law breaks down, then why shouldn't all the others ?

Conclusion: timetravel might not be possible after all.

Bye!

Crisp

Thank you Crisp for explaining that to our readers, I could not have done any better. Here is another monkey wrench you might want to add. Just in case someone will complain about sending someone or the gold back to exactly 10:00 am, let us send each time to T plus 1 millisecond(T being the last time transfer). So every millisecond one guy pops up with one gold bar or if the time machine is big enough a BMW....

Or instead of the guy, we could send Bebelina. In short order we will have a planet full of beautiful Bebelinas.....and name our planet the Eve Planet....(I am kidding Bebelina....)

Now the guys are thinking...where can I get one of these machines.....

I remember an episode of old Star Trek involving an Eve Planet...? :p

I'm 14 and I found this forum. It looks cool This is my first post so don't criticize me if I'm wrong. I read in an article in discover magazine about how he thinks that alternate universes with copies of us exists. If this is true then when you time travel you would be in fact traveling to another world and altering that one instead. Even if you gave Shakespeare his plays (the example they use in the article) they still would have been by Shakespeare in another reality. Then again I didn't really understand the article all that well.

Welcome to sciforums free_thinker. Alternate universe, many dimensions, time travel are wild ideas that should keep your mind open for possibilities. Who knows someday you may find something that have practical applications...

coming back to "could time travel to the past alter it?" i know that i have supported this paradox before in another thread, but i find that it makes a lot of sense...maybe not when i explain it, but just to think about its meaning. this would be the grandmother paradox. One may pose the question "what if you went back in time and killed your grandmother before she gave birth to your mother?" the problem this would create would be that if you have killed your grandmother, then your mother would have never been born, and going further yet- you never would have been born. yet, if you were never born you couldn't possibly have gone back in time and been able to kill your grandmother. this same thing applies to the fact that what has happened happened and will not change. when you travel back in time you become part of the past as well as the present time which you came from. If you were to travel back in time and cross your own world line you could shake hands with a younger version of yourself. this younger version of yourself would eventually come to the point in time where you will travel back in time and shake hands with a younger version of yourself continuing a cirlce through time. there is no real beginning to the cycle and no end. one could also apply this to the sinking of the titanic. you could travel back and try to warn the captain of the ship that he was going to hit an iceberg. this attempt would be ignored because obvioulsy the ship has already crashed in the past and your attempts failed then, the same as they will now, but you are only just now aware of your time travel to the past since you have been living in the present and not your future. according to these theories, it is physically impossible for someone to change the past through time travel. my explanations are very poor, but i hope that someone can pick through them enough to understand the main idea.

Looking at the facts you have to take into consideration the "Schrodinger's Cat Experiment", after all the experiment involves an understanding that the cat in a box becomes a multiversal victim of foul play, either with a universal tampering where the cat lives or "Murder" where the cat dies.

This led me to think two possible conclusions:

1: when you create a parallel from one world, all the energy within it does't actually double, it motions towards the one with a higher quanta level atomically (Thus creating your perceptional world, and making the other parallel unseen from your observation position)

2: As Kmguru mentioned in another topic and has been written within the book "The Holographic Universe by David Deutsch".
Parallels when created split the universal quanta into a fraction of the number of parallels that are created. This would of course mean any studies into the smallest quanta of an atom would be of little use since they will just be a decimal place further in a measurable scale ad the quanta itself would be more like a holographic fractal.

(This when added to my conclusion of atoms being created from photon acceleration through gravity pockets would tie it together.
In english: If a blackhole exists and light from stars accumilates at it's mouth, the light accelerates to the narrow-end of a funnel where it becomes an Energy packet from its spin. This would conclude why their is a photoelectric effect.)

****

If the first assumption is correct, then some universe somewhere is going to lose it's piles of gold. If the second assumption is correct then you wouldn't need the gold to begin with you could just make it out of light.:p

when ever someone goes into the past its nearly always to kill there gran (poor thing).
anyways, time traveling is to take into account the following
1.time travel is possible
2.when you travel into the past, which past is it you go into?
3.is there one time line or is there infinite possibilities at any instant in time (if one time line, 2 doesn't apply
4.when reaching the past where or what is the further (home where you left from)
thus at any instant in time, there must be a place, a time, a space time were you are. like a cosmic pointer.
5.like the stepping on the ant example, there are infinite possibilities (could have missed), which direction do our self follow, how do we know if we are who we were,before the disesion?
i tend to belive that there are infinite possibillities, and that time is not in a line, but in a circle (quantum theory).
these are just a few thoughts i have while reading through the whole of this form. feel free to disagree

-sorry about the spelling

Put it this way: Time travel is impossible. Simple.

To develop your own opinion, read up on it. There are many good books that deal with the subject.
Or try these:
http://directory.google.com/Top/Science/Physics/Relativity/Time_Travel/

http://directory.google.com/Top/Science/Physics/Alternative/

Im a friend of oggie im borrowing his name to give my views. If u went back in time and altered it in some way my personal belief is that such an action could thoretically permantly disrupte the time/space contiuium forceing it to collaspe in opon itself resulting in another “bigbang” and stsrting over again,a time loop if u will.
This throey ignore ths possibiltys of paerell universer (which might also happen) to concentrate on the fact that space time cannot(in my view) be tampered with becauase if it was such playing with time must of already happened beforre hand in order to maitain spacetime cohosion which again creates a loop.

I remember thinking the same thing a few years ago. But I came to the conclusion that if you altered the timeline in the past it violates relativity. I don't remember exactly how I came to that conclusion though. Something about when you go back in time, the timeline is altered, so the effect alters the timeline at the speed of light, correcting everything. I don't remember where, but there's a contradiction in there.

I did kind of mention this as a hypothesis.


When you create a parallel from one world, all the energy within it doesn't actually double, it motions towards the one with a higher quanta level atomically (Thus creating your perceptional world, and making the other parallel unseen from your observation position)


I of course didn't broaden upon it, or write it in a way that might seem legible.

If you went back and created a difference, you would create a parallel, all the quanta within that world is infused with quantum entangement. All quanta is positioned with regard to the forces around it. When you make a change those forces move (although there would be a world somewhere that was ghosted with the original timelines forces in their position).

Since the parallel/timeline/world you exist in has "stronger" more relevant forces, your world follows those forces ruling in comparison to that of the original timeline.

(If you existed on the original timeline, you would be following it's global forces in comparison to that of the now ghosted parallel.)

This is why parallels don't merge. (Unless there is a frequency fluctuation but this would make more sense if you studied the "Schrodingers Cat Experiment". This is when you create a MULTIWORLDS OBSERVATION, where something can be viewed from one but exist in the other.)

When we go back in time and change the past, at that instant, another quantum universe opens up and time splits into two parts with each one leading to a new universe. So if we go back in time and change something, the universe we came from will stay unaltered (Our past cannot be altered). We merely changed the future in some other quantum parallel universe.

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It would appear logical ... if time travel to the past were possible.

Interesting aspect though: 'You', as the time traveler, would then be bound
to the new 'time line' since in 'your' past, the change occurred.

Most interesting. "You can't go home again" takes on a new meaning.

Take care. ;)