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EvilEye
2008-Sep-21, 04:58 AM
First of all, let me start out saying that I am not EvilEye. I am his son, Brandon.
I am fourteen, in 9th grade, and am in all Honors classes. I asked my dad's opinion on this question. :wall: That was a BAD idea. I did not get the impression that he understood me.
So, here it is.
Assume you are in the future. Wormholes and time travel are obtainable, though only available to the top scientists. You happen :whistle: to be one.You have access to a machine which creates a wormhole that can also warp time to your liking. Don't ask how. Communication is faster than light as of this future. In fact, communication is instantaneous.
You decide to go back in time one year to a planet which is completely uninhabited about thirty-four light years away. You bring with you a couch. Why a couch? Well, it is really ugly, and you wanted to get rid of it anyway. Besides that, it could be no easier to pick out against the landscape, making your experiment just that much less complicated.
You have also put many instant transmitters in the couch.
When you come back, you check your computer for the transmission signals from the couch. :hand: But, before doing that, you return to the world through a same-time wormhole and see the couch five feet in front of you. You are now sure it is still there. Using a hand-held device, you check every transmitter to be sure they all still work. They do. :)
You return through the wormhole. NOW you check the computer for the transmissions. My question lies here....

Now I am not doubting that the transmissions would still be instant, what I don't understand is if you would recieve the transmissions or not. I am wondering, if you changed the space-time continuum (using a variable which should not affect the future in any unforeseen way for safety reasons) would that change instantaneously rewrite the entirety of the continuum? OR... would the change travel outward in a sphere at the speed of light; thus making a sphere of an alternate timeline which would constantly expand at, once again, the speed of light until it consumes every last tiny piece of the universe. :doh:

For anybody who I lost somewhere along the way, (Points at own dad who could only come up with the conclusion of my question being incorrect...), think of it like this.
You take a piece of the fabric of the space-time continuum. Imagine it is an actual fabric. The question I pose is this. Would changing an event somewhere around the middle be like changing the color of the thread from then on? Or would it be comparable to spilling a dye on the fabric; the dye then radiating out through space and forward through time?:think:

In all honesty, I thought this one up on the bus ride to school one morning. It has plauged me ever since because I would never be able to find out.:boohoo:

If you vote for an answer, and you have ANY imput beyond that answer, please post anyway!

(P.S. My dad told me that there was a spell check in here, and I cannot find it. Sorry for the typos.)

(If there are any! :p )

Neverfly
2008-Sep-21, 05:57 AM
I'm suddenly reminded of Capt. Janeway...

Simply put, if you traveled back in time and changed something, then that change was not made in the past. It was made in the present.

You made the question much more complicated than it needed to be.

The "continuum" and "Timeline" stuff is good wording for Sci Fi to make it sound all fancy- and that's about all it's good for.

Imagine standing on a river bank. You look at the water.
Then you send a clone back in time to stand 100 yards away and drop a piece of styrofoam in the river.
You will see the styrofoam float by. The river did not change.
Consider time like that river.

WaxRubiks
2008-Sep-21, 08:48 AM
I don't know why you're asking on here, Brandon, this is the "David Hasselhoff appreciation society forum", your father is a much appreciated long term member...:D

G O R T
2008-Sep-21, 10:28 AM
I agree with Neverfly.

If you put a beacon on the couch a year ago you would get the signal before you left to do it. This logic works fine in your hypothetical universe, but the question is wrong in ours.

BTW, you get an A in english language skills.:) So rare these days.:(

astromark
2008-Sep-21, 11:16 AM
In order for me to answer your posting I would need to imagine that instant is a possible fact. It can never be. When you make that leap of fact to fiction you can have anything you like... But given all you say as fact then ... You might be able to break the laws of reality, but the rest of this universe is stuck with C as the velocity that can not be attained or exceeded. if you got home before the light speed image arrives then no. The lamp does not yet shine.

EvilEye
2008-Sep-21, 12:27 PM
Exactly what I tried to tell him. At least he's thinking.

I would have had him post in the ATM section, but feared he would get weird answers.

Thanks so far.... looking forward to more.
EE

Ken G
2008-Sep-21, 02:21 PM
First of all, let me say that all questions in science are inherently experimental questions, so no definitive answer can exist for your question in the absence of an experiment that actually meets its general attributes. A theory can be thought of as a way to connect all the various experiments that share a certain set of general attributes, but it cannot be thought of as a way to determine in advance the result of an experiment that includes fundamentally new attributes about which we know nothing-- as yours seems to. So all I can do is give my opinion, based on experiments that have been done. The experiments that have been done always show that the effects of causation are much like the spreading dye in your question, so I chose that answer.

However, I think your question is really asking, would that picture still hold if we include two fundamentally new things, time travel and instantaneous communication (the latter turns out to not even be easy to define, let alone carry out). But those two fundamentally new things bring us into a realm of experiment that has not only never been done, but seems quite likely to be fundamentally impossible. So that's why you are also getting quite a few of the last answer to the poll. Ultimately, we'll never know until such a time as we can actually do the experiment, and that might be never.

Jeff Root
2008-Sep-21, 02:35 PM
This is all about "What if?" The ATM board isn't very good with "What ifs".

Brandon,

The "What if?" in this case is basically "What if time travel was possible?"
What I think would happen is that next week, three older yous, from three
different times in the future, show up in your home on a day when you
would otherwise be alone. (You all know that because your dad was out
for most of the day and nobody came to the door, so the future yous
know it was a good day to get together, and you of course kept a record
of the date and time for your little reunion, so that you wouldn't forget.
One of your future yous gave you that record, so you'd never have to
actually create it.)

The future yous give you a time-travel machine and explain to you how
to use it safely. They also tell you much of what you will be doing for
the rest of your life, and will provide you with information that will help
you in your time travels. Also some cash for expenses and investment.
Since they know exactly what to invest in, the few hundred thousand
dollars they give you will make you a billionaire by the time you are 18.
The cash for expenses is of a variety of kinds from various eras, past
and future.

Your future yous also explain to you how to use the time machine to
obtain as many more time machines as you want from the future. They
can tell you how many times you will do that, of course, since they will
already have done it.

Your future yous will likely know how, where, and when you will die.
I wonder if they will tell you.

-- Jeff, in Minneapolis

mugaliens
2008-Sep-21, 03:20 PM
I am wondering, if you changed the space-time continuum (using a variable which should not affect the future in any unforeseen way for safety reasons) would that change instantaneously rewrite the entirety of the continuum? OR... would the change travel outward in a sphere at the speed of light; thus making a sphere of an alternate timeline which would constantly expand at, once again, the speed of light until it consumes every last tiny piece of the universe. :doh:

This is sort of like the traveling back in time to shoot your father before you were conceived concept... Which, if your Dad didn't understand...

Nevermind.

Essentially, my take is that if you're going to go back in time, your pre-now adventures have already occurred, and it doesn't matter how much information you know about them beforehand, as one way or another, you're destined to repeat them.

R. A. Heinlein's, "By His Bootstraps" is a wonderful novella where a man caught in a several foreys through time attempted to do just that, once he caught on that he kept runing into himself. I won't reveal any additional details, except to say that I think you would find it a very enjoyable, and enlightening read.

astromark
2008-Sep-21, 07:25 PM
I might see things from a different view. The fact that what you ask can never be.
Things the mind can imagine do not mean they will or can happen. That is where this fits.
There can not ever be instant communication,
The worm hole is a mound of earth we call a casting... ask a worm.
Time travel has been a favorite subject of fiction writers, Its still fiction.
You can not have all you want.
When the physics says no, That is what it means. No.
The human mind can concept all the what ifs you like. It does not make it possible.

Drunk Vegan
2008-Sep-21, 07:26 PM
Your future yous will likely know how, where, and when you will die.
I wonder if they will tell you.

Who says you have to die at all if you have a time machine?

As long as paradoxes are both possible and have no ill consequences, there's no reason why you can't be effectively immortal by just snatching a new copy of yourself from the past any time you yourself are getting old. Or when one of yous (?) has died.

Add in some kind of memory transfer device and any young version of yourself you snatch from the past can be used to make you immortal.

So basically... eternal youth and immortality are side effects or time travel if paradoxes are not an issue.

EvilEye
2008-Sep-21, 09:54 PM
They don't affect the traveler, only the people left behind.... if multiple universes work.

kleindoofy
2008-Sep-21, 10:08 PM
Who says you have to die at all if you have a time machine? ...
Time machines and immortality have one thing in common: neither will ever exist. ;)

EvilEye
2008-Sep-22, 12:29 AM
Time machines and immortality have one thing in common: neither will ever exist. ;)

You are the time machine. Move and you have traveled through time.

Jeff Root
2008-Sep-22, 02:12 AM
Drunk Vegan,

Only one impossible thing at a time is permitted. Time travel does not
give immortality.

EvilEye,

Don't move, and you travel in time, too.

-- Jeff, in Minneapolis

EvilEye
2008-Sep-22, 11:55 AM
Drunk Vegan,

Only one impossible thing at a time is permitted. Time travel does not
give immortality.

EvilEye,

Don't move, and you travel in time, too.

-- Jeff, in Minneapolis

True. But technically, you can't not be in motion. You are the reference point in your time, so moving yourself is moving the reference frame.

Ken G
2008-Sep-22, 03:05 PM
You are the reference point in your time, so moving yourself is moving the reference frame.Wittgenstein pointed out something pretty amazing in that regard-- he said that he could not understand why people for millennia used the fact that the Sun appeared to orbit the Earth as evidence that the Sun really did orbit the Earth. He said that to use an observation as evidence of something, don't you have to be able to imagine an alternative possibility for that observation?

EvilEye
2008-Sep-22, 03:15 PM
Wittgenstein pointed out something pretty amazing in that regard-- he said that he could not understand why people for millennia used the fact that the Sun appeared to orbit the Earth as evidence that the Sun really did orbit the Earth. He said that to use an observation as evidence of something, don't you have to be able to imagine an alternative possibility for that observation?

Sure, but when speaking of the passage of time, it's all relative to the observer.

It's individualistic.

The person driving in a car is literally aging more slowly than the guy walking down the sidewalk. ...relative to each other.

Jeff Root
2008-Sep-22, 03:39 PM
Wittgenstein pointed out something pretty amazing in that regard-- he
said that he could not understand why people for millennia used the fact
that the Sun appeared to orbit the Earth as evidence that the Sun really
did orbit the Earth. He said that to use an observation as evidence of
something, don't you have to be able to imagine an alternative possibility
for that observation?
No.

But even if so, so what?

If I see the person step off the sidewalk and into the the side of the
moving car, that is evidence the person stepped off the sidewalk and
into the side of the moving car. I haven't imagined any alternative
possibilities. Maybe I'm able to imagine an alternative possibility, but
whether I am or not, my ability to imagine an alternative possibility
doesn't affect the fact that what I saw is evidence that what I saw
actually happened.

So I agree: Wittgenstein's comment is pretty amazing.

-- Jeff, in Minneapolis

Extravoice
2008-Sep-22, 03:52 PM
Assume you are in the future. Wormholes and time travel are obtainable, though only available to the top scientists.

Assume you are in the future. Wormholes and time travel are obtainable, though only available to the top scientists rich and/or powerful.

Fixed it for you. ;)

mugaliens
2008-Sep-22, 04:27 PM
The human mind can concept all the what ifs you like. It does not make it possible.

You said it, astromark! And if God meant man to fly, he'd have given him wings!

Yeah...

***

Old-timer: "You wanna do WHAT?"

50's geek: "Put a man on the Moon."

Old-timer (laughing): "That's what I thought you said, boy. Whoo-eee - you been smoking something funny? 'A man on the Moon' he says... Ha-ha-ha-ha.. That's a good one, son, a good one!

***
Old-timer (laughing): "A wireless telegraph? (gufaw) Are you out of your mind? What in the world are you using to carry the signal?"

Marconi: "It travels over the ether."

Old-timer (confused): "The 'ether?' You mean like whisky?"

***
Heinlein said it best: "Always listen to the experts. They'll tell you what you can't do, and why. Then, go do it."

Star Trek imagined that hand-held communicators wouldn't be available for a hundred years or so. A decade later, cell phones were all the rage, and two decades more we had satellite phones. Now we have portable, integrated computing/communication devices like Blackberrys that have far more horsepower under the hood than our old IBM PCs.

Ken G
2008-Sep-22, 04:34 PM
No.
Actually, I think the answer is "definitely yes".


But even if so, so what?That's for you to decide. I merely repeat Wittgenstein's insight.

EvilEye
2008-Sep-22, 07:29 PM
My son will be back this weekend, and learn that when you ask a question, you get a couple of good answers and a ton of bickering. heh....

edit - Oh yeah... he did get to read the first few, and totally accepted the fact that his question started out wrong.

Extravoice
2008-Sep-22, 07:54 PM
My son will be back this weekend, and learn that when you ask a question, you get a couple of good answers and a ton of bickering. heh....

That reminds me of the old joke about how many newsgroup subscribers it takes to change a lightbulb (http://www.blakjak.demon.co.uk/lite_b.htm).

Fiery Phoenix
2008-Sep-23, 04:23 PM
I might see things from a different view. The fact that what you ask can never be.
Things the mind can imagine do not mean they will or can happen. That is where this fits.
There can not ever be instant communication,
The worm hole is a mound of earth we call a casting... ask a worm.
Time travel has been a favorite subject of fiction writers, Its still fiction.
You can not have all you want.
When the physics says no, That is what it means. No.
The human mind can concept all the what ifs you like. It does not make it possible.

You do realize that there is no law of physics that prevents Time Travel, though, don't you?

astromark
2008-Sep-23, 07:33 PM
You do realize that there is no law of physics that prevents Time Travel, though, don't you?

No. I do not.

If some event has already happened and has become the history that past events are. Nothing can change that. It really is that simple. What has already accrued has already accrued. It can never be undone. To think any other reality is a fiction unsupported by fact. Fiction is not fact.

Making snide remarks about what you think might one day be does not change the fact. As we have not found evidence of time travelers vistaing us from the future we can not argue what we do not know. As wrong as the science fiction lovers think I am. They can offer no proof of the proposal. Time travel.

However I can now argue that we do travel through time. Unfortunately I am unable to control that passage. I was born, am living, and will die. That is regrettable but true.

Drunk Vegan
2008-Sep-24, 02:39 AM
If some event has already happened and has become the history that past events are. Nothing can change that. It really is that simple. What has already accrued has already accrued. It can never be undone. To think any other reality is a fiction unsupported by fact. Fiction is not fact.

What about those who purport that the quantum indeterminancy shows that every possibility that can happen, does happen?

Then when you travel backward in time, and for instance kill your grandfather, you are not creating a paradox. You have just moved into a parallel universe in which you killed your grandfather and were never born.

You yourself are not going to wink away - you were still born in the universe you came from. You just happen to be in a different universe now.


As we have not found evidence of time travelers vistaing us from the future we can not argue what we do not know.

Scientific precept:

Absence of evidence does not equal evidence of absence.

That they have not revealed themselves does not mean they are not here.

Or, if they aren't here yet it could be an indication that time travel will not be invented for some time, but when it is it will be restricted to traveling in any time period after the time machine was built.

Also it's worth noting that time travel could seriously pollute things if there is only one single timeline. The history would become fluid with enough people influencing things.

I would submit that the *only* stable configuration for a universe is for time travel not to be invented.

So after a while of people mucking around in the past, somebody changes something that causes the time travel machine not to be built.

Twenty years later or whatever, someone else discovers how to build a time machine. Same process.. until that machine is not built either.

The end result is that the history ends up being one in which a time machine is never built by anyone. Not because it can't be built, but because it's the only stable configuration for the universe. Enough people time traveling guarantees a timeline in which time travel is not discovered as a result.


As wrong as the science fiction lovers think I am. They can offer no proof of the proposal.

Nor can you offer mathematical proof that time travel is impossible.

Sam5
2008-Sep-24, 03:57 AM
Nor can you offer mathematical proof that time travel is impossible.

I think it's a conceptual issue. All we know in our world is the "cause and effect" progression of time and events. We don't observe any "effect and then cause". I've never seen any fallen trees suddenly rise up and create a backwards-turning hurricane.

Your comments about "parallel" universes reminds me of the people who talk about the "energy" of this and that (such as the energy of crystals) as if adding the word "energy" to their tall tale makes their tall tale believable and valid. All we know is one universe. Show me a parallel universe and I'll be more willing to accept it.

astromark
2008-Sep-24, 07:02 AM
What about those who purport that the quantum indeterminancy shows that every possibility that can happen, does happen?

-------- No, Thats nonsense.

Then when you travel backward in time, and for instance kill your grandfather, you are not creating a paradox. You have just moved into a parallel universe in which you killed your grandfather and were never born.

-------- No, That can not happen. Breaks my rules.

You yourself are not going to wink away - you were still born in the universe you came from. You just happen to be in a different universe now.

-------- No, The conservation of matter would prohibit such nonsense.



Scientific precept:

Absence of evidence does not equal evidence of absence.

That they have not revealed themselves does not mean they are not here.

-------- No, Yes it does. We do not do invisible around here.

Or, if they aren't here yet it could be an indication that time travel will not be invented for some time, but when it is it will be restricted to traveling in any time period after the time machine was built.

-------- Yes, yes. I have herd this before, its still rubbish. NO !

Also it's worth noting that time travel could seriously pollute things if there is only one single timeline. The history would become fluid with enough people influencing things.

I would submit that the *only* stable configuration for a universe is for time travel not to be invented.

--------- Absolutely. The first right thing you have said.:)

So after a while of people mucking around in the past, somebody changes something that causes the time travel machine not to be built.

Twenty years later or whatever, someone else discovers how to build a time machine. Same process.. until that machine is not built either.

The end result is that the history ends up being one in which a time machine is never built by anyone. Not because it can't be built, but because it's the only stable configuration for the universe. Enough people time traveling guarantees a timeline in which time travel is not discovered as a result.

------- Umm, Err, When I fathom what it is you actually said here i will comment. I think you have just shot your foot.



Nor can you offer mathematical proof that time travel is impossible.

------- and norr do I need to. The fact is it is not. Can not. Will never. It just can't be ever possible to change what has already happened.

Jeff Root
2008-Sep-24, 08:08 AM
What about those who purport that the quantum indeterminancy
shows that every possibility that can happen, does happen?

Then when you travel backward in time, and for instance kill your
grandfather, you are not creating a paradox. You have just moved
into a parallel universe in which you killed your grandfather and were
never born.
That isn't travelling backward in time, then, it is travelling into a
parallel universe. And it isn't killing your grandfather, it is killing
someone who was parallel to your grandfather. This way of dealing
with the paradox gives up on time travel and replaces it with travel
between parallel universes. It replaces travel to a place that we
know really existed with travel to a place that was invented for
the purpose of avoiding paradoxes.

-- Jeff, in Minneapolis

Drunk Vegan
2008-Sep-24, 02:53 PM
That is true Jeff. But from your perspective it might as well be time travel.

If no one bothered telling you that you were actually going to a parallel universe, it would still seem to you that you are time traveling and changing the world by doing so.

Doesn't mean you'd be right, but that is what it would feel like.



The end result is that the history ends up being one in which a time machine is never built by anyone. Not because it can't be built, but because it's the only stable configuration for the universe. Enough people time traveling guarantees a timeline in which time travel is not discovered as a result.


------- Umm, Err, When I fathom what it is you actually said here i will comment. I think you have just shot your foot.

Not really. My assertion is that:

a) Time travel may be possible
b) Time travel may result in pollution of the past to such an extent that the universe becomes fluid. The only way for this fluidity to end and the universe to become stable again is for a timeline to be created in which time travel is not invented.

The universe then becomes a single continuous timeline again in which all events are safe because no one ever invents a time machine.

John Mendenhall
2008-Sep-24, 05:02 PM
Star Trek imagined that hand-held communicators wouldn't be available for a hundred years or so. A decade later, cell phones were all the rage, and two decades more we had satellite phones. Now we have portable, integrated computing/communication devices like Blackberrys that have far more horsepower under the hood than our old IBM PCs.



Mugsy, you're giving me a headache, you're making sense.

Seriously, 40 years ago I knew half a dozen reasons while cell phones couldn't work. 20 years ago we all gathered to look at a gigabyte hard drive that didn't take up a room. Today I carry a mobile computer, with a 10 gig chip, linked to the Net.

There are lots of reasons for qualifying all our declarations with "To the best of my knowledge . . ."

Regards, John M.

EvilEye
2008-Sep-24, 07:02 PM
Time is a distance problem. Cause and Effect are how we measure it. And you can only measure it from where you are at any given point. Therefore... any measurement will be forward. Even travel back in time (if possible) would be seen forward by the observer. Your clock won't tick backward.

Sam5
2008-Sep-24, 07:18 PM
Time is a distance problem. Cause and Effect are how we measure it. And you can only measure it from where you are at any given point. Therefore... any measurement will be forward. Even travel back in time (if possible) would be seen forward by the observer. Your clock won't tick backward.

Sure. We can all move backwards in space, but not in time. If we invent a really fast rocket, we can travel to a place in space where the earth used to be. But we can't move all space objects to where they all used to be in the past. We can all visit the little town we grew up in years ago, but we do it by always going forward in time, and that little town always changes.

astromark
2008-Sep-24, 07:21 PM
Mark was right, It would appear.
That is what the history books will say.
As EvilEye so eloquently put. "Your clock won't tick backward."
If an event has happened, it is history. Nothing can actually be changed that has actually happened.

Drunk Vegan; You tell me how you think that could be wrong please?
and not every thing we imagine has become a fact. Do you want the list?

Pippin
2008-Sep-24, 07:32 PM
There is only one accepted theory of possible time travel I am aware of that does not void physical laws as it the travel of observation and not presence in the past. It is the same in reverse as what our astronomers do today, but requires technology that is currently and possibly never able to exist.
Take a giant telescope, travel away from earth(or wherever) at faster than the speed of light. You would then be able to view history as it happened, but be unable in anyway to affect that history.

Drunk Vegan
2008-Sep-24, 09:18 PM
That is not time * travel * , that is time *viewing*.

And the only way to be able to view the past is if you are capable of traveling faster than light, something that is supposedly impossible.

For instance, if you were able to instantaneously jump 100 lightyears away from Earth, then you would be viewing the Earth in 1908 when you pointed a telescope at it.

Slower than light speeds wouldn't help - you'd always be viewing the Earth in "real time" when you looked back. Only by traveling faster than light do you gain "past perspective" as I'm describing.

If your trip wasn't instantaneous it'd be different too - like, for instance, if your ship did 2X the speed of light - going 100 lightyears out you would be viewing Earth as it was 50 years ago.

Fiery Phoenix
2008-Sep-24, 09:44 PM
That is not time * travel * , that is time *viewing*.

And the only way to be able to view the past is if you are capable of traveling faster than light, something that is supposedly impossible.

For instance, if you were able to instantaneously jump 100 lightyears away from Earth, then you would be viewing the Earth in 1908 when you pointed a telescope at it.

Slower than light speeds wouldn't help - you'd always be viewing the Earth in "real time" when you looked back. Only by traveling faster than light do you gain "past perspective" as I'm describing.

If your trip wasn't instantaneous it'd be different too - like, for instance, if your ship did 2X the speed of light - going 100 lightyears out you would be viewing Earth as it was 50 years ago.

Are you sure of that? I thought traveling at FTL speeds would allow you to travel ONLY to the future. Actually, it seems to be a correct theory one way or another. Meaning, if you were to instantaneously jump a hundred light years away from Earth (as in your example), you would see the planet as it was a hundred years ago. So, to you, Earth is in the past. And to Earth itself, you're in the future - if that's clear enough for you to know what I mean.

mugaliens
2008-Sep-24, 09:59 PM
Mugsy, you're giving me a headache, you're making sense.

And you're all the way over there! Over here, my sense-making resulted in the world growing dark, but this inner light began blazing like fire from my eyes and a sinister-looking evil grin!

No, wait, that's just my pumpkin. My bad.

But good "to the best of my knowledge" caveat, John. That's all we can ever say.

Drunk Vegan
2008-Sep-24, 10:26 PM
Are you sure of that? I thought traveling at FTL speeds would allow you to travel ONLY to the future. Actually, it seems to be a correct theory one way or another. Meaning, if you were to instantaneously jump a hundred light years away from Earth (as in your example), you would see the planet as it was a hundred years ago. So, to you, Earth is in the past. And to Earth itself, you're in the future - if that's clear enough for you to know what I mean.

Again, I'm not saying anything about time travel there.

IMO FTL travel would not, in fact, allow travel to the past. You'd just get where you're going faster.

Wormholes on the other hand are another story. Those could in fact be utilized to create time travel, assuming you could create two traversable ends of a wormhole and then fly them away from one another at relativistic, slower-than-light speeds.

But yes, I'm certain that the only way to view Earth's past is by using FTL speeds. And no, you wouldn't be "in the future" any more than I would consider myself to be in Alpha Centauri's future just because when I point a telescope at it I'm viewing it as it was 4.3 years ago. If I were to jump back to Earth at FTL speed it would still be the same day I left, assuming the trip were instantaneous both ways.

It took 4.3 years for that light to reach my telescope, so presently at Alpha Centauri it is 2008 just as it is 2008 here. I'm just seeing the light from early 2004.

Isn't relativity fun? :)

Fiery Phoenix
2008-Sep-24, 10:34 PM
Again, I'm not saying anything about time travel there.

IMO FTL travel would not, in fact, allow travel to the past. You'd just get where you're going faster.

Wormholes on the other hand are another story. Those could in fact be utilized to create time travel, assuming you could create two traversable ends of a wormhole and then fly them away from one another at relativistic, slower-than-light speeds.

But yes, I'm certain that the only way to view Earth's past is by using FTL speeds. And no, you wouldn't be "in the future" any more than I would consider myself to be in Alpha Centauri's future just because when I point a telescope at it I'm viewing it as it was 4.3 years ago. If I were to jump back to Earth at FTL speed it would still be the same day I left, assuming the trip were instantaneous both ways.

It took 4.3 years for that light to reach my telescope, so presently at Alpha Centauri it is 2008 just as it is 2008 here. I'm just seeing the light from early 2004.

Isn't relativity fun? :)

Indeed it is! And, valid point.

Pippin
2008-Sep-25, 01:39 AM
That is not time * travel * , that is time *viewing*.

And the only way to be able to view the past is if you are capable of traveling faster than light, something that is supposedly impossible.

For instance, if you were able to instantaneously jump 100 lightyears away from Earth, then you would be viewing the Earth in 1908 when you pointed a telescope at it.

Slower than light speeds wouldn't help - you'd always be viewing the Earth in "real time" when you looked back. Only by traveling faster than light do you gain "past perspective" as I'm describing.

If your trip wasn't instantaneous it'd be different too - like, for instance, if your ship did 2X the speed of light - going 100 lightyears out you would be viewing Earth as it was 50 years ago.

No fair! disagree with me, paraphrase everything thing I said and take credit for being a genius. I need an occasional respectable post to make up for all my foolish ones!

EvilEye
2008-Sep-27, 12:30 PM
*edit* <for dumb thought.

If I jumped 100 light years away instantly, I would not be travelling back in time at all...or forward in time. I would be teleporting. I would be that far away, and have to wait 100 years for the light from where I left to catch up with me.

Drunk Vegan
2008-Sep-27, 01:09 PM
*edit* <for dumb thought.

If I jumped 100 light years away instantly, I would not be travelling back in time at all...or forward in time. I would be teleporting. I would be that far away, and have to wait 100 years for the light from where I left to catch up with me.

Yep.