luvluv

I know that the flow of time is relative, but is the present fixed? Would all observers, no matter their speed, agree that today was today?

It has been suggested to me that seeing the future would be impossible, because we aren't there to be seen. I assume by this that time travel is impossible, because if it was possible to "skip" over a segment of time, as opposed to traveling faster through time, nothing, no planets, stars, dimensions of space, would be there. If this is true, it would be possible to vary your motion through time but no potential for you to actually time travel. There would not even be space time for you to exist in in the future, since it would not have reached the "future" yet.

Do any theories of time have anything to say about whether it is possible to skip over some segment of time, or whether there is an absolute present? I know that in string theory it is possible to tear the fabric of space, could this be a means for time travel?

[ October 17, 2002: Message edited by: luvluv ]</p>

tronvillain

Is there an "absolute present"? No. If there is an absolute present, at what rate is it moving from the past to the future? Anyone who replies to that question with "The present is moving from the past to the future at a rate of one second per second." has not obviously not thought about the problem. That answer would only contain useful information if the "per second" referred to some sort of "meta-time", but as that only moves the problem back one step rather than solving it, it is far simpler to abandon notions of an absolute present.

Mageth

I think what he's asking is if two objects travelling at different relative speeds have a "present" that is "common" to both of them (that's not a good way to put it, I know), regardless that the two objects are travelling at different speeds and thus "experiencing" time differently.

For example, if a spaceship was travelling at the speed of light towards (or away from) the earth, and I was on the earth, a spacefarer on the spaceship would be "experiencing" time differently than I. However, at an instant in time for me (e.g. 19:14:00 on Oct 17, 2002) that I call the present, would ther be a corresponding instant in his time reference that the spacefarer would consider "the present"?

I may be all goobled up on this one, as relativity can be hard to think and talk about.

echidna

Now this is repetition. Apologies Luvluv, but we’re just engaging a complaint that this subject gets raised too often. The “does time exist ?” thread already postulates the same question as you do.

Does time exist ?
<a href="http://iidb.org/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=57&t=000603" target="_blank">http://iidb.org/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=57&t=000603</a>

(IMO repetition’s OK but preferably not in concurrent threads.)

Either way, the thread's relevant.

tronvillain

Well, he is obviously also asking whether the future exists "now" or will not exist "until" the present arrives there (quotations because English doesn't have really have the tenses for talking about this).

Mageth

You're right of course, tron. My response was based on knowledge of a previous thread from where I think luvluv got this question, not a critique of what you were saying. IIRC, he posed that God could know the future by travelling at the speed of light. I replied that that wouldn't get God into our future.

Oh, BTW, luvluv, I'm time traveling into the future right now, and so are you!

wdog

luvluv,

to clarify our position a little. we never really talked about time travel like what you are saying. the question at hand was whether an external observer, be it in this universe, the next universe, hypertime, or at the home depot checkout line could observe you simultaneous (in their frame of reference) at two or more times in your frame of reference. That amounts to really observing a multiple number of luvluvs since you would have to actually exist in those multiple frames to be observed, and those frames would have to exist as well.

that is different question than time travel.

atrahasis

This is the kind of thinking i was talking about <a href="http://iidb.org/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=57&t=000603" target="_blank">here</a>...

.....And i'm still waiting for an answer..

Ernest Sparks

luvluv,

"flow [of time]"
"[present] fixed"
"[time] travel"
"skip [over]"
"traveling [faster]"
"vary [your motion]"

All of the key words here (flow, fixed, travel, skip, traveling, vary) implicitly carry some sense of time measure within them. It is unavoidable. What can be done is to compare one system of time measure with another covering the same events and see if they are different.

---

"today was today?"

We can all agree that "I means me". Where we might disagree is whether "I means Ernest Sparks" or "I means Britney Spears", and so on. We can disagree whether "Now means October 18", unless we all agree to use some kind of universal date, like Greenwich Mean Time.

Ernie

luvluv

wdog:

I don't think so. I think if time were to take on the form of a plane, so to speak, then the axiom "An object can only exist at one space at one time" would be done away with. If the time line were a time plane, there wouldn't be any problem with me being in more than one place at "one time".

This gets into a side discussion of what C.S. Lewis said about the subject in the Screwtape Letters. He (through Screwtape) basically said that we get into trouble if we view "out of time" as a trick of God's perception. The proper way to think of it, he said, was that "out of time" was the way things actually ARE, and that the temporal view, percieving existence one momment at a time, is the illusion. In that scenario, we would have "temporal extent", we just wouldn't be aware of it.

I disagree. If I am not in the future, right now, for God to see, then I would not be in the future for any time traveler to see, either.

Also, if I am no longer in the past, then I would not be around to be seen by any time traveller visiting my past.

If we do not have any temporal extent, as you called it, then time travel is not possible. If the future does not exist "right now" then there is no future to travel into. But if there is a future to travel into, then it does exist "right now" and can therefore be observed.

[ October 18, 2002: Message edited by: luvluv ]</p>