Seriously thoughtful Is Time Travel possible

[pilotbob]

I spun this thread off the sf to fact thread because I wanted to continue the discussion.

The most recent episode of Lost did a really awesome sub-thread on this. (Since Lost's plot includes time travel). Hugo and Miles were discussing the ramifications of them killing someone in the past that they knew to exist in the future.

I subscribe to Miles view basically (assuming for a minute that time travel is even possible) that the past happened. You can't change the future. What ever you do in the past already happened. So, history knows you are coming, and you already did what you did.

Hence the episode name of "What happened, happened." I thought it was one of the best episodes. And no, please don't make this thread about Lost.

BOb

[Timoleon]

Here's an article that has surfaced on the web in the last few days that seems to throw cold water on the possibility of time travel --- to the chagrin of all us science fiction buffs :

http://www.technologyreview.com/blog/arxiv/23292/

Basically (very basically! ) some new theoretical advances/postulations in quantum theory cast doubt on the possibility of building something called an "Alcubierre Drive", which would, in effect, allow one to move at a perceived speed greater than the speed of light even though Einstein's limits are not breached.

It does this by moving space-time itself, as opposed to moving through space-time, by employing various quantum effects (wrap your head around that one!). You take your bubble of space-time with you. The sort of thing that a typical schlump in a Type II or Type III civilization might do for a Sunday drive through the galaxy.

My own quandary with this is this: What happens when you reach your destination and turn off your Alcubierre drive and your little bubble bursts? Are you in the future, present, or past? If you are in "the present", then time travel would not seem to have been affected; you've just arrived at your destination quicker, that's all. But, your space-time bubble by definition is different from the space-time "around" you, so how could time travel not be affected, either past or future?

Anyway, the question seems to be moot, since these theoreticians say that quantum theory dictates that the Alcubierre Drive can't be done, even by a time-lord sort of guy.

A word of warning: My own ramblings may not have anything to do with anything --- I'm a confirmed lotus eater. But it's fun to talk about!

[slayda]

Originally Posted by pilotbob

I spun this thread off the sf to fact thread because I wanted to continue the discussion.

The most recent episode of Lost did a really awesome sub-thread on this. (Since Lost's plot includes time travel). Hugo and Miles were discussing the ramifications of them killing someone in the past that they knew to exist in the future.

I subscribe to Miles view basically (assuming for a minute that time travel is even possible) that the past happened. You can't change the future. What ever you do in the past already happened. So, history knows you are coming, and you already did what you did.

Hence the episode name of "What happened, happened." I thought it was one of the best episodes. And no, please don't make this thread about Lost.

BOb

But what if, as some writers have suggested, when you return to the present, it is an alternate universe present to which you return? You did not affect your original present but instead spawned a new universe.

Pair of Docs!

[Greg Anos]

That's using John Wheeler's Multiverse concept for quantum uncertainty. Of course the question arises, where does all the energy come from to create each new alternate universe. One way out is what I call the pop-bead multiverse. At the big bang, and infinite number of universes were created, and time travel would simply be shifting from one alternate universe to another, exiting and re-entering the universes at different time points. <Shrug> Who knows?

[dreams]

I've often wondered about this..

If quantum matter behaves erratically and doesn't follow classical physical laws, then there are more laws operating in the universe than we know.

Our space is three-dimensional and time is considered fixed at one, and gravity affects amount of pull/bend then when traveling through this bend we are "time traveling."

If we find where the bend is, we can "time travel". So, isn't a wormhole the bend and additional connection of a greater pull between the bend?

I know that there is String-theory and M-theory but if we are talking larger than subatomic particles, ourselves, then this seems more feasible.

Whoa... Way more confusing to think about than I thought.....

Can I just say, "I believe!"?

[Sparrow]

What does 'time travel' mean?
I saw this thread several hours ago; now I'm back, there are more posts, and it's several hours later.

I appear to have travelled through time from the past to the present.

[pilotbob]

Originally Posted by Sparrow

What does 'time travel' mean?
I saw this thread several hours ago; now I'm back, there are more posts, and it's several hours later.

I appear to have travelled through time from the past to the present.

To me, "Time Travel" means moving through time at a rate other than 1 minute for every minute that elapses. Or the ability to move backward through time.

I think it is fairly understood what "Time Travel" means.

Right there is a good argument against travel to the future. It hasn't occurred yet. How go you go there?

BOb

[Sparrow]

Originally Posted by pilotbob

To me, "Time Travel" means moving through time at a rate other than 1 minute for every minute that elapses. Or the ability to move backward through time.

I think it is fairly understood what "Time Travel" means.

oops, skulks back to the Lounge

[pilotbob]

Originally Posted by Sparrow

oops, skulks back to the Lounge

Sorry I didn't mean to scare you away.

BOb

[HarryT]

Originally Posted by pilotbob

Right there is a good argument against travel to the future. It hasn't occurred yet. How go you go there?

BOb

There seem to be two schools of philosphical thought about just what "the future" is:

1. That the future is fixed and "pre-ordained" and that the whole of time is "there" - we just cannot perceive it yet.

2. The so-called "multiverse" theory which says that any time any decision is made, the universe "branches" and two entirely new universes go forward, one in which the decision went one way, and one in which it went the other.

[slayda]

Originally Posted by HarryT

There seem to be two schools of philosphical thought about just what "the future" is:

1. That the future is fixed and "pre-ordained" and that the whole of time is "there" - we just cannot perceive it yet.

2. The so-called "multiverse" theory which says that any time any decision is made, the universe "branches" and two entirely new universes go forward, one in which the decision went one way, and one in which it went the other.

But how do we know even if the universe is really there or just in our mind and springs into "being" only when we look to see if it is there? If that is the case the the whole concept of past & future are meaningless since there really isn't even a "present".

[pilotbob]

Originally Posted by HarryT

2. The so-called "multiverse" theory which says that any time any decision is made, the universe "branches" and two entirely new universes go forward, one in which the decision went one way, and one in which it went the other.

I can't fathom this being the case. Yes, I have heard this before. However, first, every decision is not boolean. Also, every person makes millions of decision every day... so there would be so many universes that you couldn't comprehend them.

King's _Ur_ is based on this concept or a multi-verse FTW.

BOb

[HarryT]

Well, what's interesting is that according to the General Theory of Relativity, the universe "consists" of 4-dimensional "spacetime" (3 dimensions of space, and 1 of time) and all four dimensions are essentially equivalent and interchangable. It's rather a mystery which, as far as I know, nobody has yet come up with a good explanation for) why it is that we can perceive and freely move through the three spacial dimensions, but can only perceive the "present" and move at a fixed rate through the temporal dimension.

Fun stuff to think about!

[HarryT]

Originally Posted by pilotbob

I can't fathom this being the case. Yes, I have heard this before. However, first, every decision is not boolean. Also, every person makes millions of decision every day... so there would be so many universes that you couldn't comprehend them.

Yep - that's right. Basically, every time a subatomic particle made a random "choice" about which energy state it should jump to - bang! - another universe split. The number of them would be mind-bogglingly inconceivable.

[montsnmags]

Originally Posted by pilotbob

...

I think it is fairly understood what "Time Travel" means.

It's probably worth pointing out, however, that you probably exclude the relativistic effects of travelling away from the earth at a sufficiently fast speed for a sufficient distance, and then returning the same way, and thus travelling "into the future".

Right there is a good argument against travel to the future. It hasn't occurred yet. How go you go there?

See above.

Originally Posted by pilotbob

I can't fathom this being the case. Yes, I have heard this before. However, first, every decision is not boolean. Also, every person makes millions of decision every day... so there would be so many universes that you couldn't comprehend them.
...
BOb

Is it worthwhile at this point to note that an inability to comprehend, fathom or conceive something does not preclude the possibility?

Cheers,
Marc