Time Trip - questions and answers (How widely accepted is the theory that we can travel in time?)

BBC ^ | Friday, December 26, 2003 | BBC

[Ichneumon]

Science fiction writer Larry Niven pointed out an interesting concept: Time travel is "unstable".

For example, if someone invents a working method of time travel on January 1, 2004, then there will be lots and lots of time travelers going back to visit past years prior to 2004.

With all the changes they'd inevitably make to the past, sooner or later someone is going to end up making a change that will alter January 1, 2004 enough that time travel *doesn't* get invented. For example, they might accidentally interfere with the birth, life or ancestry of the inventor, or start events in motion that sent him into a career in painting rather than physics, or they might interfere with earlier inventions which the time machine used as parts, or... Any number of things.

So eventually the past will happen to be altered in a way that "uninvents" the time machine that would have been built on 1/1/04, and *poof*, no time travel after all.

Then in the new timeline, someone else will eventually invent the time machine on some other date -- until *it* gets "uninvented" by people twiddling with the past.

Rinse, repeat.

So Niven's conclusion is that even if time travel into the past is possible, it'll keep preventing itself from being invented (for long, anyway).

On a similar note, I saw a trailer for an upcoming film ("The Butterfly Effect") which seems to be based on a somewhat related idea. A guy figures out how to travel into the past by sheer concentration, and he tries to prevent his dead girlfriend's death in the past. But every time he goes back and makes a change, the "ripples" of unintended consequences keep making the big picture even worse... It looks like a good film.

[Reaganwuzthebest]

I currently have a 2 hr commute and it just sounds so tempting to walk out the front door and in the blink of an eye to have arrived at my destination.

I'd be happy if they would just fast-forward to the Jetsons. Wouldn't it be great to fly to work everyday in your own personal car plane?

[greydog]

Makes me think of the movie Slaughterhouse-Five. Anybody heard where Paul Lezaro is?

[gdc61]

The 5th dimension. The realm where time does not exist. the entire universe from creation to judgment in a twinkling of the eye.

[baltodog]

This article seemed very good until:
"This is well illustrated in the film Bill & Ted’s Excellent Adventure."

[flashbunny]

Traveling back in time could probably be ruled impossible because you are not only traveling back in time, you are traveling back in space. If you are in cleveland right now, and want to visit cleveland 100 years ago today, you have to take the following differences in position into account:

Rotation of the earth.
Earth revolving around the sun.
Our solar system moving around in the milky way galaxy.
The milky way galaxy continually moving away from the center of the universe.

So basically, if you are in cleveland right now and zap yourself back 100 years, you'll have to wait 100 years for the earth to catch up with you, because it's a loooooooooooooooong way away.

Ad to this conservation of matter and conservation of energy, and you cannot travel in time without breaking those two laws. Basically, if I do manage to drop back into the same spot cleveland was in 100 years ago, I have instantly added a whole bunch of matter to the universe as it existed then. And taken a whole lot of matter out of our present day universe. Now, the present day might be easy by converting myself to energy, but finding a way to convert energy out of thin air into matter 100 years ago is going to be a doozy of a problem.

[flashbunny]

Actually, bill and ted's excellent adventure does show some good representation of time travel actions and consequences, but absolutely nothing like he commented on.

[BenLurkin]

" . . . instantaneously turning yourself into a tomato. . ."

Haven't tried that yet.

Once tried to boil an egg using only the power of thought.

After focusing for several hours I did manage to get the egg up to room temperature.

[IrishCatholic]

I can almost see the outside of Plato's cave on this one. I was going to post something in an attempt to be funny but post 13 killed that. It speaks to time, loss, regret, love, life, and hope.
I approach time different. Time is our concept of being. It doesn't really exist. There once was no space, therefore there was no time. The universe is expanding, therefore it isn't infinite. There is something outside of space. So there is something outside of time. The whole existence of matter, dark matter, super strings, mass distribution of the universe (visible so far) speaks to an analogy of the smoke left after a fourth of july firework. It was bright and shiney, now it is just a memory.
I think that we are on one little planet, not yet convinced that we should venture out into the neighborhood, much less the great beyond. Time travel? I would just guess that someday post 13 will get the chance to talk with her dad, get a hug, and catch up.
Time? not too worried about it. The human mind and soul really aren't connected with time. Time is just something we use to tell when dinner is ready.

[I_dmc]

I never understood the 'grandmother paradox'. I see no reason that one couldn't go back and affect history to the degree of eliminating your own existence. The real question would be, would you actually cease to exist? I tend to think no. I believe one would make oneself an 'anomoly'. The key is the past that created you would not be altered, only the past when you came back.

[I_dmc]

From what I recall of "The Philadelphia Experiment", it invovled time travel, which wasn't a desired result. It also involved spatial displacement, which may have been coincident with time travel.

[Lucy Lake]

As early as tomorrow, Coast to Coast show host George Noory plans a time travel experiment under the supervision of physicist and hypnotherapist, Dr. Irving Glotch.

"George has submitted two time periods he is interested in traveling back to: Roswell, NM July 1947 and to the mid-6th century to see if an asteroid hit caused the Dark Ages."

[I_dmc]

This is a disturbing thing to experience. I've been in other places in dreams, only to discover that what happened there, in my dream, did, in fact, happen there.

[Reaganwuzthebest]

I see no reason that one couldn't go back and affect history to the degree of eliminating your own existence.

The original Star Trek did an excellent episode on that possibility, which is anyone who traveled back in time could not alter any events without running the risk of affecting their own existence.

It might explain why if there is in fact those from the far future who managed to go back have done nothing to prevent a Hitler or a Stalin.

[ffusco]

I was thinking about Plato's Cave as well. It is possible to see the past but not interact with it.

[ffusco]

The Squire of Gothos episode. Man I am a NERD!

[I_dmc]

Mankind's greatest weakness is the necessity to define things in order to understand them. There is no space, there is no time, no dark matter, etc, etc. All those things are man's attempts to define what he cannot understand, in a way so that he may understand. "Seeing isn't believing, believing is seeing".

[Captain Beyond]

bump

[Orangedog]

If it's possible to build a machine to travel back in time, then where are the time-travelers from the future? Maybe they're investing in the stock market.

If it's possible, they could be here. Or it's possible that in the grand scheme of things, this part of history is not significant enough to warrant any attention by historians. Now I could buy that last part. I've spent 20 years trying to pretend the 1970's never happened. ;)

[I_dmc]

Quick. Does anyone actually remember the 1970's? Maybe they didn't happen.