Understanding the Paradox of Backward Time Travel: Why We Can't Go Back

[wimms]

-- Physical entity and imaginary entity cannot interact. They are incompatible.

Why?! You cannot have an imaginary entity, without there first having been a physical interation in the brain.

Maybe its not clear what interaction is? Its what we observe as mutual exchange of energy, within all of the conservation laws.
When you try to imagine nuclear explosion in your head, I'm sure you can get the image. But when you get that image, I'm sure you hometown will not get blown away.. Your imagination does not have influence to not a single atom in your body, its a shadow. Its not even clear what we perceive as thought. But one thing is clear, our thought image can be larger than our brain, it exists in our mind for short time, and is recycled into other thought that engages same amount of neurons, but is magnitudes smaller in any conceptual respect (yet may have more influence on our body, like reverting from concept of infinities to a concept of tits).

-- Imaginary entities at different levels of abstraction cannot interact.
Why not? I also really don't get what "different levels of abstraction" means.

something forms what we know as quants. Quants form what we know as atoms, atoms form molecules, molecules form chemistry, materials, that form solid and other bodies, bodies form celestrial bodies, they form star systems, galaxies, etc. These examples of abstractions. But they have corresponding physical systems. To say that 1 hydrogen atom interacts with what you call car is nonsense. Or that your car interacts with galaxy. Atom can interact at atom level only, and car at mechanical level.

But why? Without the physical (brain) interacting with the conceptual (mind), science could not exist, because we would be unable to ponder anything.

Yes, but not the opposite. Our brain can perfectly exist without our marvellous conceptual mind. Concepts you imagine do not exchange energy with your neurons. Its only neurons that exchange energy.
Shadow of an object does not exchange energy with that object, they don't interact. Shadow is not physical entity, its something else, illusion perhaps. Our mind is able to create those shadows and observe them. That does not make shadows physical.

It can in my (conceptual) mind. Besides, water isn't a concept - it is a physical entity. Subatomic physical things interact a certain way, to produce more advanced physical entities.

Water is concept, that has corresponding physical entity. Triangle is concept, that does NOT have corresponding physical entity. Bermuda triangle does have physical entity. How would you make abstract idea to exchange energy with physical entity??

Another thing I wonder about: Why is it that you include theoretical particles, such as photons, in your list of "real physical things"?

Did I mention photons? I include all that can exchange energy within laws of conservation. I try to see them in anterior-posterior hierarchy, and judge what are compatible concepts for interaction. Trying to forcibly mate incompatible concepts can lead to weird results, and getting stuck with progress.

There is something wrong at quantum level with our theories. If not anything else, then they are way too complex for levels more fundamental than molecules. Maybe its result of mating incompatible concepts, and missing some intermediate abstractions.

BTW, we could discuss equations if you wanted to, but I don't see how it clears much up, except for the fact that 1D entities can be physical.

No, I don't want equations unless they seem important. But I'd like to understand how 1D lines can be physical. I can understand ropes, but 1D lines?

 

[The_Lance]

You people wrote a lot on this topic, it was difficult reading all of it. Though, it was the correct thing to do because a good portion of my view points have already been cleared up by wimms.

Except, wimms, you claim that physical entities can not interact with imaginary entities. If so, then I was wondering why it is that when some people on a perfecly warm day think of the artic, they shiver? Is this not an example of the thought of the artic weather interacting with their physical body?

If you can clarify this maybe I can fully see your perspective of the subject.

I must admit that this forum has made me think of time in new ways, but what I think of as time is something that mimics the properties of a dimension without actully being one. I think that we are being carried though time by means of something like inertia. Once we were set in motion and now we are holding to that tendency to keep going forward. And inertia can't be manipulated (yet ).

 

[Mentat]

Originally posted by wimms
Maybe its not clear what interaction is? Its what we observe as mutual exchange of energy, within all of the conservation laws.
When you try to imagine nuclear explosion in your head, I'm sure you can get the image. But when you get that image, I'm sure you hometown will not get blown away.. Your imagination does not have influence to not a single atom in your body, its a shadow. Its not even clear what we perceive as thought. But one thing is clear, our thought image can be larger than our brain, it exists in our mind for short time, and is recycled into other thought that engages same amount of neurons, but is magnitudes smaller in any conceptual respect (yet may have more influence on our body, like reverting from concept of infinities to a concept of tits).

Alrighty then. I'll disregard that last sentence.

You are still not seeing my point. A concept interacts with the physical brain, and vice versa. This is evident in the fact that a concept causes an energy/matter reaction to occur in the brain (and possibly other reactions, due to neural stimulus, such as the feeling of anxiety. Think about it.).

something forms what we know as quants. Quants form what we know as atoms, atoms form molecules, molecules form chemistry, materials, that form solid and other bodies, bodies form celestrial bodies, they form star systems, galaxies, etc. These examples of abstractions. But they have corresponding physical systems. To say that 1 hydrogen atom interacts with what you call car is nonsense. Or that your car interacts with galaxy. Atom can interact at atom level only, and car at mechanical level.

Why is it that you accept that atoms form these other "concepts" - such as a car - but won't accept that the atoms in the brain form concepts as well?

Yes, but not the opposite. Our brain can perfectly exist without our marvellous conceptual mind. Concepts you imagine do not exchange energy with your neurons. Its only neurons that exchange energy.
Shadow of an object does not exchange energy with that object, they don't interact. Shadow is not physical entity, its something else, illusion perhaps. Our mind is able to create those shadows and observe them. That does not make shadows physical.

Shadows are not physical entities. In fact, they are the absence of the physical entity, light. However, I don't see the relevance of this to your argument.

Water is concept, that has corresponding physical entity. Triangle is concept, that does NOT have corresponding physical entity. Bermuda triangle does have physical entity. How would you make abstract idea to exchange energy with physical entity??

I could make the physical entities in my head (called neurons) exchange energy, merely by thinking about such "concepts". How does that allow for these thoughts to be any less "real" then acual water?

Did I mention photons? I include all that can exchange energy within laws of conservation. I try to see them in anterior-posterior hierarchy, and judge what are compatible concepts for interaction. Trying to forcibly mate incompatible concepts can lead to weird results, and getting stuck with progress.

But photons are energy, and thus they are part of the exchange of energy as well. And yet, they are theoretical, and will remain such forever.

No, I don't want equations unless they seem important. But I'd like to understand how 1D lines can be physical. I can understand ropes, but 1D lines?

Yes, I don't see how that's any harder to believe in than 0d points.

 

[LaplaceOperator]

Let's get this discussion back to physics:

[*Slaps self on head* now I remember why I disagreed with Zefram, when he made (sort of) the same point as Hurkyl is making. It's all in the way we think of time. You see, you can think of time as being like the spatial dimensions, in the sense that if I put something in a certain place (in space), it will still be there when I look away. But this is not how I view time. As I see it, when you continue down the T dimension, everything that you "have done" (past tense) "disappears" (or ceases existing). I say this because, if it were "still happening", then it would be happening in the present, not the past. The past is compose of things that "have happened", it does not contain things that "will happen" or "are happening".

But according to relativity, the thing you call "the T dimension" depends on your frame of reference.

Take the following example from special relativity:

Consider the following two events-
EVENT A - My phone rings at my house, at 9:30 AM.
EVENT B - A meteorite hits Jupiter, at 9:40 AM.

According to an observer on earth, EVENT A occurred 10 minutes before EVENT B. But what about an observer traveling at 0.9c from Earth to Jupiter?

You can use the Lorentz Transformation to show that for such an observer, EVENT B would occur over 20 minutes before EVENT A! The order of events is reversed!

How is this possible? Because even in special relativity, two different observers measure time along a different "T dimension". Just like two people who are facing different directions would mean different things when they say "left" and "right".

Of-course, in the narrow framework of special relativity, you can't violate causality. The speed-of-light speed limit prevents you from doing so. But in GENERAL relativity, there are no such limits. By altering the metric of spacetime in just the correct way, you can - in theory - create a reference frame by which some effects preceed their causes. You can - in theory - create a reference frame by which 2005 (on earth) occurred before 1980 (on earth).

 

[michael_selway]

I explained the paradox of backward time travel, in the old PFs, and I would like to do so again.

Here is why it is impossible to travel backwards in time (and it doesn't matter how far backwards):

As soon as you travel to a time that is before the exact time when you started traveling, you create paradox. If I start traveling at 5:00 A.M. (I know that using minutes, as a way of measuring exact time, is crude, but it should get the point across), and I travel back to 4:59, I have yet to start traveling. But, if I have yet to start traveling, how did I get to 4:59? The answer: I didn't, it's impossible. Unless someone can prove me wrong, it makes no sense to imply that I can start traveling, after having already arrived at my destination.

Have u guy watched Bak to the future?

when u go back in time there is another u, a younger one

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http://www.putfile.com/media.php?n=StarWarsEpisode3Clip

btw here's a clip from the movie that i found!

great movie!

 

[Nomy-the wanderer]

To apply the special relativity, u need to be close to the speed of light...IF u r fast enough u can travel through some years of future, i'll state the same example again, i u r on a spaceship traveling thrpough space in a high speed close to the speed of light for a certain amount fo time, u'll be back on Earth after uhumm 5 years for ex. (that's according to u) while probably more than 30 years have passed on earth(i didn't calculate it, depends on the speed of course)

There's a 25 years difference between u and the other people who remained on earth, this means that if it was the eyar 2005 when u did so, then u've traveled to the year 2035 while mit was supposed to be the year 2010 for u..

But u can't go back, u've no way of slowing down, or gettin back in time, because the clock only ticks more seconds and there's no way to make it tick backwards..

 

[hershal]

I have not gone thru all the posts in the thread, except the first one and the last one. Accidently I came across a bit of information on BBC, just have a look about wht kind of backwards time travel can be possible.

http://news.bbc.co.uk/2/hi/science/nature/4097258.stm

 

[PRyckman]

only way to go back without paradoxes

No matter where you are in the universe due to relativity compared to energy you are always in the middle. That being said, If you could teleport halfway to the edge of the galaxy, since you'd still be in the middle the universe would only be half as old. The reason this does not create a paradox is because the amount of time you travel back is equal to the time it would take light to travel that distance. Therefor if you teleported one light year away from here you would be one year in the past. It doesn't create any paradoxes because there is no possible way to interact with your past self since you cannot travel faster than light.

Note that teleporting to Earth again from your new point in history would put you even farther back in time and you still couldn't get there any sooner because space would be more condense, and it's speed of expansion greater, it would balance the equation so that you could not get there any faster. I'd love to hear back from some of you on this, I think I found proof of it in E=mc2, a shortword on that
E=mc2 could also be an equation for pi, with c2 being radius

I've thought a lot about what we're missing in that equation, and I think that it is the Grand Unified theory that we all look for. And that there may only be 2 dimensions. Time and direction. Atleast at a sub atomic level. The only reason we perceive 3 dimensions is because of the uncertainty principle. As more and more forms of energy circle around each other there is increased certainty in they're position and decreased in their momentum, a balance of these two un/certainties allows us to see them as a point and not a direction.
Please feel free to email me, I might not remember to check this site and thread again. Patrick_ryckman@hotmail.com