[freudling]

Been doing some research on this topic for personal use. Interested in others commenting that have some background in physics, particularly quantum mechanics.

From what I understand, and correct me if I am in error in any respect, is such that, time slows at a certain rate of speed. The faster you go, the slower it goes, in relation to you, the person traveling at x speed. Those things around you that are stationary, or not traveling at a threshold speed, will see time pass as per 'normal'. So mere seconds to the traveler can equal hundreds of years to the non-travelers. I have read that there are several studies substantiating this hypothesis.

I guess the gaps in my knowledge are an ability to see space and time as a fabric, or whatever space and time are. I have read several explanations of space and time but all seemed a bit nebulous and incomplete. Which leads to another question about why time slows when you travel at a threshold speed.

Another point is all of the discussion revolving around what would happened if you traveled through time, that it were possible. Could you travel back? Are the time travel paradoxes just a result of antiquated thinking and theories?

[Railroader]

I've never traveled in time, but I do sometimes buy things from Radio shack.

Sorry. That's all I got.

[olePigeon]

Originally Posted by freudling 

From what I understand, and correct me if I am in error in any respect, is such that, time slows at a certain rate of speed. The faster you go, the slower it goes, in relation to you, the person traveling at x speed. Those things around you that are stationary, or not traveling at a threshold speed, will see time pass as per 'normal'. So mere seconds to the traveler can equal hundreds of years to the non-travelers. I have read that there are several studies substantiating this hypothesis.

That's called the Twin Paradox. You can get around this, funnily enough, by doing what Star Trek does: you create a warp bubble. Assuming time and space is an airport terminal, and everyone walking in the terminal is going at near the speed of light, you can go "faster" relative to everyone else by jumping onto the conveyer belt. The conveyer belt is representative of a micro-universe. Inside that universe you're going near the speed of light. Now if you create another micro-universe inside that one and go near the speed of light, relative to everyone else you're going 4x the speed of light. You create another universe and you're boing 16x the speed of light. So on and so on. Now all we have to do is create our own universes.

Originally Posted by freudling 

Another point is all of the discussion revolving around what would happened if you traveled through time, that it were possible. Could you travel back? Are the time travel paradoxes just a result of antiquated thinking and theories?

The universe (multiverse) isn't clumsy. There are a few paradoxes that will never happen because of the way time and space work. One is the classic, "If I travel back in time to kill my grandfather, I would never be born to make a time machine to travel back and kill my grandfather."

The way this is avoided is eerily simple: the moment you leave your current time & space, an infinite number of new timelines are created. If you go back in time to kill your grandfather, then only in that timeline will your grandfather be dead. It has absolutely zero baring on any other timeline.

This is precisely why you will never see anyone from the future, assuming time travel is/was possible.

Also, you can't go back in time and win the lottery. Random is random, it doesn't matter what point of time you're in. If you go back to last Friday with the winning numbers, the numbers will be different.

[reader50]

It sounds like you are looking for a discussion of time dilation. If you just want a simplified equation to play with in a spreadsheet, use this one:

time rate = SQRT (1 - v*v)

v = velocity compared to lightspeed - ie, 0.5 would be half lightspeed.
time rate will solve between 1 and 0, where '1' is the same rate you are seeing, and '0' would indicate time has stopped relative to you.

Time dilation belongs in the relativity camp rather than quantum mechanics, at least until someone comes up with a quantum gravity theory.

As to travelling backwards in time, the time axis is like the first 3 spacial axis, except that everything is required to travel at lightspeed on the time axis. On the spacial axis, only force carriers are required to travel at lightspeed, with the exception of the W and Z bosuns, which carry the nuclear weak force.

Relativity doesn't care which direction you travel on the time axis, so long as you remain at lightspeed at all times. Since you can't slow down, there is no obvious way to switch your direction. Time travel ideas involving rotating neutron stars or black holes all rely on twisting the space you travel through instead, and such solutions are currently beyond our engineering ability.

How time travel would work in a practical sense - ie, paradoxes - depends on physics we haven't worked out yet. So any such answers are speculative - pick some that look interesting, and script a movie. Others have made good money doing that.

[Doofy]

Time doesn't exist in the way we think it does - we only perceive it to do so.

All of eternity exists within a moment, and a moment is eternity.
Time is like this: • not this: ---------

Start from that assumption and you'll go further than you've ever gotten before.

[Rev-O]

Originally Posted by olePigeon 

The way this is avoided is eerily simple: the moment you leave your current time & space, an infinite number of new timelines are created. If you go back in time to kill your grandfather, then only in that timeline will your grandfather be dead. It has absolutely zero baring on any other timeline.

This is precisely why you will never see anyone from the future, assuming time travel is/was possible.

Also, you can't go back in time and win the lottery. Random is random, it doesn't matter what point of time you're in. If you go back to last Friday with the winning numbers, the numbers will be different.

The other way this is easily avoided is if one is more of a B-series believer in time as opposed to an A-series believer. Time travel is much less likely to completely impossible with B-series time. B-series time makes for really crappy science-fiction stories. These are my fairly off the cuff takes on two of the biggies of B-series time:

Eternalism (four dimensionalism) has all things existing simultaneously in the past, present and future and has time as a set dimension. Therefore all things have typical 3 dimensional descriptors and a fourth dimension aspect that ties them in a fixed aspect that expresses all the state combinations the matter has/can/will exist in. Can't really travel back in time if the past is a simultaneous aspect of the present. You can't really travel to the past because you can't leave the present because all things are set in place and located four dimensionally. Your past self still exists alongside your present self and your future self, and they are all one in the same thing, so once again, you can't travel back in time to see what your past self is doing because you are still your past self. Pretty deterministic view.

Presentism (which I believe in) kinda believes time doesn't exist at all: it is largely a function of our consciousness trying to come to terms with entropy. There is only the current state of matter. That state of matter is subject to entropy so the current state of matter is always in transition. Consciousness is an expression of electrical energy, standing wave fronts, whatever, that changes state and form continually. The discrepancy in states is noticed by consciousness which creates a god-of-the-gaps expression called time and based upon experience is able to posit and project expectations of future states of matter. So there is no past to travel to and no future to travel to. There is only the present which is a single expression of existence that is in flux. The me that started typing this response is not the me that is typing right now. The matter and energy that is me has changed entropically but has not moved forward through time. My perception of the entropic change is what we call time, but it is an illusion perpetuated by the infinitesimal entropic changes in my consciousness and physical form. It just makes sense to me ontologically.

[Rumor]

Ask Dakar. He was getting real good at it a while back.

[Thorzdad]

John Titor explained a lot about time travel.

[design219]

I have trouble with the "relative" part of time trave via speed. What if two light speed space ships shot away from each other in opposite directions, but actually traveled in a large circular path where they would meet half way around their circular path? They left each other at "relatively" twice the speed of light, but they should experience the same time.

[olePigeon]

Originally Posted by design219 

I have trouble with the "relative" part of time trave via speed. What if two light speed space ships shot away from each other in opposite directions, but actually traveled in a large circular path where they would meet half way around their circular path? They left each other at "relatively" twice the speed of light, but they should experience the same time.

The answer is: c

Most people think that if an object is moving at 10 Mph away from an object moving away at 10 Mph, they'd be moving 20 Mph relative to each other. That would be mostly correct. However, the problem is that measuring time + space at speeds approaching the speed of light becomes less accurate. Two objects moving away from each other at the speed of light will be moving away from each other at the speed of light. As long as at least one of the objects is moving at c, the answer will always be c (assuming it's a vacuum and there are no external forces.)

[freudling]

Good comments, keep em coming.

Presentism is very appealing.

[mattyb]

This stuff, and the above comments are way above me, but I read (and mostly didn't understand) about experiments that scientists proved that a neutron/proton/molecule/can't remember what travelled in time. May have been in the New Scientist. There is also the atomic clock in a fast aircraft stuff - which I didn't understand either.

But keep commenting, even dumb people like me enjoy reading what other people say about this.

[Doofy]

Originally Posted by freudling 

Presentism is very appealing.

It may be appealing - however, it's utterly wrong. Sometimes, fortune tellers and the like do get things right - which precludes the idea that there's only the present.

[design219]

Originally Posted by Doofy 

Sometimes, fortune tellers and the like do get things right - which precludes the idea that there's only the present.

Everyone who takes an educated guess sometimes get things right.

[Doofy]

Originally Posted by design219 

Everyone who takes an educated guess sometimes get things right.

I'm not talking the usual charlatans ("Is there someone called Dave here whose great, great, great grandmother is dead? I sense there is."). There's a very few people in this world who do actually get accurate premonitions. Even if there's only one, that discounts the presentism theory.

[osiris]

Time travel? Maybe not for thousands of years, or until we advance our civilization to a type 3 where we can go faster than the speed of light (or at least appear to) and can harness the power of a solar system. We are currently a type 0 (barely in control of our own lives).

Michio Kaku has a very readable book "Hyperspace" that explores a lot of this. It's fascinating stuff.
I'm not sure if paradoxes exist - once you create a new timeline, everything contained in it is also new, including your genetically and visually identical parents. If you kill your parent, only the new timeline parent would die.
Well, at least I guess this to be true. We don't know, no one does. My brain hurts.

[Chuckit]

Originally Posted by Doofy 

It may be appealing - however, it's utterly wrong. Sometimes, fortune tellers and the like do get things right - which precludes the idea that there's only the present.

I'm not sure about that. If tell you where a car coming down the road will be in 10 seconds, does that also disprove presentism?

[freudling]

I don't think being able to accurately predict future effects discounts presentism. If we say it does it would seem that presentism's proponents would say that our thinking is flawed. Yes, there is 'cause and effect' but they could still stand by saying time is not some linear entity like we think. Things just simply change and interact with one another. Time is simply a logical construction in our minds.

Also, Doofy, that is a very powerful comparison of two different concepts of time you have posted. I assume you would lean toward presentism as well, that time is sort of all around us and not linear. Does this not present problems for time travel then? "Time travel", the words, the concept, would thus be flawed because we think time is linear but if it does not exist, if things are just in flux, we can't really travel in time, we can only interact with particles and observe more effects.

[Doofy]

Originally Posted by Chuckit 

I'm not sure about that. If tell you where a car coming down the road will be in 10 seconds, does that also disprove presentism?

If it's come to you via a "vision" and it's a sufficiently detailed description to discount pure chance playing a part, then yes.

[Doofy]

Originally Posted by freudling 

Also, Doofy, that is a very powerful comparison of two different concepts of time you have posted. I assume you would lean toward presentism as well, that time is sort of all around us and not linear.

I lean towards presentism and eternalism simultaneously. There's no reason why they can't coexist.

Originally Posted by freudling 

Does this not present problems for time travel then? "Time travel", the words, the concept, would thus be flawed because we think time is linear but if it does not exist, if things are just in flux, we can't really travel in time, we can only interact with particles and observe more effects.

I wouldn't have said it presents problems for time travel. In essence, to "time travel" one would only have to train oneself sufficiently to allow for a sideways (to a different, currently existing past), rather than forwards (to the next "regular" second), progression through perceived time.

I don't know if that made sense. I've had a few Buds.

[FeLiZeCaT]

About Relativity, I suggest reading a geometrical demonstration of the Special Relativity variant:

"Very Special Relaticity; An Illustrated Guide", Sander Bais, 2007. Time dilation becomes visual through graphs. I enjoyed it.

You might find interesting Godel"s take on time from Pale Yourgrau's
"A World Without Time; The forgotten Legacy of Godel' and Einstein", 2005.

Time travel; is "travel" the right way to conceptualize it if consciousness plays such a significant role in causality?

[freudling]

I knew I would get good insight on MacNN, keep em coming...

[HenryMelton]

Hey, just for you guys, I slapped together a web page for this discussion. I'll leave it up for a couple of days, with my feelings about the real kind of time travel -- the science fiction kind.

[Chongo]

Originally Posted by Thorzdad 

John Titor explained a lot about time travel.

Art Bell claims he was given a time machine, but has been reluctant to use it.

[freudling]

Check this out:

http://www.youtube.com/watch?v=V7vpw4AH8QQ

So, time slows for Bertrand in the Ship, which is why things move fast relative to him, even though he is moving fast? Almost like the slow down of time causes him to be in a state of slow motion, even though he is in fact moving quickly. So relative to him, the beam of light passing him is almost like him standing still while it passes. Hard to understand, though, since even though he is traveling quickly, things relative to him moving at the speed of light, like the light, will be traveling at a rate 100% faster than the rate he is traveling: counterintuitive.

[Don Pickett]

Originally Posted by freudling 

From what I understand, and correct me if I am in error in any respect, is such that, time slows at a certain rate of speed. The faster you go, the slower it goes, in relation to you, the person traveling at x speed. Those things around you that are stationary, or not traveling at a threshold speed, will see time pass as per 'normal'. So mere seconds to the traveler can equal hundreds of years to the non-travelers. I have read that there are several studies substantiating this hypothesis.

It's not just several studies: it's a basic tenant of Relativity which has been proven over and over by experiment. GPS satellites don't work without correction for time dilation: because they are in high orbits, the GPS satellites are far enough from the Earth's mass to have their internal clocks run milliseconds faster than clocks on the ground. That a correction must be made is one of the more convincing proofs of time dilation.

Another thing: since the measurements from all freely floating reference frames are equally valid, all persons in any measured experiment will see their time running at one second equal to one second no matter their speed relative to c. While a short time may have passed for those traveling near c, and a long time may have passed for those traveling a slower speeds, both measurements are correct with respect to their reference frame.

Beyond these, time travel is currently impossible so far as we understand physics for two very basic reasons. One is that traveling backwards in time would mean returning to a time of lesser entropy than when the traveler began, which is a fundamental violation of the Second Law of Thermodynamics. The second is that traveling backwards in time by definition breaks causality, without which our entire understanding of physics falls apart. For us to travel in time, someone or some group will have to figure out how entropy and causality would be conserved.

[- - e r i k - -]

Originally Posted by Doofy 

There's a very few people in this world who do actually get accurate premonitions. Even if there's only one, that discounts the presentism theory.

Are you serious? Did you smack your head headbanging or something?

[Don Pickett]

Rereading your question, I see you have a basic misconception: no matter how fast you travel with respect to c, time will always move at one second = one second to you. In other words, if you take off and head to Proxima Centauri at .99 c, it will take you about 4.3 years to get there and 4.3 years to get back, as Proxima Centauri is about 4.3 light years away, and during the journey time will always move forward at one second = one second. In that interval time for those on Earth will have proceeded forward at one second equals one second, but you will be gone for several thousand years in their reckoning. But both of you would have traveled forward in time at exactly the "normal" rate.

If you could travel faster than c, you would automatically travel travel, as your time dilation becomes infinite with respect to someone observing you. In other words, you could theoretically travel across the entire universe in an instant. However, the fact that time dilation become infinite means that's the point at which our understanding of the physics breaks down, so we're not really sure what would happen at that point.

[Doofy]

Originally Posted by - - e r i k - - 

Are you serious?

Yup.

[B Gallagher]

Originally Posted by osiris 

Time travel? Maybe not for thousands of years, or until we advance our civilization to a type 3 where we can go faster than the speed of light (or at least appear to) and can harness the power of a solar system. We are currently a type 0 (barely in control of our own lives).

What are type 1 and type 2?

Originally Posted by Doofy 

All of eternity exists within a moment, and a moment is eternity.
Time is like this: • not this: ---------

Reminds me of Slaughterhouse-Five.

[Chuckit]

Originally Posted by Doofy 

If it's come to you via a "vision" and it's a sufficiently detailed description to discount pure chance playing a part, then yes.

So if I can visualize the car being 50 feet in front of where it is, that makes a difference?

What I'm saying is, we can already predict the future based on what we have in the present. The only way these predictions being particularly clear would make a difference is if we suggest a cause that involves the future existing together with the present.

[Chongo]

The Vulcan Ministry of Science has declared that time travel is impossible.

[andi*pandi]

Chronic Hysteresis, man. It's all about chronic hysteresis.

[ForestofIncandescence]

Originally Posted by Don Pickett 

Rereading your question, I see you have a basic misconception: no matter how fast you travel with respect to c, time will always move at one second = one second to you. In other words, if you take off and head to Proxima Centauri at .99 c, it will take you about 4.3 years to get there and 4.3 years to get back, as Proxima Centauri is about 4.3 light years away, and during the journey time will always move forward at one second = one second. In that interval time for those on Earth will have proceeded forward at one second equals one second, but you will be gone for several thousand years in their reckoning. But both of you would have traveled forward in time at exactly the "normal" rate.

If you could travel faster than c, you would automatically travel travel, as your time dilation becomes infinite with respect to someone observing you. In other words, you could theoretically travel across the entire universe in an instant. However, the fact that time dilation become infinite means that's the point at which our understanding of the physics breaks down, so we're not really sure what would happen at that point.

This book illustrates it:

"Very Special Relaticity; An Illustrated Guide", Sander Bais, 2007. Time dilation becomes visual through graphs. Becomes much simpler to understand.

[brassplayersrock²]

Just have a memory of something that you did, or had happen to you and then you've time traveled.

[ctt1wbw]

Originally Posted by Railroader 

I've never traveled in time, but I do sometimes buy things from Radio shack.

Sorry. That's all I got.

Did they ask for your zip code? Why the hell is that? I've not figured that out yet.

[ctt1wbw]

Originally Posted by andi*pandi 

Chronic Hysteresis, man. It's all about chronic hysteresis.

I need some chronic, man. Got some?

[Chuckit]

Just tell them 90210. That's what I always do when someone asks my ZIP code who isn't going to be shipping me something.

[Doofy]

Originally Posted by Chuckit 

Just tell them 90210. That's what I always do when someone asks my ZIP code who isn't going to be shipping me something.

Hi neighbour! <waves over fence>

[RhymesWithOrange]

Originally Posted by Shaddim 

Look everyone, ever wonder why we can't have discussions about certain subjects? There's your answer.

You're completely incapable of having a conversation without being rude, aren't you? I remember you saying that you're some type of atheist/agnostic sort of thing, right? Try being an adult first.

Please stay on topic!!11!

On topic...Time travel is impossible or we would have stumbled on some idiots from the future who totally ****ed up the 'prime directive'.

[Don Pickett]

Originally Posted by Shaddim 

I would, if I weren't so fed up with that type of crap.

Anyway, carry on. It's not like that type of whatever-he-is is even capable of empathy.

Time travel is impossible because it requires violating the second law of thermodynamics.

[ctt1wbw]

Plus, not everyone can afford one of those DeLoreans. Those are expensive.

[Shaddim]

Originally Posted by Don Pickett 

Time travel is impossible because it requires violating the second law of thermodynamics.

You're right, it is impossible. Altering one point of reference in an infinite spread of probabilities wouldn't change anything, from our perspective.

[turtle777]

Originally Posted by RhymesWithOrange 

Please stay on topic!!11!

Who the **c* are you ?

-t

[Chuckit]

I just deleted a flamewar. Please refrain from derailing the thread with personal attacks. Thanks.

[ctt1wbw]

Oh yeah? Well, your mother was a hamster! :


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