I have always been interested in the theory of time travel. What do you guys think about the theory? Do you think it is possible? I only bring this up because of the new movie coming out "THE TIME MACHINE"(and that I'm drunk right now) Its an interesting theory. CAPITALIST

I'm in favor of it.  Let me know when you have a trip planned, and I'll bring the beer.

Sounds like a plan tx_traveller

I dunno, everytime I think about time travel, the image of McFly kickin it to his mom pops into my head.  Imagine goin back and seeing some cutie only to find out its Aunt Esther?  Ugh!  The thought shrivels me weasle!

Well, in theory time travel [i]forward[/i] is possible, however time travel backwards is not.  AMHsix is on the right track here, part of it is the past no longer exists you can't go somewhere that does'nt exist.  There are a couple of more reasons, but I'll not get into them as the explanations are long, and Intro to Philosophy is way the hell back there in a place that no longer exists.[;)]

I'm all for going forward to see which companies I should buy stock in to be rich as hell.  The winner of every World Series and Super Bowl for the next 25 years.

   Cypher214...

   If guns kill people, I would like to know where mine has been hiding the bodies......


    [:D]  LMAO   Thanks buddy! It's gonna take me awhile to clean up all these Cheerio's I just spewed on my keyboard.

i'd deal witha all the assholes I hate before I gain the the motive [}:D].

ohh yeah and I'd find out who I marry, and where I am gonna live.

The past doesn't exist any more, and the future doesn't exist yet. Since neither of them exist at this time, yet time travel to the future is theoretically possible, this high-school-physics-failing person doesn't understand why time travel to the past won't work. It'd be nice to go back 2 generations and break up/prevent the marriages of Mr. & Mrs. Lautenberg, Feinstein, Schumer, etc.

Oh, and Stephen Baxter's book "The Light of Other Days" deals with time travel and wormholes, and in it travel to the past works but not the future.

O.K. I guess I should have elaborated smart ass, here goes.  Let's say someone invents a telephone that can call to the past, let's say we agree that I pick up the phone at 5:00pm and call you for a bit of info at 4:30pm, see where this is going yet you smart f$#^er?  Well, just in case you don't I'd never call cause I'd already have the info impossibilities.  As for the future not existing that depends upon which school of thought you belong to fate or free will.

The fact that we're all living in today and not yesterday strongly suggests that travelling forward in time is not only possible, it's inescapable. [;)]

Been a while since I've read "Hawking" but I believe parallel universe movement in time may be possible - based mostly on Hawking.

(Everyone should pay close attention to my opinion cause I passed physics ed.)

Time Travel That Doesn't Violate Physics

I came up with this idea years ago while on a 3-day tear.

1.  Learn to astrally project or travel in the dream world.  The astral plane and the dream world are both known to not be subject to our physical laws.

2.  Move up or down your personal time line as desired.  This part may require a bit of practice, but anecdotal evidence indicates it is possible.

3.  Possess yourself at the desired point on your time line.  If people can be possessed by demons and other spirits, there is no reason you can't be possessed by your own spirit.  

Example:  Your 50 year old self does as above and goes back and takes possession of the body of your 18 year old self.  You are now in the position of being 18 and knowing everything that is going to happen for the next 32 years.  At your personal level, the utility of the knowledge will not last.  If you avoid the first big mistake or two you made early in life, all the grief that followed from those mistakes won't happen.  So, you will be leading a new life with knowledge of your old one to draw on.  On a larger level, though, you will still know what the country in general will be doing, and so you will be able to make good investments and gain great wealth.

Finally, I am an agnostic and don't believe in astral projection or spirits and such.  The above was a flight of alcohol fueled fancy from my yoot.

We are all on a very slow, one-way time machine, it travels at 1 sec/sec. -- John DeChancie, author and mensch.

For starters, I didn't belive in time travel until I took a bunch of physics classes that came to an end last semester.

Time dialation is possible and has been proven. This is the idea of time slowing down due to the fact that a reference frame is accelerating or slowing down in comparision to another. For example. NASA, I believe, did this testing with watches. They set one watch on earth and the other in an F-14 (I believe it was this plane.) Anyways, the F-14 did a series of thrusts that caused serious acceleration and slowing. This in turn changed the f-14's watch's reference frame so it didn't act like simple physics. When the test was over both watch's set side by side were a couple of seconds off each other. Then the watch's were switched and the test ran again. When it was over the watches wer just about right on with eachother. This is a very simple explination of the results. To see how this was possible search on the internet for time dialation and to see an example try to find the train example.

As for time travel I believe it is possible to go forward in time. But forward in time is not how most people think of it. Once you near the speed of light without going over it and do some speeding ups and slowing downs to separate your referance frame you have a more dramatic case of time dialation. The reson it happens so much faster than the f-14 experiment is due to the fact that time travel is based on the speed of light. (you can look up the equations with gamma or just picture the train example that I mentioned) So what really happened when you went forward in time is you just slowed down your aging with respect to the other reference frame. (In this case Earth). Now I know what you are going to say. "Earth has acceleration like gravity and centripital." But keep in mind, gravity doesn't make us accelerate unless we are falling and the fact that we are going in an orbit is a small acceleration compared to what you would be doing in a space ship.

Going back in time is sort of a contradiction because to do it you would have to go faster than the speed of light and that is supposed to be impossible. I can't really explain how going back works very well so I will skip it.

Now the real question is what happens is you just go the speed of light exaclty? While your at the speed of light you are moving at a constant rate and nothing impressive happens, but when getting to the speed of light you have to accelerate up to it and if the closer you are to the speed of light the faster dialation happens then you have this limit. and unfortunatly the limit doesn't exist from the equations if you actually reach the speed of light. So in theory you would go an infinate amount of time forward when you hit the speed of light. This also complicates going back in time when you think about it.(going back it time with the equations given to us by the great, simply implies the square root of a negative number, which in turn is and imaginary number)

Pardon the spelling, I'm going to be an engineer not an English major.  

I flew down to Mississippi this week, and when I got off the plane, I could have sworn I was back in 1974.  Does that count?

A wise man once said(don't ask me which one)that the only thing that seperates man from animal is the consept of time. There are various plains of existence. Past present and future. They are all going on in the same areas at different times. With this I mean for example. I'm sitting here at my desk in my house now while in another plain of time this area where my house is at is covered in water.In a future time my house might not exist for some unknown reason. In this theory time (past present and future) keep reacurring on a loop. The only thing that keeps my house from being under water while I'm here is time. The only reason my house is here is time. Heres one for those scholars out there if I was to travel back in time to see my past self or forward to see my future self. Could 2 versions of my person exist in the same time loop? Is this possible. This comes to mind after seeing the movie "Timecop" where 2 versions of ones self could exist at the same time,but could not touch each other in essence sharing the same exact space. This theory of time travel has always been very interesting to both myself and my father. CAPITALIST

If I could time travel I'd want to go back and tell our Founding Fathers about the total lack of respect for The Bill Of Rights that our liberal government has in my time. About the tearing apart of the first amendment by Campain finance reform. The weakening of our Second amendment rights and the persecution of peacful gun owners. Could you imagine what Thomas Jefferson would say about all this? Maybe if this happened they could wright in some safegaurds to keep the desinagration of our Rights from happening. When I see every year that another one of our rights has been taken away it makes me sick to my stomach. What would any of you do if you could time travel to change things for the better(seriously)?

Yes, it would be great to be able to advise the Constitutional authors of the shit that later politicians would pull.    

If they really knew what would happen, they may have rephrased the 2nd to say something like this:

"The right of the individual people to own and use any firearm of any type, and any ammunition for same, for any lawful purpose, shall not be abridged or infringed in any way by any man or agency of any government for any reason.  Nor
shall any law be passed restricting the right of the people to carry any firearm in any public place."

I'd like to think they would also add in a clause that requires all people to show proof of ownership of a firearm, by BRINGING IT WITH THEM, when they vote, or they would not be permitted to vote.    Vote with your guns, you might call it.   Far more sensible than 'motor voter'.

Maybe they should have taken it a step further and required every person to be trained in firearms use at an early age, by public school, and then required the head of each household to keep a firearm and ammunition in his house, ready for use.

If we had time travel, this would be a worthwhile adventure.

CJ

Most movies seem to forget that we are on a planet moving around a sun in a universe that is expanding.  So say you go back in time a few days.  You would be on the earth since it was at a different location a few days ago.  So not only do you have to travel in time but you would also have to travel in space to stay on the same position on earth.

To see yourself in the future you would have to follow a certian path and you would know if that path was successful before you finished it. let that blow your mind. For starters you would have to dialate yourself (read above for explination). Then you would be in "the future". Now if you landed back on earth and went searching for yourself two things could happen. You would find yourself or you wouldn't. This is the same moment you would realize whether or not the rest of your trip went as planned.

If you did find yourself. you would know that the trip worked because you were able to go back in time after you visited your "future self" and grow old with the world. This is the only way you would find yourself. Then you would also know that your trip back is going to be same and successful. If you did find yourself, here is the big question. Would your future self know what you guys are going to talk about? You might say yes because it is in his past, but you could also say no because, it is just now happening for him.

If you read in the archives somewhere that you disappeared a long time ago then you would realize that your trip isn't going to finish as planned. you future present would be written in the archives of the past. (think about that one) So now you are left with two options. you can try to go back and not make it or you can simply reintroduce yourself as the found non-aged man that was lost for so long.

Only if the pod your in is stationary and right now the only theoretically way to time travel is to get in a rocket ship. In which case you could see the earth to land on it. The ones with the spinning balls would only work if you could take a few million G's.

I have read way too much of Einsteinian SRT and the related Hawking BS to even give an objective opinion here.

SRT “proves” that time can be slowed.  This is supposedly “proven” by the shortening of the half-life of muons traveling at near light speeds.  The problem with SRT is that the theory itself is it's own nemesis until you can have an observer (aka timer which measured the muon’s half-life) outside the inertial reference frame of the experiment. The understanding of inertial reference frames is a bit complicated and I’m not going to go into that. I will generalize with this:

You are given a theory (SRT) or a number of theories that state that time is a variant with velocity and differs to observers in different reference frames.
1) Would not you assume that you need multiple observers in these different reference frames to prove the theory??? YES! Therefore, the "two atomic clocks" experiments are total BS. You cannot run clocks through a magnetic flux at different velocities and then blame the time dilation on the velocity of the airplane and the “relativity” to the observer on earth. No one has performed an experiment to this day correctly to absolutely prove SRT.
Crap!! Time does not dilate as you approach C. Although, I will say that SRT has done some good in modeling particle behavior here on earth I do believe the models are interpreting the physics involved correctly,

Now lets touch on space-time...The inter-woven fabric of Star Trek and other non-sense…  Gravity IS responsible for distorting space, and this opens up some theories for those Christopher LLoyd time-travel dreamers.
1) Does gravity distort space only?
2) Does gravity distort the time element also? Well there you have it, build yourself a gravity generator and time inside the super dense gravity field will be manipulated.
BUT, does this allow for time TRAVEL??? Does speeding up time up actually bring you into the future? YES it does (if it can be done). Does slowing time down actually bring you into the past? NO it does not....EXCEPT to the outside observer who has been experiencing time in the normal sense. So you have gone “into the past” from time “A” when you fired up your gravity generator and time had slowed compared to the outside observer who has been experiencing time in the normal sense. It is totally impossible to go back in time BEFORE the super-duper gravity generator was ever built.
3) Even if gravity distorts space ONLY……Can space distortion be used for time travel? Here is the ultra gay Hawking analogy: Lets model our space-time universe as a single sheet of paper.  Lets imagine that earth is on one corner of the sheet and Chewbacca is on Endore, at the other corner of the sheet.  Normally, it takes 3,200 years to get to Endore in the current model NASA Space Shuttle. How do we get there in a reasonable amount of time?  Ohhh, that’s easy! Lets introduce enough gravity to bend the space-time “fabric”.  Now imagine the sheet being bent so that the two corners are bent close together. Can we now jump OUTSIDE THE SHEET across this undefined area of nothingness from Earth to Endore?  Well WTF is the area outside of the space-time model?? Heaven? Hell? Purgatory? From my experience, it probably resembles Kansas.  [:D]

Rather than think of time travel in HG Well's terms, how about thinking of it in (Original movie) Planet of the Apes terms?  That we are able to "skip" time and end up in the future (with no way back)?  I bet we'll see the outline for this one during our lifetime.

Sancti Thoma adjuva me...

I will now be speaking under the authority of the unam Sanctum in terms of philosophy and theology:

Time itself is a human construct.  It based either upon the lunar or solar year.

The Blessed Trinity lives "outside of time" as the  Father, +Son and Holy Spirit are not bound by time.

During the mass the Church proclaims that we celebrate the Eucharist with "the Church on earth, all the saints and all the hosts of heaven", so the baptized essentially partake of a feast which includes those who have come before us and those who will come after us.  As a matter of theology, we participate in "diachronetic" (both ways) time.

Therefore, every Sunday and feast day the Church experiences a bit of "time travel".

Pax Vobiscum,
Padre Schnert Oblate O.S.B.

Sounds like you're trying to define a new kind of physics using the model we use in today's world where time travel isn't possible. Copernicus found that he couldn't explain the way he saw the heavenly bodies move by using  the current paradigm of the earth being the center of the universe, so he came up with a new one. I think that if time travel ever became possible (in either direction), your 5:00/4:30 example would be irrelevant, because in order for time travel to work it would have to be. There's a reason it's called the time paradox, after all - if your mission was to go back and kill your grandparents, you should never be born if you succeed. But the fact that you exist to go back and kill your grandparents proves that you will exist, even if your antecedents are dead.

From what I've learned, time and distance are really just 2 sides of the same coin. "Short" galactic distances are measured in light-minutes, which are really nothing more than minutes with a vector attached to them. One can go 8 light-minutes and reach the sun, or one can send a camera 8 minutes into the past or future and himself as he was/will be.

I'm building a blue British Police Box.

AR-18 = Dr. Who?

What do I think of time travel, well I would head back and by all the 1st generation colt Saa I could get to sell to all these cowboys of today, then head back and by all the pre-bar ar's I could load up. After that I think I would load up all that could go and head to Nam in early 60's and finish that before it started and save the lives of a lot of really good friends!

I got one of those (time-machines). It doubles as my transport many a weekend I make the 3.25 hour drive to farm in about 1.9 hours. Does that count?

Mike

Man this gave me the MOTHER of all headaches...

Your antecedents would be dead, and you would have no connction with the world you return to, like in "It's a Wonderfull Life"  You would never have been.  Yet you still existed.  Sounds like a parallel timeline, to me.

I like the vector angle (no pun intended).  So how do you manipulate the vector, Victor?

Shirley, you can't be serious.

"Time travel" eh????

You've heard of the expression "time flies" right???

Well, I guess we can assume when time travels, it uses an airplane.

[:D]

If time travel is possible, where are the travellers?  They should be right around here somewhere.

Then again, we're ALL travelling into the future.  For a while.

Time is measured by the speed of light. It is the great universal constant by which all else is measured. You must understand this to begin to understand both time and relativity. It is because of the fact that time is measured by light speed that Einstein was forced to come the conclusions he did about relativity. Gravity waves also travel at the speed of light, FWIW.
Anyhow, "imagine if you will" that someone in a railroad car shines a flashlight against the  wall while moving. The light clears the distance between him and the wall at light speed and hence a set amount of time. An observer outside the car sees the light go the same distance+the distance the car has traveled. It has therefore taken longer from his frame of reference. This difference is miniscule at such "non-relativistic" speeds. Clearly though, you can see how large a difference this is at speeds approaching that of light. At such speeds object contract and increase in mass. All these changes occur exponentially and approach infinity near light speed. This is the reason that Einstein concluded that light speed could not be exceeded. An object would become infinity heavy requiring infinite amounts of energy to push it, it would become infinity contracted, and time would be affected infinity.

As for time travel, per se, it seems conceivable if you consider the universe as a cube of three dimensions moving through time as a fourth dimension. Other dimensions mave provide shortcuts through the ones we currently inhabit. Maybe in tens of thousands of years if we're still here.

The problem is that the theory of time is totally mixed into religion. Eastern religions, both normal like Hindu and political like liberalism believe in time as the loop or constant circle.
Christian and jewish and like faiths, as well as conservatives, think time is an ever growing river, leading towards an ultimate state of being or knowledge.
The two views color every facet of time theory and thus time travel, even in fiction.

Einstein concluded that light speed is constant.
Time is the variant.
The railcar analogy C+V or C-V applies on the observer.
If the railcar is traveling at velocity "V" and a guy with a flashlight points the light towards the direction of the traveling train.....is the light propagating from the flashlight at C+V???

It is not possible for any mass to ever accelerate to the speed of light.  You haven't mentioned mass dilation:  as velocity approaches the speed of light, mass approaches infinity (implying energy increases to infinity).  That means you can keep on adding energy and velocity will almost quit increasing as the energy goes into "creating" mass (E = mc^2).

the speed of light is constant to all inertial frames.  that is one of the postulates of SR

exactly!

E=mc squared does not apply to the situation you are describing. It applies to the conversion of mass to energy such as occurs in fusion or fission reactions. Note that the speed of light(c) squared is a huge number. Hence the incredible amount of energy that is released from a small decrease in mass such as occurs in a nuclear weapon.
Near light speed, mass is approaching infinity but there is not a conversion of energy to mass or vice versa. It simply means that a huge amount of energy must be applied to maintain speed. Remember that space is not a perfect vacuum.

Just moved this topic from GFD to GD. [:)]

Tyler

My Guesses:

1. To get something to go light speed would take like, all of the energy on the planet.
and you would end up on freaking Beetlgeuse with no power to get home- unless you install a Mr. Fusion.

2. Time is mans invention, the simplest explanation that it was even created was to make sure he got to the range on time.

2a. If time is mans invention, what exactly is it that causes us to "go forward"(moment to moment)and is there a certain size to the length of "moments" in time that can be measured-lets find it and attach some shaped charges to it.

3. rotational machines would not work as the rotational kinematics would tear it apart-even if perfectly balanced-and I know there is nobody here that is balanced.

4. is there really  good reason to go back?- how do we learn from our mistakes if we never make them.

5. if the universe is infinitly big, where is it?

6. give me more beer and I will come up with more theories.

"Time flies like an arrow."
Fruit flies like a banana.

Yes, you're right.  Thanks for the correction!

Edit:  Actually you're right about the energy not turning into mass, but space IS assumed to be a vacuum in the lorentz transformations.  So energy is not necessary to maintain the near light speed travel--just to continue accelerating.