time reversal

[kotss]

Originally posted by: malak
Let me get a little more detailed here.

First off, travel is an inappopriate term. The past and future are not destinations that exist. You can't "go" to them.

Secondly, there is a way to arrive in your future with it seeming like you traveled to the future, but in reality you aren't. It's not so much a matter of going anywhere or speed, it's a matter of encapsulating a certain point in space and stopping time. Time all around you moves still so once you start time in that point again, you are in the future. But it's not travel, it's not going anywhere, and it's still not possible either. You can still freeze yourself the old fashioned way.

Journeyman Project anyone?

Have you ever heard of Relativity and Time Dilation, which has been proven?
So when a spacecraft is made that can go relativistic speeds (and real meaningful effects of time dilation
can be observed) you would travel relativistic speeds and time relative to others would be different for the
those on earth and those in the spacecraft. Do you discount that as they travel, time relative to anybody
not travelling at relativistic speeds is going at a different rate?

 

[Looney]

Originally posted by: Anubis08
Nope. First you could never attain that speed, and second, if we could theoretically in the future come back, we would hopefully be smart enough not to because of the catastrophic impact it might have. After all, short of mass changing into energy, we have never seen matter created or destroyed. You would have to create matter in our time and destroy it in your own to go back in time. That could hsve some very dire consequences as well as the loop paradox where in one spot in time you will forever maintain that loop. Very complex and doubtful.

Theoretically there are a particle known as tachyons that travel faster than the speed of light. And i don't know why you would need to 'destroy' the matter in our time to go back into previous time... do we destroy matter as we go forward in time? You're thinking of time as segments that are seperated by intervals or something, it isn't.

 

[Anubis08]

Originally posted by: ghost03
There is one way that is theoretically possible. Construction of a wormhole theortically would allow you to go back in time as far as the creation of the wormhole. Construction of a wormhole of course would require many more resources than we are capable of, and probably won't be capable of for a long time.

That relies on the fact that wormholes exist. This could be some quacks way of getting recognized as there is in no way any shred of evidence that they exist. Again, it goes to the creation of matter.

 

[Malak]

Originally posted by: kotss

Originally posted by: malak
Let me get a little more detailed here.

First off, travel is an inappopriate term. The past and future are not destinations that exist. You can't "go" to them.

Secondly, there is a way to arrive in your future with it seeming like you traveled to the future, but in reality you aren't. It's not so much a matter of going anywhere or speed, it's a matter of encapsulating a certain point in space and stopping time. Time all around you moves still so once you start time in that point again, you are in the future. But it's not travel, it's not going anywhere, and it's still not possible either. You can still freeze yourself the old fashioned way.

Journeyman Project anyone?

Have you ever heard of Relativity and Time Dilation, which has been proven?
So when a spacecraft is made that can go relativistic speeds (and real meaningful effects of time dilation
can be observed) you would travel relativistic speeds and time relative to others would be different for the
those on earth and those in the spacecraft. Do you discount that as they travel, time relative to anybody
not travelling at relativistic speeds is going at a different rate?

As it pertains to the OP, none of that really matters, since this will never result in reversing time. It will only slope closer and closer to 0, never reaching it. And this is not time travel as hollywood defines it. Travel is still a bad word. Time goes the same speed for everyone, and the people in the craft would still be in the same time as everyone else, neither moving away nor towards. There is no escaping time. All they are doing is slowing down the effects of time on themselves.

 

[deveraux]

Originally posted by: kotss

Originally posted by: mwmorph

This is correct as you are travelling relative to earth and the moment you run/walk or have any relative motion whatsoever to the ground, you move slightly forward in time, and as Cattlegod has said, you still are on the same time plane.

From what I know of pure relativity, speed of light is a limit and it works both ways. Particles already travelling faster than light cannot slow down below the speed of light and particles below the speed of light cannot speed up above the speed of light. Relativity does not say that particles above the speed of light does not exist. Theoretically, if you are already faster than the speed of light, you do not go "forward" in time but instead your "forward" would be our "backward" i.e. travelling back in time.

And time definitely does exist since the 2nd law of thermodynamics has already provided an arrow in time, hence a clear distinction between past and future. Oh, and another consequence of time not existing is that relativity would be wrong, as it relies on the time being the 4th dimension.

I haven't done relativity in a long time, so if some of what I said is wrong, please forgive me.

Let me know where you heard of particles going faster than the speed of light. I would be much
interested. The only thing I have ever heard of was the Tachyon, but that has since faded from most
modern theories. Most accounts of relativity I have read, never mention anything about FTL particles.
The only thing I know that has been considered to be travelling backward in time is anti-matter.

It was told to us by my friends physics lecturer. However, no one has found particles that are faster than light (AFAIK). But anyone in physics knows that if the laws of physics do not preclude it from happening, it is very likely to happen.

 

[grant2]

Originally posted by: Hardcore
You're thinking of time as segments that are seperated by intervals or something, it isn't.

Eggheads have discovered time DOES advance in discrete intervals, much like the ticking of a clock.

 

[f95toli]

No, that is not correct, there MIGHT be a smallest "time step" (maybe the Planck time) but no one knows for sure.
This is yet another "hot topic" in physics, maybe we will know in a few years.

 

[kotss]

Originally posted by: malak

Originally posted by: kotss

Originally posted by: malak
Let me get a little more detailed here.

First off, travel is an inappopriate term. The past and future are not destinations that exist. You can't "go" to them.

Secondly, there is a way to arrive in your future with it seeming like you traveled to the future, but in reality you aren't. It's not so much a matter of going anywhere or speed, it's a matter of encapsulating a certain point in space and stopping time. Time all around you moves still so once you start time in that point again, you are in the future. But it's not travel, it's not going anywhere, and it's still not possible either. You can still freeze yourself the old fashioned way.

Journeyman Project anyone?

Have you ever heard of Relativity and Time Dilation, which has been proven?
So when a spacecraft is made that can go relativistic speeds (and real meaningful effects of time dilation
can be observed) you would travel relativistic speeds and time relative to others would be different for the
those on earth and those in the spacecraft. Do you discount that as they travel, time relative to anybody
not travelling at relativistic speeds is going at a different rate?

As it pertains to the OP, none of that really matters, since this will never result in reversing time. It will only slope closer and closer to 0, never reaching it. And this is not time travel as hollywood defines it. Travel is still a bad word. Time goes the same speed for everyone, and the people in the craft would still be in the same time as everyone else, neither moving away nor towards. There is no escaping time. All they are doing is slowing down the effects of time on themselves.

Who said it was relevant to the topic of the thread, just like so many other threads this contains fibers that
branch out all on their own. How is going near the speed of light staying put and encapsulating space?
Why is it the most predominant theories call it space/time and not just space?
[/fun][/sarcasm]Have you not heard of the Chroniton particle? It is the particle that mediates time.[sarcasm][fun]
Are you closer to zen buddhism in your philosophy?

 

[SagaLore]

Originally posted by: kotss

Originally posted by: malak
No, you cannot go back in time. Time does not exist. There is nothing 2 seconds from now in either direction of our measurement. You cannot go to what does not exist.

How is it, that time does not exist. Please explain in detail.

Time is actually the wave, or frequency, of spacetime. You can't travel back in time because there isn't anything to travel to - all there is, is now. You can't even travel ahead in time. At most you can relatively change the speed of spacetime within a confined area so your perception of time outside of the confinement is either faster or slower. I believe this is what we'll find if we encounter a wormhole - it can connect two points in space, perhaps with a faster or slower "clock speed", but it will never connect two points in time.

 

[kotss]

Originally posted by: SagaLore

Originally posted by: kotss

Originally posted by: malak
No, you cannot go back in time. Time does not exist. There is nothing 2 seconds from now in either direction of our measurement. You cannot go to what does not exist.

How is it, that time does not exist. Please explain in detail.

Time is actually the wave, or frequency, of spacetime. You can't travel back in time because there isn't anything to travel to - all there is, is now. You can't even travel ahead in time. At most you can relatively change the speed of spacetime within a confined area so your perception of time outside of the confinement is either faster or slower. I believe this is what we'll find if we encounter a wormhole - it can connect two points in space, perhaps with a faster or slower "clock speed", but it will never connect two points in time.

Time is actually a dimension. It used to be seperate until Einstein united it with space to call it space/time.
Time itself is relative to the person who is measuring it. My own clock and yours are not necessarily in
agreement especially when high speeds or intense gravity are concerned. Since it is interwoven with
space it is affected by gravity and because as you move faster you gain energy/mass you are causing the
same effect in essence and you cause space/time to "warp". Thus causing a change in the relative
measurement of time and distance and mass. Each persons perception of their own time relative to them
is no different it is just different relative to each other.

[Theory]
According to wormhole theory you could actually connect a wormhole to two different points in time as
well as space. You create a wormhole that connects two different points in space, then take your ultra
massive spaceship to the opening of one end and as the wormhole is attracted to your massive spaceship
you accelerate to relativistic speeds causing time to warp. You travel out and then back again in order to
allow for a meaningful warp. Once you bring the wormhole back to its starting point you now have a
wormhole that connects to 2 different points in space and time. (In this statement I use the word warp
to mean dialation.)
[/Theory]

I do not go along with the statement "Time is actually the wave, or frequency, of spacetime."
This would imply that time is a property of space and not an integral part of space.

Now, we could be hashing hairs and saying the same thing in two different ways. The problem with some
of this discussion is that not is all known even by the big wigs in the study of physics. Some things have
been verified, which lends to the credence that the theory that is supported by the empirical data is sound.

Now for the ending statement that is a pun.

Only time will tell.

 

[Jack31081]

I've read a lot about time travel and done a few reports, and here's the info I have to offer:

Our current state of knowledge regarding time and space dictates that it is impossible for anything travelling slower than light to ever go back in time. As a mass accelerates towards light speed, its density approaches infinity. A singularity is reached at 'c' (speed of light) when the density would be infinite (volume reaches zero, and any mass divided by zero is not a good thing). Also, your relativistic mass becomes infinite, and no amount of energy would ever be able to accelerate you any further. Therefore, no faster-than-light travel means no going back in time for us.

However, no current scientific theory prohibits travelling faster than light. Only accelerating from one side of the light-speed barrier to the other. This is how we got the idea of "faster than light means back in time" in the first place. If something is going faster than light, the equations work just fine, only the time 'variables' are negated.

The hunt is on right now for particles that are created going faster than light and go faster than light forever. These particles would never be able to slow down to a speed slower than light, and they actually go faster when less energy is applied to them. In fact, it is entirely possible that anti-matter is not really 'anti-matter', but rather particles of regular matter that were created going faster than light, and hence, backwards through time. Very cool stuff, but it would take very long to explain it all, and I'm at work right now.

This doesn't rule out travel to the past entirely though. In fact, there is one way to go back in time that is scientifically sound, if a bit impractical. All you need to do is line up about 10,000 neutron stars in a cylinder shape and get them all spinning in the same direction. Space-time would be distorted in such a manner that if you could navigate through the distortion field, you would be able to access any area of space-time, here, there, past, future. Only problem is, you'd need a craft that can withstand the enormous gravitational forces. The best shape for such a craft....just happens to be a saucer shape.

Then there are wormholes, but they don't exist long enough and they're infintesimally small.

 

[argoldst]

Well, the answer to the question is yes and no.

It all depends on your definition of traveling through time. If you are referring to the ability to see the past, then yes, it is possible.

If you are talking about the ability to interact with those in the past or future then no, it is impossible.

Let me attempt to explain.

Actual existance time- Time itself, or the existance of something at an exact moment at an exact location cannot be altered. Basically, once something is done, it cannot be undone or changed. So any ideas of time travel like in the movies is just impossible.

What we see as time- Our main perception, sight, is based on images of light that obvisouly travels at the speed of light. If an event occurred such as a ball hitting you, and you traveled 10 times the speed of light for 1 second (in a straight line away from the actual event), and you were capable of seeing that distance, you could, 9 seconds later, watch yourself get hit with the ball. So basically, if you travelled the speed of light away from an event, you could go back in time to see the past.

Now if you were to go faster than the speed of light toward an event, you would actually be seeing things in a form of "fast foward" starting from the past and ultimatily arriving at the "actual existance time".

Time travel or the view of time in the future is impossible.

Hope that clears it all up

 

[argoldst]

To give another quick example, if we were watching a planet that was 1 light year away in which people x live were to explode this second(the actual time the people on planet die) we would not see it for one year. We will call this time of explosion "explosion time"

At the same exact explosion time, people on earth would be viewing the past of the planet and people x or basically the equvilent of explosion time minus 1 year.

We would be watching what actually occurred one year ago.

In fact, we on earth would not be able to see the explosion until one year after the explosion time. People x would be dead for over year before we even saw it. So although we live in what we term as the present, what we percieve with our eyes, is not always present time.

Boggles the mind huh?

 

[Jack31081]

You could always take that to the extreme and say we actually live in the past, as all we perceive and sense took place in the past. Reminds me of a line from a Mitch Hedburg standup routine:

"One time a guy handed me a picture of himself, and he said, 'Here's a picture of me when I was younger.' Every picture of you is of when you were younger. 'Here's a picture of me when I am older'. You son of a bitch, how'd you pull that off? Let me see that camera..."

Also, if you subscribe to the notion of a 4 dimensional enclosed universe (shaped like a doughnut), you could theoretically have a telescope so powerful you would see the back of your head.

 

[f95toli]

Originally posted by: argoldst
Basically, once something is done, it cannot be undone or changed. So any ideas of time travel like in the movies is just impossible.

W don't know that, that MIGHT be true but no one knows for sure. Again, we simply don't know. The only thing we can sure of is that nature does not care about what we think is "reasonable".

It is important to remember that most modern physics (quanum mechanics etc ) defies common sense and I am not sure that time travel would be more "strange" than some of the things that goes on in labs around the world every day.

 

[mwmorph]

yeah, but then waht happens, if say you murder your previous self? does quantum physics just not let it happen somehow?

 

[imported_jb]

any of you people heard of some dude from UConn who said he can solve this problem?

 

[SagaLore]

Originally posted by: jb
any of you people heard of some dude from UConn who said he can solve this problem?

No, please elaborate.

 

[imported_jb]

uh ok.
this dude, whom i just saw a Science Channel show on (that is a few years old), says that time travel will occur in our lifetime. he has it all worked out, with barely any new theories (if any). he plans to put a high powered laser into a loop, which will twist space-time, then drop a neutral particle in, and whiz it away to the past.
it is from a few years ago, not sure if there's anything new on it.

 

[SagaLore]

Originally posted by: jb
uh ok.
this dude, whom i just saw a Science Channel show on (that is a few years old), says that time travel will occur in our lifetime. he has it all worked out, with barely any new theories (if any). he plans to put a high powered laser into a loop, which will twist space-time, then drop a neutral particle in, and whiz it away to the past.
it is from a few years ago, not sure if there's anything new on it.

How does one put a laser into a loop?

 

[imported_jb]

http://temporology.bio.msu.ru/EREPORTS/mallett.pdf

 

[sao123]

I've read a lot about time travel and done a few reports, and here's the info I have to offer:

Our current state of knowledge regarding time and space dictates that it is impossible for anything travelling slower than light to ever go back in time. As a mass accelerates towards light speed, its density approaches infinity. A singularity is reached at 'c' (speed of light) when the density would be infinite (volume reaches zero, and any mass divided by zero is not a good thing). Also, your relativistic mass becomes infinite, and no amount of energy would ever be able to accelerate you any further. Therefore, no faster-than-light travel means no going back in time for us.

However, no current scientific theory prohibits travelling faster than light. Only accelerating from one side of the light-speed barrier to the other. This is how we got the idea of "faster than light means back in time" in the first place. If something is going faster than light, the equations work just fine, only the time 'variables' are negated.

The hunt is on right now for particles that are created going faster than light and go faster than light forever. These particles would never be able to slow down to a speed slower than light, and they actually go faster when less energy is applied to them. In fact, it is entirely possible that anti-matter is not really 'anti-matter', but rather particles of regular matter that were created going faster than light, and hence, backwards through time. Very cool stuff, but it would take very long to explain it all, and I'm at work right now. Someone help me with the rest of the idea... it came from the hawkings book Universe in a nutshell.

This doesn't rule out travel to the past entirely though. In fact, there is one way to go back in time that is scientifically sound, if a bit impractical. All you need to do is line up about 10,000 neutron stars in a cylinder shape and get them all spinning in the same direction. Space-time would be distorted in such a manner that if you could navigate through the distortion field, you would be able to access any area of space-time, here, there, past, future. Only problem is, you'd need a craft that can withstand the enormous gravitational forces. The best shape for such a craft....just happens to be a saucer shape.

Then there are wormholes, but they don't exist long enough and they're infintesimally small.

This would seem to be a parallel to something i read about the event horizon of a black hole? I dont remember everything, but it has something do with a pairing of a particle with a virtual particle on each side of the horizon, one falls into the black hole, and the other escapes from it. Also the particle and virtual particle have opposite spin.

 

[JohnCU]

I just don't see how it could work. Like, going back to yesteryear to hear an FDR speech...it's not possible. That's all gone.

 

[Jack31081]

Originally posted by: mwmorph
yeah, but then waht happens, if say you murder your previous self? does quantum physics just not let it happen somehow?

There are a few solutions to the 'grandfather paradox', which you've stated in a nutshell. Basically, if you go back in time and kill your grandfather before your father is born, wouldn't you not have existed to go back in time in the first place?

The one I like the best is that your existence is proof that you cannot kill your grandfater before your father is born. Let's say you travel to the past to kill your grandfather. Well the past already happened, and since you're here, you obviously didn't succeed. Maybe you couldn't go through with it. Maybe you couldn't find him. Maybe your father was conceived shortly before you killed him. Maybe you died yourself before getting to him. Who knows, but whatever happened, you didn't negate your existence, because you exist.

Wrap your head around that

Think about it like this. TIME is a straight line, like a rope. Each person's TIMELINE is a string on that rope. Most will follow the rope and go straight. But the string of those that go back in time loops around and goes to some previous part of the rope.

Maybe that doesn't help. oh well.

 

[SagaLore]

Originally posted by: Jack31081
The one I like the best is that your existence is proof that you cannot kill your grandfater before your father is born. Let's say you travel to the past to kill your grandfather. Well the past already happened, and since you're here, you obviously didn't succeed. Maybe you couldn't go through with it. Maybe you couldn't find him. Maybe your father was conceived shortly before you killed him. Maybe you died yourself before getting to him. Who knows, but whatever happened, you didn't negate your existence, because you exist.

That's the one I like the most. It makes sense. That was used in the movie Time Machine, which is why he couldn't save his wife - otherwise he had never built the machine to go back and save his wife. So whatever your attempt is when going back in time, everything has already played out to bring you to that moment and the spacetime continuum keeps itself stable.