How do you FTL?

[IDMclean]

That's fine to, and more than likely that kind of thinking will get us somewhere we didn't envision with our current understanding.

 

However for now, I go with the Concept of Fundementals on this one. The basic, as I understand it, definition of a fundemental is something which is irreducable. It is circularly defined. What is energy? The potential for motion. What is the potential for motion? Energy.

[Jay-qu]

Maybe there is an explanation using much deeper physics of why photons are limited to c. Obviously well outside our current understandings. I just think that at some point there has to be "It is that way because it is". Its not like we can come up with a theory that will explain itself. I just think there will always be the question of why, no matter how deep we go.

[EWright]

Maybe there is an explanation using much deeper physics of why photons are limited to c.

 

Or perhaps not so deep.

[TheFaithfulStone]

Or perhaps not so deep.

 

I'll bite. What's the explanation then?

 

TFS

[TheFaithfulStone]

Warning: Topical Post Ahead

 

Okay, so some guy on usenet got really indignant at the suggestion that the Alderson Drive wouldn't allow closed timelike curves. I mean, I'm sure it would allow time travel, but I can't think of a way you could travel into your own past with it. Normally, of course, any method of FTL can be defeated if you can do it within any reference frame. The trick of the Alderson Drive is that once you go into the "tramline" that when you come out, your frame of reference is the same as the frame for the arrival point, and two points always share a frame.

 

So you can't pull the "passing space ship" trick there.

 

Check the diagram!

 

So normally, A can send a message to B FTL. C is flying past B at relativistic speeds. He sends a message to D FTL, and it arrives before A sent his message.

 

Now on an Alderson Jump, if C was flying by B, and managed to hit his Alderson Drive at exactly the right time, he would be "thrown" into A's reference frame, and come out just after A sent the first message.

 

Provided there is only a single tramline between any two stars (true, according to the book) you couldn't just use the same tram to effect a paradox.

 

I've been playing with the space-time diagrams for a while, and have been unable to concoct a situation where I need an additional limitation. Perhaps if I were to jump from Sol to Tau Ceti, then from Tau Ceti to Alpha Centauri, then from Centauri to Sol I could pull it off.

 

I need someone better at relativity than I am to show me how it's possible to travel in time with the Alderson Drive. Well - how it's possible to travel into your own past.

 

Okay, I got it. You need very quickly moving stars which are located very close to each other. Rare but possible.

 

A new what if. What if the reference frames of the Alderson points were the same as the stars they led to? That is if I jump from to C, I end up going faster relative to my original velocity. If I try to jump back (even if I do it right way, I end up coming back right away, but not arrive at the same point I left at (basically, where the position line for C/D crosses the A/B position line.)

 

Hmm... that could be interesting.

 

TFS

[EWright]

Warning: Topical Post Ahead

 

Okay, so some guy on usenet got really indignant at the suggestion that the Alderson Drive wouldn't allow closed timelike curves. I mean, I'm sure it would allow time travel, but I can't think of a way you could travel into your own past with it. Normally, of course, any method of FTL can be defeated if you can do it within any reference frame. The trick of the Alderson Drive is that once you go into the "tramline" that when you come out, your frame of reference is the same as the frame for the arrival point, and two points always share a frame.

 

So you can't pull the "passing space ship" trick there.

 

Check the diagram!

 

So normally, A can send a message to B FTL. C is flying past B at relativistic speeds. He sends a message to D FTL, and it arrives before A sent his message.

 

Now on an Alderson Jump, if C was flying by B, and managed to hit his Alderson Drive at exactly the right time, he would be "thrown" into A's reference frame, and come out just after A sent the first message.

 

Provided there is only a single tramline between any two stars (true, according to the book) you couldn't just use the same tram to effect a paradox.

 

I've been playing with the space-time diagrams for a while, and have been unable to concoct a situation where I need an additional limitation. Perhaps if I were to jump from Sol to Tau Ceti, then from Tau Ceti to Alpha Centauri, then from Centauri to Sol I could pull it off.

 

I need someone better at relativity than I am to show me how it's possible to travel in time with the Alderson Drive. Well - how it's possible to travel into your own past.

 

TFS

 

I guess I'm not seeing the potential for FTL travel here. You will never exceed the rate of a light beam leaving from your same starting point. Any other light beam is in another reference frame. You will always measure any light at c along your voyage and you will never exceed c physically.

 

While it is possible to travel into another's future (twins paradox) it is not possible to travel into their past.

[Little Bang]

I still think that the photon exists in every possible event instantly. It is only our observational abilities that limit the speed of light.

[TheFaithfulStone]

I know it's not REALLY possible. I just enjoy finding plot-holes in Science Fiction FTL drives.

 

Oddly enough, I was reading Wikipedia a few minutes ago, and it had this little throwaway sentence that I thought was interesting in the section about why 3+1 spacetime was special.

 

Basically, there is a 1+3 spacetime that's not totally impossible (that is, it's predictable and rational) but it requires that every particle have a velocity greater than c.

 

Interesting. Of course, it's still nonsense to have more than one time dimension.

 

TFS

[Jay-qu]

why? do you think that time is really all that different from any other dimension?

[TheFaithfulStone]

Why is it nonsense to have more than one time dimension?

 

Because causality becomes meaningless.

 

I guess in the example I cited (the 1+3) thing you can have more than one time dimension, but like I said, then everything has to go faster than c. And that's obviously not the case.

 

In another that's predictable, you can't have complex molecules, and that's obviously not the case.

 

Ergo, there is only one time dimension in this universe.

 

TFS

[EWright]

Why is it nonsense to have more than one time dimension?

 

Because causality becomes meaningless.

 

I guess in the example I cited (the 1+3) thing you can have more than one time dimension, but like I said, then everything has to go faster than c. And that's obviously not the case.

 

In another that's predictable, you can't have complex molecules, and that's obviously not the case.

 

Ergo, there is only one time dimension in this universe.

 

TFS

 

Time absolutely has more than one dimension. See my upcoming post in the new articles forum.

[EWright]

The reason we cannot travel faster than light outright is not due to a restricting property of light. Rather, the same fundamental property that restricts light speed, limits our ability to surpass it. See my Theory of Temporal Relativityto better understand this limitation.

[Pyrotex]

I'm glad you agree, it does have nothing to do with light at all. Most people can't see that. But to say "because they do" is saddly lacking of a more thorough reason as to why they do. How 'bout we just stop asking any scientific questions and explain everything with "because that's the way it is?"

And I agree fully. This was made clear to me in grad school where I studied Relativity. All that dilation and distortion and mass increasing and time shrinking has ABSOLUTELY NOTHING to do with light, per se. It is not a "property" of light that does all this. Light does not magically reach out make spaceships "short and massive".

 

There are two things which DO do this. The first is easy: geometry. Any given speed of light, as long as it is constant from all reference frames, will cause distortion as you approach that speed of light. Even 10 MPH. All you can know about that spaceship is what you observe. Observation is everything. What you "know" can only be what you observe, and observation is determined by geometry.

 

The second thing is NOT easy. WHY is the speed of light observed as constant from all frames of reference? It is THIS that causes our observations of time & mass distortion. It seems to be a built in property of Reality itself, the very fabric of space/time/jello. This is the mystery.

[Pyrotex]

Time absolutely has more than one dimension. See my upcoming post in the new articles forum.

This would be true IF AND ONLY IF time were a true physically measurable dimension like X Y and Z (distance).

 

You can take a stick of length L meters, and put it between two objects and determine whether or not the distance between the objects is less than, equal to or greater than L meters. Later, I can take the same stick and repeat the measurement as many times as I wish.

 

But you cannot take a stick of "time length" T seconds and hold it between two events and determine whether or not the time between the events is less than, equal to, or greater than T seconds. Later (hell, here's a paradox already!) I cannot take your same stick and perform the measurement again.

 

Once the two events have occured, they cease to exist and the time length between them is forever inaccessible. This is true for ALL events.

 

"Time rulers" do not and cannot exist, for time is not a static and palpable dimension as is length. Time is something else, a pause between event 1 and event 2 that we can only measure by observing event 1, triggering a series of identical micro-events (which I shall call "tics") at the instance of observing event 1, and then counting the number of tic events that occur prior and up to the observation of event 2.

 

We can record the number of tics. We can say "there were 25 seconds between event 1 and event 2" -- but we can never, never, never "GO BACK" and remeasure the time distance between event 1 and event 2 DIRECTLY ever, ever, ever again.

 

We CAN measure the time distance between RECORDINGS that we made of the initial events. But we are then literally measuring DIFFERENT events, the new ones manifested with our video tape (for example).

 

Given two events, how could there be a different dimension of time, when all time is (by definition) is the pause or delay between those events?????

[EWright]

This would be true IF AND ONLY IF time were a true physically measurable dimension like X Y and Z (distance).

 

You can take a stick of length L meters, and put it between two objects and determine whether or not the distance between the objects is less than, equal to or greater than L meters. Later, I can take the same stick and repeat the measurement as many times as I wish.

 

But you cannot take a stick of "time length" T seconds and hold it between two events and determine whether or not the time between the events is less than, equal to, or greater than T seconds. Later (hell, here's a paradox already!) I cannot take your same stick and perform the measurement again.

 

Once the two events have occured, they cease to exist and the time length between them is forever inaccessible. This is true for ALL events.

 

"Time rulers" do not and cannot exist, for time is not a static and palpable dimension as is length. Time is something else, a pause between event 1 and event 2 that we can only measure by observing event 1, triggering a series of identical micro-events (which I shall call "tics") at the instance of observing event 1, and then counting the number of tic events that occur prior and up to the observation of event 2.

 

We can record the number of tics. We can say "there were 25 seconds between event 1 and event 2" -- but we can never, never, never "GO BACK" and remeasure the time distance between event 1 and event 2 DIRECTLY ever, ever, ever again.

 

We CAN measure the time distance between RECORDINGS that we made of the initial events. But we are then literally measuring DIFFERENT events, the new ones manifested with our video tape (for example).

 

Given two events, how could there be a different dimension of time, when all time is (by definition) is the pause or delay between those events?????

 

Did you read my Theory of Temporal Relativity? (If not click my signature below to read it and join in the discussion there).

 

While I agree with some of what your saying, we can, in a way measure events repeatedly as you do with a yardstick. We simply use units of time measurement instead. Granted, we can't go back to repeat them. But if we conduct experiments or even do something as simple as follow baking instructions it holds that we are repeating time measurments consistantly. Additionally, units of length are variable under relativistic conditions as well. And experiments to prove them can not be revistited, but only conducted again (as with time phenomena) to get the same results. Granted, you can remeasure stationary objects with the same ruler, or moving objects on earth because compared to 'light speed' they are essentially stationary. But you could not make the same measurements with the rulers that were created the same length being used by two different observers under relativistic conditions by going 'back to the scene' and remeasuring either or have them agree on their measurements in the first place.

 

My argument, however, is that man-made units of time (those we choose to measure with) exist within the fixed framework of a larger universal time, which is constant. It flows at a specific rate, which limits light to the constant speed at which we measure it. I'd be interested in your views in the thread on that discussion (click signature below).