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Other Discussion Boards => Technology, Science & Alt Science => Topic started by: optimisticcynic on July 22, 2009, 03:14:47 PM

Title: relativity.
Post by: optimisticcynic on July 22, 2009, 03:14:47 PM
OK I just had a random though about getting around one part of relativity wondering what other people thought about it.
Okay simplified version lets assume the universe is a hypersphere. (simplest form I could come up with) now if you have two machines that are traveling at .5c relative to each other.  both have an atomic clock on board. now as they go past each other they tell each other there time. now they both keep going until they meet each other on the other side of the universe. now if they then tell each other what time they have when they meet again. by doing this they could find out which one was going faster relative to the universe by which one was going faster relative to the universe. by doing a few of the test you could find out what rest to the rest of the universe is.
I am not an expert on relativity so I just was wondering if A. my understanding was correct and B. if it would work.
Title: Re: relativity.
Post by: Soze on July 22, 2009, 06:45:00 PM
they are moving at .5c relative to each other
Opposite directions?
A signal would be limited to c.

My thoughts are that since space time is curved, and so would the path through a hypersphere, that they are just making circles in space. Just because they don't curve in 3D space doesn't mean that they are constrained to an axis of the universe so to speak.  :P
By returning to the same spot via an extra dimensional circle, we can only measure how fast they travel relative to each other. And how could we know that they are traveling at .5c relative to each other?
Title: Re: relativity.
Post by: Euclid on July 22, 2009, 07:33:43 PM
OK I just had a random though about getting around one part of relativity wondering what other people thought about it.
Okay normally relativity says that although you go slower through time when you go faster it is not possible to tell how fast you are moving through space.
now lets so we have a universe that is a hyper sphere. now lets say we have just two objects in this universe. they are moving at .5c relative to each other. now they both have atomic clocks on board. now normally in order to check what is the time on the other spaceship at that moment you need to be next to it which requires you to accelerate after the other object. this is why you can no tell what true time is because be accelerating you cause relativity to affect you making it appear that you were the one that was moving and that you just decelerated. now how about instead you have it so that the go past each other and start there atomic timers. then you just wait till they meat again. since the universe is a hypersphere they will meet again then they both send a signal to tell how much time has past. now admittedly if you just use two objects you can just tell which one is going slower but if you used a lot of them couldn't you find out what was zero according to the universe?
I am not an expert on relativity so I just was wondering if A. my understanding was correct and B. if it would work.

lolwut?  I have no idea what you are trying to say.  Your sentence structure and spelling need some work.   :-\
Title: Re: relativity.
Post by: Soze on July 22, 2009, 09:58:25 PM
How long until Robosteve is unbanned?
Title: Re: relativity.
Post by: optimisticcynic on July 22, 2009, 10:38:44 PM
they are moving at .5c relative to each other
Opposite directions?
A signal would be limited to c.

My thoughts are that since space time is curved, and so would the path through a hypersphere, that they are just making circles in space. Just because they don't curve in 3D space doesn't mean that they are constrained to an axis of the universe so to speak.  :P
By returning to the same spot via an extra dimensional circle, we can only measure how fast they travel relative to each other. And how could we know that they are traveling at .5c relative to each other?
because we measure how much time has past to see which one had more time pass between when they leave and when they meet again. the one who has the most time pass will be going slowest in comparison to space.
Title: Re: relativity.
Post by: Soze on July 23, 2009, 05:00:31 AM
because we measure how much time has past to see which one had more time pass between when they leave and when they meet again. the one who has the most time pass will be going slowest in comparison to space.
But wouldn't that give you a ratio of speeds and not an exact speed, unless you had the diameter of the hypersphere universe?
Title: Re: relativity.
Post by: Robbyj on July 23, 2009, 05:52:36 AM
now if you have two machines that are traveling at .5c

by doing this they could find out which one was going faster

What?
Title: Re: relativity.
Post by: iznih on July 23, 2009, 07:53:04 AM
when they meet again, both machines would measure that the clock in the other machine was slower than their own clock. if there's a third observer at the meeting point he would see that both clocks are the same but slower than his own clock.
Title: Re: relativity.
Post by: optimisticcynic on July 23, 2009, 09:35:45 AM
when they meet again, both machines would measure that the clock in the other machine was slower than their own clock. if there's a third observer at the meeting point he would see that both clocks are the same but slower than his own clock.

but you would be measuring how much time passed between when they met. shouldn't you be able to figure out which one is moving faster according to space by which one by which one had the least time pass?
Title: Re: relativity.
Post by: iznih on July 23, 2009, 10:22:39 AM
what you read on the clocks depends on the inertial system you're in. no matter where you are, all other clocks will run slower than yours. you can only compare them with your inertial system. with respect to your system you can tell which one was faster, that should be possible. what i said about the third observer in my last post is only true if both machines move equally fast whit respect to that observer.
after thinking about the whole thing again, i think the problem is, that you think of space as something absolute and well defined. but somewhere you have to place a zero point and when doing that you chose a certain frame of reference. it makes no sense to call it moving or stationary without a second point of reference. but even then you can't tell which one is moving and which one is stationary. these frames of references are absolutely arbitrary and equally true as long as they are inertial systems. so only relative measurements can be made.

Title: Re: relativity.
Post by: optimisticcynic on July 23, 2009, 02:25:25 PM
but from what I understand about relativity there is a zero speed compared to the rest of the universe. it should just be impossible to find out what that is. the reason for this is lets say we knew what zero was compared to the universe. now as an object is moving at .5c compared to the rest of the universe. it would appear to that object that the rest of the universe was moving slower in time because information can't travel instantaneously however if they meet each other again without any acceleration then you should find that the less time has passed for the moving object then the object that was stationary. now if we consider a normal universe without boundary and infinite then this could not happen. however if the universe is not infinite but in fact a four dimensional shape so there are no boundaries it should be able to figure out which one had been going the fastest relative to the rest of the universe.
I am arguing that the universe does have a zero speed in reference to it but it is normally impossible to find because in order to do any test you would need to accelerate which would make the test not work.
Title: Re: relativity.
Post by: iznih on July 23, 2009, 04:01:07 PM
let's assume a zero speed exists (i'm not sure on that but as you said even if it is impossible to determine the frame of reference that does not move compared to the universe)
one object is not moving, a second object is moving. the second object starts it's jouney at 0.5c and it arrives back at the first object without accelarating (that also implies it is at full speed when it arrives).
object 1 sees a slower clock for object 2 and object 2 sees a slower clock for object 1 (the time difference is the same in both cases). it doesn't matter if one of them was absolutely at rest and what happens here would happen in any other inertial frame. so if object 1 was moving at a certain speed and object 2 would travel at 0.5c compared to oject 1 exactly the same observations would be made.

so even if you could conduct that test you would never reach a conclusion because what you could observe would also happen in any other inertial frame.
Title: Re: relativity.
Post by: optimisticcynic on July 23, 2009, 04:16:14 PM
let's assume a zero speed exists (i'm not sure on that but as you said even if it is impossible to determine the frame of reference that does not move compared to the universe)
one object is not moving, a second object is moving. the second object starts it's jouney at 0.5c and it arrives back at the first object without accelarating (that also implies it is at full speed when it arrives).
object 1 sees a slower clock for object 2 and object 2 sees a slower clock for object 1 (the time difference is the same in both cases). it doesn't matter if one of them was absolutely at rest and what happens here would happen in any other inertial frame. so if object 1 was moving at a certain speed and object 2 would travel at 0.5c compared to oject 1 exactly the same observations would be made.

so even if you could conduct that test you would never reach a conclusion because what you could observe would also happen in any other inertial frame.
no you don't look at how fast the object time is going at any instant you time how long it takes for the objects to meet each other again. when they are at pretty much the same point which ever one said it took the shortest time to meet again would be the one that is going the fastest. Even though to the one moving it appears as it was watching the one recede that the one that was moving was going faster then the other one in terms of time. but even it would see that it took less time for them to meet again then the other one did.
Title: Re: relativity.
Post by: iznih on July 24, 2009, 07:05:01 AM
so you place a third observer at the starting point who measures the time till the machines return?
Title: Re: relativity.
Post by: optimisticcynic on July 24, 2009, 08:56:01 AM
so you place a third observer at the starting point who measures the time till the machines return?
no you have them measure each other. as I said each one is moving at .5c relative to the to the other one.
once it has moved around the entire universe the measure how long it took for them to meet again. the one that says it took the least amount of time is going the fastest.
Title: Re: relativity.
Post by: iznih on July 24, 2009, 09:13:14 AM
ahh, now i get it. i'll think about that

edit: i checked with some literature and as far as i understood it it is not possible for any object to determine it's movement compared to an absolute space. the reason lies in the symmetry of physical laws concerning transformation in another system.
i think your experiment implicitely needs an additional inertial system in the last step, when you compare the measured times. in that case the whole experiment would be the same if you added the same velocity to the two machines and the third system so you wouldn't get any information on the absolute velocities. if you leave out the third system both machines would probably measure the same time. i'm not sure on the last two things, maybe someone with more knowledge on that can comment on that.
Title: Re: relativity.
Post by: optimisticcynic on July 24, 2009, 04:26:40 PM
ahh, now i get it. i'll think about that

edit: i checked with some literature and as far as i understood it it is not possible for any object to determine it's movement compared to an absolute space. the reason lies in the symmetry of physical laws concerning transformation in another system.

I know that in a normal infinite universe that it should be impossible I am trying to get around that and wondering if it would work
I don't know a lot about it. I spend a lot of time reading about it but I took Calc IV this year. in other words most of the equations are beyond me.
I am confused why you say though if you leave out a third system they would come up with the same time.

Oh one last thing, I sent this same question to robosteve and he said something that I can not confirm or disprove.
quote(
Also, this scenario cannot occur. They do not meet "on the other side" of the Universe - in order to define what "the other side" is, you need a reference point which would need to be one of the machines involved, and in order for one to meet the other it would need to return to this original point. This means that in order for one spacecraft to come back to meet the other, it needs to circumnavigate the entire hypersphere, which is prohibited by relativity because (if I remember correctly, and hopefully somebody who knows more about relativity can verify or refute this) a hyperspherical Universe is a black hole with a Schwarzchild radius in four-space and two singularities (a Big Bang and a Big Crunch). The time it takes a light ray to circumnavigate the hypersphere is equal to the total time the Universe exists for, so these two spacecraft would never meet.
)
also
(Yes, that is one possibility, which implies that it will also end in a Big Crunch. It is temporally infinite if and only if it is spatially infinite.)
Title: Re: relativity.
Post by: iznih on July 24, 2009, 05:17:22 PM
ahh, now i get it. i'll think about that

edit: i checked with some literature and as far as i understood it it is not possible for any object to determine it's movement compared to an absolute space. the reason lies in the symmetry of physical laws concerning transformation in another system.

I know that in a normal infinite universe that it should be impossible I am trying to get around that and wondering if it would work
I don't know a lot about it. I spend a lot of time reading about it but I took Calc IV this year. in other words most of the equations are beyond me.
I am confused why you say though if you leave out a third system they would come up with the same time.
forget that part about leaving out the third system, that was typing without thinking  :P
Quote
Oh one last thing, I sent this same question to robosteve and he said something that I can not confirm or disprove.
quote(
Also, this scenario cannot occur. They do not meet "on the other side" of the Universe - in order to define what "the other side" is, you need a reference point which would need to be one of the machines involved, and in order for one to meet the other it would need to return to this original point. This means that in order for one spacecraft to come back to meet the other, it needs to circumnavigate the entire hypersphere, which is prohibited by relativity because (if I remember correctly, and hopefully somebody who knows more about relativity can verify or refute this) a hyperspherical Universe is a black hole with a Schwarzchild radius in four-space and two singularities (a Big Bang and a Big Crunch). The time it takes a light ray to circumnavigate the hypersphere is equal to the total time the Universe exists for, so these two spacecraft would never meet.
)
also
(Yes, that is one possibility, which implies that it will also end in a Big Crunch. It is temporally infinite if and only if it is spatially infinite.)

that original point is the third system i was talking of, i worded it unnecessarily complicated.
i'm not sure on robo's second point
Title: Re: relativity.
Post by: optimisticcynic on July 25, 2009, 03:07:55 PM
ahh, now i get it. i'll think about that

edit: i checked with some literature and as far as i understood it it is not possible for any object to determine it's movement compared to an absolute space. the reason lies in the symmetry of physical laws concerning transformation in another system.

I know that in a normal infinite universe that it should be impossible I am trying to get around that and wondering if it would work
I don't know a lot about it. I spend a lot of time reading about it but I took Calc IV this year. in other words most of the equations are beyond me.
I am confused why you say though if you leave out a third system they would come up with the same time.
forget that part about leaving out the third system, that was typing without thinking  :P
Quote
Oh one last thing, I sent this same question to robosteve and he said something that I can not confirm or disprove.
quote(
Also, this scenario cannot occur. They do not meet "on the other side" of the Universe - in order to define what "the other side" is, you need a reference point which would need to be one of the machines involved, and in order for one to meet the other it would need to return to this original point. This means that in order for one spacecraft to come back to meet the other, it needs to circumnavigate the entire hypersphere, which is prohibited by relativity because (if I remember correctly, and hopefully somebody who knows more about relativity can verify or refute this) a hyperspherical Universe is a black hole with a Schwarzchild radius in four-space and two singularities (a Big Bang and a Big Crunch). The time it takes a light ray to circumnavigate the hypersphere is equal to the total time the Universe exists for, so these two spacecraft would never meet.
)
also
(Yes, that is one possibility, which implies that it will also end in a Big Crunch. It is temporally infinite if and only if it is spatially infinite.)

that original point is the third system i was talking of, i worded it unnecessarily complicated.
i'm not sure on robo's second point
So do you agree with robo's first reason on why my idea would not work?
Title: Re: relativity.
Post by: iznih on July 25, 2009, 04:58:06 PM
yes, i think he's correct on that.
Title: Re: relativity.
Post by: Ski on July 25, 2009, 09:00:57 PM
How long until Robosteve is unbanned?

Depends on your frame of reference.
Title: Re: relativity.
Post by: optimisticcynic on July 25, 2009, 09:47:03 PM
yes, i think he's correct on that.
but wouldn't robosteves reasoning only work if there is a big crunch at the end of the universe?
I thought it appeared there was not going to be a big crunch? I mean I am not arguing that you are wrong. I just would like evidence that as robosteve put it
(Yes, that is one possibility, which implies that it will also end in a Big Crunch. It is temporally infinite if and only if it is spatially infinite.)
Because if there is no end to time but space is definite then it seems like it could still work.
Title: Re: relativity.
Post by: iznih on July 26, 2009, 03:28:33 AM
yes, i think he's correct on that.
but wouldn't robosteves reasoning only work if there is a big crunch at the end of the universe?
are you referring to his second point? the setting of a meeting point would not necessarily require a big crunch.
i think the fact that you need the meeting point itself destroys the experiment. if that meeting point was moving exactly the same things would happen as if it was absolute stationary. so in order to know which machine was moving absolutely faster you would need to know that certain stationary frame of reference in first place.
Title: Re: relativity.
Post by: optimisticcynic on July 26, 2009, 02:01:16 PM
yes, i think he's correct on that.
but wouldn't robosteves reasoning only work if there is a big crunch at the end of the universe?
are you referring to his second point? the setting of a meeting point would not necessarily require a big crunch.
i think the fact that you need the meeting point itself destroys the experiment. if that meeting point was moving exactly the same things would happen as if it was absolute stationary. so in order to know which machine was moving absolutely faster you would need to know that certain stationary frame of reference in first place.
I thought that it would not allow you to know what the zero speed for the universe is, however wouldn't it at least allow you to know which one is going faster. not necessarily how much faster then the absolute zero but which one is going faster. I can not see why you couldn't just look at the times when they meet since normally acceleration is what allows you to let everything be relative and there was no acceleration in this system.