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RandomThoughts Donating Member (1000+ posts) Send PM | Profile | Ignore Mon Dec-20-10 09:44 PM
Original message
Watching show on Einstein.
Edited on Mon Dec-20-10 09:48 PM by RandomThoughts
Something that does not make sense about time dilation.

I posted this before briefly, but since Einstein show is on TV, figured would post it again.


Here's the thing, the people that flew to the moon confirmed time dilation occurs when there clock was a bit off of time on earth. So there is dilation.


As you move faster through space you move slower in time. Pretty simple.

So if you stand on earth, and someone flys away from you really fast they move slower in time. But that assumes that the earth is stationary 0 speed, what if the earth is actually moving really fast, and the object moving away is moving slower not faster.


Basically there are two object, there speed relative to each other can be deduced, but not there actual speed, since each would think the other is moving away quickly. There must be a 0 speed in the universe. And if there is, then the earth is above that rate at some point. and the rocket moving in one direction would be even higher above that, but in the opposite direction it would be moving slower then it.



If the earth is moving .5 speed of light -> that way. And an object moves towards it at <-.25 speed of light, then time dilation would be backwards, since the earth would be moving faster and then slower in time. While if the object moved away from earth, then it would be moving .75 speed of light, and then you would see expected time dilation.


So here is the question, why did time dilation happen on the trip to the moon, and then it was not canceled out on the return trip.


Best guess is it has to do with trajectory, but if that is so, then exact 0 speed could be determined. Or slamming two atoms from different directions should be able to show different time dilation dependent on direction based on time of day, and day of year.

So the time dilation shown in particle acceleration should show different effects based on what side of sun the earth is on.



however that brings up speed as a fact of direction also for dilation effects. because the object being measured against, is also in motion.


So someone should be able to figure the exact speed through space that the earth is moving, and the direction from that 0 speed



So wouldn't that make time dilation not relative to some other object, but relative to some speed 0 somewhere in space.

Making it not relative, but fixed to some cosmic 0 speed.



How could the rocket flying to the moon be said to be moving faster in space time while going both directions, unless you state that the speed of the rocket was actually more then the speed of earth when moving through space. In other words, the earths speed, moving around the sun, moving in the galaxy, moving around the universe in a galaxy, has to be less then the speed of a rocket going to the moon. Or the dilation could not be computed unless Earth speed was known. It could be that trajectory explained it. But anyone that said they could calculate based on speed of a rocket, would not make sense, since they would have to know where 0 speed is.



And that is a pretty strong case that the Earth is actually, really, truly, the center of the universe. So either the clock moving to the moon has to be shown to be slower in one direction, faster in the other, or earth is closer to 0 speed then the speed of a rocket.


Making the entire argument for big bang pretty skeptical, and making it more likely that the entire universe was created around the earth, if it is that close to 0 speed.


So question of the Earth as center of Universe might be able to be proven, using time dilation effects in multiple directions going away and towards earth.


And if the Earth is center of Universe, based on laws of speed through space, what would that mean. Furthermore, there could be a location on the earth that is that exact 0 speed. Making it more interesting.


Was going to write a short story on that idea, but anyways can anyone explain that inconsistency in time dilation?







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Vinnie From Indy Donating Member (1000+ posts) Send PM | Profile | Ignore Mon Dec-20-10 09:54 PM
Response to Original message
1. Meh! It's all relative.
Cheers!
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laconicsax Donating Member (1000+ posts) Send PM | Profile | Ignore Mon Dec-20-10 10:26 PM
Response to Original message
2. The simplest explanation is that you don't understand time dilation.
The measurements of time dilation that are confusing you are taken relative to the Earth. That isn't assuming the Earth as the center of the Universe or as a stationary point, but just using the rate at which time passes on its surface as a reference point. Any point in the Universe can be used as a reference point, and the Earth is very convenient for us.

Saying that "if you stand on earth, and someone flys away from you really fast they move slower in time" is accurate only in your frame of reference. If someone flies past you really fast, you are moving faster in time relative to their frame of reference.

The Earth is not and has never been the center of the Universe.
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RandomThoughts Donating Member (1000+ posts) Send PM | Profile | Ignore Mon Dec-20-10 10:55 PM
Response to Reply #2
4. You miss the point I was making.
If two objects are in space, and one is moving faster, then both will see the other as moving faster. If it is relative.

use two space ships. Each would see the other ship as the one 'moving fast' so why would one of them move slower in time then the other, unless there is some absolute 0 speed.


If a ship is moving close to the speed of light, when it looks at you, it would see you moving at close to the speed of light. unless there is some benchmark 0 speed somewhere. And that bench mark (since not being light) is the speed of time passage.


So you can determine who is actually moving faster by dilation effect, from that then you can find an actual 0 speed point somewhere in the universe.


weather the earth is at 0 speed or not is not really the point, the story of the clocks on the ship to the moon has holes in it.



Tell me how do you know who is moving faster between the two objects. You need a point of reference, how do you not know if the earth flew by the rocket ship and the rocket ship was stationary. Your only way to know is time dilation, since speed of light is constant.

I actually think I understand it, however it could be actually acceleration, where space time also moves, and only applications of force could cause dilation, but that still would break some of those concepts.


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laconicsax Donating Member (1000+ posts) Send PM | Profile | Ignore Tue Dec-21-10 01:06 AM
Response to Reply #4
7. The point you're making is based on a misunderstanding of relativity.
Edited on Tue Dec-21-10 01:07 AM by laconicsax
Each would see the other ship as the one 'moving fast' so why would one of them move slower in time then the other, unless there is some absolute 0 speed.
Because the rate at which time passes is proportional to speed. You don't need some absolute 0 speed to see that someone's clock is running slower or faster.

tell me how do you know who is moving faster between the two objects.
If two objects are in space, and one is moving faster, you can determine which is moving faster by using time dilation--the faster ship will record a slower passage of time.

You need a point of reference, how do you not know if the earth flew by the rocket ship and the rocket ship was stationary.
There are no privileged reference points; it's all relative. To an observer in the rocket ship, the Earth did fly by the ship, which remained stationary. Think about that the next time you're in a moving car.

the story of the clocks on the ship to the moon has holes in it.
Sorry, it doesn't. Less time elapsed for the Apollo astronauts during their mission than for the mission controllers on Earth.

I actually think I understand it, however it could be actually acceleration, where space time also moves, and only applications of force could cause dilation, but that still would break some of those concepts.
Acceleration does play a factor, that is, the acceleration due to gravity. Time passes 4x10-16 faster for an object at one foot above sea level than for an object at sea level because of how gravity warps space-time.

Try this site. I haven't spent much time there, but it looks like it might be a good primer on relativity.
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RandomThoughts Donating Member (1000+ posts) Send PM | Profile | Ignore Tue Dec-21-10 02:46 AM
Response to Reply #7
10. When this dawns on you yuor going to get it I think.
Edited on Tue Dec-21-10 02:53 AM by RandomThoughts
If two objects are in space, and one is moving faster, you can determine which is moving faster by using time dilation--the faster ship will record a slower passage of time.

Thats what I am saying, you only know which is moving faster by time dilation.


Object1 -> .9 of light speed. object 2 <- .1 speed of light.

for the first object to still see light at the speed of light, it has to move slower in time. However object 2 can view the object and see it moving at .9 and view it moving slower in time.

but how do you know that the 2nd object is not really moving faster if it is only relative to each others speed.


any two objects moving, there is no way to know 'which is moving faster' without a third reference


You have object1 object2, you can see which is moving faster by time dialation, but the fact that one of them is moving faster means there must be a minimum 0 speed somewhere. Instead of speeding up the object1 item, slow down the object2 item. and you would still see a time dilation larger between them. There has to be some limit of 'slow down' that the object 2 can reach.


at some point the slow down of object two would be a speed up after it reaches speed 0, basically again moving but in the other direction. However that would not be based on directional or vector velocity, and it can not be based on vector velocity, since an object moving towards or away would have the same time dilation effect by a viewer.

So, with object1 moving away then back from object2. The speed of object1 - object2 would have to be less then speed object2 - speed0.


This actually makes sense. there has to be a base speed to know which item is actually moving slower. and the Earth, in a galaxy is moving, so if a ship moved away then back, the away might be moving faster, but the speed returning back would be slower then the speed of the earth.

Basically when the rocket returns from the moon, in the example, it could be not moving at all, and the move of the earth, around the sun, or as the galaxies move, would be actually approaching the rocket.

If that is not the case, then the earth is real close to speed0, or moving at a rate slower then a rocket speed compared to speed0



So in any direction, two moving objects have a time dilation that is an effect of the difference in each other speed, but at some point one of the ships could slow down to a minimum speed of space 0 speed. after that it would, while continuing to move in the same direction again start to speed up.

So there has to be a 0 speed somewhere. I don't know the speed of the rotation of galaxies, but if they are also moving through the universe, then one side could be moving slower then the opposite side, and opposite sides of a galaxy would be in different dilation effect.

If you throw a Frisbee, and it spins, relative to the ground, one side goes faster the other side slower, even though both sides spin at the same rate.

I understand it is what each 'moving object' sees of the other, but because there is a time dilation effect, then there has to be a point where object2 can not go any slower. That point would be space speed 0.

I was curious why nobody found what space speed 0 was because it could actually be really fast. And in that case, a rocket leaving earth would dilate slower while traveling away, and then earth would dilate slower on its return trip.

Or earth is not moving, and is the center of Universe. Or moving slower then rocket speed for there not to be a up and down effect on away and return of a rocket flying away.


The point is they could not have calculated time dilation on trip to moon just from difference in speed between earth and rocket, since the rocket could be moving slower when moving the opposite direction.



When I said acceleration, I was thinking of possibilities of an inertial factor in space, where it is change in speed that causes it within some controllable area by some factor. Just trying to resolve the contradiction. Earth could be at space 0 if many places were at space 0 by the fabric that determines the speed of light is changeable or different, acceleration was not the correct word, was just trying to find an explanation for the discrepancy. basically if earth was near space 0, there could be an environmental effect like objects of mass that move space time with them in a way to create the 'space0' speed. Just a thought on possible many speed 0 areas by movable space. then Dark energy would be creation of space time in low grave areas to fill in difference of pressure, but that gets way out there. and only trying to resolve the need for a 0 speed to be able to say two things are differential in speed with one object moving faster the other slower.

If speed 0 was far enough away from our current speed, you could even get into some interesting postulations of dilation effects as you approach speed 0, that was story idea. basically an ironic twist where character gets speeded up by approaching speed 0, but that part is fiction.




If there is no speed 0, and two objects are moving, then what happens when one of the object slows down, how slow can it go? At some point it will again start going faster in the other direction. showing that time dilation has three factors, speed of two objects and some speed0 factor.

Two objects both moving .5 away from any point in any direction, would have same 'time' no dilation effect. But you could not know which is moving and which is stationary without a speed0 It is not just relative between two objects but also relative to a third object, speed 0

There has to be a speed 0.

Or space time moves also, or earth is real close to speed 0, at least as close as speed of a rocket, or nobody computed dilation of clock on rocket, and a tangent allowed it to occur.



Out there idea.
I posted this same thing years ago, not anything new, but it could possible explain some expansions that appear to be created by a force, when they could be creation or flow of space time into areas spread apart by moving speed0 areas. but that is out there.
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laconicsax Donating Member (1000+ posts) Send PM | Profile | Ignore Tue Dec-21-10 01:32 PM
Response to Reply #10
12. There's nothing for me to get. Your questions are based on a misunderstanding.
You don't need a "speed 0" and there really isn't a "speed 0" because everything is moving relative to something else. Everything is stationary in its own inertial frame of reference and moving in another.

To simplify this concept, imagine you're on an airplane with video camera.

While in flight, you toss the camera up an catch it when it falls.
From your frame of reference, you were stationary and the camera traveled away from you and back in a straight line.
From an observer on the ground, the camera followed a curved trajectory while you traveled in a straight line.
From the camera's perspective, it was stationary while the plane and everyone on it accelerated downwards and then upwards again before coming to rest.

Which is right? They all are.
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RandomThoughts Donating Member (1000+ posts) Send PM | Profile | Ignore Tue Dec-21-10 02:09 PM
Response to Reply #12
13. LOL, you still don't get it.
Edited on Tue Dec-21-10 02:13 PM by RandomThoughts
If all speed is relative to every other speed, then how can you say one ship is moving faster, and the other slower. And if you can not say one ship is slower and the other faster, then why is there a dilation effect in opposite directions when viewing each others. If it really was relative for both objects then their would be no time dilation, since both would see the other slow, or both would see the other speed as faster, making neither do dilate, or dilate the same way. Time dilation proves a third point of reference is required.


Two ships moving at each other, with a closing rate near speed of light. Which one is moving faster.

You need a third point of reference to exist to say that.


Two ships moving same direction moving near speed of light. They would not see dilation becuase they are at same speed. However two ships moving away from each other, or at each other could have no time dilation seen if they were same distance from speed0, since dilation effects are not vectors, and do not matter if objects are aproaching each other or moving away.

And if the speed is not vector orientated then there must be a third point of reference. There has to be speed0.



However it is possible that space time moves with many objects, and expanse of universe is creation of space time in some areas between moving space0 parts, so the galaxies and even solar systems do not have to be in motion relative to each other, and it could be that space time is created between them without actual motion through space, allowing for speed0 in many places.

Then that could explain speed0 in many places that have Doppler shifts an illusion of movement.


Eventually the equation could explain 'time existing' since theoretically speed0 could be infinate passage of time, and light speed, no passage of time. Although that is more of a story idea, and Earth being close to speed0 would make that probably unlikely, hence why I wonder what speed 0 is.


Also if you are in a 'space ship' moving fast, and inside that space ship you have a circular object shooting particles in every direction and looking at there time dilation, then you could know you actual speed relative to other objects, outside of dilation effects, allowing for computing travel. Since in sublight travel dilation is only way to know your speed, so a contained object with particles fired and looked at going in many directions, effectively allows for a speedometer on a space ship without viewing an external object.




You say I don't understand because you are not thinking about what I am posting.




While in flight, you toss the camera up an catch it when it falls.
From your frame of reference, you were stationary and the camera traveled away from you and back in a straight line.
From the camera's perspective, it was stationary while the plane and everyone on it accelerated downwards and then upwards again before coming to rest.


So if the camera sees the person moving, and the person sees the camera moving, why do they have dilation effects in different directions. One of them is moving faster for it to dilate differently, and for one of them to move faster, there has to be a third point of reference.


If you say the third point is 'the speed of light' then by simple observation of an object slowing, you show there is also a speed0, since once a external point of reference is required in relativity, then speed0 must exist for light speed to exist. As shown by slowing a ship to increase dilation difference
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laconicsax Donating Member (1000+ posts) Send PM | Profile | Ignore Tue Dec-21-10 08:35 PM
Response to Reply #13
15. Seriously. Go to the library, find a book that covers relativity, read it.
There's so much wrong with what you just wrote that I don't know where to start.
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RandomThoughts Donating Member (1000+ posts) Send PM | Profile | Ignore Thu Dec-23-10 04:53 AM
Response to Reply #15
16. LOL.
Just answer this one question.

If two objects are moving, one is moving faster, the other stationary. If there movement is relative, then why would one move slower in time when observed by the other, and one move faster in time.

The classic example is that time moves slower as someone moves faster. How do you know which one is moving faster.


You can't answer that without a frame of reference.


Two ships are moving apart at .9 speed of light, not going to tell you which one is moving fast, and which one is moving slow. So how would know which one would move slower in time.


You can't without also knowing something about space they are in, to determine which one is actually moving.

Space itself is part of figuring 'speed' of an object, so you should be able to find speed0 space.



I agree I added conjecture from story ideas, but the basic concept is sound. How do you know which one is moving faster.


Can you think of that. Two ships moving apart, you can't even tell which one is moving or stationary, but then you find time dilation, and if time dilation exist, from that you can compute which one is moving faster, and if you can do that, you can compute some minimum speed or speed0




On a side note, in a famous Spielberg movie, a girl said 'their here'. I think that is another reference to this song, as are many other usage of lines in films from that song.

Send in the clowns.
http://www.youtube.com/watch?v=5os4NFeKFFs


And if you read a book to understand it, are you sure you understand it? Or do you understand the books perspective. Is my post moving or is yours?





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Jim__ Donating Member (1000+ posts) Send PM | Profile | Ignore Thu Dec-23-10 10:21 AM
Response to Reply #16
17. "... why would one move slower in time when observed by the other, and one move faster in time."
If A is in motion relative to B; then the movement of A relative to B is symmetric to the movement of B relative to A. The answer to your question is that from A's point of view, any clock being carried by B, slows down. And, from B's point of view, any clock carried by A, slows down the same amount.

The object of this exercise is to show explicitly how it is possible for two observers in inertial frames moving relative to each other at a relativistic speed to each see the others clocks as running slow and as being unsynchronized, and yet if they both look at the same clock at the same time from the same place (which may be far from the clock), they will agree on what time it shows!

Suppose that in Jacks frame we have two synchronized clocks C1 and C2 set 18 x 108 meters apart (thats about a million miles, or 6 light-seconds). Jills spaceship, carrying a clock C', is traveling at 0.6c, that is 1.8 x 108 meters per second, parallel to the line C1C2, passing close by each clock.

more ...
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RandomThoughts Donating Member (1000+ posts) Send PM | Profile | Ignore Thu Dec-23-10 01:21 PM
Response to Reply #17
18. So if each person sees the other clock slow down.
Edited on Thu Dec-23-10 01:23 PM by RandomThoughts
Then they are in the same time reference.

And most shows on relativity say that the faster moving person would see the stationary person as moving faster in time.

I have Read Einstein's dreams, a book on his formulations of some of those thoughts, and they state that people moving different speeds move in different time frames, and it is simple to understand that moving faster if light speed does not change, then time must change. However if every moving object sees other moving objects as the moving faster and moving slower in time, then everything is in the same 'time frame'


If they both see the other moving slower in time, then no time dilation occurs regardless of who is moving faster. Because the moon rocket clocks would have slowed down when viewed from earth, and the earth clocks would have slowed down when viewed from the rocket. And if both the faster moving object slows down the same as the stationary, then there would be no time dilation recorded on the moon rocket clocks.



And the shows I have seen that describe dilation show that viewer of the slower moving object as moving faster in time, not what is stated in your post.

So if that post is correct, then the shows on time dilation are incorrect, and they are shows used to teach the concept in schools, since I saw it there, and saw a similar show on a physics show on TV.

If A is in motion relative to B; then the movement of A relative to B is symmetric to the movement of B relative to A. The answer to your question is that from A's point of view, any clock being carried by B, slows down. And, from B's point of view, any clock carried by A, slows down the same amount.

Then there is no change in any clock, since relative to any other object, they all are moving the same speed, if there is not a third point of reference.
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Jim__ Donating Member (1000+ posts) Send PM | Profile | Ignore Thu Dec-23-10 03:16 PM
Response to Reply #18
19. No, they're not in the same time reference.
Edited on Thu Dec-23-10 03:17 PM by Jim__
Did you read the example that I posted, here. It walks you through the scenario that you're describing. It works it out in detail.

My comment:

If A is in motion relative to B; then the movement of A relative to B is symmetric to the movement of B relative to A. The answer to your question is that from A's point of view, any clock being carried by B, slows down. And, from B's point of view, any clock carried by A, slows down the same amount.


And your comment on my comment:

Then there is no change in any clock, since relative to any other object, they all are moving the same speed, if there is not a third point of reference.


Your comment is essentially ignoring most of what I said. I don't know if you're being serious, or just kidding.

The answer to your question is that from A's point of view, any clock being carried by B, slows down.

That explicitly states that, from A's perspective: any clock being carried by B, slows down. So, from A's perspective, clocks in B's reference frame are running slower that clocks in A's reference frame. Sure, by symmetry, B has the symmetric experience, namely, it sees clocks in A's time reference as running slow, slower than clocks in its own reference frame. So, yes, there are changes in the clocks; it's just that the changes depend upon your reference.

Because the moon rocket clocks would have slowed down when viewed from earth, and the earth clocks would have slowed down when viewed from the rocket. And if both the faster moving object slows down the same as the stationary, then there would be no time dilation recorded on the moon rocket clocks.


Do you know when they verified the difference in the clocks? While the rocket was in flight? Or, a difference in time after the rocket returned to earth? If, the earth station asked the astronauts what their clock showed and compared it to the earth clock while they were in flight, then they would see time dilation - this explicit case is diagrammed on the reference that I gave you in post 17. If they compared the clocks after the rocket had returned to earth, then, you have to take gravitational time dilation into account (I noted in post 14 that their are 2 components to time dilation). If you want to read the NASA paper on time dilation on the flight to the moon, you'll notice that they are taking gravitational effects into account.

So if that post is correct, then the shows on time dilation are incorrect, and they are shows used to teach the concept in schools, since I saw it there, and saw a similar show on a physics show on TV.


The website that I referred you to in post 17 is a page that belongs to a physics professor at the University of Virginia, Michael Fowler. That post is based on one of his lectures. That post supports what I am saying. So, your claim that it disagrees with what is taught in "schools" is not correct.

If you want to know how relative motion effects clocks relativistically, read the reference from post #17 (same reference given at the beginning of this post). Based on your post #18, you never read that reference. If you disagree with something in that example in the reference, please state what it is that you disagree with.

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RandomThoughts Donating Member (1000+ posts) Send PM | Profile | Ignore Thu Dec-23-10 07:10 PM
Response to Reply #19
21. There is a statement.
Thus if both Jack and Jill are at C2 as Jill and her clock C' pass C2 , both will agree that the clocks look like: <-- that is what I don't agree with.



I am saying that Jill 8 jack2 10
may be Jill 10 jack2 8


If Jack1 and Jack2 are actually the items moving, and Jill was stationary. You added a third point, but did not answer how you know if Jill is moving, or Jack1 and Jack2 is moving.

How do you know Jill was moving .6speed of light, maybe she was stationary, and jack planets were moving.


There must be a 'speed' reference outside the objects still. How do you know which one is moving and which one is stationary. You have to use the reference of the dilation, from the 8 10 to know that.

So you don't know which is moving and which is stationary until you know which dilates. And if that is how you determine it, how do you know if the presumed stationary objects are not also in motion. And if you say it does not matter, then how can you say both agree on one clock being at 8 seconds, the other at 10.

And if you say that both in motion does not matter, because it is relative, then what happens if you slow them down till they reach 0 speed, and then after that one starts speeding up the other direction.

The stationary jack planets are presumed to be at 0. If they started at .1 then you could do the same calculations, at 0 you could also, but once they go back up to .1 in the other direction your calculation would change.

without doing the math, if .7 and .1 (excluding exponential effect for simplicity)
That would be the same as .6 and 0. (since relative speed is the same)
but it would not be the same as .5 and .1 in the other direction.

So your calculations would show 8, 10
8, 10
then something like 9 10 on the clocks as the stationary planets go back to motion in other direction. Since 'speed' is non vectoral in calculation. Unless you are saying it includes a vectoral component, where the only speed is the difference in speed between two different objects.

And if it includes a vectoral component, they did not look at the clocks when they returned from the moon and know the time they should say, unless they calculated all the vectors of speed differences between different directions. although a computation while in a strait vector away could fit into that, it would make the reports on a few shows of that case inaccurate. And it also does not answer why on science films, it shows one person seeing the other actually moving faster in time, was that science show incorrect, by your computations it shows that show wrong, making the developers of TV shows on science wrong. what you are saying is that a show on relativity does not mach your comment that each sees the other moving slower.


Or are you saying that there is a vector component when deducing the 'speed of one object' and if that is the case then time dilation would be dependent on direction, which makes even less sense. Since a set of two object moving parallel and perpendicular at same speeds would have different time dilation, even if moving same fraction of light speed.

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Jim__ Donating Member (1000+ posts) Send PM | Profile | Ignore Fri Dec-24-10 06:08 AM
Response to Reply #21
22. Read the problem statement: "Suppose that in Jacks frame we have two synchronized clocks ...
C1 and C2 set 18 x 10**8 meters apart ..."

And, once again, the description from post #17:

If A is in motion relative to B; then the movement of A relative to B is symmetric to the movement of B relative to A. The answer to your question is that from A's point of view, any clock being carried by B, slows down. And, from B's point of view, any clock carried by A, slows down the same amount.


So, when you claim:

I am saying that Jill 8 jack2 10
may be Jill 10 jack2 8


You're ignoring the reference frame of the stationary clocks. To get the result you want, you have to put the stationary clocks within Jill's reference frame. This is difficult given that Jill's reference frame is a rocket. But, as a thought experiment, picure a rocket that is 18 * 10**8 meters long and put clocks at each end of the rocket. Using those clocks as as the new c1 and c2, and a different clock in Jack's reference frame, you can get the result of c2 being at 10 and Jack's clock at 8.

You have to be aware of the different reference frames.
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RandomThoughts Donating Member (1000+ posts) Send PM | Profile | Ignore Sat Dec-25-10 02:45 AM
Response to Reply #22
24. You are saying the clocks are stationary.
How do you know that.

That is an assumption, what if the rocket is stationary and the clocks are moving. The only way you can say 'stationary' is to add an element outside of the objects in motion. Or to assume some speed0. And that means it is not relative only to the objects.


When you say stationary clock, you make my case for a speed0 in the equation.



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Jim__ Donating Member (1000+ posts) Send PM | Profile | Ignore Sat Dec-25-10 05:56 AM
Response to Reply #24
25. Yes, they're stationary within a reference frame.
If they're not stationary within that reference frame, then they're in relative motion with respect to that reference frame - i.e. they're in a different reference frame.
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RandomThoughts Donating Member (1000+ posts) Send PM | Profile | Ignore Sat Dec-25-10 10:00 PM
Response to Reply #25
27. Here is the basic thing.
Edited on Sat Dec-25-10 10:35 PM by RandomThoughts
If the reference frame is any two objects, then you have issues of vector, since relative speeds also consist of direction. If they do not consist of direction, then you have the issue of one slowing down till reaching speed0 then speeding up again in the other direction.

if you state 'any reference frame' making actual speed0 or lightspeed irrelevant, then you state that neither speed0 or light speed can ever be reached.

And for speed0 not to be able to be reached it must exist.


Do you say it is vector based, where the differential in speed is only the difference between two objects.
If it is only relative between traveling objects, then it is easy to show many examples that does not work for.




Three moving objects approaching a meeting point, they all move same speed, all their clocks when checked after meeting would have the same time of travel.

The second example, without any external reference is the exact same image as the first, however their clocks would not say the same, since they are not only moving at different speeds, they are traveling different distances. For a time reference to not have any external reference point, then extrapolations would have to be perfectly linear as one approaches the speed of light, but it is exponential.



If you say that there is no 'external reference' besides the objects in question, then you have to say that those two cases are the same. since they are the same without some base comparable speed for all of them.


Here is the thing, seeing someone moving slower or faster is not really relevant, since it is not a permanent state still viewable at point of meeting, however a dilation effect can be viewed post journey, so it must be able to be consistent across many examples since it sets a recordable record of an effect. Mass increase for example is not relative at point of meeting, since with an immediate stop effect, measure would show mass the same as beginning of flight, however time dilation exist after the travel event in that example. For it to continue to exist as a record, it has to be consistent in all cases. That can only be done with the same 'reference frame' for everything, or one single time frame, that time frame is usually light speed, but if that time frame exist then speed0 must exist.

Side note, I do not postulate that light speed can not be reached, nor speed0, just that they must exist.


The same conversation can also be made on topic of moral equivalency, some say that what is truth is only the measure between two positions, making many disingenuous discussions. I state that there is a moral context everything is contained in, and truth or perspective is not just relative to the views of two people, even if while in a normal state they have not reached light speed yet.

And also why I like the relationship of, going faster, as a metaphor, although being a metaphor, lightspeed and speed0 are part of label trap, so could be flipped and would still fit metaphor. Not trying to set a label trap there.
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Jim__ Donating Member (1000+ posts) Send PM | Profile | Ignore Sun Dec-26-10 11:34 AM
Response to Reply #27
28. I'm not sure how to interpret your diagrams.
Are the vectors showing the direction of travel? If not, can you specify what those directions are?
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RandomThoughts Donating Member (1000+ posts) Send PM | Profile | Ignore Sun Dec-26-10 01:08 PM
Response to Reply #28
29. The direction would not matter, if it did it creates inconsistencies.
It seems you think the only thing that matters is the speed of a ship compared to some other ship, including direction.

If you do not have a universal point of reference, then those two diagrams are exactly the same. However the record of dilation would be different.


Because the 'record of dilation' can be seen by any object at any future point, all objects must be in the same frame of reference, removing the possibility that dilation is only relative to two objects in motion.


Everything is compared to some base speed, not each others motion. Even if from any location your own view of motion changes what you see in some other object, it is still recordable by its dilation as actually comparable to some universal frame of reference.

Time dilation must include the 'some universal speed' in the calculation. Although there are ways to see space as many floating objects at same speed, even when giving indication of motion by creation of spacetime between them. Still all relative calculations need a universal point of reference in the calculation.

The way to explain the diagram, is the first one is viewing from a stationary point while the second one is viewed by an object moving the same direction as green line at speed x covering a distance y. The point is any observation adds another point. Then you have to draw the graph with that extra point in the equation, then another point views it, and you have to include that point, then you have to add that point, and another viewing point. etc... till every point is in the equation, making it no longer relative. Since any point at some time could view the effects of time dilation of some other point, they must all be in same time reference.

Are you being disingenuous in your argument? saying that 'direction' matters makes the ability for time dilation effects to be stored and compared at some point impossible, since objects moving same speed but different directions would have different dilation dependent on who they compare to, but all those dilation could be recorded on a clock.


Not math related thought, on the metaphor of two directions to move in life, faster or slower.
(side note on metaphor, in that metaphor the speed is the direction, so saying direction does not matter is not saying the direction you go does not matter, since in that metaphor the speed you move denotes the direction you are facing, without label trap of coarse.)

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Jim__ Donating Member (1000+ posts) Send PM | Profile | Ignore Mon Dec-27-10 02:56 PM
Response to Reply #29
32. Let's look at your diagram from post #27 then.
Let there be an object of the same color as the vector at the tail of the vector. Let the point of convergence of the blue object (b) and the green object (g) be an inertial reference frame. Let their constant speed be 0.6c According to the frame at the point of convergence, how fast is b approaching the point? How fast is g approaching the point? Then, let there be an inertial reference frame at b. How fast is g approaching it? Who has the correct measure of time?

Does direction matter? Let's reverse the direction of b's motion but keep the rate at 0.6c. How fast is b moving relative to g? What caused the difference between the 2 speeds? Is there time dilation between b and g?

Still all relative calculations need a universal point of reference in the calculation.

In the books and articles that I've read on special relativity, I've never seen any mention of a universal point of reference (the universal that I've seen is the speed of light). Do you have any reference that supports your claim? Do you have any argument to support your claim? I don't mean some proclamation, but a reasoned argument that supports it. Here's an excerpt frome wiki stating that there is no absolute state of rest:

... Einstein's solution was to discard the notion of an aether and an absolute state of rest. Special relativity is formulated so as to not assume that any particular frame of reference is special; rather, in relativity, any reference frame moving with uniform motion will observe the same laws of physics. In particular, the speed of light in a vacuum is always measured to be c, even when measured by multiple systems that are moving at different (but constant) velocities.


Without either a reference or an argument to support your claim, there is no point in continuing to discuss it. Your opinion seems to differ from everthing I've ever read on relativity. I'd like to see something that supports your opinion.

Special relativity does have an invariance of the laws of physics across inertial frames. That may be the measure that you're looking for.
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qazplm Donating Member (1000+ posts) Send PM | Profile | Ignore Mon Dec-27-10 01:34 PM
Response to Reply #24
30. there is almost nothing in the universe that
is "stationary" almost everything if not everything moves at least a little bit whether it is sitting on a moving body like a "stationary" clock on the Earth's surface, or it is an object in space that is "stationary" at say a LaGrange point but still moving.

Gravity is always tugging and pulling at everything to some degree.

The bottom line is this.

Einstein showed and our GPS and clock experiments confirm (among a lot of other experiments) that moving faster equals time slowing down and moving slower equals time speeding up. Similarly, gravity wells change time the deeper you go into them. Obviously, if you truly had no motion (and no gravity well at all, which is hard to imagine existing anywhere in the universe) then you'd have no impact of speed or gravity on time and one could possibly say you have an absolute value for the passage of time, maybe, although probably not.

But that's not particularly important in any meaningful way I can see, and it's hard to understand what your issue is with relativity because it is hard to decipher your posts.
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laconicsax Donating Member (1000+ posts) Send PM | Profile | Ignore Thu Dec-23-10 07:01 PM
Response to Reply #16
20. Reading books is one way to learn about a subject. I suggest you try it.
Your question demonstrates quite well that you don't understand relativity as it pertains to time dilation. Please do yourself a favor and take some time to learn about the subject. There are several texts which I could recommend, all of which are probably superior to the TV program which forms the basis of your knowledge.

Also try typing in complete sentences. You may find it a more effective method of conveying your thoughts.
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TheMadMonk Donating Member (1000+ posts) Send PM | Profile | Ignore Tue Dec-21-10 02:10 AM
Response to Reply #4
9. Vectors cancel over time.
Essentially for the two to make comparisons they have to come close enough together at some time to exchange information. And by the time all the manouevering is done, all the pluses and minuses cancel in just the right way for any information they exchange to make sense.

Starting from the same point, and making mirror image journeys, to travellers would come back together to find their watches in agreement. And no matter how they travel, at any point where they are able to exchange information, each will get their own "right" result. As will any third parties making their own observations.

Read Hawking's "A Brief history of time." He explains this apparent paradox quite well.
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MrsBrady Donating Member (1000+ posts) Send PM | Profile | Ignore Mon Dec-20-10 10:38 PM
Response to Original message
3. i took 2 college astronomy classes last year...
but I'm no expert. However, I did do my homework.

It's hard to conceptualize in a way. And I'm no good with the math. I can only do the math with someone walking me through it.
I get the theory, mostly. Don't ask me to do the math.

But I think it has something to do with the fact that
the earth has it's own time,
the moon has it's own time
the rocket would have it's own time as well
...they probably didn't take the same route back that they took there....
they were also on the moon for a while.
I think that would do it?

I wouldn't think that it was an enormous time difference.
My guess would be a few minutes at the most, maybe a few seconds. I don't know. Can't be that much.

Mass affects the time...if a clock is closer to the larger the mass, the slower the time...and vice versa smaller mass/faster time


And no, the earth is not the center of the universe, as the sun and planets formed in kind of a centrifuge fashion...with the heavier stuff at the middle, and gasses and junk toward the outside. I'm oversimplifying that, but they are finding this to be true, more or less, in other planetary systems as well. The earth does go around the sun...or rather the sun and the earth rotate around a central point, which I think is probably pretty close to the sun because of the larger mass of the sun.

anyway...i think that's right.
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RandomThoughts Donating Member (1000+ posts) Send PM | Profile | Ignore Mon Dec-20-10 11:01 PM
Response to Reply #3
5. My arguement is not that the earth is the center.
Edited on Mon Dec-20-10 11:02 PM by RandomThoughts
However if they say they can calculate dilation on trip to moon, without trajectory then they would need to know 0 speed.

...they probably didn't take the same route back that they took there....
they were also on the moon for a while.
I think that would do it?

Thats trajectory comment.




My point is this, if time dilation happens the same amount for every object leaving earth in every direction, then it could be said that the earth was moving 0 speed.

So you should be able to find 0 space speed.

You should even be able to find differences in dilation based on circular path of planet around sun. Since it should be moving slower on one side and faster on other.

Unless everything in existence moves around the earth, Like I said was going to write a scifi story on that concept, where 0 time was for moving forward in time, like speed of light moves back, not saying the earth is center, saying the story of clocks to the moon does not make much sense. Unless it was just that they clocks were different, and why didn't anyone calculate 0 speed?
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qazplm Donating Member (1000+ posts) Send PM | Profile | Ignore Fri Dec-24-10 11:03 AM
Response to Reply #5
23. man you've taken one of the simplest
concepts of relativity and physics in general and made it really really complicated.

The faster you go, the slower time goes, in any direction. That's the basic truth that is borne out. We see it in experiments done in planes and satellites and day-to-day in our GPS system.

Of course, we are comparing this to a moving Earth which itself would have a time dilation with a truly stationary object as it passes it, but at the end of the day, it is all a function of velocity, go faster, time slows, go slower it speeds up with a continuum from 0 velocity to the speed of light.

Whether you are a rocket taking off from the Earth, or Mars or a stationary point, if each rocket leaves at the same instant and achieves the same velocity, they will have the same time slow-down on their clocks (even if the starting and ending times themselves may be slightly different because of the initial reference frame starts).
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mindwalker_i Donating Member (836 posts) Send PM | Profile | Ignore Mon Dec-20-10 11:42 PM
Response to Original message
6. There are actually two effects here
Edited on Mon Dec-20-10 11:46 PM by mindwalker_i
First there is relative motion and special relativity. Your comments earlier get close to this idea. There is no absolute speed of anything in the universe, only relative speed, so two rocket ships moving relative to each other will both see the other ship experience time dilation. I will see time slow down for you, and you will see time slow down for me. In the case where a rocket leaves Earth, we on Earth will see time slow down for the ship, but they will see time slow down on Earth.

The catch is this: for objects that undergo acceleration, time dilation happens only to them. So, for example, if someone were standing on a surface close to a black hole, we would see their time slow down. They would see our time speed up! Special Relativity deals with non-accelerating objects, like two rocket ships passing by each other but not firing their rockets. For all practical purposes when it comes to rockets, the Earth can be considered non-accelerating.

Rotation involves acceleration. So the Earth is rotating, and is is revolving around the sun, the sun is revolving around the core of the galaxy, and the galaxy is part of some cluster of galaxies, etc. The gravitational forces between objects are what cause the acceleration. Only these accelerations matter - the absolute speed does not matter and in fact, there really is no such thing. Relative motion matters for relative measurements of time but again, they always happen to the other guy. The acceleration could produce non-symmetrical time dilation if one body is subject to more acceleration than another. That could give us some data to make actual comparisons on the motions of different bodies.

Here's a little brain teaser. One effect of special relativity is Lorentz contractions. If, for example, you throw a baseball at relativistic speeds (good arm!), the baseball, according to all measurements you could make, would flatten into a pancake in the direction of motion. At the limit, it would be a flat circle flying face-first through space. Now imagine a merry-go-round spinning so fast that the rim is moving near the speed of light. That is guaranteed to produce some very unhappy children! But more to the point, the circumference will decrease because the rim is moving tangentially to the direction of motion. However, the spokes are moving perpendicular to the direction of motion and therefore will not get shorter. The value of PI is no longer constant! Essentially, you are dealing with a highly curves space-time. Weird things will happen (aside from thoroughly pissed off children), like the angles of a triangle will no longer add up to 180 degrees.

I did some calculations on how big a merry-go-round would have to be, such that the rim was moving ~90% light speed and the centrifugal force would be about the weight of a person. The merry-go-round would have to have the rim somewhere near the orbit of Pluto, so there are some engineering problems involved. But then, it occurred to me that it would be bad to build something like this that distorts space so much, when our sun is right in the middle of it.

Hope this clears it up a bit.
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bananas Donating Member (1000+ posts) Send PM | Profile | Ignore Tue Dec-21-10 01:37 AM
Response to Original message
8. The Twin Paradox
Edited on Tue Dec-21-10 01:40 AM by bananas
"So here is the question, why did time dilation happen on the trip to the moon, and then it was not canceled out on the return trip."

That's called the twin paradox, explained here: http://physics.about.com/od/timetravel/f/twinparadox.ht...
And here: http://en.wikipedia.org/wiki/Twin_paradox

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leahcim Donating Member (56 posts) Send PM | Profile | Ignore Tue Dec-21-10 11:57 AM
Response to Original message
11. I think you've missed that:
If a spaceship is going past the earth at 0.5c (say), someone on the earth looking at clocks on the spaceship will say that the clocks on the spaceship are running slow, but someone on the spaceship looking at clocks on the earth will say that the clocks on the earth are running slow. The situation between the spaceship and the earth is symmetric -- each sees themselves as still and the other moving, with the other's clocks running slower than their own.

You may think this would lead to a conflict if the spaceship and returns to the earth, but if the spaceship returns to earth, the situation is no longer symmetric, since in order to change direction the spaceship must undergo an acceleration, which introduces its own time dilation.
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Jim__ Donating Member (1000+ posts) Send PM | Profile | Ignore Tue Dec-21-10 03:46 PM
Response to Original message
14. "... why did time dilation happen on the trip to the moon, and then it was not canceled out ...
Edited on Tue Dec-21-10 03:50 PM by Jim__
on the return trip"

First, there are 2 components to time dilation, relative motion effects and gravitational effects. You seem to be talking about the effects of relative motion. Fine, let's just talk about that. And let's just address the question cited in the post title.

If the earth is moving .5 speed of light -> that way. And an object moves towards it at <-.25 speed of light, then time dilation would be backwards, since the earth would be moving faster and then slower in time. While if the object moved away from earth, then it would be moving .75 speed of light, and then you would see expected time dilation.

Let's just say that within it's reference frame, the earth is not in motion - we are free to choose our reference frame. So, when the rocket moves away from the earth it moves at some speed, s, with respect to the earth's frame of reference. Then when the rocket moves back toward the earth, it moves at some other speed, s+δ, with respect to the earth's frame of reference. On both trips, to the moon and back from the moon, the rocket is in motion with respect to the earth's frame of reference. Why would you expect the time dilation to cancel? Note that if δ > 0, then the time dilation on the return trip would be greater than the time dilation on the original trip; but time dilation occurs on both trips.

Time dilation depends on relative motion, not the direction of the motion. Note that the relative velocity may change based on the direction of motion, but the relative velocity will always be greater than 0, so there will always be some time dilation when there is relative motion.

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Confusious Donating Member (1000+ posts) Send PM | Profile | Ignore Sat Dec-25-10 10:17 AM
Response to Reply #14
26. You just could have said

Time does not run backward, only forward.
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qazplm Donating Member (1000+ posts) Send PM | Profile | Ignore Mon Dec-27-10 01:36 PM
Response to Original message
31. there is no location on the Earth
that is at "0 speed." The entire planet is moving very fast through space. Furthermore, the planet is rotating, so again in that scenario, other than I suppose the dead center of the planet, there is no part of the planet that is not rotating. Likewise, it is unlikely in an ever-expanding universe filled with gravitational forces that there are many if any objects moving with true "exact 0 speed."
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