# Relativity: What conditions define a spacetime path

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#### ralfcis

Wow I just got kicked off another forum. That makes 4 plus one I left voluntarily. I actually got the answer to my question and was just waiting for confirmation that I had it right before boom, the boom came down. The place had talent I must say. The answer was very complex but I could peddle that around looking for confirmation.

#### topsquark

Forum Staff
It's starting to sound like you are looking for someone that agrees with you, rather than looking for an acceptable explanation. I may be wrong.

We don't have specific "experts" in any field but there are two that will probably find this thread at some point. As you seem to disagree with the (standard) explanation I'm not sure what more to say. Whether you agree with me or not what I posted is the "standard" answer. I don't know what you are looking for.

So what is this non-Relativistic method to explain the Twin Paradox?

-Dan

#### ralfcis

A guy on another forum is schooling me on the correct relativistic method to explain how age difference in the twin paradox unfurls. I haven't got the final answer yet. He's definitely the expert I've been looking for as he understands everything I've been saying and why it's faulty but I can't quite yet understand what the correct method is. He said the math I showed him works but it's not the math relativity uses. I don't think he's revealed the correct method yet or he hasn't put a glowing neon sign around it for me to recognize.

My incorrect interpretation of relativity (which is not my personal theory's interpretation) is that time is not what clocks measure, age is what clocks measure and the rest is in the form of distance separation at speed. When Bob and Alice separate, their mutual distance increases which has a time value not seen on their clocks because in relativity, the faster one is observed to move through space, the slower he is observed to move through time. When neither changes their relative velocity, the time stored as distance is subject to relativity's formula of proper time squared = t squared - x/c squared.

If Alice does two 3ly legs without a change, her clock will say 8 but there are two yrs of distance time which must be subtracted from Bob's perspective time of 10. So there's no age diff between the two.

But if Alice makes a change, then she has established she's the one moving through space so no time from the equivalent distance is subtracted from Bob's time of 10. Her age of 8 already reflects the loss of 2 yrs due to her travels through space. Hence a 2 yrs age difference is established between the two. The age difference unfurls at the steady rate of - .25 yrs for every yr alice travels. The same is reciprocally true from Bob's perspective until either one makes a change that turns the perspective into reality. That -.25 yrs does not register on a clock and registers only as travel distance at speed. 3ly travel at .6c converts to 1yr time that doesn't appear on a clock.

I asked him to show me the numbers the correct relativistic method provides for this example. That will definitively reveal whether the age difference unfurls slowly and at what rate and where during the journey.

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#### ralfcis

Here's the explanation of how age difference unfurls (it doesn't). Enjoy!

"she would know that Bob was the one who was stationary in regard to experiment's starting frame and that he was travelling only in time."

All wrong. Bob may have never been stationary wrt Alice if Alice flew past him at the start. (The start is significant for the co-location of the two, not their relative velocity.) Bob was depicted as stationary but he had the same relative velocity as Alice during the journey. He was also moving at .6c through space relative to Alice despite that the STD depicts him as not going anywhere. The starting frame was not Earth or the entire background universe. The starting frame just had Bob and Alice, the background doesn't matter. That's a separate frame; confusing because that separate frame is always included in the STD as the background cartesian coordinates. STDs are very bad for causing everyone's confusion and especially for implying a preferred frame.

He was also not the only one travelling through time. Both were travelling through time at the velocity of light through time which manifests itself as the normal rate of time. For example, a VCR has slow motion, fast forward and play. Play is the normal rate through time. The other two are other velocities of time through time. The doppler shift ratio is like a VCR where the two can see each other at different apparent time rates but they see themselves at the normal time rate. Everyone in his own frame passes through time at the normal time rate which is the maximum rate events can progress through time.

So at first Bob and Alice were both moving at c through time and at, let's say, .6c through space. They saw the doppler shift ratio from each other, manifest as the tv signal they broadcast of their daily lives, as half speed slow motion. They both looked to be moving in slow motion from the others perspective and so were the others clocks even though everything within their own environment was looking normal. From that they could calculate their relative velocity was at .6c and from that they could calculate their time dilation as .8 of each other. For every year one was ageing, the other was ageing .8 yrs from each other's perspective. From other perspectives moving at different relative velocities to them, the ageing rates were something else. Also don't get confused with their ageing rate due to time dilation and the apparent rate they seem to be ageing due to the doppler shift ratio and the age difference between them at re-unification, which is not due to any universal ageing rate. It's a one-time endpoint number that had as many derivations as perspectives watching it get there.

The person who initiates a change in relative velocity that ends in their unification, will be the one who ends up ageing less than the other because his spacetime path is proven to have been through space and therefore less through time. (I don't know how relativity establishes that proof because if the guy on earth performs the velocity change, he is still at the same point where he started while the other guy isn't.) However that determination can't be made until they re-unite because any distance separation before that point brings in perspective from other frames. Any determination of age difference has to be referenced to the frame making that determination. It's only when they are together that the universe can say what their age difference is from all perspectives (the same) and hence, independent of perspective just like c which is also independent of perspective.

You need to forget everything you've ever been taught from wiki articles, popular science magazines, people on forums, on-line mickey mouse courses and probably most books.

P.S. I suspect the proof of who actually travelled through space is somehow connected to who entered the 0 velocity common frame (a party has to stop at some point temporarily to make a turnaround). Is this the lost spacetime path rule that explains why Alice can make a stop at a distance from Bob and still have a valid age difference with him? It's like the spacetime path doesn't need to go all the way to re-unification if the party runs out of gas trying to make it there and sends a note of apology. The age difference is established when the note reaches the other party.

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#### topsquark

Forum Staff
Here's the explanation of how age difference unfurls (it doesn't). Enjoy!

"she would know that Bob was the one who was stationary in regard to experiment's starting frame and that he was travelling only in time."

All wrong. Bob may have never been stationary wrt Alice if Alice flew past him at the start. (The start is significant for the co-location of the two, not their relative velocity.) Bob was depicted as stationary but he had the same relative velocity as Alice during the journey. He was also moving at .6c through space relative to Alice despite that the STD depicts him as not going anywhere. The starting frame was not Earth or the entire background universe. The starting frame just had Bob and Alice, the background doesn't matter. That's a separate frame; confusing because that separate frame is always included in the STD as the background cartesian coordinates. STDs are very bad for causing everyone's confusion and especially for implying a preferred frame.

He was also not the only one travelling through time. Both were travelling through time at the velocity of light through time which manifests itself as the normal rate of time. For example, a VCR has slow motion, fast forward and play. Play is the normal rate through time. The other two are other velocities of time through time. The doppler shift ratio is like a VCR where the two can see each other at different apparent time rates but they see themselves at the normal time rate. Everyone in his own frame passes through time at the normal time rate which is the maximum rate events can progress through time.

So at first Bob and Alice were both moving at c through time and at, let's say, .6c through space. They saw the doppler shift ratio from each other, manifest as the tv signal they broadcast of their daily lives, as half speed slow motion. They both looked to be moving in slow motion from the others perspective and so were the others clocks even though everything within their own environment was looking normal. From that they could calculate their relative velocity was at .6c and from that they could calculate their time dilation as .8 of each other. For every year one was ageing, the other was ageing .8 yrs from each other's perspective. From other perspectives moving at different relative velocities to them, the ageing rates were something else. Also don't get confused with their ageing rate due to time dilation and the apparent rate they seem to be ageing due to the doppler shift ratio and the age difference between them at re-unification, which is not due to any universal ageing rate. It's a one-time endpoint number that had as many derivations as perspectives watching it get there.

The person who initiates a change in relative velocity that ends in their unification, will be the one who ends up ageing less than the other because his spacetime path is proven to have been through space and therefore less through time. (I don't know how relativity establishes that proof because if the guy on earth performs the velocity change, he is still at the same point where he started while the other guy isn't.) However that determination can't be made until they re-unite because any distance separation before that point brings in perspective from other frames. Any determination of age difference has to be referenced to the frame making that determination. It's only when they are together that the universe can say what their age difference is from all perspectives (the same) and hence, independent of perspective just like c which is also independent of perspective.

You need to forget everything you've ever been taught from wiki articles, popular science magazines, people on forums, on-line mickey mouse courses and probably most books.

P.S. I suspect the proof of who actually travelled through space is somehow connected to who entered the 0 velocity common frame (a party has to stop at some point temporarily to make a turnaround). Is this the lost spacetime path rule that explains why Alice can make a stop at a distance from Bob and still have a valid age difference with him? It's like the spacetime path doesn't need to go all the way to re-unification if the party runs out of gas trying to make it there and sends a note of apology. The age difference is established when the note reaches the other party.
There is no distinction between the "speed" of your clock and the "speed" of your aging. Muons don't have a clock and nor do they age. But we can see them due to cosmic rays from Earth because their half-lives are undergoing a time dilation.

But no matter how you want to slice it I do recall the concept of "meeting" the other twin to have a bearing. Frankly I admit I don't understand it that well myself.

Oh, one last thing.

You need to forget everything you've ever been taught from wiki articles, popular science magazines, people on forums, on-line mickey mouse courses and probably most books.
I admit that there is much more in the Universe for me to learn and I grant that I sometimes make mistakes. But coming from a person who is on an online forum and have been taught using many texts I rather take exception to this comment. You previously indicated you are arrogant. That is not a problem in my book. You have also said that you have tried to get an answer to your question on many Fora. Fine. But it would appear that you took time out to write this sentence to give a general condemnation. Being arrogant and being insulting are two very different things.