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If an observer on Andromeda moves forwards and backwards their notion of now here on Earth sways back and forth over hundreds of years

Why don't we constantly oscillate over hundreda of years whenever a spatially separate observer moves?

Does the plane of simultaneity associated with spatially separated observers not lead to multiple versions of each observer per reference frame

For example a plane of simultaneity may crosscut my past therefore a different version of me experiencing my past exists in another reference frame, therefore there's millions of copies of me one per reference frame. Or is this a misunderstanding. Instead relativity does NOT imply multiple versions of each observer, one per reference frame. You are where you are, however I can apply different coordinates to your spatial and temporal position that may contrast with yours but it doesn't mean you are somehow duplicated when you're at these contrasting coordinate in my frame.

When we meet up our coordinates roughly line up so we don't notice this.

So it's not like I'm always interacting with a version of you who has conscious experience that contradicts your own in your frame

Instead it's a matter of labels and coordinates?

THANKS

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  • The guys here try to prove that there is a manifold of simultaneity, but it is – or would be – physically unobservable, which is a major obstacle for them. As you can see they have limited success proving their points. Van Flandern's essay on GPS satellite synchronisation is probably the easiest to grasp. Commented Feb 7, 2023 at 20:12
  • Does it change anything about how we think of other observers. Or do we just say observers carry their own clocks. Nothing weird happens to them in different frames
    – Danny55
    Commented Feb 7, 2023 at 20:14
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    It it is true, nothing weird happens. Everything exists simultaneously but clocks run at their own rates in their own frames. Commented Feb 7, 2023 at 20:17
  • So does it change how we think about the experience of other observers?
    – Danny55
    Commented Feb 7, 2023 at 20:19
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    Yes, relative to you, for them time may be flowing faster or slower. The most extreme situation is if you enter a gravitational singularity, as amusingly described by Stefan Hensel here. Commented Feb 7, 2023 at 20:55

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You seemed to answer your own question, but I'll add this anyway.

a plane of simultaneity may crosscut my past therefore a different version of me experiencing my past exists in another reference frame,

yes, and that plain of simultaneity will pass through alpha centauri in four years. And when it does, the alien with a telescope we'll see you different than you will be then. There will be two copies of you, separated by 4 light years of space and 4 years of time.

therefore there's millions of copies of me one per reference frame.

One per observer. Any number of them. And they're all you — specifically, the gravity waves and light you created are spreading out across the universe.

But that's all you are to anyone else unless you touch them, even if they're standing in the same room with you.

it doesn't mean you are somehow duplicated when you're at these contrasting coordinate in my frame.

In a sense, you are continuously being duplicated, because you broadcast your existence out to the universe through gravity waves and emitted light, and other ways you distort the universe. These distortions propagate at c.

Unless you touch somebody, these remote distortions are the only mutual existence you'll ever have with anyone.

When we meet up our coordinates roughly line up so we don't notice this.

When you're close together in the same room, then you don't notice it. That's because the speed of light is so fast. When NASA talked to the astronauts, there was a two-second delay because NASA was actually talking to someone in the past.

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