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The problem I'm seeing with all this is that it seems to assume an absolute reference frame from which it is possible to say that one has move 10 years into the 'past' or the 'future' (in relation to what?). But my understanding is that this is not how relativity or the universe works.

Also, it feels like you're ignoring the frame of reference of both Beta and Gamma, within whose reference frames it took 50+ years (83+years actually) for the ships carrying the wormholes to get there. Also, it would take 66.67 years from the frame of reference of the ship(s) to travel 50 light-years at .6c, not including accel/decel time (which may or may not be ignorable for the purposes of this thought experiment).

On a related note- this page HERE might help with any calculations.

My 2c worth,

Todd
(02-13-2017, 07:19 AM)Drashner1 Wrote: [ -> ]The problem I'm seeing with all this is that it seems to assume an absolute reference frame from which it is possible to say that one has move 10 years into the 'past' or the 'future' (in relation to what?). But my understanding is that this is not how relativity or the universe works.

No we're using the systems (specifically alpha) as the reference frame. From Alphas perspective Bob would look like he's travelled ten years into the past because if they look through a telescope they would see him pop out of the wormhole the instant he stepped in. Given that they know the distance to Gamma he would appear to have travelled ten years into the past. Likewise with Alice in the opposite direction (it would take them twenty years to make the observation she travelled ten into the future).

(02-13-2017, 07:19 AM)Drashner1 Wrote: [ -> ]Also, it feels like you're ignoring the frame of reference of both Beta and Gamma, within whose reference frames it took 50+ years (83+years actually) for the ships carrying the wormholes to get there. Also, it would take 66.67 years from the frame of reference of the ship(s) to travel 50 light-years at .6c, not including accel/decel time (which may or may not be ignorable for the purposes of this thought experiment).

Ah yes that is an error in my working out. The wormholes would be displaced by 16.66 years in time, not ten. It's too late to work it all through again (the outcome will still be the same, no time travel and disagreeing calendars), I'll write up a correct version for posterity tomorrow.

The acceleration time can mostly be ignored, especially if we consider 0.6c as representing the average speed and time dilation.

(02-13-2017, 07:19 AM)Drashner1 Wrote: [ -> ]On a related note- this page HERE might help with any calculations.

Cheers!
God damn it I don't think I'll be able to get to sleep until I've worked this out properly...
• Alpha system is 50 light years away from Beta and 50 light years away from Gamma.
• At some point in the past Alpha made a wormhole pair and sent one to Beta at 0.6c
• The wormhole took 83.33 years to arrive. Due to time dilation from the perspective of the linelayer (and Alphans looking through their wormhole) the journey took just 66.66 years.
• Travelling through the wormhole from Alpha to Beta puts a traveller 16.66 years into the future from the reference frame of Alpha but causality is preserved because they are 33.33 years out of their future light cone.
• At some other point in the past Gamma made a wormhole pair and sent one to Alpha at 0.6c. Entering the AG wormhole would take an Alphan 16.66 years into their past, but again 33.33 light years outside of their historic light cone.
• A Betan travelling through both wormholes (BA-AG) would arrive at Gamma 33.33 years in their past. To preserve causality Gamma and Beta must be >33.33 light years away. For the purpose of this thought experiment we'll assume they're a negligible distance above 33.33ly distant.
• Bob and Alice start in Alpha on the 1st of Archimedes, 9000a.t. Bob takes AG to Gamma and Alice takes AB to Beta.
• Upon arrival they both immediately set out in a spacecraft towards each other, each travelling at 0.6c relative to Alpha/Beta/Gamma.
• From the perspective of Claire (many decades later) watching from Alpha by telescope Bob exits his wormhole first, 16.66 years before he left Alpha.
• Claire observes Alice exiting her wormhole 16.66 years after she left Alpha.
• By the time Alice exists her wormhole Bob has travelled 20ly. Due to time dilation he measures this as 16 years.
• When Alice leaves Beta her and Bob are 13.33ly apart.
• It takes 11.1 years (as measured by Claire) for the pair to finally meet.
• For Alice 8.88 years have passed. Her calendar shows it to be some date in the month of Kepler, 9008a.t.
• For Bob 25.33 years have passed. His calendar shows it to be some date in the month of Darwin, 9025a.t.
• For Claire, observing this as the light comes in, 27.76 years have passed since Alice and Bob left. Her calendar shows it to be some date in the month of Imhotep, 9027a.t.

Right then. That should all be correct. Bed time.

P.s. If we have to do this again I vote the distances between alpha and the other systems be changed to 60ly. It makes the maths a lot easier, nice round numbers.
All of this seems to be a strong argument for having all of your wormholes essentially radiating outward from a central point, as we do have them in the structure of the Nexus.

Todd
It will always be approximate, but this is the sort of situation where the "first light" metric can provide a baseline for calculating time. One can refer to "first light" dates in the above scenario and be within a few minutes of correct for measuring relative to the timeframe of any locations with "low" relative velocity.

When the light emitted from Sol on 1 Archimedes AT 0 arrives at a place, minus the number of light years distance it is from sol, is the "zero" date for the first-light metric. So we could talk about a "standard" time, although technically it would always be time relative to Sol.

A weird little thing with it though, would be that systems depending on their velocity relative to Sol would need to adjust their clocks every so often to stay on the first-light metric. In practice this should never amount to more than the "leap second" adjustment we add to some years due to days getting steadily longer (because of tidal energy transferring energy to the orbit of the moon) since seconds were standardized.
Hrm. The issue of 'standard time' has come up before and Adam pretty thoroughly stated that it's physically impossible.

I think that I would prefer to reach out to Adam and get his input on this entire issue. Several things still feel off to me about this entire scenario.

Todd
IIRC physically impossible to be exactly right about it over interstellar distances. In any case for the Nexus the issue is much simpler. Given that Haward class wormholes can be placed very close together (theoretically as close as 5 micrometres for a 1 nanometre diameter pair, practically a few tens of kilometers apart due to the intense gravity) if you're docked with your Haward relay node you can chat to any other node in a very short amount of time.

Quick idea running some numbers: lets consider 1 nanometre wormholes. They mass 6.743e19 kilos which makes their surface gravity insane. At 22km distant the gravity is about 1g so lets imagine a bog-standard Hayward Node is a shellworld hab 44km wide, with communication arrays all across the surface and the wormhole sitting in the exact centre. In a relay system 100 Hayward wormholes are arranged in a dynamically stabilized Klemperer Rosette with each node one light second from its neighbours. A Haward relay is therefore a circular arrangement with the furthest distance between nodes being ~30 light seconds.

The nexus is 5 levels deep. If you're standing on your system's Hayward node and you're calling someone on the far side of the Nexus standing on their system's Hayward node the longest possible time it would take messages to travel between you is five minutes. The shortest possible time is ten seconds.

Of course that scenario is quite contrived, you may be light hours or more from your local Node and the Rosettes larger than half a light minute. But in any case communication between parts of the Nexus should be good enough through the network to maintain synchronised clocks.

EDIT: Doing some searching I found this paper from the 90s that suggests we might be able to identify distant interstellar civilisations using neutrino pulses to synchronise distant clocks: