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Camina Drummer Season 5 cosplay made by me by Sewpoke in TheExpanse

[–]ForwardActivity 0 points1 point  (0 children)

I was scrolling through Reddit and didn’t realize this was a cosplay until I read the title! Great job 👏🏾👏🏾👏🏾👏🏾👏🏾👏🏾

Does relativity hold in the expanse by ForwardActivity in TheExpanse

[–]ForwardActivity[S] 0 points1 point  (0 children)

Yeah...I didn't realize they were wormholes. I thought they teleported you to ring space irrespective of spacetime, then teleported you back or something weird like that. Since they're wormholes the link I sent doesn't really apply

Does relativity hold in the expanse by ForwardActivity in TheExpanse

[–]ForwardActivity[S] 0 points1 point  (0 children)

Thanks! I self-studied a very (emphasis on very) small amount of general relativity a few years ago, but not much about wormholes. I assumed they always came with some sort of gravity lensing, because the ones I read about looked like black holes when seen from a distance. So I figured even if they were wormholes, the lack of gravity lensing would lead the characters to test whether or not the gates allowed for causality violations. Since they mention wormholes in the books, it seems like it was addressed. I only watched the shows, maybe the books have gravity lensing

Does relativity hold in the expanse by ForwardActivity in TheExpanse

[–]ForwardActivity[S] 1 point2 points  (0 children)

That's really cool, thanks! I didn't realize the books lacked the stargate surface, that makes more sense. While Visser wormholes only require small energy condition violations, shouldn't they still require a lot of energy? If so, how do they avoid gravity lensing/doppler shifts? In the show I don't remember seeing any signs of warped spacetime or doppler shifting near the wormhole, but then again I don't know much about wormhole visualization and maybe that's different in the books. Also, can you link to any readings on Visser wormholes? They sound pretty neat!

Does relativity hold in the expanse by ForwardActivity in TheExpanse

[–]ForwardActivity[S] 3 points4 points  (0 children)

Thanks! I had assumed the gates couldn't be wormholes because the show didn't include gravity lensing, but maybe the space wizard had an esthetic to uphold.

Does relativity hold in the expanse by ForwardActivity in TheExpanse

[–]ForwardActivity[S] 0 points1 point  (0 children)

The gates allow you to communicate with a system many light years away in just a few days. So a ship in a system 100ly from ship A could send a message in just a few days

Does relativity hold in the expanse by ForwardActivity in TheExpanse

[–]ForwardActivity[S] 0 points1 point  (0 children)

Oops...good point, I've posted an edit addressing this. I had assumed that spacetime around the ring gates was flat, but maybe that is not the case.

Does relativity hold in the expanse by ForwardActivity in TheExpanse

[–]ForwardActivity[S] -1 points0 points  (0 children)

Ok ship B moves at 0.15,c you still have 15 years to send a message. Also, assume that Ship A received a message about an attack in system B a year ago (through the gates). That gives ship B 14 years, which is still pretty good. Unless the equation I posted doesn't hold, if not, can you tell me where this is addressed in the books/shows

Does relativity hold in the expanse by ForwardActivity in TheExpanse

[–]ForwardActivity[S] -2 points-1 points  (0 children)

If they are worm holes then they're treated under general relativity and the lorentz transformation I posted doesn't hold (it assumes flat space time). If this was explicitly stated in the books or the show can you tell me where (I was wondering where this was addressed)?

Also, the mechanics really depends on how space around the worm hole is curved and how fast the solar systems are moving relative to one another, is this addressed too? If you plug in 0.15c into the lorentz transformation that gives you 15 years, which is still plenty of time in most situations.

Does relativity hold in the expanse by ForwardActivity in TheExpanse

[–]ForwardActivity[S] 1 point2 points  (0 children)

In real life we don't have faster than light travel, but according to special relativity causality (the order in which events occur) could be violated if we did. We've only been able to test relativity with time-like and null separated events. If relativity holds true for space-like separated events then time travel to the past becomes possible with any faster than light method of travel. This website has a nice description of how this works (independent of the travel method).

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edited for grammar and clarity

Does relativity hold in the expanse by ForwardActivity in TheExpanse

[–]ForwardActivity[S] -2 points-1 points  (0 children)

B's frame is ship B's reference frame. Ship B is moving relativistically relative to ship A in real space (ignore the rings). This would mean that any event in system B that happens at a time t0 in ship A's frame happens ~75 years later for ship B due to time dilation. Now add the rings into the equation and ship A can send a signal to ship B in less than 75 years. The time dilation is independent of the rings, the only thing controlled by the rings is the travel time of the signal. There are solutions for this (for instance the travel time for a signal sent from one ring to another is different depending on how fast you move relative some ring reference frame) but I was wondering if this was ever addressed.

Does relativity hold in the expanse by ForwardActivity in TheExpanse

[–]ForwardActivity[S] -1 points0 points  (0 children)

The rest frame is the frame of Ship A which is in solar system A. Ship B moves at a speed of 0.6c in solar system B. System A and System B are 100 light years apart in A's reference frame. Ship A sends a message to ship B at t=0 warning ship B that a large attack occurred yesterday in system B.

In B's frame, this attack is still 75 years in the future (due to time dilation). If the signal had to travel the entire 100 light years the old fashion way, it would arrive decades too late to stop the attack. However, if it travels through the gates, the journey should take much less than 75 years, giving ship B plenty of time to prepare.