[eigenket]

Ah I guess I misunderstood what was being claimed. I thought the claim was "you can use entanglement to instantly send messages", but it's actually "you can use entanglement and this model of how time travel might work to send messages instantly".

Obviously these are rather different. In fact I feel like the entanglement doesn't even help in the time-travel protocol. If you want to send messages instantly and you can send messages back in time, you can "just" send yourself the message distance/c seconds in the past and send it then. Some messing around let's you arrange for it to arrive at exactly the time you want to send it in the future.

[lrschaeffer]

Assuming what I wrote above is correct (I don't actually know anything about closed time-like curves), it's actually weirder than just going back in time and mailing a letter early so it arrives when you want. Specifically, once you set up the entangled state, no other communication between the parties is necessary.

[eigenket]

Yeah I understand the proposed protocol using entanglement. I'm just saying that if you're assuming we have access to the ability to send messages back in time there are much simpler protocols to achieve instant communication /without/ having to do anything involving entanglement.