Hasn’t this been the plot of many a sci-fi story, with the punchline or moral that history ends up worse for the meddling?
Article.
The gist: Joe Davis wants to send a radio message – an hourlong Morse code message listing numerous pandemics, natural disasters, genocides, and other tragedies that humans failed to mitigate or prevent between 1935 and 2011 – into the past by sending it towards the black hole Cygnus X-1, over 6,000 lightyears away, where it would slingshot off the black hole’s edge into the past and back towards Earth. With either irony or horrible foresight, he calls his message Swansong.
According to the article, the concept of bouncing a message off a rapidly spinning black hole is … at least not theoretically impossible. As a physicist states, “for all we know, the laws of physics might be like this, and we might be able to do this.”
I wonder what he hopes to accomplish. Given that Back To The Future-type timeline models where the world changes around you and you retain your memories are…problematic, I only see three possible outcomes to sending information into the past:
Fixed timeline model. Your message arrives and changes nothing, because the message had already arrived in your actual past and didn’t help anything.
Multiple worlds model. Your message arrives in a different (possibly new) universe. Things are different, possibly better there, but you’ll never know it. Maybe your mysterious message starts an worldwide religion, waiting for messages that never come.
Overwriteable timeline model. Your message arrives in the past, destroying the timeline after it (including you) and replacing it with an alternate timeline. Things are different, but you definitely never know it, because the version of you that sent information into the past no longer exists. And there’s also a worldwide religion that, after getting no more messages, turns into an apocalyptic cult and kills everybody.
Wait, wait. If you sent a message back and it created an alternate universe and you were not in it, how could a non-you ever be the future trying to send a message back, thereby creating an alternate universe where you are not there??
Wait. Wut?
That’s like the snake who starts eating his own tail.
Hmm? If you in universe A sends a message that creates a new universe B, that universe may or may not have a you-B. This you-B might be similar to you-A, or drastically different from you-A, or might not even exist (perhaps your parents never met in the other universe).
If your message fixed the problems it was trying to fix, then you-B will not be trying to send a message back to fix them again, because in her understanding there would be nothing to fix. However if your message failed to fix the problems, then perhaps you-B would strike on the same approach, and send another message back…creating a universe C.
It’s worth noting that if the message you send back is utterly ineffective, then the timelines of all the universes might look exactly the same - and since nondeterminism is a lie that would mean that the message that you-X decides to send back would be exactly the same each time. Which would mean that an infinite number of new universes would be created, each due to the you in the prior universe trying and failing to make a universe with a past that is better.
If the letters are not utterly ineffective (and never converge on one that is), then that would result in eventually one of the messages changing the universe enough to fix the problems - or to have wiped you-X out of existence in that universe. In either case that would mean only a finite number of universes would be created by your plan to change the past.
Wouldn’t that mean a loop? Like, where it turns out that universe A was created by one one of the universes it spawned?
That can’t happen, of course. In a model where existing universes are modified no other universes are created; in a model where new universes are created no existing universes are modified.
But the snake will still be alive, albeit with some or all of its tail in its mouth, but the smart ass time travel guy won’t be (or at least as far as I can tell ). So I would have to say his plan sucks for him.
Let’s say I’m, uh, ‘me-B’ — in that, just this morning, I got a message from ‘me-A’ in the future: “DON’T ORDER A PIZZA TODAY!” So, okay; I don’t. Oh, I would’ve; but I figure ‘me-A’ is a pretty together guy and had something to fix and knows what he’s doing.
I can assure you: tomorrow afternoon, I’d have no problem whatsoever sending a message back in time about, y’know, not ordering a pizza. I don’t know what bad outcome I just averted by following the advice of ‘me-A’, but I don’t need to know; I can, and would, just shrug and pass it along.
If I ever get sent winning lottery numbers in the same fashion, and promptly get rich, I’ll again be glad to shrug at some point in the future and pass that info along. I don’t much care whether some ‘me-A’ who didn’t get rich sent that info to ‘me-B’; what matters is whether I, having gotten rich, will now choose to send that info back.
As a physicist states, “for all we know, the laws of physics might be like this, and we might be able to do this.”
). So I would have to say his plan sucks for him.