/sci/ - Science & Math

>>14983227
you can't travel through time, but you can send messages

https://youtu.be/Qd77OXWC1eg

>>14983227
Very much possible. Read Closer Encounters by Jason Reza Jorjani.

>>14983466
>Very much possible.
and why should we believe him? what facts from the past/future did he return with? How did he travel in space to wherever the Earth was in space at that particular time?

>>14983472
Read the book.

>>14983227
>How do closed timelike curves work?
They don't, at least not in Minkowski-space. The path MUST become spacelike (i.e. forbidden) along part of the curve.
And you can't do it with a Schwartzchild metric or any of its derivatives because the spacelike portion is even more dominant.
You need a metric supported by negative energy density—ABSOLUTE negative energy.
There are excellent reasons to think you can't have that.

>>14983474
>Read the book.
why not just read the Time Machine or some other novel?

>>14983227
>How do closed timelike curves work?
by connecting two different points in time to one another causally, hence the term "causal loop"
>Is time travel possible?
theoretically, yes, but only with closed timelike curves (which must obey the Novikov self-consistency principle) as far as we know
with parallel timelines things would get a lot more complicated fast
watch Dark for an excellent handling of closed timelike curves (although they also introduce parallel timelines, but only so few that it doesn't become overly complicated)
alternatively read By His Bootstraps by Heinlein, or watch the movie Predestination that's an adaptation of it

>>14983227
>>14983592
my bad, Predestination is based on All You Zombies by Heinlein
I got them mixed up because they both involve closed timelike curves
both are definitely worth a read

>>14983592
>by connecting two different points in time to one another causally
>hence the term "causal loop"
How would you connect two events causally?

Is it possible to get stuck in a causal loop through infinite/eternal regress?

>>14983523
Because he provides proof.

>>14983708
>How would you connect two events causally?
well, there are many examples provided in those works I mentioned, if you don't mind reading their synopses
there's this diagram from Wikipedia that might make it easier to understand visually
>Is it possible to get stuck in a causal loop through infinite/eternal regress?
well, the thing is that you actually avoid infinite regress with a causal loop, because there's no recursion
and as for whether or not you could get stuck, the thing is that you need to at least "renew" the object going through the causal loop for that to occur, since it must be the exact same objects emerging every single time (hence why the notebook in By His Bootstraps is copied), so for you as a human to get stuck in such a causal loop you'd have essentially become "renewed" in the same way, perhaps through cloning and consciousness transfer, or by some other scientific means not within our reach
this would make you a so-called "jinn" in the context of causal loops, which is an object without any actual origin
it has even been posited that the entire universe is actually such an object, which would make everything "stuck in a causal loop", and lend credence to the idea of eternal recurrence, but I doubt that this is really the case
in any case, if you're not "renewed" in that manner, then you will not "get stuck" in the causal loop, as you would simply relive the loop as a version of yourself that's further advanced, and at some point you'd exit the loop completely (although you could go through the loop several times, in e.g. Dark there are three versions of everyone corresponding to the three primary instances of looping)

>>14983734
>Because he provides proof
What is the proof? I'm not reading your book, flag.