Time travel doesn't exist because time travel wiped out the timelines where it did

[Umbran]

Everything we know about how time travel might possibly work requires huge amounts of energy at the very least. That is a thing that is true.

Yes, but everything we know about how time travel might possibly work also involves materials that don't exist, and/or that we cannot manipulate, in configurations that should not be physically stable. Like, infinitely long, rapidly rotating cylinders of neutronium.

How we think it "might possibly work" is irrelevant, unless you posit that we get it by incrementally improving our ability to do it by one of the methods we currently think it might possibly work.

If instead you posit we get it though some fundamentally new science, then the old considerations go poof.

If we assume a fantastical easy time travel

We are assuming fantastical things with ANY time travel. There is no time travel that is not fantastical.

 

[Reynard]

We are assuming fantastical things with ANY time travel. There is no time travel that is not fantastical.

Then there is no argument to be made. Time travel can be anything. It's pure fantasy. It only has value as philosophical discussions about what to do with it.

 

[The Firebird]

So...not science. Not really math, either. Kind of just half-assed metaphysics. Is that what "informatics" is?

It's a newer term encompassing anything data heavy in the sciences and elsewhere. In biology it goes by "bioinformatics", in chemistry "cheminformatics". But there is also some overlap with data science and computer science.

I don't know much about the particular informatics program but I wouldn't reject it on those grounds.

 

[GMMichael]

So, I skipped a few pages, but did we cover the angle about time being part of space, "spacetime," and therefore probably not separately navigable from space?

Or the quantum worlds angle of: everything happens, but we only see what's probable? So time travel is just not very probable?

 

[Corinnguard]

So, I skipped a few pages, but did we cover the angle about time being part of space, "spacetime," and therefore probably not separately navigable from space?

Or the quantum worlds angle of: everything happens, but we only see what's probable? So time travel is just not very probable?

We haven't reached those spacetime coordinates yet.

 

[Umbran]

Then there is no argument to be made. Time travel can be anything. It's pure fantasy. It only has value as philosophical discussions about what to do with it.

Bingo! You've got it!

Now, you can discuss pure fantasy in terms of its internal logic and consistency just fine. But arguments of the form, "That's not how magic would really work," are generally bogus.

 

[Umbran]

So, I skipped a few pages, but did we cover the angle about time being part of space, "spacetime," and therefore probably not separately navigable from space?

If we are taking that view, your statement is kind of like saying that left-right is not navigable separate from forward-back, which is clearly wrong. I can walk forward without walking right.

Or the quantum worlds angle of: everything happens, but we only see what's probable?

That's not the quantum world angle. In the Many Worlds interpretation, all possibilities exist and are realized in their own timeline/universe. You only see one of them.

Whether your consciousness is in one of the "more probable" timelines is a matter of definition, conjecture, or argument. Since all possibilities are realized, in a sense all universes that can happen, do happen with 100% certainty, not some greater or lesser probability. In another sense, you can take the sum total of all timelines, pick one, and say that it is "more/less probable" depending on how many other timelines are similar to it.

 

[Umbran]

This is my favourite sentence from the article: "In a new study, Andrew Jackson—a research associate from the School of Informatics—explores reasons beyond the scientific or technological as to why time travel appears to be impossible (at least, in this reality)."

So...not science. Not really math, either. Kind of just half-assed metaphysics. Is that what "informatics" is?

"Informatics" is the study of computational systems. In much of Europe, it is synonymous with "computer science". Typically, it is used in the context of recasting information to be something useful to humans. In this context, it may be mean "the science of information processing".

 

[MoonSong]

We are assuming fantastical things with ANY time travel. There is no time travel that is not fantastical.

Kinda. There is a good mathematical and physical framework to justify time travel due to extreme but naturally happening circumstances. The catch is that to make use of them you need practical FTL for which there is a theoretical model (Warp). Then we get into the problem that for warp to move faster than light, we need an object to open the path that is already moving faster than light, and that you need the ability to command a black hole and that you'd be crushing everything in your path, and the enormous amount of energy needed to create the warp field... I mean, in the end it is all fantastical, but we start with a plausible basis.

Just like with aliens.

 

[Umbran]

Kinda. There is a good mathematical and physical framework to justify time travel due to extreme but naturally happening circumstances.

No.

Einsteinian Relativity does not prohibit closed timelike curves through spacetime (which is what you call time travel in relativity). But the solutions that have closed timelike curves are not "extreme but naturally happening". They are things like infinitely long cylinders of neutronium that are spinning evenly along their entire length such that their surface speeds approach the speed of light. Or they are wormholes that need large amounts of exotic matter to not instantly collapse (where "exotic matter" is polite code for "materials that don't actually exist or have never been observed to occur in nature"). We have exactly zero evidence of a closed timelike curve ever occurring in nature.

The catch is that to make use of them you need practical FTL for which there is a theoretical model (Warp).

Again, not quite.

In Einsteinian Relativity, there is no distinction between "time travel" and "FTL travel" - space is not separate from time. Once you have practical FTL, you already have a time machine, no further gyrations are needed - fly the right direction at FTL, and you can arrive back at your starting point before you left. And, vice-versa, time travel implies FTL travel.

I mean, in the end it is all fantastical, but we start with a plausible basis.

"Plausible" is not an objective term.