I’ll posit a 5th option: The emergence of a super intelligent AI thats mastered certain technologies and is trying to hide its presence. Any sufficiently advanced technology would appear as magic/alien to us.
I also have always had a problem with the dismissal of FTL travel. “It cannot be therefore it must not be” is not at all sound logic given our history with technology. If you went back in time and gave the queen of England a nuclear submarine, could she reproduce it? Her best and brightest advisor would look at its propulsion system and declare “It cannot exist therefore it must not be what it appears because only the wind can move you through the water!” You’d be relegated to the same categories as the scientists who said traveling faster than sound was impossible. The standard model of physics IS WRONG and we know it, just like newtonian mechanics ultimately was wrong. Just because we cannot fathom FTL does not preclude its existence.
There is an important difference here. In the history of technology, "high-level disciplines" may sometimes be "overthrown" and completely be rewritten frequently, making something impossible to be possible. But it rarely occurs in foundation of mechanics. Even it has been revisited multiple times in the past 200 years, things that were impossible in the past is still impossible now, and possibly in the future, at least from a macroscopic scale.
The mere existence of a nuclear submarine navigating the ocean in 1800s England, as an object, is compatible with the Newton's Laws of Motion. Although nuclear reaction itself violates other known physics at the time, But if compared to Newton's Laws of Motion, they are not as important. And nowadays, Einstenian mechanics have replaced Newtonian mechanics, and it has the same status as Newtonian mechanics had before.
That is, among all rational conclusions, those that is directly based on the foundation of mechanics have the most "weight" than anything else, so comparing to "640 KiB is enough for everyone", "humans have no means to survive in the vacuum of outer space", "atomic weapons are impossible", "supersonic flights are impossible", "cooling to absolute zero is impossible", "accelerating to c is impossible", the last statement is more likely than other statements.
This is why I believe "no-FTL" argument has a strong point.
But well, I lied... It's well-known that general relativity does not directly forbid one to wrap the spacetime to create worm-holes. So I agree with you, the "no-FTL" has a strong point, but it's a non-issue anyway.
Newtonian mechanics is still very accurate and very useful if it wasn’t it wouldn’t be thought on an undergraduate and even graduate levels, ironically it’s also what we’ve used to figure out things like oh shit were missing a lot of matter in the universe.
If it wasn’t so darn close to being accurate in pretty much every scenario things like MOND wouldn’t have a reason to exist either because for quite a while in fact until the confirmation of gravitational waves there was enough wrong with general relativity to cast doubt on it too, however even with gravitational waves killing most of the modified Newtonian candidates Newtonian mechanics is a darn useful tool still and it’s usefulness would likely never go away.
I don't think we are out of the woods as far as the end of physics development. The 1700's is when scientific thought really started to hit its stride, and we've seen rapid overturning since then. It may take another 200 years for the next overturn, that's unknown but we do know there is one likely in the future due to the limits the standard model to explain all phenomina. To say we've hit the end is a bit of hubris since we're still trying to unify QED and Gravity under some unified theory. We know the standard model is close but wrong, and we will likely still use its analogies in the future just as we do for Newton to simplify concepts. Couple this awareness with the quantum weirdness and the apparent links to consciousness, we may very well be on the threshold of a new level we've barely conceptualized and only caught glimpses of. Newtonian Mechanics expected micro-scopic Newtonian mechanics and got quantum physics instead. Quantum physics expects the same as you get deeper and we may end up with something else completely different underpinning reality, opening up technology we didnt think possible, just like quantum computers, quantum encryption, quantum teleportation, etc. It may not even be FTL in the star trek / star wars sense, just appears to be. Fold space, traverse a dimension then pop out, create an artificial wormhole, who knows.
> The mere existence of a nuclear submarine navigating the ocean in 1800s England, as an object, is compatible with the Newton's Laws of Motion. Although nuclear reaction itself violates other known physics at the time, But if compared to Newton's Laws of Motion, they are not as important. And nowadays, Einstenian mechanics have replaced Newtonian mechanics, and it has the same status as Newtonian mechanics had before.
Isn't this the same with a UFO? Its motion in most cases doesn't necessarily violate physics, at least not all the time, but definitely has some form of exotic technology at its core if it can traverse star systems that we have yet to fully conceive on a functional level (concept vs technical approach). Again, who are we to say Eisenstein Mechanics has no successor? Newton = Sailing Ship. Newton + Quantum = Nuke Sub. Newton + Quantum + (?) = UFO
> That is, among all rational conclusions, those that is directly based on the foundation of mechanics have the most "weight" than anything else, so comparing to "640 KiB is enough for everyone", "humans have no means to survive in the vacuum of outer space", "atomic weapons are impossible", "supersonic flights are impossible", "cooling to absolute zero is impossible", "accelerating to c is impossible", the last statement is more likely than other statements.
> This is why I believe "no-FTL" argument has a strong point.
> But well, I lied... It's well-known that general relativity does not directly forbid one to wrap the spacetime to create worm-holes. So I agree with you, the "no-FTL" has a strong point, but it's a non-issue anyway.
Agreed, a strong point in so much as its the most recent and has the foundation of our current understanding of physics to sit on victoriously, while a little bird named CERN wispers "your victory is false". But as you said yourself, not explicitly forbidden. Nor even outside the realm of technically feasible:
https://www.space.com/17628-warp-drive-possible-interstellar...
Especially if we can find a source of exotic particles:
https://www.space.com/25709-dark-matter-hunt-exotic-particle...
We know there is plenty that we don't know. However, what is so devestatingly sad is that it seems pretty clear that no one living today will ever get a full understanding. Physics progressed pretty quickly in the early 20th century, but it's now moving at a glacial pace. If faster than light travel, wormholes, or multiple universes are real possibilities, it may very well take several thousand years for humans to decipher them.
Extraterrestrial doesn't make sense, because of the difficulty in crossing interstellar distances. But in the case of really solid evidence, eg the Nimitz incident, neither of the first two categories really make sense either.
I think there's a fourth category that people aren't considering: Von Neumann probes which self-replicated in-situ and are performing scouting / intelligence gathering. When people consider Von Neumann probes independently, there's always the question of, why don't we see any around? Given even modest rates of travel and self replication, they should be at every star system in the galaxy, if any were ever created.
Well, maybe they are around, and we have seen them.