Elon Musk: I don't see any evidence of aliens.

Its a solid argument if you are willing to use our current understanding of reality as a constraint.

At any point in our history you could use such a constraint to come up with a "logical" argument against some phenomenon. However, if our history has taught us anything its that we should be quite cautious about using such constraints.

Take Miasma Theory (MT) for example.  Put forth in the 4th century BC by Hippocrates it was generally accepted for over 1,000 years as a theory of disease. While not a perfect analogy because we now know how misunderstood this was based on more modern disease theory, at the time folks like you and me would not have known any better.  It would have been perfectly logical to reject theoretical phenomenon that conflicted with MT just a few hundred years ago.

So, for me at least, using our current knowledge of cosmological physics to categorically reject even the possibility of interstellar travel just seems hyper arrogant and very likely to be proven wrong over time.  I can't justify the latter part of my last sentence, but history would seem a useful handicapper for it.  Again, imagine telling a learned person in the fourth century BC that we'd have all the tech you see around us today.  They would have been incredulous.

So, for me at least, using our current knowledge of cosmological physics to categorically reject even the possibility of interstellar travel just seems hyper arrogant and very likely to be proven wrong over time.  I can't justify the latter part of my last sentence, but history would seem a useful handicapper for it.  Again, imagine telling a learned person in the fourth century BC that we'd have all the tech you see around us today.  They would have been incredulous.

Yeah I don't think it's a fatal objection, while at the same time I do feel the likelihood of alien craft coming here is low to none.

Largely because there has yet to be, AFAIK, even pictures of the crash materials/corpses. The physics barrier is part of my doubt, but not a major one *if* anything approaching direct evidence was offered.

But I also doubt the "nuts & bolts" theory because the claims of craft largely seem to be from a distance, and when this is not the case you have to include the Weird cases where the aliens seem bizarrely human-like in behavior if not appearance and do bizarre things.

Its a solid argument if you are willing to use our current understanding of reality as a constraint.

At any point in our history you could use such a constraint to come up with a "logical" argument against some phenomenon. However, if our history has taught us anything its that we should be quite cautious about using such constraints.

Take Miasma Theory (MT) for example.  Put forth in the 4th century BC by Hippocrates it was generally accepted for over 1,000 years as a theory of disease. While not a perfect analogy because we now know how misunderstood this was based on more modern disease theory, at the time folks like you and me would not have known any better.  It would have been perfectly logical to reject theoretical phenomenon that conflicted with MT just a few hundred years ago.

So, for me at least, using our current knowledge of cosmological physics to categorically reject even the possibility of interstellar travel just seems hyper arrogant and very likely to be proven wrong over time.  I can't justify the latter part of my last sentence, but history would seem a useful handicapper for it.  Again, imagine telling a learned person in the fourth century BC that we'd have all the tech you see around us today.  They would have been incredulous.

I would, on the contrary, argue that the ancient Greeks got most things right. They figured out the heliocentric model, realized that the Earth is a sphere and not flat, using arguments that go over the heads of most people today, and made quite accurate calculations of the distance to the moon. They also hypothesized about the existence of atoms.

Special relativity is not particularly complicated and can be taught at the high school level. It is utilized in common technical commodities and should not be compared with speculative and unverifiable cosmological theories that attempt to explain everything. Any new undiscovered physics is likely to have as much impact on your daily life as the discovery of the Higgs particle (the last major discovery).

The burden of evidence against the concept is incredible, and we need to weigh this and other arguments against the very little convincing argument that humanity first learned about this through the claims of a single individual who hasn't even personally witnessed any nuts-and-bolts artifacts.

I would, on the contrary, argue that the ancient Greeks got most things right. They figured out the heliocentric model, realized that the Earth is a sphere and not flat, using arguments that go over the heads of most people today, and made quite accurate calculations of the distance to the moon. They also hypothesized about the existence of atoms.

Special relativity is not particularly complicated and can be taught at the high school level. It is utilized in common technical commodities and should not be compared with speculative and unverifiable cosmological theories that attempt to explain everything. Any new undiscovered physics is likely to have as much impact on your daily life as the discovery of the Higgs particle (the last major discovery).

The burden of evidence against the concept is incredible, and we need to weigh this and other arguments against the very little convincing argument that humanity first learned about this through the claims of a single individual who hasn't even personally witnessed any nuts-and-bolts artifacts.

Quite reasonable.  After our back and forth I think we're much closer than a third party might have thought by reading this thread (no surprise to me really; I respect you!).

We're likely just a degree or two off on estimate of the non-zero probability that there's an, as yet not understood, method to travel massive distances.