Ought to have been an observable trail of superheated ionized gas? Why? Because you don't know how to accelerate an aircraft to ultra high speeds without a sonic boom or leaving ionized gas behind? And just randomly thinking, if the hull is cooled with an ultra cold fluid like liquid nitrogen it would reduce the heat signature significantly of any vehicle traveling at a high rate of speed and allow one to possibly eliminate any issue with the air heating up to a significant temperature. And voila it's actually being worked on it's called Liquid film cooling for hypersonic aircraft: https://aip.scitation.org/doi/... Also the US and Russia experimented with using plasma on the hull of their aircraft to eliminate sonic booms but couldn't make it work. A civilization that can travel between the stars would find such a problem to be trivial to solve without needing to leave superheated ionized gas trailing their aircraft.

When was it determined that there's no intelligent life around Alpha Centauri? We don't have telescopes that can determine that in anyway shape of form. And no probes have been sent there to determine such a thing.

The distance argument is only persuasive from the perspective of a primitive civilization like our own with no understanding of technological progress. Because from the perspective of a technological civilization that's been around for thousands of years, crossing interstellar distances may be as trivial to them as crossing the oceans is to us. Moreover it should be understood that one must not take their own limitations to be similar to the limitations of others. That's a logical fallacy.

Actually we do have sharp footage but the video quality is irrelevant to the acceptance of the existence of some UFO's as possibly being ET Craft. Because the pathological skeptics will never have enough evidence short of an alien press conference, which is laughable, and the accepters of the already voluminous evidence don't need anymore evidence.

Billions of dollars have been squandered, decades wasted, careers devoted to a cause that even if successful would not be much better than nuclear fission, as radioactivity is generated in harmful amounts given the fuels used: Deuterium and Tritium. The only logical alternative is the Plasma Focus, a device that works with plasma, rather than attempting to control it via brute force techniques (i.e., intense magnetic fields or laser beams) and uses Hydrogen-Boron for fuel, and can generate electricity safely and directly without the need for power generation using steam and turbines.

There has been much progress with the plasma focus fairly recently. Taken from the Focus Fusion website:

In recently completed test experiments, the researchers were able to achieve temperatures that reached up to two billion degrees in some shots of the plasma focus device, well surpassing previous records of 520 million degrees achieved by the commonly used tokamak device. The much larger and more expensive tokamak has been cornerstone of the US fusion program for 25 years.

The plasma focus functions in a fundamentally different way from other fusion devices. Tokamaks and most other fusion devices use powerful magnets to attempt to stabilize the plasma - the extremely hot, electrically conducting gas in which the fusion reactions occur. This task has been likened to lifting gelatin with rubber bands. Instead, the plasma focus takes advantage of the natural instabilities of the plasma, so that the plasma's own magnetic fields compress it and heat it. "The plasma focus works with the plasma, not against it," says Lerner.

Perhaps someone with the foresight to see the best path for future power generation can fund this research fully and cease our pseudo problems concerning concerns about future energy sources. The solution is apparent.