I think the point I was trying to make was missed. I wasn't defending the idea that the Earth is flat or that Man could fly without external means.
I was just using examples of how past scientists and intelligent men have gotten things wrong.
Throughout world history, scientists have gotten most things right, but many things wrong. That was one of my points. Be careful saying something is impossible. Even now some are contemplating that Einstein might have gotten some things wrong.
You said that laws of physics forbid a Star Wars lightsaber aka plasma sword due to the small handle not being large enough to contain the power source. I was pointing out that Traveller breaks the laws of physics also by allowing the light speed limit to be broken.
So let's get into speculation, which is what most of this is. A proponent of Traveller being hard science could state that a jump drive is not breaking the speed of light, but warping time/space. So, the laws of physics are bypassed.
I could imagine solutions to the lightsaber power source problem also. Perhaps the power source isn't in the handle at all, the handle is just a receptor for the vast power that is generated elsewhere. Futuristic solar panels if you will. Power is generated somewhere else, perhaps even naturally, such as a nearby star or planet's core. The lightsaber doesn't contain the power source, just a receptor which collects the energy. So, likewise another law of physics is bypassed.
I'm not saying at all this is what Star Wars intended with the light saber, (George Lucas didn't seem to care much about science) just that certain things that seem impossible by the laws of science at first can find a way to come to reality. Future scientists have invented many things that past scientists claimed were impossible. Let's don't get over-elitist and claim we 'modern' men know all the answers. A few of our modern scientific laws that we somehow got wrong might be laughed at by future scientists who consider us barbarians.
We laugh at the learned scientists of the past who claimed the Sun rotated around the Earth.
[Edited to add some information and lighten the original post]