Because they predict things accurately. That's all there is to it.

Ok name me one of the basic physical laws - like say Ohm's law, the gravity law, the charge law, the gas laws, etc that has been proven incorrect. Like I said - we may not understand things completely. We might have to add on to these laws or fine tune them for special cases. But nothing in physics is getting "re-written", although sometimes it gets written in a completely different language depending on the context. However every new addition must necessarily fit within the context of the old. Otherwise how could it exist in our universe? Yes there are places on the map marked "Here Be Dragonnes", but now we know exactly how those dragons must behave. Multiplication does not invalidate addition.

if you reread my post: "near total vacuum". It's empty enough.

Except solar panels lose power over time. You know, entropy and all that. Plus if you're moving away from the very star powering your craft, well then "forever" is not as long as you'd like.

Modern physics is never incorrect. Although it can be misunderstood at times. In the same way that relativity does NOT disprove Newton it confirms it, but extends it. Who would have thought that a little denominator with square root 1-(v squared / c squared) was missing, especially since if v = 0 then the whole denominator ends up being one...which means that all previous laws are valid exactly as they are. Science is not about great schisms where meanings and understandings are suddenly reversed from one generation to the next. That's politics and religion. Science is about progress, with every additional step necessarily building on the steps that were before it. Of course sometimes when you're standing a few steps higher up you get a better overall view of your surroundings and realize that maybe you were misinterpreting a few things before but now you understand them perfectly... until someone comes and puts another little step under your feet and you can see even further...

Oh you'll slow down alright. Eventually. In a spectacular fireworks display when you slam into some planet/star that got in your way... you probably won't be alive by then though.

Something is going to be generating the electricity to create those microwaves, and THAT is going to require some sort of fuel. There is no free lunch. Perpetual motion does not exist. And ya cannae change tha laws of physacks Jim.

Fixed that for you. Well, for your reader anyway - you probably understand it. Because of the way these things work, they are just about useless anywhere other than a vacuum. The only way you can spend a tiny tiny amount of energy accelerating particles to massive speeds is when there's nothing else in their way for them to bounce off of. But if you are not in any kind of rush for your delta v and are in near total vacuum this is almost a perfect engine.

There is. It's called Muphry's law..

Just under orbital speed, around 7000 metres per second?

Yes this is especially true since they updated Kerbal Space Program manager to 1.02...

Er, today there are far more people still living with their parents than ever. If you want to measure "standard of living" in terms of gadgets go ahead. In the 1950's one man could support his wife and several kids with a house fully paid for, health costs were not a problem, etc. Today? You are a slave to the bank. Don't you or your wife dream of getting sick. Can you afford that baby, and more importantly will mom and dad mind you adding yet another family member into the already crowded house?

And someone needs to go about registering and licensing the drivers, like the law says taxi drivers are supposed to be. Just because you don't "call" it a taxi doesn't mean it's not a taxi. The law already exists and Uber needs to be held accountable.

But do you dislike it enough to pony up for business/first class tickets? No? Then suffer, cattle.

How about illegal worker?