For those who have been disappointed by the lack of excitement in technological advancements take a look at this.

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An open mind is like an open window...without a good screen you'll get all sorts of weird bugs!

Stuart's not going to like this. And I thought that space elevators were damn exciting.

Hmmm...plasma TV...

What? D'oh!

Plasma shields: could work, but you'd need an energy source. And I don't think they'd afford much protection against missiles.

Laser weapons: could work, but require either fuel or an energy source. Hydrogen fluoride lasers could do a real number on aircraft, but would be quite impractical as anything but spaceborn or immobile ground-based weapons. (And spaceborn weapons go against international law, IIRC.)

Overall, I think it's currently a bit impractical.

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If ignorance is bliss, why is the world so full of misery?

When considering particle beams and lasers as weapons, people don't always consider their main benefit: the haywire effect. A high-energy particle weapon or an electron laser could disable the electronics on an aircraft even with a glancing hit. It need not cut the fuselage to shreds or blast through an engine. The cold plasma technology proposed on the link would counteract weapons of this sort.

I still don't approve of focusing on warlike applications of any technology that could be used for medicine and space exploration instead.

Only space-based nuclear weapons are prohibited by various treaties. Laser & other weapons(like that 23mm cannon the Soviets put on the Salyut Space space station back in the '70s.) are perfectly legal.

As for laser weapons, there is the Anti-ballistic missle laser, which is being tested inside of a modified 747, and there is the Tactical High Energy Laser, which is designed to shoot down rockets and artillery shells, which is also being tested at the moment.

Using simplifying assumptions, could they even hit the Earth with it?

That's what makes a PA28 superior to a Tornado. You can still fly it very proficiently if with one of those laser hits. You just wouldn't be able to tell anyone about it. #-o

Why are you guys talking weapons? This is primarily a defensive thing and potentially a sterilizing device.

If you want a good offensive weapon, strap a small nuke to a good air-to-air missile modified with directional control thrusters and an upgraded guidance system.

And no plasma defence will stop it.

What, exactly, would be the purpose of putting a 23 mm cannon on a space station? Wouldn't the recoil move the thing?

The purpose was to be able to defend against any attacking American spacecraft. And it had thrusters designed to fire and balance out the recoil whenever the cannon was used.

Ooo... thats cool... I want a space-based cannon. *bees jelous* :P