It’s a commonplace in Sci Fi, particularly movies and TV, that spacecraft have shields. What exactly these shields are is never explained - they’re invisible, and often prone to failure. When did this start?
They propably appeared earlier, but I suspect Star Trek popularized them.
I saw this discussed recently on another forum. The earliest example of ships with shields they came up with was from E.E. “Doc” Smith of Lensmen & Skylark fame, from the 1930s. The earliest example of a “shield” they could find was from a 1912 novel called The Night Land, although that wasn’t around a ship.
On Forbidden Planet, while the ship was grounded, the crew set up an energy fence to protect it from ground bound intruders.
Similar concept, if not as portable.
Force field - Wikipedia mentions Der Trihs’ book, as well.
Seconding Trihs, I think they were popularized by “Doc” Smith. Both the Skylark series and the Lensman series are rife with shields, both ship sized and personal.
It drives me crazy when they’re in space battles, somebody take a hit, and then orders “all power to front deflector shields,” or something like that.
- They are obviously not putting all the ship’s power into their shields, because all kinds of other systems continue to operate. Yet,
- If they just mean all available power, why weren’t the shields already receiving that? They’re in a space battle!
Um, because it was evenly distributed around the ship until they had, ya know, a reason to concentrate it? If you had the technology why wouldn’t you built a system that could be adaptable to changing conditions?
I noticed in a lot of sci fi (particularly Star Trek) shields seem to function much like batteries- they have a ‘capacity’ that gets depleted through damage. So ordering maximum power to foward shields would be diverting as much energy toward keeping that arc at maximum power as much as possibly, instead of trying to do so in every direction.
Ordering all [available] power to front shields probably also diminishes the amount of power available for offensive weapons systems.
Duh. 
I’m saying, given such a system, and given that they were in battle, shouldn’t they already be putting all available power (less propulsion, life support, own weapons systems, whatever) to shields?
Reasonable concept, though I don’t recall that ever being a stated factor. I think the Enterprise, etc., blazed away equally (sometimes in-) effectively before and after.
I think you missed my point, I meant that the shield energy was evenly distributed. Since you don’t always know where the attack is coming from, I would probably have that as the default setting, concentrating it by command as a response to damage or a focused attack.
I could also see a short term overide that would cut power to some systems like life support briefly, like afterburner.
Always assuming a lot of parameters that seem to be for dramatic purposes actually turned to to apply to the physics of shields. 
Most shields are hooked directly into the plot device, which can override any system.
Of course, the idea of the main protection for the vessel being some sort of force-field is sensible in the context, as it frees you from having to have your spaceship massively armored; of course, this is all based upon the usual Pulp-SF presumption of a preposterous power-ratio in whatever’s your energy source (up until the plot requires you to run out of power at [in]convenient times, of course…).
As to shield degradation, besides being dramatically useful it injects an element of conservation of energy – the shield-field absorbs/redirects the radiant or kinetic energy of the incoming. Once you exceed the capacity to store/redissipate that energy quickly, the shield system becomes less effective, and if outright overloaded it just goes down.
In Star Trek Online, when a single ship attacks you, they can only attack one side at a time. They have to wear out the shield on that side. When your forward shields start to get weak, you can redistribute power from the other shields to compensate. When you move all available power to the front shields, you weaken or almost remove the rear shield. I think the shields also wear out faster if your ship is going faster. I’m not positive about that, but it seems like the shields are a lot stronger when I’m going half impulse instead of faster. If that’s true, it means engines and shields draw from the same power source and you have to choose what is more important at that time.
Well yes, that’s usually a given.
Der Trihs seems to have come up with the earliest example - and after only 10 mins! I love the Dope!
That said, I find the concept of shields a bit off. One of the things I liked about BSG - in either incarnation - was that there were no magical shields.
But really, if you accept the speeds that they travel at, some sort of shielding is a given. Even a dust mote could be deadly at Warp 3. The Enterprise always has “navigational shields” deployed at the very least.
In Arthur C. Clarke’s Songs of Distant Earth the ships moving at relativistic speeds used “shields” made of ice to intercept interstellar matter. Magical shields aren’t required.
I saw this too late to jump in, as others had already made the suggestion of E.E. Smith, who first came to mind. I hadn’t heard of The Night Land, although it’s in the Wikipedia entry on force fields. I woulda thought that Edmund Hamilton (who popularized and often invented many SF concepts) would be a major user of these, but from what I see, he only started using them after they had already been established. Certainly by the 1940s Force Fields were part of the common stock of SF props. Star Trek was the first place I recall hearing ship-protecting force fields called “shields”, and I’m sure they did more to introduce the concept to the wider public than anything else. Before that, space battles in movies* consisted of ships shooting and dodging
*This Island Earth, for instance. Or the Phantom Planet.
I’ve been using my personal shield since before the 2nd Dexitroboper Dynasty…
I guess the Romulans can’t invent a torpedo or something that goes around and attacks the Enterprise from the other side at the same time.
Yeah, and you would think that they would be quicker to put up shields in the first place. You would think they would authorize the the bridge crew to go ahead and raise shields if, say, a Borg cube appears, instead of waiting for the captain to say “shields up.” Or they would program the computer to do it.