A revolution is going on in this peaceful land of white birches and blue water--one sure to change naval warfare for all time.

Day after day, night after night, earnest young Americans fly out of the Brunswick Naval Air Station in yesterday's planes to learn how to sink ships and submarines with tomorrow's weapons.

They are part of the first wave of U.S. air squadrons armed with the type of "smart" anti-ship missiles that came close to turning the tide of battle in the Falkland Islands.

"It's a new world for us. It gives us a pretty exciting new dimension," said Rear Adm. Edward A. Wilkinson Jr. in discussing his outfit's mission to learn how to sink ships with the American counterpart of the French Exocet, the missile the Argentines used with such devastating effect against the British fleet off the Falklands.

Wilkinson commands the 12 squadrons of Lockheed P3C Orion propeller planes that, until recently, were limited mainly to lumbering back and forth over the Atlantic searching for Soviet submarines. Now those innocent-looking P3Cs are practicing how to find and sink surface ships with a weapon called Harpoon, a self-guided missile with a 60-mile reach, longer than Exocet's.

In one sense, the P3C-Harpoon combination epitomizes the "dumb platform-smart missile" concept: once the enemy ship is found, about all the men inside the P3C have to do is launch one of the Harpoons toward it and let the missile do the rest.

The Harpoon is designed to fly itself, homing in on radar beams that it bounces off the target ship. It flies low over the waves to make it hard to hit, zooms up high when it reaches the ship and drives a 500-pound warhead smack into the ship's vulnerable top decks.

But the key to winning sea battles with such revolutionary tactics and weapons is finding and identifying enemy ships hiding on the vast, gray expanses of the world's oceans.

Big planes like the four-engined Navy P3C and Air Force AWACS (Airborne Warning and Control System), militarized versions respectively of the Lockheed Electra and Boeing 707 passenger liners, are best for this because they can carry so much and fly so far.

The P3Cs based here, for example, normally go hunting with a crew of 10 to work the tons of electronic gadgetry designed to win the life-and-death Atari games against ships and subs.

It takes a special breed of soldier, sailor, airman and Marine to play this game well during missions lasting 12 hours or more. These men are dramatically different from the swashbuckling fighter jocks who jump off the page of Tom Wolfe's book, "The Right Stuff."

Some of the characteristics of this new breed show up in such mundane places as P3C squadron parking lots and offices. Here, outside P3C squadron VP44, the parking lot features sedate sedans and pickup trucks rather than the racy Corvettes, Datsun ZXs and MGs that dot fighter jock country. And the symbol of VP44 is the harmless pelican, in contrast to the fighter squadrons' hawk, tiger or leopard.

The men who find the ships and submarines have the quiet seriousness of accountants and engineers.

Seven of them sit in the back end of a P3C, staring hour after hour at radar scopes. They study magnetic field readouts to find the telltale metallic disturbances caused by ships and submarines, listen intently to the ocean sounds sent up from undersea microphones dropped into the water by the P3C, triangulate the foreign sounds of submarines and ships to figure out where they are and which way they are going and watch for radio signals emitted from ships and submarines and plot them.

They speak the language of computers, and punch a seemingly endless assortment of buttons to keep the computer working on the problem of finding that enemy ship, and, in a war, sinking it.

Back on the ground, come Miller time, these electronic hunters on the P3Cs, both officers and enlisted, are more likely to go home to wives in the suburbs than hit the Officer's Club to tell tall tales or roar around waterfront bars, if the locals tell it true.

Why would any young naval officer settle for doing such tedious work cooped up in the back of an airplane, spending a third of his time away from home flying from distant air strips in the Azores, Bermuda, Iceland, Italy and Spain?

"The challenge and responsibility you get at an early age," answered Lt. Harry B. Harris Jr., 25, whose job as tactical coordinator of a P3C is to coordinate the work of the men and their millions of dollars in equipment in the back of the plane.

Harris, a Naval Academy graduate, makes about $30,000 a year, counting everything, and said he is developing "a saleable skill in management and leadership" should he decide to seek civilian employment.

Lt. David S. Elliott, 26, a commander of a P3C in Squadron VP44 and also a Naval Academy graduate, said he has enjoyed flying the plane but now wants to get into the personnel business to get a bigger view of the Navy. No desire burns in him or other P3C pilots interviewed to get into a hot fighter like the Navy F14 and land on aircraft carriers at night.

One big disadvantage of that life in the eyes of this new breed of technocrat gaining ascendancy in all the military services is being confined to a ship in the middle of the ocean for up to six months at a time, away from wives, children and friends on shore.

"On a ship you'd be away from everything all the time," said Warren J. Schick, 20, an enlisted technician manning one of the P3Cs consoles. "This has got to be better than that."

In a war, said Jack Reid, 21, another enlisted technician explaining the lure of P3C hunter planes, "what goes up comes back down, but what goes down doesn't come back up."

Besides, he continued, "I'm not 22 years old yet, and I've been around the world already."

As his P3C went into a search pattern over the Atlantic on a practice mission the other day, Harris took over the gadgetry for launching the Harpoon ship-killing missile. Since each Harpoon costs $775,000, the missile was not actually launched but electronically simulated.

The simulated launch looked little more difficult than adding up a grocery bill on a hand-held calculator. Harris spun tumblers on the display board before him until they showed the number of miles to the target ship, the altitude of the plane, its heading and that of the ship.

The firing pin was a prosaic round button inside a round, red ring the size of a half-dollar. Pushing it in a war would sink a ship costing 1,000 times more than the Harpoon missile, if all went as advertised. The ratio of the cost of a Nimitz nuclear aircraft carrier, costing $3.4 billion, to Harpoon missile, costing $775,000, is more than 4,000 to 1.

The cost ratios pose a tough question to military planners: if comparatively cheap Exocet and Harpoon anti-ship missiles are so effective--as they have shown in test firings and off the Falklands--why keep spending billions of dollars on surface ships?

At the top of the U.S. Navy, the argument is that the Exocet or any other cruise missile in reach could not do to American ships what it did to British ones.

Navy officials contend that the long reaches of the carrier-based F14 fighters and their Phoenix missiles would knock the launching plane out of the sky before its anti-ship missiles could be launched. And if such a missile slipped through the F14-Phoenix net, Navy ships have--or soon will have--defensive missiles and Gatling guns.

So, full speed ahead with the 600-ship Navy recommended by President Reagan and long sought by the admirals.

But this is far from the unanimous view in other reaches of the Pentagon, in Congress and in the aerospace industry, where specialists shake their heads in puzzlement as they try to figure out how to keep a surface ship from being sunk by barrages of smart missiles like Exocet and Harpoon.

Once harnessed to the required electronic gadgetry, these anti-ship missiles can be launched not only from big planes like the Navy P3C and the Soviet Backfire bomber, but from submarines and surface ships as well.

So the surface ships in any next war must be prepared for smart missile attacks from above, under and on the sea. An argument can be made that the odds have shifted sharply to the offense.

Navy assurances aside, Defense Secretary Caspar W. Weinberger, like Harold Brown before him, wants to exploit this revolution in naval weaponry as well as try to defend ships against it. Weinberger, in his latest guidance to the armed services, orders the Air Force as well as the Navy to gear up for sinking ships with Harpoons and anti-ship missiles with an even longer reach.

Admirals and generals at the moment are dancing a minuet as they try to exploit the anti-ship missiles without stepping on each other's toes. Under one plan in the works, Air Force B52s would get the Harpoon as soon as the B1 bomber becomes available. To some specialists, C130 transport planes look like good anti-ship missile launchers as well. Policy fights over who should do what loom large on the horizon.

But there is another big question hanging over this revolution in weaponry: would an American president allow a future Lt. Harris sitting at a P3C console push the launching button without seeing with his own eyes the ship about to be blown up?

The radar and infrared eyes of a P3C can see much farther than human ones; the Harpoon can find and sink a ship out of eyeball range as well. Should Harris be allowed to push the button on the basis of what his consoles alone tell him?

In Vietnam, the answer for American fighter pilots was no. They had to fly past and identify an enemy plane with their own eyes before shooting at it. They could not exploit surprise by firing a missile at a plane detected by radar and visible only on the cockpit scope. Critics of the Vietnam directive contend that it does no good to buy Harpoons and other anti-ship cruise missiles that can shoot farther than the eye can see if mechanical identification is not good enough.

Defense leaders, both civilian and military, know they are smack up against this question. A drive is under way within the Navy to equip P3C planes here and elsewhere with advanced identification equipment so they can pick out and identify with a higher degree of certainty the enemy ships without seeing them first with human eyes. Navy Secretary John F. Lehman Jr., for example, said he would rather buy these new mechanical eyes for existing P3Cs than purchase more airframes from the builder, Lockheed.

P3Cs here and Navy A6 attack planes elsewhere equipped to launch Harpoon anti-ship missiles are testimonials to the revolution in naval warfare here. The question for the policy makers, then, is not whether there is such a revolution but how best to handle it.

Former defense secretary Brown, asked toward the end of his term what worried him most in the future of conventional warfare, replied: "I just don't know how I could keep surface ships afloat against cruise missiles in a war."

And that was before the Falklands. CAPTION: Picture 1, Tucked under plane's wing is a training model of the Harpoon missile. The combat version is self-guided and had a range of 60 miles. Each Harpoon costs about $775,000.; Picture 2, Rear Adm. Wilkinson: Anti-ship missiles give Navy "a pretty exciting new dimension."; Picture 3, Petty officer John Wierzbicki at work inside a Lockheed P3C Orion propeller plane. U.S. Navy photos