How can a state of the art airliner disappear!!!

Its been four days now since MH 370 has gone off the radar and still no trace of the airliner yet. The airliner involved is a state of the art Boeing 777-200 with an impeccable safety record for almost two decades. This airliner has almost everything that technology has to offer in terms of ergonomics, safety and passenger comfort. Thus, it is very disheartening to see such an aeroplane just vanishing off the sky.
           As per media reports, the plane was on course after take-off from Kaula Lampur till it disappeared near the Vietnamese coast, one hour into the flight. No distress call by the crew, no indication from the on- board systems (like Aircraft Communication Addressing and Reporting System) of any system malfunction. Its just gone!!!

Now, what might have happened to this aircraft is subject of speculation until some concrete evidence is found. However, here I would like to discuss certain scenarios that would not have made the aircraft go off the radar suddenly and lose all communication

Scenario 1: Dual engine failure bringing the plane down- Highly unlikely. This aircraft is equipped with two GE turbo fan engines that are highly reliable and have been in service for 20 long years without any malfunctions. Even if both the engines fail, the airplane can glide providing ample time to the crew for making a MAYDAY call. In such an event the radar controllers would also have been able to see the aircraft losing height on their radar scope.

Scenario 2: Total electrical failure leading to a crash: Boeing 777s are equipped with multiple layers of redundancy when it comes to electrical power. Even if the engine driven generators fail, the aircraft has an Auxiliary Power Unit (APU), batteries and the last resort, a Ram Air Turbine (RAT). Even if it is assumed that the APU and batteries failed, RAT ( a fan which can be exposed into the air stream to generate electricity- very similar to a windmill) can still deliver electrical power to essential systems providing ample opportunity for the pilots to make a MAYDAY call. In this case also the radar controllers would have noticed the plane going down on their radar screens. 

Scenario 3: Even in the case of hijack, the pilots would have alerted the controllers and  any anomaly in the flight path would have been detected at the radar station. 

Some possibilities that can explain the sudden disappearance

Scenario 1:  Collision with another flying object: A similar incident happened few years ago in the skies over Brazil. An Embraer business jet flew into a Boeing 737-800 and severed one of its wings. At that time also the 737 had suddenly disappeared from the radar and it was noticed by the controllers only after the crew failed to contact the next radar station. During that accident, the crew did not get time to issue a distress signal.  Before the crash air traffic controller had problems communicating with the Embraer crew due to disturbance on the communication channel. Even in this case the pilots did not issue a distress signal and another Malaysian Airlines pilot who was  flying in the vicinity has claimed to have established contact with MH 370 (on request of ATC) but could not get a response due to disturbance over the communication channel.

Scenario 2:  A massive decompression or explosion resulting in the total disintegration of the structure in to small pieces which did not have sufficient radar cross section so that they could be detected via radar.