Jerry, help with these questions, inquiring minds want to know.

1, If there was an onboard explosion why wouldn't someone see the debris field or at least a piece of evidence that it came from this 777, if it was over water wouldn't there be debris floating/drifting somewhere?

2, If the flight continued either hi-jacked or ???, why wouldn't it still be seen on someone's radar screen?

Thanks for helping.

Mike