The Earth is Unimaginably Vast
For those who are frustrated at the apparent inability of modern technology to find a large passenger jet even after days of searching it may help to consider the following.
The total surface of the earth covers around 510 million square kilometres.
Water covers 361 million square kilometres and land 149 million square kilometres.
Assuming that a 777 jet (or wreckage) covered an area of 50 by 50 metres (a large over estimate), then that still only represents 1/400th of a square kilometre.
Given that the theoretical range of the jet covered nearly a third of the earth's surface (call it 150 million square kilometres), investigators are looking for a single point measuring at best 50 metres by 50 metres in all of that area. So 150 million square kilometres times 400 = 1 point in 1,600,000,000 possibilities at best. That is assuming the aircraft or wreckage are visible from the air. If it is under water or has made a smaller impact crater on land, the odds become even greater against locating anything.
Obviously the investigators are doing everything in their power to try and reduce the odds by calculating the most likely flight path, but the search is going to take a long time.
Yes, we can fly around the world by jet in under two days, or in 90 minutes with a spacecraft in low earth orbit. But the earth is still unimaginarily huge, despite the wide angle shots from ISS and the blue pebble photo taken from the moon (also with a wide angle lens).