It will be possible in the far future. The theory is simple, however, its application is somewhat intricate. Hiding aeroplanes from radar detection a step in its direction. You will find several theories forwarded.
Many people vanish every year without a trace.
I constructed one theory and devoted an entire chapter to it. As long as earthlings cannot prove me wrong, this one and all other theories are valid, even the one in the Holy Bible. Interested people have just discovered how to lift off from this planet. Advanced aliens have done so a long time ago, and developed ways to go anywhere at any time, in an instant or leisurely. To judge by the reception they got on this planet, not much.