[Calvin Locke]

However, that clock would need to be traveling at speeds approaching that of light in order for the effects to be noticeable.

Nah.

IIRC, FWIW, in the 1960s, the US Navy took two matched Cesium clocks, and put one aloft on a plane for some period of time.

Eventually, the clocks were brought back together, and the one with flight time was behind the one that stayed on the ground.

I think a MIT student, also in the 1960s came up with a theory to travel back in time, but hit the "infinite mass" issue as well.

[ETL]

"However, that clock would need to be traveling at speeds approaching that of light in order for the effects to be noticeable."

Nah. IIRC, FWIW, in the 1960s, the US Navy took two matched Cesium clocks, and put one aloft on a plane for some period of time. Eventually, the clocks were brought back together, and the one with flight time was behind the one that stayed on the ground.

I meant noticeable to us, without relying on an atomic/cesium clock. As for the airplane experiment, see my post 38. And also 41, regarding the GPS satellite network and Relativity.