Yes, according to Einstein's theory of general relativity, time does indeed appear to go slower when you are in orbit around a massive object. This phenomenon, known as gravitational time dilation, is a consequence of the curvature of spacetime caused by the presence of mass or energy.
To understand the physical explanation behind gravitational time dilation, we need to consider the concept of spacetime curvature. In the presence of a massive object, such as a planet or a star, spacetime becomes curved. This curvature affects the geometry of spacetime itself, causing it to be distorted near the massive object.
In the context of time dilation, the curvature of spacetime near a massive object results in a variation in the gravitational potential. Clocks located at different heights in this gravitational field experience different gravitational potentials. According to general relativity, the flow of time is influenced by the strength of the gravitational field and the curvature of spacetime.
When an object is in a region of stronger gravitational field, such as near a massive planet, the flow of time for that object will appear slower relative to an object in a weaker gravitational field. This means that clocks closer to the massive object will tick more slowly compared to clocks located farther away.
One way to visualize this effect is to consider a scenario where two synchronized clocks are placed at different altitudes in the gravitational field. The clock at the lower altitude, closer to the massive object, will experience a stronger gravitational field and, therefore, will tick more slowly than the clock at the higher altitude.
Gravitational time dilation has been experimentally confirmed through various observations and measurements. For example, experiments using atomic clocks on Earth and satellites in orbit have demonstrated that time runs slightly faster in space than on the surface of the Earth, consistent with the predictions of general relativity.
In summary, the physical explanation behind gravitational time dilation is that the curvature of spacetime caused by a massive object affects the flow of time, causing clocks closer to the object to tick more slowly compared to clocks in weaker gravitational fields. This phenomenon is a consequence of the profound connection between gravity and the geometry of spacetime described by Einstein's theory of general relativity.