Yes, in addition to relative velocity, there are other factors that can affect the passage of time for two people experiencing different accelerations as they move through space-time. These factors arise from the principles of general relativity, which describe the curvature of space-time in the presence of mass and energy.
Gravitational Time Dilation: According to general relativity, the presence of a gravitational field can cause time to pass at different rates depending on the strength of the field. Clocks in stronger gravitational fields, where the gravitational potential is higher, run slower compared to clocks in weaker gravitational fields. This effect is known as gravitational time dilation. So, if two people are at different distances from a massive object or experiencing different gravitational fields, their clocks will tick at different rates.
Gravitational Redshift: Related to gravitational time dilation, gravitational fields can also cause a phenomenon called gravitational redshift. Light or electromagnetic radiation emitted from a region with a stronger gravitational field will experience a shift to longer wavelengths (redshift) when observed in a region with a weaker gravitational field. This redshift is an indication of time dilation as well.
Gravitational Waves: Gravitational waves, which are ripples in space-time caused by accelerating masses, can also affect the passage of time. As gravitational waves pass through an observer, they can induce stretching and squeezing of space-time, which in turn affects the local flow of time. This effect is typically very small for everyday scenarios but can be significant near powerful gravitational wave sources, such as merging black holes or neutron stars.
It's important to note that these effects become more prominent in extreme conditions, such as near black holes or in regions of strong gravitational fields. For most everyday situations on Earth, the effects of gravitational time dilation and gravitational redshift are negligible and not readily noticeable. However, they play a crucial role in various phenomena, including satellite navigation systems and the behavior of objects near massive astronomical bodies.