I stand shoulder to shoulder with a group of people, we all face the same direction. We all have synchronized watches and nobody is moving. We face a second group of people, facing us. They all have synchronized watches and nobody is moving. Now suppose that my group feels like they are in a gravitational field that runs along the group from left to right. Pretend somehow the other group does not. Given that the only difference between the two groups is the presence of a gravitational field for one group, how will their watches compare?