Negative gravity, if it were to exist, would indeed have a significant impact on the perception of time. However, the effect would not be the exact opposite of time dilation caused by gravity.
In general relativity, gravity affects the flow of time. In the presence of a strong gravitational field, time dilation occurs, which means that time runs slower relative to an observer located in a weaker gravitational field. This effect has been observed near massive objects like black holes.
If negative gravity existed, it would create a repulsive force, pushing objects away instead of pulling them in. In this scenario, the perception of time would still be affected, but not in the same way as with regular gravity. Negative gravity would cause an acceleration away from the source of the negative gravitational field.
As an object accelerates due to negative gravity, time dilation would occur, similar to what happens when an object accelerates in the presence of regular gravity. According to the theory of relativity, as an object accelerates, time appears to run slower for that object compared to a stationary observer. This effect is known as time dilation due to acceleration.
So, if negative gravity existed and caused an object to accelerate away, the object's perception of time would slow down compared to an outside observer. What feels like hours to the object experiencing negative gravity would indeed appear to be shorter, possibly only seconds, to an outside observer in a different reference frame.
It's important to note that the concept of negative gravity is purely hypothetical, and there is currently no empirical evidence supporting its existence. This explanation is based on the principles of general relativity and time dilation due to acceleration.