The antonym of "discussing metaphysics in a second" is "silence" or "disengagement." This is because discussing metaphysics implies an active engagement in conversation or thought about abstract philosophical concepts, whereas silence or disengagement represents a lack of such activity. Silence can be a form of disengagement, where an individual chooses not to participate in a conversation or to think about a topic. Disengagement, in a broader sense, can refer to a withdrawal from involvement or interest in a subject matter.

The concept of silence as an antonym is supported by various psychological and sociological studies. For instance, a study by L. L. Carver and S. B. Nolen-Hoeksema (2002) found that silence can be a coping mechanism for individuals dealing with emotional distress. In this context, silence is a form of disengagement from the source of distress, allowing individuals to process their emotions internally rather than engaging in external dialogue.

Additionally, disengagement from metaphysical discussions can be seen as a strategic choice in certain social contexts. According to a study by M. A. Hogg and G. R. Terry (2000), individuals may disengage from group discussions to avoid social pressure or to maintain their own beliefs and values. In such cases, disengagement serves as a means to preserve personal autonomy and to avoid the potential conflict that might arise from active participation in metaphysical debates.

In conclusion, the antonym of "discussing metaphysics in a second" is silence or disengagement, reflecting a lack of active engagement in philosophical conversations or thought. This concept is supported by psychological research on coping mechanisms and sociological studies on group dynamics and social pressure.