All comparisons between America's current place in the world and anything legitimately called an empire in the past reveal ignorance and confusion about any reasonable meaning of the concept empire, especially the comparison with the Roman Empire. ↗
I can see that you are a true historian because you really always ought to ask that question about anybody at a different place or a different time: What's the same and what's different? ↗
For some years I have spent my time on exactly these questions - both in thinking about ways to prevent war, and in thinking about how to fight, survive, and terminate a war, should it occur. ↗
Experienced happiness refers to your feelings, to how happy you are as you live your life. In contrast, the satisfaction of the remembering self refers to your feelings when you think about your life. ↗