Intro: As a physicist one of the first important things we learn is the conserved quantities in a system. It is simply any thing that will not change, no matter how the whole system changes. I never thought about it outside my work, but I realized it has always been my benchmark. When you pass the middle age and you realize you have a limited life span, you start thinking about what is eternal? How are we connected to the eternity?

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One of the most satisfying tasks we can spend our lifespan on is to understand the universe we are living in. I study the largest scales of the universe, galaxies. In this scale we deal with billions of years of change and billions of stars. Compared to our short life span and our tiny planet, this is eternity.

I always think about ants for perspective. Nevertheless, we are equipped with more powerful tools to understand the world. It seems to me the most efficient way is to prioritize this sense curiosity and spirit of wonder, but there are so many other mortal goals and persuasions we have to spend our lives on. Sometimes I feel down. More I live, more I realized it is just a giant scam. And other times I get excited to see rays of light shining through cracks.

I think we all understand this urgency. But not many of us put this in our todo list. People don’t forget, they just don’t remember.

At the end this emotional up and down, I always come to this conclusion that it our mortality is a very small fraction of eternal nature. As hydrogen turns to stars, stars combine lighter element and build every other element, these heavier elements become planets, and life as we know emerges on a planet and the cycle of life and death continues.

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