To measure something we do not know with something we think we know. To be exact is difficult. It demands effort and knowing of facts, knowledge over the world, how it is and how we are in it. Such knowledge which is not measured by eyesight and thinking you know takes time to find out and look for. To know how the world and nature work is a very basic method of learning to see connections, links between happenings, reactions and outcomes, comparisons and dimensions. Why something happens as it does and how patterns evolve and appear in front of us, in us and without us. We often like to know how big something is and are astounded by vastness, grandness and miraculous infinite nature of what is, for instance heart of a blue whale, temperature of volcanic lava, suddenness and randomness of nature and how close can we get, yet the very accuracy and beauty of it and danger: distance to Mars and could it be inhabitable. We would like to know and do because we can and cannot. We are curious to the limits and beyond. Whether something could be done just because we can test it and try out, experiment with any cost entails also the question of what should be left undone. Imagining diving inside a blue whale in its veins, imagining being eaten by a whale and ending up in its stomach and staying alive, getting out when it washes out to the shore. Where would we have gone without that experiment? What is unimaginable becomes reality, an adventure, survival, living, breathing, to think how many cars should be put in line to measure the Earth to know its circumference. To measure something which size we cannot comprehend unless we measure it with something we can see and we know, comprehend in everyday life, size of ours.