3.2 Summary

summary

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Some organisms contain information to pattern their entire bodies. For example, planaria are flatworms that can be cut in half and can regenerate their entire structure. Somehow, stored in the organism is the information to pattern the missing pieces. The organism can also be reprogrammed to have two heads or two tails.
Information in the human body is constantly and actively helping to reconstruct our physical self. Almost every atom in a human’s body has been replaced over the past ten years.
The “laws of life” might be laws of information. For example, to understand the laws of gravity, black holes can offer insights as extreme examples of gravity. Similarly, if we want to understand information, we study living entities because they are densest with information. Life is a property that enables us to measure how much information there is. There is no firmly defined line between there being enough or not enough information for something to constitute life.
“Life-like” behavior with complex chemistry can also be illuminating, such as in systems of oil droplets. Swarming, for example, is a property that can emerge in chemical systems that is also seen in living systems like flocks of birds.
Machine learning is a new technology being applied to understand life and look for new predictive frameworks.
Most of our efforts are to look for life on Earth-like worlds, but we don’t know whether Earth is a common planet, or whether we are common in terms of the properties of life that we exhibit.
In comparing Earth to other planets, such as Mars and Venus, it turns out that the network structure defining Earth’s atmosphere looks more like the network structure for the cells on Earth than it does for the atmospheres of Mars and Venus. Earth’s atmosphere looks more like a living network. This representation might help uncover different structures on other potentially living planets. The key is that our planet has oxygen in the atmosphere.
We can also look for life statistically and pose two broad questions: What is the likelihood of life? How much of the universe is life?