We know that there's a connection between the emergence of life and *energy*. And some have speculated that energy is the cause that life emerges.
I don't think that energy is the cause, it's a necessary condition. But here is what I realized: It is very useful to ask what *limits* the amount of energy in an environment that sustains life. Are there upper and lower limits, and if so - what is the reason for those?
OK so the lower limit is easy when we think of the extreme of 0 Kelvin (absolute no movement). Obviously if there is no movement, there can be no life, because nothing can replicate, nothing new can get created.
How about the upper limit? Well, we know that living things (at least as we know them on earth), get scorched by fire or by the sun. However, we also see that different living things can handle different levels and types of energy depending on the environment in which they develop. Deep sea creatures can withstand high pressure, and land creatures have better tolerance for UV light than underground dwellers. In fact, we NEED a certain amount of light energy in order to exist. Too much energy from the sun and we burn up.
If you expose a living thing to more energy than it can process while maintaining its shape, it breaks down. And so life is a thing that organizes itself around being able to absorb the energy in its environment in order to create and re-create its physical composition.
So in theory, if there were a combination of self replicating molecules that could use an intense amount of energy to create more of their molecular structure - we could have life that exists in higher energy environment. However, when we reach a point where the energy causes covalent bonds to break, then no molecule formation is even possible. And that would be a theoretical upper limit.
Also, there may not BE that many combinations for the basic building blocks that answer all the criteria that life requires to originate. And if RNA/ DNA are the only possibility (along with the variety of proteins and other structures that they generate), then it would be their specific properties that determine the upper limit on energy that can sustain life.
So, energy is a necessary component for the phenomenon of life, but it is not its cause.
Oh, one more thing: Energy fluctuation is not good for living things, because we evolve to optimally process a specific set of conditions. When you start to "rock the boat" too much (making it too cold or too hot, too much external pressure or not enough), then things begin to fall apart. Not because life under those conditions is not possible, but because this specific living thing has not evolved in that environment.
