If someone asked me to describe the universe in one word, I would call it expansive. Expansion is the fundamental driving force behind everything that happens, from the simple life of an amoeba to the sun burning bright in the sky.
You can observe expansion in action when you breath out on a cold day, and see a white cloud spread out and fade. Simply put, everything that exists wants to spread out evenly unless something stops that from happening.
The Currency of Life
That something that resists this endless force is energy. Energy is the most valuable currency for any complex structure. In the case of planets holding themselves together, this is gravitational potential energy, in the case of life, it is ATP and thermal energy. Essentially, the use of energy is the only way to reorganize atoms in one’s surroundings. Energy must be spent whether a cell is trying to copy DNA or a person is walking from point A to point B.
The Most Important Forms of Energy
The two main sources of biological energy are chemical potential energy (ATP) and thermal energy (heat).
What is Chemical Energy?
Chemical potential energy is relatively easy to explain: in order to create and use organized molecules (proteins), energy must be added to the system. This type of energy is present in all organisms. Proteins will be discussed in a future post.
What is Thermal Energy?
Thermal energy is slightly less intuitive but equally important. Complex molecules need to be kept at a certain temperature to maintain their structure and function (future post) . To understand this, imagine a guitar string as a molecule; the harder you pluck the string, the stronger the vibration. At a certain point, the vibration will be too strong and the string will snap. The vibration can also be too weak resulting in no sound.
These analogies are almost exactly what happens. At high thermal energy, the bonds between atoms begins to break down (remember, biological energy is the driving force of change). Due to molecular collisions, the molecule loses its function. At low thermal energy, the bonds between atoms either become too rigid or find a less complex, more stable form which results in the loss of function.
Take us humans for example. Through evolution, we have developed many systems dedicated to keeping us together and resisting this endless force. Of course, our skeletal system holds us together but the laws of the universe works on things at every scale.