The conditions in some parts of the universe are constantly changing. (We live in such a part.)

On the largest timescales, the universe is rolling down an entropy gradient, constantly moving towards a state of maximum disorder according to the principles of thermodynamics.

Stars are born in stellar nurseries, incorporating the elements forged in the hearts of older stars. The protoplanetary disk radially differentiates according to mass and thermal properties, creating a variety of planets and moons with different compositions, climates, and possibilities for life. The star changes slowly for some time, and the conditions on planets nearest it change gradually with it, until it reaches the end of its lifetime and changes more quickly.

Meanwhile, the planets form. On the largest timescale, as the planets cool, they are for some time hot enough to be tectonically active, allowing for the recycling of crustal materials and the potential for a dynamic, shifting landscape. These processes shape the planet’s surface over millions of years, creating mountains, canyons, and other features. The planets orbit the star, forming oscillations which can cause periods of different temperatures, solar illumination, etc.

The nature of the activity in a tectonically active planet results in punctuated equilibrium, with periods of rapid change followed by periods of relative stability. Volcanic eruptions can drastically change the atmosphere and climate in short periods of time, changing the range of conditions on the planet. (These dynamics are also at play in the star, another source of change.) If the planet has an atmosphere, chaotic weather patterns can cause fluctuations in temperature and precipitation, shaping the environment further.

Now we are at the present. Every timescale up to the ones familiar with us are driven by different processes, which create a multitude of environments. On Earth, the pressure range at which we find life covers about 5 orders of magnitude, from the deep sea or deep in the crust to high mountain peaks and the atmosphere. The temperature range is around 150 degrees. Life exists in different phases of matter (sometimes in multiple phases of matter), and highly varied chemical environments.

Apparently unsatisfied with the variety presented to it, life goes on to create environments for itself, with characteristic timescales from around a century to the subsecond. If we limit ourselves to biomolecular machines that is– helicases unwinding base pairs at tens up to a thousand base pairs per second.

It remains to be seen what happens to life at timescales greater than ~5 billion years. Some suggest that it moves between heavenly bodies as stars age and goldilocks zones shift. And, needless to say, we have no data about timescales greater than 13 billion years, the apparent age of the universe. It seems possible that things will become more steady and stationary, but being so close to the start of the universe we can expect change to remain the rule for as long as we exist. Our local supercluster will stay with us and continue producing stars over timescales that dwarf what we have been through. For all that time to come, flux will be the rule.

We can witness the evidence of 13 billion years of constant change around us. We have a neighborhood of trillions of stars which for trillions of years will live and die, providing a backdrop for new and different lifeforms and new and different environments for those lifeforms to explore. The galaxy where we live will continue to evolve, with stars colliding, black holes merging, and new stars forming from the remnants of their predecessors. Change is the only rule of existence.