Since the duplicate thread was shut down, I’ll just copy my response here:
Evolution doesn’t even need to involve life forms.
Why does Earth exist? Well, because it didn’t get absorbed into the Sun or blown into pieces by a striking asteroid. It happened to exist in a spot where it was able to achieve a long-lasting, relatively static existence. Most other material of the solar system ended up quite different.
But one thing to note is that there is no “meaning” to the circularness and complexity of the Earth. We think of it as a home, as an entity, as something meaningful. But it’s not. There was material floating about in a vacuum and the physical laws of the universe acted upon it. Some material ended up becoming planets, some moons, some asteroid belts, some gas clouds, etc. The fact that some material is finely spread out in a vast mist between solar systems doesn’t mean that, that material is less “organized” or less a thing than our planet, it just ended up that way.
Evolution is basically just the observation that things which last, are the things which last. Something which can be destroyed more easily, will be destroyed more easily. Suns have a longer lifespan than planets because planets are easier to destroy. A marble stone will last longer than a limestone, because it is harder to destroy.
Now if you have a cauldron of atoms, swirling about, those atoms will either react to form molecules, or react with molecules to break them back down into atoms. Molecules which, due to the particular mixture of atoms and the laws of physics, are more difficult to break down, will continue to exist within the cauldron, instead of being broken down.
And that gives us a cauldron of molecules, swirling about. These molecules will either react to form larger, more complex molecules, or break each other down into more simple forms. Molecules which, due to the particular mix of chemicals and the rules of chemical bonds, are more difficult to break down, will continue to exist within the cauldron, instead of being broken down.
One particular instance of a chemical continuing to exist is if it is able to “eat”. I.e., it is able to take in most of the molecules that exist in the cauldron and use them to patch in gaps. That is to say, as it is broken down, it is able to build itself back up to match.
If you then extend that so that the parts which are sloughed off are able to eat and grow themselves, then you’ve really got something that can keep going.
This might sound like a rather difficult thing for a chemical to do, but fire is able to do it, for example. Propagating chemical reactions aren’t necessarily common, but they’re not unknown either.
But given billions of years and a sufficiently diverse set of cauldrons, and you might find a reaction occurring which is cyclical. For example, it might produce some waste, which another reaction turns back into food for the original reaction.
There’s no wisdom behind this. It’s just the result of the wide variety of things that exist, the long timespan, and the diverse set of results that physical laws allow for, depending on what two things you put together, at whatever particular energy level.
Large molecules can form naturally from the result of a large body of chemical reactions, over a long period of time. As a molecule becomes larger, it will usually become more ungainly and easy to break down. But, by random chance, some will be shaped in some way that makes them, instead, more difficult to break down or more capable of continuing to propagate, via a chain reaction.
And that is evolution.
The things which would not be able to persist in a larger form, have been broken down into simpler forms. The remainder will generally be in a larger, more complex form, since that particular form happens to be resistant to being broken down. Add billions of years and undersea volcanic vents, and you’ll have a pretty diverse set of complex molecules, eating one another, growing, and becoming more complex (or being broken down). Eventually, they turn into viruses and other such quasi-life-forms.