I started writing about sci-fi worldbuilding back in August. Haven't posted properly in a while because it takes me time to get my thoughts in order, and I am trying to focus on revising Tiamat's Nest while also beta reading for a friend.
However, one of the comments last time gave me pause for thought. I was talking about the possible diversity of life in a universe where life has arisen independently on many worlds, and Alex pointed out that you'd need a lot of scientific knowledge to invent convincing alternatives, and the worldbuilding would be impossibly detailed.
I felt this was worth a bit of exploration.
Building alternative life forms
My last post, Diversity Rules, was meant to show where certain assumptions about the origins of life would logically lead - at one end of a very broad spectrum.
If you decide to invent a novel form of life and go deep into its biology, psychology, ecology etc. then I think Alex is right. It would be a gargantuan task.
But if you want to keep life forms and biology close enough to known forms for comfort, there are many ways to do so by choosing a different starting point or invoking suitable organizing principles.
And even if you want diversity and novelty, you don't need to go overboard on the details. For example, E.E. "Doc" Smith's Lensman universe is peopled with hugely varied species with an inventive array of body plans that are not simply derivatives of earthly forms. Sure, he makes some simplifying choices. Warm-blooded oxygen-breathing humanoids predominate, for example, but he pays suitable lip service to the common Arisian seed for life in the two galaxies and moves on. The biological details are not overly important.
In other words, you can choose to go as detailed as you want, but it really needn't be too onerous - just enough to paint the scene in terms your reader will accept. I think this last bit is vital. Do what is appropriate both for your story and your audience. Some are more demanding than others.
The importance of research
Having said that, I think you do need a certain amount of scientific literacy to write convincing science fiction. This doesn't mean you have to come from a scientific background, but you owe it to yourself to do the appropriate research.
In this, sci-fi is no different from any other writing!
If you were to set a spy thriller in London, and have your counter-espionage heroine stepping across the road from Westminster Abbey to the Tower of London, many readers who don't know London would likely not blink an eye - but many would point out the geographical absurdity. And if a character in London decides to take the tube, you'd better have at least a working knowledge of the underground network and what it's like to ride it.
That is called research. Authors do it all the time when they need to paint a convincing setting for their real-world stories.
Just because your story is set in another space and another time, don't expect a free pass. Remember, it's called science fiction for a reason.