We’re surrounded by the big bang.

If we spend time thinking about such things, most of us, most of the time, think of the big bang as a colossal explosion that flung energy and matter into the universe.

But that isn’t it at all. If it was, the big bang wouldn’t surround us. We’d see a source.

No, the big bang was space itself getting bigger — from a dimensionless singularity to the universe’s observable edge being 46 billion light years away from us. The universe’s edge is also 46 billion light years away from any other location in it, including locations 46 billion light years away from us. That’s hard to envision even for astrophysicists who can handle the math.

Our observable universe is 7,697,739,257,437,640,000,000,000,000 bigger than the earth by volume, more or less.

For that matter, the universe is approximately 558,658,277,253,032,000,000,000,000,000,000,000,000,000,000,000,000 times bigger than the human brain (assuming I’ve done my sums right). Steve Jobs once famously said we’re here to make a dent in it. Given the size differential that doesn’t seem likely. In fact, it’s quite remarkable we even understand as much about the universe as we do, even though only a few of us understand even a tiny fraction of what we collectively understand.

This collective we numbers 7.7 billion human beings living on this earth. Even allowing for overlapping expertise, it’s unlikely you or I understand even a thousandth of what we know, assuming, that is, we could figure out a way to assemble it all in one cognitive place.

The numbers are humbling. We’re told there are no irreplaceable people. Given how many potential replacements are available should you or I step aside, the math would seem to support this proposition.

And yet …

In round numbers, with the exception of identical twins each of us is genetically unique, and including identical twins each human being on earth has lived through a unique combination of experiences.

We are, each and every one of us, different from each and every other one of us.

We’re told nobody is irreplaceable. This is wrong, even if we look through the narrowest possible lens — departing employees whose work still needs to get done.

I’ve spoken with executives and managers who are losing experienced employees to retirement. They can, they tell me, hire replacements. The departing employees help the new ones acquire the skills necessary to perform the tasks they’re responsible for, to the extent the new employees’ raw skills aren’t already equal or superior. They “transfer knowledge” to provide context; and introduce the newbies to the most important people they’ll need to know.

But all the skills acquisition and knowledge transfer in the world doesn’t bring equivalent judgment to bear in difficult situations. Nor does it give the inbound employees a fine-tuned ability to apply their imaginations to create innovative solutions that will work within the specific context they understand from long experience.

The new employees will bring their own judgment, and their own imaginations. Their judgment and imaginations will operate within the context of where they came from, not from where they are now. Their knowledge and imaginations will be different, which means their results won’t be the same as those of their predecessors.

Skills are teachable. Knowledge is transferrable. Judgment and a deep understanding of context are neither.

Each human being who works with or for you is unique. Robots are not, which is what makes them desirable alternatives to human workers on assembly lines: Because they’re identical, they’re predictable.

The best leaders and managers only want robots in assembly line sorts of work. They help the men and women they work with develop their judgment and encourage them to be imaginative in addressing their daily challenges.

They figure out what each unique and irreplaceable employee does best — what unique contributions they can make with the right opportunities — and turn them loose.

None of us will ever make a dent in the universe, and very few of us will even make much of a dent on the earth. We can, however, make the tiny patch over which we have some influence better for those we share it with.

We’re each unique and irreplaceable, especially among the irreplaceable people we choose to surround ourselves with. On the other hand, with billions of fellow humans on hand the world can probably get along without each of us if it needs to.

Somehow, I find both formulations reassuring.

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Have a superior solstice, happy Chanukwansamas, peppy perihelion. Or, enjoy whichever other seasonal expression of good cheer you prefer. Just do something to make yourself smile.

I’ll be taking a couple of weeks off, but I’m confident you’ll manage to keep your own joints running just fine without me.

See you in 2019!