Sixty thousand years ago our ancestors lived as hunter-gatherers, steadily recolonising the world after the Toba supervolcano in Indonesia almost wiped them out, reducing the entire species to a single enclave in the land their descendants would one day call Africa.

Their world was ranged across a few hundred square kilometres at most. They had not yet learned to follow the migrating herds of the plains, or begun our race’s long partnership with those other predators, wolves.

Today the edge of our world is the limit of the visible universe, lying in all directions in space, 13.75 billion light years away.

The only difference between our paleolithic ancestors and ourselves is our access to finer tools, themselves the products of millennia of invention.

Yet the greatest inventions now at our command aren’t tangible things at all. They’re science and mathematics, which give us the power to put into words and symbols ideas which we could otherwise never grasp.

To be clear about it: science is not about proving anything, showing how something works, or what it even is. It evolved from a growing understanding of the very limitations of knowledge, a debate played out in the eighteenth century.

Science represents a new, different kind of knowledge than had existed before.

And a disturbing one.

Go on the internet and look up the topic of evolution, or how the universe began, or any of a dozen other topics on which science has cast its light recently, and you will get nearly as many hits from religious organisations as scientific ones.

These essays, books, talks and commentaries have a common factor: their combative defensiveness. Even now science threatens the basic beliefs of many people, though we all live in a world shaped by it. There is a deep psychology of fear inside us at the thought of it.

We all love our own ideas, but most of all, we love them when they are safe ones, when no-one is going to come along and tell us we’re wrong.

The backlash against science is nothing new. In Dickensian England thousands died for the greed of the few who built what became known as “dark satanic mills”, or owned the mines which fed them.

All knowledge can be used for good or ill, and there’s no doubt that we’d be better off if some things had never been invented. The trouble is, unfortunately, it only takes one side to start a fight, and people are really good at dehumanising, and closing their eyes to the suffering, of
others.

Science proposes models, or possible ways that things might work - for instance Newton’s law of gravitation, which says that the force of gravity drops off with the square of the distance between two objects. In other words, if something weighs four kilos on the surface of the Earth (ie about 7000 km from its centre of mass), if you move it out to 14,000 km from the centre of mass, it will weigh only one kilo.

This theory is precise, mathematical, and able to be tested. A century ago it worked perfectly, until our ability to test it became so accurate that we found it didn’t work exactly as it was written.

So we had to come up with a new idea - in fact, a new kind of idea.

Einstein wondered what would happen if we didn’t think of gravity as a force reaching out between objects, but instead as a property of space itself.

And it worked. It fitted the observations better.

Now we think in Einsteinian terms, not only of gravity, but of space itself. The fabric of the world has itself become an active participant in the universe as we think of it, instead of just a passive background or stage on which things happen.

Of course, that doesn’t make either idea right. Scientific theories doesn’t tell us anything about reality. It's not their job. They don't even need to try.

Science can’t prove that the Earth wasn’t created in one day in 4004 BC, or that the dinosaur fossils we keep finding weren’t deliberately buried there between those layers of rock for the sole purpose of confusing paleontologists.

Science is like any other invention. How we use it - whether to destroy ourselves or to colonise the stars - is up to us. But whichever we choose, the result will not be the fault of science or any external fate or destiny. It will be because we choose it - a measure and judgement entirely of our own courage, or cowardice.

With the unprecedented things happening today - our immense power and physical control over the world, our catastrophically spiralling population - we have a choice. Do we understand what we could be, if we wanted it enough?

Or do we fade away in a false Indian summer, watching TV or playing computer games while it all collapses around our ears, waiting for someone else to do what we know needs to be done, yet unwilling to do it for ourselves?