Guest:

• Lewis Dartnell, scientist and author of "The Knowledge: How to Rebuild Our World from Scratch"

What if a catastrophe occurred - a huge pandemic or a nuclear attack? Something that took us all off the grid for months or even years?

How would you manage on your own? Would you be able to keep yourself warm and find food?

Scientist Lewis Dartnell, whose research generally focuses on space, has been thinking a lot about the technology that powers our world - and how little most of us appreciate it. Even the simplest tool, like a pencil or a knife, requires a complex combination of materials and craftsmanship.

Dartnell is the author of The Knowledge: How to Rebuild Our World from Scratch, a book that examines what we'd need to know in order to survive after a catastrophic event.

So, what would be our biggest challenge?

“Human knowledge is dispersed amongst the entire network of people alive today,” Darnell says, meaning that “if civilization were to be destroyed, and 99.99% of humanity were to die off, the people left behind would find it very hard to start rebuilding from scratch.”

At first, this seems like a bold statement. Many of us know how to cook and grow veggies. Even baking bread is relatively simple: flour and water. But where do you get the flour? How close do you live to a wheat field? What about a fresh water source?

And if you’re lucky enough to be part of a very small segment of the population that lives near a wheat field, do you know when it’s ripe? How about grinding it to actually make the flour you need for your bread?

“Even something as simple as growing food for yourself, when you step back and look at the grand scheme of things, there’s technology even in there, in terms of how you turn something that happens natural and make it as efficient as you can to support cities and support civilization.”

But don’t despair.

Dartnell says we have a deeper understanding of the world than people did even a hundred years ago.  For example, we know that germs – as opposed to a vengeful deity or mysterious vapor – cause disease. You can even create a simple microscope to see germs, “and just by preserving that knowledge, you can leapfrog over thousands of years of our own history and keep yourself in a healthy state.”

Want to know more? Listen to our full interview with Lewis Dartnell, above.