Why don't tropical beaches melt? It's a fair enough question. Think about it: all that sizzling sun pounding down day after day, week after week, year after year, turning the sand into one big, shifting, foot-scorching hotplate. What happens to the heat?
Enter Professor Brian Cox, in his wonderful new series Wonders of Life, to explain it all.
When the sun goes down, the cooling sand releases all the energy it's taken in during the daylight hours.
But since energy is eternal and can neither be created nor destroyed, and since the amount of energy circulating in the universe is fixed, the energy the sand absorbs from the sun is recycled in a different form.
Simple, eh? Well, maybe to you, but I'm a dolt who was despairingly clueless at Leaving Cert science. Cox's brilliance as a television presenter -- and as a scientist -- lies in his ability to take complicated ideas and communicate them in comparatively simple and compelling terms that even a dullard like me can just about grasp.
In Wonders of Life, he uses physics to unpick huge questions: "What is it that makes something alive, and how did life begin in the first place? What is the difference between the living and the dead? What is life?"
He began his journey in the Philippines on the Day of the Dead, when people honour the souls of the departed, who they believe are still all around them. "It feels right," said Cox. "It's hard to accept that when you die, you stop existing".
You don't, of course. According to the second law of thermodynamics, which underpinned everything in this episode, the energy created by every living creature -- which Cox amusingly pinpointed with the help of a thermal imaging camera and some nifty graphics -- is out there after they die, swirling around in some form or other. The great paradox is that while the universe is decaying and heading for disorder, life goes on.
"The story of evolution is just the story of the transformation of energy from one form to another," he said. Proton gradients, "the universal spark of life", are common to every living thing on the planet, from humans and animals to the trees and plants and single cell organisms that existed at the dawn of time. In other words, life on earth was an inevitable consequence of the laws of physics.
If this all sounds a bit dry, it wasn't -- not least when Cox took a sample of his own DNA by spitting into a test tube and mixing the saliva with washing-up liquid, salt and vodka to isolate the strands.
Marvellous stuff, but exceeded by the sight of Cox swimming in a pool teeming with tens of millions of pulsating golden jellyfish, which contain hundreds of different algae and draw their energy, their life force, from the sun.
A schoolboy could tell you it's photosynthesis . . . just not this schoolboy, back in the late 1970s.
It's hard to believe that the channel which makes Wonders of Life also makes Top Gear. "We're back with a new look," boomed Jeremy Clarkson. "We have changed EVERYthing!"
This being the smug, smirking, circular world of Top Gear, what he really meant was they've changed nothing at all.
Clarkson is looking very old for his 53 years these days. The formula looks old, too. Richard Hammond roars along in a Pagani supercar that won't leave much change from €1m. James May tests out the new Bentley while wearing a hideous rugby shirt.
Clarkson takes the wheel for the weekly stunt, an interminable item that sees him driving around in the world's smallest car, a thing called the P45 that he's supposedly built himself, and then pitching it on Dragons' Den.
Some 20 minutes of this drivel leads to a feeble punchline: "All the Dragons have given me a P45." If only BBC2 would. Wonders of Life HHHHH top gear HIIII