Brian Clegg

Of course, it is genuinely true that kangaroos use more energy or appear to use more energy when they bounce along than they consume. They seem to be able to actually give out more energy in their bounces than they've consumed in their food. And the reason for that is it's a bit like the way a rubber ball works. You know, if you drop a rubber ball on the floor, it bounces.

Of course, it is genuinely true that kangaroos use more energy or appear to use more energy when they bounce along than they consume. They seem to be able to actually give out more energy in their bounces than they've consumed in their food. And the reason for that is it's a bit like the way a rubber ball works. You know, if you drop a rubber ball on the floor, it bounces.

When I was young, they had these things called super balls, super balls that bounced really high. I don't know if you ever had one of those. And kangaroos are a bit like that. So when they hit the ground, it's not a case of all the energy they're putting into their muscles is wasted.

When I was young, they had these things called super balls, super balls that bounced really high. I don't know if you ever had one of those. And kangaroos are a bit like that. So when they hit the ground, it's not a case of all the energy they're putting into their muscles is wasted.

When I was young, they had these things called super balls, super balls that bounced really high. I don't know if you ever had one of those. And kangaroos are a bit like that. So when they hit the ground, it's not a case of all the energy they're putting into their muscles is wasted.

It's actually more like storing up energy in a rubber band as they hit the ground and then it bounces off and they use up that extra energy they've stored away. So they can do what seem to be amazing things, even though in practice they're not breaking the laws of physics.

It's actually more like storing up energy in a rubber band as they hit the ground and then it bounces off and they use up that extra energy they've stored away. So they can do what seem to be amazing things, even though in practice they're not breaking the laws of physics.

It's actually more like storing up energy in a rubber band as they hit the ground and then it bounces off and they use up that extra energy they've stored away. So they can do what seem to be amazing things, even though in practice they're not breaking the laws of physics.

It's another of those little, it's a little bit more complicated. We're oversimplifying when we say the speed of light is the limit. The real thing is the speed of light in a vacuum is the limit. So the fastest anything can go is the speed that light goes through empty space. but light can also go through other stuff. It can go through water, it can go through glass.

It's another of those little, it's a little bit more complicated. We're oversimplifying when we say the speed of light is the limit. The real thing is the speed of light in a vacuum is the limit. So the fastest anything can go is the speed that light goes through empty space. but light can also go through other stuff. It can go through water, it can go through glass.

It's another of those little, it's a little bit more complicated. We're oversimplifying when we say the speed of light is the limit. The real thing is the speed of light in a vacuum is the limit. So the fastest anything can go is the speed that light goes through empty space. but light can also go through other stuff. It can go through water, it can go through glass.

And when it does, it slows down. So light goes considerably slower through water or through glass or another solid transparent substance. And when it does that, it's closed down sufficiently that physical objects can move faster than the speed the light's going. And there's something called Cherenkov radiation that happens in nuclear reactors.

And when it does, it slows down. So light goes considerably slower through water or through glass or another solid transparent substance. And when it does that, it's closed down sufficiently that physical objects can move faster than the speed the light's going. And there's something called Cherenkov radiation that happens in nuclear reactors.

And when it does, it slows down. So light goes considerably slower through water or through glass or another solid transparent substance. And when it does that, it's closed down sufficiently that physical objects can move faster than the speed the light's going. And there's something called Cherenkov radiation that happens in nuclear reactors.

Have you ever seen a video of one of the old nuclear reactors that had water surrounding the nuclear pile? it glows blue. And the reason it's glowing blue is that little particles that are coming off out of the nuclear reactor are actually going faster through the water than the speed of light through the water.

Have you ever seen a video of one of the old nuclear reactors that had water surrounding the nuclear pile? it glows blue. And the reason it's glowing blue is that little particles that are coming off out of the nuclear reactor are actually going faster through the water than the speed of light through the water.

Have you ever seen a video of one of the old nuclear reactors that had water surrounding the nuclear pile? it glows blue. And the reason it's glowing blue is that little particles that are coming off out of the nuclear reactor are actually going faster through the water than the speed of light through the water.

And that produces a kind of optical equivalent of a sonic boom, which produces this blue glow. So yes, it's true. The speed of light in a vacuum is the absolute limit. But if we just say the speed of light is as fast as you can go, it's not true if you're not in a vacuum.

And that produces a kind of optical equivalent of a sonic boom, which produces this blue glow. So yes, it's true. The speed of light in a vacuum is the absolute limit. But if we just say the speed of light is as fast as you can go, it's not true if you're not in a vacuum.

And that produces a kind of optical equivalent of a sonic boom, which produces this blue glow. So yes, it's true. The speed of light in a vacuum is the absolute limit. But if we just say the speed of light is as fast as you can go, it's not true if you're not in a vacuum.