Hannah starts her journey by asking whether everything could be bigger, finding out what life would be like on a bigger planet. As the Earth grows to outlandish proportions, gravity is the biggest challenge, and lying down becomes the new standing up. Flying in a Typhoon fighter jet with RAF flight lieutenant Mark Long, the programme discovers how higher G-force affects the human body, and how people could adapt to a high G-force world. But by the time Earth gets to the size of Jupiter, it's all over, as the moon would impact the planet and end life as we know it. Next, Hannah tries to make living things bigger. The programme examines the gigantopithecus, the biggest ape to ever exist, creates a dog the size of a dinosaur and meets Sultan Kosen, the world's tallest man. Humans are then super-sized with the help of Professor Dean Falk to see what a human body would look like if we were 15m tall. The sun gets expanded, and Professor Volker Bromm looks back in time to find the largest stars that ever existed, before the sun explodes in perhaps the biggest explosion since the big bang.
Having discovered in the first episode that making things bigger ends in disaster, in episode two, Hannah is going the other way by asking whether everything could, in fact, be smaller. But going smaller turns out not to be much safer...
