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Series 2: 15. You Shrunk the Earth
We find out what would happen if you shrank the earth. You could jump higher and move faster, but you would end up with altitude sickness even at sea level.
Source: CBBC
Most recent episodes of Hey You What If?
Hey You What If?
Series 1: 6. You Could Levitate?
Good news - it’s possible to levitate! Bad news – there are some serious side effects.
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Series 1: 5. You Could Go On Holiday To Mars?
Experience the ultimate in long-distance travel - a holiday on Mars!
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Series 1: 4. You Could Turn Into A Giant?
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Series 1: 2. You Could Dig Through The Earth?
The deepest hole humankind ever dug only got one thousandth of the way through the earth. But what would happen if you kept digging?
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Series 1: 1. You Fell Into A Black Hole?
Experience the most extraordinary ride in the universe – falling into a black hole.
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Series 2: 26. You Could Walk Up Walls
We take inspiration from the natural world as we imagine a new kind of superhero that can walk up walls.
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Hey You What If?
Series 2: 25. Earth Ran Out Of Energy
We try out a crazy idea from science fiction to build a giant sphere around the sun and give us more energy than we'll ever need.
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Hey You What If?
Series 2: 24. You Surfed Without Water
If the beach is too far to go but you still want to spend some time surfing waves, then why not surf on land instead? Well, there are some very good reasons people don’t s ...
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CBBC
Hey You What If?
Series 2: 23. You Were Indestructible
On the face of it, humans are a bit breakable. We have these hard skeletons that can crack if you have a tumble. But if we were indestructible, like a superhero, then we&rsquo ...
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Most popular episodes of Hey You What If?
Hey You What If?
Series 1: 4. You Could Turn Into A Giant?
Find out why turning into a huge giant would be no fairy tale.
13-05-2026
CBBC
Hey You What If?
Series 1: 5. You Could Go On Holiday To Mars?
Experience the ultimate in long-distance travel - a holiday on Mars!
14-05-2026
CBBC
Hey You What If?
Series 1: 6. You Could Levitate?
Good news - it’s possible to levitate! Bad news – there are some serious side effects.
15-05-2026
CBBC
Hey You What If?
Series 1: 3. You Could Take A Lift To Space?
What would happen if there really was a lift that took you all the way up to space?
12-05-2026
CBBC
Hey You What If?
Series 2: 4. You Needed Two Of You
From cloning to 3D printing, what if we could actually make copies of ourselves?
13-03-2026
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Hey You What If?
Series 1: 26. You Could Fly Like A Bird?
Anyone can fly like a bird – you just have to travel across the solar system to do it!
09-03-2026
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Hey You What If?
Series 1: 2. You Could Dig Through The Earth?
The deepest hole humankind ever dug only got one thousandth of the way through the earth. But what would happen if you kept digging?
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Hey You What If?
Series 1: 14. You Could Live On The Moon?
Some day people will live on the moon – find out just what they are in for.
12-02-2026
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Hey You What If?
Series 2: 5. You Could Stop Global Warming
Imagine if we had a thermostat that could turn the world temperature down - could we fix global warming? But be careful, a few degrees too far could cause an ice age.
16-03-2026
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Hey You What If?
Series 2: 1. You Built A Mega Slide
Could you build a slide to the other side of the world? You would need to start in space, use the slippiest slide ever and make sure you have enough supplies before you go down it!
10-03-2026
CBBC