Curious Kids

What is space made of – what does gravity actually bend? – Phil, age 12, Birmingham

The word spacious does not necessarily mean empty. It simply indicates that there is enough room to move around the objects inside it. Similarly, outer space is not completely empty. It is vast and forever expanding, but there’s a lot of stuff in it.

Dark matter and dark energy

Scientists predict that an as-yet unseen form of matter that does not emit light or energy, called dark matter, makes up a significant portion of the universe’s mass. Researchers guess that it exists because they can see its gravitational pull on other visible matter.

Similarly, scientists predict a mysterious form of energy called dark energy is driving the accelerated expansion of the universe. Unlike dark matter, dark energy is not related to matter or gravitational forces, but it’s a property of space itself.

Imagine the universe as a balloon. Dark matter is like the balloon’s material, affecting its shape, while dark energy is like the air being pumped into it. It doesn’t change the balloon’s material, but it influences how quickly the balloon expands.