Why is space vacuumed?

Gravity is king

Generally, space would be quite empty, even without gravity. ” There’s not a lot of matter in there which is relative to the size of the universe,” said Cameron Hummel, a theoretical astrophysicist at The California Institute of Technology. According to NASA, the average density of the universe is 5.9 protons (subatomic particles that carry a positive charge) per cubic meter. But because gravity pulls matter together in the universe, it further amplifies the emptiness in certain areas.

Basically, any two objects with weight will be attracted to each other. This is gravity. In other words, “matter likes to be around with other matter,” Faherty says. In space, gravity pulls objects around closer to each other. Being together, their collective mass increases, and more mass means they have a stronger gravitational pull, which in turn pulls more matter closer to them. Firstly, the mass increases, then the gravitational force, then the mass. “It's a uncontrolled effect”, Hummel said.

Hummel said, as these gravitational hot spots continue to attract nearby matter, the space between them is evacuated, creating a cosmic void. But the universe was not like this at the very beginning. After the Big Bang, matter in the universe was spread out more evenly, “almost like a fog”, he said. But over billions of years, gravity pulled the matter together to form asteroids, planets, stars, solar systems and other galaxies; And left holes between the planets, the stars and the galaxies.

However, the vacuum in space is not 100 percent pure empty. Between galaxies, there is less than one atom per cubic metre of space, which means that intergalactic space is not completely empty. But it is far less than the amount of matter that exists in a vacuum that humans have simulated in a laboratory on Earth.

At the same time, “the universe keeps extending,” Faherty says, this ensures that most of the universe is empty.” It sounds utterly lonely.”