Does Gravity Exist In A Vacuum?

Gravity is one of the strangest forces out there. While scientists can prove gravity has an effect on things, there is no actual proof for what the facets that make and effect gravity are.

For similar reasons we don’t always understand the nature of gravity and where it exists. 

The question we are posing today is one of science’s annoying paradoxes. Gravity exists everywhere, we don’t really know why, but as long as mass exists so does gravity.

This means that in space and in a vacuum gravity will still exist, there are a few reasons why people think otherwise. 

 We explored these questions in the guide below, read on to learn more about gravity.

What Is A Vacuum?

To first understand the answer to this question we must understand what a vacuum, a true vacuum, actually is. 

A vacuum is a space that is completely devoid of matter. In other words, a vacuum has nothing in it. To be a true vacuum there needs to have absolutely no matter within it.

Clearly, to achieve a ‘perfect vacuum’ it is really hard and will require a lot of work and equipment that will cost a lot of money. As a result a perfect vacuum is pretty rare and some think even impossible.

For instance in a lab, you may refer to a vacuum chamber as being a ‘vacuum’. In fact, this is actually a partial vacuum, there is less matter than our normal atmosphere but there is still some matter within this space.

Importantly, space, as in what exists outside of Earth’s atmosphere, isn’t actually a perfect vacuum at all.

Outer space is potentially the closest thing we can get to a perfect vacuum, as it is extremely low density but as we mentioned a perfect vacuum that is completely free of matter is near impossible. 

More importantly, in space there are often still many hydrogen atoms per cubic meter.

The fact that outer space, even interstellar atmospheres, are not a perfect vacuum is exactly why we exist and why the Big Bang happened.

We would not exist within a perfect vacuum as there would be literally nothing by the nature of a perfect vacuum.

So, Does Gravity Exist In Space?

We have all seen footage of astronauts floating around their ship and even within outer space itself, seemingly pushing around equipment that could weigh tonnes. This must only be possible because there is no gravity, right?

This is not the case. What exists in space is known as microgravity, or popularly as ‘zero gravity’ although this isn’t used as it is misleading.

In essence, gravity does exist in space but at a very small level, which is what allows ‘zero gravity’ to be a thing.

For instance, the fact gravity does exist in space, an imperfect vacuum, is exactly why the planets orbit the sun. If there was no gravity there would be no atmosphere.

This is the issue on the moon as there is such little gravity there is not an atmosphere which we can breathe happily within.

If there was no gravity on earth then there would be no atmosphere and we would all suffocate rather than float around.

Then What Is Happening In Space?

In outer space people can float inside and outside the spacecraft and objects, as well as our bodies, seem weightless. It is important to differentiate weightlessness from no gravity.

What we call zero gravity in space is actually a different thing to if there was completely no gravity. This is to do with free fall rather than gravity, which is why you can experience ‘zero gravity’ on Earth with an airplane.

Even when you crest a hill you enter a state of free fall technically as you are moving against the natural gravitational direction gravity is pulling you.

In a rocket you are essentially moving sideways so fast that you enter a state of free fall as you are still being pulled towards the earth’s center but you don’t actually get closer to the earth’s center.

The effect of being dragged towards the earth while moving sideways simultaneously, creating free fall. 

You can achieve this level of ‘zero gravity’, or more accurately weightlessness, on Earth which proves that gravity and weightlessness can still exist in tandem.

An airplane can fly in an arc known as a parabola. As the airplane reaches the apex of the curve the plane enters a brief period of free fall that relies on similar physics to a spacecraft.

Gravity still very much exists and is required for this free fall to even exist. Similar to centrifugal force, a parabolic trajectory can lead to free fall. 

This happens all the time in daily life. If you bounce a ball it will naturally bounce upwards due to other forces and then slowly drop down because of gravity, forming its own parabola shape. 

Again at the apex of this trajectory the ball is technically in free fall and is extremely briefly free of the constraints of gravity, even though gravity is still an acting force upon the ball.

Can Gravity Exist In A Vacuum?

Yes, gravity does exist in a vacuum, as gravity exists everywhere. In essence, a good rule of thumb is that where there is mass there is gravity. Without gravity we do not have mass. In reality, without gravity we have nothing.

In other words gravity has nothing to do with atmospheric pressure, we know this because gravity exists in space, beyond our atmosphere. Gravity is related to mass. 

So, in a vacuum an object still has mass so there is still some gravitational force at play. For instance, in a vacuum if you drop two objects they will still move towards each other.

Moreover, the laws of motion basically rely on gravity so if an object moves it is likely there is gravity at play.

Final Thoughts

As you can see gravity presents some interesting issues for scientists and physicists alike. The main issue here is that we don’t know what gravity is or why it exists or what causes it to exist.

Gravity is only observable as a cause. We know motion is governed by gravity, but not why. We know mass is measured against gravity and exists because of it, but we don’t know why. 

The true nature of gravity is very hard to understand, it exists everywhere but is incredibly hard to measure accurately.

Moreover, terms such as zero gravity and pop physics have, without malice, ended up becoming misinformation. 

What happens in space is not zero gravity at all, it is mainly to do with free fall and weightlessness which in fact only exists because gravity does. 

This misconception of gravity is why people think a vacuum may affect gravity. When in fact, outer space is neither a perfect vacuum nor totally free of gravity.

A perfect vacuum means there is literally no matter present in it at all. But it is not air that affects gravity, it is mass.