Is The Universe Mostly Empty Space?

The universe is mostly empty space.

Is the Universe Mostly Empty Space? Do Perfect Vacuums Exist?

The universe and everything in it, including humans, is mostly “empty space.” However, space is not actually “empty,” it’s filled with quantum fields and dark energy.[1]

In other words, even though the universe and everything in it is mostly empty (to the extent that the human race could fit in a very heavy sugar cube with the space removed), true empty space (a perfect stable vacuum) can’t actually exist in nature.

Phenomena like quark and gluon field fluctuations, and other types of cosmic radiation, permeate what we consider empty space. Even if all matter and energy could be removed from a section of space to create a perfect vacuum, the space could not remain “empty” due to vacuum fluctuations, transiting gamma rays, cosmic rays, neutrinos, and other phenomena in quantum physics.[1][6]

For an analogy we can think of the way an atom has most of its mass in its nucleus and protons, but has what we can think of as a electromagnetic field surrounding it (i.e. it’s mostly “empty,” aside from the fields created by electrons bouncing around the atom in “quantum superposition” as both a particle and a wave; see electron orbitals). So an atom is a bit like the universe, oddly empty despite having small condensed points of mass and lots of energy.

A video talking about “empty space”.

TIP: This is obvious when you think about it, but the air we breath is a gas mixture made of molecules. Thus the air is filled with molecules, which are mostly empty space, which isn’t actually empty on a quantum level due to quantum fields fluctuations. Not even the most remote part of intergalactic deep space is empty.

FACT: Aristotle said “nature abhors a vacuum” (Horror vacui), Pascal and others would later show that non-perfect vacuums exist, still later it was shown that while vacuums are useful to think about (when we are say trying to find a constant speed of light) nature really does “abhor a true vacuum” in practice. The universe, despite its sparse nature, if filled with “somethings” and we are hard pressed to find literal “nothings”.

TIP: Modern physics says the “Higgs Field,” and fields of all the other particles in the universe, permeate what we think of as empty space. This has been true since the big bang started the expansion of the universe.

Why Is the Universe Mostly “Empty Space”?

Let’s back away from the vast emptiness (or non-emptiness) of space for a moment and look at the atom. Atoms are mostly “empty space” and atoms (and their elementary particle building blocks) essentially make up ALL matter in the universe.

Atoms contain almost all of their mass in a tiny nucleus at the center of the atom (like a marble in a soccer stadium). Surrounding that nucleus are the electrons and protons (which have comparably little mass and take up next to no space). That means atoms are almost entirely made of “empty space”.

Energy Doesn’t Touch, it Attracts, Repels, and Bonds

When we touch something we don’t touch atoms (that would cause a small nuclear reaction), instead what we feel is friction from the electromagnetic force of our electrons pushing against the electrons in the matter we are touching (electron repulsion). Atoms bond together by sharing electrons and the force of combined atoms is what we think of as matter.

Now that we know atoms create all matter, and all matter is “empty space”, it’s easy to understand that, in turn, most of the universe is “empty space”.

Are There Exceptions?

Super dense things like black holes contain so much matter (particles with mass-energy) that they theoretically break the rule. We can think of them as being dense and filling space, but since all the mass-energy in the universe has always been and always will be we know that the amount of “empty space” in the universe is constant.

However, there is one other really important exception that we need to remind ourselves when speaking of this concept; “empty space” isn’t “truly empty”.

Why is “Empty Space” Not Actually Empty?

To expand on the above points, empty space isn’t actually empty, empty space looks empty because electrons and photons (light particles) don’t interact with the even smaller elementary particles and fields that are there.

Atoms Are Made of Quantum Particles

To understand this we need to understand that the nucleus, electrons, and protons of an atom are actually composite particles made up of quantum particles, and all those particles have fields. All forms of energy have fields – from quarks, to electrons, to photons, and beyond. Energy fields are actually the main thing happening in our universe (and this helps explain why we see particles like photons as both waves and particles). In fact all quantum particles have wave-particle duality and all can be understood as vibrations in their respective quantum fields. Something like the nucleus, which has a lot of mass, is really just a composite particle made of interacting quarks and gluons.

An image representing quark and gluon field fluctuations.

An image representing quark and gluon field fluctuations.

Quark and Gluon Fields

As noted above, what we think of as empty space is actually full of activity from quantum particles, specifically quark and gluon field fluctuations. The quantized movements of quarks, and the fields they create, and how those fields interact, are all happening in space we might otherwise consider empty.

However, the above quantum particles and fields aren’t evenly distributed throughout the universe (meaning some space is “more empty”) and some of the “Empty space” in the universe is also filled with things we call “dark matter” and “dark energy” and their related fields.

Dark Matter and Dark Energy

According to NASA roughly 68% of the Universe is dark energy. Dark matter makes up about 27%. The rest – everything on Earth, everything ever observed with all of our instruments, all normal matter – adds up to less than 5% of the Universe. Discovered only in 1998, this invisible stuff fills all of space and it has repulsive gravity.

We don’t really know what dark matter and dark energy are; they could be an unknown quantum field or a byproduct of the vacuum fluctuations of the known fields. Don’t feel bad. NASA doesn’t know yet and so you shouldn’t be expected to either.

Can Empty Space Exist?

Empty space can exist, in a manner of speaking. One can pull a lot of energy and clear quantum particles out of “empty space” and create a nearly empty vacuum (like the one we would measure the speed of light in). However, there are two issues.

  1. Even in an almost empty vacuum isn’t empty. Fields have their lowest energy (vacuum) state: sometimes this lowest energy state is called “vacuum fluctuations” because the fields are never exactly zero.
  2. That nearly empty vacuum is unstable, and will quickly fall back into “empty space” full of quantum particle and force interactions.

So while empty space in a vacuum can be shown with mathematics, it doesn’t actually exist in the physical universe. A true “perfect” vacuum is unstable and would collapse into quantum particles. Thus, in the lab they use “partial” vacuums to get close to empty space (ground state = lowest energy state, a non-excited state).

The result is that while we can find mostly empty space everywhere and create false vacuums, there is no naturally occurring true empty space or stable “perfect vacuums” in nature or in the lab (learn more about vacuums and empty space).


Fun Factoids About Empty Space

Keeping in mind that space isn’t technically empty, here are some fun factoids about empty space, the universe, and you:

  • If you took the empty space out of a human they would be about the size of a grain of salt.
  • You could fit the entire human race in the volume of a sugar cube.
  • Only about 5% of everything in the universe is visible.
  • If your body with it’s arms outstretched was an atom, a nucleus would be about the size of a strand of human hair.


The universe appears to be empty, but on quantum level the empty space is actually filled with things like quark and gluon field fluctuations, dark matter, and dark energy.


  1. Top 4 Bonkers things about the universe“. Retrieved Nov 6, 2015.
  2. Dark Energy, Dark Matter“. Retrieved Nov 6, 2015.
  3. Dark matter, Mach’s ether and the QCD vacuum“. Retrieved Nov 6, 2015.
  4. It’s confirmed: Matter is merely vacuum fluctuations“. Retrieved Nov 6, 2015.
  5. Gluons and dark energy [closed]“. Retrieved Nov 6, 2015.
  6. Vacuum“. Retrieved Feb 13, 2016.


  1. Outer space

"The Universe is Mostly Empty Space" is tagged with: Energy, NASA, Quantum Mechanics, Space, The Universe, Theoretical Physics

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Marc Sainte-Marie on

Nice after mocking Aether now its more Scientific DARK Forces of matter, holes, energy, and more to come, like long lost Gravitions. I’m a first hand guy, could be water for all I KNOW. It looks like the vacuum if freezing cold!

Thomas DeMichele on

Honestly, Aether was a pretty good theory for its time.

If spacetime has properties so to speak, and there is always some sort of energy fluctuation in “empty space, estimating that as Aether isn’t really too far-off of a theory.

It is probably not water though, water is a compound made of other quanta, and things don’t exist in pretty stable geometric composite particles in empty space.

Dr. Arnold J. Wolf on

What exactly do quark and gluon field fluctuations, and other types of cosmic radiation permeations consist? If matter is (mostly space) and in reality do not exist, how can the above properties also exist?

Therefore, the entire universe and all it contains does not really exist with the exception of consciousness which also does not consist of matter, particles or cosmic radiation permeations, gluons or field fluctuations.

All you speak of is a paradigm and the basic truth is that “there are no absolute truths.” For whatever the perseveres of all are not known. For all life forms have finite wisdom and without infinite wisdom cannot begin to comprehend.

Thomas DeMichele on

Quantum field fluctuations are, in overly simple terms, charged parts of space. So if you think of an uncharged field laying over literally all of space, then any vibration in that field is an electromagnetic charge (or gluon fluctuations, etc), then field fluctuations are any vibration in that field either because a quantum particle is passing through or because information is being exchanged or because a little blip is popping in and out of existence. Those little blips are literally everywhere all the time, always.

So like electrons orbit the nucleus in a cloud so fast they nearly fill up otherwise empty space over time, the universe is a bit like that.

Now to your question “is that real, or is it something else?” Good metaphysical questions! Could be a simulation, could be consciousness creating it. Could be that everything is electromagnetic energy and photons can record information and it’s a mix of all the above. Fun ideas to muse on, but we don’t know for sure!

Raghavendra on

what hapens if we delete earth and all galaxies and even empty it would be? & what it would be?

Thomas DeMichele on

From what I understand, if you delete everything then you still have quantum particles popping in and out of existence. This is why a perfect vacuum is impossible. That said, it could be that that which does exist is the cause of those “quantum field fluctuations” (sort of like static on an old tv is the result of quantum particles passing by. So, I don’t know, but since a perfect vacuum is impossible I assume that even with everything removed you would still get a bit of “static”.

As far as asking “what properties does true empty space have?” Great question, I assume nothingness has no inherent property, and that if it does… then it is not nothing and empty space is itself nothing… but I am notably now speaking of cosmology and metaphysics (in other words “could be, who knows”).

It is the sort of thing that one would want to explore and research more, if someone has a more learned answer… if is not me. If I can figure out a better theory I’ll happy post it though!

Raghavendra on

Thanks for your valuable information

rodrigo on

LMFAO, ur full of shhh, of course “PERFECT VACCUMM” exist, it is what objects are around, empty space does not in any way or form exist as a “thing”, it is empty by itself. so whatever u seel in front of u is empty, not objects tho.

Thomas DeMichele on

Hmmm, well the argument that empty space theoretically exists but not in any observable or measurable way for us is a valid concept. The space around us is, at all times, full of “things” (vibrations in quantum fields essentially)… but what is that quanta vibrating in? If you want to call that empty space that makes sense. In other words, the space around us is not empty, but “does true empty space exist?” Essentially that is a question of metaphysics.

rodrigo on

this is fucking idiotic. you’re describing matter/quantum which is not empty. not the space between me and you, which is empty.

Supports this as a Fact.


Thomas DeMichele on

It is for sure best explained as force fields (loosely speaking) in my opinion.