Everyone knows outer space is big and empty but what about inner space?  What about the space inside solid stuff like tables, chairs and the goo of our bodies? One of the strangest and least appreciated discoveries of modern physics is that solid matter is – to put it bluntly – a big fat lie. 

Consider, for a moment, the chair your butt is resting on right now (or the floor if you’re standing).  It’s made of a squillion atoms, right?  And since it's a solid, all those chair atoms are packed tightly together like a vast collection of marbles in a box, right?  And it’s all those tightly packed atoms/marbles that are holding your butt in the chair against the force of gravity, right?

Nope. That whole “atoms-as-marbles” picture is entirely wrong. 

Every atom is has two components. There’s the nucleus at the center (made of protons and neutrons) and then there’s a bunch of electrons wizzing around the nucleus.  But it’s not like those images we got in high school with electrons circling just outside the nucleus. In reality the electrons are a hundred thousand times farther from the nucleus than the nucleus’s own width.  If the nucleus were a beach ball in Midtown Manhattan, then the electrons would mustard seeds living in an apartment in Philly. 

And what does that mean?  The atoms making up your chair –the ones supporting your booty right now – they are pretty much all empty space. Each one is a vast stretch of nothing lightly salted with an occasional fleck of stuff wandering in an endless void.  And as atoms go, so goes your chair – its just empty space too.  That image you had of solid matter as tightly packed marbles?  Nope. Not even close.

But now comes the $64,000 question - if atoms are nothing but deserts of empty space, how does your butt even know the chair is there?  Why don’t the flecks of butt-matter in the endless void just pass right through the flecks of chair-matter in their endless void?

The answer is as simple as it is weird.  It’s all just forces.

Cracking like lightening through the void, all the specks of electrons and the specks of nuclei are constantly interacting through a force called of electromagnetism.  Each interaction is carried out through the jolting exchange of a particle of pure energy called a photon (which is really just a nubbins of light). Each photon swapped gives a little push or a pull – a force - exerted across the emptiness.  That’s really what’s keeping the stuff we call your butt from drifting through the stuff we call your chair.

So the truth of the matter is there is no “solid” matter.  Everything you think as solid – tables, chairs, a 69 Cherry Red Ford Mustang – none of it is really solid. Instead there are only rapid-fire bursts of pure energy carrying forces between impossibly small flecks of somethingness. And all of it lost in an atomic void as empty as intergalactic space.

Think about that the next time you plop your butt down in a chair.

PS. What does this all empty space mean?  Leave a comment on the website version of the post or email me at [email protected] 

— Adam Frank 🚀