My son is a big hiker. Last fall he trekked down the coast of Portugal, averaging thirty or so miles a day. Long, silent hours spent all alone on a windy expanse of rocky coastline.

I asked him what he thought about during all of the silence – how did he fill it? Did he contemplate any deep issues?  No, not really, he said – after a while his thoughts dispersed and his mind was washed clear and empty.

I think that image is so beautiful: a busy, creative mind at peace, with only salt air blowing through it.

There is a fullness to emptiness. And we run and walk and write to try to find our way towards that place.

Over a year ago, I started writing to try to understand my pain in the grief of my mother’s death. But I think now that it’s been less about the pain as it is about coming to terms with the phantom emptiness.

Last month, in New Hampshire, when I said goodbye to my father, I looked back in the rearview mirror and saw him standing alone, apart from the others. It looked like he was still making room for Mom next to him, in the space just under his shoulder.

I’ve been learning to live with that empty space in my life, but I’m beginning to find my way towards something solid.

All through our lives we are led to believe that the glass is either half full or half empty. But now I see that it is both. And the empty part is just as important as the full – both halves of the same container.

In the movie The Theory of Everything, the character of noted physicist Stephen Hawking is shown as a man who accepts the parts of his body that have failed him – the voluntary muscles that control all of his movement. Where many might see him as half a man, he sees only a challenge.

And his deteriorating exterior is a container simply brimming over with curiosity and intellect.

He refuses to let people see him as a glass half full.

Aptly, he also seems to be a man obsessed with black holes. Where others see darkness, he imagines infinity.

And the woman he loves, after learning about his illness, responds in a way so touching, with utter acceptance. What we expect is her grief, her anger, but, in the film, her immediate response is love.

She recognizes, and yet looks beyond, the glaring disabilities – the broken, incapable pieces. Romantic maybe, but inspiring as well.

Hawking once said that we are just an advanced breed of primates on a minor planet orbiting around a very average star, in the outer suburb of one among a hundred billion galaxies.

But he believes we crave an understanding of the underlying order of the world. And that there must be something special about any so-called “boundary theory of our universe.” And, he said, what can be more special than the theory that there is no boundary?

One day when I was in pre-school, I remember my mother picking me up at lunchtime. She had a surprise: she had been to the bank downtown and they had given her a cardboard-covered can, shaped like a tube, with the bank’s logo on it.

It was for my savings. And she had already put a quarter in it for me. I shook it – how exciting, I was rich! But she told me the only way to get the quarter out was to turn it over and cut it open.

I thought about that. It was agonizing. I wanted that quarter. I didn’t make sense to me which was the gift – the can or the quarter?

Of course I was just too greedy for what was inside and I begged her to open it. She tried to explain that the bank would be useless if she did. But she finally pried it open and, naturally, I burst into tears.

Because now my cheap bank was ruined. But I had my quarter!

But an almost philosophical question ate at me: where did the bank go? Had it ever existed? Or did it only exist when it had a coin in it? But what was the coin without the cardboard around it? The cardboard was now trash, but the coin remained.

Silly, yes, but it seems like a version of the empty/full glass problem.

In a way, Stephen Hawking’s theorems relate to my own meager theory: we will always find the holes in our lives – what we have loved and lost – but what if that emptiness isn’t a space, but a solid entity.

Okay, I’m not very good at this, I read that last sentence and was confused too. I don’t even know what physics is.

But when I think of loss, and death, I imagine myself like a goldfish, with bulgy eyes staring, unseeing, out into the vast unknown.

And maybe there isn’t a glass boundary after all.

Poets and physicists are more alike than different: they both describe and attempt to explain a universe no one else can actually see. Their ideas require a faith in an overarching theory: that a larger reality exists.

Think about this when you are alone, or taking a walk, or when you are staying busy, trying to avoid feeling empty. Try to see it as an opportunity to let the other dimension in – the emptiness, the other half.

Maybe you’ll actually find the piece you thought was missing –  acceptance from a parent, the peace made with an ex-husband. A difficult aspect of yourself – your anger, your depression, a hurt you’ve been nursing, a personal disappointment.

And maybe you’ll discover that nothing was really missing after all – it was there all along, another piece to the whole – another dimension to touch, embrace.

For me, I’m recognizing that this is new territory with my father –  the family get-togethers, the celebrations. Dancing around an empty pit. But the pit isn’t vacant at all – it’s full of Mom and all of the love she embodied – the bread and butter of my memories.

It’s the coin and the cardboard that I have to put back together.

I’m reclassifying the empty/full objects on this fractured, faltering planet. Less black and white and divided – more rounded and colored in. People with disabilities, mental illness, strangers, people I disagree with – why see only the broken fragments?

Because maybe there’s no no boundary after all, just our own little brains worrying and fretting.

And just for today, I want to envision my mind as a beautiful, limitless vessel of imagination. Not like a full glass, more like a Tibetan singing bowl.

A vibrating basin of pure, clean melody that sounds as if it is touched by ancient tears.  With peals that seem to go on forever, across the expanse of ocean and sand, into infinity.

Empty and full, echoing in our tiny, empty ears, and changing frequency as the tones expand out over the salty air.

Romantic, yes.

But if I can imagine it, isn’t it possible?