Should It Be “Space-Time” or “Space Time”? And Why Does It Matter?

One of the most challenging aspects of writing a book is the need for authors to seek out blurbs. These endorsements, prominently featured on book covers, can entice readers to make a purchase. Right now, I’m at this stage with The Edge of Spacetime, reaching out for letters of recommendation, asking people to read my work and share positive thoughts in return for something more than just my good intentions.

It’s a bit nerve-wracking, yet it can also be fascinating. Those whose endorsements get published were asked in a specific format—what prompted you to use “space-time” with a hyphen rather than “spacetime”?

This seems like a question of simple grammar, but there’s a deeper issue at play. When discussing space or time individually, we have an intuitive grasp of what we mean. The term “space-time” is somewhat newer to scientific discourse. Historically, many cultures have embraced a unified concept that doesn’t differentiate between space and time as distinct entities.

For me, as a science communicator, explaining this concept is quite challenging. Even articulating “space” is complex. I might say space is where movement occurs, but movement also happens within time. I could define space as the realm where things exist, but a similar statement can be made for time. We even pondered describing space as a geographical location, yet that sounds overly academic and abstract. Essentially, we are referring to a site of spatial dimensions.

To elucidate, there are three dimensions of space and one dimension of time, but time only flows in one direction.

However, as Albert Einstein famously asserted, these aren’t separate phenomena. Observers moving at varying speeds, especially as they approach the speed of light, may disagree on when certain events transpire. They may also hold differing views on the size of objects. To truly understand everything, we must quantify space-time rather than merely space or time. This perspective might not feel intuitive, but it is the most effective way to comprehend the mechanics of the universe.

In this regard, it’s worth considering whether space-time represents a confluence of two familiar phenomena or signifies the emergence of something entirely new. This is where the nuances of grammar reflect our scientific understanding, at least from my viewpoint.

My last name includes the very first hyphen I encountered. My parents chose to keep both surnames, so to me, Prescod Weinstein signifies both identities.

The hyphenated version of space-time can be interpreted as indicating that what we discuss encompasses both space and time. Conversely, removing the hyphen to form “spacetime” may suggest we are addressing an entirely distinct entity. It embodies attributes of both space and time while existing as a separate third entity.

Are we contemplating something that is both space and time (space-time), or are space and time merely approximations of a fundamentally different conception of space-time? I find myself somewhat ambivalent. In my earlier book, The Blurbriter, I noted this distinction without employing hyphens, thus raising the question of why I chose to make a switch this time around.

The straightforward answer is that the title of the new book appears in the introductory sections of classic cosmology texts. Large-Scale Structure of Space-Time by Stephen Hawking and Father George Ellis states in the very first chapter that solving the equations that describe the universe “in a sense, involves contemplating the edges of space-time.” Just two pages later, they posit that locations where equations deconstruct (like at the heart of a black hole) can be viewed as “representing part of the edge of space-time.”

My book includes chapters that elucidate the types of equations they reference and the role of boundaries and edges in physics. Since I was about to borrow this phrase for my book’s title, I felt compelled to adhere to their terminology.

This is a surface-level explanation. However, at a deeper level, I am unsure where I stand. Like my request for endorsements, I feel inclined to prefer “spacetime” without a hyphen. Yet, I’m also aware of how habitual language can be, given my repeated use of hyphens in the subtitles of my previous work. Scientifically, I lean toward the notion that “space-time” encompasses both space and time, asserting that it is an entirely different fourth dimension: space-time. This may seem like a complex perspective, but I desire to embrace both aspects simultaneously!

Chanda’s Week

What I’m reading

I’m quite excited about the new Charlie Jane Anders novel Lessons from Magic and Disaster.

What I’m seeing

I’ve just caught up with the sci-fi series Invasion, and it’s truly captivating.

What I’m working on

I have a new postdoctoral researcher joining my group.

Chanda Prescod-Weinstein is an associate professor of physics and astronomy at the University of New Hampshire. She is the author of Cosmos with Disabilities and her forthcoming book, Edges of Space-Time: Particles, Poetry, and the Dreams of the Universe.