Earth has been around for about 4.5 billion years. The universe has been around for about 13.8 billion years.
Taken by themselves, those two numbers probably feel more or less the same. They're both incomprehensibly large, so it's hard to grasp the difference in scale.
And they're both tiny next to the number of years it may be until the universe ends. According to one physics theory, the number of years until the end of the universe is a googol: 10 raised to the 100th power.
Numbers with so many digits "become meaningless, obviously," Rachel Sussman told Tech Insider. "It's like, that's a whole lot of zeros."
Sussman is an artist who likes thinking about time. It featured prominently in her first book, "The Oldest Living Things in the World," which came out two years ago. She returned to the theme for an art installation called "A Selected History of the Spacetime Continuum," part of an exhibition at the Massachusetts Museum of Contemporary Art called "Explode Every Day," focused on exploring the idea of wonder.
The new installation, which runs through April 2017, offers a visual representation of something that is nearly impossible to comprehend: the timeline of our entire universe, from birth until death.
Beyond a human lifetime
"Our brain doesn't naturally compute something like [a googol]," Sussman continued, "because why would we need to?"
But grappling with numbers that large could, Sussman hopes, make us better able to tackle the problems we face.
"How do we change up our very sort of stuck human perception of time that's very physiologically based?" Sussman asked. "I think it's really important to step outside not just the moment to moment or year to year, but to step outside the human lifespan."
It's hard to conceptualize periods of time that go so far beyond even generations of human lives. But zooming out — way out — can be valuable.
"Our world isn't in the best state these days," Sussman says. "Long-term thinking really is something that benefits us all and really is a moral question."
The timeline shows Sussman's concerns, but it also shows her joys. "I assume that the edges of the universe are sparkly," Sussman laughed.
The sparkles come at the top and bottom edge of the horizontal timeline, which wraps along the walls of a room in the museum.
The timeline is built into the existing room, adding an extra layer to the work. Two fire alarms mark the wall near the very beginning of time and the death of the Milky Way.
A doorway between the short wall that holds all of history and the vertical bar marking the very moment of the present looks into another gallery displaying another installation, a painting of cathedral-like trees peering through. Just past the death of the universe, a staircase drops into the room.
The five eras of the universe
Sussman encountered the estimate for how long the universe has left to "live" when she discovered the so-called five eras of the universe.
The theory, which outlines the life and death of the universe, was originally published in a 1997 article in Reviews in Modern Physics by the physicists Fred Adams and Gregory Laughlin, who in 1999 published a book expanding on the idea. Their paper has since been cited hundreds of times.
The five eras became the guiding principle of Sussman's timeline, which starts before the Big Bang and ends when the universe is left as "cold, dead, empty space."
That prospect doesn't get Sussman down. Not only is it an incomprehensible number of years from now, but it has a sort of poetic justice to it, she says.
"There's so much energy and expansion happening, and that's not permanent, and this idea that so much transformation will happen that will eventually end in decay — it makes sense to me, just in the same way we have our life cycles, of humans and plants and animals and things," said Sussman. "These things have booms and busts."
The boom, of course, came 13.8 billion years ago with the Big Bang, when the universe first began to expand. But Sussman's timeline starts before this, in a time when everything is a hypothesis. "It creates the sense of play because it's a little bit funny to think I'm starting before the Big Bang," said Sussman of her choice.
Throughout the timeline, but particularly here, Sussman was careful to include eraser marks, strikeouts, and additions, to show this uncertainty. She also wrote the timeline out by hand to personalize the experience. "To me that was saying, 'this is a human person trying to make sense of the universe,'" she said. "It's meant to show that it has a human author and that we're all trying to figure it out."
Sussman's process of trying to figure it all out began when she was working on a project photographing the oldest living things on Earth. The very oldest of these organisms, she said "started to get beyond geologic time and even into cosmic time," with things like stromatolites, mats of bacteria that can be as much as 3.5 billion years old, as you can see here.
She was also spending time embedded at space and physics outposts, including CERN, which runs the Large Hadron Collider. Among other questions the collider is tackling is what happened in the first few seconds after the Big Bang.
No one right answer
So when she decided to put together a timeline of the universe, she knew how to reach out to physicists to learn more. (She says Sean Carroll, a theoretical physicist at Cal Tech, was particularly helpful.) But these are not the sorts of question that have cut-and-dried right answers.
"This is obviously vetted scientific work, but I was able to choose the one that felt, 'oh, this is most conceptually resonant with me,'" said Sussman of using the theory of the five eras of the universe as the skeleton of her timeline.
According to this theory, we're currently in the universe's second era, the stelliferous era, a fancy name for a time when stars are still being created. The primordial era, from the Big Bang until matter began clumping together to form things like stars, is long gone. Down the road hundreds of trillions of years will come the degenerate era, after stars have run out of gas and dark matter is being destroyed. The fourth era will be dominated by black holes and in the last era, the dark era, there's nothing left but waste particles.
As to what made the cut into Sussman's timeline, "I really wanted to create a combination of things that are fascinating factually, but combined with a little bit of humor."
"I love when the Milky Way and Andromeda will collide but our solar system will survive," said Sussman of what may happen four billion years in the future. "I mean, of course we don't know that will actually happen." But it's a real possibility that our solar system could outlast our galaxy.
Others of Sussman's favorite entries include the first painting and the point in time 300,000 years after the Big Bang, when the universe is opaque because particles have been created but universe expansion has not yet spread them out.
You can visit the Massachusetts Museum of Contemporary Art to read through the entire timeline until April 2017.
So far, she said, visitor response has been mostly positive, with teachers telling her they plan to share the project with students. The museum did get one letter from a physicist, who wrote to tell Sussman she had a stray minus sign in the equation she used to represent Einstein's theory of general relativity.
But it's not that simple.
"Even the theory of general relativity, there's not one right way to write it out, which I hadn't known," Sussman said. It turns out there are three main versions, plus some others. She had physicist Sean Carroll talk her through the options.
He explained "'none of them were wrong but one of them was righter,'" Sussman said. "That's beyond me, how it could be right both with and without a minus sign."
But for Sussman, that's the point. "To me, all of this work opens up this reminder that there's so much that we don't know," she said. "When I think about how I was taught science as a child, I realized science is taught as facts, and it's really just how we think at the moment."
