Banner by Emma Tristano

How Looking Back in Time Can Explain the Future

By Ariel Barreiro

An ancient, white-haired man stands in his backyard on a clear night, hunched over with his eye to the aperture of a telescope, peering out at the dark sky. This is the cartoon caricature of the astronomer — the accepted Western version. In reality, astronomers are of all persuasions. These days, they rarely physically look through telescopes. The stereotypical ideas of how we acquire the stunning images that fascinate us about what could lie beyond our tiny planet are outdated at this stage in humanity’s technological development. 

The backyard telescope pales in comparison to NASA’s most recent marvel, the James Webb Telescope. The James Webb Telescope, or JWST, is the size of a small bus now that it has been unfurled in space. Shot 1.5 million km (or just under one million miles) to a point known as Lagrange Point 2, it is NASA’s most expensive and time-consuming —  taking over 30 years to build —  telescope to date. 

The engineering had to be flawless, from its blueprint to its implementation, for this project to work. The design is still top secret in some respects, with spacecraft company Ball Aerospace having a proprietary handle on the specific instruments that brought the telescope to space. These devices are able to  knock the mirrors next to each other at a tenth of a nanometer of distance: which is “significantly less than the width of a strand of hair.” It is worth noting that with a final cost of $10 billion, it is “still less than the price of an aircraft carrier.”

Launching an instrument like this in our current socio-political climate has, of course, garnered the questions – is it worth it, and why? The questions of why, and how, is exactly what JWST aims to answer. Scientists are often credited with a mindset similar to those of Jurassic Park, which famously states that they “were so preoccupied with whether they could, they never stopped to think if they should.” However, JWST falls into a category of its own.

Its predecessor, The Hubble Telescope, was first launched in 1990 after a similar slew of financial and engineering difficulties. Its most notable return, the Hubble Deep Field Image, brought forth more questions than answers. After 100 hours of exposure in what we thought was an empty part of space no bigger than a sliver of moon, Hubble unearthed thousands of galaxies and undid several popular theories regarding space expansion. Hubble revealed that our solar system was atypical; it provided more evidence that dark matter and energy must be prevalent, and that black holes widely exist.

JWST may answer a plethora of questions, known as a treasury program, like is there alien life on other planets? How were the first galaxies formed and what were they made of? What is the rate of expansion of the universe and where is its beginning? Or better yet, is there a beginning? While the Big Bang Theory is the most widely accepted theory among astronomers, it is still just a theory.

So, how can JWST identify alien life? Astrobiologists will measure the atmospheric accumulation of “biosignature gasses,” which are gasses that only arise if life is present on a planet. We interpret light and color through wavelengths, and starlight has a distinctive array of colors. A planet’s atmosphere will absorb some of those colors, and JWST will see what colors are missing, thus allowing astronomers to determine the composition of these exoplanet atmospheres and if it correlates with biosignature gasses.

Perhaps the most mind-bending concept of JWST’s capabilities is that of looking back in time. Backwards time travel is not possible according to modern physics, so how can we look back in time? What does that mean? There is a substantial amount of math involved, but it can be broken down into simpler terms 

A well-known fact is that if the Sun were to explode, it would take eight minutes for us to see it on Earth. This is because of the way light travels; the speed of light is 300,000 km/s or, for us Americans, roughly 669,600,000 miles/hour. This means that, as we look into the sky, we are seeing things as they were, not as they are. All that we see is made up of light waves, and because these light waves must travel to our eyes in order to see them, when we look farther and farther away, we are looking into the past. The general conclusion is that the farther objects are, the more likely it is that they do not exist anymore. Keep in mind, too, that light years, hours, and seconds are not measurements of time, but rather, distance. One light year is 5.9 trillion miles away, which is 12 zeros added to the end of that 5.9. To highlight this vast distance, consider that the University of Pittsburgh to Market Square downtown is three miles, and the Earth itself is about 25,000 miles around the equator. The Sun is 93 million miles, or .000001 light years away from us, and takes eight minutes for its light to travel to us. The nearest star, Proxima Centauri, is 4.2 light years away, which means its light  requires about 51 months to reach us on Earth. So, the light from objects billions of light years away can take billions upon billions of years to get here.

Now, let’s add in the expansion of space. The best way to describe the expansion is to think of a balloon covered in pennies. At first, the balloon is not inflated. As you begin to inflate the balloon, the pennies all move away from each other, but they are not actively receding from each other; the balloon is simply expanding. That is the understanding of our universe. It is easy, in the eye of the mind, to picture space as a linear entity, especially considering that we tend to draw in 2D. We are not at the center of our universe as far as we know, meaning space has expanded in every direction around us and around every object for 13.8 billion years, making it 46 billion light years across.

Let us turn our thoughts to looking back in time - now that we have a very basic understanding of what that means - to the first galaxies. Pitt’s very own associate professor in the Department of Physics and Astronomy, Dr. Rachel Bezanson, is a part of three out of 266 accepted projects for the JWST, and is leading one called “UNCOVER.” The project’s primary focus is to gaze back and find the earliest perceivable galaxies so that they can analyze their composition and formation using an ultra-deep imaging and spectroscopic survey, “deep” meaning it will be exposed for a long time and to faint depths. “Very early on in the observations, we’ll stare at a field of sky —  one of the deepest field projects to happen in the first year — for about 30 hours with different filters (wavelengths), pick our favorite few hundred objects, then eight months later, use a different instrument to analyze the same patch,” she explains.

Bezanson says this project will answer a few questions about early galaxies: Are they as distant as we think, what were they made from, and how rapidly did they form? Right now, astronomers do not understand much about early galaxy or star formation. Everything we know about stars relies on the fact that they are made of metal, but it seems the first stars were not. She says there is a concern they will not be able to see anything, but that is why they will stare for such an extended period of time at the same spot, similar to how the Hubble Deep Field image was achieved.

Another misconception about JWST’s abilities is the idea of seeing back to the Big Bang. Bezanson clarified that may never happen and that the farthest we could see would be the cosmic microwave background, or the CMB. The CMB is “the equivalent of a very cloudy day in Pittsburgh and you just can’t see the sun. But there should be a moment when those first-generation stars push a hole through those clouds.” This period is referred to as the Cosmic Dark Ages and ends about 500 million years after the Big Bang. “And that’s what we think we can see back to, you know plus or minus 200 million years – but what’s that amongst friends?”

NASA’s research and development (R&D) in areas such as JWST has created a good deal of the comforts of our everyday lives. Early spacecraft technology gave way to the cell phones we have today, created applications like GPS, and provided advancements in water filtration, to name just a few. NASA ensures that these “alternative applications, or spinoffs, are made available to the public.” Imagine the possibilities when the nanotechnology Ball Aerospace created for JWST becomes public!

On the other side of the philosophical coin, our propensity to question our existence is a reason to invest in telescopes. Entire civilizations have come to be and ultimately ended over the ideologies of our creation and what our purpose might be. Religious texts and telescopes are asking and attempting to answer the same questions —  simply different methodologies. 

A clump of dust rolls across the floor like a miniature tumbleweed. Inside it are a million specks of dust. We are a speck to our Earth, our Earth a speck to the Milky Way, the Milky Way a mote to the surrounding Universe; like Russian nesting dolls of microscopic universes the further out one travels. Why are we here and how did we get here? The answer might be as depressing as random chaos and natural selection, or it could be as interesting as random chaos and natural selection. It is the perception of the viewer, as physics teaches us time and time again.