“Science is not only compatible with spirituality; it is a profound source of spirituality. When we recognize our place in an immensity of light years and in the passage of ages, when we grasp the intricacy, beauty and subtlety of life, then that soaring feeling, that sense of elation and humility combined, is surely spiritual.” – Carl Sagan “The Demon-Haunted World.”
Learning about the Universe, I’ve felt spiritual moments, as Sagan describes them, as I better understand my connection to the wider everything. Like when I first learned that I was literally made of the ashes of the stars – the atoms in my body spread into the eternal ether by supernovae. Another spiritual moment was seeing this image for the first time:
One of the tenets of our cosmological model is that the universe is expanding. For reasons we still don’t fully understand, space itself is stretching over time. It’s a strange idea to wrap your head around, but the evidence for it is conclusive. It is not simply that galaxies appear to be moving away from us, as seen by their redshift. Distant galaxies also appear larger than they should due to cosmic expansion. They are also distributed in superclusters separated by large voids. Then there is the cosmic microwave background, where even its small fluctuations in temperature confirm cosmic expansion.
Weighing the universe is a tricky task, but a team of astronomers have used a clever technique to measure how many galaxy clusters are in the cosmos, and from there come up with a total amount of matter. The answer: 31.5±1.3% of all the energy in the universe.
Gravity is a strange thing. In our everyday lives, we think of it as a force. It pulls us to the Earth and holds planets in orbits around their stars. But gravity isn’t a force. It is a warping of space and time that bends the trajectory of objects. Throw a ball in deep space, and it moves in a straight line following Newton’s First Law of Motion. Throw the same ball near the Earth’s surface, and it follows a parabolic trajectory caused by Earth’s warping of spacetime around it.
In the beginning, the universe created three elements: hydrogen, helium, and lithium. There isn’t much you can do with these simple elements, other than to let gravity collapse them into stars, galaxies, and black holes. But stars have the power of alchemy. Within their hearts, they can fuse these elements into new ones. Carbon, nitrogen, oxygen, and others, all up to the heavy element of iron. When these first stars exploded, they scattered the new elements across the cosmos, creating planets, new stars, and even us.
How do you study something invisible? This is a challenge that faces astronomers who study dark matter. Although dark matter comprises 85% of all matter in the universe, it doesn’t interact with light. It can only be seen through the gravitational influence it has on light and other matter. To make matters worse, efforts to directly detect dark matter on Earth have been unsuccessful so far.
A supernova is a powerful event. For a brief moment in time, a star shines as bright as a galaxy, ripping itself apart in a last, desperate attempt to fight against its gravity. While we see supernovae as rare and wondrous things, they are quite common. Based on observations of isotopes in our galaxy, we know that about twenty supernovae occur in the Milky Way every thousand years. These brilliant cosmic flashes fill the universe with heavy elements, and their remnant dust makes up almost everything we see around us. But supernovae won’t keep happening forever. At some point in the far future, the universe will see the last supernova.
In the 1920s, Edwin Hubble studied hundreds of galaxies. He found that they tended to fall into a few broad types. Some contained elegant spirals of bright stars, while others were spherical or elliptical with little or no internal structure. In 1926 he developed a classification scheme for galaxies, now known as Hubble’s Tuning Fork.
When you look at Hubble’s scheme, it suggests an evolution of galaxies, beginning as an elliptical galaxy, then flattening and shifting into a spiral galaxy. While many saw this as a reasonable model, Hubble cautioned against jumping to conclusions. We now know ellipticals do not evolve into spirals, and the evolution of galaxies is complex. But Hubble’s scheme marks the beginning of the attempt to understand how galaxies grow, live, and die.
Back in 2015, construction began on a new telescope called the Dark Energy Spectroscopic Instrument (DESI). Later this year, it will begin its five-year mission. Its goal? To create a 3D map of the Universe with unprecedented detail, showing the distribution of matter.
That detailed map will allow astronomers to investigate important aspects of cosmology, including dark energy and its role in the expansion of the Universe.
If you look out on the sky on a nice clear dark night, you’ll see thousands of intense points of light. Those stars are incredibly far away, but bright enough to be seen with the naked eye from that great distance – a considerable feat. But what you don’t see are all the small stars, the red dwarfs, too small and dim to be seen at those same distances.