Matter can be neither created nor destroyed. This is one of the fundamental laws that hold the universe in balance. It is how the atoms and smaller bits in your hands and chair and the sun have been in existence for more than 13 billion years. Of course, energy also can neither be created nor destroyed, but matter itself is simply energy in another form. So you, and your atoms and smaller bits, are part of a universe that started with all the same materials it has now, just in slightly different forms. A natural thought might be bent toward what will become of these bits as the universe carries on without you. 

In a little over 4 billion years, the sun will balloon to more than 100 times its current size. Mercury and Venus, the innermost planets, will undoubtedly be swallowed by the expanding red giant. If Earth escapes destruction, we will still suffer a harsh broiling. Much of the surface will be stripped away: its atmosphere, water and the rest. 

Eventually, the dying sun will expand too far and lose its grip on the outermost wisps of its atmosphere. The gas will have puffed far out into interstellar space, enriched by the stripped materials of planets and the heavy elements created in the star. 

Don’t be worried. You’re still featured in the story. You’re the heavy elements from the earth, as elements above helium are “heavy” and considered metals. The you-enriched nebula will, with time and some nudging by supernovae, coalesce into a new star. In fact, it is from such a cloud that the sun formed. Every time a star dies, its last exhalations give back to the interstellar medium and are used in stellar generations to come. It appears the atoms and energy are all accounted for in the stellar recycling, continuing our story forever.

Looking a little below the Great Square of Pegasus (unfortunately close to the sun in springtime), one can see the smudge of a smudge next to a chain of stars. That is the galaxy Andromeda. To the naked eye, our nearest neighbor appears as the fuzzy, distant light of many stars. With the appropriate telescope, one can see that this giant spiral is heading toward us — at a speed of about 70 miles per second. 

Even at that speed, it will take 4 billion years to cross the many lightyears between us. Slowly, then, the galaxies will dance around one another, halted by friction between their gases, finally settling into a single, giant elliptical galaxy. The gases, heated and perturbed, will be flung from the system or captured by any of the trillion stars moving about. That is where our story ends. 

A new star cannot form without a gas cloud collapsing upon itself, heating up and igniting. Planets form from the pebbles and dust in the leftovers. With any luck, some of that dust is the same carbon and nitrogen that was in our cells. However, as the sun flings its gas out of the solar system, the gas is then ripped away in the galactic merger. It will float undisturbed for ages.

There is a happier ending. Before getting ejected, the gas has to get through the mixing of both galaxies. In all that mess, there can be a burst of star formation: planetary bits from different galaxies, smashing into one another to create the final stellar systems.

So our atomic journey may not end, stranded in the intergalactic void. It may be among the last stars of an active galaxy, simply watching the lights turn on.

Ethan Gower is a senior studying astrophysics and geology at Ohio University. Please note that the views and opinions of the columnists do not reflect those of The Post. What do you think about climate change? Let Ethan know by emailing him at eg662511@ohio.edu.