An Eventually Blank Sky: The Universe’s Expansion is Accelerating

While today humans have the awesome luxury of being able to look up at the skies and observe countless galaxies, planets, and stars, this won’t always be the case. One day, far away in the future, humans will look up at the night sky and see… only our galaxy. Is this groundbreaking astronomy we’re talking about? Absolutely. However, it’s groundbreaking astronomy that was fresh news in the latter years of the 1990’s. If you missed the newsflash, you’re not alone. The headlines are tremendously profound, and yet somehow managed to miss a majority of the public. The revelation is this: the universe is expanding, and the universe is expanding at faster and faster speeds.

 

Hold the Phone

In 1998 two completely separate labs studying the expansion of the universe reached the same conclusion simultaneously: that the universe’s expansion is accelerating. The Supernova Cosmology Project and the High-Z Supernova Search Team obtained evidence showing that rather than expanding at a steady or a decreasing rate, the universe was expanding more and more rapidly. This conclusion came as a complete shock, for it seems contrary to everything already understood about the universe and forces such as gravity. Imagine if you threw an apple up into the air and, instead of falling to the earth, it kept going and continually increased its speed. You’d be bewildered, right? As were the scientists who discovered that the universe was expanding faster and faster.

 

A Quick Look at the Science

The Supernova Cosmology Project and the High-Z Supernova Search Team used type Ia supernovas as “standard candles” to measure distances in distant galaxies. They found that the cosmic scale factor has a positive second derivative, meaning that the velocity at which a galaxy is receding from an observer is continuously increasing with time. Later evidence from other scientists such as that found in baryon acoustic oscillations and the clustering of galaxies has only confirmed, rather than refuted, what was originally found. Three members of the two aforementioned groups were awarded Nobel Prizes for their discovery, demonstrating the gravity (no pun intended) of their finding in the scientific world.

 

So… What Happens to Us?

Scientists aren’t sure. Fortunately, those of us experiencing the discovery as being “new” won’t have to worry about it in our lifetime. Nor will our children, grandchildren, great-grandchildren, and so on. However, when the generation comes who will have to worry about it, they may be dealing with an impossible and inevitable conclusion to the universe. Scientists speculate that one of the following may happen:

  • Big Freeze – Black holes dominate the universe and eventually themselves fade out
  • Big Rip – All material is disintegrated and the end state is a singularity
  • Big Crunch – All matter and space-time collapses into a dimensionless singularity
  • Big Bounce – The collapsing universe spawns another universe through a Big Bang-like event
  • Multiverse – This universe may reach a heat death, but other regions of the Whole Universe aren’t
  • False Vacuum – The universe splits into several new worlds

Don’t be too depressed. There’s also the option of “cosmic uncertainty,” which implies exactly what it seems to: we don’t really know all of what we’re talking about. There’s a strong chance scientists could be completely wrong about everything.

 

Think Happy Thoughts

Remember that all of this is science significantly dumbed down, and there is much to learn about each topic to fully grasp the gravity of the situation. Regardless, every human could mature a little as a result of learning that the universe is, effectively, going away. And it’s going away faster and faster. Enjoy the night skies while you can, as they won’t always be so lavishly filled with twinkling stars and swirling galaxies.