How is this acceleration possible?
There’s still a lot we don’t know about our universe. With the amount of gravity we can measure, it seemed like the expansion of the universe might slow, might stop, or might even even- tually cause the universe to collapse back in on itself. We can now observe that none of these are true, but, we don’t exactly know why that is.
The most common working theory is that our universe is composed of a substantial amount of mysterious constituents that we did not even consider decades ago. In fact, only 4 percent of the universe appears to be made up of “normal” matter, the “stuff” of trees, planets and us, which we can observe. The rest—96 per- cent—may be made up of what we call Dark Energy and Dark Matter.
What are Dark Energy and Dark Matter?
Both are called “Dark” because they cannot be seen and are certainly not easily detected. Dark Energy would be what is propelling objects in the universe outward against the attrac- tion of gravity. Dark Matter would explain why parts of galaxies rotate at speeds far greater than expected. But we cannot concretely say at this point anything about the intrinsic characteristics of either of these.
What does it all mean?
As best as we can tell, it means that everything in the universe is moving away from everything else, and ac- celerating as it does so. Eventually, the universe may just sort of fizzle out.
Should I find this upsetting?
I don’t think so. For one thing, this “fizzling out” is probably a trillion years in the future. Our star, the Sun, will have expanded and destroyed the Earth in 5 billion years anyway. But far more importantly, it’s exciting to watch the scientific method uncover unexpected truths. Our universe is more wondrous and complicated than we can imagine. And I, for one, am glad to have more to learn.
SPRING 2013
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