Our universe is where forces of fantastic power wage an eternal war to either crush all of creation to the size of a tennis ball or rip us apart and spread us to the far corners of infinity. And it’s all happening right before your eyes.
According to the Hobby-Eberly Telescope Dark Energy Experiment, dark energy makes up 74 percent of the known universe, dark matter makes 21 percent. That leaves about 4 percent of the universe for things like stars, planets and cats, and a mystery 1 percent that scientists are reserving for all manner of minutia not included in the study.
So with dark matter, and especially dark energy, comprising a resounding majority of all known things, what do we know about them?
Physicist Leonard Susskind has said that dark matter is “not mysterious at all.” He goes on to say that dark matter is “like neutrinos” in that they are smaller than atoms and, as such, are difficult to detect, but certainly are present. Feel like you understand yet? Welcome to theoretical astrophysics.
It’s difficult to say what things like dark matter and dark energy are because they are, by definition, dark, meaning that they are not in the form of the stars, planets and cats that we can see. All we know of dark matter and dark energy is derived from their observable influence.
We know that while dark energy repels, dark matter attracts.
If our basic understanding of gravity is correct, the center of our spiral galaxy, where it is most dense, should spin much faster than the ends of its outstretched arms, where the stars are much scarcer.
However, this is not the case. We’ve measured that all parts of our galaxy spin at roughly the same speed. Witchcraft!
A scientist looks at this and asks, “What could be the cause of this?” The answer generally is held to be the existence of a great force lingering in a great halo around the entire galaxy exerting an opposing gravitational force on the Milky Way, and as such countering the tremendous gravity of the galaxy’s core.
Still with me? We know the dark matter exists, because something must exist to counter the core’s gravity, and there would need to be a lot of it.
Dark energy is a different animal entirely. Completely unrelated to dark matter except that it is also invisible, dark energy is intent on repelling the universe into oblivion. Simply put, it is a known fact that the universe is expanding and a recently known fact that it is expanding at an increasing rate.
What we do not know is why. Hence, the invention of dark energy, that immeasurably prevalent force driving the edges of space further and further apart from one another, and creating more space (and more dark energy) in the process.
Again, with dark forces, our only true source of information lies in their observable effects.
A bump in the night, known by the bump.
Hundley is a Richmond Hill High School graduate who will begin teaching high school science next school year in Charlotte, N.C.