What the hell are Baryon Acoustic Oscillations?
They’re our best measurement of dark energy, even better than supernovae!
“If you think this Universe is bad, you should see some of the others.”
-Philip K. Dick
Imagine you’re looking out at the Universe, at all the points of light that are out there — planets, stars, galaxies, clusters of galaxies and more — and you want to use what you’re seeing to measure how the Universe is expanding. Not only how it’s expanding today, but how it was expanding at every moment in the past, from as far back in time as we can measure until now.
How would you do it?
Every object that’s out there has a number of properties that are intrinsic to it: physical traits of the object itself. These include:
- its mass,
- its size,
- and its luminosity (or intrinsic brightness).
If our instruments are good enough, we can measure an object’s apparent size or its apparent brightness directly: how big or how bright it appears to be from our vantage point on Earth.
