Ars’ Edge of Knowledge series looks at important aspects of our Universe that we still understand poorly, like dark matter and the origin of life. This week, our host Paul Sutter bravely ventures into the area we probably understand the least: dark energy. Dark energy accounts for about 75 percent of the stuff in the Universe, but we still don’t have even the slightest idea what it is and are a bit stumped as to how to even go about finding out.
Paul goes into how we accidentally discovered that the Universe’s expansion is accelerating when astronomers looked for an indication that the expansion was slowing down. Dark energy is simply the term we’re using for the big unknown here: What’s driving that acceleration?
Unfortunately, as Paul describes it, all of the leading candidates we have are terrible in their own special way, and we don’t understand how to discriminate among them through observations anyway.
Despite being hard to pin down, Paul goes into why dark energy is now the dominant factor in our Universe’s evolution. And he spends some quality time with theoretical physicist Benjamin Wandelt, talking about how we might get a better grip on what dark energy is. For now, those mostly consist of observations of the Universe’s expansion at different scales and across different times to get a better sense of whether its influence has been a constant or a variable, and the size of structures that it has influenced.
There are still more Edge of Knowledge videos on the way, but we promise you that none will be edgier than this—dark energy really has a special combination of huge importance and near-complete ignorance.
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