Some of the most extreme objects in the universe are also the densest. Just a teaspoon of a neutron star on Earth, for example, would weigh four times more than the entire human population.
Yet, the universe itself weighs practically nothing. That's because density depends not only on mass but also size, and the universe is, well, the largest thing known to humans.
Moreover, the universe is mostly empty space, so, despite the tremendously dense, heavy objects within it, the universe overall is extremely light. Just how much would a teaspoon of the universe weigh on Earth?
Here's how the answer compares with other common objects in space and on Earth:
Business Insider