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How heavy hydrogen reveals the dark Universe
Just by observing the tiny amount of deuterium left over from the Big Bang, we can determine that dark matter and dark energy must exist.
The Universe as we know it, at present, mostly adds up, but not in any sort of intuitive way. The 20th century brought with it the realization that the majority of what we know and experience in this physical Universe — atoms, light, and the known subatomic particles along with everything they combine to form — makes up only 5% of the total amount of stuff in the Universe. The remaining 95% is a mixture of things that are completely “dark” to us: dark matter, which gravitates, and dark energy, which drives the expanding Universe ever farther apart. Uncovering the nature of the dark Universe remains one of the most ambitious goals for 21st century science.
Our best evidence for the dark Universe comes from the combination of three different independent lines of observation:
- the cosmic microwave background,
- the large-scale clustering structure of the Universe,
- and the observed redshift-distance relation of objects, such as type Ia supernovae, at all cosmic distances.
