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A Big Problem With the Big Bang
The universe has a lithium problem.
Within a few minutes after the Big Bang, the hot soup of the nascent universe expanded and cooled enough to form hydrogen and helium, the simplest elements on the periodic table. Our best models predict that the early universe was roughly 75% hydrogen and 25% helium, with trace amounts of heavier elements. This matches current observations, except for the fact that we should be able to detect three times more lithium than we do.
Known as the cosmological lithium problem, this inconsistency raises some concerning questions about the early universe.
How Hubble Changed the Game
In 1923, Edwin Hubble sat in the Mount Wilson Observatory and pointed the 100 inch Hooker Telescope at a fuzzy patch in the sky called the Andromeda Nebula. Astronomers believed this was merely a collection of hot gas and dust. Hubble, though, used the telescope to resolve distinct stars, providing the first strong evidence that this cloud was, in fact, a separate galaxy.
And Hubble kept going. He found a Cepheid variable star within Andromeda. These stars, known as standard candles, have cyclical brightness, making them useful for measuring distances in space. The period of their brightness cycle is directly related to their intrinsic…
