Our Whole Universe Was In a Hot, Dense State

A quick science read to get the brain moving in tandem with your morning coffee: over at Medium, The Big Bang Wasn’t The Beginning, After All.

Space, time, and all the matter and energy within began from a singular point, and then expanded and cooled, giving rise over billions of years to the atoms, stars, galaxies, and clusters of galaxies spread out across the billions of light years that make up our observable Universe. It’s a compelling, beautiful picture that explains so much of what we see, from the present large-scale structure of the Universe’s two trillion galaxies to the leftover glow of radiation permeating all of existence. Unfortunately, it’s also wrong, and scientists have known this for almost 40 years.

“Great, so this is another topic where my physics teachers were just lying to me throughout school. Thanks, childhood.”

Anyway, tell us more!

[However, some] specific things you would expect from the Big Bang didn’t happen. In particular:

The Universe doesn’t have different temperatures in different directions, even though an area billions of light-years away in one direction never had time (since the Big Bang) to interact with or exchange information with an area billions of light-years in the opposite direction.

The Universe doesn’t have a measurable spatial curvature that’s different from zero, even though a Universe that’s perfectly spatially flat requires a perfect balance between the initial expansion and the matter-and-radiation density.

The Universe doesn’t have any leftover ultra-high-energy relics from the earliest times, even though the temperatures that would create these relics should have existed if the Universe were arbitrarily hot.

Theorists thinking about these problems started thinking of alternatives to a “singularity” to the Big Bang, and rather of what could recreate that hot, dense, expanding, cooling state while avoiding these problems. In December of 1979, Alan Guth hit upon a solution.

1979? Six years before I was born, we knew about this. I’m outraged. I won’t spoil the reveal, but go read the full article–it’s fascinating, slightly head-scratching stuff.