Big Problems with the Big Bang

The most common story of all Science classrooms, the story of us, and everything around us. The story starts 13.8 billion years back. Simply put, at first there was nothing, and then there was something.


Timeline of the metric expansion of space. Image by NASA via Wiki Commons.

First we see the four fundamental forces; gravity, electromagnetism and the weak and strong nuclear forces. Next we see a quark-gluon plasma soup, the ingredients are quarks, leptons and the antiparticles of the leptons. As the soup cools, hadrons are allowed to form, and baryons like our common neutron and proton start appearing. After 3 to 20 minutes of this story, the soup-universe becomes cool enough for fusion to occur, creating a few light elements. Skipping ahead a bit in the story, 560 million years to be exact, the first stars begin to shine and the rest of the story is our story.

While the specifics of time and particle names may not ring a bell, the idea of the Big Bang should as it is up there with God in the creation story genre. The Big Bang is more than a story however, it is a scientific theory. This means that it is not merely a speculative guess, but something that has withstood rigorous scrutiny.

Scientific theories are meant to be testable and able to make falsifiable predictions. Unfortunately, the Big Bang theory falls short on a few predictions and thus arises some problems that can’t be explained with this current theory.


The Horizon Problem

When you look into the night sky and see stars, the light you see is possibly hundred of years older than you are. All because the light that travels to you from the stars takes time to traverse the large distances and arrive at your eyes! Now thinking back to our hot soup of a universe in the first seconds after the Big Bang, in theory we should see the remnants of the heat that the soup-universe had. And we do! However if we look one way into the sky and detect this leftover heat, and then the opposite direction, we find that the heat signal is exactly the same! Even with 28 billion light years distance in between! The kicker here is that nothing can travel faster than the speed of light, but somehow these points separated by a distance, which could not be traversed in the time the Universe has existed, share the same signal. So why is the leftover heat the same in any direction we look?


The Flatness Problem

This issue actually deals with the shape of our Universe. There are three possible shapes our Universe could have.

Possible shapes of our universe. Image via Wiki Commons.


Closed Universe

There exists enough matter to allow the force of gravity to overcome the expansion rate, which is what Einstein theorized! Thus we would see something similar to a sphere shape.

Open Universe

The expansion of the universe is enough to overpower the force of gravity due to the amount of matter present, which will lead the universe to continue its expansion forever. Thus we would see a saddle-shaped Universe.

Flat universe

The expansion rate and the force of gravity are balanced to the point where the expansion rate will eventually slow down. Thus we would see a flat Universe!


In our findings though, we see that the universe is almost perfectly flat. After billions of years of the Universe existing, the likelihood of the balance between gravity and the expansion rate is so unlikely and “perfect” that the fact we even see this shape hasn’t been explained yet!


So what are we to do with these holes in our arguably most important theory? Do we dismiss it and find a new one? No of course not, we go further in attempt to solve these problems in the pursuit of knowledge. In fact, an ideal revolving around inflation is being studied currently to solve these exact problems!

6 Responses to “Big Problems with the Big Bang”

  1. Owen Stanley says:

    Hi Alex, love the images you used for the post!

  2. Alexander says:

    I see that currently cosmologists understand the universe is flat. But to me this is boring, I’d much rather the acceleration of expansion to slow down to allow for a “big crunch” where another big bang would occur. Something poetic about it I feel 🙂

  3. Alexander says:

    Hey Tyler, the omega is the density parameter. This is the ratio of observed density to critical density. Critical density being the density of the universe that is required to halt the expansion of the universe. Read more here!

  4. Ashley Densham says:

    Well played Alex, thanks for succinctly explaining the remaining gaps in the Big Bang theory. But please keep this article hidden from the creationists 😉

  5. Benjamin Andrikopoulos says:

    Wow this blew my mind! Such an interesting concept – which do you think is the most likely answer Alex?

  6. Tyler Sudholz says:

    Hi Alexander,
    What do the Omegas mean in the universe shape image?