What could be at the “center” of the universe, the area where the Big Bang started?

This question is an erroneous assessment that many people make when conceptualizing the Big Bang. Colloquially, it is believed that the universe “began” with a “bang” or “explosion” from its primitive conditions, then expanded and cooled to its current state. A tempting image, but uncertain.

Let’s see why.

According to physics:

An explosion starts at one point, spewing material everywhere.

Faster moving material moves outward and therefore spreads faster. However, the further away such material is from the explosion, the smaller its range and energy density.

Consequently, no matter where you are, it will always be possible to deduce the center of an explosion from the amount of material present .

Graphic representation of a nuclear explosion.

This is not the case for the observable universe.

When this is studied at long and short distance, a certain “homogeneity” is presented in terms of the dispersion of matter; that is, it has equal densities, energies, and even galaxies. Likewise, distant objects that are moving away from us with greater speed appear to be younger compared to nearby bodies that are slowly receding.

But even more fascinating is the fact that, despite being able to appreciate universal movements tens of billions of light years away, the center of the Universe appears to be on Earth; ergo, humans are the center of everything.

Illustration of the Ptolemaic geocentric system by the Portuguese cosmographer and cartographer Bartolomeu Velho.

Does this mean that the Earth was at the center of the Big Bang?

Of course not!

This is because what is predicted by general relativity is not an explosion, but an expansion. We are told of a universe that begins from a state of high density and temperature, causing its own structure of space to expand.

Big Bang timeline infographic.

And said singularity did not occur at a single point. On the contrary, it arose in a region that had matter and energy, allowing the Universe to develop through the laws of gravity. This is the reason behind the equality of their properties.

Likewise, if we were able to look outside our Universe, we would see evidence of an evolving cosmos. This is because the Big Bang happened everywhere at once, in a finite amount of time in one region of space.

And all that we can see is shower region, from our limited point of view and where it seems that we are at the center.

Infographics of the epochs of cosmic evolution.

But this is a simple visual illusion, because the universe we know does not have a center.

What we understand as the region of space where the Big Bang occurred could be infinite. Otherwise, its center could be anywhere. Sadly, in order to predict where such a center is located we would need to know an “edge” and have a fundamental anisotropy [1] in temperatures and galaxy counts.

But this is not the case with our Universe, since, even on the largest scales, it looks the same in all directions.

Photograph of a celestial alignment on the Sicilian coast.