For a century, the Big Bang has been a big subject. And why? Well it’s know to be the reason where’re all here today. It wasn’t an explosion somewhere in space; it was the expansion of the whole space. Today, new questions are back in the scene: how did the primitive universe get so big so fast, and why is the actual expansion accelerating? Was that beginning the real start of it all?
To get these answers, and more, cosmology leans on the Cosmic Microwave Background (CMB)—what’s left of the universe when it was about 380.000 years old—and 3D maps of galaxies like the Dark Energy Spectroscopic Instrument (DESI).
To explain the ultrafast initial expansion, the theory of cosmic inflation comes to place, even though how it works is still not very clear. A team from the University of Portsmouth, led by Enrique Gaztañaga, gives another alternative: a bounce universe, created by the matter collapse in a bigger cosmos, then formed into a huge black hole, where the quantum effects could’ve stopped the singularity and unleashed the expansion. If this clue is right, the CMB patterns and the galaxies distributions should preserve the bounce’s footprints.
Missions like ESA Euclid and proposals like ARRAKIHS promise to refine the map and to look deeper into both theories.
Expansion, maps, and enigma
In the standard frame, the universe reached extreme densities and temperatures. So to explain the early growing and uniformity observed in the CMB, scientists added the cosmic inflation theory, a very fast expansion episode. And yet, there are some holes: this model tracks back to an effectively infinite density, a region where “physical science” starts getting off signal. Some maps help get together some pieces.
CMB has a baby picture of the universe; the 3D DESI catalogs show how galaxies assembled together later. They both are sensible of dark energy, which is responsible for the actual acceleration. Together, they back up the Big Bang frame as a space expansion, and at the same time it raises questions about the unknown, the secret dynamic that runs the universe.
The Portsmouth alternative
The team from the University of Portsmouth proposes that the Big Bang was not the beginning. In their theory, matter collapsed inside a bigger universe until forming a huge black hole. The quantum effects would have stopped the singularity, giving space to a bounce universe that “burst” in expansion. With this, the ultrafast growth could be explained without relying on cosmic inflation. And besides, the scheme would be compatible with the actual acceleration attributed to dark energy.
In this vision, the maps are a critical tool: if the bounce happened, it should be reflected in the position of the galaxies, as much as in the little waves recorded on the CMB.
ESA Euclid and ARRAKIHS: Missions and predictions
Testing rival theories demands data from the relics and better maps. This is where ESA Euclid and ARRAKIHS come in; these should refine the register and structure to a bigger scale to give a clearer lecture of the past universe.
What’s the method? To confront each model’s predictions: inflation cosmic theories and the bounce universe, with the pattern observed in the CMB and the 3D images from DESI. So this way, this is not a debate but a contrast exercise. Science’s strength has always been to challenge their best ideas while letting the cosmos speak.
Exploring where it all beganb is not so much about defending a doctrine as it is about looking at the evidence. If the verdict favors the traditional Big Bang or the bounce universe theories from Portsmouth, will be told by the footprints that are already in the sky, waiting to be read by more precise tools.