Cheap cosmology - the beginning

Cheap cosmology—the beginning

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How did the universe begin?

Be warned that current thinking on this issue is close to pure speculation.

Particle physics allows for quantum fluctuations, essentially somethings and anti-somethings appearing from nothing and then cancelling each other out almost instantaneously, with a nett effect of nothing.

Such a primordial blip might have involved the unravelling of a singularity. This singularity held within in it the four known forces, being the strong and weak forces, electromagnetism and gravity. Within an instant of non-time, gravity split from the other forces perhaps causing some kind of initial expansion and an instant later at 10^-36of the first second (as space and time began to mean something) the strong force split from the still combined electro-weak force. This was the point at which the first particles could appear—being the somethings and anti-somethings that might have cancelled each other out and returned everything to a state of nothing.

But not this time…

The persistence of the something which became the contents of the universe is said to be the result of a ‘violation of baryon number’, which just refers to an inexplicable inequity of early stuff and anti-stuff (maybe X and Y bosons?). This resulted in the persistence of some primordial ‘stuff’ that became the energy-matter contents of the universe as it is now. Throw in some terms like symmetry breaking and baryogenesis, add a bunch of Nobel prizes, and that’s pretty much the story.

The reason why the universe is so big is due to early inflation. It’s thought that as the forces split out from the primordial singularity, there was a huge release of quintessence, similar to the latent heat produced from a phase transition (like when liquid water freezes solid). This energy release caused space-time to expand at an incredible rate in a ridiculously short period between 10^-33 and 10^-32 of the first second. Inflation brought about the current shape of the universe, which is kind of flat and evenly spread out.

All these ‘something out of nothing’ processes that produced the big bang of expanding space-time—and the energy-matter within it—have led some cosmologists to call the universe the ultimate free lunch.

At about 400,000 years, electrons began to combine with nuclei forming the first atoms. This was a big event as space-time became transparent to electromagnetic radiation (photons) for the first time and the cosmic microwave background (CMB) radiation emerged, ending the need for any further speculation. We can still see the CMB today, which gives us an accurate picture of the state of the early universe at 400,000 years. The first stars lit at about 400 million years.

At a less well defined early point in time, it’s thought that dark matter coalesced into a kind of scaffolding upon which observable matter has been herded into the many galactic clusters which are observable today. It’s unclear how dark matter falls out of the above story, although some non-baryonic matter (e.g neutrinos) makes an appearance early in the first second.

With yet more ongoing expansion up to today, large voids of empty space-time between galactic clusters seem to be a source of dark energy (also known as vacuum energy). Dark energy is accelerating universal expansion—overcoming any slowing force that gravity (from light or dark matter) is able to exert. A big crunch seems unlikely if this phenomenon persists.

The universe cools as it expands which has presumably reduced the driving force behind early inflation and the gravitational effect of matter has further slowed the rate of expansion since.

At about 10^-6 of the first second, things get less speculative as more familiar particles like quarks and gluons (which can be produced in particle accelerators) began to appear.

The first baryonic matter (protons and neutrons) formed from them, but in particle and anti-particle form, leading to an annihilation of a huge proportion of both, but (a bit like the earlier baryogenesis phase), a slight proportion of particles persisted to form the universe’s contents as we now know it.

At about 3 minutes, nucleo-synthesis began, forming the first deuterium and helium nuclei—in addition to the already prevalent hydrogen nuclei (i.e. protons).

Current model of the evolution of the universe, using data collected by NASA’s WMAP spacecraft