Why Do the Laws of Physics Fail at the Singularity
Origin of the universe and mystery of gravitational singularities
The beginning of the Universe was a huge question in the scientific community in the early 20th century until a Belgian physicist and priest Georges Lemaitre came into the field and provided the most consistent explanation regarding the beginning of the universe famously known as the Big Bang. Unlike its name, the big bang wasn’t really a bang. There was no explosion that happened. It was merely an expansion of space. After one million trillion trillion trillionths of a second, the so-called bang had a phase called the Planck phase, the physical theories of the known universe didn’t work but we’ll come to that part in a while. Let’s try and understand the period after the Plank epoch first. Hypothetically, during the earliest phase of the big bang, the known fundamental forces of nature were combined into one force (except gravity).
Then started the inflationary phase, where the universe started to expand in an exponential manner. It is nearly incomprehensible to understand the estimation of the expansion of the space between 10–36 to 10–32 seconds of the big bang. It was at this instant when the strong interaction got distinct from the remaining three fundamental forces and what remained was a space with high energy density, with electroweak interactions. Electroweak interactions mean the combined form of electromagnetic and weak nuclear forces. With, expansion the temperature of the Universe cooled down and reached enough for the formation of quark-gluon plasma. Up to the first second of the big bang, the universe had seen the formation of hadrons by the combination of Quarks. It was around this phase when particles and their anti-particles annihilated forming matter universe only. It is estimated that for every one billion and one matter particles, there were one billion anti-matter particles and from that extra matter, particles created all the matter of the universe that we see today. In cosmology, it is called the baryonic asymmetry or the process of baryogenesis and it is still one of the most important unsolved problems in physics.
Maybe we have another Universe that is entirely made of anti-matter particles. The laws of physics keep demanding the theory of multiple universes in several instances. Coming back to the big bang, the nucleosynthesis era started when protons and neutrons bound together forming the first nuclei of an atom namely hydrogen, helium-4, etc. The universe is opaque so far as the temperature is too high for electrons to bind with the nuclei and there are no free photonic particles. The photons, during this phase of the early universe, were in thermal equilibrium with the matter particles. The universe expanded further and cooled down. When the universe was around three hundred and eighty thousand years old, the recombination era took place when the conditions were suitable enough for electrons to combine with the nuclei and form neutral atoms. It was during this phase, that the Cosmic Microwave Background radiation was emitted. The CMBR is one of the most powerful pieces of evidence for the big bang theory of the origin of the universe.
There’s an extremely fascinating story behind the discovery of cosmic microwave background radiation. It was an accidental discovery and one of the most profound ones in the history of astrophysics and cosmology. Robert In 1964, Robert Wilson and Arno Penzias thought the unexpected noises in their receiver were the result of pigeon droppings, and the duo of scientists spent hours cleaning the pigeon dung. Fortunately, the noises persistently kept knocking, and after the joint analysis of astrophysicists at Princeton including Bob Dicke, Jim Peebles, David Wilkinson, and the Bell Labs duo, Penzias and Wilson, the discovery of the CMB was confirmed. The theoretical prediction of the radiation by the Princeton team became consistent with the data received by the scientists at the Bell Labs resulting in an iconic scientific discovery. The analysis of CMB radiation played a great role in determining the conditions of the early universe including the composition, and the age. The 2013 data sent by the Planck Satellite (launched in 2009) helped us find more information about the content of dark matter and dark energy.
Most phases of the early universe are comprehensible and can be understood by using the laws of physics. From the formation of the first quark to the recombination era and production of the cosmic microwave background radiation, things fit pretty well with the experimental data and calculated speculations. What we do not understand clearly, however, is that dense form of matter where the laws of physics break down. In scientific terms, it is called a gravitational singularity. A similar condition can be found at the center of a black hole where the matter is so dense that even light cannot escape from it. The laws of physics break down in these regions of space because we have understood gravity with regard to Einstein's general theory of relativity, and when the mathematics is done for these regions, the equations just break down. The solutions become somehow incomplete.
Gravitational singularities are the only places in space, so far known, where the two major foundations of modern physics seem to combine: the general theory of relativity and quantum mechanics. However complicated the mathematical solutions for such reasons is, they can be a great source for studying and maybe finding a unified theory of everything. For several decades, physicists and cosmologists have been trying to unify quantum mechanics with general relativity but in no vain. Sometimes the mathematics doesn't fit well and sometimes the experimental data required by the theory becomes nearly impossible to gain with the technology we have today. The most promising theories of gravity that we have developed so far are superstring theory and loop quantum gravity. But these theories have their own limitations. Perhaps, a full-fledged theory of quantum gravity could help us understand the most mysterious parts of the universe.
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