The Big Bang theory is well established in the scientific community to explain the initial point at which matter, space and time were formed. This explosion, which occurred about 13.8 billion years ago, consisted of a rapid energy inflation at a very high temperature and density that later led to a cooling that allowed the formation of the first subatomic particles that formed matter and reality. However, a new study now calls this hypothesis into question.
“Inflation was theorized to explain various tuning challenges of the so-called hot Big Bang model,” Dr Sunny Vagnozzi of the Kavli Institute for Cosmology in Cambridge and the paper’s first author said in a statement. “However, the great flexibility shown by possible models of cosmic inflation that cover an unlimited panorama of cosmological results generates concerns that cosmic inflation is not falsifiable, even if individual inflationary models can be ruled out. Is it possible, in principle, to test cosmic inflation in a model-independent way?
Inflation in question
When the Planck satellite published its first measurements of the cosmic microwave background (CMB), the oldest light in the universe, in 2013, some scientists worried about cosmic inflation. Although these results were presented as a confirmation of it, many experts, as Vagnozzi says, argued that it could be exhibiting just the opposite.
Along with Anna Ijjas and Paul Steinhardt, Professor Avi Loeb was one of those who argued that Planck’s results showed that Inflation posed more puzzles than it solved, and that it was time to consider new ideas about the beginnings of the universe, which, for example, may have started not with a bang, but with a rebound.
The authors propose the Big Bounce (big bounce) as an alternative claiming that the universe is the result of the end of one cosmological phase and the beginning of another, of a rebound from a previously contracting cosmos. This contradicts the Big Bang theory, which admits that before that explosion nothing existed.
The study proposes an experiment to detect the background of primordial gravitons that demonstrates that the Big Bounce It may be the explanation for the origin of our universe, its nature and what would have existed before.
“The actual edge of the observable universe is as far away as any signal could have traveled at the speed of light limit during the 13.8 billion years since the birth of the Universe,” Loeb said. “As a result of the expansion of the universe, this edge is currently at 46.5 billion light years away. The spherical volume within this boundary is like an archaeological dig centered on us: the deeper we probe it, the earlier the layer of cosmic history we uncover, all the way back to the Big Bang that represents our latest horizon. What lies beyond the horizon is unknown.
The neutrino study, which are nearly weightless particles and the most abundant with mass in the universe, could make it easier to delve even deeper into the early cosmos. “The current universe must be full of relic neutrinos from that time,” Vagnozzi said. However, Vagnozzi and Loeb comment that we can go even further back by tracing the gravitonswhich are particles that mediate the force of gravity.
The scientists pointed out that the universe was transparent to gravitons from the first instant tracked by known physics: once the gravitons traveled freely without scattering, a “relic” background should have been generated from this initial radiation, an equivalent to the cosmic background of microwave but applied to these particles: the CGB.
But the Big Bang theory does not allow the existence of the CGB, since it suggests that the exponential inflation of the newborn universe diluted relics like this. Therefore, if CGB is detected cosmic inflation would be ruled out, which does not allow its existence. Vagnozzi and Loeb believe such a test is possible and adds to the cosmic radiation budget, which otherwise includes neutrino and microwave backgrounds. The problem would be that this would be very difficult to detect and would require tremendous technological advances in superconducting magnet and gyrotron technology. Something that, they say, will come in the coming years.