In the beginning was the word and the word was “inflation”. That is no blasphemy. It is, rather, a celebration of human curiosity, ingenuity and bloody-minded persistence in the quest to try to find out how the universe actually works.
No one yet knows how the universe came into existence. Those who believe it was created by God are as free today as they were a week ago to continue in that belief, as are those who think the whole thing is the chance result of a quantum fluctuation in the nothingness beforehand. But results of a study of the early universe using BICEP2, a telescope located near the South Pole, where the air is thin and isolation keeps equipment clean, suggest what happened very shortly afterwards (see “Astrophysics: BICEP flexes its muscles”).
These findings, announced on March 17th, are of signs of primordial gravitational waves. They confirm the theory, debated among astrophysicists for three decades, that within a trillionth of a trillionth of a trillionth of a second of the moment it began the universe got bigger. Immensely bigger. A volume of space that started off no larger than an atom in the pre-inflation universe would, after inflation, have been about the size of the solar system.
Apart from the sheer gobsmackingness of this claim, the BICEP2 team’s discovery is important for three reasons. By confirming inflation it explains why the universe still exists–since it was inflation which stopped it fluctuating back into the void. By confirming the existence of gravitational waves, it bolsters Einstein’s general theory of relativity, which predicts them.
And by linking gravitational waves with inflation it provides a chink through which physicists can peer to try to solve one of their field’s biggest mysteries: why general relativity, which has passed every test applied to it, cannot be reconciled with quantum theory, which has also passed every test applied to it.
Quantum theory is the theory of small things. It describes electromagnetism and two less-familiar forces that operate at the scale of atomic nuclei. Relativity theory is the theory of big things. It describes the force of gravity. Since inflation is the way the universe made the transition from small to big, it is a good place to look for the missing link.
Not quite as simple as an apple and a persuasive serpent
The gravitational waves detected by BICEP2 date from the beginning of the inflationary process and are thus a product of the small, quantum-scale version of the universe. This means they are quantum phenomena–the first known manifestations of quantum gravity. That confirms the link between relativity and quantum theory (which no one really doubted). It also gives physicists investigating the link something real to play with in their search for how that link actually works.
A little caution is called for. It can be dangerous, in science, to put too much faith in a single set of observations. The gravity-wave signals that BICEP2 has found–slight fluctuations in the intensity of the cosmic microwave background, an all-pervading bath of radiation that preserves some features of the very early universe–are but a faded palimpsest. They have been overwritten time and again by other signals, and these have had to be scraped away to make the gravitational waves visible. Confirmation using other instruments is needed.
Other teams of scientists will now try to find similar evidence; new researchers will get excited about the field. This is welcome. The merging of particle physics and cosmology is one of the great intellectual achievements of the past 50 years. And in showing that the deepest truths of the material universe are to be found by gazing out into the deepest, earliest recesses of space, it feeds not just the intellect, but the spirit.
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