The universe emerged 13.8 billion years ago. What happened in that initial moment is of great interest to anyone trying to understand why everything is the way it is today.
“I think this question of what happens at the beginning of the universe is profound,” said David Spergel, president of the Simons Foundation, a nonprofit that supports research at the frontiers of mathematics and science.
A new $110 million observatory in northern Chile, with $90 million in funding from the foundation, could uncover key clues about what happened after the Big Bang by observing particles of light that have traveled through the universe. since almost the dawn of time.
The data could finally provide compelling corroboration—or undermine—a fantastical idea known as cosmic inflation. He argues that in the first fraction of time after the birth of the universe, the fabric of space-time accelerated outward at speeds much faster than the speed of light. This hypothesis is a pillar in the current understanding of cosmology.
Located in the middle of an arid landscape at an altitude of about 5,200 meters, the Simons Observatory has three small telescopes and one larger one that consists of a pointable box. Two of the smaller telescopes are collecting data now, the third will join in a few months, and the largest will begin next year.
Then, some 60,000 detectors on the four telescopes will study the cosmic glow of microwaves—wavelengths longer than visible light, but shorter than radio waves. In particular, the observatory aims to study B modes, swirling patterns of polarized light in microwaves.
During the first 380,000 years of the universe’s infancy, temperatures were so high that hydrogen atoms could not form, and photons — particles of light — bounced off charged particles, absorbed and emitted continuously. But as soon as hydrogen could form, the photons could travel unimpeded. Photons have cooled to a few degrees above absolute zero and their wavelengths have extended into the microwave part of the spectrum.
Alan Guth, a professor at the Massachusetts Institute of Technology (MIT), proposed the idea of cosmic inflation 45 years ago, in part to explain the homogeneity of the universe.
The observable universe is so large that there is not enough time for a photon to travel through it to equalize temperatures everywhere. But a rapid stretching of space-time—inflation—could have done it. It would have ended when the universe was less than a trillionth of a billionth of a billionth of a second.
The accelerated expansion would have generated titanic gravitational waves that would have pushed matter in a way that would have imprinted B modes among the primordial microwave radiation.
Observatory scientists will examine polarization, a property of light. Light is made up of electric and magnetic fields that oscillate at right angles to each other. Normally, these fields are oriented in random directions, but when light reflects off certain surfaces, the fields can align, or become polarized. Polarization can be studied with a filter, through which only the part of the light polarized in a certain direction will pass.
There are two types of polarization patterns. One of them is called E mode, which means electric, because it is analogous to the electric fields emanating from a charged particle. Previous observations have detected E modes in primordial microwaves, generated by variations in the density of the universe.
The other pattern has a characteristic found in magnetic fields. Physics uses the letter B to designate magnetic fields, which is why it is known as B mode.
Gravitational waves would have shaken the electrons so that they generated tiny B modes in cosmic microwaves.
If the observatory detects no B mode, that would not definitively disprove cosmic inflation. But it would make it more difficult to twist theoretical models in ways that produce B modes small enough not to be detectable.
“The inflationary paradigm is going to be in big trouble,” said Gregory Gabadadze, senior vice president of the Simons Foundation. “The majority will abandon it and we will be looking for alternatives to inflation.”
#spacetime #accelerate #Big #Bang #search #waves #space #advances