The universe was born 13.8 billion years ago. What happened in that first moment is of great interest to anyone trying to understand why everything is the way it is today.
“I think the 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. “And what's extraordinarily exciting to me is the fact that we can make observations that can give us insight into this.”
A new $110 million observatory in the high desert of northern Chile, funded by the foundation to the tune of $90 million, could uncover key clues about what happened after the Big Bang by observing particles of light that have traveled across the universe since almost the beginning of time.
The data may finally provide compelling confirmation of a fantastic idea known as cosmic inflation. It is believed that in the first fragment of time after the birth of the universe, the fabric of space-time accelerated outward at speeds much faster than the speed of light.
Alternatively, observatory measurements could undermine this hypothesis, a mainstay in current understanding of cosmology.
The observatory is named for the foundation and its founders: Jim Simons, the hedge fund billionaire and philanthropist who died on May 10, and his wife Marilyn, an economist by training. Two of the four telescopes began taking measurements in April, in time for Dr. Simons' 86th birthday on April 25.
“This was kind of a goal that Jim had set a long time ago for completing the project,” Dr. said. Spergel. “And we got there.”
Perched in a majestically barren landscape at an altitude of 17,000 feet, the observatory has three small telescopes that vaguely resemble ice cream cones and a larger one that consists of a spiky box, something of a “Star Wars” cousin. droid.
Telescopes collect microwaves, wavelengths longer than visible light but shorter than radio waves. Two of the smaller telescopes are already collecting data. The third will join in a few months, while the fourth, much larger one, will come online next year.
Around 60,000 detectors across the four telescopes will then study the cosmic glow of microwaves filling the universe.
“It's a unique instrument,” said Suzanne Staggs, a physics professor at Princeton University and co-director of the Simons Observatory. “We have so many detectors.”
For 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 the charged particles, continually being absorbed and emitted. But as soon as hydrogen was formed, photons were able to travel unhindered. The photons cooled to a few degrees above absolute zero and their wavelengths stretched into the microwave part of the spectrum.
The cosmic microwave background was first observed half a century ago, a fortuitous hiss picked up by an antenna in Holmdel, NJ
In the 1990s, a NASA satellite, the Cosmic Background Explorer, revealed tiny temperature ripples within cosmic microwaves — fingerprints that indicate what the early universe looked like. The fluctuations reflected changes in the density of the universe, and denser regions would later merge into even larger galaxies and structures of superclusters of galaxies aligned like a cosmic spiderweb.
The Simons Observatory aims to reveal even more details – swirling patterns of polarized light that cosmologists call B-modes – in microwaves.
Alan Guth, a professor at the Massachusetts Institute of Technology, proposed the idea of cosmic inflation 45 years ago, partly to explain the bland homogeneity of the universe. No matter which direction you look, no matter how far you look, everything in the cosmic microwave background looks more or less the same.
But the observable universe is so large that there isn't enough time for a photon to travel all the way to equalize temperatures everywhere. But a rapid stretching of spacetime – inflation – could have achieved this, although it would have ended when the universe was less than a trillionth of a billionth of a billionth of a second old.
Current cosmological observations agree with the picture of cosmic inflation, said Brian Keating, a physics professor at the University of California, San Diego, and one of the project's leaders.
But, Dr. Keating added, “to date there is no smoking gun.”
The accelerated expansion would have generated titanic gravitational waves that would have pushed matter in such a way as to leave B-modes imprinted in the primordial microwave radiation.
“B modes, these gravity waves seeping through the cosmos, would be equivalent to gun smoke,” Dr Keating said.
For B modes, scientists will examine a property of light known as polarization.
Light is made up of electric and magnetic fields that oscillate at right angles to each other. Usually, these fields are oriented in random directions, but when light reflects off certain surfaces, the fields can become aligned or polarized.
The polarization of light can be studied with a filter, through which only that part of the light polarized in a particular direction will pass. (This is how polarized sunglasses suppress glare. When sunlight reflects off water, it becomes polarized, similar to how light in the early universe became polarized.)
The observatory's detectors are essentially made up of rotating polarizing filters. If microwaves were not polarized, their brightness would remain constant. If they are polarized, the brightness will rise and fall: brighter when the filter aligns with the polarization, dimmer when the filter is at right angles to the polarization.
Repeating this measurement over a band of sky will reveal polarization patterns.
There are two types of polarization models. One is called the E mode, which means electric, because it is the analogue of the electric fields emanating from a charged particle. Previous microwave observations have detected E modes in primordial microwaves, generated by variations in the density of the universe.
The other polarization model has a characteristic found in magnetic fields. Since physics uses the letter B as a symbol to designate magnetic fields, it is known as B mode.
“They look like swirls,” Dr. Spergel said.
Gravitational waves would have shaken electrons to generate tiny B-modes in cosmic microwaves.
“The detection will be a Nobel Prize,” said Gregory Gabadadze, professor of physics at New York University and senior vice president for physics at the Simons Foundation. “It doesn't matter the Nobel Prize. A discovery of this magnitude, who cares what prize you give it?
Microwave measurements could also uncover other important physical phenomena, including masses of ghost particles known as neutrinos, or identify dark matter, the mysterious particles that account for 85% of the universe's mass.
Perhaps the greatest challenge for cosmologists is not to delude themselves.
That's what happened ten years ago, when scientists working on an experiment known as BICEP2, or Background Imaging of Cosmic Extragalactic Polarization, announced they had found conclusive evidence of primordial gravitational waves and cosmic inflation.
But within a year, the claim fell apart. The observed microwaves did not come from the Big Bang and inflation, but rather from dust within our galaxy, the Milky Way.
To avoid repeating this mistake, the Simons Observatory will make its observations at different wavelengths. (BICEP2 results were based on a single wavelength.)
One of the Simons Observatory's telescopes will be dedicated to detecting interstellar dust, which radiates at higher temperatures. That signal will then be subtracted, and researchers hope it will leave the cosmic microwave background.
“It's worth it for us to avoid a repeat of the fiasco that hurt us in the past,” Dr Keating said. “If this happened again, I don't think anyone would ever trust this camp.”
Following the controversy over BICEP2, Dr. Simons convinced competing research groups to work together at the Simons Observatory. “I joke that he basically forced a merger, using his experience in the hedge fund world,” Dr. Keating said.
The Simons Observatory may still not be able to find what it is looking for, or the data may be ambiguous. Perhaps spurious dust emissions will prove to be a bigger problem than expected, obscuring primordial B modes.
“It's like looking at New York City through a dirty window,” Dr. Keating said. “Nature does not have a contract with us to produce an observable signal.”
Or perhaps there are no B-modes at all. This would delight contrarian cosmologists who dislike the idea of cosmic inflation. One of the seemingly inevitable consequences of inflation is the multiverse, or the fact that the universe continually diverges into an infinity of alternative possibilities.
“Literally, every possible arrangement of matter, space, time and energy occurs somewhere in this cosmic landscape called the multiverse,” Dr. Keating said. “Some people find him very attractive, while others find him distant.”
However, all alternatives have exactly zero B-modes. Therefore, a successful detection would exclude them.
“It still wouldn't prove inflation,” said Dr. Keating, “but it would narrow the number of culprits from four or five to one.”
If the Simons Observatory detects no B-mode, this would not definitively disprove cosmic inflation. But it would make it harder to distort theoretical models to produce B-modes small enough to be undetectable.
“The inflationary paradigm will be in big trouble,” Dr. Gabadadze said. “The majority will abandon it and we will look for alternatives to inflation.”
Indeed, Dr Keating said that Dr Simons, an eminent mathematician before moving to the world of finance, was among those who would have been happy to see inflation thrown into the bin of debunked scientific hypotheses.
“This would then fit with his notion of an eternal cyclic, or bouncing, pattern for the universe,” Dr Keating said. But Dr. Simons was also willing to invest the money to find out if he could be proven wrong.
“His true love was for science,” Dr. Keating said.
