The universe came into being 13.8 billion years ago, and what happened in those first moments 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 a really profound question,” said David Spergel, president of the Simons Foundation, a nonprofit that supports cutting-edge research in mathematics and science. “And what's really exciting to me is the fact that we now have observations that can give us insight into this.”
A new $110 million observatory in the high desert of northern Chile, funded by $90 million from the foundation, could discover vital clues about what happened after the Big Bang by observing particles of light that have been traveling through space since almost ancient times.
The data may finally provide compelling support for a fantastical idea called cosmic inflation, which suggests that during the first tiny moment of the universe's existence, the fabric of space-time accelerated to speeds far greater than the speed of light.
Alternatively, the observatory's measurements could overturn this hypothesis, which is a pillar of our current understanding of cosmology.
The observatory is named after the foundation and its founders, hedge fund billionaire and philanthropist Jim Simons and his wife, Marilyn, an economist, who died on May 10. Two of the four telescopes began taking measurements in April, in time for what would have been Simons' 86th birthday on April 25.
“That was kind of the goal that Jim set a long time ago for the completion of the project,” Dr. Spargel said, “and we achieved it.”
Set amid a majestic, desolate landscape at 17,000 feet above sea level, the observation deck is home to three small telescopes resembling ice cream cones and a larger one made of a pointable box shaped like a relative of a “Star Wars” droid.
The telescopes collect microwaves, which have wavelengths longer than visible light but shorter than radio waves. Two of the small telescopes are already collecting data; a third will join in the coming months, and a fourth, larger one will begin operating next year.
Some 60,000 detectors across four telescopes will study the microwave glow that fills the universe.
“This is a unique instrument,” said Suzanne Staggs, a professor of physics at Princeton University and co-director of the Simmons Observatory. “We have so many detectors.”
For the first 380,000 years of the universe's existence, temperatures were too high for hydrogen atoms to form, so photons (particles of light) bounced off charged particles, being absorbed and emitted repeatedly. But as soon as hydrogen formed, photons could travel unimpeded. They cooled to just a few degrees above absolute zero, and their wavelengths extended into the microwave region of the spectrum.
The cosmic microwave background was first observed half a century ago, when an antenna in Holmdel, New Jersey, accidentally picked up a hissing noise.
In the 1990s, NASA's Cosmic Background Probe revealed tiny temperature ripples in cosmic microwaves — a fingerprint of what the early universe was like. These fluctuations reflect changes in the universe's density, and denser regions later merged into galaxies and formed larger-scale superclusters, arranged like a cosmic spider's web.
Simons Observatory aims to reveal even more details about microwaves, including swirling patterns of polarized light that cosmologists call B-modes.
MIT professor Alan Guth proposed the idea of cosmic inflation 45 years ago to explain the monotonous homogeneity of the universe: No matter which direction you look, no matter how far you look, all of the cosmic microwave background radiation looks more or less the same.
But the observable universe is so vast that there wouldn't be enough time for a photon to travel throughout it and equalize the temperature everywhere, but a rapid stretching of space-time, or inflation, could have achieved that – though it would end less than a trillionth of a trillionth of a second after the universe began.
Brian Keating, a professor of physics at the University of California, San Diego and one of the project leaders, said current cosmological observations are consistent with a picture of cosmic inflation.
But Dr Keating added: “At the moment there is no conclusive evidence.”
The accelerated expansion is thought to have generated giant gravitational waves that shook matter and imprinted B-modes in the primordial microwave radiation.
“B-modes, which are gravitational waves that spread throughout the universe, are the equivalent of gun smoke,” Dr Keating said.
For B-mode, scientists will look at a property of light called polarization.
Light is made up of electric and magnetic fields oscillating at right angles to each other. Normally, these fields are randomly oriented, but when light reflects off certain surfaces, the fields can become aligned, or polarized.
The polarization of light can be studied by using filters that allow only parts of light polarized in certain directions to pass through. (This is how polarized sunglasses reduce glare. When sunlight reflects off water, it becomes polarized, in the same way that light was polarized in the early universe.)
The observatory's detectors essentially consist of rotating polarizing filters. If the microwaves are unpolarized, their brightness stays constant. If they are polarized, their brightness goes up and down. They're brightest when the filter is aligned with the polarizing light, and dimmer when the filter is at right angles to the polarizing light.
Repeating this measurement over a wide area of the sky reveals patterns in polarization.
There are two types of polarization patterns. The first is called E mode (electrical) and is an analogue of the electric field emanating from charged particles. Previous microwave observations have detected E mode in primordial microwaves generated by density changes in the universe.
The other polarization pattern has characteristics seen in a magnetic field and is known as B-mode, because in physics the letter B is used as the symbol for a magnetic field.
“It looks like a spiral,” Dr. Spargel said.
It is thought that gravitational waves shake electrons, generating tiny B-mode waves in the cosmic microwaves.
“The discovery is Nobel-worthy,” said Grigory Gavadadze, a physics professor at New York University and senior vice president for physics at the Simons Foundation. “Never mind the Nobel Prize. Who cares what prize you give for such a momentous discovery?”
Microwave measurements may also reveal other key physical phenomena, such as the mass of ghostly particles called neutrinos, and may even pinpoint dark matter, the mysterious particle that makes up 85 percent of the mass of the universe.
Perhaps the greatest challenge for cosmologists is not to fool themselves.
That's exactly what happened ten years ago: scientists working on an experiment known as BICEP2 (Cosmic Extragalactic Polarization Background Imaging) announced that they had found conclusive evidence of primordial gravitational waves and cosmic inflation.
Within a year, however, that claim was blown away: the microwaves observed did not come from the Big Bang or inflation, but from dust in the Milky Way galaxy.
To avoid repeating that mistake, Simons Observatory will be making observations at multiple wavelengths (BICEP2 findings relied on only one wavelength).
One of Simons Observatory's telescopes will be used to detect hot, radiating interstellar dust, whose signal can then be subtracted, leaving only the cosmic microwave background radiation, researchers hope.
“It's worth our vigilance to make sure the debacles that have plagued us before aren't repeated,” Dr Keating said. “If that happens again, nobody will have any confidence in the field.”
In the aftermath of the BICEP2 controversy, Dr Simons persuaded competing research groups to collaborate at the Simons Observatory. “I joke that he used his experience in the hedge fund world to basically force the merger,” Dr Keating said.
Simons Observatory may still not find what it's looking for, or the data may be fuzzy — perhaps erroneous emission from dust will be a bigger problem than expected, obscuring the pristine B-modes.
“It's like looking at New York City through a dirty window,” Dr. Keating says. “Nature hasn't made a contract with us to produce an observable signal.”
Or maybe there is no B-mode at all, which would delight contrarian cosmologists who dislike the idea of cosmic inflation, one of the inevitable consequences of which is a multiverse, in which the universe constantly branches out into an infinite number of alternative possibilities.
“Literally every configuration of matter, space, time and energy occurs somewhere in this cosmic landscape called the multiverse,” Dr Keating said. “Some people find that very fascinating, others find it disturbing.”
However, all alternatives predict B-mode to be exactly zero, and therefore, successful detection will rule them out.
“It still doesn't prove inflation, but it might help us narrow down the causes from four or five to one,” Dr Keating said.
If Simons did not detect a B-mode, it would not completely rule out cosmic inflation, but it would be harder to distort theoretical models to produce a B-mode that is too small to be detected.
“The inflationary paradigm will face big challenges,” Dr. Gavadadze said. “The majority will abandon it and we will look for alternatives to inflation.”
Indeed, Dr Symons, a distinguished mathematician before moving into finance, was one of those who would have been happy to see inflation consigned to the bin as a disproval of a scientific hypothesis, Dr Keating said.
“That would be consistent with his idea of an eternal cycle or bouncing model of the universe,” Dr Keating said, but Dr Symons was also willing to put money into finding out whether he could prove him wrong.
“His true love was science,” Dr Keating said.