In the Austrian success story of gravitational waves, detecting something tiny can be a huge leap forward
On February 11, 2016, the last of Albert Einstein’s scientific predictions was officially confirmed. Now, a hundred years after the physicist had predicted their existence in his theory of general relativity, researchers found evidence of “gravitational waves” – waves caused by massive cosmic cataclysms that were, quite literally, disturbing the universe (see box on next page).
It had been a massive undertaking by the LIGO Scientific Collaboration – a project connecting some 1,000 scientists and 44,000 Einstein@Home users, who jointly analyzed data provided by two U.S. observatories – that is now a likely contender for the next Nobel Prize in Physics.
Work on the next generation of detectors is already at hand and a tiny Viennese start-up, Crystalline Mirror Solutions GmbH (CMS), is likely to provide the optical technology that is a key element for the observatories.
So how did a three-year old company with ten employees get involved with a Big Science project connecting researchers from more than 90 universities and institutes in fifteen countries?
The ball got rolling when, in 2007, Dr. Garrett Cole from the Lawrence Livermore National Laboratory reached out to Dr. Markus Aspelmeyer, an expert on quantum optics at the University of Vienna. At that time, Aspelmeyer was trying to figure out how to build micro-resonators for experiments in quantum physics. Cole, an expert with a very different background in materials science and semiconductors, turned out to be just the right person to help.
In 2008, he was invited to Vienna through an EU-sponsored Marie Curie International Fellowship.
The two created mirrors with better optical and mechanical properties. Documenting their results and looking at the wider picture, they realized that other scientific sectors might well benefit from a byproduct of their discoveries. When used as a mirror coating, their novel materials would reduce “thermal noise”. In particular, Aspelmeyer told METROPOLE, LIGO had published a stream of papers after 2000 complaining that “thermal noise was a fundamental obstacle to further progress in detection.”
Turning down the optical noise
LIGO is a Laser Interferometer Gravitational-wave Observatory that consists of two detectors operating in unison standing some 3,000 kilometers apart. Its purpose is to measure the minute ripples in space-time caused by passing gravitational waves (see graphic on next page).
Such a wave would distort a four-kilometer laser beam by less than a thousandth of the diameter of the nucleus of an atom. So, LIGO required the world’s best and largest precision optical instruments. It should have been a perfect fit.
But things are never that simple. “We were told it would never work,” recalled Aspelmeyer of their first approach in 2008. Undaunted, Cole and Aspelmeyer toiled away at developing a product that would. In 2009, they recruited a world-leader in innovative precision systems, the EV Group, a family-owned firm based in Upper Austria.
From the lab to the limelight
There were meetings in a Cambridge, Massachusetts bar with LIGO optics experts, and in Australia with the world’s foremost atomic-clocks specialist, Jun Ye, from the Joint Institute for Laboratory Astrophysics (JILA). The latter was struck by the potential of the technology and immediately agreed to measure the mirrors’ noise performance. A promising partnership was born.
Back in Vienna, the university encouraged the two to set up a company, attend business workshops and apply for start-up money, even helping them to establish the relevant contacts. In 2012, they set up a spin-off of the University of Vienna and the Vienna Center for Quantum Science and Technology (VCQ): Crystalline Mirror Solutions OG (Offene Gesellschaft, a partnership). The VCQ had just been established by the Austrian Academy of Sciences, University of Vienna and Vienna University of Technology to bring together the city’s 200 leading quantum physicists.
Colleagues “outside Austria tell me that they envy CMS for all the support we got,” Aspelmeyer said gratefully. Sound advice and financial assistance were provided by the Vienna Business Agency and the Austria Wirtschaftsservice (the Austrian Federal Development Bank). The European Research Council also helped with a grant. All of these made development of the prototype with JILA possible, leading to a seminal joint publication in 2013.
The LIGO consortium had spent ten years trying to reduce their mirrors’ thermal noise, achieving a meager 20% improvement whereas CMS attained a 300% leap. “Our results speak for themselves,” rejoiced CMS chairman Aspelmeyer. The response from the scientific community was tremendous, and demand for low-noise reflective optics was high. But within an academic environment, manufacturing was not feasible, so the one-year old CMS transitioned to a GmbH (LLC) in August 2013 and founded an American subsidiary.
“Under the proper conditions, fundamental research will yield entirely unexpected technological innovations,” Cole has written. “In that vein, CMS now stands out as another example of how the exploration of fundamental questions can generate an unexpected high-tech product,” given the excellent research support infrastructure in both Austria and the EU.
But there is a caveat, warned Aspelmeyer: Industrial and applied research get good funding here; not so basic research, which gets about twenty times less. “This is a joke!” he said forcefully, worrying that such underfunding could cripple scientific innovation within a decade.
Today CMS produces high-performance mirrors with a new, crystalline coating technique for laser-based measurement and manufacturing systems. To build the world’s most stable clock, CMS has teamed up with partners at two leading national laboratories for metrology (the science of measurement): the Physikalisch-Technische Bundesanstalt in Germany and the U.S. National Institute of Standards.
CMS applications in other fields also have strong commercial potential. Cole is convinced that “improving the sensitivity of optical precision measurement systems has a far-reaching impact, from fundamental scientific research efforts to advanced technologies, including trace chemical analysis, inertial navigation, and broadband communications.”
To infinity and beyond
CMS has joined forces with the LIGO Scientific Collaboration’s smaller gravitational wave detector, GEO600, near Hannover. There, CMS prototype mirrors are running the gauntlet of testing and quality control. If all goes well, in three to five years the next generation of large detectors in the U.S. may incorporate cutting-edge optics (30+cm diameter) pioneered by CMS. The interferometers’ increased sensitivity should enable us to catch signals from even more remote cosmological events. Hopes are high that more breakthroughs in gravitational astronomy will follow.
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The hard science behind this milestone is hard to fathom for ordinary mortals. You start with an ultra-sensitive detector, whose precision is equivalent to measuring the distance to the nearest star to an accuracy smaller than the width of a human hair. Add in two black holes, both many times the mass of our sun, spinning at half the speed of light until they collide and merge. After the distant crash of these two black holes about 1.3 billion years ago you end up, according to Einstein’s mathematics, with a “gravitational wave” in the cosmos; this is what the interferometers designed by the LIGO consortium detected on Earth last September.
“This was the last cornerstone for the verification of Einstein’s theory,” confirmed Prof. Peter C. Aichelburg, professor of Gravitational Physics at the University of Vienna.
Gravitational waves, write the scientists at LIGO, are “ripples in the fabric of space-time, caused by some of the most violent and energetic processes in the Universe.” Einstein showed mathematically that the collision of massive accelerating objects – neutron stars or black holes – would set off “waves of distorted space” radiating from the source like the ripples from a stone thrown into a pond. Traveling at the speed of light, these ripples carry information about the cataclysms that set them off, and invaluable clues to the nature of gravity itself.
These waves are a beguiling new medium to observe the universe. For a long time, we used light waves; then came radio waves, microwaves, x-rays and gamma rays, which hugely boosted the science of astronomy. Now gravitational waves will enable astronomers to detect objects and structures in the universe that can’t be observed by the electromagnetic spectrum.
Besides, electromagnetic waves can “only” take us back to 400,000 years after the Big Bang, because the infant universe was so opaque that even light could not break free. But “gravitational waves can penetrate the early stages of the universe,” Aichelburg explained. This will enable astronomers to explore most of the “dark” cosmos for the first time, and travel way back in time. A new era of scientific discovery has just begun under our eyes.