UF physicists join global collaboration to track gravitational waves in space
TAMPA - Physicists at the University of Florida helped make striking new discoveries in space. Now they're part of a global collaboration to build a giant space antenna that could greatly expand our knowledge of the universe and how it came to be.
For background, Albert Einstein proved space and time warp around matter, and this curvature of spacetime is what we feel with the pull of gravity. Einstein also predicted big objects and collisions that produce ripples in spacetime called gravitational waves. So, more than 30 years ago, the University of Florida partnered with Cal Tech and MIT to build a gravitational wave detector called LIGO to prove Einstein was right.
OTHER BREAKTHROUGH IN SCIENCE STORIES
"UF has played a really large role, right from the beginning," said UF Physicist Dr. Paul Fulda. "UF provided a significant amount of the optics and design of the (LIGO) interferometer."
An interferometer is a triangular device that fires and splits laser beams--making it an incredibly precise ruler. When a gravitational wave rolls through the triangle, the laser ruler can detect the stretching of space.
In building LIGO, they constructed a long interferometer in Hanford, Washington, and another in Livingston, Louisiana. In 2015, LIGO detected its first gravitational wave. It carried enough information to reveal that the wave came from two black holes crashing together 1.3 billion years ago (it took that long for the wave to reach Earth in 2015).
"It is a stretching and squeezing of spacetime. The fabric of the universe," explained Dr. Fulda.
The stretching and squeezing of spacetime was within a thousandth of the length of an atomic proton, and LIGO detected and measured it with an algorithm developed by & UF Professor Sergey Klimenko.
"It’s very rewarding. And I think the most important part is seeing something new," said Dr. Klimenko.
After the initial discovery in 2015, LIGO detected more black hole collisions, and in 2017 it detected waves from two neutron stars spiraling and then fusing together 140-million light-years away. This was an astronomical gold mine, as scientists confirmed neutron star spirals cook up the gold throughout the cosmos. And as a Nobel Prize and more gravitational waves rolled in, it drove the plan to build a much larger detector to reveal so much more.
That brings us University of Florida's current project. UF is working with NASA, the European Space Agency, and other partners to develop LISA— the Laser Interferometer Space Antenna. When complete and fully operational, it will stretch millions of miles into space.
On one side of UF's LISA Lab, researchers fire green lasers into iodine to make precise measurements of jiggling molecules. On the other side, you'll find optical benches with lenses and mirrors. They fire and bounce lasers we can't see until they reveal them with special paper because they're near infrared.
Their sensors are incredibly sensitive to any vibrations. It even picks up foot traffic as classes change across campus. They're currently improving the sensitivity of the detectors and testing LISA's components.
"Our biggest project is testing the dimensional stability of the telescope," said Dr. Fulda.
The telescope is buried in thermal shielding to replicate space as they test how well lasers pass through it.
After it’s launched, three spacecraft millions of miles apart will form a gigantic triangle. They’ll bounce lasers like LIGO, but LISA will detect waves with much longer frequencies. That means it will detect much heavier things like supermassive black holes crashing together. LISA will detect waves formed near the beginning of time and space and provide a clearer picture of how it came to be.
"We know surprisingly little about the universe, and it’s very hard to probe the very early time and how things began," said Dr. Imre Bartos.
And LISA’s mission is especially important now that the James Webb Space Telescope is revealing galaxies that challenge our concept of their creation.
"Now we can see the beginning of the universe, and not everything agrees," said Dr. Klimenko.
Neither do our basic laws of science. The laws that govern the small world of particles clash with the laws that govern heavy objects in the world we recognize.
There appears to be a missing link that could unify those laws and physicists are trying to find it.
"The key question is can we have something that is actually observable and measurable," said Dr. Bartos.
That's how observing and measuring waves from supermassive black holes could pay off, because that's where the worlds of the very heavy and the very small combine. Dr. Bartos said LISA could help transform our understanding of nature.
"And one of key discoveries we could make is to find something that is different from the fundamental laws of physics as we currently understand them," he said.
They plan to complete and launch LISA in the 2030s.
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