Update – Oct. 3, 2017: Researchers Kip Thorne and Barry Barish of Caltech and Rainer Weiss of MIT have been awarded the 2017 Nobel Prize in Physics for their “decisive contributions to the LIGO detector and the observation of gravitational waves.”
Thorne, Barish and Weiss played key roles in making the LIGO project a reality through their research, leadership and development of technology to detect gravitational waves.
In a statement to Caltech, Thorne said the prize also belongs to the more than 1,000 scientists and engineers around the world who play a part on LIGO, the result of a long-term partnership between Caltech, MIT and the National Science Foundation.
This story was originally published on March 23, 2016.
In the News
A century ago, Albert Einstein theorized that when objects move through space they create waves in spacetime around them. These gravitational waves move outward, like ripples from a stone moving across the surface of a pond. Little did he know that 1.3 billion years earlier, two massive black holes collided. The collision released massive amounts of energy in a fraction of a second (about 50 times as luminous as all the stars in the visible universe combined) and sent gravitational waves in all directions. On September 14, 2015 those waves reached Earth and were detected by researchers at the Laser Interferometer Gravitational-Wave Observatory (LIGO).
Why It's Important
Einstein published the Theory of General Relativity in 1915. In it, he predicted the existence of gravitational waves, which had never been directly detected until now. In 1974, physicists discovered that two neutron stars orbiting each other were getting closer in a way that matched Einstein’s predictions. But it wasn’t until 2015, when LIGO’s instruments were upgraded and became more sensitive, that they were able to detect the presence of actual gravitational waves, confirming the last important piece of Einstein’s theory.
It's also important because gravitational waves carry information about their inception and about the fundamental properties of gravity that can’t be seen through observations of the electromagnetic spectrum. Thanks to LIGO’s discovery, a new field of science has been born: gravitational wave astronomy.
How They Did It
LIGO consists of facilities in Washington and Louisiana. Each observatory uses a laser beam that is split and sent down 2.5-mile (4-kilometer) long tubes. The laser beams precisely indicate the distance between mirrors placed at the ends of each tube. When a gravitational wave passes by, the mirrors move a tiny amount, which changes the distance between them. LIGO is so sensitive that it can detect a change smaller than 1/10,000 the width of a proton (10-19 meter). Having two observatories placed a great distance apart allows researchers to approximate the direction the waves are coming from and confirm that the signal is coming from space rather than something nearby (such as a heavy truck or an earthquake).
Creating a model that demonstrates gravitational waves traveling through spacetime is as simple as making a gelatin universe!
Middle school students can develop a model that shows gravitational waves traveling through spacetime while working toward the following Next Generation Science Standard:
- MS-PS4-2 - Develop and use a model to describe that waves are reflected, absorbed, or transmitted through various materials.
- Gravitational waves news, videos and resources
- Laser Interferometer Gravitational-Wave Observatory (LIGO) Website
A “teachable moment” turned into a science fair win for an eighth-grader in Ontario, Canada, who based his project on a classroom activity from NASA’s Jet Propulsion Laboratory.
Joshua Dove, 13, says he originally planned to explore the effects of storage temperature on golf balls until his grandfather, a space enthusiast and environmental consultant, saw a Caltech news story he had to share.
The story was about how an instrument called LIGO had detected gravitational waves for the first time, confirming a key piece of Einstein’s 1915 general theory of relativity. A web search led Dove to the JPL Education website and its “Dropping In With Gravitational Waves” activity, where he learned how to model the gravitational wave discovery using gelatin, a laser and marbles.
“Scientific models allow scientists, and students, to understand and explain phenomena that might be difficult or impossible to see,” said JPL Education Specialist Lyle Tavernier, who created the lesson for the website’s Teachable Moments blog. The blog, from the JPL Education Office, helps educators turn NASA- and JPL-related mission and science news into activities for the classroom. “While the LIGO detectors are located thousands of miles apart, this activity helps students understand gravitational waves using a model that fits on their desk!”
Dove made modifications to the JPL Education activity for his science fair project, including using Legos to create a device that could drop a marble from different heights. He says figuring out how he needed to alter the design was his favorite part of the project.
With the help of his mom and grandfather plus a few tips from Tavernier, Dove was able to modify the lesson for his science fair project, which looked at whether the model would show consistent and predictable variations in the movement of the laser (gravitational waveform) depending on the energy released during a marble (black hole) collision.
“There was a trend that suggested the greater the weight of the impacting object, the larger the amplitude of the waveform,” said Dove, noting in his abstract that there were some inconsistencies in the results that would require more testing. He plans to do that this summer.
After presenting at his school’s science fair, Dove was asked by his teacher to enter the regional competition, where he won an award from the Royal Astronomical Society of Canada.
Dove’s mom says the win was a big confidence booster for her son, who hopes to eventually work at NASA or become an inventor. “I would like to invent things that would help people affected by a natural disaster,” he said.
As far as advice for other science fair participants, Dove says, “Don't be upset if you don't get the results you are expecting, and don't be afraid to make modifications to your experiment.” In fact, he says it was working through the modifications that turned out to be his favorite part of the project.
His other advice: “Have a good mentor.” Or in Dove’s case, three. In addition to support from his grandfather and mom, it was Dove’s older sister, a science fair winner herself, who encouraged him to enter the regional competition. And thanks to the encouragement, Dove has no plans to stop now. “I would like to learn more about detecting other intergalactic phenomenon,” he said.
For tips on creating a winning science fair project, watch JPL Education’s “How to Do a Science Fair Project” video series.
Explore the gravitational waves activity and more standards-aligned STEM lessons for grades K-12 at: http://www.jpl.nasa.gov/edu/teach
The laboratory’s K-12 education initiatives are managed by the JPL Education Office. Extending the reach of NASA’s Office of Education, JPL Education seeks to create the next generation of scientists, engineers, technologists and space explorers by supporting educators and bringing the excitement of NASA missions and science to learners of all ages.