In 1915 Albert Einstein’s General Theory of Relativity predicted there would be measurable gravity waves. One hundred years later they have been detected. This opens the door to new ways of studying gravity and the universe.

Quoiting news releases:

The gravitational waves were detected on Sept. 14, 2015 at 5:51 a.m. Eastern Daylight Time (9:51 UTC) by both of the twin Laser Interferometer Gravitational-wave Observatory (LIGO) detectors, located in Livingston, Louisiana, and Hanford, Washington, USA.

My first question is what’s a LIGO? (lī•gō)We know what a laser is, a device that produces collimated, monochromatic, and synchronized light, synchronized with itself. The meaning is each light wave is in step with all its sister waves, all waves are the same length, and all are going in the same direction, parallel. (Reference) 

An Interferometer is a device that measures interference. If you think of water in a pond and toss a rock in you see waves/ripples travel across the surface. These are just like light waves. Imagine tossing two rocks far apart into the pond. The image sort of shows the pattern we would see in a pond, but it is a laser pattern. But, it shows the two sets of rings interfering with each other.

Where the crests of two waves comes together we get a double high wave (brighter) and for troughs a double deep trough (dark). Where a crest and trough meet they cancel each other out (neutral or ambient level light). The pattern of high and low spots is the interference pattern. As you can see, laser light can form interference patterns when the out of sync waves come together.

LIGObservatories use lasers projecting over thousands of meters to detect gravity waves that interfere with the light by stretching it in one direction and compressing it in another. It takes long distances to measure the really tiny differences. Even then until last September the detectors were so primitive natural heat and other noise in the detectors hid the gravity wave distortions.

LIGO was originally proposed as a means of detecting these gravitational waves in the 1980s by Rainer Weiss, professor of physics, emeritus, from MIT; Kip Thorne, Caltech’s Richard P. Feynman Professor of Theoretical Physics, emeritus; and Ronald Drever, professor of physics, emeritus, also from Caltech

As one of the researchers says, this detector is similar to Galileo’s first telescope.

A gravity wave travels through the fabric of 3-dimensional space. But, at what speed? Einstein predicts it will be near the speed of light. But, we don’t know, yet.

Is gravity like light, particle and wave? Probably not, but may be. In theoretical physics they use a particle known as a graviton to make the math we use now work out. Light as a particle cannot escape a block hole. Gravity waves are traveling from black holes across the universe. So, is the black  hole affecting the fabric outside the hole to generate the wave? Or does the wave actually escape the hole? TBD.

The Q&A is here: Your Questions About Gravitational Waves, Answered.