It isn't obvious and it took us a while to demonstrate that we could actually design a machine that bends.
The technical challenges were technical challenges that were not unbeatable; it was just that we had to learn how to do things and how to build a sensitive enough device. That took us 20 years after we built the first version of the LIGO detector.
The 4th Concept is welcomed and encouraged. In the end, it's my hope and belief that the best ideas are what will be used in these detectors.
Everything we know about the universe is studied by using telescopes or other instruments that look at visible light, infrared, ultraviolet or X-ray - different wavelengths of electromagnetic interactions. Only 4 percent of what's in the universe gives off electromagnetic radiation, so we don't have any handle on the rest.
Einstein had two new predictions from general relativity. One was that light would bend. That was tested in 1919, and basically, he was proven right. The second prediction was gravitational waves, which took us 100 years to prove. The theory itself, which is thought by most to be rather obscure, you use every day, probably.
Scientists, especially physicists, we're presumptuous and think we can do everything better than everybody else. And one thing that I realized early is, I had some talent managing and organizing things - you know, some people are better organizers than others - but why should I reinvent the wheel?
A lot of missions for NASA or experiments on accelerators happen through a whole process of scientific retreats, long-range planning, forming collaborations to do studies - all this kind of stuff. It's very democratic.
When the signal reached LIGO from a collision of two stellar black holes that occurred 1.3 billion years ago, the 1,000-scientist-strong LIGO Scientific Collaboration was able to both identify the candidate event within minutes and perform the detailed analysis that convincingly demonstrated that gravitational waves exist.
I have somewhat ambivalent feelings about the recognition of individuals when so much of this was a team effort.
The waves are subtle, altering spacetime and the distance between objects as far apart as the Earth and the Moon by much less than the width of an atom. As such, gravitational radiation has not been directly detected yet. We hope to change that soon.
