In case you missed it, on Feb 11th the team at LIGO (Laser Interferometer Gravitational-Wave Observatory) announced that they confirmed the existence of gravitational waves. This phenomenon had previously only been theorized about since Einstein proposed his theory of General Relativity in 1915, more than a century ago.
In a nut-shell, gravitational waves are vibrations in the fabric of space-time that are caused by moving masses. Similar to how electromagnetic waves (light, radio, etc.) are caused by moving charges. The team at LIGO was able to detect one of these gravitational waves, which was caused by the merging of two black holes 1.3 billion light years away.
I won’t go into more detail because there are some great videos out there about this discovery.
But I can give you a few reasons how this discovery helps us better understand the universe. . .
1. Provides the first direct evidence of black holes
Source: Computer simulation of a black hole merger.
Before the detection of gravitational waves scientists inferred the existence of black holes (as Einstein described them) due to the way objects act when they are near a black hole. These interstellar objects will accelerate as they are pulled toward the black hole and this causes them to heat up and emit x-rays.
Scientists cannot directly observe black holes because their gravity is so great that not even light can escape, but the strange behavior of nearby objects allows scientists to know where they are.
Gravitational waves have changed that.
The merging of two black holes caused the gravitational wave that LIGO detected. As the black holes swirled around one another and merged with such a large gravitational force they caused a rippling of space-time, ie. a gravitational wave. This wave was caused by the black holes.
Confirming directly, for the first time, that black holes exist.
2. Marks the beginning of gravitational wave astronomy: a whole new way to “see” the universe
Source. Visualization of gravitational waves from two black holes merging.
When you look at the stars with your naked eye, or even with a telescope, you are using the electromagnetic spectrum to study the universe. Your eyes are using the visible wavelengths of the electromagnetic spectrum to see the stars.
Scientists have studied the universe in this way for centuries. They have even expanded the portion of the electromagnetic spectrum they use beyond the visible spectrum to include other wavelengths including: x-rays, gamma rays, microwaves and radio waves.
(Fun fact: Radio waves are how astronomers look for signs of extraterrestrial life.)
The discovery of gravitational waves provides scientists with a whole new way to “see” the universe.
Gravitational waves are not a part of the electromagnetic spectrum and they are very different from electromagnetic waves because matter does not disrupt them.
Electromagnetic waves are distorted, absorbed, and reflected off of matter. This makes them less that ideal for observing phenomenon that occur many light-years away. If an electromagnetic wave from a distant cosmic event comes into contact with gases or another type of matter they will be distorted and astronomers will not get a complete picture of what’s going on.
Gravitational waves are not impeded by anything, and when scientists detect a gravitational wave they are seeing it just as it was when it was first created.
Scientists believe gravitational waves were created during the big bang. So, theoretically, gravitational waves will allow scientists to “see” the big bang all the way back to the initial singularity. Bringing with it an unprecedented understanding of our universe.
3. Holds the potential to understand dark matter and dark energy
Since gravitational waves can “see” what electromagnetic radiation cannot, scientists can use them to study what was previously invisible, like a black hole.
The key to studying dark matter and dark energy may also be gravitational waves.
If large amounts of dark matter merge or accelerate like we have seen with black holes it is possible that they would cause gravitational waves that could be detected. And if these waves were detected they would hold information about the dark matter, and would allow scientists a much greater look into what dark matter and dark energy are.
We are not there yet.
But as more and more gravitational wave detectors are developed, what was once invisible to us, may be “seen” by studying gravitational waves.
4. Demonstrates that great scientific discoveries take collaboration and persistence
A few members of the LIGO scientists.
Often in our society a few people are given credit for something that required many people to accomplish. Science is not outside of this rule. But large discoveries, like the detection of gravitational waves, require contributions from many people over many years.
Just look at the article in Physical Review Letters, which reported the observation of gravitational waves. It has more than 1000 authors. Although some may think it’s ridiculous to have so many authors on one paper, it is wonderful to see so much acknowledged collaboration.
And that collaboration began long ago. Professor Weiss had a vision for the creation of LIGO in the 1970’s, its construction was not authorized until 1990, and here we are in 2016 when the first waves were detected.
It has been more than 100 years since gravitational waves were theorized by Einstein, 40 years since a way to detect gravitational waves was devised, and more than 20 years since the detector became a physical reality.
Talk about persistence.
This lovely blog was written by: Jeanette McConnell, PhD – freelance science journalist – Australia