Einstein’s Gravitational Waves Confirmed
Interstellar discovery across more than 1 billion light years heralds a new understanding of the universe.
Turns out, Einstein was right. Two black holes colliding converts a portion of their mass into energy, resulting in gravitational waves, strange disturbances in the very fabric of spacetime.
An international collaboration of researchers affiliated with the Laser Interferometer Gravitational-Wave Observatory, or LIGO, announced Thursday “the first direct detection of gravitational waves and the first observation of a binary black hole merger” according to the paper, published today in the Physical Review of Letters. The now-proven existence of such waves, and especially the technology that went into finding them, could have relevance for future communications, perhaps enabling future long-distance communications technologies that don’t use the electromagnetic spectrum in the way that we do today. Or it could inform the development of future location positioning techniques that don’t rely on GPS. Both of those would have relevance for a military that is increasingly worried about the security of the global positioning system and an increasingly crowded electromagnetic spectrum. More importantly, the discovery could change as well as humanity’s understanding of space and time.
The observance occurred Sept. 14 at 5:51 AM. What specifically they detected was the faint remnants of two black holes merging some 1.3 billion years ago. Each black hole was about 150 kilometers in diameter but some 30 times the mass of the sun. They were accelerating to half the speed of light when they collided.
It’s an incredible feat of detective work considering that, by the time those waves reached Earth, each one is one thousandth the diameter of a proton.
How does LIGO work? You take a laser and aim it a beam splitter, then you aim the two split beams at two mirrors that are about 4 kilometers apart. The mirrors are hanging above the ground, “quadruple suspended,” which isolates them from unwanted vibrations. Then you pass the beams that they reflect through a mass test and then a photodetector. If, after calculating the possible interference from all the noise (which is the real hard part) you observe a distorted waveform, that could be your gravitational wave. That’s what the researchers detected for about 20 milliseconds.
They repeated the observance at two sites, one in Livingston Louisiana and, 70 seconds later, at a second detector in Hanford, Washington. The wave distortion that they observed at both sites corresponded to Einstein’s equations, and a lot of supercomputer modeling, for gravitational waves.
“We had only seen warped space time when it is very calm“ said Kip Thorne of Caltech, one of the authors of the paper, at a National Press Club briefing on Thursday. The breakthrough opened a window into “a violent storm in the fabric of space and time.”
It also shows the precision of modern instruments for detecting minute disturbances in the universe, which could go on to change what is known about the electromagnetic spectrum. The researchers imagine that there could be technological spinoffs in terms of lasers.
It could also yield new—through indirect—breakthroughs in electronic communications. After all, Einstein’s theories on relativity are part of the reason we can use smart phones and cell signals for localization. No, it doesn’t mean we will be able to use gravity waves to make phone calls. It may be theoretically possible to use a new understanding of gravity waves to change the way we communicate using the electromagnetic spectrum. Electromagnetic waves are produced from oscillation in the electromagnetic fields. Gravity waves are produced from changes in the fabric of space time. But you still need to reduce noise in the electromagnetic spectrum to see it. At very least, the breakthrough holds promise for new ways of observing the physical echo of events on earth at great distance.
“These gravitational waves are very hard to detect … They don’t interact very much with anything else. We had to build this fancy apparatus to be able to see these things. So that says something very important,” said Reiner Weiss of MIT.
But the real value: “An understanding of the fundamental laws that control the universe,” according to Thorne, which he called “Much bigger than any kind of technological spinoff.”