Physicists Are Freaking Out About
Gravitational Waves and You Should Too
February 27, 2016
Story at-a-glance
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In September 2015, nearly 100 years after Einstein’s
prediction, the first gravitational waves were
observed
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Gravitational waves are “ripples in the fabric of
space-time caused by some of the most violent and
energetic processes in the Universe”
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The source of the waves was a collision between two
black holes that took place 1.3 billion light years
ago
By Dr. Mercola
In 1916, Albert Einstein predicted the existence of
gravitational waves in his general theory of relativity.
Gravitational waves are "ripples in the fabric of space-time
caused by some of the most violent and energetic processes in
the Universe," according to the Laser Interferometer
Gravitational-Wave Observatory (LIGO).1
LIGO is the world's largest gravitational wave observatory,
with detectors in Livingston, Louisiana and Hanford, Washington.
In September 2015, nearly 100 years after Einstein's prediction,
the discovery of a lifetime was made: both of LIGO's detectors
observed gravitational waves, a historical first.
The source of the waves was a collision between two black
holes that took place 1.3 billion years ago. The "violent
astrophysical event" was virtually beyond comprehension in
scale, as each black hole is said to have had a mass that was
more than 25 times greater than that of the sun.2
The discovery was kept largely quiet for five months, while
physicists worked tirelessly to confirm their astounding
finding. In February 2016, the announcement was made public and
published in the journal Physical Review Letters:3
"A century after the fundamental predictions of
Einstein and Schwarzschild [who published work that further
the discovery of black holes], we report the first direct
detection of gravitational waves and the first direct
observation of a binary black hole system merging to form a
single black hole."
Advanced LIGO Gets the Job Done
The first-generation LIGO experiment operated for nearly a
decade with no results. Detecting gravitational waves is no easy
feat, and the original technology just wasn't sensitive enough.
As reported by Gizmodo:4
"Gravitational waves are minuscule — the atomic
jitters that pass through our world when two black holes
bash together in a distant galaxy are on the order of a
billionth of a billionth the diameter of an atom.
LIGO detects them by proxy, using high powered lasers
to measure tiny changes in the distance between two objects
positioned thousands of miles apart.
A million things can screw this up, including a
rumbling freight train, a tremor in the Earth, and the
inconvenient reality that all objects with a temperature
above absolute zero are vibrating all the time."
Upgrades over the last five years led to an advanced LIGO
system that began operating in September 2015, just days before
the first waves were detected.
It has new-and-improved lasers and is better able to separate
potential gravitational waves from background "noise." It also
allows a larger volume of the universe to be probed.
When the first waves were detected, researchers could hardly
believe their luck and quickly set to work confirming that the
signal was real (and it was!). Gizmodo continued:5
"According to Einstein's theory of relativity, when a
pair of black holes orbit on another, they lose energy
slowly, causing them to creep gradually closer.
In the final minutes of their merger, they speed up
considerably, until finally, moving at about half the speed
of light, they bash together, forming a larger black hole. A
tremendous burst of energy is released, propagating through
space as gravitational waves.
The two black holes behind the all the hubbub are 29
and 36 times the mass of the Sun, respectively. During the
peak of their cosmic collision, LIGO researchers estimate
that their power output was 50 times that of the entire
visible universe.
'The description of this observation is beautifully
described in the Einstein theory of general relativity
formulated 100 years ago and comprises the first test of the
theory in strong gravitation,' said Rainer Weiss, who first
proposed LIGO as a means of detecting gravitational waves in
the 1980s.
'It would have been wonderful to watch Einstein's
face had we been able to tell him.'"
Why Detect Gravitational Waves?
The physics world is abuzz with this new discovery. Scott
Hughes, Ph.D., an astrophysicist at MIT, told Gizmodo:6
"Seeing the data that the public just saw hit me like
at ton of bricks … Imagine twenty three years of your career
suddenly coming to fruition. It's hard to express the way
everything seemed to just fall into place."
The finding is expected to set the course for a "new era of
observational astrophysics," so it's easy to understand why
physicists are excited.7
But there's reason for everyone to share in on this excitement.
The detection of gravitational waves is only the beginning.
Electromagnetic radiation has historically been the only tool
to observe and understand the goings-on of the universe.
Gravitational waves offer an entirely new method for
observation, as they carry "information about cosmic objects and
events that is not carried by electromagnetic radiation," LIGO
noted.8
Writing in the journal Physics, Emanuele Berti, Ph.D. of the
Department of Physics and Astronomy at the University of
Mississippi, explained it this way:9
"With Advanced LIGO's result, we are entering the
dawn of the age of gravitational wave astronomy: with this
new tool, it is as though we are able to hear, when before
we could only see.
It is very significant that the first 'sound' picked
up by Advanced LIGO came from the merger of two black holes.
These are objects we can't see with electromagnetic
radiation. The implications of gravitational-wave astronomy
for astrophysics in the near future are dazzling."
Part of what makes gravitational waves such a perfect
"window" into the universe is the fact that they don't interact
with matter, so they travel through the universe unimpeded. LIGO
explained:10
"They will carry information about their origins that
is free of the distortion or alteration suffered by
electromagnetic radiation as it travels through millions of
light years of intergalactic space. With this completely new
way of examining astrophysical objects and phenomena,
gravitational waves will truly open a new window on the
Universe …
… [P]roviding astronomers and other scientists with
their first glimpses of previously unseen and unseeable
wonders, and greatly adding to our understanding of the
nature of space and time itself."
Third LIGO Interferometer to Be Built in India
Following the momentous announcement, the Indian Cabinet
approved funding to build a third LIGO detector in India. The
addition of a third detector is expected to help scientists
better pinpoint gravitational waves. It may be activated by the
end of 2023.
While researchers are anticipating several sources and types
of gravitational waves to appear, they're also anticipating new
discoveries that have yet to be anticipated. LIGO Laboratory
Executive Director David Reitze, Ph.D. said in a press release:11
"Any time you turn on some new type of telescope or
microscope, you discover things you couldn't anticipate. So
while there will be certain sources of gravitational waves
that we expect to see, the really exciting part is what we
did not predict and what we did not expect to see."
In case you were wondering how gravitational waves
are detected by LIGO, it involves the use of laser
interferometers. As the press release explained it:12
"At each observatory, the two-and-a-half-mile (4-km)
long L-shaped interferometer uses laser light split into two
beams that travel back and forth down the arms (four-foot
diameter tubes kept under a near-perfect vacuum). The beams
are used to monitor the distance between mirrors precisely
positioned at the ends of the arms.
According to Einstein's theory, the distance between
the mirrors will change by an infinitesimal amount when a
gravitational wave passes by the detector. A change in the
lengths of the arms smaller than one-ten-thousandth the
diameter of a proton (10-19 meter) can be detected.
According to David Reitze, executive director of LIGO
and a Caltech research professor, the degree of precision
achieved by Advanced LIGO is analogous to being able to
measure the distance between our solar system and the sun's
nearest neighbor Alpha Centauri — about 4.4 light-years away
— accurately to within a few microns, a tiny fraction of the
diameter of a human hair."
Discoveries About the Nature of Gravity Could Be Around the
Corner
The gravitational waves from black holes are expected to shed
new light on the universe as we know it, including, perhaps,
telling us about the nature of gravity itself. "Does gravity
really behave as predicted by Einstein in the vicinity of black
holes, where the fields are very strong? Can dark energy and the
acceleration of the Universe be explained if we modify
Einstein's gravity? We are only just beginning to answer these
questions," Berti pondered.13
One thing’s for certain – if you’re a physics buff, things
are really going to get interesting in the next few decades. You
can also check out my own foray into zero gravity in the video
at the top of this article.
© Copyright 1997-2016 Dr. Joseph Mercola. All Rights Reserved.
http://articles.mercola.com/sites/articles/archive/2016/02/27/gravitational-waves.aspx
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