Has proof of Einstein's greatest prediction - gravitational waves - been found?

By Jamie Seidel

The gravitational ripples caused by two black holes colliding has reported by been detected by an international experiment in the United States. Photo / NASA
The gravitational ripples caused by two black holes colliding has reported by been detected by an international experiment in the United States. Photo / NASA

The hotly-anticipated confirmation of "ripples" wiggling through the fabric of space-time would be one of the most important discoveries of the past century, a New Zealand physicist says.

What are called gravitational waves have been a generally-accepted phenomenon since Albert Einstein predicted their existence 100 years ago in his General Theory of Relativity.

But despite decades of research, no one has yet been able to produce physical proof of these long-elusive waves, which supposedly warp the very fabric of our universe as they roll through the cosmos.

Ripples in space-time. Einstein predicted that the interaction between massive stellar objects would send out gravitational waves. Photo / Supplied
Ripples in space-time. Einstein predicted that the interaction between massive stellar objects would send out gravitational waves. Photo / Supplied

There's now growing buzz among scientists that this will be precisely what researchers from the US National Science Foundation and the Laser Interferometer Gravitational-Wave Observatory experiment (LIGO) announce tomorrow at a press conference scheduled for 4.30am NZT.

Why should we care?

Understanding how these waves work could change our very understanding of the universe -- and answer some of the intriguing questions surrounding it.

Cosmology, at least, would never be the same again.

As LIGO put it: "This will open up a new window of study on the universe, giving us a deeper understanding of these cataclysmic events, and usher in brand new cutting-edge studies in physics, astronomy, and astrophysics."

University of Auckland cosmologist Richard Easther expected that their confirmation would be as important as the discovery of dark energy, or even that of the so-called God particle, Higgs Boson.

A simulated view of two black holes on the brink of merging. Photo / Bohn et al
A simulated view of two black holes on the brink of merging. Photo / Bohn et al

"It would be one of the most important things that has been done in science in the past 100 years, it's really huge," he told the Herald.

"The idea that they might exist is something that people have long been comfortable with, but actually being able to push the technology to the point where you could pick these signals up -- that's really been the fundamental challenge that these people have grappled with and may have now solved."

The world would now have a way that can allow us to delve into the mechanics of black holes.

The concept of gravitational waves comes back to Einstein's theory that neither space nor time is fixed, and the two are instead dependent on each other: the state of one changes with the condition of the other.

For a single object sitting stationary, space and time remains static.

A similation of the shape of gravitational waves radiating out of a black hole merger. Photo / NASA
A similation of the shape of gravitational waves radiating out of a black hole merger. Photo / NASA

But if two objects collide, the matter and energy within them interacts to distort space-time -- causing the objects to accelerate and spiral towards each other.

This acceleration emits gravitational waves.

Their behaviour is thought to be similar to that of light and radio waves, except they interact with space and time itself.

"People like to talk about space as stretchy rubber space, so what you are seeing are these really violent events in space that can send out shockwaves that propagate out across the universe," Dr Easther said.


They "warp" the very fabric of the universe -- shrinking and expanding the distance between two points in the same way a flag billows in the wind.

But gravity is also the weakest force.

Gravitational waves cause such a tiny wiggle in space-time that Einstein thought they would never be detected.

Einstein inferred the energy of an exploding star -- a supernova -- would be dissipated by relatively huge gravitational waves rushing outward at the speed of light.

He also calculated that two immensely dense neutron stars orbiting each other very closely would also ripple-out immense energy as gravitational waves.


Einstein told us where to look.

It has long appeared that his idea that the huge fallout from the collision of two black holes would blast across the cosmos like a rock crashing into a still pond was the most likely to bare fruit.

So what's the problem with seeing gravitational waves produced by such a colossal collision?

On an intergalactic scale, even the incomprehensible energy of colliding black holes translates to the barest vibration of atoms inside our bodies -- or a flutter of photons between two lasers.

One of the most advanced (and expensive) efforts to catch gravitational waves in the act began in 2002: The Laser Interferometer Gravitational-Wave Observatory (LIGO). As the complicated name infers, this experiment has been attempting to measure the infinitesimal vibration of perpendicular laser beams reflected along a 4km vacuum tube in a tunnel.

Two such enormous L-shaped tunnels are positioned some 3000km apart -- one on either side of the United States.

The theory goes that any true gravitational wave would cause a ripple in the lasers at both locations.

Any nearby slamming doors would therefore be cancelled out.

For more than eight years, the sensor didn't spot anything.

Late last year, however, a major upgrade which began in 2010 was completed.

Its operators believe this laser system should be sensitive enough to detect the gravitational waves generated by two black holes (somewhere between the mass of one and several hundred Suns) crashing into each other should be detectable in a radius of 225 million light-years.

Odds are, over such an immense distance, such a collision would occur a couple of times each year.

Such an event would produce a distortion in the pattern cast by these lasers equivalent to a fraction of the width of a single proton in the nucleus of an atom.

It may have already happened.

Rumours of the discovery leaked via Twitter claim the gravitational wave detected was consistent with the clash of two black holes of 36 and 29 times the mass of the Sun. The new -- bloate -- black hole that came out of the merger appears to weigh in at 62 solar masses.

But, if true, we won't know where -- or when -- this event happened.

To gain the sort of resolution needed to pinpoint the part of the sky such a wave came from would require many more of these 4km-long laser-vacuum pits.

But plans are already afoot to increase the equipment's sensitivity much further -- enabling it to detect gravitational wave sources from more than 650 million light years away.

"There's a huge range of questions that we're going to be able to answer with this machine," Dr Easther said.

- News Corp Australia, NZ Herald

Get the news delivered straight to your inbox

Receive the day’s news, sport and entertainment in our daily email newsletter

SIGN UP NOW

© Copyright 2016, NZME. Publishing Limited

Assembled by: (static) on production bpcf03 at 04 Dec 2016 16:59:31 Processing Time: 660ms