Einstein’s ‘Gravitational Waves

One hundred years ago Albert Einstein, in his General Theory of Relativity, predicted the existence of a Dark Side of the Force to the cosmos.

He postulated the presence of invisible “gravitational waves” – ripples in space-time produced by some of the most violent events in our vast cosmic timeline; exploding stars, black hole collisions, and even the primordial violence of the Big Bang itself.

For decades, astronomers have accumulated evidence to support the existence of these gravitational waves. But they had never been directly detected – until now. These waves were the last element of Einstein’s General Theory that still needed to be verified; and now they apparently have been.

The discovery dates back to last September, when two giant measuring devices in different parts of America (one in Livingston, Louisiana, and the other in Hanford, Washington), called LIGO (Laser Interferometer Gravitational-Wave Observatory), are said to have detected a passing gravitational wave – ripples in the fabric of space-time – from the collision of two massive black holes.

This first ever direct detection of gravitational waves was announced yesterday. We are told that the two black holes that collided were respectively about 29 times and 36 times the mass of our sun. It is also cited as the first direct evidence that black holes even exist, that they can exist in a pair, and that they can collide and merge.

The collision occurred a long time ago (in a galaxy far, far away); more than one billion light years from Earth. The event is said to have converted three times the mass of our sun into ‘gravitational wave energy’. In just a fraction of a second, the unfathomable power radiated through those waves is said to have been more than ten times greater than the combined luminosity of every star and galaxy in the observable universe. This event was so massive that it is said to have significantly warped the fabric of space-time, creating ripples that spread out across the universe – only having been detected by science just months ago.

Listen to what colliding black holes sound like: http://www.space.com/31910-what-colliding-black-holes-sound-like-video.html

The excitement generated over this announcement has predictably been met by apathy or scepticism in some quarters – mostly by the same people that are generally suspicious of science anyway or whose reaction to any scientific breakthrough or announcement tends to be along the lines of ‘well, why don’t they stop exploring all these useless things and just focus on curing diseases and ending world hunger?’

The discovery isn’t only about confirming Einstein’s theory, however. As Gren Ireson, Professor of Science Education, Research Coordinator within the School of Education at Nottingham Trent University, writes; ‘Now that we know that they exist, the hope is that gravitational waves could open up the door to answering some of the biggest mysteries in science, such as what the majority of the universe is made of. Only 5% of the universe is ordinary matter with 27% being dark matter and the remaining 65% being dark energy, with the latter two being called “dark” as we don’t understand what they are. Gravitational waves may now provide a tool with which to probe these mysteries in a similar way that X-rays and MRI have allowed us to probe the human body’.

Detecting gravitational waves will help to probe the extreme realms of the cosmos; regions that are otherwise inaccessible to telescopes. Davide Castelvecchi, writing on Nature, highlights six cosmic questions that might be easier to answer in light of this confirmation of gravitational waves.

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While most scientific institutions remain sceptical about time-travel (which some enthusiasts believe could be enabled by study of gravitational waves), there is something just as interesting – perhaps even more so – that could also be reinforced by the LIGO discovery. Scientists have hypothesised for a while that Einstein’s gravitational waves might indicate the likelihood of the multiverse – a greater universe made up of multiple and diverse universes.

Most models of Inflation Theory suggest different parts of that hyper-dense early universe would have expanded at differing speeds, creating ‘bubbles’ of space-time; these ‘bubbles’ would effectively be cut off from one another,resulting in numerous ‘bubble universes’ that co-exist but are unable to interact with each other.

Stanford University theoretical physicist, Professor Andrei Linde (one of the authors of inflationary theory and of the theory of an eternal inflationary multiverse), points to the role of quantum fluctuations being produced during the inflation process and being a cause of galaxy formation. In some places, those quantum fluctuations would be so large that they can produce new and rapidly expanding parts of the universe, the process turning the universe into a multiverse, consisting of many constituent universes with different laws of physics operating in each of them. Says Professor Linde, ‘Every experiment that brings better credence to inflationary theory brings us much closer to hints that the multiverse is real.”

The existence of the multiverse would explain a number of things that presently trouble cosmologists about the nature of our universe and reality.

A classic example often cited by multiverse enthusiasts is the 1998 discovery that galaxies in our universe seem to be spreading apart at an accelerating rate, when their mutual gravitational attraction should be slowing them down. This observation is held to imply the existence of a Dark Energy that counteracts gravity on cosmic scales. The nature of this ‘Dark Side of the Force’ has been a profound mystery for the most part.

Confirmation of a multiverse might also help explain one of the more frustrating paradoxes about our reality, sometimes called the “anthropic” principle: essentially, the fact that we are here to observe the universe at all.

As Dan Vergano notes in this National Geographic article from two years ago; ‘To cosmologists, our universe looks disturbingly fine-tuned for life. Without its Goldilocks-perfect alignment of the physical constants — everything from the strength of the force attaching electrons to atoms to the relative weakness of gravity — planets and suns, biochemistry, and life itself would be impossible. Atoms wouldn’t stick together in a universe with more than four dimensions. If ours was the only cosmos spawned by a Big Bang, these life-friendly properties would seem impossibly unlikely. But in a multiverse containing zillions of universes, a small number of life-friendly ones would arise by chance — and we could just happen to reside in one of them’.

“A multiverse offers one good possible explanation for a lot of the unique observations we have made about our universe,” says the physicist Alan Guth, who first wrote about inflation theory in 1980.

The apparent confirmation of Einstein’s gravitational waves may, according to some scientists, qualify as one of those unique observations that might be construed to support a multi-versal nature to reality.

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