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  • Writer's pictureNick Cook

Riding a Gravity Wave Across the Universe

(Article Originally Published 19/2/2016)

“I have no special talents. I am only passionately curious.”

― Albert Einstein

Over the last two weeks, you have probably picked up on the considerable excitement in the news over the confirmation of the existence of gravity wave. So why all the fuss?

Gravity waves were first predicted by Albert Einstein’s general theory of relativity over a century ago. Einstein postulated that objects like planets and stars, warp space time through their gravitational force. The classic illustration of this is a stretched piece of rubber onto which heavy spheres (representing planets, etc) are placed. The objects deform the rubber sheet into a valley around them, much like gravity warps the space time field. And it this which holds a moon in locked in orbit around its planet, and a planet around its star, all whirling in a never ending celestial dance. However, as predicted by Einstein, time is also being effected.

If you think time is a constant in our world, be prepared for a shock. Believe it or not, time varies depending on where you are. At the bottom of a tall skyscraper time will be running more slowly than it does at the top. Even if this feels counterintuitive, this phenomena is proven every single day with the GPS satellites in orbit over our planet. These satellites run atomic clocks for absolute accuracy. The problem is that they drift out of sync with our ground based atomic clocks. Why? Because time is actually running faster at the height of their orbit. This means that everyday their clocks have to be synched again.

This same effect on time also plays out with gravitational waves. When two massively heavy gravitational objects collide, like black holes, this creates an event that sends out massive ripples across the fabric of space time. Imagine a heavy object being dropped onto that sheet of rubber with our planet objects on it. The ripples, like from a stone thrown into a pond, spread out and disturb the other objects on the rubber sheet. And it’s this effect from two distant colliding black holes upon the fabric of space time, that's been measured and now confirmed by scientists using the Laser Interferometer Gravitational-wave Observatory (LIGO).

By firing lasers down long perpendicular tunnels in Washington and Louisiana, scientists have been able to detect the gravity ripple of those colliding black holes, passing through the Earth. But what did they measure exactly?

For a very brief moment the distance measured in the tunnels by the lasers of LIGO, changed as that gravity wave hits us. For a fleeting moment the gravity effect measured, was greater than that of all the stars of entire visible universe upon the Earth, albeit with the tinniest change in distance! And in that moment our whole planet, and us along with it, was stretched and squashed by that same gravity wave.

In a stroke Einstein’s theory was proven. Not only that. We now have direct evidence that black holes really exist. Additionally, this discovery opens up an exciting avenue for a new form of gravity astronomy, measuring objects like merging neutron stars, gravitational echoes of the big bang, discovering other black holes, etc.

The confirmation of the existence of gravity waves heralds a whole new era of understanding of our universe. No wonder so many scientists are so excited about the implications of this pivotal moment in science.

Photo via Visualhunt

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