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Category: physics – Page 328

Since Albert Einstein first predicted their existence a century ago, physicists have been on the hunt for gravitational waves, ripples in the fabric of spacetime. That hunt is now over. Gravitational waves exist, and we’ve found them.

That’s according to researchers at the Laser Interferometer Gravitational Wave Observatory (LIGO), who have been holed up for weeks, working round-the-clock to confirm that the very first direct detection of gravitational waves is the real deal. False signals have been detected before, and even though the rumors first reported by Gizmodo have been flying for a month, the LIGO team wanted to be absolutely certain before making an official announcement.

That announcement has just come. Gravitational waves were observed on September 14th, 2015, at 5:51 am ET by both of the LIGO detectors, located in Livingston, Louisiana, and Hanford, Washington. The source? A supermassive black hole collision that took place 1.3 billion years ago. When it occurred, about three times the mass of the sun was converted to energy in a fraction of a second.

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Physicists have been buzzing (or rather, tweeting) about the possibility that the Laser Interferometer Gravitational-Wave Observatory (LIGO) experiment finally discovered gravitational waves. LIGO has been searching for these cosmic ripples for over a decade. Last September, it upgraded to Advanced-LIGO, a more sensitive system that’s also better at filtering out noise. Advanced-LIGO has a much stronger chance of collecting concrete evidence of gravitational waves—if it hasn’t already.

Scientists may be excited, but talk of gravitational waves leaves most people scratching their heads. What are these cosmic vibrations, and why are they making waves in the scientific community?

What are gravitational waves?

Gravitational waves are disturbances in the fabric of spacetime. If you drag your hand through a still pool of water, you’ll notice that waves follow in its path, and spread outward through the pool. According to Albert Einstein, the same thing happens when heavy objects move through spacetime.

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Just last week, we reported that Germany’s revolutionary nuclear fusion machine managed to heat hydrogen gas to 80 million degrees Celsius, and sustain a cloud of hydrogen plasma for a quarter of a second. This was a huge milestone in the decades-long pursuit of controlled nuclear fusion, because if we can produce and hold onto hydrogen plasma for a certain period, we can harness the clean, practically limitless energy that fuels our Sun.

Now physicists in China have announced that their own nuclear fusion machine, called the Experimental Advanced Superconducting Tokamak (EAST), has produced hydrogen plasma at 49.999 million degrees Celsius, and held onto it for an impressive 102 seconds.

While this is nowhere near the hottest temperature that’s been produced by an experiment — that honour goes to the Large Hadron Collider, which hit a whopping 4 trillion degrees Celsius (250,000 times hotter than the centre of the Sun) back in 2012 — the team from China’s Institute of Physical Science in Hefei managed to recreate solar conditions for well over a minute.

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