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Category: physics – Page 318

But now it seems that collision may have been followed by a bright burst of gamma rays. NASA’s Fermi gamma-ray space telescope detected such an eruption just 0.4 seconds after LIGO’s gravitational waves arrived at Earth. It’s not clear whether the same event triggered both signals, but the Fermi team calculated that the probability of a coincidence was just 0.0022.

The problem is that no one expected such a bright gamma-ray burst to accompany a black-hole merger. Coalescing black holes orbit each other in a cosmic do-si-do, clearing out a region of empty space. According to models of gamma-ray bursts, isolated black holes can’t ignite them.

Strange signal

“Everything smells like a short gamma-ray burst in our signal,” says Valerie Connaughton of the Fermi team. “And that’s a real problem in a way – you don’t expect this signal from merging black holes.”

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Physicists working with a powerful observatory on Earth announced Thursday that they have finally detected ripples in space and time created by two colliding black holes, confirming a prediction made by Albert Einstein 100 years ago.

These ripples in the fabric of space-time, called gravitational waves, were created by the merger of two massive black holes 1.3 billion years ago. The Laser Interferometer Gravitational-Wave Observatory (LIGO) on Earth detected them on Sept. 14, 2015, and scientists evaluated their findings and put them through the peer review process before publicly disclosing the landmark discovery today.

SEE ALSO: Einstein was right: Scientists detect gravitational waves for the first time.

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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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