CONTROVERSIAL TOPICS

CONTROVERSIAL TOPICS

Wednesday, August 23, 2017





A new type of gravitational wave caused by the collision of two stars may have been seen for the first time in a breakthrough that could help unravel the secrets of the universe

  • Rumours of the potentially enormous discovery began after a single tweet 
  • Astronomer J Craig Wheeler of the University of Texas sparked the speculation
  • The Ligo observatory has previously detected waves created by black holes
  • The latest waves are believed to originate in a galaxy called NGC 4993
  • They would allow physicists to observe the effect in visible light for the first time



A new type of gravitational wave - which are ripples through space-time predicted by Albert Einstein a century ago - may have been detected.
Scientists first detected the shudders in the fabric of the universe last year and the discovery was hailed the 'biggest scientific breakthrough of the century'.
Now speculation is growing that a previously undiscovered form of the waves, created by the collision of two neutron stars, may have been found. 
If true, this would mark the first time that physicists could observe gravitational waves directly in visible light.
This is an important discovery as it opens up a new way of studying the universe and unravelling mysteries such as the nature of dark energy.

Speculation is growing that a previously undiscovered form of gravitational wave, created by the collision of two neutron stars (pictured), may have been found. If true, this would mark the first time physicists have observed gravitational waves directly in visible light (stock image)
Speculation is growing that a previously undiscovered form of gravitational wave, created by the collision of two neutron stars (pictured), may have been found. If true, this would mark the first time physicists have observed gravitational waves directly in visible light (stock image)

NEUTRON STARS 

Neutron stars are the small, dense remains of a once-massive star that exploded as a powerful supernova at the end of its natural life.
They often spin very rapidly and can sweep regular pulses of radiation towards Earth, like a lighthouse beacon appearing to flash on and off as it rotates.
These 'pulsars' can be found in stellar couples, with the neutron star cannibalising its neighbour.
This can lead to the neutron star spinning faster, and to pulses of high-energy X-rays from hot gas being funnelled down magnetic fields on to the neutron star.

Rumours of the potentially enormous discovery began after a single tweet sent by astronomer J Craig Wheeler of the University of Texas at Austin according to reports in New Scientist.
He tweeted: 'New Ligo. Source with optical counterpart. Blow your sox off!'
That was enough to fuel supposition that researchers at the Laser Interferometer Gravitational-Wave Observatory (Ligo), may have uncovered evidence of one of the universe's most violent events. 
Ligo, the world's largest gravitational wave observatory, has previously recorded gravitational waves from three massive explosions.
On these occasions, the waves were created by black holes smashing together with enormous energy.
Since that time, the US-based Ligo physics experiment has been collaborating with the Virgo observatory in Europe to increase their detection sensitivity.
At a press conference, Ligo researchers previously spoke of their ambition to use the facility to detect neutron stars.
It is believed that their efforts have paid off, with Mr Wheeler's tweet thought to refer to gravitational waves from neutron stars.  
That is because waves created by black holes can not be seen in visible wavelengths, unlike neutron stars which do produce 'optical' output when they collide.
Both Ligo and Virgo use lasers to measure tiny variations caused by passing gravitational waves.
The Laser Interferometer Gravitational-Wave Observatory has previously recorded gravitational waves (pictured) from three massive explosions. On these occasions, the waves were created by black holes smashing together with enormous energy (artist's impression)
The Laser Interferometer Gravitational-Wave Observatory has previously recorded gravitational waves (pictured) from three massive explosions. On these occasions, the waves were created by black holes smashing together with enormous energy (artist's impression)
Scientists at optical observatories are now reportedly working to point their telescopes at the galaxy where the latest signal is thought to have originated. 
Their efforts are thought to be focused a galaxy around 130 million light years away in the Hydra constellation, called NGC 4993.
It contains a pair of entwined neutron stars which could be responsible for producing the waves. 
In all three previous cases, each of the twin detectors of Ligo detected gravitational waves from the energetic mergers of black hole pairs.

WHAT ARE GRAVITATIONAL WAVES? 

Scientists view the the universe as being made up of a 'fabric of space-time'.
This corresponds to Einstein's General Theory of Relativity, published in 1916.
Objects in the universe bend this fabric, and more massive objects bend it more.
Gravitational waves are considered ripples in this fabric.
Gravitational waves are considered ripples in the fabric of spacetime. They can be produced, for instance, when black holes orbit each other or by the merging of galaxies
Gravitational waves are considered ripples in the fabric of spacetime. They can be produced, for instance, when black holes orbit each other or by the merging of galaxies
They can be produced, for instance, when black holes orbit each other or by the merging of galaxies.
Gravitational waves are also thought to have been produced during the Big Bang.
If found, they would not only confirm the Big Bang theory but also offer insights into fundamental physics.
For instance, they could shed light on the idea that, at one point, most or all of the forces of nature were combined into a single force. 
In March 2014, a team operating the Bicep2 telescope, based near the South Pole, believed they had found gravitational waves, but their results were proven to be inaccurate.These are collisions that produce more power than is radiated as light by all the stars and galaxies in the universe at any given time.
The most recent detection, announced in June, appears to be the farthest yet, with the black holes located about three billion light-years away.
Scientists said gravitational waves open a 'new door' for observing the universe and gaining knowledge about enigmatic objects like black holes and neutron stars.
Understanding such astronomical phenomena could be useful in helping us decipher how the universe first came to be. 
'This [discovery is taking us deeper into time and space in ways we couldn't do before the detection of gravitational waves,' said France C√≥rdova, director of the National Science Foundation.
How our sun and Earth warp space and time, or spacetime, is represented here with a green grid, as  described Albert Einstein in his General Theory of Relativity in 1916
How our sun and Earth warp space and time, or spacetime, is represented here with a green grid, as described Albert Einstein in his General Theory of Relativity in 1916

HOW DOES LIGO WORK? 

The LIGO detectors are interferometers that shine a laser through a vacuum down two arms in the shape of an L that are each 4 kilometers in length.
The light from the laser bounces back and forth between mirrors on each end of the L. Scientists measure the length of both arms using the light.
If there's a disturbance in space-time, such as a gravitational wave, the time the light takes to travel 4 kilometers will be slightly different in each arm making one arm look longer than the other.
LIGO scientists measure the interference in the two beams of light when they come back to meet, which reveals information on the space-time disturbance.'In this case, we're exploring approximately three billion light-years away. 
'Ligo continues to make remarkable discoveries, transitioning from experiment to gravitational wave observatory. 
'More importantly each detection has offered much more than just a sighting.
'Slowly, we are collecting data that unveil the origin and characteristics of these objects, further informing our understanding of the universe.' 
The June observation also provided clues about the directions in which the black holes are spinning.
As pairs of black holes spiral around each other, they also spin on their own axes, much like a pair of ice skaters spinning individually while also circling around each other.
Sometimes black holes spin in the same overall orbital direction as the pair is moving, this is known as aligned spins, and sometimes they spin in the opposite direction of the orbital motion.
And black holes can also be tilted away from the orbital plane. 
The new Ligo data implies that at least one of the black holes may have been non-aligned compared to the overall orbital motion.
More observations ware needed to say anything definitive about the spins of binary black holes, but these early data offer clues about how these pairs may form.

WHAT IS THE THEORY OF RELATIVITY? 

Gravitational waves were predicted under Albert Einstein's (pictured) General Theory of Relativity in 1916
Gravitational waves were predicted under Albert Einstein's (pictured) General Theory of Relativity in 1916
In 1905, Albert Einstein determined that the laws of physics are the same for all non-accelerating observers, and that the speed of light in a vacuum was independent of the motion of all observers - known as the theory of special relativity.
This groundbreaking work introduced a new framework for all of physics, and proposed new concepts of space and time.
He then spent 10 years trying to include acceleration in the theory, finally publishing his theory of general relativity in 1915.
This determined that massive objects cause a distortion in space-time, which is felt as gravity.
At its simplest, it can be thought of as a giant rubber sheet with a bowling ball in the centre.
As the ball warps the sheet, a planet bends the fabric of space-time, creating the force that we feel as gravity.
Any object that comes near to the body falls towards it because of the effect.
The theory was most recently demonstrated in the hit film film Interstellar (pictured), in a segment that saw the crew visit a planet which fell within the gravitational grasp of a huge black hole, causing time to slow down massively
The theory was most recently demonstrated in the hit film film Interstellar (pictured), in a segment that saw the crew visit a planet which fell within the gravitational grasp of a huge black hole, causing time to slow down massively
Einstein predicted that if two massive bodies came together it would create such a huge ripple in space time that it should be detectable on Earth.
It was most recently demonstrated in the hit film film Interstellar.
In a segment that saw the crew visit a planet which fell within the gravitational grasp of a huge black hole, the event caused time to slow down massively.
Crew members on the planet barely aged while those on the ship were decades older on their return

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