LSA Honors Physics 2016/7: Gravitational Waves

Gravitational Waves

The Discovery:

The discovery of gravitational waves has been declared the breakthrough of the year
Physicists announced they heard the subtle rumbling of a ripple in spacetime which is the result of two black holes colliding
These observations confirmed the existence of gravitational waves
These waves were predicted by Albert Einstein more than 100 years ago
The waves were picked up by two huge science experiments called the Laser Interferometer Gravitational-Wave Observatory
This discovery launched a whole new branch of science
Right now, our telescopes can only see objects that emit electromagnetic radiation (visible light, X-rays, gamma rays)
Some objects like colliding black holes, don't emit any electromagnetic radiation but they do emit gravity. So with gravitational wave astronomy, invisible objects in the universe may soon become visible

Why the waves matter:

Just as sound waves disturb the air to make noise, gravitational waves disturb the fabric of spacetime to push and pull matter as if it existed in a funhouse mirror
If a gravitational wave passed through you, you’d see one of your arms grow longer than the other. If you were wearing a watch on each wrist, you'd see them tick out of sync
Gravitational waves are generated by any movement of mass
The only way to detect gravitational waves that faint is from a really loud source like the collision of two black holes
Two black holes colliding unleash a loud thunderclap of gravity. But by the time they reach Earth 1.4 billion years later, they are not as loud
This compares to how pond ripples become less frenzied farther away from a dropped stones
Gravitational waves are comparable to the frequencies of the sound waves we hear
One of the waves heard was around 0.7 attometers tall, much smaller than an atom

How the Experiment is conducted:

There are two massive experiments, both are giant L-shaped tubes. Each arm of the tube is 2.5 miles long
During the experiments, a laser beam is equally split between the two arms. At the end of each arm is a mirror, which reflects the laser back to the starting point
Scientists are looking for evidence that gravitational waves are distorting spacetime enough that one of the arms becomes temporarily longer than the other

Facts About Gravitational Wave Astronomy:

Scientist can’t just point at a region in the sky to search for gravitational waves, they can just hear the gravitational waves that are passing through Earth at any particular moment
The area where the waves are coming from is hard to determine
Gravitational wave astronomy could accomplish

If you look with visible light as far as we can look in the universe, the universe is no longer transparent, instead it is opaque

Physicists have speculated that the theory isn’t complete
Gravitational waves could help physicists put general relativity to harder and harder tests to see where it fails

Neutron stars are the extremely dense cores of collapsed stars that can emit large amounts of gravity

Gravitational wave astronomy will help us understand how many of these pairs exist in the universe

Dark matter is theorized to make up 27 percent of all the matter in the universe.
Matter creates gravity
Perhaps gravitational waves can help us trace the origins of dark matter

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