Albert Einstein’s Theories of Relativity predicted all kinds of crazy phenomena. First, he discovered that the speed of light is the same for everyone, no matter how fast you are moving. If you are moving in one direction at 99% the speed of light, and you measure the speed of light in any direction, you will get the same answer as you would if you were stationary. Einstein figured out that the reason you experience the speed of light as the same speed no matter what direction or speed you are travelling is that time slows down the faster you go, ultimately stopping when you reach the speed of light. This is called time dilation.
His theory that time slows down has been proven many times by experiment. The worlds global position satellites have clocks on them that run a little bit fast to adjust for Special Relativity and time dilation. Those satellites are travelling around the earth at an extremely high speed. If the clocks on the satellites ran at normal speed, our GPS systems would not be accurate and totally useless within minutes. (Click here to read more about GPS and General Relativity)
He realized that reality itself is bent by the presence of matter, and that more mass equals more curvature of space and reality, and therefore stronger gravity. Black holes were predicted using Einstein’s equations.
Einstein’s theory also predicted a phenomenon called gravitational lensing. This occurs when there is a strong light source behind a very massive object or structure (like a cluster of galaxies) that is warped around the object. This prediction has been proven by experiment many times, and was used as one of the methods to indirectly show the existence of dark matter.
Most recently, an experiment at LIGO (LASER Interferometer Gravitational-Wave Observatory) found what are likely gravitational waves. Einstein predicted that there would be cases where very massive objects like neutron stars or black holes orbit each other, causing reality to be warped in a repeating pattern he called gravitational waves. Recording waves of this nature is important because it may give humans information about the origins of the Universe and may allow us to see further back in time than we can by observing radiation or light. The Universe was opaque until approximately 300,000 years after the big bang, limiting our ability to see into it using conventional radiation detection methods. Gravitational waves are not affected by the clarity of space or the Universe.
The issue for scientists was that gravitational waves would likely only cause very tiny distortions in reality, far to small a distance to measure using conventional measuring tools. They were looking for changes in reality measuring smaller than one million billionth of a millimetre.
The LIGO experiment is very clever. The team of scientists shot a laser into a mirror that split it into two beams, redirecting the beam down two 4km tubes at a right angle to each other. Then, using very reflective material, they bounced the laser back onto itself, positioning the mirrors in such a way that when the beam recombined, it cancelled itself out leaving no signal. If a gravitational wave swept by the experiment, one of the arms would be lengthened and the other squeezed, causing the signal to become unsynchronized, giving the team evidence of gravitational waves.
On September 14, 2015 at 5:51 a.m. Eastern Daylight Time (09:51 UTC), the twin Laser Interferometer Gravitational-wave Observatory (LIGO) detectors, located in Livingston, Louisiana, and Hanford, Washington, USA both measured ripples in the fabric of spacetime – gravitational waves – arriving at the Earth from a cataclysmic event in the distant universe. The new Advanced LIGO detectors had just been brought into operation for their first observing run when the very clear and strong signal was captured.
I’ve always been interested in Physics. I’m lucky to be living in the golden era of physics and quantum mechanics as there are discoveries almost weekly. Gravitational waves were the last remaining prediction by Einstein that had not been proven by experiment. Turns out he was right about everything. And now that the Higgs Boson has been shown to exist, and the Standard Model of Particle Physics is complete, who knows what nature will reveal to us next.