So much of modern physics relies on indirect observations and theorization. We can't SEE things that happen on a super small or super large scale. Mathematically, we can figure out how things SHOULD happen. But right now, humans just aren't at a point where we have the technology or know-how to "see" far beyond our own solar system, or smaller than the atoms that make us up. Every now and then, though, we have a breakthrough that lets us see that "Yes! Our math has been correct!" Or, "Oops, that didn't quite go according to our predictions..."
When Einstein came out with his Theory of General Relativity, it was based very much on math, theory, and a model of how he thought the universe should work. It's not a law yet--it hasn't been proven beyond a doubt--and there have been some strong arguments against it. But recently, there have been some observations of things in the universe that support his theory, and recently, scientists have found another bit of evidence pointing to the existence of general relativity!
For the first time, scientists have seen, via data from European Southern Observatory's Very Large Telescope and other telescopes, that the orbits of stars around the supermassive black hole in the center of our galaxy show effects predicted by the theory of general relativity, albeit subtly.
Classical physics, the theories put forth by people like Isaac Newton, predict that bodies behave in a certain way. And for the most part, for our intents and purposes as humans on Earth, they DO behave that way. We can calculate the trajectory of a missile launched at a certain speed in a certain direction. We know how hard something is going to hit the ground when it's dropped from a certain height. If I leave station A at one time at a certain speed, and my friend leaves station B at one time at a certain speed, we can figure out where we'd meet. For hundreds of years, we thought that these laws not only governed how things worked on Earth, but how they behaved throughout the whole universe. However, once we started to understand how light travels, and how things behave on a huge scale, beyond what we can directly observe, and started dealing with things that had very large masses, we started to have questions about how things actually behaved versus how they SHOULD behave according to Newton's laws. That's what prompted Einstein's studies. If we account for curved space-time of general relativity, physics behaves differently than in a "planar" system. We can see these effects in our own solar system, as well as in larger systems.
One of the stars orbiting the central black hole in the Milky Way, S2, exhibited a tiny change in motion in its orbit, a change that is consistent with how Einstein predicted general relativity would affect a body in orbit around a supermassive object. This is the first time scientists have observed this effect, and it's pretty exciting to see decades of laboratory and simulation work exhibited by actual objects in the galaxy.
Until now, scientists haven't been able to make these observations. They lacked the equipment necessary to make the ultra-accurate measurements in star positions necessary to make any judgments. But now, thanks to the Very Large Telescope's near-infrared adaptive optics instruments, scientists could measure S2's position both in its orbit close to the black hole, and when it was further away.
"During the course of our analysis, we realized that to determine relativistic effects for S2, one definitely needs to know the full orbit to very high precision," team leader Andreas Eckart at the University of Cologne said. Analysis of the data from the VLT has given scientists this more precise information, as well as more information about the black hole itself.
"It is very reassuring that S2 shows relativistic effects as expected on the basis of its proximity to the extreme mass concentration at the center of the Milky Way. This opens up an avenue for more theory and experiments in this sector of science," says Vladimir Karas from the Academy of Sciences in Prague, the Czech Republic.
This observation is just the beginning! In 2018, the star S2 will be making a very close approach to the supermassive black hole in the center of the Milky Way, and scientists plan on using the new GRAVITY instrument installed on the Very Large Telescope to help measure the orbit much more precisely than is now possible. This will not only help scientists make more accurate readings, but could help them see deviations from general relativity that could help us understand even MORE physics!
Melanie R. Meadors is an author of fantasy where heroes don't always carry swords and knights in shining armor often lose to nerds who study their weaknesses. She has edited two upcoming genre anthologies, MECH: Age of Steel and HATH NO FURY, and is the science and pop culture blogger at The Once and Future Podcast. You can find her at her website, melaniermeadors.com, on Facebook, and Twitter, @melaniermeadors.