Einstein’s theory of General Relativity offers a model of space that envisions gravitational forces as curvatures in space caused by the presence of masses – rather than as forces acting across a distance. The more massive an object is, the more it distorts and warps the surrounding space-time fabric, the same way a bowling ball, a baseball and a marble resting on a trampoline will each distort it a different amount. A ping-pong ball on the trampoline that rolls towards a bowling ball isn’t attracted to it, it’s just following the curves of the trampoline.
Now, many decades after Einstein’s ideas first altered the way people understood and described the universe, scientists can collect actual data and compare observations to the predictions posed by Einstein’s theories. Already, several predictions that were radical when Einstein made them have turned out to be true: the expansion of space, the existence of black holes, and the presence of some kind of universal energy pulling matter apart.
This video describes a new NASA mission that will observe the energy being released from matter falling into a black hole. A black hole is an object so incredibly dense that nothing can escape, not even light. Its gravitational forces create an “event horizon” inside of which – to an outside observer – time seems to stop. Any matter near a black hole will be subject to its intense gravity. As the matter is pulled to the center of the black hole, it releases high energy radiation that can be detected and mapped.
Near a black hole, gravitational forces are so intense that space-time gets highly warped. Based on the radiation signatures of matter moving through these areas, we can observe the warping – and can track what scientists refer to as “gravity waves.” Gravity waves don’t work the same way as electromagnetic (EM) waves; they represent a completely different idea. Gravity waves arise when matter changes or is accelerated. They are “ripples” in space-time. Only now - as our technology, design and engineering have sufficiently advanced – can we probe for actual data about gravity waves and see if, once again, Einstein’s predictions were correct.
Dr. Richard Mushotzky: Black holes are the strongest test of what the theory of gravity really is. Space is just bent and warped and twisted in some incredibly complex way and if one could only understand that one would have a fundamental insight into the theory of gravity.
Dr. Kimberly Weaver: In the past five years our knowledge of black holes has really exploded. By using space based and ground based telescopes covering the full electromagnetic spectrum, astronomers have found that black holes are everywhere. They come in a variety of sizes and they are integral to the formation of galaxies. One way to find a black hole is to look for x-rays that are produced by matter caught up in its violent and extreme environment. In fact, we are extremely close to looking at the edge of a black hole – something Einstein never imagined.
Narration: What happens to matter and energy as it moves closer to a black hole and crosses the event horizon, the theoretical border from which nothing can escape? Does time really come to a standstill? Will we see a breakdown in general relativity in the environment of extreme gravity? General relativity makes specific predictions about matter and energy close to a black hole. If upon close scrutiny we see the slightest deviation between theory and observation we will understand limitations in Einstein’s equations. Two space missions will take us closer to a black hole event horizon that we’ve ever been. LISA, a joint NASA European mission now in formulation will listen for gravitational waves created by merging black holes.
Dr. Robin “Tuck” Stebbins: Now we’re talking about opening a window that’s not even based on electromagnetism. It’s a window that’s based on gravitational radiation.
Dr. David Spergel: The gravity wave spectrum is kind of a new and really unexplored frontier. No one’s directly detected gravity waves. As we start to open up this next frontier, which I think many of us think of as the Great Frontier for the 21st century astronomy, I think we’re going to learn about different parts of that spectrum.
Narration: Another mission will give us a closer look at black holes and probe the mystery of dark energy. Constellation X, an x-ray observatory, will make movies of the material falling into a black hole, to map the warping of space time.
Dr. Kimberly Weaver: Constellation X will let us watch how that matter approaches the event horizon and how from our perspective, time creeps to a halt. We’ll be able to watch the final x-ray flicker of light as matter plunges into the black hole and disappears forever. This is where we’ll be able to probe the most extreme conditions of gravity that we know of and really put Einstein’s theories to the test.
Narration: Einstein hoped to fold the quantum force of electromagnetism into general relativity and to find a uniform theory. Much of what he could not answer and struggled with until the day he died remains unanswered today. These questions about dark energy, black holes, the big bang, and the nature of gravity have come to define the cutting edge.
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