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Physicists keep trying to break the rules of gravity but this supermassive black hole just said 'no'

The first ever direct image of a black hole, with yellow ring surrounding black circle
This is the first ever direct image of a black hole, with yellow ring surrounding a black circle. A new analysis of that inner shadow has reaffirmed Einstein's theory of gravity.
(Image: © Event Horizon Telescope Collaboration)

 

A new test of Albert Einstein's theory of general relativity has proved the iconic physicist right again — this time by re-analyzing the famous first-ever picture of a black hole , which was released in April 2019.

That image of the supermassive black hole at the center of galaxy M87 was the first direct observation of a black hole's shadow — the imprint of the event horizon, a sphere around the black hole's singularity from which no light can escape. Einstein's theory predicts the size of the event horizon based on the mass of the black hole; and in April 2019, it was already clear that the shadow fits general relativity's prediction pretty well. 

But now, using a new technique to analyze the image, the researchers who made the picture showed just how well the shadow fits the theory. The answer: 500 times better than any test of relativity done in our solar system. That result, in turn, puts tighter limits on any theory that would seek to reconcile general relativity, which describes the behavior of massive celestial objects, with quantum mechanics, which predicts the behavior of very small things. 

General relativity's great accomplishment was to describe how gravity operates in the universe: how it pulls objects toward each other; how it warps space-time; and how it forms black holes. To test general relativity, scientists use the theory to predict how gravity will act in a certain situation. Then, they observe what actually happens. If the prediction matches the observation, general relativity has passed its test.

But no test is perfect. Watch how the sun's gravity tugs Mercury along its orbit, and you can measure general relativity in action. But telescopes can't measure the movement of Mercury down to the nanometer. And other forces — the tug of Jupiter's gravity, and Earth's gravity and the force solar wind, to name just a few — impact Mercury's movement in ways that are difficult to separate from the effects of relativity. So the result of every test is an approximation and Einstein's theory is only proven more or less.

Related: 8 ways you can see Einstein's Theory of Relativity in real life

The size of that uncertainty — the "more or less" factor — is important. When scientists test general relativity over and over, they are putting constraints on Einstein's idea. The reason this work is important is that even though general relativity keeps passing tests, physicists do expect it to eventually fail.

General relativity must be incomplete, physicists believe, because it contradicts quantum mechanics. Physicists believe that discrepancy signals the presence in our universe of some larger, all-encompassing mechanism describing both gravity and the quantum world that they have yet to uncover. Looking for cracks in relativity, they hope, might turn up clues to help them find that complete theory."We expect a complete theory of gravity to be different from general relativity, but there are many ways one can modify it," University of Arizona astrophysicist Dimitrios Psaltis said in a statement. Psaltis is lead author of a paper published Oct. 1 in the journal Physical Review Letters describing this new test, and is part of the Event Horizon Telescope (EHT) team, responsible for imaging the M87 black hole's shadow.

In this new test, Psaltis and colleagues used a computer to generate artificial images of the M87 black hole based on a modified version of gravity, where the force of gravity is weaker or stronger at the event horizon. With that weakened-gravity scenario, they asked,how large or small would that black hole's event horizon be? What about with stronger gravity? Then, they checked how many of those possible modifications produced event horizons with sizes that matched that of the image EHT actually captured of M87. Some did, their slight variances from general relativity's predictions much too small to show up in the admittedly fuzzy snap of the black hole. But the vast majority did not.

Related: The 12 strangest objects in the universe

"Using the gauge we developed, we showed that the measured size of the black hole shadow in M87 tightens the wiggle room for modifications to Einstein's theory of general relativity by almost a factor of 500, compared to previous tests in the solar system," University of Arizona astrophysicist Feryal Özel, another study co-author and EHT scientist, said in the statement. 

Most alternative ways that gravity might work that they considered — theories that violate Einstein's general relativity — don't fit within this newly narrowed wiggle room.

In the future, the EHT researchers said, they might be able to tighten that wiggle room even further.

The EHT is a network of radio telescopes all over the world that work together to produce the sharpest possible images of supermassive black holes — objects that, while large, are much too small and dim for any one telescope to resolve on its own. So far, the EHT has just published one image of one black hole, in M87. But there's another, smaller black hole in our own neighborhood that the collaboration should be able to image: Sagittarius A*, the supermassive at the center of the Milky Way.

As the EHT has trained its army of radio telescopes on this more nearby target, they've refined their theoretical technique and added new telescopes to the collaboration. The next image they produce, they say, should constrain general relativity even further.

Or maybe they'll see something Einstein didn't predict at all.

Originally published on Live Science.

  • Xinhang Shen
    Dear Rafi Letzter, please be aware that Einstein's relativity has already been disproved for more than four years both experimentally and theoretically. There is no such thing called spacetime in nature, not to mention the existence of its singularities because our physical time measured with physical clocks is absolute and independent of the 3D space.

    The most reliable and well-known experimental evidence for the absolute time is that the atomic clocks on the GPS satellites, after corrections, are synchronized to show the same absolute time relative to all reference frames (the ground frame, the satellite frames, etc), while special relativity claims that time is relative and thus clocks can never be synchronized relative to more than one inertial reference frame no matter how you correct them.

    Einstein made a fatal mistake in his special relativity. He postulates that the speed of light should be the same relative to all inertial reference frames, which forces the change of the definition of space and time. But he never verified that the newly defined time was still the time measured with physical clocks. Please be aware that our physical time i.e. clock time won't change with the change of the definition of the space and time. Actually, the newly defined relativistic time is indeed not the time measured with physical clocks any longer. It is just a mathematical variable without physical meaning, which can be easily verified as follows:

    We know physical time T has a relationship with the relativistic time t in Einstein's special relativity: T = tf/k where f is the relativistic frequency of the clock and k is a calibration constant, that is, a clock uses the change of the status of a physical process to indirectly measure time. Now We would like to use the behavior of our physical time in Lorentz Transformation to demonstrate that the relativistic time t defined by Lorentz Transformation is no longer our physical time T.

    If you have a clock (clock 1) with you and watch my clock (clock 2) in motion and both clocks are set to be synchronized to show the same physical time T relative to your inertial reference frame at relativistic time t, you will see your clock time: T1 = tf1/k1 = T and my clock time: T2 = tf2/k2 = T, where t is the relativistic time of your reference frame, f1 and f2 are the relativistic frequencies of clock 1 and clock 2 respectively, k1 and k2 are calibration constants of the clocks. The two events (Clock1, T1=T, x1=0, y1=0, z1=0, t1=t) and (Clock2, T2=T, x2=vt, y2=0, z2=0, t2=t) are simultaneous measured with both relativistic time t and clock time T in your reference frame. When these two clocks are observed by me in the moving inertial reference frame, according to special relativity, we can use Lorentz Transformation to get the events in my frame (x', y', z', t'): (clock1, T1', x1'=-vt1', y1'=0, z1'=0, t1'=t/γ) and (clock2, T2', x2'=0, y2'=0, z2'=0, t2'=γt), where T1' = t1'f1'/k1 = (t/γ)(γf1)/k1 = tf1/k1 = T1 = T and T2' = t2'f2'/k2 = (γt)(f2/γ)/k2 = tf2/k2 = T2 = T, where γ = 1/sqrt(1-v^2/c^2). That is, no matter observed from which inertial reference frame, the events are still simultaneous measured with physical time T i.e. the two clocks are always synchronized measured with physical time T, but not synchronized measured with relativistic time t'. Therefore, our physical time and the relativistic time behave differently in Lorentz Transformation and thus they are not the same thing. The change of the reference frame only makes changes of the relativistic time from t to t' and the relativistic frequency from f to f', which cancel each other in the formula: T = tf/k to make the physical time T unchanged i.e. our physical time is still absolute in special relativity. Based on the artificial relativistic time, special relativity is wrong, so is general relativity. There is no such thing called spacetime in nature, not to mention the expansion, singularities, ripples of spacetime. For more details, please check:

    https://www.researchgate.net/publication/297527784_Challenge_to_the_Special_Theory_of_Relativity
    Reply
  • Bob Mogy
    Xinhang Shen said:
    Einstein made a fatal mistake in his special relativity. He postulates that the speed of light should be the same relative to all inertial reference frames
    Dude, constant speed of light is a consequence of Maxwell's equations and was known before Einstein. Before arguing with fundamentals you probably should learn them first.
    Reply
  • Xinhang Shen
    Bob Mogy said:
    Dude, constant speed of light is a consequence of Maxwell's equations and was known before Einstein. Before arguing with fundamentals you probably should learn them first.
    Don't assume that people don't know such simple thing. Actually I would remind you that you should not make any irresponsible comment before understanding what I presented here. Please read it carefully. If you find any error in my reasoning, please refute it and let's have a rational debate.

    The disproof of special relativity means the existence of aether - a fluid medium for all electromagnetic phenomena. Regarding Maxwell's equations, please be aware that there is no electric field and no magnetic field in nature. These are just direct modelings of the forces on a charged particle exerted by aether, which are similar to the forces on an airplane exerted by air where you can't find resistance field and lift field but just air flow field. The speed of light can be isotropic only relative to aether, the same as the speed of sound can be isotropic only relative to air.
    Reply
  • Bob Mogy
    Xinhang Shen said:
    Don't ... you should not ... read ... let's have ...
    You should not put so many imperatives in one paragraph when you address me. I will do whatever I want that is within the rules of this forum. In order to have a rational debate with me you must possess the fundamental knowledge equal to mine. You don't. If you are going to be modest and humble, and ask the right question instead of making claims that the science is wrong, I might be able to explain to you how the things really are, though I am not sure, the prognosis is bad.

    Synchronization of GPS clocks works only for Earth surface. You can't do it for any reference frame. If you breath when you sleep, it doesn't mean you sleep when you breath. (C) Lewis Carroll. It's simple logic. I suggest for you to practice in using it.
    Reply
  • bestwork1989
    admin said:
    A new test of Albert Einstein's theory of general relativity has proved the 20th Century physicist right again, this time using a supermassive black hole.

    Physicists keep trying to break the rules of gravity but this supermassive black hole just said 'no' : Read more
    hi you are talking about A new test of Albert Einstein's theory of general relativity.There is no such thing called spacetime in nature . but there is probability of experiment where we can get some more idea about universe.


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  • Xinhang Shen
    Bob Mogy said:
    Synchronization of GPS clocks works only for Earth surface. You can't do it for any reference frame.

    Please see GPS on Wikipedia: "The GPS concept is based on time and the known position of GPS specialized satellites. The satellites carry very stable atomic clocks that are synchronized with one another and with the ground clocks. " you can't deny the fact.
    Reply
  • efarina96
    General Relativity is an understanding on ofur finite perception of our universe, which in reality is part of a chain of singularities with observable finite properties "culminating" in eternity. What is observed from beyond as a singularity with finite properties such as mass, spin, charge, and observable boundary, is observed from within as the physics of an infinite universe. This is because every existence, while appearing to be finite, is actually just a finite experience of an infinite singularity constrained by the limited spees of light. Simple.
    Reply
  • efarina96
    *speed
    Reply
  • efarina96
    Sorry for the typos but the point is quite simple. Wave-particle duality is a reflection of the possibilities intiated by observation relative to infinity and constrained by choice.
    Reply
  • efarina96
    There is nothing "before" the Big Bang, but rather an infinite singularity "beyond" the Big Bang that cannot be described in finite terms of time. Again, simple.
    Reply