Home Opinions The worldwide and scientific impact of recently observed gravitational waves

The worldwide and scientific impact of recently observed gravitational waves

Illustration by: Maria Tahir | Staff Illustrator

Scientists have observed spacetime ripples known as gravitational waves over 100 years after Albert Einstein theorized their existence, and the world of science is abuzz.

In 1905, an unknown Einstein made a big splash in the physics world by proposing, among other things, the special theory of relativity. Einstein later won the Nobel Prize in physics for his ideas and contributions, but arguably his biggest legacy is the general theory of relativity—his notion on gravity.

Einstein’s theory made previously untenable predictions about the universe. The essence of GR is this: matter tells space how to curve, and space tells matter where to go. Einstein predicted ripples through spacetime should radiate away from gravitational interactions between massive objects—he called these ripples gravitational waves.

In the case of the world’s first discovery of these waves, they came from a collision about 1.3 billion years ago between two black holes, each about 30 times more massive than the sun. Although Einstein’s predictions have come to fruition, GR is not perfect or true in any absolute sense. A scientific theory is only useful if there are experiments to test it, so scientists are constantly pushing the envelope to try and disprove GR. Every theory must fail somewhere. But even the best ones leave room for surprises.

Now, I left out many details in this story because it is important for people to read about it. A scientific endeavor is a human venture more suspenseful than any crime drama, and as humbling as any tragedy. The apparatus that measured the gravitational waves, LIGO, is a phenomenal display of scientific success. Brian Greene gave an impactful and easily digestible explanation of the discovery on “The Late Show with Stephen Colbert.”

Everyone should care about the discovery of gravitational waves, not just scientists or professionals, but the entire world. We should be inspired by their existence. The discovery can be likened to the first person found light, which didn’t actually happen. This is a huge discovery for the human species and it opens up an entirely new way of looking upon the universe. Light can be blocked, but gravity cannot—as far as we can tell.

We are going to use these waves to study ideas never before imagined. The combining of black holes and perhaps even the Big Bang itself are just a couple event that can now be studied again. As Carl Sagan said, “We are a way for the universe to know itself,” and this recent discovery is certainly a new method for the universe to gawk at its own complex beauty.

This is not just a discovery for the physics world, it is a tremendous step forward for the human race because it means we are no longer handicapped by our eyes when asking questions about what we see in the cosmos.


    By Rodney A. Brooks
    author of “Fields of Color: The Theory That Escaped Einstein”.

    The recent discovery of gravitational waves at LIGO (Laser Interferometer Gravitational-Wave Observatory) has grabbed the mind of the public. It will stand as one of the great accomplishments of experimental physics, along with the famous Michelson-Morley study of 1887 which it resembles. In fact by comparing these two experiments, you will discover that understanding gravitational waves is not as hard as you think.

    Contraction. Michaelson and Morley determined the speed of light at varying times as the earth moved around its orbit. To their – and everyone’s – surprise, the speed turned out to be constant, independent of the earth’s motion. This finding caused great consternation until George FitzGerald and Hendrick Lorentz came up with the sole possible explanation: objects in motion compress. Einstein then showed that this reduction is a consequence of his Principles of Relativity, but without saying why they contract (other than a desire to conform to his Principles). In fact Lorentz had previously provided a partial explanation by showing that motion affects the way the electromagnetic field interacts with charges, causing objects to contract. However it wasn’t until Quantum Field Theory came along that a full explanation was found. In QFT, at least in Julian Schwinger’s model, everything is made of fields, even space itself, and motion affects the manner all fields interact.

    Waves. Electromagnetic waves, e.g., radio waves, have long been known and accepted as a natural phenomenon of fields. Now in QFT gravity is a field and, just as an oscillating electron in an antenna sends out radio waves, so a substantial mass moving back and forth will send out gravitational waves. But it didn’t take QFT to show this. Einstein also believed that gravity is a field that obeys his equations, just as the EM field adheres to the equations of James Maxwell. In fact gravitational waves have been accepted by many physicists, from Einstein on down, who see gravity as a field.

    Curvature. But what about “curvature of space-time”, which many people today say is what causes gravity? You may be shocked to learn that’s not how Einstein saw it. He thought that the gravitational field causes things, even space itself, to contract, analogous to the way motion causes contraction. In fact Einstein used this analogy to show the similarity between motion-induced and gravity-induced contraction: they both affect the way fields work together. It is this gravity-induced contraction that is sometimes knowned as “curvature”.

    Evidence. The first detection of gravitational waves was done at LIGO, using a device similar to Michelson’s and Morley’s. In both experiments the time for light to travel along two perpendicular paths was compared, but because the gravitational field is much weaker than the EM field, the distances in the LIGO apparatus are much greater (miles instead of inches). Another difference is that while Michelson, not knowing about motion-induced contraction, anticipated to see a shift (and found none), the LIGO staff used the known gravity-induced contraction to view an alteration when a gravitational wave passed through.

    Fields of Color: The theory that escaped Einstein explains Quantum Field Theory to a lay audience, without any math. If you want to learn more about gravitational waves or about how Quantum Field Theory addresses the paradoxes of Relativity and Quantum Mechanics, read Chapters 1 and 2, which can be seen free at http://quantum-field-theory.net/.

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