Guide to the Cosmos

    Making the Wonders of Our Universe Accessible to Everyone

Newsletter: Einstein Proven Right ... Again

Astronomers have once again confirmed Einstein’s Theory of General Relativity, this time by studying the decaying orbits of a pair of white dwarf stars.
Einstein predicted that massive objects “bend the fabric” of space and time, creating the effect we call gravity. One can visualize this by imaging a taut bed sheet with a bowling ball on its center. The bowling ball would warp the bed sheet, creating a curved surface that affects the motion of anything that rolls across it. The illustration below suggests how our Sun warps the space and time of our solar system, causing the Earth to move in a circle just as a marble might roll around the inside of a salad bowl. Einstein said the Sun doesn’t pull on Earth, as with an invisible rope, but rather the Earth is moving along the straightest path in the curved space created by the Sun.



Now imagine a spinning barbell in the middle of a bed sheet. The shape of the bed sheet would constantly change — ripples would move out from the center as the barbell turned. Something similar happens when two massive white dwarf stars orbit one another, and we call these ripples in the fabric of spacetime “gravity waves.” Einstein’s Theory of General Relativity, which supersedes Newton’s theory of gravity, exactly predicts the amount of energy carried away by gravity waves. Because energy is conserved (its total amount never changes), the energy that the gravity waves carry away has to come from somewhere. In this case, the orbiting stars lose energy and spiral closer, which reduces their orbital period (the time required to complete an entire orbit). Eventually the white dwarfs will merge, possibly forming a neutron star or black hole.
Starting in 1974, two American astronomers, Russell Hulse and Joseph Taylor, observed the decreasing period of a pair of orbiting neutron stars. They received the 1993 Nobel Prize for their exquisitely precise measurements, which confirmed Einstein’s theory.
The new observation was performed by astronomers from Harvard-Smithsonian, University of Texas, and the Astrophysics Institute of the Canary Islands. They studied two white dwarfs that orbit one another in less than 13 minutes — 765.20654 ± 0.00005 seconds to be precise. Below is an artist’s sketch produced by NASA of this binary system, identified as J0651, which lies 3000 light-years away (18,000 trillion miles). White dwarfs are the final stage, the collapsed remnants, of the least massive and most common stars.


The orbital plane of this binary system just happens to align with our line of sight, making it particularly easy to make precise measurements as the stars eclipse one another.
The masses of white dwarfs in this binary system are each 125% of our Sun’s mass. For the mass and orbital values of this system, Einstein’s theory predicts the orbital period will decrease by 0.000,26 seconds per year. The observed decrease is 0.000,31 seconds per year with a measurement uncertainty of ±0.000,10. Thus theory and observation agree well within the measurement precision, confirming Einstein’s prediction. Over the coming years ever more precise measurements will be made on this system. I’ll gladly wager that Einstein’s theory will hold up.
Let’s stop to consider how remarkable this really is.
Imagine some guy, an unknown government clerk, sitting at a desk, with only paper and pen. He didn’t have a computer or a telescope and could only ponder what might be out in the great beyond. At that time, no one knew anything about white dwarfs or neutron stars; no one even knew what a neutron was or that stars collapsed when they died. Yet, Einstein was able to precisely calculate what would happen to such enormous celestial bodies trillions of miles away.
That’s true genius — a testament to the power of the human mind. Remember, your DNA is 99.9% the same as Einstein.
We can all do amazing things.
Best Regards,
October 15, 2012
Note: Previous newsletters can be found on my website.



Dr. Robert Piccioni
Author of "Everyone's Guide to Atoms, Einstein, and the Universe",
"Can Life Be Merely An Accident?"

& "A World Without Einstein"