Gravitomagnetism is the energy created by spinning objects in the fabric of spacetime. Discover why it may explain away the mysterious Dark Matter for which scientists have been searching unsuccessfully.
When I first took astronomy back in the 1980s, there was a feeling that most of the mysteries about the cosmos were very close to being solved for good. We knew about the Big Bang, for example, and about black holes.
Stephen Hawking and Carl Sagan also explained the nature of the Universe in books and on educational television. It was all mind-blowing, but at the same time, we felt as though science had come very close to finally unlocking the secrets of how our Universe functions.
Nobody told us about a sub-plot to the story. In 1933, astronomer Fritz Zwicky studied the motions within a group of roughly 1,000 galaxies that scientists call the Coma Cluster.
Zwicky’s Estimate was 500 Times Larger Than Hubble’s
Zwicky tried to calculate the mass of these galaxies based on their speed. He then compared his answer to his colleague Edwin Hubble’s estimate of the total number of galaxies and stars in the cluster.
To Zwicky’s surprise, he found that he got a different answer than Hubble. This wasn’t some minor variation. His estimate, based on the motion of the galaxies, was 500 times larger than Hubble’s.
Zwicky referred to his results as “the missing matter.” He also wrote that if his calculations were right, then “dark matter is present in much greater amount than luminous matter.”
“Much Greater Amount than Luminous Matter”
Astrophysicists, including Zwicky, were skeptical about his findings. Even though the discrepancy was enormous, they felt that other influences would soon be uncovered to account for it.
When radio astronomy became common in the 1950s, astronomers continued to confirm the same discrepancy. Scientists were beginning to suspect that either there was a lot more mass in the Universe than anybody knew about or that we don’t fully understand how gravity works.
After I left University in the early 80s, new gravity theories started to emerge that tried to explain the missing matter. Although they offered explanations for some phenomena, they weren’t satisfactory because, overall, they didn’t reconcile the discrepancy as well as Dark Matter models did.
Didn’t Explain It as Well as Dark Matter Models
Now, in the 21st century, we have new techniques for observing distant galaxies. These include gravitational lensing and deep-sky surveys.
These new methods still show an immense discrepancy. The matter we observe still doesn’t come close to providing enough gravity for galaxies to move and interact as they do.
The prevailing wisdom now is that there must be something called “Dark Matter” that we never experience in daily life. Matter is usually made of particles, so Dark Matter must have its own particle type that we haven’t come across yet.
Dark Matter Must Have Its Own Particle Type
These particles wouldn’t interact with light very much, if at all. Yet, they seem to cause gravity, so presumably, they have some sort of mass.
The name scientists came up with for these Dark Matter particles was Weakly Interactive Massive Particles (WIMPs). The trouble is, despite all sorts of well-crafted experiments, nobody has ever seen a trace of anything resembling a WIMP.
This is unsettling because this theory implies that Dark Matter makes up 85% of the matter in the Universe. Cosmologists want to either detect dark matter once and for all or explain the discrepancy some other way. They’re tired of this galactic riddle with no answer.
May Explain Away Dark Matter Altogether
Last week, the European Physics Journal C published a paper that may explain away Dark Matter altogether. Its author argues that we should replace Newton’s laws of motion with Einstein’s Theory of General Relativity. Then, something called gravitomagnetism explains the discrepancy without resorting to unseen Dark Matter.
General Relativity tells us to think of space and time as woven together in a kind of fabric. Any matter inside the fabric of spacetime warps it, and that’s what causes gravity.
Suppose you take an everyday ball and give it an electrical charge. If you spin that ball, it will produce a magnetic field.
Pulls the Fabric of Spacetime With It
Gravitomagnetism works similarly. When an object with mass spins, it pulls the fabric of spacetime with it.
Imagine a spinning ball in a jar of honey. The spinning motion would cause the thick liquid to swirl along with it.
Physicists call this kind of motion “frame-dragging.” This spinning of the spacetime fabric creates a vortex. That releases a type of energy that physicists call gravitomagnetism.
Using Newton’s Laws May Cause the Discrepancy
Gerson Otto Ludwig of the National Institute for Space Research in Brazil is the author of this new research paper. He believes that using Newton’s laws to explain the galaxies’ motions may cause the discrepancy we’ve been discussing.
Professor Ludwig shows that, using General Relativity, the galaxies’ spinning motions create vortices in spacetime’s fabric. These vortices generate gravitomagnetism, which accounts for the extra gravity we’ve been observing since the days of Fritz Zwicky.
Scientists haven’t been taking gravitomagnetism into account because it’s a relatively weak force. Also, its existence was only confirmed in 2011 by NASA’s Gravity Probe B mission.
Gravitomagnetism Seems to Explain Galaxies’ Motions
The significance of Professor Ludwig’s research is that it proves that, even though gravitomagnetism is relatively weak, when it’s factored into the calculations, it seems to explain the motions of the galaxies. Professor Ludwig’s theory appears to account for these movements without looking for the hypothetical missing matter.
Every culture has a story that explains the nature of our Universe and our relationship with it. In today’s world, that story comes to us from science.
Universe Seems to Have a Self-Organizing Property
Increasingly, we’re discovering that the Universe seems to have a self-organizing property based on a not fully understood law of attraction. It’s something we can’t explain yet it holds the galaxies together when, based on our limited understanding, they should be flying apart.
Our story won’t be complete until we account for the discrepancy between the matter we observe and the galactic motions we see. Professor Ludwig’s theory may point us in the right direction to solve this annoying puzzle.
Theory Needs to be Developed Further
Even so, there’s more work to do. Professor Ludwig admits that his theory needs to be developed much further. For example, using his model to explain galaxies’ evolution over time is a complex problem for science to sort out.
For that and other reasons, gravitomagnetism won’t replace Dark Matter as the standard model overnight. Even Professor Ludwig is calling for more in-depth analysis.
Professor Ludwig concluded by writing, “Possibly all calculations performed up-to-date using the thin disk circular velocity model must be reexamined, and the dark matter concept questioned.”
We always have more to learn if we dare to know.
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