Could gravity exist without mass? According to astrophysicist Richard Liu, it is possible. And that would solve the still-mysterious problem of dark matter.
In the 17th century, Isaac Newton described gravity as an attractive force between objects of mass. The apple falls because the Earth’s mass is pulling on it (and vice versa). Later, Albert Einstein described in his theory of general relativity that gravity is the result of the curvature of space-time. This curvature also arises under the influence of mass.
Therefore, gravity and mass appear to be inextricably linked. or not? The astrophysicist says that this force can also exist without mass Richard Liu From the University of Alabama in Huntsville in A Scientific publishingThis could also make the existence of dark matter redundant.
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Dark matter
Dark matter is an as-yet-undiscovered substance that appears to make up more than eighty percent of the mass of the universe. This additional dark mass is necessary because the known visible mass does not exert enough gravity to bind galaxies and galaxy clusters together.
Physicists have been searching for dark matter for decades. So far, this research has not been in vain. This makes scientists look for other explanations. Some suggest that Einstein’s laws of gravity are widely flawed and need to be modified.
Liu offers another alternative. He did not throw Einstein’s mathematical equations into the sea, but rather was inspired by them. He proposed a simplified version of it that allows gravitational curvature of space-time without mass. he He says He described his proposal as being “motivated by my frustration with the status quo, namely the idea that dark matter exists despite the absence of any direct evidence.”
Negative mass
Liu’s proposal is based on two concepts: topological defects and negative mass. Negative mass is the opposite of normal positive mass, just as negative and positive charges are opposites of each other. If you push a ball with negative mass, it will move toward you instead of away from you. The existence of negative mass has never been proven, but it appears frequently in physical theories.
Topological defects are small errors that arise mainly during phase changes, for example when a liquid turns into a solid. Phase changes also occurred in the universe, for example shortly after the Big Bang, when atoms emerged from the hot plasma soup that previously filled space.
According to Liu, topological defects in the form of a series of spherical shells could have arisen during phase changes in cluster regions, where galaxies and clusters later form. It may involve a series of concentric shells that grow larger outward, like the circles created when you throw a pebble into a pond.
peeling
Shells consist of a thin inner layer of positive mass and a thin outer layer of negative mass. “The total mass of the two layers — which is all you can measure in terms of mass — is exactly zero,” Liu says. “But when a star falls on this crust, it experiences a strong gravitational force that pulls it towards the center of the crust.” This makes it seem as if there must be additional mass, in the form of dark matter.
Liu admits that his idea is still “very suggestive.” This would not simply disprove the existence of dark matter. It is also not yet clear how his theory can be tested. But he says: “This is the first evidence that gravity can exist without mass.”
