In 2009, Dutch theoretical physicist Erik Verlinde proposed an alternative theory for gravity known as emergent or induced gravity. According to Verlinde, gravity is not a fundamental force of nature but an entropic force arising from the “information associated with the positions of material bodies.” Unlike Einstein’s theory of gravity, Verlinde’s theory eliminates the need for dark matter, an undetectable matter said to make up 95% of the universe.
In 2016, Dutch astronomers, led by Margot Brouwer from Leiden Observatory, tested Verlinde’s theory by employing the gravitational lensing effect. This phenomenon occurs when massive celestial bodies, like galaxy clusters, bend light due to a curvature in space-time. Brouwer’s team found that Verlinde’s “[agreed] well” with the lensing effects of over 33,000 galaxies her team observed and didn’t need to rely on the existence of dark matter. But, it was also noted that Einstein’s theory of gravity, combined with the existence of dark matter, could also explain these effects.
But, another study by Princeton in 2017 showed less-than-poetical results for Verlinde’s theory of emergent gravity. Princeton graduate student Kris Pardo—now assistant professor of physics and astronomy at the University of Southern California—assembled a sample of 81 isolated dwarf galaxies and measured their rotational velocities. Dwarf galaxies appear to have extremely high concentrations of dark matter, providing a unique opportunity to compare theories. While emergent gravity was able to predict the rotation velocity of the smaller galaxies, its predicted velocities for the more massive galaxies were far too low. But, this difference in predicted and experimental velocities could possibly be due to the galaxies being shaped differently compared to how they appear. Pardo and his colleagues are hoping to secure time on the Very Large Array telescopes in New Mexico to make better measurements.
These are two of the earlier studies done on Verlinde’s theory of gravity. There are many more that test the theory using the Cosmic Microwave Background (CMB), mass predictions, and theoretical mathematical functions. It’s important to note that Verlinde’s theory is still a work in progress, and the scientific community is actively exploring and testing its implications. Further experimental verification is needed to confirm or refute its validity.
Sources:
- https://bigthink.com/hard-science/physicist-radical-theory-of-gravity/#:~:text=The%20Dutch%20physicist%20Erik%20Verlinde%27s,resorting%20to%20%22dark%20matter%22.
- https://bigthink.com/hard-science/controversial-new-theory-that-says-theres-no-gravity-or-dark-matter-actually-passes-its-first-test/
- https://www.quantamagazine.org/researchers-check-space-time-to-see-if-its-made-of-quantum-bits-20170621/
