From Katia Moskvitch at Quanta:
The neutron-star collision was just the beginning. New data in the months since that discovery have made life increasingly difficult for the proponents of many of the modified-gravity theories that remain. Astronomers have analyzed extreme astronomical systems that contain spinning neutron stars, or pulsars, to look for discrepancies between their motion and the predictions of general relativity — discrepancies that some theories of alternative gravity anticipate. These pulsar systems let astronomers probe gravity on a new scale and with new precision. And with each new observation, these alternative theories of gravity are having an increasingly hard time solving the problems they were invented for. Researchers “have to sweat some more trying to get new physics,” said Anne Archibald, an astrophysicist at the University of Amsterdam.
All attempts to directly detect dark matter and dark energy have failed, however. That fact “kind of leaves a bad taste in some people’s mouths, almost like the fictional planet Vulcan,” said Leo Stein, a theoretical physicist at the California Institute of Technology. “Maybe we’re going about it all wrong?” More.
But at least they recognize and admit it. There is no shame in being wrong. Admitting it puts us on the road to being right.
“The business of alternative gravity theories is a messy one,” Archibald said. Some would-be replacements for general relativity, like string theory and loop quantum gravity, don’t offer testable predictions. Others “make predictions that are spectacularly wrong, so the theorists have to devise some kind of a screening mechanism to hide the wrong prediction on scales we can actually test,” she said. More.
See also: Proposed dark matter solution: “Gravity is not a fundamental governance of our universe, but instead a reaction to the makeup of a given environment.” Dark matter could be the answer to a number of cosmology questions but it could also be the phlogiston or ether of today’s science – substances that were assumed to exist because their existence would solve a problem but th problem was not properly understood. When it was, no one needed those substances to exist. Time will tell, we hope.
Supernova analysis questions dark energy cosmic acceleration
Take back Nobel prizes for accelerating expansion of universe? Dark energy might be an illusion say some researchers. But we thought only a denialist was allowed to doubt the accelerating expansion of the universe. Rules change?
Post-modern physics: String theory gets over the need for evidence