It can be easy to take hyped-up science papers as fact, especially when they involve the most esoteric imaginable ideas. But scientists are taking issue with a hyped-up new paper that claims it can eliminate the need for dark matter or dark energy in our Universe.
Observations of our Universe imply that something like 95 percent of it is comprised of mysterious stuff. The math says it could be explained by an invisible mass called dark matter, and energy causing the Universeâs expansion to speed up called dark energy. Here on Earth, no one has directly detected what dark matter and dark energy are made of, which is causing some worry. That includes a new, widely-shared paper proposing an alternative idea. The paper says that one of the problems that is solved by the presence of dark matter and dark energyâthe difference between how a galaxy should rotate according to the laws of physics and how galaxies rotate according to our observationsâcould instead be solved by tweaking the mathematics scientists have developed to explain the behavior of space and time. Lots of scientists think that this flawed idea didnât deserve the hype.
The paperâs hype probably stems from how the internet disseminates science news. The hubbub began with an uncritical press release from the University of Geneva about research from their scientist AndrĂ© Maeder. Perhaps, Maeder proposes, one of the core tenets of Albert Einsteinâs theory of general relativity are wrong under certain conditionsâin large voids where there isnât any mass. Maybe, he proposes, reconsidering the mathematics governing the very fabric of the shape of space will eliminate the need for dark matter and dark energy.
Eliminating the most important topics in physics with some math sounds incredible, so a few news outlets, most notably Newsweek as well as the usual suspects like the Daily Mail and IFLScience, ran with the story without calling outside sources.
If they had, theyâd probably have found out that many physicists donât think Maederâs idea holds water. Several, including Stanford dark energy physicist Andrei Linde and Yale dark matter physicist Priyamvada Natarajan, told Gizmodo that it wasnât worth writing about (despite the fact that it ended up in the fairly prestigious Astrophysical Journal).Â
Most notably, science blogger and theoretical physicist Sabine Hossenfelder picked apart the paper on her blog, Backreactions. âFor those of you who merely want to know whether you should pay attention to this new variant of modified gravity, the answer is no,â she wrote. âThe author does not have a consistent theory. The math is wrong.â
AnĆŸe Slosar at Brookhaven National Lab confirmed Hossenfelderâs report. In its simplest form, he told Gizmodo, âThe main thing that gives it away is that the paper doesnât contain a âLagrangian.â A Lagrangian is like a basic mathematical object that defines a theory. We simply donât know how to do theoretical physics without having a Lagrangian.â He also said that the idea doesnât make testable predictions, something that many physicists treat as a requirement. More about that here.
https://gizmodo.com/thirty-three-famous-physicists-sign-angry-letter-about-1795101181
Natarajan and physicist Jonathan McDowell from the Harvard-Smithsonian Center for Astrophysics both point out that Maeder doesnât fully explain away some of the other astronomical observations bolstering dark matter, like dark matter in galaxy clusters bending the path of light rays:
Don't see how that explains the Bullet Cluster though
— Jonathan McDowell (@planet4589) November 22, 2017
For what itâs worth, Maeder agreed that his âequations are underdetermined,â in an email to Gizmodo responding to Hossenfelderâs post. He pointed out that he felt his interpretation of some cosmologyâs core tenets revealed interesting new results.
Re-formulating the mathematics Einsteinâs theory of general relativity isnât such a new thingâlots of scientists have considered that maybe we observe dark matter and/or dark energy because something is missing, somewhere. Except no matter what happens, experimental evidence continues to confirm that Einsteinâs theory of general relativity is consistent, regardless of what scientists throw at it.
Also, do you have any idea how hard weâve been trying to break general relativity? That thing is unkillable! It passes EVERY test!
— Katie Mack (@AstroKatie) November 22, 2017
Why did the under-developed theory get so much press? The paper, alongside its flashy headline, was promoted to a large audience via the Phys.org press release aggregator (which does sometimes write original stories). Content mills picked it up without checking whether or not it was worth writing aboutâor wrote it regardless.
And also why it's not always a good idea to widely disseminate a press release đ
— Davide Castelvecchi (@dcastelvecchi) November 26, 2017
Itâs important to challenge the scientific status quo, of course. However, scientific advancement requires evidence, robust mathematical theories, and a cohesiveness that scientists do not think Maederâs theory offers.
So, for now, dark matter and dark energy are both alive and well. Which is to say, we donât know what they areâbut theyâre still mysteries physicists are working to solve.
