Enjoying EarthSky? Subscribe.

250,866 subscribers and counting ...

1st test of new theory of gravity

Eric Verlinde’s new theory of gravity – an alternative to Einstein’s theory – eliminates the need for dark matter. To test it, astronomers measured gravity around 33,000 galaxies.

A team led by astronomer Margot Brouwer of Leiden Observatory in The Netherlands has tested the new theory of gravity by theoretical physicist Erik Verlinde (University of Amsterdam) for the first time. Brouwer and her team examined the lensing effect of gravity around more than 33,000 galaxies to put predictions of Verlinde’s theory to the test. The team’s conclusion was that Verlinde’s theory “agrees well” with the observations. The results were published December 12, 2016 in the British journal Monthly Notices of the Royal Astronomical Society.

Verlinde’s theory is an alternative to Einstein’s theory of gravity (general relativity). Brouwer’s announcement of these first observational tests come just as scientist are discussing the first evidence that Einstein’s theory breaks down at the edges of black holes.

The new theory eliminates the need for dark matter in our universe. In recent decades, astronomers have relied on the concept of dark matter to explain an unseen mass in which our galaxy and others appear to be immersed. Einstein’s existing theory works entirely only if these invisible and undiscovered particles of dark matter exist. Verlinde’s new theory, on the other hand, doesn’t rely on dark matter to work. It predicts how much gravity there must be, based only on the mass of the visible matter.

That’s why – in order to test Verlinde’s theory – Brouwer calculated his theory’s prediction for the gravity of 33,613 galaxies, based only on their visible mass. Her statement explained:

She compared this prediction to the distribution of gravity measured by gravitational lensing, in order to test Verlinde’s theory. Her conclusion is that his prediction agrees well with the observed gravity distribution, but she emphasizes that dark matter could also explain the extra gravitational force.

Gravitational lensing works - as Albert Einstein explained in his theory of general relativity – mass bends light. The gravitational field of a distant galaxy or galaxy cluster causes light to bend around it. From Earth, we see the light as displaced from where it would otherwise be. Image via SpaceTelescope.org.

Gravitational lensing works because – as Albert Einstein explained in his theory of general relativity – mass bends light. The gravitational field of a distant galaxy or galaxy cluster causes light to bend around it. From Earth, we see the light as displaced from where it would otherwise be. Image via NASA/ ESA/ L. Calçada/ SpaceTelescope.org.

Brouwer’s statement went on to say that Verlinde’s new theory is currently only applicable to:

… isolated, spherical and static systems.

In other words, in formulating his theory, Verlinde relied on the simplest possible cases, and, of course, these sorts of systems don’t describe our actual universe, which is, instead, dynamic and complex. Whats more, these scientists acknowledge that many observations cannot yet be explained by the new theory, and so, they say:

…so dark matter is still in the race.

Brouwer commented:

The question now is how the theory develops, and how it can be further tested. But the result of this first test definitely looks interesting.

Read more and see a video about Erik Verlinde’s new gravity theory

The gravity of galaxies bends space, such that the light traveling through this space is bent. This bending of light allows astronomers to measure the distribution of gravity around galaxies, even up to distances a hundred times larger than the galaxy itself. (c) APS/Alan Stonebraker; galaxy images from STScI/AURA, NASA, ESA, and the Hubble Heritage Team / astronomie.nl.

The gravitational bending of light lets astronomers measure what they call the “distribution” of gravity around galaxies, even up to distances 100 times larger than the galaxy itself. Image copyright American Physical Society/ Alan Stonebraker; galaxy images from STScI/AURA, NASA, ESA, and the Hubble Heritage Team / astronomie.nl.

Bottom line: Astronomer Margot Brouwer of Leiden Observatory in The Netherlands has conducted the first observational test of Erik Verlinde’s new theory of gravity. She said the observations agree with Verlinde’s theory, but that Einstein’s theory – with the necessary addition of dark matter – can also explain them.

Via astronomie.nl

Deborah Byrd

MORE ARTICLES