The Universe Doesn’t Need Dark Energy To Expand Faster, Says New Theory

Mathematicians argue in a new paper that the accelerating expansion of the universe can be explained without dark energy.


“Dark energy” is a mysterious force that is predicted to take up more than 68% of our universe. Since observations in 1990s that the expansion of the universe is accelerating, dark energy has been the leading hypothesis to explain why. Now three mathematicians claim they can show why the expansion is speeding up without the need to invoke dark energy, which they call "a fudge factor".

The idea of dark energy is linked to Einstein’s Theory of General Relativity. Believing in 1917 that the universe was static and looking to address the issue of “vacuum energy”, Einstein added a cosmological constant to represent an anti-gravitational force. When the fact of universe’s expansion was confirmed, Einstein shelved the constant, calling it his greatest mistake. 

But in order to explain why the expansion is speeding up, the idea of the cosmological constant came back into fashion as being interchangeable with dark energy - a fact that did not sit well with Blake Temple and Zeke Vogler from the UC Davis and Joel Smoller from the University of Michigan, Ann Arbor. In their new paper they argue that invoking dark energy is not necessary since Einstein’s equations in the original theory of General Relativity are correct. What needs adjusting is the idea that the universe expands in a uniform way.

“We set out to find the best explanation we could come up with for the anomalous acceleration of the galaxies within Einstein’s original theory without dark energy,” said Temple. 

The mathematicians explain that cosmological models based on Friedmann equations, which govern the expansion of space in the universe, assume that matter is expanding evenly throughout. But the equations actually show this kind of space-time model is unstable, propose the scientists. Any disturbance will put it into acceleration. 

 The scientists says that the universe as a whole cannot be measured as one static entity, as its inherent instability prevents that. Instead, you can measure local space-times created by the instability. These would have the same cosmic accelerations as in the theories of dark energy, maintain the mathematicians. 

“The math isn’t controversial, the instability isn’t controversial,” Temple said. “What we don’t know is, does our Milky Way galaxy lie near the center of a large under-density of matter in the universe.” 

Their paper also includes predictions that can be tested to separate their model from dark energy models.

You can read the paper in the Proceedings of the Royal Society A.

Want to know more about dark energy? Check out this video:

 

 

Trying to spot China’s green energy tipping point

Pay attention to the decisions made by the provinces.

Surprising Science
  • China leads the world in numerous green energy categories.
  • CO2 emissions in the country totaling more than all coal emissions in the U.S. have recently emerged.
  • This seems to be an administrative-induced blip on the way towards a green energy tipping point.
Keep reading Show less

Got a question for a real NASA astronomer? Ask it here!

NASA astronomer Michelle Thaller is coming back to Big Think to answer YOUR questions! Here's all you need to know to submit your science-related inquiries.

Surprising Science

Big Think's amazing audience has responded so well to our videos from NASA astronomer and Assistant Director for Science Communication Michelle Thaller that we couldn't wait to bring her back for more!

And this time, she's ready to tackle any questions you're willing to throw at her, like, "How big is the Universe?", "Am I really made of stars?" or, "How long until Elon Musk starts a colony on Mars?"

All you have to do is submit your questions to the form below, and we'll use them for an upcoming Q+A session with Michelle. You know what to do, Big Thinkers!

Keep reading Show less

Elon Musk says Boring Company tunnel opens Dec. 10

The Boring Company plans to offer free rides in its prototype tunnel in Hawthorne, California in December.

Image: Claudia Soraya
Technology & Innovation
  • The prototype tunnel is about 2 miles long and contains electric skates that travel at top speeds of around 150 mph.
  • This is the first tunnel from the company that will be open to the public.
  • If successful, the prototype could help the company receive regulatory approval for much bigger projects in L.A. and beyond.
Keep reading Show less

Take the Big Think survey for a chance to win :)

Calling all big thinkers!

  • Tell us a little bit about where you find Big Think's videos, articles, and podcasts.
  • Be entered for a chance to win 1 of 3 Amazon gift cards each worth $100.
  • All survey information is anonymous and will be used only for this survey.
Keep reading Show less

Tesla introduces new Model 3 at $45,000

The new version's battery has a shorter range and a price $4,000 lower than the previous starting price.

Tesla Model 3 (Photo: Tesla)
Technology & Innovation
  • Tesla's new version of the Model 3 costs $45,000 and can travel 260 miles on one charge.
  • The Model 3 is the best-selling luxury car in the U.S.
  • Tesla still has yet to introduce a fully self-driving car, even though it once offered the capability as an option to be installed at a future date.
Keep reading Show less

Cancer researcher says keto is not a fad diet

Anatomy and physiology professor David Harper claims a recent study in The Lancet is flawed.

Photo: Shutterstock
Surprising Science
  • The low-carbohydrate group in a recent Lancet study were typically middle-aged, obese, sedentary, diabetic smokers.
  • The study was not a randomized, controlled, double-blind experiment.
  • Harper has been in ketosis for six years, and says it has profound effects on cancer patients, among other chronic ailments.
Keep reading Show less

Are you a Boltzmann Brain? Why nothing in the Universe may be real

A mind-bending paradox questions the nature of reality.

Pixabay
Surprising Science
  • Boltzmann Brains are hypothetical disembodied entities with self-awareness.
  • It may be more likely for a Boltzmann Brain to come into existence than the whole Universe.
  • The idea highlights a paradox in thermodynamics.
Keep reading Show less
Mind & Brain
  • When it comes to educating, says Dr. Elizabeth Alexander, a brave failure is preferable to timid success.
  • Fostering an environment where one isn't afraid to fail is tantamount to learning.
  • Human beings are complicated and flawed. Working with those complications and flaws leads to true knowledge.
Keep reading Show less