The Dark Energy Survey (DES), an international astronomy project studying the accelerating expansion of the universe, has released its final results after 7 years of observations. The findings provide new insights into dark energy, the mysterious force driving the universe’s expansion, suggesting it may be more dynamic over time than previously believed.
Landmark Study Challenges ‘Cosmological Constant’ Theory of Dark Energy
The DES analyzed light from over 1,500 supernovae – stellar explosions that can be used to measure cosmic distances – along with data on millions of galaxies and patterns of subtle distortions in the cosmic microwave background radiation. This allowed researchers to create the largest and most precise 3D map of the distribution of matter in the universe, spanning over 5 billion light years (Fnal.gov).
The findings present a challenge to the long-held ‘cosmological constant’ theory, which posits that dark energy is uniform and unchanging over space and time. Instead, they show dark energy may be weakening as the universe expands (SingularityHub). This indicates it could have varied substantially earlier in cosmic history, upending current models.
| Key DES Findings | Implications |
|---|---|
| Dark energy density decreased by 10% from 9 billion years ago to today | Points to dynamic dark energy instead of cosmological constant |
| Expansion rate 7% higher than predicted by Planck satellite CMB data | Standard cosmology model may need revision |
| No evidence universe will tear itself apart over time | ‘Big Rip’ future scenario less likely |
“It’s incredibly exciting that after ten years of observing and analyzing, we have a result that challenges the standard model of cosmology” said lead researcher Prof. Claire Burke of Swinburne University (BNNBreaking). “Now we have to redraw our model of the contents of the universe, and our picture of its future.”
New Insights Point to Possible Fate of the Universe
The DES results support dark energy having the characteristics of a cosmological constant in the early universe which has weakened slightly over billions of years. This modest evolution means a ‘Big Rip’ scenario where cosmic expansion eventually tears galaxies and atoms apart is improbable.
“The data favors a model where dark energy is real and consistent with Einstein’s cosmological constant, but it grows more diluted as the universe expands,” explained DES spokesperson Prof. Rachel Bean of Cornell University (IFLScience). “This is indicative of new physics beyond the standard model relating to dark energy.”
Researchers say more sensitive experiments will be needed to shed further light on dark energy’s properties and role in cosmic evolution. Upcoming surveys like NASA’s Nancy Grace Roman Space Telescope, scheduled to launch in 2025, will observe millions more supernovae to map expansion over the last 12 billion years (Astronomy.com). On an even larger scale, the European Space Agency’s Euclid satellite will precisely measure 10 billion galaxy shapes and redshifts.
“Dark energy is still a mysterious entity, but the DES results indicate it may not be as immutable as once thought,” summarized Bean. “This opens up exciting possibilities as we probe deeper into the history of our ever-changing universe.”
What is Dark Energy?
Dark energy is the name given to the unknown force behind the accelerating expansion of the universe first discovered in 1998. It makes up 68% of all matter and energy in the cosmos.
The leading theory is that dark energy represents the intrinsic energy stored in the vacuum of empty space across the universe. This manifests as an inherent pressure causing space to expand at an accelerating rate.
The discovery of dynamic dark energy adds a new wrinkle – indicating properties like density can evolve over the eons as space stretches. This hints at new physics beyond Einstein’s general relativity and the standard model of particle physics.
Most experts think this ‘new physics’ points to exotic substances like scalar fields that fill space homogeneously or extensions of general relativity incorporating aspects of quantum mechanics. Further observations should help narrow down the possibilities.
The Dark Energy Survey in Summary
The Dark Energy Survey was an international collaboration between over 400 scientists at 26 institutions in 7 countries including the United States, Spain, the UK, Brazil, and Germany. It operated between 2013-2019.
The survey team built and operated a super-sensitive 570-megapixel digital camera called DECam, mounted on the Victor M. Blanco 4-meter Telescope in Chile. This instrument was able to image galaxies and supernovae out to distances of 8 billion light years.
In total the survey captured data on:
- 1,814 Type Ia supernovae
- 300 million galaxies
- Thousands of galaxy clusters
This enabled creating the most detailed 3D maps of the cosmos ever made spanning 5 billion light years. These high-precision observations provided multiple independent ways to measure and study the effects of dark energy.
Now that observations are complete, the focus turns to further analysis and modeling to extract the survey’s full implications. Along with other experiments, the results promise to usher in a new era of cosmology rewriting our understanding of the universe’s origins, expansion history, and ultimate fate.
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