Wiltshire casts doubt on existence of dark energy

In summary, Wiltshire argues that the speculation of a "dark energy particle" is unnecessary in explaining the appearance of cosmic acceleration. He suggests that gravitational energy differences between bound systems and the expanding universe can account for this phenomenon. He also proposes a new approach to cosmological averaging which solves the Sandage-de Vaucouleurs paradox and offers a new model of the universe with various testable consequences. Wiltshire's argument is that the equivalence principle does not allow for the localization of gravitational energy, which can significantly affect the parameters of any effective homogeneous isotropic model.
  • #1
marcus
Science Advisor
Gold Member
Dearly Missed
24,775
792
Wiltshire casts doubt on existence of "dark energy"

Wiltshire is a minority voice in cosmology, but one worth listening to. Speculation about a "dark energy particle" would be in vain if the appearance of acceleration can be traced to classic GR effects, which is what he tries to do. Wiltshire suggests that a positive cosmological constant is NOT NEEDED to explain observation, nor is any sort of dark energy or quintessence.
This bears on the discussion of various approaches to quantum gravity, which have differing compatibility with the cosmological constant
http://www2.phys.canterbury.ac.nz/~dlw24/universe/

http://arxiv.org/abs/gr-qc/0702082
Cosmic clocks, cosmic variance and cosmic averages
David L. Wiltshire
72 pages, 5 figures

"Cosmic acceleration is explained quantitatively, purely in general relativity, as an apparent effect due to quasilocal gravitational energy differences that arise in the decoupling of bound systems from the global expansion of the universe. 'Dark energy' is recognised as a misidentification of those aspects of gravitational energy which by virtue of the equivalence principle cannot be localised, namely gradients in the energy associated with the expansion of space and spatial curvature variations in an inhomogeneous universe, as we observe. Gravitational energy differences between observers in bound systems, such as galaxies, and volume-averaged comoving locations within voids in freely expanding space can be so large that the time dilation between the two significantly affects the parameters of any effective homogeneous isotropic model one fits to the universe. A new approach to cosmological averaging is presented, which implicitly solves the Sandage-de Vaucouleurs paradox. When combined with a nonlinear scheme for cosmological evolution with back-reaction via the Buchert equations, a new observationally viable quantitative model of the universe is obtained. The expansion age is increased, allowing more time for structure formation. The baryon density fraction obtained from primordial nucleosynthesis bounds can be significantly larger, yet consistent with primordial lithium abundance measurements. The angular scale of the first Doppler peak in the CMB anisotropy spectrum fits the new model despite an average negative spatial curvature at late epochs, resolving the anomaly associated with ellipticity in the CMB anisotropies. A number of other testable consequences are discussed, with the potential to profoundly change the whole of theoretical and observational cosmology."
 
Last edited:
Physics news on Phys.org
  • #2
Does the equivalance principle insist gravitational energy cannot be localized? I don't really follow that part of the argument. Gravity appears localized on the scale of our solar system, and probably the Milky Way. I am suspicious of effects that are not locally evident.
 
  • #3


it is important to consider all perspectives and evidence when examining a scientific concept. Wiltshire's work raises important questions about the existence of dark energy and the need for a cosmological constant in explaining the acceleration of the universe. While his ideas may be controversial, they should not be dismissed without further investigation and analysis. It is important for the scientific community to continue to explore different theories and approaches in order to gain a better understanding of the universe. Wiltshire's work provides a valuable contribution to the ongoing discussion about dark energy and its role in cosmology.
 

1. What is dark energy?

Dark energy is a theoretical form of energy that is believed to make up approximately 70% of the universe. It is thought to be responsible for the accelerating expansion of the universe and its exact nature is still not fully understood.

2. How did the Wiltshire study cast doubt on the existence of dark energy?

The Wiltshire study proposed an alternative theory of gravity that could explain the observed cosmic acceleration without the need for dark energy. This theory, called the "timescape cosmology", suggests that the universe is not expanding but is instead in a state of eternal expansion and contraction.

3. What evidence supports the existence of dark energy?

The observation of distant supernovae and the cosmic microwave background radiation are two key pieces of evidence for the existence of dark energy. These observations show that the expansion of the universe is accelerating, which is not accounted for by traditional theories of gravity.

4. What are the implications of the Wiltshire study for our understanding of the universe?

If the Wiltshire study's theory of timescape cosmology is proven to be correct, it would fundamentally change our understanding of the universe and the role of dark energy. It would also call into question the validity of other theories and models that rely on the existence of dark energy.

5. What further research is needed to confirm or refute the Wiltshire study's findings?

Further observational and theoretical studies are needed to fully understand the implications of the Wiltshire study and to confirm or refute its findings. This could involve more precise measurements of the cosmic acceleration, as well as testing the predictions of the timescape cosmology through other observations and experiments.

Similar threads

Replies
8
Views
1K
  • Beyond the Standard Models
Replies
3
Views
2K
  • Beyond the Standard Models
Replies
2
Views
310
Replies
7
Views
2K
Replies
2
Views
446
Replies
2
Views
1K
Replies
1
Views
1K
Replies
37
Views
2K
Replies
19
Views
671
Back
Top