Exploring Cosmic Clocks with General Relativity

In summary, David L. Wiltshire's work discusses the quantification of cosmic acceleration and dark energy. He presents a new approach to cosmological averaging and resolves the Sandage-de Vaucouleurs paradox. His work has the potential to fundamentally change theoretical and observational cosmology.
  • #1
wolram
Gold Member
Dearly Missed
4,446
558
http://arxiv.org/abs/gr-qc/0702082

Cosmic clocks, cosmic variance and cosmic averages
Authors: David L. Wiltshire
Comments: 72 pages, 5 figures, typos fixed; further summary at this http URL

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. [Abridged]
 
Space news on Phys.org
  • #2
Last edited by a moderator:
  • #3
So i did, can this one be deleted?
 

1. What is General Relativity?

General Relativity is a theory of gravity developed by Albert Einstein in the early 20th century. It describes the way that massive objects, like planets and stars, warp the fabric of space and time, causing other objects to move in a curved path.

2. How does General Relativity relate to Cosmic Clocks?

In General Relativity, the warping of space and time affects the passage of time itself. This means that time runs differently in different parts of the universe, depending on the strength of gravity. Cosmic clocks, such as pulsars and black holes, can be used to measure these time differences and provide insight into the effects of gravity on the universe.

3. What are some examples of Cosmic Clocks?

Some examples of Cosmic Clocks include pulsars, which are rapidly rotating neutron stars that emit regular pulses of radiation, and black hole binaries, which are systems of two black holes orbiting each other and emitting gravitational waves. Other examples include white dwarf binaries and supernovae explosions.

4. How can we use General Relativity to explore Cosmic Clocks?

General Relativity provides a mathematical framework for understanding the behavior of massive objects and their effects on the fabric of space and time. By applying this theory to observations of Cosmic Clocks, we can gain a better understanding of the nature of gravity and the structure of the universe.

5. What are some current research topics in the field of "Exploring Cosmic Clocks with General Relativity"?

There are many ongoing research projects in this field, including studying the stability of pulsar clocks, using Cosmic Clocks to test the predictions of General Relativity, and searching for new types of Cosmic Clocks. Other research topics include using Cosmic Clocks as probes of the early universe and studying the effects of strong gravitational fields on the passage of time.

Similar threads

Replies
3
Views
1K
Replies
2
Views
445
Replies
0
Views
136
  • Cosmology
Replies
4
Views
1K
Replies
37
Views
2K
Replies
13
Views
2K
Replies
1
Views
1K
Replies
20
Views
1K
Back
Top