Dark Energy & the Law of Thermodynamics

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SUMMARY

The forum discussion centers on the relationship between dark energy and the expansion of the universe, specifically addressing whether galaxies are moving apart due to a force overcoming gravity or simply because space is expanding. Participants clarify that galaxies are not accelerating due to an external force but rather because of the inherent properties of space-time and dark energy, which is theorized to exert negative pressure. This negative pressure contributes to the acceleration of the universe's expansion without violating the first law of thermodynamics, as energy conservation must be considered locally rather than globally.

PREREQUISITES
  • Understanding of general relativity and its implications on space-time.
  • Familiarity with dark energy and its role in cosmic expansion.
  • Knowledge of gravitational potential energy and kinetic energy interactions.
  • Basic concepts of cosmological redshift and its distinction from the Doppler effect.
NEXT STEPS
  • Research the properties and implications of dark energy in cosmology.
  • Study Einstein's field equations and their role in describing the curvature of space-time.
  • Learn about the differences between cosmological redshift and Doppler redshift.
  • Explore the concept of negative pressure in the context of dark energy and its effects on cosmic expansion.
USEFUL FOR

Astronomers, physicists, cosmologists, and anyone interested in understanding the dynamics of the universe and the role of dark energy in cosmic expansion.

  • #31
I know spacetime is something but I am wondering what that something is. is it only the gravitational field? is the geometry of spacetime, gravity?
 
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  • #32
Freeman Dyson said:
I know spacetime is something but I am wondering what that something is. is it only the gravitational field? is the geometry of spacetime, gravity?
Our understanding is just that gravity is a word we use to describe the curvature of space-time, and especially how matter affects and reacts to that curvature.
 

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