Dark Energy: Mass, Distance & Gravity Relationships

In summary, the conversation discusses the role of mass in determining the distance at which two objects are no longer gravitationally bound and start moving away from each other due to dark energy. The relationship between the forces of gravity and dark energy on mass is also explored through equations. The findings suggest that objects with masses of 1 M_{\odot}, 10^{10} M_{\odot}, and 10^{13} M_{\odot} are all gravitationally bound and will not be disrupted.
  • #1
chris2112
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0
Is there a function of mass that tells us the distance that two objects are no longer gravitationally bound and start moving away from each other due to dark energy? Is mass arbitrary at a certain distance? To make my question broader, can anyone show me equations describing relationships between the forces of gravity and dark energy on mass?
 
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  • #2
Following http://arxiv.org/abs/astro-ph/0302506, we can define the rough length scale at which objects begin to disspiate due to dark energy by:
[tex]-\frac{4\pi}{3}\left(\rho + 3P\right)R^3 \sim M [/tex]

Taking a normal value for [tex]\Lambda[/tex] and assuming an equation of state of -1, such that [tex]\rho = - P[/tex], I get

For a mass of [tex]1 M_{\odot}[/tex] , ~100 pc (Solar system),
For a mass of [tex]10^{10} M_{\odot}[/tex], ~ 200 kPc (Galaxy),
For a mass of [tex]10^{13} M_{\odot}[/tex], ~ 2MPc (Cluster).

This suggests that all three systems are gravitationally bound and will never be disrupted.
 

1. What is dark energy?

Dark energy is a theoretical form of energy that is thought to make up about 70% of the universe. It is believed to be responsible for the accelerating expansion of the universe.

2. How is dark energy related to mass?

Dark energy is not directly related to mass. In fact, dark energy is thought to have a constant density, regardless of the amount of mass in the universe. However, it is believed that dark energy is responsible for counteracting the gravitational pull of mass, causing the expansion of the universe to accelerate.

3. What is the relationship between dark energy and distance?

The relationship between dark energy and distance is complex and not fully understood. However, it is believed that the density of dark energy remains constant as the universe expands, resulting in a stronger force of dark energy between objects that are farther apart.

4. How does dark energy affect gravity?

Dark energy is thought to have a repulsive effect on gravity, causing the expansion of the universe to accelerate. This is because dark energy is believed to counteract the gravitational pull of mass, resulting in a weaker force of gravity between objects.

5. Can dark energy be observed or measured?

Dark energy cannot be observed directly, but its effects can be measured through observations of the expansion of the universe. Scientists use data from supernovae, cosmic microwave background radiation, and galaxy clustering to study the effects of dark energy and try to understand its properties.

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