Particle horizon in Lemaître model

In summary, the particle horizon is the boundary between observable and unobservable parts of the universe. It can be calculated using the time-dependent scale factor function and observational parameters. The furthest known object currently has a redshift factor of z=8.2, equivalent to a proper distance of 30 billion light years. However, based on calculations from the integral, the particle horizon is estimated to be around 46 billion light years.
  • #1
EhsanZ
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What is the exact calculation of Particle horizon in Lemaître model? Does it exist? Is it finite or infinite?
Can anyone calculate that integral?
Thanks
 
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  • #2
EhsanZ said:
What is the exact calculation of Particle horizon in Lemaître model? Does it exist? Is it finite or infinite?
Can anyone calculate that integral?
Thanks

The particle horizon marks the boundary between observable and un-observable parts of the universe, and yes, this integral can be calculated using the time-dependent scale factor function taken from the FLRW metric, as well as observational parameters. So far as I could find ( these things change pretty regularly ) the furthest know object to date has a redshift factor of z=8.2 which would be equivalent to a proper distance ( remember, this is not the same as light-travel distance due to the dynamic expansion of spacetime ) of about 30 billion light years. Reference :

http://en.wikipedia.org/wiki/Observable_universe

If you do the maths from the integral you arrive at a figure of about 46 billion light years.
 
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1. What is the Particle Horizon in the Lemaître model?

The Particle Horizon in the Lemaître model is a theoretical concept in cosmology that represents the maximum distance from which light could have reached us since the beginning of the universe. In other words, it is the boundary of the observable universe.

2. How is the Particle Horizon calculated in the Lemaître model?

The Particle Horizon is calculated by using the comoving coordinates, which take into account the expansion of the universe. It is determined by integrating the speed of light over the age of the universe.

3. What does the Particle Horizon tell us about the universe?

The Particle Horizon tells us about the size and age of the observable universe. It also provides insights into the expansion rate of the universe and the distribution of matter and energy within it.

4. What is the significance of the Particle Horizon in the Lemaître model?

The Particle Horizon is significant because it helps us understand the limits of our observable universe and the effects of the expansion of the universe on the propagation of light. It also plays a crucial role in studying the formation and evolution of large-scale structures in the universe.

5. How does the Particle Horizon differ from the Hubble Sphere?

The Particle Horizon is a theoretical boundary that represents the maximum distance from which light could have reached us since the beginning of the universe. On the other hand, the Hubble Sphere is the distance at which objects are receding from us at the speed of light due to the expansion of the universe. The Particle Horizon takes into account the age of the universe, while the Hubble Sphere does not.

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