Difference between particle horizon and cosmological event horizon?

In summary, the Particle Horizon and Cosmological Event Horizon are both limits to what we can see in the universe, but the Particle Horizon is based on the age of the universe and the speed of light, while the Cosmological Event Horizon is determined by the geometry and expansion history of the universe. The Cosmological Event Horizon is also subject to debate and may not be a clear observational limit.
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touqra
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What is the difference between particle horizon and cosmological event horizon?
 
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  • #2
touqra said:
What is the difference between particle horizon and cosmological event horizon?
The Particle Horizon is the limit of what we can see today, (it takes longer than the present age of the universe for light to reach us from beyond the PH), the Event Horizon is the limit of what we may ever see, even if we wait for ever. (the EH is determined by the geometry and expansion history of the universe)

Garth
 
  • #3
Garth said:
the Event Horizon is the limit of what we may ever see, even if we wait for ever. (the EH is determined by the geometry and expansion history of the universe)

Garth

Could you elaborate further on the Cosmological EH?
 
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The horizons thing creates more confusion than clarity, IMO. In our [observable] universe, the surface of last scattering is the observational limit - again IMO. Super-hubble fluctuations may have left trace imprints on the CMB - albeit that is debatable - but in a temporally bounded BB universe, it is impossible to observe entities that [may or may not have] existed prior to recombination.
 

1. What is the difference between particle horizon and cosmological event horizon?

The particle horizon is the maximum distance that particles in the universe could have traveled since the Big Bang, while the cosmological event horizon is the maximum distance from which light could have reached us since the Big Bang.

2. How are particle horizon and cosmological event horizon calculated?

Particle horizon is calculated by taking into account the age of the universe, the speed of light, and the expansion rate of the universe. The cosmological event horizon is calculated by considering the age of the universe and the expansion rate, but also takes into account the curvature of space-time.

3. What is the significance of the particle horizon and cosmological event horizon?

The particle horizon and cosmological event horizon both provide important information about the size and age of the universe. They also help us understand the limits of our observable universe and the expansion of the universe.

4. How do the particle horizon and cosmological event horizon change over time?

The particle horizon and cosmological event horizon both increase as the universe expands, since more distant objects are moving away from us at a faster rate. However, the cosmological event horizon can also shrink if the expansion of the universe accelerates due to dark energy.

5. Can we ever observe objects beyond the particle horizon or cosmological event horizon?

No, we cannot observe objects beyond the particle horizon or cosmological event horizon. This is because the objects are too far away for their light to have reached us, or the expansion of the universe has carried them away from us faster than the speed of light.

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