Thought experiment: Communication beyond the particle horizon

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SUMMARY

This discussion explores the concept of communication beyond the particle horizon using a network of nodes that broadcast signals at light speed. The white nodes represent primary stations, while the pink nodes serve as intermediary stations that relay signals. Despite the limitations imposed by the expansion of the universe, it is established that signals can be exchanged between the starting and ending nodes through the pink nodes, as long as they remain within each other's cosmological horizons. The growth of particle horizons over time allows for potential communication in a finite timeframe, as illustrated by the Davis expansion graphs.

PREREQUISITES
  • Understanding of particle horizons in cosmology
  • Familiarity with the concept of light speed communication
  • Knowledge of the Hubble radius and its implications
  • Basic grasp of cosmological expansion and its effects on signal transmission
NEXT STEPS
  • Study the Davis expansion graphs for a deeper understanding of particle horizon growth
  • Research the implications of the Hubble radius on communication between distant nodes
  • Explore the concept of cosmological horizons and their role in signal transmission
  • Investigate advanced theories on communication in an expanding universe
USEFUL FOR

Astronomers, theoretical physicists, and anyone interested in the implications of cosmological expansion on communication methods in the universe.

Lanniakea
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Refer to this image: http://imgur.com/xT20HOv

  1. The white nodes are 'stations' which broadcast signals at light speed. The blue circles around them represent the particle horizon relative to these nodes.
  2. The pink nodes are intermediary stations in between these stations that pass on the signal. The pink circles are their respective particle horizons.
  3. All nodes always maintain the same distance relative to each other; they move in a way to negate the expansion of the universe.
  4. The number of nodes in the example is arbitrary.
The idea:

A signal is sent from the starting node and reaches the first pink node. From here it is sent toward the next white 'station' node. Now here's the idea: Even though the signal has left the particle horizon of the starting node, the next station's particle horizon includes both white nodes. So while the two white nodes cannot communicate directly, the pink node is in reach for both of them.

The Question: Could the starting and ending node exchange information in a finite amount of time, given that the nodes maintain their relative distances?

Thanks!
 
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Lanniakea said:
The Question: Could the starting and ending node exchange information in a finite amount of time, given that the nodes maintain their relative distances?
Yes. Particle horizons grow without limit as time goes on. See the Davis expansion graphs: https://www.physicsforums.com/attachments/davisdiagramoriginal2-jpg.55869/

But take note that if your circles are of particle horizon sizes, they are much larger than the Hubble radius and they cannot "hold station", but will instead be receding from each other at a rate exceeding c. Also, they must be within each others cosmological (communications) horizons to ever communicate.
 
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