Inflation & the Hubble Length in cm

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Discussion Overview

The discussion revolves around the concept of Hubble length in the context of cosmological inflation. Participants seek to understand the Hubble length and its representation in centimeters, while also referencing its relation to Hubble time and the use of online calculators for conversions.

Discussion Character

  • Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • Some participants mention that the Hubble time is approximately 14 billion years, suggesting that the Hubble length is about 14 billion lightyears, with a preference for the more precise figure of 13.8 billion years.
  • One participant defines Hubble time as 1/H0 and Hubble length as c/H0, indicating a relationship between these concepts.
  • Another participant suggests using Google calculator for calculating Hubble length, providing a step-by-step method to obtain the value in meters.
  • Some participants express skepticism about the practicality of expressing Hubble length in centimeters, noting that it is a very large distance.
  • There is mention of Google calculator's capability to perform automatic unit conversions, which could simplify the process of obtaining Hubble length in different units.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the practicality of expressing Hubble length in centimeters, with some suggesting it is unnecessary due to the large scale involved. There are multiple viewpoints on how to calculate and represent Hubble length.

Contextual Notes

The discussion includes assumptions about the definitions of Hubble time and length, as well as the accuracy of the values used. There are unresolved steps in the calculations presented, particularly regarding the conversion process and the implications of using different units.

Who May Find This Useful

This discussion may be useful for individuals interested in cosmology, particularly those exploring concepts related to the expansion of the universe and the calculations involved in determining cosmological distances.

Golfer
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I am presently reading a paper on Inflation. It uses the term Hubble length. Can someone provide the Hubble length in cm.
 
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Golfer said:
I am presently reading a paper on Inflation. It uses the term Hubble length. Can someone provide the Hubble length in cm.

The Hubble time is about 14 billion years. That means the Hubble length is about 14 billion lightyears. 13.8 might be better.

definitions: the hub time is 1/H0
the hub length is c/H0

just use google calculator. type this into the google search window verbatim
71 km/s/megaparsec
and press "search"

you will get an inverse time in Hertz

now type c divided by that, verbatim, in other words
c/(71 km/s/megaparsec)
and say search again

you will get 1.3 x 1026 meters

that is the Hubble length in meters
google calculator will just calculate it for you automatically and tell you that
 
Last edited:
Can someone provide the Hubble length in cm.
marcus said:
about 14 billion lightyears.
Thus, it is probably silly to describe it in centimeters.
 
Google calculator also does automatic unit conversion, you can say things like

c/(71 km/s/megaparsec) in centimeters

It is a great tool.
 

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