The document discusses the Space Case Equation, which attempts to answer three questions: 1) How many planets with communicative life have ever existed in a galaxy, 2) How many are likely to exist at any given time, and 3) The average distance between two active communicative civilizations. It provides the variables and values to estimate there are 92 communicative civilizations in the Milky Way galaxy, with an average distance of 85.2 billion cubic light years, or approximately 4,400 light years, between each.

1. The Space Cases

2. The # of planets with interstellarly communicative life
forms in the Milky Way galaxy
The original formula was:
N = R*fpnef lfifcL

3. Well, one, it is answering a slightly different question. Or
rather, slightly different questions. The Drake Equation attempts to
answer the question “How many planets with interstellarly
communicative life forms are there in the Milky Way galaxy today?”
The Space Case Equation attempts to answer three questions:
1. How many planets with interstellarly communicative life forms
(“Drake planets”) have ever existed in a galaxy, based upon the
galaxy’s parameters
2. Based upon the galaxy’s age and the mean # of years a Drake planet is
active, how many are likely to exist at any given point in the galaxy’s
history? (Including the present)
3. What is the mean distance between two active Drake planets?
(Measured in light years)

4.  = # of stars present in galaxy
 = % of stars with planets
 = % of planets in the
habitable zone
 = % of habitable planets
with life
 = % of habitable planets
with life that have developed
interstellar communications
 a = age of the galaxy
 L = mean # of years
communicative civilizations
remain active
 * “Drake planet” refers to a
planet that possesses a race
and/or races of interstellarly
communicative life forms

5. Or, once the latter part of the equation has been
determined:

6. In the highly improbable event the planets with
interstellarly communicative life forms were uniformly
dispersed across the galaxy, how many light years
would it take for a light signal sent by one to reach the
other?*
*This equation does not attempt to factor in the usage
of wormholes

7.  Why ?
This is the formula for determining the volume of a
cylinder. Such as…

8. So why ? Why is the galaxy’s volume
being divided by x to begin with?
The galaxy’s volume divided by x (the resulting factor
produced from Part I of the equation) represents the
quadrant a hypothetical Drake planet resides in.
Why take the cubic root of volume divided by x?
Light moves in a straight line in all directions (due to the
universe we live in being a “flat” universe it has no
curvature); Therefore it is in essence 1 Dimensional, as
opposed to the 3 Dimensional calculation of volume

9. Simply put, if the volume of the quadrant a possible
Drake planet resides in is represented by “V” and the
distance light needs to travel to reach a certain point is
“y” then…
And with the miracle of mathematics the equation can
be rewritten as:

10. Even more simply put, look at
this rubix cube:
 The cube has a height of three
units, a width of three units, and
a length of three units
 How do you find the volume?
 3 x 3 x 3 = 27 cubic units
 Suppose you only knew the
volume, and you needed to find
the height/width/length.
 You would need to find the cubic
root of 27 units, which is 3.

11.  400 Billion = # of stars present
in galaxy
 15% = % of stars with planets
 37.5% = % of planets in the
habitable zone
 50% = % of habitable planets
with life
 1% = % of habitable planets
with life that have developed
interstellar communications
 12.2 Billion = age of the galaxy
 10,000 = mean # of years
communicative civilizations
remain active

12. Radius of the Milky Way Galaxy: 50,000 light
years
Height of the Milky Way Galaxy: 1000 light years

13. Part I: (400,000,000,000 x .15 x .375 x .5 x .01)
/(12,200,000,000 / 10,000) = 92.213
Part II: =
85,174,944,517.67

14.  There are an estimated 92 Drake planets. That is, there are 92
planets in the Milky Way galaxy with extant interstellarly
communicative life forms.
 If these planets were uniform in distance throughout the Milky
Way galaxy, there would be one interstellarly communicative
civilization per 85.2 billion cubic light years.
 This space is approximately 1% of the volume of the galaxy in its
entirety (1.08%).
 But, light travels in a straight line. Meaning y (light years needed
to travel to the nearest interstellarly communicative civilization)
would be = 85,174,944,517 which is 4,399.8 light years.

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N.p., 25 Aug 2005. Web. 18 Oct 2011.
<http://messier.seds.org/more/mw.html>.
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University Of Chicago News Office. N.p., 01 Jul 2005. Web. 18 Oct 2011.
<http://www-news.uchicago.edu/releases/05/050629.milkyway.shtml>.
 Ohio State University. "In all the universe, just 15 percent of solar systems are
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<http://www.sciencedaily.com/releases/2010/01/100105161540.htm>