Imagine a Pea in a Swimming Pool

The standard size for an Olympic swimming pool is 50 meters long and 25 meters wide. Imagine a square pool half that size; 25 meters by 25 meters and around 9 feet deep. Throw into that pool a pea. The average pea is about 1/8 inch in diameter. The pool represents our galaxy, the Milky Way. The pea represents how far into the galaxy, our electromagnetic (radio and TV) ripples have spread over the last 100 years or so. 100 years from now, the pea will be twice that big or about 1/4 inch in diameter. After the ripples have been spreading for another 700 years from now, the pea will be about 1 inch in diameter. The pool will remain the same size. Our technology will have advanced.

Let’s take a look at how the Drake Equation relates to this. The Drake equation is a method for guessing how many other intelligent civilizations might exist in the universe or any specific area of space. For our purpose in this example, we’ll limit the Drake Equation to our galaxy alone.

The Universe within 50000 Light Years – [atlasoftheuniverse.com]

This map shows the full extent of the Milky Way galaxy – a spiral galaxy of at least two hundred billion stars. Our Sun is buried deep within the Orion Arm about 26,000 light years from the centre. Towards the centre of the Galaxy the stars are packed together much closer than they are where we live. Notice also the presence of small globular clusters of stars which lie well outside the plane of the Galaxy, and notice too the presence of a nearby dwarf galaxy – the Sagittarius dwarf – which is slowly being swallowed up by our own galaxy.

Our current best estimates are that the Milky Way galaxy contains about 200 billion stars and recent analysis from the Kepler space observatory suggests that there are about 100-400 billion planets in the galaxy and about 17 billion of them are earth sized. If we assume that only 1 in 10 of those has conditions suitable for developing life and only 1 in 10 with life producing potential actually produces life, we have 170 million planets with life on them in the Milky Way. If only 1 in 10 of those produces an intelligent civilization, we have 17 million intelligent civilizations in our galaxy. If only 1 in 10 of those intelligent civilizations ever develop technology capable of communicating across large expanses of space, we have 1.7 million of those.

The age of the Milky Way galaxy is estimated to be just over 13 billion years old. It takes time for stars and planets to form and for life to develop and for civilizations to reach a maturity capable of advanced technology. Our Sun is estimated to be about 4.5 billion years old and is an average age for stars in the Milky Way. We can postulate that during the first 4 billion years or so of the Milky Way, there were no civilizations and that the remaining civilizations came along at random intervals spread across about 9 billion years. If 1.7 million intelligent civilizations reached a point of technological maturity necessary to communicate across space and they did that spread out evenly across 9 billion years in time, then each advanced civilization reached maturity about 5 thousand years apart from each other in time.

A five thousand year old civilization *could* have an EM ripple “pea” about 17 meters in diameter or almost as big as the Milky Way galaxy “pool”. It took our civilization less than 100 years to go from discovering the basic principles of radio communication to achieving the start of space travel with a landing on the Moon. In only a few hundred more years, we may no longer be using EM waves for our communications and may be able to intercept the old “ripples” we’ve been sending out.

One thing is clear – that while it may be very likely that other advanced civilizations exist in our galaxy, it is very UN-likely that any pair of them will develop in either close proximity or in the same time-frame at the same pace. Any contact with aliens is going to be a huge mismatch, one way or another.

And this exercise has not even considered anything going on outside our own galaxy, which is an even smaller pea in a vastly larger pool.

SEE ALSO:
The Drake Equation
Explore the Scale of the Universe
Old Intelligence is Already Here
Singularity Theory May Explain Fermi Paradox

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