New light shed on intelligent life existing across the galaxy

Date:
June 15, 2020
Source:
University of Nottingham
Summary:
Is there anyone out there? This is an age-old question that
researchers have now shed new light on with a study that calculates
there could be more than 30 intelligent civilizations throughout
our Galaxy. This is an enormous advance over previous estimates
which spanned from zero to billions.



FULL STORY ========================================================================== [Illustration of alien | Credit: (c) Trifonenko Ivan / stock.adobe.com] Illustration of alien world, starry background (stock image).

Credit: (c) Trifonenko Ivan / stock.adobe.com [Illustration of alien |
Credit: (c) Trifonenko Ivan / stock.adobe.com] Illustration of alien
world, starry background (stock image).

Credit: (c) Trifonenko Ivan / stock.adobe.com Close One of the biggest
and longest-standing questions in the history of human thought is whether
there are other intelligent life forms within our Universe.

Obtaining good estimates of the number of possible extraterrestrial civilizations has however been very challenging.


==========================================================================
A new study led by the University of Nottingham and published today in
The Astrophysical Journal has taken a new approach to this problem. Using
the assumption that intelligent life forms on other planets in a similar
way as it does on Earth, researchers have obtained an estimate for the
number of intelligent communicating civilizations within our own galaxy --
the Milky Way.

They calculate that there could be over 30 active communicating
intelligent civilizations in our home Galaxy.

Professor of Astrophysics at the University of Nottingham, Christopher Conselice who led the research, explains: "There should be at least a
few dozen active civilizations in our Galaxy under the assumption that
it takes 5 billion years for intelligent life to form on other planets,
as on Earth." Conselice also explains that, "The idea is looking at
evolution, but on a cosmic scale.

We call this calculation the Astrobiological Copernican Limit."
First author Tom Westby explains: "The classic method for estimating
the number of intelligent civilizations relies on making guesses of
values relating to life, whereby opinions about such matters vary quite substantially. Our new study simplifies these assumptions using new data, giving us a solid estimate of the number of civilizations in our Galaxy.

The two Astrobiological Copernican limits are that intelligent life
forms in less than 5 billion years, or after about 5 billion years --
similar to on Earth where a communicating civilization formed after 4.5
billion years. In the strong criteria, whereby a metal content equal to
that of the Sun is needed (the Sun is relatively speaking quite metal
rich), we calculate that there should be around 36 active civilizations
in our Galaxy." The research shows that the number of civilizations
depends strongly on how long they are actively sending out signals of
their existence into space, such as radio transmissions from satellites, television, etc. If other technological civilizations last as long
as ours which is currently 100 years old, then there will be about 36
ongoing intelligent technical civilizations throughout our Galaxy.

However, the average distance to these civilizations would be 17,000
light- years away, making detection and communication very difficult
with our present technology. It is also possible that we are the only civilization within our Galaxy unless the survival times of civilizations
like our own are long.

Professor Conselice continues: "Our new research suggests that searches
for extraterrestrial intelligent civilizations not only reveals the
existence of how life forms, but also gives us clues for how long our own civilization will last. If we find that intelligent life is common then
this would reveal that our civilization could exist for much longer than
a few hundred years, alternatively if we find that there are no active civilizations in our Galaxy it is a bad sign for our own long-term
existence. By searching for extraterrestrial intelligent life -- even
if we find nothing -- we are discovering our own future and fate."

========================================================================== Story Source: Materials provided by University_of_Nottingham. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Tom Westby, Christopher J. Conselice. The Astrobiological
Copernican Weak
and Strong Limits for Intelligent Life. The Astrophysical Journal,
2020; 896 (1): 58 DOI: 10.3847/1538-4357/ab8225 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/06/200615092753.htm

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