Fewer Than 10 ET Civilizations In Our Galaxy? 642
Al writes "The Fermi Paradox focuses on the existence of advanced civilizations elsewhere in the galaxy. If these civilizations are out there — and many analyses suggest the galaxy should be teeming with life — why haven't we seen them? Carlos Cotta and Álvaro Morales from the University of Malaga in Spain investigate another angle by considering the speed at which a sufficiently advanced civilization could colonize the galaxy. Various analyses suggest that using spacecraft that travel at a tenth of the speed of light, the colonization wavefront could take some 50 million years to sweep the galaxy. Others have calculated that it may be closer to 13 billion years, which may explain ET's absence. Cotta and Morales study how automated probes sent ahead of the colonization could explore the galaxy. If these probes left evidence of a visit that lasts for 100 million years, then there can be no more than about 10 civilizations out there."
How 3 Dimensional of you... (Score:4, Informative)
Re:Greed Effect (Score:3, Informative)
You're thinking of the Drake equation:
N = R* x Fp x Ne x Fl x Fe x Fi x Fc x L
http://en.wikipedia.org/wiki/Drake_equation
Without giving a lengthy description, at the beginning of the project that would grow into SETI, they asked more or less the same questions and decided that it really came down to, "What are the odds that after a given species invents radio, they invent nukes and destroy themselves?" The equation is intended to predict the number of advanced civilizations in the galaxy at any given time, based on a bunch of "educated guess," variables, like the number of planets that can support life, the number that actually do, the number of those that become intelligent, etc.
Give it time... (Score:5, Informative)
A good summary. Especially since they assume because we sent out a "identifier" once, that it is logical that all other civ's would continuously do that, just in case things change, and some youngsters show up. Instead of 1) send probes, get the info you want (or trash your orbit with satellites and crap so you can't lunch anything else) and give up, staying in your own solar system.
Not to mention we only see stuff at the speed of light, if they only send stuff at 1/10 the speed of light. Anyone over a thousand light years away hasn't even seen any signs of life in our galaxy yet, let alone had a chance to respond in a manner that we will then be able to see for a few thousand more light years.
Re:I think that there is a lack of imagination her (Score:5, Informative)
Later incorporated into his novel Diaspora
Re:0.1 the speed of light? (Score:5, Informative)
We run through the Kuiper Belt where we collide with a tiny pebble that is lazily orbiting our solar system
The relative velocity of a bullet, fired from a low velocity pistol, when it hits something is generally between 300meters/second and 600meters/second. Now imagine a bullet with a relative velocity of 150,000,000meters/second. The problem isnt the space drives.... its that the "vacuum of space" has shit in it.
FYI... (Score:3, Informative)
We still haven't killed ourselves.
Re:FYI... (Score:3, Informative)
Still alive... still alive...