The Drake equation tries to estimate the number of advanced civilizations. The numbers depend on the input assumptions, but they always end up coming out reasonably large. In other words, it seems very likely the Universe is teeming with life. It is hard to imagine that it isn't.
The Fermi paradox indirectly argues against that by saying "if there are so many (civilizations) out there, where are they and why haven't we heard from them?". The "paradox" isn't really a paradox at all. It is easily explained by distance. The nearest star is just over 4 light years away. The nearest confirmed planet is over 16 light years away and there are only 4 confirmed planets within 20 light years (so far anyway).
Relativity guarantees that those are prohibitive distances for travel and the inverse square law makes them prohibitively difficult for radio detection. So no real paradox. The great surprise would be if we ever actually did get concrete evidence of alien civilization.
The drake equation is an attempt to ballpark the number of intelligent species. Many of its estimates say that there should be lots of intelligent species. The Fermi paradox is that we don't see any intelligent species, indicating that there is some other factor we aren't taking into account. Depending on what that factor is, we may have cause to be worried. Some think it's just a matter if timescales; intelligent civilizations that occur collapse in a short enough time span that the chance of one existing close.enough to us in both space and time is low. Another concept.is the great filter, where there is something that kills off (most, if not all) civilizations before they reach a certain point. If that point is behind us, we may have managed to survive, but if it is ahead of us there may be a great danger we will face in the future. Nuclear weaponry is one possible filter; perhaps most species self annihalate when they get it. Other filters are more.mundane; we don't see any galaxy spanning civilizations because it is too hard and resource intensive, and so nobody ever does it. This means that civilizations may persist for long times, but have natural limits on their growth. Yet another possible resolution is that there are advanced civilizations, but they are so advanced we don't.know how to detect them. A few centuries ago we didn't know about radio, and would not.have been able to detect a civilization using it to communicate, perhaps radio is not the ultimate form of.communication. A narrow beam communication could be used instead, say laser guided signals. This would be more.energy effecient for.them, but not create the leakat that.broadcasting does, so there is nothing for us to detect. Or even more.mundane, they are broadcasting radio waves, but they are too weak for us to.detect at this distance. This is rather plausible, as we couldn't detect esrtbs radio signals with our best equipment from a few light years away.
The Drake equation attempts to estimate how many intelligent alien civilizations there might be. On most attempts to plug numbers in, we get a relatively high number of alien civilizations. Partly this is just a function of how big the galaxy is.
The Fermi paradox notes this, and then asks "well ... Where are they then?" If intelligent extra terrestrial life is somewhat common, we would expect to see some of it. Yet, we currently have no evidence aside from the laws of chance that we are not alone in the universe. That's the (informal) paradox.
Personally, I find this fascinating. I really hope we are not alone.
0 Comments