If Loud Aliens Explain Human Earliness, Quiet Aliens Are Also Rare
Given these two constraints:<p>1. The speed of light is a hard speed limit. This means there&#x27;s also no cheating with warp drives, other forms of FTL, crossing dimensions, parallel universes or time travel; and<p>2. The laws of thermodynamics as we understand them hold true.<p>then the outcome of spacefaring civilization I believe is generally inevitable. That is, the ultimately limiting factor is energy and mass.<p>The easiest way to get both is with Dyson Swarms. This requires no new physics and no exotic materials.<p>If so, then a galaxy-spanning civilization is going to be completely obvious from a million light years away from the spectrum. Why? Because a full Dyson Swarm would have a very unique spectrum, specifically very little visible light and a lot of IR. That&#x27;s just basic physics. The only realistic way to get rid of heat in space is to radiate it away and the wavelength of that is a function of temperature.<p>This is discussed in the context of the Fermi Paradox, which has the advantage that you don&#x27;t need to determine what every alien civilization does, you just need to know if there are any exceptions.<p>Example: if there were 1000 spacefaring civilizations in the Milky Way, what are the odds that all 1000 of them (assuming they were within out light cone) would remain quiet or hidden? Couple that with mass and energy ultimately being limited then there is a strong incentive and advantage in becoming as large as possible. So even if 99% of civilizations remain quiet, the 1% will still make themselves visible.<p>Additionally, on the notion of hidden civilizations in particular, it&#x27;s essentially impossible to remain hidden to a K2 or K3 civilization so there&#x27;s really no point.<p>This is what gives me confidence that the Milky Way isn&#x27;t teeming with spacefaring life. In fact I consider it much more likely we&#x27;re the only such civilization in the Milky Way (within our light cone).