From [Wikipedia](https://en.wikipedia.org/wiki/Dyson_sphere):

>  A **Dyson sphere** is a hypothetical megastructure that encompasses a star and captures a large percentage of its power output. The concept is a thought experiment that attempts to imagine how a spacefaring civilization would meet its energy requirements once those requirements exceed what can be generated from the home planet's resources alone. Because only a tiny fraction of a star's energy emissions reaches the surface of any orbiting planet, building structures encircling a star would enable a civilization to harvest far more energy.

With this definition in mind, consider the following thought experiment. Suppose we send probes to outer space and eventually discover a colossal spherical megastructure around a star, reminiscent of a *Dyson sphere*. For the sake of argument, assume we can be certain of the following facts:

* The megastructure appears perfectly spherical.
* The megastructure is clearly *not* debris, space dust, or small meteorites that we are misinterpreting as a megastructure. Assume we can confidently rule out these alternative explanations.
* The megastructure is composed of materials not found on Earth, nor known to be carried by meteorites or asteroids.
* At this point, we don't know if aliens exist; claims that aliens built it could be countered by skeptics with the "aliens of the gaps" objection.
* No human on Earth has any clue about how such a megastructure could be assembled by design. The materials and their properties are completely unknown to us, and the way the building blocks of this structure were assembled doesn’t resemble any known method or technology on Earth. We have no concept of how to transport and assemble such a structure around a star.
* Therefore, any attempts to draw analogies between this Dyson sphere and human technology to infer design can be considered fallacious (see this [answer](https://philosophy.stackexchange.com/a/118035/80226), critiquing arguments from analogy in response to https://philosophy.stackexchange.com/q/118024/80226).
* For all we know, we cannot 100% rule out chance as a possible explanation (see this [answer](https://philosophy.stackexchange.com/a/118073/80226) to https://philosophy.stackexchange.com/q/118072/80226).

Given these considerations, how can we explain the existence of a Dyson sphere?

I can see at least the following hypotheses:

* **H1**: The Dyson sphere formed by chance through unguided natural processes. This [answer](https://philosophy.stackexchange.com/a/118073/80226) entertains the possibility that many counterintuitive, improbable events might happen by chance due to quantum tunneling, so in principle, we should remain open-minded about this.
* **H2**: The Dyson sphere was designed by an unknown intelligence (certainly not us, but if not us, this raises many questions, such as who? how? when? where did the designer come from? was the designer itself designed by another designer? etc.).
* **H3**: The Dyson sphere is simply a brute fact.
* **H4**: The Dyson sphere is a brute contingency, appearing out of nothing for no reason, and that’s all there is to it.

If there are other hypotheses worth considering, readers are welcome to add them.

At first glance, H1 may seem extremely implausible. We have never observed natural processes assembling Dyson spheres by chance, so we have no empirical observations to support this hypothesis. Moreover, this [answer](https://philosophy.stackexchange.com/a/118783/80226) introduced the concept of the [*universal probability bound*](https://en.wikipedia.org/wiki/Universal_probability_bound) coined by William A. Dembski, according to which our observable universe has an estimated upper limit of 10<sup>150</sup> distinct events. If the probability of a Dyson sphere forming by chance around a star is significantly lower than 1 in 10<sup>150</sup>, then the following quote from Dembski would apply:

> A degree of improbability below which a specified event of that probability cannot reasonably be attributed to chance regardless of whatever probabilitistic resources from the known universe are factored in.

However, if our universe is just one of an *infinite* number of universes in a multiverse, then H1 may not seem as implausible as before. We might apply some version of the [Anthropic Principle](https://en.wikipedia.org/wiki/Anthropic_principle) to Dyson spheres, suggesting that we just happen to be in a universe where a Dyson sphere formed by chance. But we shouldn’t be too quick here; a more careful analysis is needed. Even in an infinite multiverse, proportions may matter: from the infinite universes that host human life, how many also contain Dyson spheres? Perhaps only a tiny fraction of these infinite universes contains both humans *and* Dyson spheres, making it exceedingly unlikely to observe a Dyson sphere even if we assume the existence of human life, and thus we may see H2 as more plausible. However, when dealing with infinite sets, counterintuitive paradoxes, like [Hilbert's hotel](https://en.wikipedia.org/wiki/Hilbert%27s_paradox_of_the_Grand_Hotel), can arise, and probabilities might not behave consistently, so it’s unclear how much weight a probability argument should hold in the context of infinite sets.

Notice that through these thoughts, I’m just trying to emphasize the fact that the discussion can be quite nuanced and involve multiple considerations.

**So, if we come across a Dyson sphere, even in an infinite multiverse, can we reasonably conclude that this is strong evidence for H2 (design)?**