Just browsing around on Astronomy photo of the day, and came across this:
Old star with dust ring.
This is a photo of an old star that still has a big ring of material around it. It has scientists flummoxed, because current theories say that young stars have such rings, but they coalesce into planets and such. But here’s an old star where that never happened.
The picture got me thinking - if an advanced civilization dismantled its planets to build a big ring around the star, is this what it would look like? Not that I’m saying that this is what it is, but in general… Would it be something you could see through? Or would it be completely opaque? The photo above is in infra-red, so for all I know it may be opaque in visible light. Also, it’s described as a ‘dust’ ring, so I imagine the density could be very low.
What would a ringworld look like? Or a dyson sphere? I imagine a dyson sphere would look pretty much like a great big planet, glowing slightly in infra-red.
Although I’m sure you noticed, I should point out that the image on that page is an illustration, not a photograph.
That said, if dyson spheres do exist it should also be possible to find spheres at various stages of construction. If I were building a dyson sphere I would first build a ring around the star, similar to the illustration you gave. Then I would build a second ring, with a plane perpendicular to the plane of the first ring.
I should think it would be difficult to detect a dyson sphere still under construction…
Larry Niven has beat you to it. Look for “Ringworld” and “Ringworld Engineers” at any used book store or in “The Big River”
Such a construct would have to be impossibly large in diamater and mass of material.
As an alternative put your talents to designing a functional PM or OU machine!
It’s impossible with existing material to build a solid object of Ringworld dimensions, yeah – but as discrete co-orbiting habitats or objects (which is what the Dyson Sphere as Freeman Dyson originally speculatively defined it was – a collection of somethings at about 1 A.U., in a spherical arrangement so that together they absorb all energy from their primary sun) it’s quite possible.
In fact, the star (I have forgotten its designation) that was second brightest in the 1840s and is now completely invisible in the visible spectrum, though quite visible in the infrared, may be a natural example of precisely what we’re talking about.
Dyson’s original conception of the sphere was not a solid spherical shell, but rather an interplanetary system so crowded with artifical construction (most importantly, solar collectors) that it would absorb almost the light from the star (since any sunlight that made it out of the system would be, essentially, wasted.)
So, speaking very casually, yes, it seems like a society on its way to building a Dyson-sphere-type system might start with something that might look basically like a dust ring. Because they would be focused on collecting light, though, I’d think they’d be producing a radially thin and vertically tall ring (call it a ribbon, say) rather than a thin, flat ring. I wonder if the IR data on old stars would allow one to discriminate between these two geometries? And are any spectral lines detected in the data that would reveal any peculiarities in the composition of the ring? To be clear, considering how common dust around old stars is, I’m assuming that there’s a natural process that gives rise to them. But it’s an interesting scenario to ponder.
As an aside, I had the privilege of hearing Dr. Dyson speak recently, and this notion of making efficient use of sunlight is still clearly resonating in his thinking. He talked of bioengineering our plantlife from green (i.e. reflecting a lot of light to avoid overheating the plant) to black (i.e. absorbing all available solar energy for maximum efficiency.) He’s a fascinating guy. If you ever have the opportunity to hear him speak, leap at it!