2 hours ago, dmwalker said:

How would one know what is considered excessive for another planet and how could one assume it's as a result of burning fossil fuels. I'm thinking of a planet like Venus or even Mars.

 

Isotopic signature. Various sources of CO2 have a distinctive isotopic signature. So if we see the isotopic signature, in the atmosphere,  from what should be fossilised carbon under the ground, its a possible techno-signature. 

43 minutes ago, dmwalker said:

I admit my imagination is still stuck in the 20th century but I can't imagine anyone taking these concepts seriously. Why would one build a ringworld in the first  place and, if a ringworld is big enough to be detected from here, how could one provide an atmosphere for it in the first place?

The concept of a Dyson Sphere, whether a solid sphere or a spherical array completely surrounding a star, sounds impractical, particularly from a maintainence point of view. Maybe a localised array near the home planet would be more likely.

 

Who knows what motivation might drive an alien species thousands or million of years in advance of ours. Something like a Dyson Sphere would have an enormous internal surface area. And provide more real-estate than an nearby planet. 

8 minutes ago, martin-w said:

Isotopic signature. Various sources of CO2 have a distinctive isotopic signature. So if we see the isotopic signature, in the atmosphere,  from what should be fossilised carbon under the ground, its a possible techno-signature.

Do we know the isotopic signature of the carbon dioxide on Venus and Mars? I presume not all carbon is fossilised.

12 minutes ago, martin-w said:

Something like a Dyson Sphere would have an enormous internal surface area. And provide more real-estate than an nearby planet.

It's not about real estate, though, is it? It's about harnessing solar energy.

19 minutes ago, martin-w said:

Who knows what motivation might drive an alien species thousands or million of years in advance of ours. Something like a Dyson Sphere would have an enormous internal surface area. And provide more real-estate than an nearby planet. 

I'm sorry, but the concept of a solid Dyson sphere doesn't work. I don't understand why so many are fantasising about this. Dyson himself recognised that it's gravitationally unstable, and proposed other "solutions" with their own problems.

Pascal

Edited July 8, 20214 yr by Pascal_LSGC

24 minutes ago, dmwalker said:

Do we know the isotopic signature of the carbon dioxide on Venus and Mars? I presume not all carbon is fossilised.

 

Not all carbon is fossilised correct. And different sources have their own signature. But we know the isotopic signature of fossilised carbon that is being burnt. So if we see it in an atmosphere its a techno signature. 

28 minutes ago, dmwalker said:

It's not about real estate, though, is it? It's about harnessing solar energy.

 

Harnessing energy yes. But it also provides many orders of magnitude more real estate. 

49 minutes ago, Pascal_LSGC said:

I'm sorry, but the concept of a solid Dyson sphere doesn't work. I don't understand why so many are fantasising about this. Dyson himself recognised that it's gravitationally unstable, and proposed other "solutions" with their own problems.

Pascal

 

You could well be right. It was just an example of what a techno-signature is. Just an example. 

 

I can't see anything about gravitational stability though. Where did you see that? 

 

https://en.wikipedia.org/wiki/Dyson_sphere

 

Quote

Although such megastructures are theoretically possible, building a stable Dyson sphere system is currently beyond humanity's engineering capacity. The number of craft required to obtain, transmit, and maintain a complete Dyson sphere exceeds present-day industrial capabilities. George Dvorsky has advocated the use of self-replicating robots to overcome this limitation in the relatively near term.^[6] Some have suggested that such habitats could be built around white dwarfs^[7] and even pulsars.^[8]

 

Edited July 8, 20214 yr by martin-w

1 hour ago, martin-w said:

I can't see anything about gravitational stability though. Where did you see that? 

I think it's the following statement in the section about Dyson swarms in you referenced article:

"Disadvantages resulting from the nature of orbital mechanics would make the arrangement of the orbits of the swarm extremely complex. The simplest such arrangement is the Dyson ring, in which all such structures share the same orbit. More-complex patterns with more rings would intercept more of the star's output, but would result in some constructs eclipsing others periodically when their orbits overlap.[11] Another potential problem is that the increasing loss of orbital stability when adding more elements increases the probability of orbital perturbations."

Or maybe it's this:

https://physics.stackexchange.com/questions/40739/is-dyson-sphere-a-stable-construction

Edited July 8, 20214 yr by dmwalker

1 hour ago, martin-w said:

Harnessing energy yes. But it also provides many orders of magnitude more real estate.

Yes, but what can you do with a million billion trillion times (I  have no idea what it would be) more real estate and how many planets would you need to consume in order to construct it?

2 hours ago, Pascal_LSGC said:

I'm sorry, but the concept of a solid Dyson sphere doesn't work.

Build the Dyson sphere and then...

...install 1.3 quadrillion Dyson vacuum cleaners to suck all of the vacuum from inside it. 😵

31 minutes ago, dmwalker said:

Yes, but what can you do with a million billion trillion times (I  have no idea what it would be) more real estate and how many planets would you need to consume in order to construct it?

 

What you could do with it is provide a habitat and energy source for your untold trillions of alien friends. Good point re materials though. 

We encountered a possible alien at our home. He was going door to door selling anti gravity shoes ("just soak them in water for 24 hours and they will be energized for 10 minutes of use").

5 hours ago, martin-w said:

I can't see anything about gravitational stability though. Where did you see that?

https://en.wikipedia.org/wiki/Dyson_sphere

 

I talked about a solid Dyson sphere, which I think was the first one proposed by Dyson (that should be verified, the article is unclear and contradicts itself). Quoted from himself in the article:

Quote

In response to letters prompted by some papers, Dyson replied, "A solid shell or ring surrounding a star is mechanically impossible. The form of 'biosphere' which I envisaged consists of a loose collection or swarm of objects traveling on independent orbits around the star"

See also "Dyson shell", lower in the page.

So, the "Dyson swarm" is his proposal. It's quite different from a rigid structure. It's just what Elon Musk and others are doing right now. 🙂
It gets really complicated when you want to cover a significant surface.

I didn't know the "Dyson bubble" with static "satellites" maintained by solar wind pressure. Apparently, it has also some problems.

 

On 7/8/2021 at 5:20 AM, Pascal_LSGC said:

No one has yet discovered intelligent life on Earth.

😂😂😂

I was thinking the same. Maybe we should search for some here before we look to the heavens for it, lord knows it’s getting harder to find on the blue marble we live on called earth.