[RD] Daily Graphs and Charts

[CavLancer]

My doctor tells me I'm type 1 or 2 or something. Anyway I'm way ahead of you zeros.

 

[Cutlass]

I tried to find someone who "did the math", and I found this:

Spoiler :

Dyson originally calculated that there is enough matter in the solar system to create a shell at least three meters thick, but this might be an overestimate since most matter in the solar system is hydrogen and helium, which isn't usable as building materials (as far as we know today). They could presumably be fusioned into heavier elements, but if you can fusion elements on that scale, why bother with a dyson sphere?
If one assumes that all elements heavier than helium are usable (a slight exaggeration), then the inner planets are completely usable, as is the asteroid belt.

Mass (1e24 kg)

Mercury: 0.33022
Venus: 4.8690
Earth: 5.8742
Moon: 0.0735
Mars: 0.64191
Asteroids: ~0.002

Sum: 11.78733e24 kg
It is a bit more uncertain how much of the outer planets is usable. Jupiter and Saturn mainly consist of hydrogen and helium, with around 0.1% of other material. Jupiter is assumed to have a rock core massing around 10-15 times the Earth, and Saturn probably contains a smaller core massing around 3 times the Earth. Uranus and Neptunus seem to be mainly rock and ice, with around 15% hydrogen, so a rough estimate would be around 50-70% usable mass. Pluto seems to be around 80% usable.

Mass (1e24 kg) Usable Mass (rough estimate)

Jupiter: 1898.8 ~58
Saturn: 568.41 ~17
Uranus: 86.967 ~43
Neptune: 102.85 ~51
Pluto: 0.0129 ~0.01
Kuiper belt objects: ~0.02 ~0.016

Sum: 2657.06 Usable: ~170

(this is based on the assumption that the size distribution of the Kuiper belt mirrors the asteroid belt)
(these tables based on information from Physics and Chemistry of the Solar System by John S. Lewis and The Nine Planets by Bill Arnett)

The inner system contains enough usable material for a dyson sphere. If one assumes a 1 AU radius, there will be around 42 kg/m^2 of the sphere. This is probably far too little to build a massive type II dyson sphere, but probably enough to build a type I dyson sphere where mass is concentrated into habitats and most of the surface is solar sails and receivers, which can presumably be made quite thin.

With the extra material from the outer system, we get around 600 kg/m^2, which is enough for a quite heavy sphere (if it was all iron, it would be around 8 centimeters thick, and if it was all diamond around 20 centimeters).

A Type III shell, a "dyson bubble", would have a very low mass. Since its density is independent of the radius (see the stability section), its mass would scale as r^2. For an 1 AU bubble, the total mass needed would be around 2.17e20 kg, around the mass of Pallas

At first glance that seems wildly unrealistic, since you can't just dismantle the entirety of Mercury or Venus and use every single atom in the construction of the dyson sphere. It seems obvious to me that you could only really use a small % of a planet's makeup in the construction of this thing, but.. I suppose if you sent in a bunch of nanobots to do the job for you, atom by atom, it might be doable, but it still seems like a super fantastical proposition. When we build stuff here on earth and in space, we use, what, a tiny % of the makeup of the Earth to accomplish this, let's say maybe only 1% of all of the Earth's mass is stuff you can mine and/or use, realistically speaking, it seems that for most major projects on this planet and beyond (ISS) we use a super tiny fraction of that small fraction.

So.. yeah it seems like an unrealistic estimate, unless we have the technology to dismantle planets from 100% to 0% and use all the atoms in the construction of the sphere, somehow. With today's technology and even tomorrow's technology, it seems you're right, there just isn't enough stuff in the solar system to use to build such a thing.

By the time you have the ability to build a Dyson's Sphere, you can fully dissemble a planet. It's pretty much a prerequisite.

 

[El_Machinae]

If you want something even less encouraging, MinutePhysics recently did a video on how most people fall into the majority of any given group and thus we're looking for intelligent alien life in all the wrong places.

Spiffy! So, then, the people salivating at the idea of Europa being a 'model' might have the right idea. There would be more opportunities for life to occur in small, cold planets than large ones in the Goldilocks zone ...

 

[JohannaK]

There could always be a small chance that we're the bigger, less dense intelligent life, even if the contrary is far more likely.

 

[Hygro]

So... Giants on Titan? Smaller planet, thicker atmosphere, less sunlight...

 

[hobbsyoyo]

Probably not. The problem with Titan is a lack of a good energy source. You can have great chemistry (Titan certainly does) but without that 'spark' to get things moving, they won't.

It's a cold planet so unless there is a warm underground ocean there, there is very little chance of their being any life, much less complex life.

 

[Hygro]

What if the life is reeeaaaaaalllly big so it's super efficient. Like there's one giant fungus huddling itself for warmth, that crawled/plant-walked over to the other side of the planet when our cameras arrived.

 

[hobbsyoyo]

The problem is that life will only get to be super efficient after a very long evolutionary process. Think about it as having lots of design cycles.

For Earth, the design cycles were super short because there was lots of available energy to keep things moving. Early organisms were born, ate, reproduced and died in a day or two at most. On Titan, while there could be life, there is so little energy that the cycles would be super long to say the least. So there would have been many fewer cycles and hence less advanced/efficient life there, if there is life at all.

For example, the mitochondria in your body can munch a molecule of ATP in a fraction of a second or whatever to get energy. An analogous process with hypothetical Titan life might take like 10 years to happen to completion. **made up numbers for illustrative purposes only


Oh and our cameras caught only the tiniest of tiny slices of the surface at any decent resolution so a hypothetical giant would have only had to move a few inches to be out of view. Unless of course it was so big it is visible from space. In which case it wouldn't be moving anywhere in a hurry.

 

[Gigaz]

So.. yeah it seems like an unrealistic estimate, unless we have the technology to dismantle planets from 100% to 0% and use all the atoms in the construction of the sphere, somehow. With today's technology and even tomorrow's technology, it seems you're right, there just isn't enough stuff in the solar system to use to build such a thing.

Even with perfect technology it might take a long time to dismantle a planet and it might be more efficient to go to the nearest supernova remnant and send a lot of useful debris back to the solar system before it ends up in a star where it's helping noone.

 

[Paul in Saudi]

Firearm deaths in the US; Children v Law Enforcement Officers (Source Politifact)

 

[warpus]

By the time you have the ability to build a Dyson's Sphere, you can fully dissemble a planet. It's pretty much a prerequisite.

Hmm are you saying that because otherwise there would just not be enough material to construct the dyson sphere out of?

The only issue I take with your statement is that it's possible to imagine a solar system in which building materials are a lot more easily accessible. Like say, maybe most of the solar system is made up of meteor belts? Or like, maybe you've sent dyson sphere constructor ships to a solar system that's just forming and doesn't have planets yet, just debris?

In most cases I agree, but it doesn't seem to me to be a prerequisite per se.

 

[Cutlass]

Hmm are you saying that because otherwise there would just not be enough material to construct the dyson sphere out of?

The only issue I take with your statement is that it's possible to imagine a solar system in which building materials are a lot more easily accessible. Like say, maybe most of the solar system is made up of meteor belts? Or like, maybe you've sent dyson sphere constructor ships to a solar system that's just forming and doesn't have planets yet, just debris?

In most cases I agree, but it doesn't seem to me to be a prerequisite per se.

We don't really know what the composition is going to be. So we can imagine a lot of scenarios. But I think you wouldn't want to leave a planet in existences within the sphere. Balancing the environment of the sphere is going to be difficult enough. Fact is, I don't think it's possible. But on the theory that someone could build one, I suppose you can make the assumption that they could overcome those other problems as well.

I was recently reading a novel in which this group broke up planets like Earth by building strips of iron encircling them. And then using magnetic forces to increase the planetary spin to the point where centrifugal force pulling the planet apart exceeded the gravitational force holding it together, resulting in it shattering the planet.

 

[warpus]

Sounds interesting, what novel is that?

 

[Cutlass]

Sounds interesting, what novel is that?

The Long Utopia by Terry Pratchett and Stephen Baxter


http://www.amazon.com/The-Long-Utopia-Earth-Book-ebook/dp/B00NLM3IKI/ref=dp_kinw_strp_1

 

[El_Machinae]

Introducing a new metric: a cubic mile of oil. Allows us to translate between btu and kWh and billions of gallons, etc.

 

[really]

Itroducing a new metric: a cubic mile of oil. Allows us to translate between btu and kWh and billions of gallons, etc.

 

[Arwon]

Introducing a new metric: a cubic mile of oil. Allows us to translate between btu and kWh and billions of gallons, etc.

I'm not a fan of global primary energy as an all-in indicator. Many of those products convert to usable energy at quite different rates. Thermal efficiency differs for fossil fuels being converted to electricity (and also in refining efficiency and use in transport), renewable energy is mostly measured at the point of electricity generation so there's no thermal efficiency equivalent, and isn't thermal efficiency not really *the issue* with nuclear power but rather slowing the reaction down enough?

I think a more fruitful comparison is tracking final energy consumption back to its source. That accounts for the differing efficiencies in turning supply into use.

 

[Gigaz]

That seemed like a surprisingly low percentage for renewables till I figured that 2006 is already 10 years past.

 

[Cutlass]

That's also 'energy', not 'electric production'. So it includes motor transport fuel, which is virtually all oil.

 

[really]