Because when I looked for an explanation, it wasn’t exponential: https://foothill.edu/psme/daley/tutorials_files/10.%20Error%...
Indeed, and today, the bulk of our communications are via enclosed waveguides -- fiber optics. And our remaining wireless communications are quickly evolving towards both decreasing power use and signal formats that are nearly indistinguishable from noise. Our period of "hot" radio emissions may only span roughly a century.
Radio is really only viable at the moment because pretty much all communications goes to or from Earth (sometimes via relay) and on Earth we can build massive radio dishes to transmit very powerful signals, and enormously amplify reception. In the future a lot of comms will be between points other than Earth, and in many of those locations radio antennas many dozens of metres across won't be viable. I think at that point we'll most likely switch to lasers for communications over interplanetary ranges. Starlink are planning to use lasers for their sat-to-sat relay links.
Yes, absolutely. The main reason is that building orbitals is largely an engineering problem. You need a material no stronger than stainless steel. If graphite is feasible, it allows you to build bigger orbitals but it's not necessary.
Compare this to a lot of other proposed megastructures like space elevators, which would take a material to build that doesn't currently exist.
Also, to be clear, we're talking about Dyson _Swarms_. This is the original design idea that was called Dyson Spheres but that name is often not used because people mistakenly think we're talking about a rigid shell that encompasses a star. That is not and never was the intent. It's also impossible for many reasons.
A Dyson swarm is simply a collection of orbitals. The great thing about it is you can also build it incrementally.
Note that since these are spinning orbitals they have (spin) gravity and atmospheres.
Energy is absolutely a factor here.
Thank-you for clearing this up for me. I made a post after you, but you addressed the issues that I discarded. I now know more then I did. Thanks!
If I remember, Isaac Arthur on YouTube[1] explained that space elevators would not need exotic material, they could be built out of steel or stone if you had enough of it - you'd end up with an inverted pyramid of steel chain so wide at the base that the forces were distributed enought that nowhere was stressed past the breaking point of steel.
Not very practical today, but if humans never do develop Ringworld Scrith, not ruled out entirely.
[1] https://www.youtube.com/results?search_query=isaac+arthur+sp...
Also, to remain in a stable orbit, wouldn't the spin force have to match the gravity of the star? So there would be no effective force left to provide gravity would there? (Similar to how people on the ISS are weightless despite still being within earth's gravity well).
What? Civilization runs on cheap, abundant energy. Before the industrial revolution we had to use labor animals, slaves and the occasionally water and wind mill. Providing light was expensive. Global supply chains (transportation), aluminium smelting, fixing nitrogen for fertilizer or calcination for cement consume stupendous amounts of energy.
If energy became cheaper then creating green fuel for airplanes and rockets, electrorefining all metals, desalination or perhaps mining and crushing olivine rocks for carbon sequestration would become more feasible.
Whenever vertical farming is discussed here the main counter-argument boils down to energy not being cheap enough. It's hard to compete with the sun delivering it to plants for free.
It looks like we'll move on from that, though the devil is in the details. :-)
Besides, surely it must be simpler to build a fusion reactor on earth than harvesting enough material to cover the sun in solar panels. Would the solar system even have enough resources for that?
That's only true for low values of civilization. Even bronze age tech consumes more than hunter-gatherers which consume more than monkeys.
> Besides, surely it must be simpler to build a fusion reactor on earth than harvesting enough material to cover the sun in solar panels.
Dyson swarms sit higher on the kardashev scale than harvesting whatever you can get on a single planet. At some point waste heat rather than fuel will also become a real problem. Fusion reactors are ultimately thermal power stations, glorified steam engines.
> Would the solar system even have enough resources for that?
You'd start small with asteroids. And then disassemble some moons with shallow gravity wells. Which of course again requires stupendous amounts of energy just to move the material around but the sun still has billions of years left so there will be time to recoup that investment.
I don't lack for aluminium or even transatlantic flights (the most energy intensive think I could think of buying). If I really want to go to X I do. Price doesn't really bother me.
Maybe we can use 10x the current supply so everyone can have my lifestyle. But that's still vastly less than a Dyson sphere would produce.
For a long time energy was a limiting factor on human development. But I don't think that's true for the average westerner anymore. I want time off and less stress and relationships. Those mostly come down to social structures and information, not GJs...
Not quite. You have more than enough energy for what you could imagine using it for. But I guarantee you that a greater abundance of cheap energy will create new uses for that energy. That's how its worked for the entire of human history.
The amount of energy we're talking about here is mind-boggling, almost incomprehensible.
Typically we talk about this in the Kardashev scale (and usually the Sagan normalized variant). The short version of this is that:
- A Kardashev-1 (K1) civilization uses all the energy out planet collects from the Sun, estimated at around 10"16 Watts;
- A K2 civilization uses all the energy output by the Sun, estimated at 10^26W
- A K3 civilization uses all the energy produced by the stars in our galaxy, estimated at 10^36W.
We are roughly a K0.6-0.7 civilization on this scale. Human energy consumption I believe is estimated at 10"11W.
So a K2 civilization has access to 1 million billion times what we have now. It's like if every person on Earth had access to 140 million times the Earth's energy usage.
You don't. You only think you do because you are living on borrowed energy, massive amounts of energy stored in carbon over the last billion years. Unleashing this stored energy is going to burn down our planet.
So yes, we need way more energy that is not tied to digging up dead dinosaurs. Even more energy if we want to put them back in the ground. And even more if everyone wants clean water. Everyone else that is not a westerner wants lights and water and food too.
Consider also that in order to grow human population at some point you start to need large amounts of energy to colonize new space, be it planetary, on asteroids or spade stations.
If more energy becomes available, demand for it will scale accordingly because of new possibilities.
“2018, global energy-related CO2 emissions rose 1.7% to a historic high of 33.1 Gt CO2.”
Only thinking of your electricity or transport needs is missing all the other CO2 sources you rely on for your civilisation. For example you eat: “Globally, the fertiliser industry is responsible for about 1.5% of annual carbon emissions, largely because 95 per cent of production relies on natural gas as a feedstock.”.
The easiest proxy for measuring your energy usage is simply the amount you spend annually, which is usually closely related to the amount you earn. Most of our energy usage is hidden throughout our economy, due to our reliance upon our society.
Maybe we will consume vast resources of energy sending people or machines to explore the universe. Maybe we will need it to reshape our home environs. Maybe we will want to produce more people than can be supported on planet earth and profit in the arts and sciences from their contributions?
Never in human history has any amount of energy been enough so is simple extrapolation that if civilization continues to grow it will consume more energy.
The big differences between us and those merchants (healthcare, communications etc) are matters of technology not energy.
Proper sewers and drinking water has added much more to our lives than cars vs coachs.
And that's what I see going forwards too: I want a longer healthier life. But that will be a matter of medical discovery, not a CAT scanner than uses 1 million times more power...
We are nearly 40x as energy intensive per capita as as were just 2 centuries ago. If we rewind the clock to 1400 it becomes harder yet to compare because we actually captured so very little energy.
For example, if you start building space habitats (even if they are enclosed cylinders such that they hold an atmosphere and provide gravity via rotation) you need to put them somewhere. It makes sense to throw them in orbit around the star at some optimal distance (for example at 1AU +/- some amount), if you continue to put more and more such habitats around a star in similar orbits over time, in sufficient numbers, wouldn't they start to resemble a Dyson swarm?
That's essentially what a full Dyson Swarm looks like.
People have modeled how many orbitals you'd need to achieve this and I believe that if you orbit them at 1 AU (plus or minus) the mean distance between them is still around 150,000km.
What Dyson Sphere's excel at is hiding their location* and capturing 100% of a stars output. At those sizes, a civilization MUST have already conquered the energy problem. It'd be impossible to construct without "free energy", because you need to convert that energy into matter to make/engineer enough material to create a sphere the size of the Goldilocks zone.
And as you said, you'd lose atmosphere & gravity* would be wonky.
But to address the fine article, the equation was a thought experiment. We now have hard data on the number of stars that we've looked at that have planets. And of those we have a hard number that have planets in the habitable zone. The Drake Equation presumes that you guess TINY numbers for those values. Well using known numbers and extrapolating the number of possible worlds with intelligent life jumps from staggering large, to incomprehensible.
As humans, we can barely communicate with others of our own species. Let's frame the problem another way.
Put two Americans in a room. One is deaf, the other is blind. How long does it take for them to agree on what to eat for dinner?
Context depends on language. We may have been bombarded by intelligent alien life for centuries; we just don't know that somebody is talking.
*Everybody forgets about gravity.
There possibly are ever more exotic applications that require more energy. Energy to matter conversion which you mention (and which also conveniently produces antimatter) requires very very large amounts of energy. The mass defect of the Tsar Bomba is merely 2.6kg, which also happens to be roughly equivalent the energy the sun that hits the whole planet each second. And then there are speculative things like the alcubierre drive or anything that involves moving entire stars.
Just FYI, but the Ringworld as Larry Niven envisioned it simply doesn't work because no known or theorized material is remotely strong enough.
To produce gravity a Ringworld needs to orbit the star. This produces centrifugal force that is tearing the ring apart. I believe around our Sun it would need to spin at about 1.2M mph [1].
[1]: https://www.bbc.com/future/article/20150609-will-we-ever-bui....
What has changed is the assumptions about how we would detect a starfaring civilization. 60 years ago we were assuming radio communications because that seemed to be where our future was and, by extension, what we might expect other civilizations to do.
Obviously the values in the equation are unknown. We use such things to frame problems that involve unknowns like this. A good example: the anthropic principle [1].
Anyway, the more prevalent line of thinking now is that starfaring civilizations are likely to end up building Dyson swarms. This is a long and complex discussion. There are many objections but those objections tend to suffer from the problem that, if that objection is true, there should be more not less starfaring life (eg any form of FTL).
If matter is the ultimate limiter to civilizations then it makes sense that civilizations will try and amass as much of it as possible. It doesn't matter if not every civilization goes this route because even one such galaxy-spanning civilization within a million light years will stand out (based on the IR signature).
Even without that it probably wouldn't take more than about 10M years for humanity to colonize the Milky Way.
[1]: https://en.wikipedia.org/wiki/Anthropic_principle