Should We Build a Dyson Sphere? | Space Time | PBS Digital Studios

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Should we build it?

Yes.

👍︎︎ 20 👤︎︎ u/novkit 📅︎︎ Nov 05 2019 🗫︎ replies

9:25

Aliens build Kugelblitz black holes instead of Dyson swarm, Fermi Paradox solved

How likely do you guy think this is?

👍︎︎ 4 👤︎︎ u/tigersharkwushen_ 📅︎︎ Nov 05 2019 🗫︎ replies

Yes, and here is the man to do it.

👍︎︎ 4 👤︎︎ u/CypressBreeze 📅︎︎ Nov 06 2019 🗫︎ replies

WHAT DO WE WANT?

DYSON SPHERE!

WHEN DO WE WANT IT?

NOW!

But a question on a related note: what could we use to store whatever "excess" energy you generated?

EDIT

Read further. Thanks to the person who said "Kugelblitz black holes are batteries." Yay :D

👍︎︎ 4 👤︎︎ u/SingularBlue 📅︎︎ Nov 06 2019 🗫︎ replies

Yes.

👍︎︎ 2 👤︎︎ u/Mister_Purple_ 📅︎︎ Nov 05 2019 🗫︎ replies

Remind me in 10.000 years.

👍︎︎ 2 👤︎︎ u/Sesquatchhegyi 📅︎︎ Nov 06 2019 🗫︎ replies

Cool. I'd like to see Isaac's response to this Fermi Paradox solution.

👍︎︎ 1 👤︎︎ u/VoxVocisCausa 📅︎︎ Nov 05 2019 🗫︎ replies

Like anything, it depends on whether we need the power. You don't really need the full Dyson Swarm to do fast interstellar travel with lasers, although if you're running some enormously big set of computations you could use the power (but getting rid of the waste heat from massive amounts of redirected solar energy would be a nightmare).

👍︎︎ 1 👤︎︎ u/Wise_Bass 📅︎︎ Nov 06 2019 🗫︎ replies

I'd prefer you guys invest that time and energy into designing and building my next model Waifu 9000.

👍︎︎ 1 👤︎︎ u/TomJCharles 📅︎︎ Nov 06 2019 🗫︎ replies
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MATTHEW O'DOWD: This episode is supported by "The Great Courses plus." The idea of Dyson spheres has captured our imaginations. Vast mega structures, capable of harvesting the power output of entire stars, the as yet inexplicable Kepler Space Telescope observation of swarms of somethings partially eclipsing a distant star has led to some rampant speculation. Today we ask, are Dyson spheres plausible? And are they inevitable? In 1960, astrophysicist Freeman Dyson proposed that a sufficiently advanced civilization would have such extreme real estate and energy requirements that they might build artificial habitats in the form of vast shells surrounding their parent star. Such Dyson spheres would be possible targets for our search for extraterrestrial intelligence, appearing only as strange points of infrared lights but otherwise black at visible wavelengths. We don't really know how the energy requirements of advanced civilizations evolve. It may be that their most natural progression does not require cosmic levels of consumption. On the other hand, securing access to an entire star's energy output officially elevates a civilization to type 2 on the Kardashev scale. We're currently type 0. So obviously it would be nice to unlock the achievement. Let's assume that access to 10 to the power of 26 watts is desirable. Are Dyson spheres the way to go? The plausibility of a solid sphere the size of a planetary orbit is not really in question. They are not plausible. The incredible stresses on a solar structure that size are vastly greater than could be sustained by any known or yet imagined material. Even if a super advanced material with enough strength was discovered, you'd need impossibly large quantities, much more than there is non-hydrogen or helium matter in all of the planets in the solar system. The sphere would not be habitable, having only a tiny gravitational pull at its surface, and that would be towards the sun. And finally, it would be hopelessly unstable. Any small bump would cause one side to fall into the sun. Some of these issues could be dealt with. But in the end, it's just not an efficient way to start your galactic empire. So do we ditch Dyson's original idea in our quest to reach type 2? Not so fast. It's not feasible to build a giant solar sphere. But collecting the entire output of our home star may still be the smart choice. In fact, we can get around all of the issues I just described with a simple adjustment. Instead of building a Dyson sphere, build a Dyson swarm, individual solar collectors that are only kilometers or less in diameter and each with its own independent stable orbit around the sun. Build enough of these, and you can read the entire sun in all directions, absorbing its entire energy output. The crazy thing about the Dyson swarm is that we could probably start building one in the not too distant future. In fact, we could get started on the first collector pretty much right away. The thing that makes it seem a crazy prospect is the sheer scope. We'd have to disassemble entire planets for the raw materials alone. But believe it or not, there is a plan. It was proposed by Stuart Armstrong, AI expert and futurist. The idea is to cannibalize the planet Mercury. And that's just to begin the swarm. Mercury is ideal, because it has a gigantic solid iron core, comprising over 40% of the planet's mass. Combine that with the abundant oxygen in its crust, and we can make hematite, a naturally occurring, highly reflective iron oxide that has been used for millennia as primitive mirrors. So each of the swarms collectors would then be a giant polished hematite mirror, perhaps a kilometer across, but as thin as tinfoil. It would reflect light into a small solar power plant that would then beam energy somewhere useful, perhaps with a laser or a maser. The other nice thing about Mercury is that its gravity is low enough that launching mined raw material into space for construction is pretty efficient. Building the first collector would be the slowest. We start with limited mining, space launch, and orbital construction facilities, all of it autonomous. Energy supply is the big limiting factor at the start, so it takes about 10 years to build the first collector. But once it's complete, we have orders of magnitude more available power. We use it to power replicator robots, building new mining and manufacturing facilities, as well as replicatable replicators. It's an exponential process. Every new collector increases the energy available to build more collectors. Within 70 years, we have a partial Dyson swarm, and Mercury is nothing more than a debris field. To fully encompass the sun, we'd probably need to devour Venus, Mars, and a good number of asteroids and outer solar system moons, too, assuming we want to leave Earth intact. Let's assume that. Sound over the top? It's totally nuts. But it's likely doable. Autonomy in manufacturing, mining, and transportation are all progressing exponentially. Engineers are in the serious planning phases for all sorts of space-based assembly projects, including 3D printing of giant telescope mirrors. Real companies are gearing up to do autonomous asteroid mining, perhaps within a couple of decades. And all of this is without considering nano robotics, which could change the game entirely. Frankly, there's no obvious deal breaker here. Once complete, the Dyson swarm would harvest a good fraction of the sun's energy, so trillions of times the current energy output of the planet. What we then do with that energy is another matter. But is the Dyson swarm really the best path to type 2 status? Would other civilizations have gone that route, casting very conspicuous shadows on their home stars for us to detect? The advantage of using sunlight is that the sun is already making it. However, in terms of power efficiency, it's not all that great. Only 0.7% of the rest mass of the ingoing hydrogen fuel at the sun's core is converted to energy. Also, we need a mega structure to harvest it, with a raw material requirement close to that of all the terrestrial planets in the solar system. Is there a better way? Maybe. What if instead of converting 0.7% of fuel rest mass into energy we could achieve 100% efficiency? Anti-matter engines do this. But currently it takes more energy to create the anti-matter fuel than we get back out. Perhaps we can do better there, but there are also other options, for example, black hole engines. Energy can be harvested from a black hole, either from the Hawking radiation, from heat generated from infalling material, or by extracting angular momentum from the black hole's spin. We talked about one example, the Kugelblitz, in our previous episode on possible starship engines. The show "Space" also did a great episode on the Kugelblitz. Tapping the Hawking radiation from an artificial black hole is appealing, because once formed, we could perhaps sustain it from evaporation by feeding it with new matter. This is really 100% efficient conversion of mass into energy, assuming we can find a way to pump new matter into the proton-sized Kugelblitz against the tide of Hawking radiation. And we only need 1 billion Kugelblitzes to equal the sun's output. That's nothing, compared to the hundreds of quadrillion solar collectors in a full Dyson swarm. Added benefits. We get to keep Venus and Mars. And also Kugelblitz and other 100% efficient mass converters are indefinitely scalable. The Dyson sphere/swarm can absorb at most the entire energy output of the sun. However, there's enough mass in the solar system to run a type 3 civilization's Kugelblitz swarm for many times the current age of the universe. Of course, the trick is making the black holes in the first place. To make an industry standard, 600 million kilogram Kugelblitz, it takes something like 10% of the sun's energy output each second, focused into a single attometer at a single instant. But wait. That's the power we get from even a partial Dyson swarm. So there's something to do with the swarm's energy. Burn through Mercury. Then use that partial Dyson swarm's energy to build Kugelblitzes, in orbit, say, around Jupiter. Type 3, here we come. Maybe this is why we don't see Dyson swarms all through the galaxy. Aliens build partial swarms to provide the energy to build more efficient engines, which would be essentially undetectable. Or they try building their first Kugelblitz, and it goes very, very badly. Either way, Fermi paradox solved. Admittedly, the fading that the Kepler Space Telescope observed in Tabby's star is sort of consistent with a partial swarm. I guess it couldn't hurt to point some radio telescopes, to look for power leakage from the Kugelblitz swarm. But no. It's never aliens, unless every other explanation is exhausted. And we don't go in for that hokey stuff here on "Space Time." Thanks to "The Great Courses plus" for sponsoring this episode. "The Great Courses plus" is a service that allows you to learn about a range of topics from Ivy League professors and other educators from around the world. Go to thegreatcoursesp lus.com/spacetime and get access to a library of different video lectures about science, math, history, literature, or even how to cook, play chess, or become a photographer. New subjects, lectures, and professors are added every month. I learned a ton about energy production and use from Professor Wysession. With "The Great Courses plus," you can watch as many different lectures as you want, any time, anywhere, without any tests or exams. Help support the series and start your one month trial, by clicking the link below or going to thegreatcoursesp lus.com/spacetime. Hey guys, quick announcement. We'll be taking a break week next week while I travel and then coming back the following week with the answer to the quantum eraser lottery challenge and some intriguing physics news. Also, I'm planning to head to Austin for South by Southwest in September, to do a panel that we're calling "We Are All Scientists." It will be with Joe Hanson, from "It's OK To Be Smart" and Katie Mack, astrophysicist and cosmic genius. But first, I want to ask you guys to head to the South by Southwest panel picker page, link in the description. You just need to make a quick account and vote for our panel, please and thank you very much. A couple of weeks ago, we talked about the mysterious delayed choice quantum eraser. There was some heated discussion. A few of you pointed out that an important bit of info was emitted from the description. Now, we did this because we wanted to expand on that point through last week's challenge question. Now that we've done that, we can talk a bit more about it. The point is that in order to resolve the photon distributions at the screen, you need to know which detector was triggered by every one of those photon's entangled twins. This is done with coincidence electronics. If we see exactly the right time offset between a hit on the screen and a hit at one of the detectors, that means that those two photons were an entangled pair. After the experiment is done, we can pick out off the screen all of the photons that had twins hitting, say, detector A. Those photons turn out to show no interference pattern. But the photons associated with C or D do have an interference pattern. However, there is no way to figure out which photons correspond to which detectors until the arrival times at the screen are compared to the arrival times at the other detectors. And that information has to be sent at regular, slower-than-light speeds. In a way, this is even more crazy. Those locations are recorded on the screen, and the interference patterns are embedded in them. Those interference patterns hold information about future events. But we can't extract that information until those future events have occurred, and we can compare notes between the screen and detectors. We'll go into all of this in more detail in the challenge question answer and also when we come back to quantum entanglement. On a related note, David Stagg would like to know what the interference screen looks like before you know what the data is at detectors A, B, C, and D. Well, the screen just looks like a blur of photons. You see, it's not just that the blur of photons connected to detectors A and B are overlaid with an interference pattern from C and D, no. Even C and D produce a blur until you compare coincidence data. As I mentioned in the challenge question, the interference pattern of C has the opposite phase to that of D. Its peaks line up with D's valleys and vice versa. It's like adding a sign in a cosine wave. It adds up to a flat distribution, and it's only when you look at the photons connected to C and D separately that you see the bands. Jose Iturria would like to bring up the topic of the Berenstain Bears. Good one. I actually got that.
Info
Channel: PBS Space Time
Views: 2,457,886
Rating: 4.8733034 out of 5
Keywords: space time, pbs space time, pbs digital studios, pbs, astrophysics, physics, matt o'dowd, freeman dyson, dyson sphere, dyson swarm, blackhole, energy, kugelblitz, type II civilization, mercury, asteroid mining, nano robotics, antimatter, hawking radiation, engine, futurism, futurist, kepler, partial eclipse, black hole
Id: jW55cViXu6s
Channel Id: undefined
Length: 14min 30sec (870 seconds)
Published: Wed Aug 24 2016
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