Background temperature is 2.7 Kelvin At 4.7 Kelvin, a black body will give off 2.8e-5 W/m^2. We need to subtract the radiance of 2.7 Kelvin, which is 3.0e-6 W/m^2, resulting in 2.5e-5 W/m^2 The Sun produces about 3.9e26 W To radiate that much energy, you need 1.6e31 m^2 A sphere with that surface area would have a radius of 1.1e15 m, or 7500 AU. Voyager 1 is currently at 164 AU. However, looking cold isn't the only option. The energy could be directed in "safe" directions as a highly focused beam.
Yep, I agree with this answer. It's a relatively simple application of the Stefan-Boltzmann law for a hot object radiating into a colder environment: q = εσ(Th⁴ - Tc⁴)A where q is the energy output of the Sun, ε=1 is the emissivity coefficient of a black body, σ = 5.6703e-8 is the Stefan-Boltzmann constant, Th and Tc are the hot and cold temperatures (in Kelvin) and A is the surface area. Solve for A.
@@GunnerKhilasnikov A university level course on thermodynamics (which includes black body radiation) (e.g., as part of a BSc/MSc in Physics) should cover it. Short of taking such a course, you ought to be able to find textbooks covering it at a local library or in other online resources (the relevant keywords are "thermodynamics" and "black body radiation").
When talking about light pollution, I wish you would have also included that the amount of light we put out disrupts the natural world. Light pollution is wiping out insects and birds, which we will feel the effects of in the very near future
I love the Space Nuts podcast too, and Fred is a true advocate for light pollution. What with light, and now radio, i find it very annoying that Starlink can just plant as many as they want, and there will be many 1000s more. 🥺
It gets worse, Starlink is just one of the constellation projects, and there is no effective control of who/how large/how many satellites are going up.
Heres my mathing for the homework question: The Stefan-Boltzmann law says the total emissive power (measured in Watts per square meter) of a blackbody is E = σT⁴ where T is the blackbody's absolute temperature (in °K) and σ is the Stefan-Boltzmann constant (~5.67×10^-8). So, for T=4°K, E≈1.45×10^-5 W/m² At Earth's orbit (at 1 Astronomical Unit, or 1 AU, from the Sun), the solar energy flux (a.k.a. the "solar constant") is measured to be ~1361.5 W/m² To achieve the desired (4°K) level of energy flux, we'd therefore need to spread the energy out over the surface area of a sphere that is 1361.5 / 1.45×10^-5 larger than the sphere at 1 AU. That's a factor of ~9.39×10^7 greater surface area. Now, the area of a sphere goes as the square of radius. Therefore, we would need to enclose the Sun in a sphere with a radius of √(9.39×10^7) = 9690 AU. Or, about 0.153 light-years in radius. That's a pretty chonky sphere... 😅 Note: why am I treating this as straightforward energy flux attenuation with distance, when the question was about waste heat? Well, that's because energy cannot be created or destroyed - only transformed (i.e. the system must obey the law of energy conservation). Therefore, in the end, under an assumption of equilibrium conditions, the sum total of waste heat coming out has to equal the sum total of the energy input going in (i.e. the sum total of the energy coming off the Sun.)
Crysis has such a bad rap. I played Crysis 3 on a by then 5-year-old Phenom II x4 955BE + Radeon HD4850 1GB with FPS in the lower 40s at 1440x900 resolution on high graphics settings.
That rock on Mars looks like a nice piece of Gneiss. I only remember that because my science teacher in 8th grade told everyone to bring in a rock and he kept telling me I have a “nice rock” while I furiously kept asking what kind of rock it was. Great memory. So cool to see something that looks so similar to what I had in my hand at that time. Core memory. Super cool.
Congratulation to you for encouraging the Chinese scientists to be more transparent and not to be afraid of failure👍👍👍. I remembered telling my disappointed and miserable son to write the project's report on his failed science project, detailing the experiment, steps and where he thought the failure(s) were. He was astounded to learn he got the highest mark in his grade for the failed project!. He went on to be a successful young man, occasionally find time to mentor the younger students.
Can we please get an interview with anyone that can really get into the details of supernova impacting evolution because that sounds amazing. Great as always!
Saw it for the first time myself in my 50s, it's gorgeous. Get yourself out into the countryside on a clear night, it's worth the effort! I saw it during the month of February in the UK and it was high up in the sky, spreading right across 😊
If you ever have the chance for a trip to La Palma / Canary Islands, then you should go around (late) summer and around a new moon. The milky way there is absolutely stunning and no site in middle Europe compares to that spectacular view. Not even the Alps.
@@swissbiggy I just completed a 13-day trip through oars at the bottom of the Grand canyon and I got to see the Milky Way every night and shooting stars I started going to sleep with my glasses on
I am 67 and just finished a 13-day trip at the bottom of the Grand canyon on Dories... Blessed to see the Milky Way every night and shooting stars. I started sleeping with my glasses on so when I woke I could see the sky, so blessed.
Regarding Deep Blue Aerospace; "Dear DBA. Space Is Hard. We all should know this by now. Good to know you're busy being amazing despite how hard space (and especially space flight!) is. Being transparent helps other nations to decide if they can trust you and your hardware to carry their precious, sometimes even irreplaceable, gear into space. If future tests don't end well...may they at least end 'enlighteningly'. Rocketry is complicated work, as are auto-landing systems, and combining both is SURELY hard to manage. Seems like you have a good start on things so far. Good luck with future tests! If bad luck happens...well, I'm sure we'll all want to see any more amazing footage you record of the incident, and we'll keep rooting for you!" Not that they'll read this, but who knows! But yeah...space is HARD work! I hope they keep at it. Competition is almost always good.
Making videos of the starlinks a little bit recently.. I'm going to make some more because I've noticed that they're super easy to see, even in the middle of Ottawa.. It's kind of incredible 😮
@15:20 Dyson Sphere question, rather than make it so huge i would try and pump the heat to IR lasers and beam it away in such a manner to make it look like an Infrared Pulsar. Rather than hiding through invisibility, its hiding through deception. My thoughts on making something so large that it would 'radiate' at background temps or absolute zero is.. 1) wouldn't far off observers wonder why there were no stars in a region (as the invisible Dyson would obstruct those behind it from the observers point of view.) 2) If we can see the light and feel the heat from even the most distant stars, an attempt to shield one star and hide it from the rest of the universe would require a structure so large as to encompass many stars in our region .. which would again require an even larger structure to account for their additional heat... it seems this would end up much larger than the observable universe.
Dyson Sphere Question. Your not so stealthy Dyson Sphere would have to have a diameter roughly equal to the Oort Cloud in order to give off an infrared signature of only a few degrees above absolute zero. An object that size would be noticeable by stellar occultations of nearby stars. There also might be a few technical challenges in it's construction.
Possible Dyson spheres would require huge amounts of resources to construct. It is very likely that an advanced civilization would master other types of alternative and more efficient energy production.
Exactly! Dyson spheres never made sense to me. Not only the construction is unrealistic, also energy transfer is a problem... They're just sci-fi wet dream. There must be more efficient ways to produce / collect energy
If the goal is just energy collection, you might only need the mass of a decent sized asteroid to place some sort of energy collecting film around the entire sun at a distance of one AU. Just compare all the mass of a solar power collector on earth that is just structural support or to keep it facing the sun. And you don't need to start with any massive scale. You just have some energy collecting surface around whatever in-space activity you are engaged in, just like the ISS today. Right now we don't have anything as cheap or efficient. Even if we had fusion power, It would probably be heavy and labour intensive to maintain. It needs fuel and parts to be shipped to it, and in space _it still needs large radiating surfaces._ Fusion power (that is not the cheap and easily available solar power) will probably only be useful when the goal is to function far from the sun, eg out past Jupiter.
I would understand building a Dyson swarm, because that takes up less resources and heat and light from the sun (or other star) would still reach earth (or other planet) A Dyson sphere would make the entire star system inhabitable, which would also make transferring the energy even harder because now you have to send it to a different star system light years away.
Steve Bowers, Winchell Chung and Isaac Arthur play with Dyson swarms and thermal management a lot. Here's the thing: if you have a thermal differential, you have the ability to harness work, so you WANT to get down to those colder temps. The number I've always seen bounced around with Matrioshka brains is somewhere around seven layers thick. There's all sorts of ways to increase your surface area, it'll just depend on the resources at hand.
Couldn’t we just put some directional radiators on our Dyson sphere so we can point all of the infrared heat in one direction, to an empty spot in the sky where there’s no aliens to see the infrared beam?
That's called a Shkadov thruster, and not entirely but it makes the job much easier. You would still leak some omnidirectional IR radiation but you absolutely could minimize it, and keep the beam pretty narrow. You'd have to know where all the aliens were already to purposefully hide it, because there's no 'perfect' beam columnation - the beam will spread out slowly no matter what. But you could still do very good, less than an arcminute in the limit covering only 1 part in a million of the sky and hiding from the other 999,999 parts. Though it's called a thruster for a reason - the photon pressure generated would push the dyson sphere, and through gravitational coupling, the star. You'd move your star very slowly, but it would happen. Over millions of years, you'd get up to interstellar speeds, and over hundreds of millions, you'd get to low percentage points of light speed. So you would have to eventually take that into account.
Yeah that should work, actually. But it would generate a lot of waste energy due to thermodynamics (So you'd be emitting more energy on those beams then you would just from passively radiating heat. The tradeoff depends on how efficient they need to be vs. how worried they are about the dark forest hypothesis
About the gravitational coupling: Unless you mean something I do not understand, the Dydon sphere's gravity has no effect on the star because it is inside the sphere. In any sphere, only the part which is closer to the center than you has an effect because anythind farther cancels itself out. Therefore the sphere would propel itself until it crashes into the star. As someone else here said, we would need to throw a beam of energy back into the star to move it with us. But the sun consists of 99.8% of all the mass in the solar system. To accelerate it at the same rate as the sphere we woult need to feed it with 99.8% of the energy we would want to radiate off. (Assuming we consumed all the mass of the planets qnd everything else to build the sphere) So as we feed almost all the energy back into the system, the system naturally heats up proportional to the energy percentage fed back into the system. This means when the sun finds it's new equilibrium it radiates 50000% times what it does now so that the 0.2% thrown into the space equal the actual energy production. (Left out are eventual changes in the energy production due to the massively increased temperature in the star) The massively increased heat means the inner planets ate absolutely toast. Even Uranus would still recieve about 1.5 times the power per area than earth recieves now. Luckily we used the planets to build the sphere as the wouldn't be any use to us anymore anyways. Edit: Also, while we avoid being seen by most of the universe, the small part that we do sadiate into would have iz very obvious as the signal is so much stronger with a focused beam. And of course nobody will find it suspect if zhe sun just stops radiating in their direction.
Question: Assuming a distant galactic cluster is currently providing a gravitational lens, considering our solar system's motion orbiting the Milky Way, how long will a gravitational lensing alignment last before it either improves or degrades?
THAT is a fun question! It will be interesting for people living 100 years from now to make some concrete assessment of how our movement has changed our view through these gravitational lenses. It might even be detectable! The far background (lensed) galaxies might be about 1000 light years across. The Sun within our galaxy is moving about a lightyear every thousand years, but our galaxy is also moving. For some gravitational lenses in the sky we'd be going in the right direction to be moving one lightyear every 250 years across the focal plane of the gravitational lens.
For these purposes assume the lensing cluster is 5 billion light years away, and the background galaxy is 8 billion light years. Those values are probably within a factor of two of the real values for most lensing clusters.
Regarding the Dyson sphere, if you want to emit as little heat as possible I think the first step would be star lifting material from the star to make it burn cooler. That also increases the life span of the star.
According to Stephan Boltzman law, the energy is dependent on T^4. The area of sphere surface goes proportional to R^2. So if R goes 4 times, the energy release goes 16 times, which is equivalent to the temperature going 2 times. So R change is a square of a T change. In the requested scene we want to drop the temperature of the Sun from 6000K to 4K by 1500. Thus we need a Dyson sphere 1500^2 times the Sun's radius.
My try at the Dyson Sphere homework: Assuming the temperature at earth's distance r_1 = 1AU is T_1 = 288K and our target temperature is T_2 = 2.88K (for easy numbers) I would calculate r_2 with the inverse square law. Starting with: T_1 / T_2 = r_2^2 / r_1^2 We get: r_2 = sqrt( (T_1 / T_2) * r_1^2 ) Plugging in the numbers: r_2 = sqrt( (288/2.88) * 1 ) = sqrt( 100 ) = 10AU So the invisible Dyson Sphere would have a size of roughly Saturn's orbit. That seems surprisingly small 🤔
Hey Fraser, if earth was close to one of these gravitational lenses, would we be able to see it? Or is it a phenomenon only seen through a telescope and or great distance?
I love how Chad started showing me all the words you say in ALLCAPS at the start of every video. I really appreciate it, because I'm too much of a stupid goddamn baby to understand my own ears. Thanks for your help, Chad! It's totally not completely insulting to your audience in every single way possible. I can hear. And deaf people have the closed captions on anyway. I guess they get to read it twice! Lucky them.
I don't understand how the top and bottom poles of a Dyson sphere would be prevented from falling into the star, as they have no orbital velocity to counter gravity. Better and more efficient to build safe portable fusion reactors and scale as needed. Trying to encompass a star just because it is there is massively inefficient.
? Obscuring a star's light is as simple as putting a _lot_ of satellites around it. Which would happen naturally as more space infrastructure is built. As for something a bit more coordinated, statites would solve the problem you brought up quite nicely.
Also stars are the extremely inneficient fusion reactors. You could engage in star-mining to get more material, make it more stable and lengthen it's life. I generally would recommend Isaac Arthur's channel for discussion of stuff like this.
@@Milan_Openfeint Did not know that. I have a huge backlog to watch but you will agree that the initial discussions of megastructures were on the level, yes?
My favorite solutions to Dyson black body radiation capture are 1) the captured radiation is released periodically using massive gamma ray lasers 2) the captured radiation is converted to mass and feed back into the star
Hey Fraser! I have a question for your question show: Why is it that my eye needs an eyepiece to observe the night sky but my camera doesn't? This might be a straightforward answer, but I'd like an answer nonetheless! Keep up the great work!
Is it possible to view parallax shifts in gravitational lenses by taking a photo half a year later, or are they way too far for us to notice a difference?
Dyson sphere candidates being HotDOGs make no sense to me. Dyson sphere candidates would be single stars in the Milky Way Galaxy, since we can't really detect single stars further away than that. HotDOGs are the core of far away Galaxies. I don't get how one could be mistaken for the other?
I can see the vandenberg starlink constellation about 56 minutes after launch just south of michigan state line ! When they are released and still in formation ! Its like clockwork !
The clip where the Chinese rocket was landing and exploding did so once it made contact with the landing pad, not just before making contact. That's because the landing struts were compressing and the pad pushing the engine up into itself right before erupting in a fireball.
How big would that be? Well beyond Pluto. Talking hundreds of AU, because even at pluto distance, the watts per square meter far exceeds the background radiation temperature. HUGE. But nobody told me there would be math, so . . . that's my answer. Hundreds of AU, without doing any calculation. That's pretty darn large. I wonder what that does to the structural stability of it? Do they get more or less stable as you make them larger?
About the Kardashev scale. Most people describe it as if we will first cover every inch of the earth with power collectors before collecting any off-earth power, and then have encompassed our entire sun in a dyson swarm before we are collecting any power around other stars. Obviously, by the time our civilisation is using energy equivalent to what falls on the earth, that energy will include a fraction that is not literally falling on earth. I expect it would be a high fraction, eg maybe solar panels are ubiquitous on earth but that still might only cover 10-20% of the surface, and by then 80-90% of our civilisations power is being used by in-space colonies. i.e. a Kardashev one civilisation is not a single saturated planet but already a very multiplanetary species.
So Fraser is basically saying near the end of this video all advanced civilizations do not last very long and can not sustain those civilizations without overheating their planets, or wipe themselves out through war, war is something humans have always done and are still doing - you only have to look at the news - or particularly nuclear war, which nearly happened in the Cold War and the danger of which is now at its greatest since the Cold War. That may be one answer to the Fermi paradox- advanced civilizations tend to wipe themselves out before they can be contacted, and it seems human civilization will go the same way.
Providing low latency satellite internet connection to parts of the world where either it's not possible to connect through other means or the alternatives are too slow/expensive. The advantages of Starlink satellites in terms of the services they provide and the life changing impact it is having for some people far exceeds any disadvantages due to light pollution.
@@MrAlRats Satellite internet has existed for decades, with not that many satellites being put out in orbit. What Starlink is doing isn't new, neither that well done. If you need that many satellite constellations to provide your service then it isn't that efficient, is it?
@@spellicup You have no idea how this works do you? The old satellite internet connections had to be very very very far away, in a geostationary orbit. What this leads to, is enormous latency and very little bandwidth. You clearly have never had to use this service, its complete garbage for today's internet usage. I believe the lowest geostationary orbit currently is 22,000 miles away from earth. The highest Starlink satellite is 382 miles away. The reason you have so many Starlink satellites in the sky is because they have to be moving at a very high rate of speed, so you need a lot so you don't lose coverage. Also for reference, 24,901 miles is the diameter of earth.
Hi Fraser, why NASA don't use Boston Dynamics Spot robot for lunar and Mars exploration? Is it because its electronics are not designed to deal with radiation?
@03:46 -- you mean acts as a lens for some further region of the universe. It's not a singular object which is more easily visible, it's a cone dictated by general relativity of the extant universe.
Consider that a civilization that would be advanced enough to be able to construct a Dyson sphere might also have the technology to convert waste heat back to shorter wavelengths, and make the sphere look more like a more common K type star.
Once starship is available for science packages, an array of Starlink (and others) connected next generation space telescopes will completely dominate optical astronomy. Designers are busy, exciting discoveries ahead. Can't wait for the far side of the moon radio telescopes.
Do you think we are moving to the next generation of observation beyond earth based systems? It seems putting more observatory systems in space with the collected data being downloaded by systems like StarLink would be more beneficial?
16:13 I could not build a toaster, let alone a giga mega structure in space. So my guess: I would have to make it at least twice the size of a pro version. And I would have to breed a few metric ton of pixies, so that we can cool my 3rd class space structure with pixie dust.
Is it a trick question...I don't think its possible to hide the heat..would it need to be released eventually to the surrounding space no matter how big the sphere?
if heat did no dissipate with distance we would all burn up from starlight. multiple swarms of satellites going far out into the solar system would each use the waste heat from the swarm below them until you end up with a very large final shell at very low temp waste heat. you could continue that out to the landauer limit where there isnt enough energy to flip a bit anymore.
I dont think you could hide a dyson sphere completely, you would need more energy to cool and operate it than the imprisoned star produces. Thermodynamics would not allow it in my mind, also a sphere or even ring would no longer be an orbital object?
I calculated that the radius of a sphere to radiate the sun's power at approx 10,000 AU (assume 4K vs 2K background). This is absolutely enormous, almost 10% of a parsec diameter. If you were trying to hide this would probably be a bad idea as it would block background stars from other observers, revealing something was there as background stars came in and out of view around it. Also a 1 atom thick sheet at this size would have a mass of about 10^25 kg, a theoretical lower bound. That's about two Earths worth of mass.
Just had a crazy idea for reusing the ISS. Instead of de-orbiting this future UNESCO site, use its mass for probe launches. Attach a long tube to it, put a planetary probe in the tube (in a disposable sabot) and fire it like a potato gun. I realize that this is not related to this week’s space bites, but I have a lousy memory and will forget before I write it down.
Homework Question - Answer I would say that the radius of the sphere would need to be 5 AU, to ensure that the sun isn't able to heat sphere to noticeable temps. I said 5 AU because this is roughly the orbital radius of Jupiter and it's about out near Jupiter where the sun loses its power to warm. Anything much closer than that is going to continue to accrue heat and thanks to the vacuum of space, is going to have significant problems dissipating said heat.
Clearly a very advanced human operation to create a Dyson sphere around the Sun would hire the Yeti company to build a thermal container around it to hide it from the prying eyes of the Universe. I mean, duh...
My work smells fishy to me but get a radius of 1.5642e+08 light years. I based it on energy of one kelvin, energy released by sun per second and surface area of a sphere to keep a constant temperature. I feel like I glossed over some issue but I don't know what. I'm pretty sure it would be impractically large though. So I think I'd work on emitting the heat in a particular direction and aim where it is unlikely anyone is around to notice. Maybe get rid of the low hanging hot fruit with a laser or other energy beam. Get rid of some more with radiators aimed the same way. And then JWST wrap the rest of the "sphere."
@@JamesCairneyShhh, city dwellers think everything outside the city is nothing but wasteland and hillbillies. Don't let them know life is better outside the city.
Even if a sphere were large enough that the Sun's power was converted to thermal radiation that matched the background temp of the universe, it would appear hotter than that. It would also be absorbing (and the reradiating) or reflecting the CMB
I can imagine a partial structure maybe but circling an entire star? IMO, that's like creating a giant massive grenade! Besides technology advances so fast, you finish one area then another and the first area finished becomes obsolete. Impractical.
@@electroflame6188 Still seems impractical. Too much can go wrong. If such a good idea, why not do it with our own sun? Cain mentioned something about running huge "AI" computers. AI will eventually cause the human brain to "atrophy", for lack of a better word. AI cannot think. Now there is talk of implanting chips in peoples brains connected to these computer data bases?? That's been on the news lately. Musk's and a few other idea. He is a menace.
I don't get how a Dyson sphere would hold itself together if it doesn't rotate. But then, the polar regions would collapse first. And that would turn it into a Dyson Ring.
The size wouldn't really matter other than the Dyson sphere shouldn't be much larger than a goodly sized star. What it would need though, is an outward "skin" that would convert high-energy infrared photons to either a higher or lower frequency to obfuscate the construction. Such materials are available and I'm thinking even of hybrid nanometer materials that would convert infrared to, for example, excited hydrogen-frequency level
You don't have to hide the heat from the dyson sphere, you could concentrate in a single point like a quasar, away from any near by solar systems and avoiding detection from the vast majority of foes. I call it a death star.
If you put radiators in parabolic reflectors at the poles of the sphere, you could drastically reduce detection without violating thermodynamics. At least you know what directions "they" could have come from. :)
I thought the best story of the week was Supernova and Earth life, but that wasn't a choice in the poll. :( How often have we seen videos from science communicators telling us that we can't get superpowers from gamma rays or other radioactive sources? But that was a story about how radioactive fallout from a supernova caused accelerated evolution. Isn't that where the X-Men came from? How could that story not be a choice? In protest, I am going to refuse to do the homework. I do have a question, though. If the laws of thermodynamics make it impossible to hide a Dyson sphere, how did the civilization that built the Dyson sphere that the Enterprise D found while responding to the distress signal from the USS Jenolan make it so hard to find? The Dyson Sphere didn't appear on the Enterprise sensors until they had dropped out of warp in response to the distress signal. Even then, the only thing picked up by their sensors until they were practically on top of it was the sphere's gravity, not infrared light. Explain that!
Nice living space makes way more sense to me then energy harvesting as a motivation for building a Dyson sphere. An advanced civilisation in a sci-fi novel series I like built a Dyson sphere from all the planets, asteroids, etc in their home system and trillions of them lived utopian lives on the inside.
Dyson sphere: rough calculation. If the average temperature of Earth is about 15°C, then a dyson sphere with a radius of 1AU will emit infrared radiation at that temperature - 15°C == 288K. Dividing distance, it seems that 288K / 120AU =2.8K, which adds up with the cosmic background radiation to about 5K. Now I'm sure I've stuffed something up, but as a rough estimate, 120AU seems about right - Pluto's about 40K give or take IIRC, and that's about 40AU. Of course, the material to make a dyson sphere or swarm at that distance would be even more ridiculous than one at 1Au - that only took every planet in the solar system; a sphere at 120AU would require a LOT more material.
Shouldn't there be an inverse-square involved? Starting with: T_1 / T_2 = r_2^2 / r_1^2 we get: r_2 = sqrt( (T_1 / T_2) * r_1^2 ) With 288K at 1AU and a target of 2.88K we get: r_2 = sqrt( (288/2.88) * 1 ) = sqrt( 100 ) = 10AU
Except at half temperature, you lose 1/16 power. Combined with the radius squared suggested by Snygg, you get 120^2=14400 AU, not far from "my correct" value of 7347 AU.
I don’t know what SpaceX’s angle is right now regarding the FAA, but they can show this video from China and say they don’t have time for delays now that China is catching up. If you want SpaceX to compete the FAA needs to balance risk vs reward.
QUESTION(s): if a Manhattan sized space ship, made of pure aluminum, cruising at half the speed of light, flew past our solar system just beyond the orbit of Pluto. What kind of instrument would we need to detect it, and when will we have one?
Just as an off-the-cuff guess, I'd say an object that small, at that distance, would not be detectable by any telescope we now have -- even if it were perfectly reflective. But if its fusion drive were on, that might change.
IMHO at half the speed of light it would produce a lot of heat hitting solar wind, but I'm not sure how to estimate how much. But then I don't think we perform sky surveys in IR.
6:20 Just wait till they crank up their 5G direct to cell phone sats. The satellites antennas that AST SpaceMobile are using for 5G are 40’ x 60’, so probably starlink 5G will probably be / are similar when sx can start launching the FULL SIZE SATELLITES.
I guess the point is to restrict the emissions to the regulated frequency bands as tightly as possible with limits on the leakage in extraneous bands. There are allocated frequencies that are supposed to be kept clear for astronomical observations but shielding on components that emit elsewhere is weight Starlink probably finds inconvenient.
@@WizardofoOZeAU It is more complicated than that. This will require massive front end filtering on radio astronomy antennas. Also all sorts of “out of band” emissions cause problems at radio astronomy antennas already. That is why most radio astronomy antennas are situated in “radio / cellular quiet zones”. Now these antennas are going to get “RF Radiation” rammed directly down their antenna boresight and side lobes.
@@Mentaculus42 True, target frequencies are just peak emission and always have "tails" not to mention unintentional leakage, and any attempt at filtering to compensate will inevitably impact the resolution with the addition of all this noise. It is unfortunate that optic fibre rollout has been too slow worldwide as it had been thought it would cause a general decrease in the need for orbital communications platforms. Annoying that the need for say a moonbased system should it eventuate will inevitably add to SpaceX profits, seeing as they exacerbated the problem.
It is very pessimistic to imagine that humanity is just incapable of sobriety and will burn itself to death with the mere heat generated by expending exponentially more energy. If this is the case, then we may reach a hard limit relatively soon, and that would be the end of us.
I prefer the ring style of artificial living structure to those like a Dyson Sphere. I understand the need for an atmosphere but I like to think it can be done we just haven't figured out how to yet. With enough mass it should be possible in whichever orbit around whichever class star makes the math work for only a ring to function. I have never been too fond of the Sphere structure because it is too permanent. If your civilization is advanced enough to capture an entire star in a shell, why not just do that to capture energy and live on a planet somewhere else? It's obviously going to get very hot and very irradiated, quite quickly. I'll put it this way, would you rather focus on creating a force field, or radiation shielding and do you want to make the distinction at all?
How can an object that only shows up as infrared be a known object and also have a known ratio in the universe? How do you know that HotDOGs occur 1 in 3000 Quasars, or that they even exist? I'm confused at your certainty.
![[LIVE] BABYMONSTER(베이비몬스터) - DRIP | 두시탈출 컬투쇼](http://i.ytimg.com/vi/UG05pxLGwzc/mqdefault.jpg)
Background temperature is 2.7 Kelvin
At 4.7 Kelvin, a black body will give off 2.8e-5 W/m^2.
We need to subtract the radiance of 2.7 Kelvin, which is 3.0e-6 W/m^2, resulting in 2.5e-5 W/m^2
The Sun produces about 3.9e26 W
To radiate that much energy, you need 1.6e31 m^2
A sphere with that surface area would have a radius of 1.1e15 m, or 7500 AU.
Voyager 1 is currently at 164 AU.
However, looking cold isn't the only option. The energy could be directed in "safe" directions as a highly focused beam.
So much work, all seems correct, and all you get is a like LOL.
Yep, I agree with this answer.
It's a relatively simple application of the Stefan-Boltzmann law for a hot object radiating into a colder environment: q = εσ(Th⁴ - Tc⁴)A where q is the energy output of the Sun, ε=1 is the emissivity coefficient of a black body, σ = 5.6703e-8 is the Stefan-Boltzmann constant, Th and Tc are the hot and cold temperatures (in Kelvin) and A is the surface area. Solve for A.
Sorry for asking question
Where can I get this topic in physics?
To learn this things
@@GunnerKhilasnikov A university level course on thermodynamics (which includes black body radiation) (e.g., as part of a BSc/MSc in Physics) should cover it.
Short of taking such a course, you ought to be able to find textbooks covering it at a local library or in other online resources (the relevant keywords are "thermodynamics" and "black body radiation").
@@GunnerKhilasnikov I just asked ChatGPT and got the same answer with a good explanation
When talking about light pollution, I wish you would have also included that the amount of light we put out disrupts the natural world. Light pollution is wiping out insects and birds, which we will feel the effects of in the very near future
But how are we going to become a mult-planetary species if Leon has to consider the impact his vanity projects have on the world??
Luckily some good semeritans have been disabling street lights by taking out the wires and recycling them!
Well I never really liked insects anyway
Surely you like having food though? @@Starchface
@@Starchface do you like eating?
I love the Space Nuts podcast too, and Fred is a true advocate for light pollution. What with light, and now radio, i find it very annoying that Starlink can just plant as many as they want, and there will be many 1000s more. 🥺
It gets worse, Starlink is just one of the constellation projects, and there is no effective control of who/how large/how many satellites are going up.
Heres my mathing for the homework question:
The Stefan-Boltzmann law says the total emissive power (measured in Watts per square meter) of a blackbody is E = σT⁴ where T is the blackbody's absolute temperature (in °K) and σ is the Stefan-Boltzmann constant (~5.67×10^-8).
So, for T=4°K, E≈1.45×10^-5 W/m²
At Earth's orbit (at 1 Astronomical Unit, or 1 AU, from the Sun), the solar energy flux (a.k.a. the "solar constant") is measured to be ~1361.5 W/m²
To achieve the desired (4°K) level of energy flux, we'd therefore need to spread the energy out over the surface area of a sphere that is 1361.5 / 1.45×10^-5 larger than the sphere at 1 AU. That's a factor of ~9.39×10^7 greater surface area. Now, the area of a sphere goes as the square of radius.
Therefore, we would need to enclose the Sun in a sphere with a radius of √(9.39×10^7) = 9690 AU. Or, about 0.153 light-years in radius.
That's a pretty chonky sphere... 😅
Note: why am I treating this as straightforward energy flux attenuation with distance, when the question was about waste heat? Well, that's because energy cannot be created or destroyed - only transformed (i.e. the system must obey the law of energy conservation). Therefore, in the end, under an assumption of equilibrium conditions, the sum total of waste heat coming out has to equal the sum total of the energy input going in (i.e. the sum total of the energy coming off the Sun.)
Yup, this was roughly the same answer I got. The Dyson sphere would be about 350 billion times larger volume than a 1 AU sphere.
I used different values: 2K above CMB which is 2.73K, and 3.83e26 W for power emitted by the Sun. The answer, as expected, is 42 light days.
"Running crisis 3" 😂😂😂
why did you spell it like that
Why not? 🤔
Barney, hold my beer.
Crysis has such a bad rap. I played Crysis 3 on a by then 5-year-old Phenom II x4 955BE + Radeon HD4850 1GB with FPS in the lower 40s at 1440x900 resolution on high graphics settings.
That rock on Mars looks like a nice piece of Gneiss. I only remember that because my science teacher in 8th grade told everyone to bring in a rock and he kept telling me I have a “nice rock” while I furiously kept asking what kind of rock it was. Great memory. So cool to see something that looks so similar to what I had in my hand at that time. Core memory. Super cool.
Congratulation to you for encouraging the Chinese scientists to be more transparent and not to be afraid of failure👍👍👍.
I remembered telling my disappointed and miserable son to write the project's report on his failed science project, detailing the experiment, steps and where he thought the failure(s) were. He was astounded to learn he got the highest mark in his grade for the failed project!.
He went on to be a successful young man, occasionally find time to mentor the younger students.
Can we please get an interview with anyone that can really get into the details of supernova impacting evolution because that sounds amazing. Great as always!
Crysis 3 running on just one Dyson sphere sounds reasonable to me!
Minecraft.
Imagine a Beowulf cluster of these Dyson spheres
Almost 50 years old/young and living in the Netherlands.... never seen the milkyway in my entire life...
Prior to human technology, everyone everywhere could see it anywhere it was visible in the sky...our machines have a down side.
Saw it for the first time myself in my 50s, it's gorgeous. Get yourself out into the countryside on a clear night, it's worth the effort! I saw it during the month of February in the UK and it was high up in the sky, spreading right across 😊
If you ever have the chance for a trip to La Palma / Canary Islands, then you should go around (late) summer and around a new moon. The milky way there is absolutely stunning and no site in middle Europe compares to that spectacular view. Not even the Alps.
@@swissbiggy I just completed a 13-day trip through oars at the bottom of the Grand canyon and I got to see the Milky Way every night and shooting stars I started going to sleep with my glasses on
I am 67 and just finished a 13-day trip at the bottom of the Grand canyon on Dories... Blessed to see the Milky Way every night and shooting stars. I started sleeping with my glasses on so when I woke I could see the sky, so blessed.
That rocket almost landing looked absolutely amazing, I hope they continue posting both failures and successes.
Looks like AI.
It is hard to tell these days.
Thanks for all the news, Fraser! 😊
Stay safe there with your family! 🖖😊
You're welcome?
Regarding Deep Blue Aerospace; "Dear DBA. Space Is Hard. We all should know this by now. Good to know you're busy being amazing despite how hard space (and especially space flight!) is. Being transparent helps other nations to decide if they can trust you and your hardware to carry their precious, sometimes even irreplaceable, gear into space. If future tests don't end well...may they at least end 'enlighteningly'. Rocketry is complicated work, as are auto-landing systems, and combining both is SURELY hard to manage. Seems like you have a good start on things so far. Good luck with future tests! If bad luck happens...well, I'm sure we'll all want to see any more amazing footage you record of the incident, and we'll keep rooting for you!"
Not that they'll read this, but who knows! But yeah...space is HARD work! I hope they keep at it. Competition is almost always good.
Making videos of the starlinks a little bit recently.. I'm going to make some more because I've noticed that they're super easy to see, even in the middle of Ottawa.. It's kind of incredible 😮
@15:20 Dyson Sphere question, rather than make it so huge i would try and pump the heat to IR lasers and beam it away in such a manner to make it look like an Infrared Pulsar.
Rather than hiding through invisibility, its hiding through deception.
My thoughts on making something so large that it would 'radiate' at background temps or absolute zero is..
1) wouldn't far off observers wonder why there were no stars in a region (as the invisible Dyson would obstruct those behind it from the observers point of view.)
2) If we can see the light and feel the heat from even the most distant stars, an attempt to shield one star and hide it from the rest of the universe would require a structure so large as to encompass many stars in our region .. which would again require an even larger structure to account for their additional heat... it seems this would end up much larger than the observable universe.
Dyson Sphere Question. Your not so stealthy Dyson Sphere would have to have a diameter roughly equal to the Oort Cloud in order to give off an infrared signature of only a few degrees above absolute zero. An object that size would be noticeable by stellar occultations of nearby stars. There also might be a few technical challenges in it's construction.
Dyson spheres are a science fiction book 📕
Even Dyson was slightly tongue in cheek
@@aroemaliuged4776 "A few"...?! 🙂
"There also might be a few technical challenges in it's construction" To quote Deep Thought, "Tricky"
Next question: How thin would the wall of your Dyson sphere have to be to allow its construction from only material taken from the solar system?
Possible Dyson spheres would require huge amounts of resources to construct. It is very likely that an advanced civilization would master other types of alternative and more efficient energy production.
Exactly! Dyson spheres never made sense to me. Not only the construction is unrealistic, also energy transfer is a problem... They're just sci-fi wet dream. There must be more efficient ways to produce / collect energy
If the goal is just energy collection, you might only need the mass of a decent sized asteroid to place some sort of energy collecting film around the entire sun at a distance of one AU. Just compare all the mass of a solar power collector on earth that is just structural support or to keep it facing the sun.
And you don't need to start with any massive scale. You just have some energy collecting surface around whatever in-space activity you are engaged in, just like the ISS today.
Right now we don't have anything as cheap or efficient. Even if we had fusion power, It would probably be heavy and labour intensive to maintain. It needs fuel and parts to be shipped to it, and in space _it still needs large radiating surfaces._ Fusion power (that is not the cheap and easily available solar power) will probably only be useful when the goal is to function far from the sun, eg out past Jupiter.
Actually you can make Dyson spheres with zero resources
Nice assumption and transference of human needs to an alien being that you have NO IDEA how they think or what their needs are..
I would understand building a Dyson swarm, because that takes up less resources and heat and light from the sun (or other star) would still reach earth (or other planet)
A Dyson sphere would make the entire star system inhabitable, which would also make transferring the energy even harder because now you have to send it to a different star system light years away.
Steve Bowers, Winchell Chung and Isaac Arthur play with Dyson swarms and thermal management a lot.
Here's the thing: if you have a thermal differential, you have the ability to harness work, so you WANT to get down to those colder temps. The number I've always seen bounced around with Matrioshka brains is somewhere around seven layers thick. There's all sorts of ways to increase your surface area, it'll just depend on the resources at hand.
Couldn’t we just put some directional radiators on our Dyson sphere so we can point all of the infrared heat in one direction, to an empty spot in the sky where there’s no aliens to see the infrared beam?
That's called a Shkadov thruster, and not entirely but it makes the job much easier. You would still leak some omnidirectional IR radiation but you absolutely could minimize it, and keep the beam pretty narrow. You'd have to know where all the aliens were already to purposefully hide it, because there's no 'perfect' beam columnation - the beam will spread out slowly no matter what. But you could still do very good, less than an arcminute in the limit covering only 1 part in a million of the sky and hiding from the other 999,999 parts.
Though it's called a thruster for a reason - the photon pressure generated would push the dyson sphere, and through gravitational coupling, the star. You'd move your star very slowly, but it would happen. Over millions of years, you'd get up to interstellar speeds, and over hundreds of millions, you'd get to low percentage points of light speed. So you would have to eventually take that into account.
@@connorsniples4010 If you don't want to move your star, all you have to do, is making 2 beams in the opposite directions of each other
@@Kris_Lighthawk Yes, two beams that look as bright as a red dwarf (by adjusting the narrowness) to any aliens that can see it.
Yeah that should work, actually. But it would generate a lot of waste energy due to thermodynamics (So you'd be emitting more energy on those beams then you would just from passively radiating heat. The tradeoff depends on how efficient they need to be vs. how worried they are about the dark forest hypothesis
About the gravitational coupling:
Unless you mean something I do not understand, the Dydon sphere's gravity has no effect on the star because it is inside the sphere. In any sphere, only the part which is closer to the center than you has an effect because anythind farther cancels itself out. Therefore the sphere would propel itself until it crashes into the star.
As someone else here said, we would need to throw a beam of energy back into the star to move it with us.
But the sun consists of 99.8% of all the mass in the solar system. To accelerate it at the same rate as the sphere we woult need to feed it with 99.8% of the energy we would want to radiate off. (Assuming we consumed all the mass of the planets qnd everything else to build the sphere)
So as we feed almost all the energy back into the system, the system naturally heats up proportional to the energy percentage fed back into the system. This means when the sun finds it's new equilibrium it radiates 50000% times what it does now so that the 0.2% thrown into the space equal the actual energy production. (Left out are eventual changes in the energy production due to the massively increased temperature in the star)
The massively increased heat means the inner planets ate absolutely toast. Even Uranus would still recieve about 1.5 times the power per area than earth recieves now.
Luckily we used the planets to build the sphere as the wouldn't be any use to us anymore anyways.
Edit:
Also, while we avoid being seen by most of the universe, the small part that we do sadiate into would have iz very obvious as the signal is so much stronger with a focused beam. And of course nobody will find it suspect if zhe sun just stops radiating in their direction.
Dysonsphere homework; I'll say the size of the observable universe. Just to be sure it's undetectable.
Question: Assuming a distant galactic cluster is currently providing a gravitational lens, considering our solar system's motion orbiting the Milky Way, how long will a gravitational lensing alignment last before it either improves or degrades?
THAT is a fun question! It will be interesting for people living 100 years from now to make some concrete assessment of how our movement has changed our view through these gravitational lenses. It might even be detectable! The far background (lensed) galaxies might be about 1000 light years across. The Sun within our galaxy is moving about a lightyear every thousand years, but our galaxy is also moving. For some gravitational lenses in the sky we'd be going in the right direction to be moving one lightyear every 250 years across the focal plane of the gravitational lens.
It should be easy to calculate.
Missing a few variables: the relative motions of each item - Us, the gravitational lens, and the target; the and the distances involved for each.
For these purposes assume the lensing cluster is 5 billion light years away, and the background galaxy is 8 billion light years. Those values are probably within a factor of two of the real values for most lensing clusters.
Regarding the Dyson sphere, if you want to emit as little heat as possible I think the first step would be star lifting material from the star to make it burn cooler. That also increases the life span of the star.
Starlink cut back their transmissions when going over radio telescope locations.
Are you saying they do or they should?
He can't speak English properly. Forgive him.
I'd really like to hear about news about dwarf planets, these objects are criminally underrated
Go do your own research then?
@@strawberryfields5074 actually, iam
@@ILikeMyCheeseMoldyBru Good girl.
@@strawberryfields5074but im not a girl
@@ILikeMyCheeseMoldyBru Sorry. Good Boy 🐕
The single most amazing opener!!!
Giving life encouragement to adapt is a nice way of saying raining hell on Earth
According to Stephan Boltzman law, the energy is dependent on T^4.
The area of sphere surface goes proportional to R^2.
So if R goes 4 times, the energy release goes 16 times, which is equivalent to the temperature going 2 times.
So R change is a square of a T change.
In the requested scene we want to drop the temperature of the Sun from 6000K to 4K by 1500.
Thus we need a Dyson sphere 1500^2 times the Sun's radius.
My try at the Dyson Sphere homework:
Assuming the temperature at earth's distance r_1 = 1AU is T_1 = 288K and our target temperature is T_2 = 2.88K (for easy numbers) I would calculate r_2 with the inverse square law.
Starting with: T_1 / T_2 = r_2^2 / r_1^2
We get: r_2 = sqrt( (T_1 / T_2) * r_1^2 )
Plugging in the numbers: r_2 = sqrt( (288/2.88) * 1 ) = sqrt( 100 ) = 10AU
So the invisible Dyson Sphere would have a size of roughly Saturn's orbit.
That seems surprisingly small 🤔
Hey Fraser, if earth was close to one of these gravitational lenses, would we be able to see it? Or is it a phenomenon only seen through a telescope and or great distance?
I love how Chad started showing me all the words you say in ALLCAPS at the start of every video.
I really appreciate it, because I'm too much of a stupid goddamn baby to understand my own ears. Thanks for your help, Chad! It's totally not completely insulting to your audience in every single way possible.
I can hear. And deaf people have the closed captions on anyway. I guess they get to read it twice! Lucky them.
QUESTION: Can you please explain what a Schkadov Thruster is, and have we found any objects that match that description? Cheers
Mars Guy, an undersubscribed channel, has a good vid about that zebra rock.
Just saw a starlink strand yesterday, sept 27 2024. Looked pretty cool, wish i had my pro camera on me, which I put away just 20 minutes before!
I don't understand how the top and bottom poles of a Dyson sphere would be prevented from falling into the star, as they have no orbital velocity to counter gravity. Better and more efficient to build safe portable fusion reactors and scale as needed. Trying to encompass a star just because it is there is massively inefficient.
hmmmmm, right.
?
Obscuring a star's light is as simple as putting a _lot_ of satellites around it. Which would happen naturally as more space infrastructure is built.
As for something a bit more coordinated, statites would solve the problem you brought up quite nicely.
Also stars are the extremely inneficient fusion reactors. You could engage in star-mining to get more material, make it more stable and lengthen it's life.
I generally would recommend Isaac Arthur's channel for discussion of stuff like this.
@@yumazsterDid Isaac Arthur drift back to science? A few years ago he slowly started to ignore physics so I eventually unsubscribed.
@@Milan_Openfeint Did not know that. I have a huge backlog to watch but you will agree that the initial discussions of megastructures were on the level, yes?
My favorite solutions to Dyson black body radiation capture are
1) the captured radiation is released periodically using massive gamma ray lasers
2) the captured radiation is converted to mass and feed back into the star
Hey Fraser! I have a question for your question show: Why is it that my eye needs an eyepiece to observe the night sky but my camera doesn't? This might be a straightforward answer, but I'd like an answer nonetheless! Keep up the great work!
Is it possible to view parallax shifts in gravitational lenses by taking a photo half a year later, or are they way too far for us to notice a difference?
Honestly, thank you Deep-Blue aerospace for the amazing footage!
Lǎoshí shuō, gǎnxiè shēnlán háng tài tígōng de jīngcǎi jìngtóu!
Dyson sphere candidates being HotDOGs make no sense to me. Dyson sphere candidates would be single stars in the Milky Way Galaxy, since we can't really detect single stars further away than that. HotDOGs are the core of far away Galaxies. I don't get how one could be mistaken for the other?
We can absolutely detect individual stars in other galaxies. That's how we're able to calculate how far away they are, by looking at cephid variables
I can see the vandenberg starlink constellation about 56 minutes after launch just south of michigan state line ! When they are released and still in formation ! Its like clockwork !
The clip where the Chinese rocket was landing and exploding did so once it made contact with the landing pad, not just before making contact. That's because the landing struts were compressing and the pad pushing the engine up into itself right before erupting in a fireball.
Regarding the Dyson sphere question: Really big.
How big would that be? Well beyond Pluto. Talking hundreds of AU, because even at pluto distance, the watts per square meter far exceeds the background radiation temperature.
HUGE.
But nobody told me there would be math, so . . . that's my answer. Hundreds of AU, without doing any calculation. That's pretty darn large.
I wonder what that does to the structural stability of it? Do they get more or less stable as you make them larger?
About the Kardashev scale. Most people describe it as if we will first cover every inch of the earth with power collectors before collecting any off-earth power, and then have encompassed our entire sun in a dyson swarm before we are collecting any power around other stars.
Obviously, by the time our civilisation is using energy equivalent to what falls on the earth, that energy will include a fraction that is not literally falling on earth. I expect it would be a high fraction, eg maybe solar panels are ubiquitous on earth but that still might only cover 10-20% of the surface, and by then 80-90% of our civilisations power is being used by in-space colonies. i.e. a Kardashev one civilisation is not a single saturated planet but already a very multiplanetary species.
Just a reminder, 'Zebra Rock' is not an official Zebra (™) endorsed project, or by any ancilliary Zebra corporate entity.
The Dyson sphere should be the size of the Universw, just to be sure. 🙂
If a brown dwarf is very heavy, is a piece of it very heavy too? Or does it depend on the mass of the whole thing?
I’m going to say the Dyson Sphere needs to extend to the Kepler Belt to hide its heat.
So Fraser is basically saying near the end of this video all advanced civilizations do not last very long and can not sustain those civilizations without overheating their planets, or wipe themselves out through war, war is something humans have always done and are still doing - you only have to look at the news - or particularly nuclear war, which nearly happened in the Cold War and the danger of which is now at its greatest since the Cold War. That may be one answer to the Fermi paradox- advanced civilizations tend to wipe themselves out before they can be contacted, and it seems human civilization will go the same way.
Sorry if this is a stupid question, but what are the Starlink satellites meant to be doing?
Making more money for Space Karen.
@@stephencoppins9467 space internet, mostly
Providing low latency satellite internet connection to parts of the world where either it's not possible to connect through other means or the alternatives are too slow/expensive. The advantages of Starlink satellites in terms of the services they provide and the life changing impact it is having for some people far exceeds any disadvantages due to light pollution.
@@MrAlRats Satellite internet has existed for decades, with not that many satellites being put out in orbit. What Starlink is doing isn't new, neither that well done. If you need that many satellite constellations to provide your service then it isn't that efficient, is it?
@@spellicup You have no idea how this works do you?
The old satellite internet connections had to be very very very far away, in a geostationary orbit. What this leads to, is enormous latency and very little bandwidth. You clearly have never had to use this service, its complete garbage for today's internet usage.
I believe the lowest geostationary orbit currently is 22,000 miles away from earth. The highest Starlink satellite is 382 miles away. The reason you have so many Starlink satellites in the sky is because they have to be moving at a very high rate of speed, so you need a lot so you don't lose coverage.
Also for reference, 24,901 miles is the diameter of earth.
My first thought was to use a dust cloud to hide the dispersing heat. But don't know if that would really work.
Just because it's a hotdog doesn't mean it's not a Dyson sphere. at least we have a smaller pool to look for
Hi Fraser, why NASA don't use Boston Dynamics Spot robot for lunar and Mars exploration? Is it because its electronics are not designed to deal with radiation?
Spot uses too much power. It requires 400W and works only for 90 mins on one charge
@03:46 -- you mean acts as a lens for some further region of the universe. It's not a singular object which is more easily visible, it's a cone dictated by general relativity of the extant universe.
I imagine the Dyson Sphere would need to be close to the distance of the Oort Cloud in order to keep its outside ambient temperature ~4 kelvin.
Consider that a civilization that would be advanced enough to be able to construct a Dyson sphere might also have the technology to convert waste heat back to shorter wavelengths, and make the sphere look more like a more common K type star.
11:54 caught me off-guard
Once starship is available for science packages, an array of Starlink (and others) connected next generation space telescopes will completely dominate optical astronomy.
Designers are busy, exciting discoveries ahead. Can't wait for the far side of the moon radio telescopes.
Can we get a JWST true deep field from the repeated imaging of guide stars? What about from different surveys that overlap?
Heat is energy, all an advanced civilization needs is a way to convert it into useful energy. Maybe some like a thermoelectric generator (TEG)?
Do you think we are moving to the next generation of observation beyond earth based systems? It seems putting more observatory systems in space with the collected data being downloaded by systems like StarLink would be more beneficial?
Hi Fraser, did the Moon had a magnet field?
You don't need to dilute the heat energy. You can just focus it in a safe direction, e.g. the angular shapes of stealth aircraft.
Someone will see an extremely bright star
Solution is to move observatories out in space. Starship will help with that by making space travel much cheaper.
16:13 I could not build a toaster, let alone a giga mega structure in space. So my guess: I would have to make it at least twice the size of a pro version.
And I would have to breed a few metric ton of pixies, so that we can cool my 3rd class space structure with pixie dust.
Is it a trick question...I don't think its possible to hide the heat..would it need to be released eventually to the surrounding space no matter how big the sphere?
if heat did no dissipate with distance we would all burn up from starlight. multiple swarms of satellites going far out into the solar system would each use the waste heat from the swarm below them until you end up with a very large final shell at very low temp waste heat. you could continue that out to the landauer limit where there isnt enough energy to flip a bit anymore.
What about focusing the waste heat from a Dyson Swarm and aiming the exhaust away from any populated parts of the galaxy?
I always thought a black hole was like a bubble or lens. Ever watch stars get sucked into black holes and "burped" out years later.
I dont think you could hide a dyson sphere completely, you would need more energy to cool and operate it than the imprisoned star produces. Thermodynamics would not allow it in my mind, also a sphere or even ring would no longer be an orbital object?
I calculated that the radius of a sphere to radiate the sun's power at approx 10,000 AU (assume 4K vs 2K background).
This is absolutely enormous, almost 10% of a parsec diameter. If you were trying to hide this would probably be a bad idea as it would block background stars from other observers, revealing something was there as background stars came in and out of view around it.
Also a 1 atom thick sheet at this size would have a mass of about 10^25 kg, a theoretical lower bound. That's about two Earths worth of mass.
Just had a crazy idea for reusing the ISS. Instead of de-orbiting this future UNESCO site, use its mass for probe launches. Attach a long tube to it, put a planetary probe in the tube (in a disposable sabot) and fire it like a potato gun. I realize that this is not related to this week’s space bites, but I have a lousy memory and will forget before I write it down.
Homework Question - Answer
I would say that the radius of the sphere would need to be 5 AU, to ensure that the sun isn't able to heat sphere to noticeable temps. I said 5 AU because this is roughly the orbital radius of Jupiter and it's about out near Jupiter where the sun loses its power to warm. Anything much closer than that is going to continue to accrue heat and thanks to the vacuum of space, is going to have significant problems dissipating said heat.
Clearly a very advanced human operation to create a Dyson sphere around the Sun would hire the Yeti company to build a thermal container around it to hide it from the prying eyes of the Universe. I mean, duh...
There will never be enough mate, just like gathering wealth and knowledge. Hoarding is in our nature
9:02 The rock looks like dolomite and limestone.
My work smells fishy to me but get a radius of 1.5642e+08 light years. I based it on energy of one kelvin, energy released by sun per second and surface area of a sphere to keep a constant temperature. I feel like I glossed over some issue but I don't know what.
I'm pretty sure it would be impractically large though. So I think I'd work on emitting the heat in a particular direction and aim where it is unlikely anyone is around to notice. Maybe get rid of the low hanging hot fruit with a laser or other energy beam. Get rid of some more with radiators aimed the same way. And then JWST wrap the rest of the "sphere."
I've never actually seen a starlink.
You live in a city?
Nevermind the effects of light pollution on biodiversity
Most animals don't live in the city.
@@JamesCairneyShhh, city dwellers think everything outside the city is nothing but wasteland and hillbillies. Don't let them know life is better outside the city.
Even if a sphere were large enough that the Sun's power was converted to thermal radiation that matched the background temp of the universe, it would appear hotter than that. It would also be absorbing (and the reradiating) or reflecting the CMB
Earth-based astronomical observatories are relics.
Dyson spheres don't make a bit of sense to me, I'm sure there are more cost effective ways to harness or produce energy.
Wait until they start talking about Dyson spheres that encompass an entire galaxy. Now we are talking energy consumption.
@@Pat19997 I will not wait, no tky
I can imagine a partial structure maybe but circling an entire star? IMO, that's like creating a giant massive grenade! Besides technology advances so fast, you finish one area then another and the first area finished becomes obsolete. Impractical.
@@zsigzsagThat's because you're imagining it as a literal shell encompassing a star, rather than a lot of (relatively) small orbiting satellites.
@@electroflame6188 Still seems impractical. Too much can go wrong. If such a good idea, why not do it with our own sun? Cain mentioned something about running huge "AI" computers. AI will eventually cause the human brain to "atrophy", for lack of a better word. AI cannot think. Now there is talk of implanting chips in peoples brains connected to these computer data bases?? That's been on the news lately. Musk's and a few other idea. He is a menace.
Could we get someone to apply the reverse transformations needed to turn those lensed galaxies into their undistorted forms?
I don't get how a Dyson sphere would hold itself together if it doesn't rotate. But then, the polar regions would collapse first. And that would turn it into a Dyson Ring.
The size wouldn't really matter other than the Dyson sphere shouldn't be much larger than a goodly sized star. What it would need though, is an outward "skin" that would convert high-energy infrared photons to either a higher or lower frequency to obfuscate the construction. Such materials are available and I'm thinking even of hybrid nanometer materials that would convert infrared to, for example, excited hydrogen-frequency level
You don't have to hide the heat from the dyson sphere, you could concentrate in a single point like a quasar, away from any near by solar systems and avoiding detection from the vast majority of foes. I call it a death star.
Except for a few unlucky stars
So, Dyson sphere would essentially rob the outer solar system of starlight.
If you put radiators in parabolic reflectors at the poles of the sphere, you could drastically reduce detection without violating thermodynamics. At least you know what directions "they" could have come from. :)
I thought the best story of the week was Supernova and Earth life, but that wasn't a choice in the poll. :( How often have we seen videos from science communicators telling us that we can't get superpowers from gamma rays or other radioactive sources? But that was a story about how radioactive fallout from a supernova caused accelerated evolution. Isn't that where the X-Men came from? How could that story not be a choice? In protest, I am going to refuse to do the homework. I do have a question, though. If the laws of thermodynamics make it impossible to hide a Dyson sphere, how did the civilization that built the Dyson sphere that the Enterprise D found while responding to the distress signal from the USS Jenolan make it so hard to find? The Dyson Sphere didn't appear on the Enterprise sensors until they had dropped out of warp in response to the distress signal. Even then, the only thing picked up by their sensors until they were practically on top of it was the sphere's gravity, not infrared light. Explain that!
Nice living space makes way more sense to me then energy harvesting as a motivation for building a Dyson sphere. An advanced civilisation in a sci-fi novel series I like built a Dyson sphere from all the planets, asteroids, etc in their home system and trillions of them lived utopian lives on the inside.
Dyson sphere: rough calculation.
If the average temperature of Earth is about 15°C, then a dyson sphere with a radius of 1AU will emit infrared radiation at that temperature - 15°C == 288K.
Dividing distance, it seems that 288K / 120AU =2.8K, which adds up with the cosmic background radiation to about 5K.
Now I'm sure I've stuffed something up, but as a rough estimate, 120AU seems about right - Pluto's about 40K give or take IIRC, and that's about 40AU.
Of course, the material to make a dyson sphere or swarm at that distance would be even more ridiculous than one at 1Au - that only took every planet in the solar system; a sphere at 120AU would require a LOT more material.
Shouldn't there be an inverse-square involved?
Starting with: T_1 / T_2 = r_2^2 / r_1^2
we get: r_2 = sqrt( (T_1 / T_2) * r_1^2 )
With 288K at 1AU and a target of 2.88K we get: r_2 = sqrt( (288/2.88) * 1 ) = sqrt( 100 ) = 10AU
Except at half temperature, you lose 1/16 power. Combined with the radius squared suggested by Snygg, you get 120^2=14400 AU, not far from "my correct" value of 7347 AU.
I don’t know what SpaceX’s angle is right now regarding the FAA, but they can show this video from China and say they don’t have time for delays now that China is catching up. If you want SpaceX to compete the FAA needs to balance risk vs reward.
QUESTION(s): if a Manhattan sized space ship, made of pure aluminum, cruising at half the speed of light, flew past our solar system just beyond the orbit of Pluto. What kind of instrument would we need to detect it, and when will we have one?
Just as an off-the-cuff guess, I'd say an object that small, at that distance, would not be detectable by any telescope we now have -- even if it were perfectly reflective. But if its fusion drive were on, that might change.
IMHO at half the speed of light it would produce a lot of heat hitting solar wind, but I'm not sure how to estimate how much. But then I don't think we perform sky surveys in IR.
6:20 Just wait till they crank up their 5G direct to cell phone sats. The satellites antennas that AST SpaceMobile are using for 5G are 40’ x 60’, so probably starlink 5G will probably be / are similar when sx can start launching the FULL SIZE SATELLITES.
I guess the point is to restrict the emissions to the regulated frequency bands as tightly as possible with limits on the leakage in extraneous bands. There are allocated frequencies that are supposed to be kept clear for astronomical observations but shielding on components that emit elsewhere is weight Starlink probably finds inconvenient.
@@WizardofoOZeAU
It is more complicated than that. This will require massive front end filtering on radio astronomy antennas. Also all sorts of “out of band” emissions cause problems at radio astronomy antennas already. That is why most radio astronomy antennas are situated in “radio / cellular quiet zones”. Now these antennas are going to get “RF Radiation” rammed directly down their antenna boresight and side lobes.
@@Mentaculus42 True, target frequencies are just peak emission and always have "tails" not to mention unintentional leakage, and any attempt at filtering to compensate will inevitably impact the resolution with the addition of all this noise.
It is unfortunate that optic fibre rollout has been too slow worldwide as it had been thought it would cause a general decrease in the need for orbital communications platforms.
Annoying that the need for say a moonbased system should it eventuate will inevitably add to SpaceX profits, seeing as they exacerbated the problem.
I guess the radius of the Dyson Sphere radiating all the Sun's power needs to be around 0.2 light year to limit its temperature to 4 K
Dyson does make a mean dog.
It is very pessimistic to imagine that humanity is just incapable of sobriety and will burn itself to death with the mere heat generated by expending exponentially more energy. If this is the case, then we may reach a hard limit relatively soon, and that would be the end of us.
Who could have seen that one man's greed could compromise mankind's earthbound astronomy? 🙄
I prefer the ring style of artificial living structure to those like a Dyson Sphere. I understand the need for an atmosphere but I like to think it can be done we just haven't figured out how to yet. With enough mass it should be possible in whichever orbit around whichever class star makes the math work for only a ring to function. I have never been too fond of the Sphere structure because it is too permanent. If your civilization is advanced enough to capture an entire star in a shell, why not just do that to capture energy and live on a planet somewhere else? It's obviously going to get very hot and very irradiated, quite quickly.
I'll put it this way, would you rather focus on creating a force field, or radiation shielding and do you want to make the distinction at all?
How can an object that only shows up as infrared be a known object and also have a known ratio in the universe? How do you know that HotDOGs occur 1 in 3000 Quasars, or that they even exist? I'm confused at your certainty.
That Deep Blue drone footage looks very off - it's just too perfect and the sand whipped up doesn't look right