Randomness thread, part two.

[MadMojoMonkey]

You'd think, but geostationary orbits are a long way out. That inverse square law is going to be a right bastard at such a distance. In the technology's infancy, we'll be doing well to just get a few seconds of energy every time a low-orbit solar beam thingy passes overhead.

The inverse square law is for spherically expanding wave fronts. A space laser would be, as the name implies, a laser. Now, it is not the case that a laser is perfectly focused, but it's pretty darn good. The lack of perfect focus means... oops... the inverse square law comes back to bite us. However, the amount of spread of a laser beam is orders of magnitude lower than a spherical wave.

So yes, you'd deal with compromises with putting the station so far away, but not so bad as you might imagine. Also, if the station isn't geostationary, then you can only use it half the time. So it better have a bunch of expensive and heavy batteries up there to store that charge when you can't see it. Oof. But then... it is in the shadow of the Earth half the time.


So you'd want to do this in at least 2 stages. First a polar orbit that is always in line of sight of the sun so the panels are always working. Second, a relay station in geostationary orbit so that it's always above the ground-based energy collection plant.

[MadMojoMonkey]

Geostationary orbits only exist above the equator, too. That means that if you're beaming to a location that isn't on the equator, then it will inherently need to be done at an angle. The greater the latitude, the greater the angle, and a larger spread of energy. If we're going to beam light from space from geostationary solar generators, the only logical location for energy collectors is somewhere along the equator.

Things on Earth can be angled to point straight toward the geostationary satellite. The losses from the angle can be eliminated.

[MadMojoMonkey]

A light beam in geostationary orbit would need to be around 50000 times more concentrated a beam compared to one in very low orbit in order to have the same footprint on earth.

Inverse square law for the win.

How did you come to this conclusion? What were your inputs?

[OngBonga]

Good point about a laser not having the play by the inverse square rule.

Things on Earth can be angled to point straight toward the geostationary satellite. The losses from the angle can be eliminated.

I'd argue this probably isn't true. Even if we can angle the receiver perpendicular to the beam (also good point), there's still the problem of the atmosphere. This is why we have seasons, why it's colder in winter. The sun is actually closer to us in winter (in the Northern Hemisphere) but the angle it passes through the atmosphere is far from perpendicular, meaning more Rayleigh scattering (I think that's the one). Surely laser beams are just as subject to scattering as solar rays?

How did you come to this conclusion? What were your inputs?

Without googling the numbers again, it was N= (G/L)^2, where G is geostationary orbital altitude and L is Low earth orbit... with L value at the lowest possible orbit, N is around 50k. Where L is ISS altitude, N is approximately 20k.

But the ^2 function is obviously assuming inverse square law applies.

[OngBonga]

Maybe a laser can "burn" through the atmosphere, creating a near-vacuum channel, or at least a linear flow of plasma, minimising scattering.

Maybe we can theoretically eliminate losses and collect from nearly anywhere in the world.

[OngBonga]

Hmmm nah. Let's assume it creates a near-vacuum... this is ridiculously intense low pressure in the atmosphere and will result in a vortex of wind to circulate around the beam. We're basically creating the most intense tornado possible. Probably not good for the ground-based beam collector, regardless of its location.

And if we've got a stream of plasma hitting the beam collector, then it's going to need to be made of something pretty resilient.

I think it's science fiction.

[OngBonga]

Space-based solar power is likely to be the distant future of energy, but I'm not sure about beaming it back to Earth. I doubt we'd cause tornados, but plasma streams seem like a very real risk. A stream of ionised particles hitting solid material, even mega-reinforced pure fucking titanium made by Chuck Norris himself, is going to cause damage, meaning regular maintenance. Expensive as fuck.

With such an abundance of energy, getting into space and back won't be nearly as expensive. Seems like it will be much easier and cheaper to just charge batteries in space.

[OngBonga]

Alright, if you heat water using the beam, or some other liquid like an oil, and have near perfect insulation and heat recovery, then the plasma stream might not be a problem. We might be back in business here.

I should be working for some space agency thinktank.

[MadMojoMonkey]

Surely laser beams are just as subject to scattering as solar rays?

Scattering is dependent on an inverse 4th power law.
You think inverse square is devastating to doubling distance? Halving the wavelength (doubling the frequency) makes it 16x more likely to scatter. So I'd imagine we'd want to use the longest wavelength we could, which puts us in the infrared to radio range. A quick google search confirms proposals tend to favor using microwaves (between infrared and radio).

No plasma. Game ender. Too much energy you waste in creating the plasma / tornado / whatever. That energy comes from somewhere, and that somewhere is going to be your "payload."

Turns out a laser that powerful would be too expensive to build and put in place to be competitive with the cost of any ground-based solar network, anyway.
Parabolic dishes are what design proposals have put more time into. The spread of the wave isn't negligible, but not trivial to solve. A 1 km transmitter dish in orbit would need to be collected on the ground with a 10 km diameter receiving array.

[MadMojoMonkey]

If we can build the array somewhere besides Earth, then the cost to get it in place could be much reduced. That is a long-future project, though. It assumes we could have manufacturing on the Moon or otherwise outside of Earth's gravity and atmosphere.

Future economic pressures may change and the cost of space solar may become comparable to ground-based systems either due to increases in ground-based costs or reduction in space-based costs.

Right now, though... it doesn't seem economically viable, given other alternatives.

[OngBonga]

Right now, though... it doesn't seem economically viable, given other alternatives.

Economics isn't just about how much it costs now. It's how much it costs in the future too. The sooner we get up into space and doing this kind of thing, the faster we learn how to do it better. It does seem that humans are at a critical point where we really, really need to find a viable alternative to fossil fuels, without that meaning less net energy use. I feel like I'm being generous thinking we've got half a century to sort it out, before we either run out of oil or the climate crushes economies to the point where innovation becomes exponentially more difficult.

If we can do this with microwaves then that's great. It surprises me that we can use high-entropy light, but I guess there's still plenty of usable energy at low frequencies. And frankly I know fuck all about this kind of thing other than to throw the word "entropy" in to make it seem like I might get it a tiny little bit.

No plasma. Game ender. Too much energy you waste in creating the plasma.

Depends if you can recover that energy. Plasma could surely be used to heat up water, for example. Maybe an oil is better. If all that plasma is streaming down with the laser beam, it's carrying the energy to where we want it.

[MadMojoMonkey]

Microwaves are only good because we need to get through the atmosphere, and Rayleigh scattering off particles is proportional to the inverse 4th power of the wavelength.
In more digestible terms, we'd love to use higher energy photons, and send fewer of them, but much like the blue light from our sun, it would go everywhere. Worse, even. UV scatters so readily that it would be spread out everywhere and not at all being a nice "beam."

I mean... the sky is blue because white light from the sun hits the atmosphere and the blue gets spread all over the place more than the rest. Going even as short a wavelength as a blue laser would be bad for that reason.


You can't recover the energy from the plasma. It's problematic for many reasons. The big problem is there's nothing containing the plasma. It's hot and trying to rapidly expand. As it expands, the pressure drops, and at some point, it reaches equilibrium, except... there's nothing containing the plasma. It has momentum, it keeps expanding. Now it's too thin, and it collapses back. All the while the bonds broken that made it plasma are recombining outside the beam, and that emits X-rays, or worse, gamma radiation in all directions, which is real bad.

It's just ... all kinds of problematic. Kinda like you just decided to turn that part of the atmosphere into a constant explosion for fun, and while that is cool, it's not any kind of efficient way to transmit energy.

[OngBonga]

Inverse 4th power is nuts. I can't comprehend a geometric reason why this would be the case. Inverse square is geometrically logical, it's a mathematical description of an expanding sphere. But inverse 4th power? wtf is that? An expanding hyperhypersphere?

[OngBonga]

I guess knowing fundamentally what scattering is would be helpful. In layman's terms we think of it as light deflecting off particles. But that isn't really how light works. A photon hits a particle, excites an electron, that electron in turn emits a photon of a particular wavelength, that photon will then go and hit something else, which in turn means another excited electron spitting out another photon, and this happens trillion or quadrillions of times until photons hit your eyes, with blue wavelength photons being the most likely. Why is blue more likely? It's higher energy than lower colours, so maybe the cascade effect has only reached a certain point. Maybe if we had a different atmosphere, or a much larger atmosphere, the sky wouldn't be blue, it might be yellow by the time photons are reaching the surface.

idk but I don't think geometry is really all that helpful in thinking about this.

[OngBonga]

Ok so what if we send a very-high energy pulse of light first, to hopefully create a very brief vacuum channel through the atmosphere, then send the main beam through that channel before it collapses?

We can probably handle the tornado. It would be ridiculously intense but also very short lived, should be fine.

[MadMojoMonkey]

Inverse 4th power is nuts. I can't comprehend a geometric reason why this would be the case. Inverse square is geometrically logical, it's a mathematical description of an expanding sphere. But inverse 4th power? wtf is that? An expanding hyperhypersphere?

Photons are electromagnetic waves. The molecules are made of atoms, both are held together with electromagnetic interactions. Both will respond, re-orient themselves, absorb and re-emit electromagnetic waves, etc. when a wave passes over them.

The shorter the wavelength, the more dramatic the energy transfer to the molecules as it passes*. The molecules basically absorb and re-emit the incoming photon in a random direction. Then that scattered photon arrives at another molecule at the same time as some other photon, but they are not in phase. They interfere in a not coherent way. This increases the scattering interaction.

So it's not about a single expanding wave front, but about waves being ping-ponged around and interfering with each other.

Due to quantum mechanical reasons, the longer the wavelength, the less dramatically it interacts with the molecules. The molecules become tinier by comparison and the waves pass right around them without exchanging momentum, though acquiring some phase change.

*As the wavelength gets shorter and shorter, such that the ratio of wavelength to molecule size is getting close to 1:1, the inverse 4th power relents and inverse square is a better approximation to the behavior. But then, you're now in the energy region where you're stripping electrons off their molecules / atoms, and losing a lot of energy in the beam to kinetic energy.

[OngBonga]

...the inverse 4th power relents and inverse square is a better approximation to the behavior.

This is a rather dramatic transition. We've skipped a dimension! At some point in between, surely inverse cube is a better approximation. If not, does that mean there is an abrupt change from 4th to square?

[MadMojoMonkey]

Maybe if we had a different atmosphere, or a much larger atmosphere, the sky wouldn't be blue, it might be yellow by the time photons are reaching the surface.

Absolutely correct that the content and thickness of Earth's atmosphere gives our daytime sky it's cyan-blue color. If you're ever up on a tall mountain, the sky looks a deeper blue.

You can tell what our sky would look like if the atmosphere were thicker every sunrise and sunset. As the light from the sun is getting to you through such a shallow angle with the horizon, the light passes through more atmosphere before it reaches you, and has more distance through which to scatter.

Different chemical compositions of atmosphere can have different color properties. Different gasses are different colors. Nitrogen just happens to be mostly transparent to most visible light because our eyes evolved to be able to see in our atmosphere. I'd imagine eyes that evolved on Venus would be sensitive to wavelengths that they are exposed to. Though the scattering of blue light is a law, the color perception and wavelength sensitivity range of human eyes isn't even a norm among eyes on Earth.

[MadMojoMonkey]

This is a rather dramatic transition. We've skipped a dimension! At some point in between, surely inverse cube is a better approximation. If not, does that mean there is an abrupt change from 4th to square?

It's a smooth transition. It's not like the only behavior near the visible spectrum is the inverse 4th power. Just that the inverse 4th power is the dominant term in a polynomial expansion of a greater model.

But not all polynomials (or polynomial expansions) have a cubic term. Some functions are "even" meaning their polynomial expansions will only contain even number powers (which is a terrible way to define 'even' in this sense, but it is sufficient, I think). A better definition for an "even" function, y(x), is that it has mirror symmetry about the y-axis. An "odd" function has 180 degree rotational symmetry about the origin.

A better definition still is to say if y(x) = y(-x), then y is an even function. If -y(x) = y(-x), then y is an odd function.

E.g. cosine is an even function. Sine is an odd function. x is odd. x^2 is even. x^3 is odd. x^4 is even.

IF the function you are expanding into a polynomial approximation is itself even, any fucntional expansion will contain only even terms. And vise versa. IF the function is odd, its expansions will contain only odd terms.

If you note the polynomial expansion for sin and cos, you'll see the sin expansion has only terms with x, x^3, x^5, etc. and the cos expansion has only terms with x^0, x^2, x^4, etc.

But this is way off topic.

[oskar]

Yesterday I boiled 3 eggs. I swear on my life that I only ate two of them, yet the third one is nowhere to be found.

[oskar]

On second thought: I probably ate it.
Kamala can still become president, if she would just smother Biden with a pillow, but somehow nobody is even talking about that.

[OngBonga]

Any footage of blue haired feminists screaming at the sky this time?

Twitter is hilarious. People wondering why Dems got 15 million less votes than 2020. Not only are they refusing to consider that maybe it was the extra 15 million votes they got in 2020 that should be raising eyebrows, they're also forgetting that four years ago they were calling people "election deniers" and worse for asking similar questions.

[oskar]

Republicans literally just said "stop the steal" and democrats immediately stopped stealing... Just keep stealing, idiots!
And where's the foreign election interference for Dems? Khomeini and Xi really dropping the ball hard. Really sad performance.

I wonder if this will lead to any introspection for dems. They've done it twice now. The first time they learned nothing. My guess would be that what they're going to remember from this disaster is: don't run a woman, and blame progressives even harder.

[oskar]

Twitter is hilarious. People wondering why Dems got 15 million less votes than 2020.

Trump got a lot less votes as well. Low turnout election. Who can blame anyone?

[OngBonga]

Trump is down 3m votes compared to 15m for Dems, with lots of votes still to be counted towards popular vote tally. This is based on the info and graphs I'm seeing all over Twitter. Obviously I can't be fucked to fact check any of it, so as usual, take my comments with a few kilos of salt.

[oskar]

This will likely be the most scrutinized election in the history of the world, so I would rate the probability of large scale election fraud going unnoticed very low.

On a positive note: The Onion still truly is America's finest news source:

[MadMojoMonkey]

First time a Rep POTUS has won the popular vote in decades.

It's a shame that the power of the presidential office takes about 4 - 5 years for changes made to be felt on the ground.
Which means that Trump got credit for Obama's policies, Biden got blamed for Trump's policies, and Trump is about to be praised for Biden's policies.
But again, it is what it is.


The US will survive another 4 years of a totalitarian fearmonger. We've gotten through a civil war, we will get through this.
It's just a shame that policies don't sway people's votes, but vibes do.

[oskar]

They're saying inflation/recession always favors the opposition. Even Kamala knew it... she leaned hard into the price of eggs in the last days. Unfortunately for her, this election existed within the context of all in which she lived and has come before. Fortunately for us, "it is only in the darkest night that you can see all the stars," and the night has never been darker, so thanks for that! Brilliant!

The small silver lining is that you can't run a campaign like that and win.

[oskar]

After Jered Kushner solved the Middle East, Elon Musk deals the final blow!
This administration is going to be epic. A confederacy of dunces.
https://www.nytimes.com/2024/11/14/w...smid=url-share

[MadMojoMonkey]

I heard a solid take that Dem policies are what Rep voters actually voted for, but Dem politicians utterly fail to validate the struggle of daily life.

Rep politicians connect by acknowledging pain, and it works every time.

[oskar]

If you just poll for policies, progressive policies are universally more popular than conservative ones, but elections are more of a vibe thing, I guess.

Kamala was just a bad candidate as well. Who blurts out "I have a Glock!" when you're not about to rob a liquor store. She gave the weirdest answers considering they must have workshopped them to death. Dems really should have just run a primary, and a proper one. No more Obama swooping in and anointing people. And every last one of the people in that campaign needs to never work on a campaign ever again. So many incomprehensible decisions. Refusing to go on the biggest podcasts, and instead going on something called "Call her Daddy" The optics of that! Nobody who doesn't already own a crocheted vagina hat will listen to Call her Daddy, so the only takeaway is that she went on a thing named "Call her Daddy." This is the kind of stuff they're trying to win over steel workers from Kentucky with.

Meanwhile Trump had his ass eaten by Lex Friedman for three hours straight. One question was: "When you're truthing on Truth-Social, are you usually in your office or are you on the couch?" - Actual question! And this is not because Lex is a Maga republican. Lex is a spineless pick-me yes-man who gives his guests a completely uncontested platform to talk about whatever the hell they want. Same as Joe Rogan. Why would you not take that opportunity? Absolutely baffling.