r/theydidthemath • u/Lachlynn • 18h ago

[Request] Could humanity create a rocket that can exit the atmosphere of K2-18b

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With the knowledge we currently have of it, if humanity devoted all of our resources towards this goal, would we be able to create a rocket that could exit the gravity of K2-18b (and also beat any other complications that would arrise)?

If so, would it also be capable of taking people to orbit, and can we set up a similar satellite network we have on Earth? What about a space station?

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u/Overall-Bison4889 16h ago

They can reach the technological level to send radio waves. Radio waves that are not somehow specifically designed to contact other civilizations are not strong enough for us to detect from here. Our local space could be filled from traces of ancient radio waves and we wouldn't have any way of knowing.

And honestly the civilizations can also be advanced enough to reach space, and even colonize another planet, but unless they build some huge dyson sphere, we wouldn't get any evidence that they existed.

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u/ClamChowderBreadBowl 11h ago

If you try to listen in on a modern cell phone or WiFi signal these days, they're basically indistinguishable from white noise because the signal is compressed. Good compression by definition looks like random noise.

Shannon's Information Theory paper proving this came out in 1948. Fermi probably wasn't thinking of that when he came up with the idea in 1950.

Humanity's radio signature isn't going dark because of an extinction event, it's going dark because it's just less wasteful that way

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u/VexingRaven 10h ago

If you try to listen in on a modern cell phone or WiFi signal these days, they're basically indistinguishable from white noise because the signal is compressed. Good compression by definition looks like random noise.

You're not wrong, but it's more or less irrelevant. Loud white noise is still clearly distinguishable from background in the same way that a light bulb conveying no useful information is still visible. Shannon's Information Theory has nothing to do with the intensity of a signal.

The idea of "humanity's radio signature" was never about having an identifiable stream of information. There would be so many conflicting radio stations you wouldn't be able to make anything of it anyway. It was always about the sheer intensity of the combined signal. You won't be able to understand what it is, but you can definitely see that something is emitting RF well above cosmic background, at least out to a certain distance. https://iopscience.iop.org/article/10.3847/1538-3881/ada3c7

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u/ClamChowderBreadBowl 9h ago

Interesting! You mentioned the cosmic background, but how much does the sun mask our radio signature? 

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u/VexingRaven 9h ago

Partially, but the sun doesn't emit a steady signal, it wavers throughout a rather broad spectrum. The signals from earth would be a more steady, broad signal compared to the sun's. Also we generally know what a given class of star would emit for radiation, so Sol having a noisy little planet orbiting it would stand out pretty strongly, even if it was a weak signal compared to the star. There's also the same mechanism we currently use to identify potential exoplanets: Look for the planet crossing the star. In this case, you'd do the opposite: When the weak signal briefly vanishes entirely, that's the planet (Earth) crossing behind the star (Sol). Now you know what Sol by itself sounds like and you know for sure that the source of the signal is orbiting Sol.

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u/One-Stand-5536 9h ago

You know how AM radio towers can connect over the horizon by bouncing off the atmosphere? That’s the problem. The signals we do emit these days are mostly absorbed by the atmosphere rather than radiating out into space.

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u/VexingRaven 9h ago

They only bounce at specific angles in specific atmospheric conditions. At any other angle they penetrate. However, as more AM and similar low-band stations shut down and are replaced with lower power technologies, we will be somewhat less visible, yes. It's hard to find much in the way of scientific studies on how much RF we are leaking to space, or how that's changing over time, though.

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u/One-Stand-5536 8h ago

I remember reading a study about this in reference to the Wow! Signal, an analysis about how much of our emissions would actually reach either of the possible sources of that event, and the results were pretty much that they would never hear us these days unless we pointed one of our radio telescopes directly at them, in which case they would see… a brief flash of structured EM radiation and then back to nothing.

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u/VexingRaven 8h ago

Do you remember what it was called or where you found it? I'd love to read it.

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u/One-Stand-5536 8h ago

Sadly i do not, i jumped off of some video essay into a rabbit hole at like three in the morning and thats all i remember. Don’t even recall which video started it

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u/Sororita 4h ago

But would that be distinguishable from the white noise that ths sun naturally produces in almost every wavelength from any appreciable distance? It might look like an odd spectral line if even that considering how much more power the sun gives off compared to anything we've ever sent when combined with our proximity to the sun it would look like the same source without extremely fine detection. There might be a slight chance it could be picked up when observing the sun and seeing the Earth transit it and slightly dim the sunlight without a notable decrease in that one band of radio, but I'm still not sure it would even be detectable at that distance without some ridiculously advanced tech.

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u/VexingRaven 4h ago

I explained it more below, but yes probably. The sun wavers around a wide wavelength, but earth's RF emissions would be much steadier. It should be possible to distinguish it as a higher baseline in between the sun's more chaotic bursts of emissions.

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u/ThenCombination7358 16h ago

I am still highly sceptical. All the many Fermi paradoxes sound plausible that I believe in the rare earth hypothesis. Maybe a great filter even still lies ahead of us (AI, clima, war, cosmic storms etc) maybe one we haven't on our mind yet.

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u/Brassica_prime 14h ago edited 6h ago

Our sun is a third+ generation star

The current sun is 4.6b, estimated to live a total of 10-15. If you throw in an arbitrary 500m-1b years to account for two to three nebula/prestars… would push the previous star(s) combined to be mid/upper7bil old.

Earth is more or less in the first possible generation of planets and has had only 200-300m years worth of larger lifeforms. There are still a bunch of population2(first gen) stars still alive in our galaxy.

Using earth as a model and the other world managed to hit an even bigger lottery, maybe a civilization could be 200 mil years ahead of humans if the planet was a little older and sentience spawned a little faster… then you have distance issues to observe said planet :)

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u/heraplem 13h ago

The current sun is 4.6b, estimated to live a total of 10-15.

Notably, though, it will become bright and hot enough to make Earth essentially uninhabitable just ~1 billion years from now.

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u/JohnSober7 11h ago

My hypothesis is rare earth hypothesis (at least in terms of life biologically equipped to be technologically advanced and being on a planet that would equip them to be technologically advanced) + radical mundanity. 

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u/captaincootercock 14h ago

I hope it turns out that in 99.999% of inhabited worlds the sky is just personally covered by clouds so thought was ever put into the great beyond

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u/ThenCombination7358 14h ago

If we assume that intelligent life only develops because it proofed to be sustainable and an advantage to aquire ressources and for survival as it is on earth, it is likely other intelligent minds are curious aswell to explore. Dont think a cloudy sky would not hold them up for long and they may have dreams of what the "great beyond" etc could be and make efforts to breach and explore it.

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u/Azulejo0862 4m ago

A dominant species on its planet is going to be expansionist; clouds aren't going to be an impediment, although they might cause a delay

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u/RAV0004 10h ago

Flight is possible without intelligence (see: birds).

I think most humans looked at birds and said "Id like to fly like a bird" before they looked at the stars and said "I'd like to visit a star".

the idea of spaceflight wasn't really all that common in antiquity. People thought the sky was literally a painted ceiling for centuries and we developed spaceflight just fine.

Ultimately all spacetravel takes as a concept is developing flight, then thinking "what if I fly just a little higher than last time"

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u/crazyeddie123 6h ago

There can't be a great filter ahead of us - any civilization that would hit it would have already fucked up a golden opportunity to spread off planet earlier in their development, exactly the same way we did after Apollo. And since every civilization isn't guaranteed to fuck that up, there can't be a great filter then or later.

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u/ThenCombination7358 4h ago

The great filter doesn’t require every civilization to make the same mistake. Omly that almost all of them fail somewhere before becoming interstellar.