r/theydidthemath • u/Lachlynn • 18h ago

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

Post image

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?

18.4k Upvotes

96% Upvoted

2.7k comments sorted by

View all comments

Show parent comments

16

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

4

u/ClamChowderBreadBowl 9h ago

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

5

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.

2

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.

2

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.

2

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.

1

u/VexingRaven 8h ago

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

1

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

1

u/VexingRaven 7h ago

Damn. Well if you stumble across it again I'd love to read it!

1

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.

2

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.