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Powerful Radio Signal from Deep Space

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Re: Powerful Radio Signal from Deep Space

#41

Post by syshum »

dvh wrote: post #5
agoodthrowaway wrote: post #4

One thing that I wonder is whether we could ever identify an alien communication signal as an alien signal is likely to be much more advanced. In that scenario, the alien civilization is likely to be able to send their signal at the Shannon limit. Additionally an advanced civilization is likely to be sending signals optically instead of over radio waves. But even if we assume radio waves, Shannon says that the you ca…

It's too short for communication. I think it's burst of particles that are released when spaceship goes out of warp. https://www.universetoday.com/93882/warp-drives-may-come-wit... 16 day regular cycle is because it's regular transfer between two planets. Other FRBs are random because they are just random ships on random research routes.

Or they are heading straight for us but can only stay in warp for 16 days at a time.

Re: Powerful Radio Signal from Deep Space

#42

Post by zh3 »

Tepix wrote: post #21
zenmaster10665 wrote: post #15

Earlier quoted context omitted.

if they are sufficiently advanced, they would likely understand that other civilizations require primitive bands/encoding?

It could be considered a clue check. If you're unable to recognize and decode the signal, you failed the test.

Back in the days before radio, peple searched for life on the moon by using telescopes to look for signal fires.

Re: Powerful Radio Signal from Deep Space

#43

Post by DataGata »

_1100 wrote: post #34
runawaybottle wrote: post #33

Earlier quoted context omitted.

Would it really take an Armada? Coronavirus infected 40k people, we have some of these viruses in labs. I’d send one agile team and drop a nice virus on Earth (minimal viable product).

In the book, they start by sending as little as 3 protons, and it completely debilitates humanity.

The protons as you call them are a fun quirk of the science fiction genre, "How do we explain the Great Stagnation"? Fine Structure by Sam Hughes is the first book I've ever seen do it.

Re: Powerful Radio Signal from Deep Space

#44

Post by mc32 »

runawaybottle wrote: post #33
_1100 wrote: post #31

Earlier quoted context omitted.

The Three Body Problem is a first-contact trilogy of books that starts just like this: Someone ponders what the most powerful thing in our area is (the sun) and then finds a way to influence it just enough so that it can send repeating signals. From there the alien armada heads our way and sets up the plot of the rest of the trilogy!

Would it really take an Armada? Coronavirus infected 40k people, we have some of these viruses in labs. I’d send one agile team and drop a nice virus on Earth (minimal viable product).

Maybe they’d have competition on the way here? I mean, if there is one intergalactic traveling life forms, why not multiple? Not that they have to be foes... but you can’t presume that they aren’t.

Re: Powerful Radio Signal from Deep Space

#45

Post by jhoechtl »

zh3 wrote: post #32
richk449 wrote: post #24

Earlier quoted context omitted.

> But even if we assume radio waves, Shannon says that the you can send the most information when using a random code. As you approach the Shannon limit the signal becomes more noise-like as the encoding tends towards random. The waveforms we currently use for high data rate communications are already pretty close to the Shannon limit. I'm willing to bet the aliens will tolerate a 30% reduction in data rate if it mea…

There's a simple proof of this; an optimally compressed signal will have all symbols occuring with equal frequency (otherwise you'd be able to compress it more). So yes, an optimally compressed signal is indistinguishable from noise. However that's the theory; in practice the range of frequencies the signal occurs over and how strong it is at each frequency tells you a lot about whether it's likely to be an informati…

They send sognals to be heard and discovered. Why would they try hard to disguise if it's meant to be heard by another civilisation?

Re: Powerful Radio Signal from Deep Space

#46

Post by giantrobot »

agoodthrowaway wrote: post #4

One thing that I wonder is whether we could ever identify an alien communication signal as an alien signal is likely to be much more advanced. In that scenario, the alien civilization is likely to be able to send their signal at the Shannon limit. Additionally an advanced civilization is likely to be sending signals optically instead of over radio waves. But even if we assume radio waves, Shannon says that the you ca…

The inverse square law pretty much guarantees we're not going to ever detect random emissions from some alien civilization. The only way to get discernible signals an interstellar distance is with highly directional transmissions. So if we were to ever detect a signal from an alien civilization it would be a deliberate one.

There's properties of coherent signals that would stand out significantly from natural sources. Even if the message looked like noise the properties of the signal would give it away as being artificial.

A directional signal would be a point source so a simple off-axis check of the receiver would tell you if it's a distant or local signal. In order to maximize ERP a signal would also likely be a very narrow bandwidth. If we have a long enough sampling of a signal it'll also show distinct Doppler effects of coming from a rotating planet in orbit around a star. An intelligent civilization would also likely use some universal mathematical properties in the chosen frequency.

A signal, even one densely coded with information, would stand out against the background of space. Even if it appeared as noise due to dense information coding it would still have a narrow bandwidth, likely some non-natural mathematical properties, and come from a source that isn't some type of known magnetically active phenomenon (pulsar etc).

A signal deliberately sent to other stars is more likely to look like the Arecibo signal than WiFi. It would take an infeasible amount of energy, enough to vaporize the transmitter, to send a densely coded wideband signal that would be intelligible a handful of light years out let alone dozens or hundreds.

Re: Powerful Radio Signal from Deep Space

#47

Post by yumraj »

dvh wrote: post #5
agoodthrowaway wrote: post #4

One thing that I wonder is whether we could ever identify an alien communication signal as an alien signal is likely to be much more advanced. In that scenario, the alien civilization is likely to be able to send their signal at the Shannon limit. Additionally an advanced civilization is likely to be sending signals optically instead of over radio waves. But even if we assume radio waves, Shannon says that the you ca…

It's too short for communication. I think it's burst of particles that are released when spaceship goes out of warp. https://www.universetoday.com/93882/warp-drives-may-come-wit... 16 day regular cycle is because it's regular transfer between two planets. Other FRBs are random because they are just random ships on random research routes.

Damn, those are some punctual aliens, never early or late.

Re: Powerful Radio Signal from Deep Space

#48

Post by bitminer »

lovelearning wrote: post #8

More like "powerful radio emissions from deep space". The paper doesn't use the term "signal" at all, and a website dedicated to science probably shouldn't have either (although it did help bait my click).

FRBs are chirps. Something like a "signal". Much more signally than the hiss from stars and galaxies.

Re: Powerful Radio Signal from Deep Space

#49

Post by rtkwe »

dvh wrote: post #5
agoodthrowaway wrote: post #4

One thing that I wonder is whether we could ever identify an alien communication signal as an alien signal is likely to be much more advanced. In that scenario, the alien civilization is likely to be able to send their signal at the Shannon limit. Additionally an advanced civilization is likely to be sending signals optically instead of over radio waves. But even if we assume radio waves, Shannon says that the you ca…

It's too short for communication. I think it's burst of particles that are released when spaceship goes out of warp. https://www.universetoday.com/93882/warp-drives-may-come-wit... 16 day regular cycle is because it's regular transfer between two planets. Other FRBs are random because they are just random ships on random research routes.

Hah inevitably any type of FTL or even near light travel seems to inevitably also make an incredibly powerful weapon. This is even better because it doesn't require crashing the vessel into anything to destroy it.

Re: Powerful Radio Signal from Deep Space

#50

Post by rtkwe »

agoodthrowaway wrote: post #4

One thing that I wonder is whether we could ever identify an alien communication signal as an alien signal is likely to be much more advanced. In that scenario, the alien civilization is likely to be able to send their signal at the Shannon limit. Additionally an advanced civilization is likely to be sending signals optically instead of over radio waves. But even if we assume radio waves, Shannon says that the you ca…

Incidental transmissions sure but intentionally sent signals would by design avoid going too close to that limit, at least for the preamble that describes how to decode the normal transmissions.
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