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The question is: What could they possibly be using instead of some sort of electromagnetic signals? There are only a limited number of fundamental forces in th

The question is: What could they possibly be using instead of some sort of electromagnetic signals? There are only a limited number of fundamental forces in the known universe (unless our current understanding of physics is completely wrong), not all of which lend themselves to being used for long-range communication. Gravity possibly could be used as a means of communication but I suppose it’d be rather slow and have a low bandwidth. Some sort of quantum entanglement-based form of communication might be possible though that contradicts our current understanding of how information can be transmitted in the universe. So, barring some fundamental shortcut such as Star Trek subspace, there aren’t too many options for interstellar communication.

millstone 8y ago
The fundamental forces are a starting point, but it's not right to assign special significance to EM. The great majority of mass in the universe does not feel electromagnetism. It's dark matter. Humanity's expertise in electromagnetism is driven by our biologically EM-sensitive eyes, our physical size, the energy levels that permit classical chemistry, and the timeframe in which we live our lives. Perhaps aliens exist with much larger physical forms, communicating with neutrinos over vast distances and larger time scales. Humanity would be completely blind to these signals.
- gus_massa 8y ago
  EM is much easier, any moron wit a HAM radio can broadcast to the whole Earth, and a similar upgraded version that is still small and cheap can be used for interplanetary communication. So I'd guess EM for usual communications, but the idea of something weird like neutrinos for special purposes is nice. I don't know the size of the current neutrino transmitter/receivers, but IIRC the size is about a big building. Even the initial EM device where smaller. About dark matter, the current understanding is that it is diffuse and there are no "dark star" or "dark planets", but I always prefer to wait 10-50 (100?) years to call it definitive.
colechristensen 8y ago
Why not expect new physics we simply don't have the tools to see yet? Maybe something that only shows itself at very high energy or interacts only with neutrinos or antimatter or some exotic matter that isn't produced with fusion or supernovas. What about beings that operate at very different time scales? What if there is some encoding scheme that blows our information theory out of the water so communication just looks like white noise? What if evolution converges to a single shared consciousness or fierce independence and communication just stops being interesting after a certain stage? Or if non-interference is the very well enforced law of our corner of the galaxy? I think it's hubris to think that we know the answers to all of the questions for physics or at least we know what we don't know. My assumption is that there are questions/problems/phenomena that we don't even have the context yet to imagine.
- raducu 8y ago
  Then the answer is: we can only rule out intelligent life as we CAN immagine it. Sure, there could exist intelligent life of sorts that we cannot comprehend, that use physics outside of the standard model; God perhaps?
- majewsky 8y ago
  > What if there is some encoding scheme that blows our information theory out of the water so communication just looks like white noise? You don't even need a new encoding scheme for that. Compressed data looks like white noise unless you know the decompression algorithm.
  - dogma1138 8y ago
    Compressed data doesn’t looks like noise correctly encrypted data can. That said however metadata will often be unencrypted and even encrypted data will have discernible patterns for example the transmission of say a 2.4ghz radio network with packets will look like white noise even if all packets are encrypted as you need to somehow modulate the signal for transmission control.
    - 8y ago
robocat 8y ago
Or an advanced civilization uses low power transmission with high compression codecs, maybe with spacial (cellular) dispersion. Which of our modern transmissions would be decoded by someone from 75 years ago?
dingo_bat 8y ago
> Gravity possibly could be used as a means of communication but I suppose it’d be rather slow Doesn't gravity "travel" at the speed of light just like EM radiation?
- Bouncingsoul1 8y ago
  Yes but the frequency is way lower, so maybe less information/time.

millstone 8y ago

The fundamental forces are a starting point, but it's not right to assign special significance to EM. The great majority of mass in the universe does not feel electromagnetism. It's dark matter. Humanity's expertise in electromagnetism is driven by our biologically EM-sensitive eyes, our physical size, the energy levels that permit classical chemistry, and the timeframe in which we live our lives. Perhaps aliens exist with much larger physical forms, communicating with neutrinos over vast distances and larger time scales. Humanity would be completely blind to these signals.

gus_massa 8y ago
EM is much easier, any moron wit a HAM radio can broadcast to the whole Earth, and a similar upgraded version that is still small and cheap can be used for interplanetary communication. So I'd guess EM for usual communications, but the idea of something weird like neutrinos for special purposes is nice. I don't know the size of the current neutrino transmitter/receivers, but IIRC the size is about a big building. Even the initial EM device where smaller. About dark matter, the current understanding is that it is diffuse and there are no "dark star" or "dark planets", but I always prefer to wait 10-50 (100?) years to call it definitive.

colechristensen 8y ago

Why not expect new physics we simply don't have the tools to see yet? Maybe something that only shows itself at very high energy or interacts only with neutrinos or antimatter or some exotic matter that isn't produced with fusion or supernovas. What about beings that operate at very different time scales? What if there is some encoding scheme that blows our information theory out of the water so communication just looks like white noise? What if evolution converges to a single shared consciousness or fierce independence and communication just stops being interesting after a certain stage? Or if non-interference is the very well enforced law of our corner of the galaxy? I think it's hubris to think that we know the answers to all of the questions for physics or at least we know what we don't know. My assumption is that there are questions/problems/phenomena that we don't even have the context yet to imagine.

raducu 8y ago
Then the answer is: we can only rule out intelligent life as we CAN immagine it. Sure, there could exist intelligent life of sorts that we cannot comprehend, that use physics outside of the standard model; God perhaps?
majewsky 8y ago
> What if there is some encoding scheme that blows our information theory out of the water so communication just looks like white noise? You don't even need a new encoding scheme for that. Compressed data looks like white noise unless you know the decompression algorithm.
- dogma1138 8y ago
  Compressed data doesn’t looks like noise correctly encrypted data can. That said however metadata will often be unencrypted and even encrypted data will have discernible patterns for example the transmission of say a 2.4ghz radio network with packets will look like white noise even if all packets are encrypted as you need to somehow modulate the signal for transmission control.
  - 8y ago

robocat 8y ago

Or an advanced civilization uses low power transmission with high compression codecs, maybe with spacial (cellular) dispersion. Which of our modern transmissions would be decoded by someone from 75 years ago?

dingo_bat 8y ago

> Gravity possibly could be used as a means of communication but I suppose it’d be rather slow Doesn't gravity "travel" at the speed of light just like EM radiation?

Bouncingsoul1 8y ago
Yes but the frequency is way lower, so maybe less information/time.