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krrazypassions's avatar

How can inter-galactic communication between humans and aliens be practical?

Asked by krrazypassions (1345points) May 11th, 2011

Our universe is so big that it renders all inter-galactic communication impractical!
Suppose we build a powerful telescope and we spot intelligent aliens on a planet in a star system 1 million light years away, we will still be seeing their life as it happened 1 million years ago- since light from those times reached us today. So we wouldn’t know if they are alive today.
Anyways, assuming someone intelligent enough is still around- if we send them a message, would we know if they received our message, considering it would take another million years for it to reach them, and another million years for their reply to reach us. Would we humans be around for that long?

Taking it into real-world example- S.E.T.I. in Berkeley has been trying since many years to get in touch with any alien signals. Suppose we make a contact, isn’t it more probable that we may have found stray signals of lost alien civilization? or also, some aliens might receive our signals long after we are extinct- thus, isn’t it more probable that such attempts are futile in the universe we live in!

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18 Answers

dabbler's avatar

Your observations are correct as long as we’re limited to speed-of-light transmissions, and as far as I know we still are.

ragingloli's avatar

If I knew how to implement it technologically I would make a communication device that uses normal radio transmissions, or laser pulses, but sends them through artificial micro-wormholes.
And voilá, FTL interstellar communication without violating relativity.

marinelife's avatar

We have not yet broken the barriers to interstellar communication or travel. Science Fiction tell us that we will though.

flutherother's avatar

There seems no way that it could ever be done. Communication with aliens from the closest star in our own galaxy would be difficult enough.

Qingu's avatar

Quantum entanglement might do the trick, though I have no clue how this would be practical.

mattbrowne's avatar

Version 1: generating a gigantic intergalactic wormhole and using radio waves to communicate.

Version 2: quantum communication devices as suggested by @Qingu, but…

Here’s an interesting article

http://www.wired.co.uk/news/archive/2011-03/14/photon-qubit-routed

“The switch built by the researchers is the first all-optical device suitable for single-photon quantum communications, allowing qubits to be routed along a fiberoptic cable without losing their entanglement. With a common transport mechanism shared among the users of quantum information, photon qubits could be routed in exactly the same way regular bits of information are routed today.”

To demonstrate the switch, Kumar and his team produced pairs of entangled photons, and pumped them into a standard telecom-grade fibre, with one of the pair passing through the all-optical switch. On the other end, the researchers found that the quantum state of the photons hadn’t been disturbed—the entanglement information was intact.”

So here’s the “but”:

We don’t have access to the second photon in a distant galaxy. Only the aliens have. So we got to talk to them first using radio waves before we can use quantum entanglement. But radio waves are “slow”.

Qingu's avatar

It would be nice if the aliens from billions of years ago have already sent us radio waves explaining how to quantum-entangle communicate with them.

mattbrowne's avatar

They did. So let’s keep SETI alive!

flutherother's avatar

@Qingu Unfortunately quantum entanglement can’t be used to transfer information.

krrazypassions's avatar

@flutherother as of yet, yes, but we are working towards it… #Quantum Computing

flutherother's avatar

Quantum computing is viable but faster than light communication using quantum entanglement is never going to work according to quantum theory.

krrazypassions's avatar

Lets see how we could go about an Entanglement Communication System.
First we construct the most basic machine of this kind:You take a pair of entangled particles. Now, you separate them from each other by a very large distance. (this act of separation is what will take a long time… once we invest that much time, the rest of the processes shall be instantaneous, thanks to Entanglement!)
however, once in their desired places, one can change one particle in a particular way and its entangled partner will also change in exactly the same way. (am i right, isn’t this what entanglement is? “Spooky action at a distance”)
Now, if these two particles are at large enough distances, we will be making faster-than-light communication. How is this impossible according to Quantum Theory?

Does Quantum Theory imply that, perhaps, entanglement cant go on indefinitely as we move the particles away from one another- that maybe entanglement will fail after a certain distance?

flutherother's avatar

@krrazypassions Entangled particles stay entangled however far apart they are. You could have a photon here on Earth and its entangled twin in the most distant galaxy. However as I understand it you cannot make a change to one particle and observe the same change in it’s entangled partner and so communication is not possible.

krrazypassions's avatar

@mattbrowne hi! you said, “They did. So let’s keep SETI alive!” What were you talking about?

mattbrowne's avatar

@flutherother – So how useful is Kumar’s device then?

ragingloli's avatar

@krrazypassions
He may be referring to the WOW!-Signal

krrazypassions's avatar

ok, i’ve read about that one. But that was just a one-off incident. No one could spot that signal ever again :(

flutherother's avatar

@mattbrowne Dr Prem Kumar’s device will transmit quantum bits over fibre optic cable at very high speeds but never faster than the speed of light. It sounds interesting and has tremendous potential but this is different from quantum entanglement. Entangled particles ‘know’ what is happening to each other instantaneously, so called ‘spooky action at a distance’ but annoyingly this phenomenon can in no way be used to transmit information.

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