Is Finding Et Becoming A Viable Reality?

[naomi24]

In an attempt to leapfrog the planets and vault into the interstellar age, a plan to send a fleet of robot spacecraft no bigger than iPhones to Alpha Centauri, the nearest star system, 4.37 light-years away, has been announced.

A rocket would deliver a “mother ship” carrying a thousand or so small probes to space. Once in orbit, the probes would unfold thin sails and then, propelled by powerful laser beams from Earth, set off across the universe.

Any returning signals would take 4 years to reach us, but it will take 20 years for the probes to reach Alpha Centauri as opposed to Voyager 1’s 70,000 years.

Exciting stuff!

http://www.nytimes.com/2016/04/13/science/alpha-centauri-breakthrough-starshot-yuri-milner-stephen-hawking.html?_r=0

[Hypognosis]

@jim

Inverse square law is easily demonstrated by shining a torch on a wall and watching the bright patch as you back away from the wall.

That is an analogue of Voyager's problem (torch's parabolic reflector, likened to Voyages transmitter reflector).

Now, if the probe is talking back to us by laser beam and laser beams behave in a special manner, whereby they don't spread in the way that torchlight does, then I get what you're saying.

Next question has to be "how much laser power can a microchip-sized ship put out?"

After that, what would be the angular spread of a 1mm laser at a range of 40 billion kilometres (or whatever the actual value was)?

If weak signal is an issue then maybe just re-transmit each digital data packet a few hundred times until a 'concensus' value is reached. (Apologies for plagiarising Voyager team, if that's exactly what it does).

Alternatively, give the 'fleet' some kind of mutual synchronisation and data-sharing and get them all flash together, like a firefly swarm. This widens the beam heading our way and means it doesn't matter if dozens out of 100 are not aimed correctly.

[Old_Geezer]

The bigger problem, Ron, is that the aliens may not subscribe to the right network and so only be able to make emergency calls anyway.

[Hypognosis]

//whiskeryron
the idea sounds good but how is it possible to determine if intelligent life forms elsewhere in the universe developed in the same way as life on earth, //

I could over-interpret that sentence and put all the stress on the words "in the same way" and go off on one about how unlikely it would be for evolution to play out in the same way and the history of their civilisation to play out in a similar way but that would be far too long-winded.

Intelligence is like a place, which a species arrives at: the precise route it takes to reach it is immaterial except in that it must be a sufficiently rocky (figuratively) and intellectually challenging road in order to select out winners from fallers.


//would they know how a mobile phone works ?
10:25 Thu 14th Apr 2016//

If Americans had remained content with a pace of life in which the Pony Express was enough to communicate across the long distances between towns then there would have been no pressure to develop the telegraph and, without that seed, the string of inventions which was to follow either does not happen at all or has to wait for some other impetus. I like to think that all technological leaps are somewhat inevitable and merely await the necessity of making them happen.

Having said that, there is no reason that their phones' internal software would match our own and it is only because of international communication standards that phone handsets from the various phone manufacturing countries can interface with one another at all.

[jim360]

Hypo, I don't need to demonstrate the inverse square law to myself (and jomifl, this isn't an April Fool either...). The point is that it can be either suppressed over a certain distance, essentially by forcing the transmission to be far more directional, or otherwise accounted for at the receiving end by careful signal-to-background analysis. In either case, the problems involved are far from trivial, but I don't think they are impossible to overcome even over light-year distance scales.

Targeting the Earth is surprisingly easy (ironically, partly because of the inverse square law...), in principle at least, because the Sun will show up as among the brighter stars when seen from Alpha Centauri, and because the signal will certainly spread out over the transmission you need only point it in that general direction to be sure of hitting the Sun, and so also the Earth.

[jomifl]

Jim, you cannot have it both ways, either you have a highly collimated beam that has to be aimed with a degree of accuracy that is impossible in the real universe or you are spreading a few watts of radio signal over 25,000 billion square miles of the Earth's orbit. You would need an antenna the size of the solar system to detect it.

[Hypognosis]

@jim

So you are saying that inverse square law only applies to incandescent light sources, which (sort of) spray photons in all sorts of directions? Hmm, from experience, we know the torch with a parabolic reflector still has a spreading beam and, with LED torches, this post is already an anachronism.

So, just how non-inv-squarey are lasers?

I've seen that thing where they fire lasers at the reflector left on the moon's surface and they needed some kind of photomultiplier to register the (strangely sporadic) returning photons. Apparently, the beam is already feet across, when it reaches the moon.


Off-topic extrapolation: what if a distance-record galaxy was not just massively red shifted but its outgoing photons had spead apart so much that none of them scored direct hits on earth. With inv-sq law in mind, the highest red-shift objefts must be belting out light in huge quantities to be seen at all,
from this far away.

[Matheous-2]

To quote Astronomer, Martin Reece; "Abscence of evidence, is not evidence of Abscence" on the question of ETs......I believe all will be revealed, hopefully in this lifetime.

[naomi24]

^It would be good to think that all will be revealed at some time, but sadly I doubt it will be within our lifetime.

[jim360]

I might post this in a separate thread if you don't see it here, Naomi. BUt thought you might be interested in this one:

http://www.bbc.co.uk/news/science-environment-37167390

[naomi24]

I've seen that, but thanks for thinking of me, Jim. I appreciate it. All very exciting!!