Communication with Another Civilisation
Are we alone; nobody knows. We are not aware of if we are unique in exactly the right circumstances occurring at exactly the right time. If the occurrences are commonplace, then numbers will be large, but so far, it’s been found that the earth seems to be of a rare type. A goldilocks planet, stable for a very long time, with an unusually large moon, in a goldilocks zone around a goldilocks sun, in a goldilocks area of the galaxy, in a goldilocks galaxy. The universe is normally a very dangerous and destructive place. If life is channelled and chemicals only really have one or two routes based on a consistency, then by force of numbers life may be commonplace to maybe 1 in a million stars, so looking at the general number per area, the average distance would be about 750 light years between each one or 4 x 10^15 miles. After about 44 years of travel Voyager 1, our farthest travelled man-made probe, has managed to reach 1.4 x 1010 miles, so has 15,000 times the distance to go at best. With the deep space network we theoretcially have a receiver the size of our planet, but I’m expecting us to lose all contact with it within a decade after travelling maybe down to 14,999 times the distance to go. If something knocks it off course we probably will never hear from it again.
If you look at time periods for organism proliferation it is always quoted that this can happen at exponential rates, but there is always the problems of time and resources. Exponential rates need exponential resources, and sadly we are eating into the worlds resources already at a rate that will probably see them run out within a short time. Run out before they are managed, and the exponential rate drops to near zero for a very long time, if at all it ever recovers. Game over as far as space travel goes for a million years.
So next we add to this technical ability. I would estimate that we have had a technical society that could communicate with an outside source for around 60 years out of probably a 300,000 years history. The communication capability of that time 300,000 years ago was nearly the same effective communication level as about 150 years ago. So we, at the moment, can figure in a communications capability length at the moment of about 0.05% of a species duration. If things don’t change, it would probably take a million years for the planet to revert or recover to ground level basis for minerals and the like, so communication ability longevity of a species overall is probably less than 0.01% of its duration.
If you believe in a certain level of synchronicity, like circumstances producing like results at the same level, then we may find that other civilisations may be very similar level to our own in capabilities and times. A bit like creatures appearing at the same time in large quantities in a particular area. Like circumstances producing like results.
So, if all of these come together to allow a civilisation to exist for a reasonable time period, how will be communicate? We probably need to communicate over distances that a suitable sun has trouble being seen at.
Let’s start with radio sources and angular dilution. We can discount a lot of sources like fast radio bursts and massive signals. If you have a civilisation that can produce such a burst, then you would probably fry every form of life out to Pluto. If we set one off, even Voyager 1 at the distance it is, would destroy every electrical component on it past repair. If it was a directed burst then you wouldn’t want to be anywhere in front of it, and it would be a danger to any spacecraft in its direction. So, a civilisation that could do this, you would want to communicate with, or tell them that you were there. But they’re probably fluctuating magnetars anyway.
Normal radio dish communications. The most powerful transmitter in the world is around 2,500KW. For a craft communicating with the earth we need to look no further than the 23W transmitter on the Voyager 1. The craft knows where to point a tight transmission, and on earth we know where it is to a few miles at any given time to receive it, so the directions are well known to allow for synchronisation, but even then, the reduction in broadcast is a factor of about 1019 times over a range of 1.4 x 1010 miles. If we compare a typical sun, our own, it probably transmits a continuous signal in all directions of around 4 x 1026 watts, so is around 1.6 x 1020 times as powerful as our best transmitter, 1025 times as powerful as Voyager 1’s. At our suns output value, we probably have a practical detection limit of about 100 light years. Past 200 light years and we might not even know it was there, the sun’s signal would be so weak, only discernible by the movement of larger objects. Anything above that and we need to start using very long-term observations and the best space borne telescopes. Even then we might manage an orders advantage, the majority of stars just not radiating enough even to show up as a small blip past 2,000 light years, so the majority of the universe is invisible to us, only galaxies 150,000 light years across, or cumulatively radiating say 1020 times the value of our sun, showing up as faint dots, because a cross section is beaming a portion in a very straight line to us. Any star not attached to a galaxy, the unproven assumption being that most are, would simply be classed as not being there, and not existing.
Earth’s shadow. The earth is travelling at about 67,000 miles an hour around the sun, so our shadow to a detecting civilisation based on the sun would be about 6 minutes’ worth at most. So, if we are to send a signal it has to be directly outwards to the sun, otherwise we would be lost in the sun’s noise. With the state of our world and if it was sent on at the start of the week, it could almost be a ‘sic transit gloria mundi.’
So, if we used the most powerful transmitter it would be around a reduction of somewhere near 1020000 times when it gets to another civilisation. You’d be lucky to get a photon every million miles reaching there. Not a lot of room for encryption of a video channel, so we won’t be broadcasting sky there yet.
We have beamed radio messages into space, from the 305-metre antenna at Arecibo, with an estimated 20 trillion-watt output (2 x 1012 watts), but it’s probably similar to lighting a LED on Pluto as far communications ability is concerned. Its duration was for 180 seconds. With angular components it may be a signal diluted over a few light year’s dispersion.
Laser transmission. The distance to the moon, between 225,622 and 252,088 miles, averaging 238,855 miles, is constantly being measured every day using LIDAR (Laser ranging and distancing). It sends a beam 250,000 miles starting out at a diameter of 0.76 metres, hitting the moon at 6.5 kilometres and reflecting back from a mirror placed there by Apollo 11, 14 and 15. By the time it gets back to us is has lost 1021 in power, taking about 2.5 seconds. One-way transmission would be about a reduction of 8,500 over 250,000 miles, admittedly, most of it due to our atmosphere and the losses are massive, but a similar laser over a light year would probably be a light year wide when it get to it’s destination.
We are spinning at around 1,000 miles an hour, the sun moving at probably a million miles an hour, so at best we are transmitting at a planet doing the same thing. But to send a signal there say of 10 seconds duration, even on a very tight single beam, we need to know where the receiver is, and at the precise time it will be there. Every 10 seconds the receiver will move 2800 miles. A day out and the receiver will move 24 million miles. That is point to point. If it constantly moves in the exact opposite direction or the same direction as the signal is sent it’s not a problem, but the opposite movement to us and it could be 48 million miles out.
Parallel Motion Tight Beam
Opposing Motion Tight Beam
Random Motion Tight Beam
Comparison of Voyager 1 and Likely Civilisation Communications by normal radio transmissions
As you can see from the last diagram the ratio of a likely star to Voyager 1’s distance, and therefore resulting spread of a radio wave, is around 15000 to 1, and it’s based on knowing exactly where to beam/look with a 34 metre dish.
Radio transmissions are just another form of energy like normal light. So it’s likely that we would not even notice a small sun over even a medium distance, and would miss most of what’s out their unless massively luminous or active. With angular emission, most of what’s out there would not even be noticed. Probably there is a cut off point at the distance each type of star is visible. Beyond this and making your detectors 10 or 100 times more sensitive would not increase your chances of detection as so little is transmitted due to this angular change. We would see the effects of gravity, but we wouldn’t see the object, the angular diffusion of distance peventing this. If there are floating planets out there I doubt if would could even spot one at 4 times pluto’s distance unless it happened to occult a close non-variable star. You wouldn’t see them, but there could be a massive number out there.
But meaning an active signal to another star would need fantasically precise timing not to be a light year out, that is sending it out knowing where it will be at an exact time. Back to Voyager 1 and it’s 15,000 year journey, a week out over that 15,000 years would mean a possible miss completely of 200 million miles. We ourselves only noticed a thing like Oumuamua because it was probably half a mile long and came within 20 million miles. If it had been 5 miles long we may have noticed it within a weeks error, but Voyager 1 is only really about 12 feet across, so if it had come between us and the moon we might have found it.
Would we go there ourselves? Unless we knew exactly where civilisation was we’d need to have people going to a lot of planets. This takes time, and resources and populations will hamper this, so the only thing we could do is send a massive amount of small robots and report back. If light speed cannot be exceeded this could take over 200 years between transits, but with limited and resources overall, it’s like that it would probably be 10,000 years transits with probably a loss of 99% of the robots, taking it to an effective 100,000 years. Unless it’s a gradually expanding civilisation with massive resources, by the time one gets back there probably won’t be anything to get back to.
Using the sun for directed semaphore transmission. So, it’s unlikely that we will ever be able to use radio transmissions, they’re just too dispersed. We can send laser transmissions, but we would probably need to do a continuous one directed at a known point for 100 years to say hello. What does that leave us? Neutrino’s again, but they are similarly very dispersed, and very low levels compared to star background emissions. We, at the moment don’t know how to modulate, encode or decode a neutrino band, most of it appearing to us just as random static. Would we recognise a message in it over our normal sun’s emissions? This may be possible in the future, neutrinos being normally able to pass through most things unchanged, but not at the moment. This leaves semaphore, where we can just block the sun in various directions, in light or neutrinos.
Semaphore is a simple option, where you just put something in the way of the sun in the direction you want to send, and let the suns power work for you, with the ability to let sunlight / neutrinos pass or not. Using a vast liquid crystal array warmed by the sun, you could send large distances via a focal point system. You can bunch it and put two poles up, and show the recipient a bunny rabbit if you like. Get it wrong, and a would-be friendly civilisation would may come here spoiling for a fight. Not the message of peace and goodwill to all lifeforms that was intended. ‘Typical bloody humans,’ aliens may bark or squeak. With larger things such as galaxies it may be possible to block directions, or use communication by galactic lensing, but sadly most are probably still limited to a possible few civilisations, even if they are out there.
We are left with the speed of light, can it be overcome or gone around? Sadly, most solutions depend on using star level or black hole outputs to do so. Warping space is easy if you have a few unused black holes, still in their wrapper, knocking around in the workshop. For the average creature we’re probably an average star’s lifetime away from that point, so we’ll need to stick to anti or negating gravity.
Humans are a compromise species. The design was for mobile processing unit of maximum power. So, the approximate optimum size is about 5-7 feet high. Any larger and the body would need to be substantial, requiring larger amounts of processing power just to control the body. Any smaller and the processing power would be severely hampered and the durability and resilience would be compromised. But how do you fit a system with secure processing ability in something so small. The amount of information that can be stored from the senses is vast, so only the highest percentage matching is stored. The amount of screening to securely store even that amount of information over time would be vast, requiring the brain the size of this planet to achieve, so the screening needs to be minimal, so the reliability of the return of information also will be similarly limited, and give highest percentage match returns. Now to speed. A purely electronic system would be the fastest, most efficient and reliable, but would take up enormous amounts of power and space, most tasks it being needed to perform being transient, not being extremely long-term dependent, and not requiring a particularly high level of precision. So, an electrochemical system is the best compromise. This means that the brain is highly mobile, but it leaks and blends information. If all the matter concerned in the project is quantum entangled then you could read out at any distance using an ultrafast newton’s cradle system to reduce uncertainty.