Why No First Contact?
It seems logical to believe that there has to be intelligent life elsewhere in the galaxy simply because of the vast numbers of stars with planets out there. You may have even used this site's SETI Calculator to generate a somewhat positive outcome in us having distant cousins. So where are they?
Good question. See the Fermi Paradox for more on this contradiction.
Here are some of the reasons why, even if intelligent life is somewhat numerous in our galaxy, we will probably never meet them.
Why No Intelligent Radio Signals?
A radio signal's power diminishes with distance by the square of the distance's inverse. For interstellar communications, this then requires an enormous amount of transmission power. Depending on the distance involved, the bandwidth and whether the signal was directional or not, an interstellar signal would probably require more electrical power than the Earth currently produces.
To receive intelligent radio signals we would need to know their radio frequency (and the number of frequencies is nearly infinite), their bandwidth, their modulation, the correct part of the sky to point an extremely directional antenna to plus the date and time to receive the signals. It is not possible for any one of these requirements to be known ahead of time, but all are needed for a successful alien radio contact.
It gets worse. Because intelligent radio signals would be exceedingly weak we would also need extremely sensitive receiving equipment. It would be best to locate this equipment outside of our radio wave semi-absorbing atmosphere and place it in a radio-quiet area such as the far side of the Moon. However, even the Moon's far side can not escape that the universe is itself not entirely radio-quiet.
This all means that it's probably not possible for us to receive intelligent radio signals, and for the same reason, for other intelligent life not to be able to receive ours.
If one day we actually do hear intelligent radio signals could we understand them..., and just what should we do with them? In receiving such a transmission the time needed for our reply to be received by them, plus the time needed to receive their answer would total hundreds and more likely, thousands of years. As such, would they or us, even remember the signals were sent? Upon receiving an answer would their species or ours, still exist anymore?
These obstacles demonstrate that successfully receiving intelligent radio signals, and certainly having two-way communications, is at the very least extremely difficult, and more likely, not possible.
Overcoming the Extreme Travel Distance
The SETI Calculator shows that even with many possible ascension species in the galaxy the distances between them, when randomly distributed through our galaxy, would be exceedingly great. This creates multiple complex problems...
It is widely accepted, as Einstein explains, that nothing with any mass can exceed the speed of light. We are therefore limited to traveling at under the speed of light. This means a lot of travel time.
Using current technology we could send an unmanned spacecraft at the fastest speed ever done, 45 km/sec, to our closest star system..., Alpha-Centauri at 4.3 light-years distant. Being a multiple binary star system and of the wrong stellar classification, we already know that it's not a habitable place for life. One-way travel time for this fastest-ever spacecraft would be 29,000 years, and this to get to a place that we probably wouldn't want to go to. Do we have the time and need for this kind of exploration?
Manned or unmanned, let's say we can somehow get to 99% of light speed. The closest planets that are habitable are probably hundreds or thousands of light-years distant. Then double that time for a human crew or radio data, to return home. How do we survive a trip even if one-way, that takes this much time? The more food, water, breathable atmosphere, fuel, and supplies we bring along for this amount of time and speed will require a larger corresponding amount of fuel, plus increased spacecraft size to accommodate it all. Is this somehow doable?
Let's say despite a distance of 500 light-years, such a trip becomes a priority because we finally found an ascension species or an Earth-like planet out there, and we can travel at 99% of light-speed to get there. Our spacecraft would need multi-generational crews. Would subsequent generations of crews even want to continue with this mission? Could humans survive entire lifetimes and centuries of time, in the extreme isolation and confinement of a spacecraft? Even if the mission were successful so much time will have gone by that when humans finally arrive will this ascension species still be there, will they have become extinct? Or worse, maybe our weak distant data was wrong and there never was anything there?
There are still more problems ...
Time Dilation – time changes with extreme speed. This prevents us from getting close to the speed of light.
Energy Required – it's simply enormous. According to Einstein's Special Theory of Relativity as one approaches the speed of light its mass increases exponentially and with it, an exponential increase in fuel energy is needed. The numbers simply become impossible regardless of how much technology or energy is behind it. To help overcome this and the issues of time change due to dilation, it is thought that the best maximum speed to travel at is about 70% of light-speed. Even at this reduced speed each kilogram of spacecraft weight requires the energy equivalent of more than five megatons of TNT. This is the energy equivalent of 400 Hiroshima sized atomic bombs, just to get that single kilogram of spacecraft weight accelerated to 70% of light-speed. Then, upon arriving at our destination that same extreme amount of energy is now needed again for each kilogram of spacecraft weight just to slow the spacecraft down so it can be placed into a planetary orbit. Would humans ever be able to do this?
Inter-Stellar Dust – a spacecraft impacting with just one gram of interstellar matter at a speed of just under that of light would release on that spacecraft the energy equivalent of 70% of that same Hiroshima bomb. Traveling at 70% of light speed would still release 37% of the energy of that atomic bomb. One would not be able to detect such small amounts of matter beforehand or at the extreme distances needed. Even if we could, at this extreme speed the time to impact would be measured in milliseconds. Further, a spacecraft at such extreme speeds is simply not steerable due to its massive amount of inertia, the centrifugal forces involved, the extreme stress on the spacecraft's superstructure and the large amount of energy needed to move the ship in just milliseconds to avoid an impact. Any impact along a 1,000 trillion kilometer trip (100 light-years), no matter how small a mass, destroys that spacecraft.
The Cost – would society be willing to spend a crippling amount of financial resources and time on such extreme risk mission?
I've painted a pretty hopeless outcome here. But maybe I'm wrong.
What if traveling immense distances is somehow doable? Perhaps there's a way around the laws of physics, something we don't now understand that allows us to travel vast distances in short periods of time? If so, then why hasn't any ascension species instead visited us? We have had no extraterrestrial contact ever..., not in our lifetimes, not in human history, not even before humans walked the Earth.
Our Earth has been a paradise of forest-filled continents, oceans filled with life, a moderate climate and a breathable atmosphere for about 300 million years (Man has only been around for about 3 million of those years). If an intelligent species came to our paradise in the 297 million years before we walked the Earth, why didn't they stay? Why come that vast distance and not colonize the paradise we call Earth? Why are there no fossil records of this alien species or any remnants of their great civilization here on Earth?
Is it because they are not able to come to Earth, being confined to their own solar system and the laws of physics, like we probably are? Or is it because there are no ascension species, other than ourselves, that exist?
Are we the only ones?