The Von Neumann Problem - Where Are All The Aliens?
It was in 1948 when John von Neumann wrote his paper "The general and logical theory of automata," in Cerebral Mechanisms in Behavior: that his interest in self-replicating machines first became apparent. Von Neumann was a mathematics genius and contributed to the fields of quantum mechanics, mathematics and applied mathematics, writing 150 papers during his lifetime.
However it is his theories surrounding self-replicating computers that are the most widely known and have been at the centre of many debates over the years.
Perhaps what is most remarkable about von Neumann's early work, is that he began it before the discovery of DNA and therefore was not fully aware of how living planetary organisms replicated.
Von Neumann theorised many types of self replicating probe, however it was his work on kinematic self-replicating machines that really caught the imagination.
The theory was that a machine would be able to replicate itself with just four elements, that is to say:
A constructor that can build a machine, when fed explicit blueprints of that machine.
A blueprint copier,
A controller that controls the actions of the constructor and the copier.
A set of blueprints, explicitly describing how to build a constructor, a controller, and a copier.
As you'd imagine this simple theory has captured the imagination of science fiction writers and cosmologists alike. In fact we could say; it has put the proverbial cat among the pigeons.
Fermi's Paradox - The First Set Of Pigeons
The Italian physicist Enrico Fermi postulated the argument that seeing as there are around 200-400 billion stars in the Milky Way alone, and that several tens of millions of those stars are similar to our own sun. Plus many of those stars are billions of years older than us, the argument for intelligent extra-terrestrial life is extremely strong.
Yet with all of those stars, and all of those planets circulating those stars we have had no concrete evidence of alien life, this came to be known as Fermi's Paradox.
Stirring The Paradox
In 1981 American physicist Frank J. Tipler claimed to have solved Fermi's Paradox. Tipler used the von Neumann probes to do so, the argument is explained like so:
If indeed life is replicated throughout the galaxy, and suns that are billions of years older than ours have intelligent life orbiting them.
Then the chances of us being the first civilisation to think about creating von Neumann probes is slim to none. In fact the galaxy would be crawling with these machines by now, making them impossible to miss.
Ergo . . .
There are no aliens.
This argument is pretty hard to shake, because indeed we may launch (within the next 5-15 years) our own version of (non-replicating) von Neumann probes.
Project Dragonfly was a competition launched by the Initiative for Interstellar Studies and was attended by teams from four qualifying universities. The winning results showed that we are not far off being able to accelerate a small probe to around 10% light speed (10% c) using an earth bound laser and a solar sail.
So if we are close to doing it after evolving on a circa 4.5 billion year old planet, surely we can't be the first?
Sagan's Response
The renowned astrophysicist Carl Sagan, along with his colleague William Newman, responded to Tipler's argument by saying that he had vastly underestimated the replicating powers of such machines.
That in fact von Neumann probes would be so destructive in their self replicating abilities, that any intelligent species would not make them, and would destroy any they found on sight.
Further arguments supporting Sagan's response are that such machines could be built in with a kind of Bladerunneresque limited lifespan, whereby they would self destruct after a certain amount of time.
Other arguments say that with simple radio transmissions, machines could monitor each other and not self-replicate if they were in a certain amount of cubic parsecs of each other.
Touching The Void
For me there is a final argument which hasn't really been explored, and that is that such probes do exist, but they do not self-replicate. Or at least if they do, do not pass on their self-replicating abilities.
Which means that their progress across the galaxy would be a lot slower than the original half a million year estimation by Tipler, and they are on their way here and at some point we will see one.
If one has been sent from say 51 Pegasi, a star located about 50.1 light-years from earth, then a probe travelling at 10 percent the speed of light would take 500 years to get here, and that's if they were lucky enough to point it exactly in our direction.
That's a big if, because at that distance just a fraction of a degree this way or that, could mean the probe misses us by trillions of miles.
I for one believe that interstellar travel is very difficult, not just for us, but for everyone, for the simple reason that the laws of physics that we have discovered are universal. Add to that that we are very small, and the universe is very big, then it is quite easy for alien civilisations to live within (astronomically) close distances and still not bump into each other.
Hopefully we'll launch our own von Neumann probe soon and point it at Proxima Centurai, where we have discovered a possible rocky planet orbiting close to the dwarf star. At four light years distance it is the closest one to us, however at the proposed speeds it will take over 40 years for the probe to reach its destination, and then a further 4 years for the signals it sends back to be received on earth.
So hopefully I will live well into my nineties to see the results! Either that or I'm hoping we discover someone else's von Neumann machine pretty soon!
We are not alone, of that I am (almost definitely) sure!
WHAT ABOUT YOU; WHAT'S YOUR TAKE ON FERMI'S PARADOX AND VON NEUMANN PROBES? WHY HAVEN'T WE SEEN ALIENS YET? DO YOU BELIEVE THEIR EXISTENCE IS INEVITABLE, IF SO, IS OUR BUMPING INTO EACH OTHER EQUALLY INEVITABLE?
AS EVER, LET ME KNOW BELOW!
Sources
Kinematic Self-Replicating Machines - MolecularAssembler.com
Self-replicating spacecraft - Wiki
The Artificial Self Replication Page - Mosheshipper.com
Title image: Greg Rakozy on Unsplash
I once calculated the amount of antimatter it would take to get a good sized ship up to 50% light speed. It is a lot.
You need these speeds to avoid generation ships and it looks like the amount of energy needed for space travel is prohibitive.
Unless we modify our lifespans to last thousands of years I think that the stars will remain out of our reach.
It's a lot indeed, but we'll find a way, it's just a case of whether you and I will be alive when we do!
Cg
The problem with all of this theory, is that they sound logical.
Unfortunately, since science spilt physics from metaphysics, they will never see the answer that is right in their face.
See is NOT believing. BELIEVING IS SEEING.
We do not see aliens because we do not believe in them.
It is a part of free will. If we do not want to see and interact with aliens, then we will not. And there is nothing the aliens can do about it. It is also something we will have to learn before we are allowed to become a space fairing race. (not because anyone will stop us, but because without that wisdom, we will be stuck in a loop that we can never leave.)
It looks like man has decided that aliens are real, and in a few generations, everyone will "know" that aliens are real and we will have lots of contact.
You can get a set of night vision goggles and watch the space ships fly around at night.
You can go to many UFO hot spots, where many go to see have seen flying saucers.
But, the problem with all the above logic is that everything in our science books are wrong.
The speed of light is not the ultimate speed.
There is near instant communication across the universe.
Space is not linear.
The speed of light is not constant.
We do not live on a ball floating in space (vacuum)
Gravity does not hold the galaxy together.
We don't even know how to see other life yet.
There is life on planet earth that we are not even aware of.
Funnily enough I was thinking of you as I wrote this, in particular when I wrote 'the laws of physics are universal'. I thought to myself, good old @builderofcastles will have something to say about that :-)
Yet the very technology we are communicating with right now is based on that 'wrong' science. Pretty nuts huh?
Cg
:-)
Yep, it comes down to a difference between science and engineering.
Yes, there was a repeatable phenomena, and it has been utilized and developed into the modern binary computer and internets.
However, our explanations of those repeatable phenomena are incorrect, and so engineers are finding road blocks in scaling both larger and smaller of microchips. If they had correct science, they could be making circuits 100 times faster and less energy intensive, today. But now, we have to wait until someone just stumbles blindly upon something that works.
And maybe this time, they will say, "oooooh, maybe we should take into account the lumineferous aether, all of these anomalies simply work out if we use that."
"I for one believe that interstellar travel is very difficult"
That was the sum of my thoughts, and I learned something new here, as I never thought about Fermi's paradox. I feel a little slow.
Undoubtedly, there is life out there.
Does the fact that everything has been getting further and further apart since the Big Bang have any relevance? Or is that effect too slow, in comparison to the speeds vehicles could travel through space?
Thinking about Fermi's paradox, it would seem that the wormholes so prevalent in sci-fi, as a means to travel intergalactically, must be impossible to create, and must not exist naturally, at least as a means of facilitating travel.
While I think the human race will ultimately encounter aliens, I doubt it will happen in my lifetime, as if we haven't met for the last 6 million years, the chances are we won't meet for the next 6 million years. :0
Yes and no, yes because distant galaxies are flying away faster than the speed of light, and no because the effect is negligible for closer stars and galaxies, in fact we are going towards Andromeda and will collide with them in about 2 million years I think.
Possibly, or they simply haven't been created in order to visit us; or the aliens that have created them to visit us, are so far in advance of us, that they believe there is zero point communicating with us. Rather like us going back 6 million years and seeing our common ancestor, sure we'd observe, but there would be no point trying to talk to them.
I desperately hope you're wrong, but fear you may be right :-(
Cg
"if we haven't met for the last 6 million years, the chances are we won't meet for the next 6 million years"
"I desperately hope you're wrong, but fear you may be right"
Don't lose hope. Maybe Stargate is the literal truth, and the ancient Egyptian Gods were in fact a visit from aliens, who pushed our primitive ancestors about with alien technology.
Perhaps, they'll be back to give everyone a shock lol.
Or perhaps the black monolith from 2001 will turn out to be a thing, and show up again in 2021, and before we're 60, we'll all evolve into Supermen.
Maybe David Icke is more scientist than fantasist. Or perhaps that last suggestion is a step too far. :)
Lolz, I'm just hoping it's going to be like Star Trek First Contact, whereby we achieve some amazing space travel feat and then the aliens say, OK cook, now we'll talk to you.
Damn, where's that straw I was clutching gone?
:-D
Cg
Very good post! This is so interesting to think about @cryptogee, it's one of my favorite topics actually. When you see a dandelion struggling to grow through a crack in the concrete and creatures evolved to live in all manner of harsh environments on Earth I have no doubt that there are countless life forms that have developed elsewhere in the cosmos or on other planes of existence.
I hope I live to see the day that there is open contact. As a student of history, I would absolutely be enthralled to learn the stories of civilizations millions of years older than humanity. Just think of all we could learn! One of the main problems we have now is our rudimentary understanding of physics. There's so much more we have to learn. I'm leaning towards believing the multiverse theory is correct. If this is true we're going about space travel and exploration entirely wrong.
Indeed given the right conditions we know that life can survive practically anywhere. Our neurosis comes from the fact that this planet is the only place we can see the right conditions.
I like the multiverse theory, however within that theory there is no actual way of travelling between said universes.
One day, one day . . .
Cg
This is no subject for the ordinary mind and I will say it was well written.
Fermi's paradox is quite interesting and a phrase from it says the argument for intelligent extra-terrestrial life is extremely strong; while the ending part says we have had no concrete evidence of alien life. Though a paradox, that phrase is quite ambigious if you ask me, but in today's context, expecially if you have read the Novel Doomsday Conspiracy by Sidney Sheldon, published in 1991, then you may want to quickly conclude that alien life exist .
If you haven't look for it and please read the last 3 pages detailing how different astronauts who wanted to reveal their space encounters with UFO/aliens died mysteriously. The details of their deaths and the circumstances sorrunding them are quite revealing and disturbing.
Going by the caption below, I strongly agree with Frank J. Tipler and considering the dynamic nature of the universe and it's endless vastness, I wouldn't say the odds are bad, I WOULLD SAY IT IMPOSSIBLE.
To scientists, impossible is nothing so it is worth a try. Who wouldn't want to see man touch the void.
Finally, I strongly believe that we are not alone in this vast and endless universe.
Thank you @cryptogee.
Thank you for your comments, I tried to stay away from the Pandora's Box of alien conspiracy, simply because it offers no concrete evidence. The 'Phoenix Lights' are the closest thing I've seen to possible 'evidence', however even they are inconclusive, we need 'Close Encounters' type evidence before we can say, yay! Definitely aliens! :-)
Cg
I don't think much of this line of thought as it has been neither fruitful nor describable in clear mathematical terms. The math reminds me of the types of economic models that management consultants use: simple in the wrong ways, complex in the others. But whatever, maybe this is interesting to bugmen for good reasons, but I don't see it.
We rely on our 5 senses.... What if there are more senses than we could fathom???? What if the alians are already among us and we are just not aware of their existence due to our limited amount of senses???
What if there is/are other parallel dimensions that we are oblivious of???
The same questions can be asked about alians ability to detect and interact with us....
As per Einstein we have E=mc2
Is it possible that existence is also possible in pure energy state apart from matter...
We human are made of matter, so is it possible that there is some existence made completely of energy???
We human are trying to look beyond the door through a key hole... I don't know if the our existing laws are sufficient to explain every thing... We really don't know anathing beyond the relm that we know of!!!
We even are not close to solving the "Millinium Problems{1 is solved by far} ...
this reminds me of the theory that were all living in a simulation. I guess they are similar concepts.
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