Life, Uni.verse and Everything
There has been a several decades long debate about whether extra-terrestrial intelligence exists. As more data comes in about the nature of our universe, I think the odds are rapidly approaching 100% in the affirmative.
According to this recent story our universe is at least 78 billion light years radius or 156 billion light years across, minimum. The scientists are quick to point out this minimum size is based soley on a lack of instrument sensitivity, and a mild adjustment in instrument accuracy is likely to push this minimum to at least 192 billion light years across. They also point out the actual size of the universe is probably exponentially much larger.
Some people find these figures confusing since the age of our universe has been pinned down to 13.7 Billion years, or 14.7 Billion years according to this article. So they ask how could the universe expand to a size of at least 78 billion light years radius in only 13.7 billion years? The reason for this rapid early expansion is inflation. The speed of light wasn't violated, as it was the expansion of space itself that exceeded the speed of light.
So how big is our universe?
So huge in fact that I'm going to have to play around with scales so you can get a better idea.
According to the standard inflationary model of cosmology, the visible portion of our universe; the one mapped by our telescopes is an infinitesimally small speck in a much larger universe of at least a 1035 light-year across! I admit this number is really, really big, and almost impossible to imagine. So lets shrink everything down, WAY down, just so we can get a better grasp of it. Let's imagine that the entire universe that we have seen in all the world telescopes, all the galaxies, all trillion of them, extending out 13 billion light years in every direction is shrunk down to the size of a golf ball. Now you are holding the entire visible universe in the palm of your hand. So how big is the actualy 1035 lightyear universe in comparison? If we do a volume calculation, the actual universe contains 1060 of those golf balls! Wow, I guess we didn't shrink things down far enough, but this will have to do. So how big a volume would 1060 golf balls fill up? Try a sphere 850 light years across! So imagine a mass of golf balls that big, and each one of those golf balls contains all the stars and galaxies that we can see through our telescopes.
This is still almost beyond imagining, so lets take a slightly different approach. Imagine you are travelling so fast that you can go from on end of the galaxy to the other in just one second. That's a speed of 100,000 ly/sec. At this speed the entire galaxy would be in reach before you can say the word "go", and wam, you're there. At this speed, you could travel to the nearest galaxy Andromeda in 22 seconds. And you could cross from end of the visible universe to the other in 72 hours. Continuing on at this speed, it would take 115 days to travel a trillion light years, 315 years to travel a quadrillion, and 315,000 years to travel a quintillion or 1018 light years. And yet you have barely moved at all in comparison to the universe which is 1035 light years across. So, lets speed up our warp vehicals again, so that we can travel a quintllion light years every second. At such a speed we could cross the known universe 100 million times in one second. Ok, so now that we are travelling at a speed that might as well be infinite, how long would it take to cross from one side of the univese to the other? 3.7 billion years
Some physicists such as Max Tegmark believe the universe is actually infinite in size. If the galactic density of our own neighborhood is typical across this entire domain, and according to the data from the satellite COBE it is, then our bubble-universe should contain at least another 10100 galaxies. This is such a large figure, that it's difficult to explain it. So to give you an idea of how large a number this is, it's far larger the the number of atoms that compose every object in our own visible universe, which as you remember extends out 13.2 billion light years in every direction. This too is very difficult to conceptualize. So we'll have to scale down even further to a grain of sand. The number of atoms composing a gran of sand is about 1023 atoms, or 100 trillion trillion atoms for each grain of sand on a typical beach. And just think how many grains of sand are on your typical beach, let alone something the size of the Sahara. And that's just on the surface of the earth. All the sand in the world composes much less than 0.00001% of the mass of the earth. The number of atoms composing the Earth is about 1060. And the Earth in turn is one tiny planet around a small star in an ordinary galaxy, among hundreds of billions of galaxies in our very local neigborhood, which we call the visible universe. So 10100 is a very very big number of galaxies! Adding it all together and you get more galaxies in our universe than there are atoms composing every object in our visible universe.
Even if intelligent life is very, very rare, a number as large as 10100 is still likely to produce an abundance of life throughout the universe. A place where countless lifeforms evolve beyond their womb planets into highly advanced space-faring civilizations.
For arguments sake, lets imagine that primitive life happens once in the lifetime of a trillion galaxies, and out of those only one in a trillion ever evolves out of its womb planet into a space-faring civilization. In this example then we are still left with an astounding 1075 advanced societies - more alien cultures than the number of atoms composing planet Earth! Again, for some perspective on such a gargantuan number, there are more advanced civilizations partying it up around the galaxies than there are atoms in every single grain of sand on all the beaches and deserts in the world, and then some. That's more advanced alien civilizations than all the atoms composing our entire solar system!
Assuming life were this rare (and that's very unlikely, even with the Rare Earth Hypothesis), then our nearest star-hopping neighbors would probably be trillions of light-years away. If somehow the speed of light remains a barrier, then we might as well be alone, since we could never make contact with each other before the universe ended. However, I think such barriers will be smashed shortly after the singularity bottleneck. My guess is shortly after a civilization passes through their singularity, the entire universe will be in reach. Already scientists have found loopholes in this light speed barrier. According to Michael Alcubierre, we could hypersurf space-time using exotic matter, allowing the craft to exceed the speed of light by any desirable amount. Then there are traversible wormholes. For an enlightening discussion of some possible scenarios, see Michael C. Price's Some Implications of Traversible Wormholes.
So the problem won't be reaching any part of the universe, that will be childs play. The real challenge will be deciding which parts of the universe to go to. The divide between what is available, and what is conceivable would be enormous! According to Michael Price, the number of civilizations making contact with each other would exceed the ability of any civilization to fathom. According to Price, the implications of such 'Contact' would be staggering, the number of alien cultures would be so large, that it is unlikely anyone could ever catalog all of them, even if they did have computers the size of Jupiter. No historian could encompass the sweep of history, no biologist catalog the species. In a profound sense we'll have returned to a vast ancient world, surrounded by distant lands populated with mythical and fantastic creatures. Construction of a single universal map would be impossible. "If she lost her personal wormhole and forgot her
trans-species designation code (a seventy digit number!)
she would never, ever find her way home again.
None of her descriptions of where she comes from
would relate to anything anyone else knows."
The culture shock of trying to absorb such a vast amount of new data would take close to eternity... an eternity of never ending expansion, novelty and adventure