Posts Tagged universe
In the previous entry in this series of blog posts about the possibility of alien life in our galaxy, and especially about such life visiting us here, I speculated about the wide disparity between the knowledge we’ve obtained about the universe—which is substantial—and our ability to move around in that universe—which is miniscule. We’ve only just gotten to the moon. Is that the reason we’ve never been visited by aliens from other star systems—that the distances are just too immense and space travel is not as easy as our science fiction stories make it out to be? Or is it that they are really nowhere to be found?
There’s certainly no shortage of stars in our galaxy around which planets could form that potentially could harbor life. But before any civilization can visit us here, a lot of things have to happen. It has taken us 2 billion years and several major extinctions for us to reach the sophisticated level we’re at right now. We can see galaxies that are billions of light years away, but we’re a long way in time from journeying there. We’re a long way from visiting even just the nearest star for crying out loud! Any other intelligent civilization almost certainly has to go through that same process of learning about the cosmos before they can make the leap from simply knowing about the presence of other suns out there, to actually visiting them. That’s a huuuuuge step.
So, I’m wondering, how many civilizations out there have actually made that step? Or is there a limit to what a civilization can do?
There’s a hypothesis about alien civilizations that postulates a “Great Filter” that has prevented most if not all civilizations from reaching the ability to travel the galaxy and visit us here on Earth. Somewhere, the Great Filter suggests, in the evolution of a civilization, the inhabitants of a planet reach a stage where their ability to continue is blocked. That’s a legitimate argument, especially as there are at least two processes that could possibly prevent us on Earth from moving on to visit other planets and star systems—annihilation either by nuclear war or by global warming. We haven’t done a particularly good job in reducing the risk from either one lately. But it’s one thing to postulate that, on the one hand, these processes are a risk for us on Earth, and, on the other, transferring those possibilities to other planets. In some respects, the Great Filter seems almost too anthropomorphic, that what happens on Earth must, of necessity, happen on other planets.
One thing we can be sure of, however: that an alien civilization must acquire knowledge about the universe and the galaxy in which we live in order to visit us here, and it must develop the means of transportation around it. But where does that knowledge lie that would allow them to close that gap? Does it exist? Don’t look to science fiction for the answer.
It’s entirely conceivable that a breakthrough will occur in the (near?) (far?) future that will allow us to travel to distant star systems. I’m not ruling that out. And it’s also possible that knowledge is available to any and all civilizations which can reach the highly sophisticated stage where they have access to it. It’s more a question of a civilization being able to make it to that stage. How many civilizations have reached that stage? None? Or does that knowledge even exist? At least that would answer the question: “Where are they?”
This is likely to be the first of three postings on a topic that has intrigued me for several years—the prospect of intelligent life on other planets. Enrico Fermi posed his famous paradox, basically “Where are they?” in 1950. He was referring to the question of why highly intelligent, highly sophisticated visitors from another planet haven’t visited us here on Earth. With the tremendous number of planets out there, say 50 to 100 billion in our galaxy alone, surely the chances must be around 100 percent that other life forms have developed, and a small population should have attained the ability to travel the galaxy in some form of advanced spaceship, perhaps with a drive system we can’t even conceive of. Many planets out there must be older than ours, giving their inhabitants sufficient time to develop space drives that can cut travel time from star to star down to a reasonable value. And that’s what I want to limit my comments to here in this post—the concept of actually travelling the galaxy. Keep in mind, I’m not trying to answer the question of “where are they,” just give some possible reasons why they aren’t.
I want to start by looking at the development of life on Earth and see if we can extrapolate into the future. The Earth is, of course, the only planet we are aware of on which intelligent life has developed, and that could mean it isn’t the best model on which to build an example, but it’s the only one we’ve got so I’m going to use it. Life began on Earth around 2 billion years ago. (There’s some evidence life may have evolved earlier than that, but I’m going to use 2 billion as a nice round number.) In those 2 billion years, life has not once died out completely. There have been extinctions, sure, and large numbers of species have been eliminated, but life has managed to remain continuous in one form or another since then. Even the grand extinction which resulted in the eradication of the dinosaurs around 65 million years ago didn’t completely eliminate all life. Small mammals survived the asteroid impact, and even the dinosaurs themselves were not totally eliminated—they survived into today as birds. Up to that time, reptiles were the dominant animal life form. They were the ultimate, the top level, the upper crust. They basically formed an endpoint, as far as evolution was concerned at that time, and it took an outside event to force a change. Now, I suppose, mammals are the top animal life form. We dominate the planet, and have made changes no other animal could ever conceive of making.
Over the last few thousand years, we humans have learned a lot about the universe in which we exist. We’ve built telescopes which can probe well beyond our own galaxy and see millions of others. We’ve learned what goes on in the interior of a star, in its core, in the atomic and subatomic interactions which produce the light and heat and all the other emissions that the star puts out. We can even detect the faint, wispy neutrinos the star emits. We know there seems to be unseen forces and masses in the galaxy which make up the majority of all mass and energy in it. We’ve seen stars and planets and asteroids, and even planets that just haven’t had quite enough mass to start the fusion reactions that make a star what it is. Behind this has been the development of elaborate mathematics that has made it possible. There’s so much knowledge we’ve accumulated over those several thousand years. All in all, we’re pretty damn astute about our knowledge of the universe and our place in it. We can be proud of that.
Yet, for all our sophistication and knowledge, we’ve never sent humans out into the void of space any farther than the moon. We’ve sent a couple of spacecraft to the edge of our solar system, but those are piddly jumps compared to the size of the universe or even the galaxy. Traveling the galaxy is a hell of a lot harder than looking at it. That’s why science fiction writers have to develop complex, intricate, and ultimately a little naïve spaceships to get their characters around, because there’s no real way to do it. Light travels at the speed of light; we travel at the speed of rocket ships. And the difference is telling.
All this suggests that if there are highly intelligent and sophisticated life forms out there capable of traveling the galaxy, or even from one galaxy to another(!), they would have to have knowledge and space drives so far beyond us they would be impossible for us to conceive. Perhaps harnessing a force we can only guess at. (Read more science fiction for a few good guesses.) Pardon the pun, but even in our sophistication, we’ve got a long way to go.
Back in February, 2017, an interesting article appeared in that month’s issue of Scientific American. Written by Anna Ijjas, Paul J. Steinhardt, and Abraham Loeb, the authors presented some evidence for a “big bounce” in the life of our universe, rather than the much better known “big bang.” The universe as we know it is thought to have started by a rapid inflation of all matter and energy from a point so small it would fit inside an electron with room to spare. Thus the idea of the “big bang” was born, though it was probably a quiet “bang” since there wouldn’t have been any air around to transmit a sound. The authors of the article give some evidence (not overwhelming by any stretch of imagination) that the universe has been alternately expanding from a point, then contracting to another point and expanding again. Ad infinitum.
Well, later several other physicists, thirty-three to be exact, including Stephen Hawking and Alan Guth (who, by the way is the pioneer of the inflation theory) wrote a letter stating their opposition to the evidence in the article, and reaffirming their belief that the universe started with one and only one big bang. Their evidence is that the universe is not only expanding, but is expanding at an ever increasing rate, and either already has or soon will reach a “point of no return” where it can only continue to expand, and never will contract. Too much dark energy pushing the matter in the universe apart. It’ll go on forever.
Two competing theories. I emphasize that the Scientific American article did not state that the authors thought the Big Bang theory was wrong, just that they thought it did not explain everything, and a rebounding universe was a possibility. Okay, so much for that.
My interest in this discussion between the “Uni”-verse theory and the “Multi”-verse theory isn’t to try and distinguish between them, or even try to add my name to one or the other. I’m not a physicist and haven’t got the faintest idea which is correct. I’ll let those more competent than I figure that out. But as I began to think about the concept of a rebounding universe, my thoughts took a philosophical turn, and I began to wonder where we all fit in such a scenario. The universe expands from a point source and grows larger and larger, to eventually result in our galaxy, our solar system, our planet, our cities and towns, and us. It goes on for billions of more years, and reaches a tipping point. It begins to contract and drops back to a point, and the cycle starts all over again. All of that is conceivable by the human mind. But what isn’t conceivable is the idea that this has been going on forever, and will go on into infinity. Back in 2010, I wrote a blog called “Wrap Your Mind Around This…” in which I pointed out a few examples of things that are so out of the ordinary in today’s world that they were impossible for the human mind to comprehend. This rebounding universe is another. (See the earlier blog at https://rogerfloyd.wordpress.com/2010/08/08/wrap-your-mind-around-this/) Although I can see a universe that starts with an inflation and continues on only to dissipate into infinity, I can’t begin to envision a universe that bounds and rebounds, like a tennis ball that will not stop bouncing. Such a universe violates the laws of physics. The most difficult part to envision is that there has never been a beginning, and there will never be an end. How does something never have a beginning?
I wonder, does the universe play the same thing over and over with each rebound? Did we exist in all those past universes? Or, is each universe different?
The universe in which we currently exist is so large, we are almost infinitely tiny in comparison. Our galaxy, which is so much larger than us, is itself only one of billions, even, perhaps, trillions. But to put all that in the context of a universe that rises and falls like a bouncing ball, and has been going on forever—no beginning, no end—just makes the comparison even more difficult to understand.
The title of this post isn’t meant to ask where you are in a spatial location, but in terms of time. Where are you—where are we all, for that matter—in the life of this universe? I’ve been thinking about this for a long time. We all live on a rather attractive blue, white, green and brown planet circling a rather ordinary yellow-white star in a rather ordinary galaxy somewhere in the middle of billions of other galaxies which together constitute what we affectionately refer to as the “universe.” This universe arose from a massive expansion of all matter and energy some thirteen billion years ago, and is rapidly expanding and expanding, apparently to go on forever, driven apart by wild forces within itself. It will go on for time immemorial, never to return to its original state. That’s, at least, the current thinking.
Here we are, sophisticated, sentient human beings, watching this all unfold, trying to make sense of it. I’ve wondered, ever since I heard of the “big bang” hypothesis, which is the current favorite explanation of how we got here, if there isn’t an alternative explanation, that the universe will eventually run out of steam and collapse back onto itself in a sort of “big crunch,” or “big splat,” from which it would rebound into another expansion and another universe, and so on, ad infinitum. That seems to me to be a more logical way for the universe to run than just one “bang” which blows up like a balloon and dissipates out in the nether regions, never to be seen again. The “single bang” theory doesn’t explain what came before the expansion, nor what will come after it. But that may be the way it really is. Dark energy seems to be pushing the galaxies apart faster than dark matter can keep them together.
Philosophically, this is mind boggling. We are the only species on this planet that really understands, to any degree whatsoever, the goings-on out there in space. We’ve been watching the skies for thousands of years. We’ve sent satellites into orbit to observe it. We’ve sent men to the moon. Do you think that cat or dog or goldfish or parakeet in your house cares much about the big bang? Do the deer and the wolves in the forest understand that the little red dot in the sky is a cold, solid planet rather than a blazingly hot star? Or even what a star is in the first place? No, just us. Yet we humans make up such a miniscule percentage of the universe, it’s difficult to estimate how many zeros I’d have to put down to the right of a decimal point to give that percentage. We humans are what I might call “universe sentient.” We know where we are, though we can’t travel very far in it. We’ve seen the stars, the Milky Way, and some of the other galaxies that make up our universe. We have a lot to learn, granted. But we are capable of learning it. We have the mathematical skills and computer skills to master the intricacies of the universe. No dog or cat, or even chimpanzee, has that. Most likely, other civilizations exist in our galaxy with similar skills, perhaps even more advanced. (Maybe they can tell us if dark matter and dark energy really exist.) But philosophically we are alone, and, I suspect, will remain alone for the foreseeable future.