Learning Limits—Part 2

So, returning to the field of science—which is a case of collective knowledge, rather than individual belief: Are we able to describe boundaries to our scientific knowledge that may never be crossed? It may help first to address the difference between knowledge and understanding. My dictionary defines knowledge as “facts, information, and skills acquired by a person through experience or education.” Understanding, however, goes deeper; it involves a person's perception or judgment of a situation. Understanding implies that we perceive the significance of something. There are many scientists who acquire facts and information about a topic, but fail to comprehend their significance. For example, one may collect data on the geological characteristics of some location, without understanding how or why they came about, or what the future may bring.

So if we confine our attention to science, we may ask ourselves if Nature imposes some fundamental limit to what we can know about something. Before the invention of scientific tools such as telescopes and microscopes, we faced an impenetrable barrier to seeing the nature of stars or microorganisms. There seemed to be an absolute boundary to what we could learn. Those barriers were eventually largely surmounted. Today, science seems stumped about what dark matter and dark energy are—yet most scientists do not regard our ignorance in this area as an impenetrable barrier. More experiments and new or improved instruments may solve these quandaries. Better theories and models may point the way.

Cosmologists are posing some of the thorniest questions about the nature of the universe. Some of the questions seem to imply that there might be an outer limit to our knowledge. Does life exist elsewhere? The universe may be so vast and empty that we may never know. Our universe—according to current models—began, as it burst forth from an infinitesimal point, nearly 14 billion years ago. Was there a time before the Big Bang? Our universe—again, according to current theories—has been expanding ever since. Will it continue to expand? Is there anything “beyond” the universe that we inhabit? Some of these queries appear to some cosmologists as to be so fundamental and profound, that they may forever remain beyond the island of our knowledge.

Many of these questions are unanswerable from the perspective of today's knowledge, yet they are definitely worth setting forth. Should we frustratingly and doggedly pursue complex conundrums that are unsolvable? Should we step back, pause, and ask if we are even asking the right questions? Should we grasp at speculative explanations and refuse to acknowledge that we may be in over our heads? Or should we relax, live with the mystery, and let time and accrued wisdom point the way?

Godless Multiverse—Part 2

There is another fascinating aspect to the multiverse idea that some researchers have noted: It not only offers a solution to cosmologists who are exploring different fields of research, but it accords with some ancient religious beliefs. Hindu cosmology describes our current universe as the latest manifestation of periodic cycles of existence. This concept describes how each universe was once born and then dies, followed by the rise of a continuing infinite sequence of universes. Some Buddhist theologies posit the existence of an infinite number of parallel universes, right now. So the Hindu view perceives and infinite string of universes, one after another; while the Buddhist view posits an endless existence of universes—spread across space, rather than time.

In ancient Greece (some 500 years BCE) a few philosophers described an atomistic universe—a very prescient idea, given that the existence of atoms was not verified for another 2500 years or so. Their concept was that our universe—or any universe—is composed of an infinite number of atoms that randomly collide and form the material components of existence. Those Greek atomists were consciously offering an alternative to the then-current view, that gods had created our universe. They especially opposed the practice of people making sacrifices (often human) to the gods, in order to appease them. So here we have a fascinating convergence of a current scientific theory with ancient religious beliefs.

I find it compelling that physicists and theologians are both making assumptions in their explanations of existence that are untestable and even possibly unrealistic. In the case of cosmologists, for example, they assume that the laws of physics that we have discovered in our universe prevail in other universes. We don't know that. (We don't even know if they exist.) We may never know that. Thus, even if the cosmological parameters are allowed to randomly vary, these cosmologists posit the fact that the basic laws of physics must prevail everywhere. That is a debatable assumption.

I find these scientific and theological conjectures fascinating, but also seem to be stemming from a similar place. They both represent humanity's attempts to explain our world, from whatever perspective speaks to each camp. Although religious and scientific points of view have often been at odds with each other, there is some common ground here. Science and religion have feuded for a few hundred years now, and the feud has often become acerbic. It's too bad that each of them can't let go of their narrow perspective and join together in exploring these issues.

Prodigal Planets

Astronomers have made many exciting discoveries in recent years. For example, we now know—thanks to NASA's Kepler space telescope—that our Milky Way galaxy hosts hundreds of billions of planets; a fact that was mere speculation just a couple of decades ago. We also know that far beyond Pluto, our own little solar system contains hundreds of thousands of proto-planets that orbit the sun. (In fact, Pluto itself was recently downgraded to a “dwarf planet,” losing its role in our solar system's eight-member planetary family.)

Many other recent discoveries are being added to the list. For example, the Juno spacecraft now orbiting Jupiter is giving us a far greater understanding of that giant planet. The Cassini mission, now in its 12^th year flying around Saturn, is revealing many discoveries that are changing our understanding of how planetary systems form and what conditions might lead to life in the universe. Black holes have been discovered in far-off galaxies. Gravity waves have been measured. The list goes on. It's an exciting time in the cosmological world.

A new discovery that I will focus on here is the recent finding of free planets that wander alone in our galaxy—unattached to any star; not a part of any solar system. Until recently, the reality of these prodigal planets was, like planets around other stars, mere speculation. But now a few have been observed. It's very difficult to spot these dark wanderers through interstellar space. They cruise through a black void, nearly invisible. Recent advances in telescope technology are allowing us to locate them.

So now we've spotted several of these solitary worlds—enough to give astronomers the confidence that these free-floating planets are quite common. In fact, there are probably hundreds of billions of them wandering alone through the Milky Way.

The mystery: how did they get out there? Aren't planets formed only around stars? In fact, these lonely planets were created in a similar manner to the planets in our own solar system: through a gradual accumulation of bits of rock and dust and gas surrounding a newly-formed star. But then something like a gigantic slingshot action occurred, as one of them gravitationally encountered a huge planet in its solar system, flinging the smaller planet out into space—destined to become a lonely body free of its originating solar system; forlornly meandering through the ages.

Are these prodigal planets destined to be forever lonely and relegated to being just a cold pile of rocks? Could they ever possibly host life? As improbable as it seems, they theoretically could harbor life. Some scientists speculate that, despite having no star to provide warmth, conditions just may be that warm-seeking life could have come into existence in such a forbidden environment. The scenario is completely conjectural, but radioactive decay deep within such a planet could provide the required warmth. Or a thick covering of ice could hold in the necessary heat.

It's all guesswork, but the point is that, before the discovery of these prodigal planets, we had no idea that they even existed. Now we now they do. The fascinating thing is that they conceivably could harbor life. What's more, they are far more accessible to spacecraft from Earth than planets around distant stars, since they float alone, and some of them might be closer than planets still accompanying their star. We would just need to locate a couple of them and send spacecraft out there to investigate.

Who knows what we might find next in outer space? Just a few years ago we had no confirmation that billions of planets are out there in our galaxy. We had no idea that moons of Saturn or Jupiter just might offer conditions conducive to life. Cosmology is advancing at a breathtaking pace. Stay tuned.