Voyager I has now boldly gone where no man or unmanned spacecraft has gone before, speeding through the outskirts of our solar system on its way to the stars. Launched in 1977, the probe long ago completed its primary scientific mission in close fly-bys of Jupiter and Saturn. Decades later, it continues to send back readings on the heliopause, the boundary between the sun’s magnetic field and the surrounding interstellar medium.
Knowing that Voyager’s trajectory would eventually carry it beyond the solar system, NASA scientists made room for a small repository of cultural material that might be of interest to curious aliens who happened upon the spacecraft. Included along with requisite greetings from world leaders were photographs of various scenes on Earth, as well as sound recordings of nature and music from around the world. It is some measure of how long ago Voyager was launched that these artifacts were encoded on a long-playing phonograph record coated with copper. The record comes with its own stylus and schematic drawings that show how the record is to be played. These might come in handy for aliens unfamiliar with phonographs or, for that matter, for recent-generation earthlings who might otherwise have no idea how to extract data from such ancient technology.
Voyager’s copper-plated record is designed to last for a billion years, which is just as well, since the distances between celestial bodies can be daunting. Even traveling at 38,000 miles per hour – or more than 10 miles per second—the spacecraft would require over 77,000 years to reach Alpha Centuri, the closest star system to us. And since Voyager is not headed in that direction, who knows how long it will take before it ventures into territory frequented by an advanced alien civilization. A billion years wouldn’t be enough time to cross the Milky Way Galaxy, much less reach any of the billions of other galaxies out there. Because the Milky Way is mostly empty space, it is entirely possible that Voyager will never encounter anything at all.
There is as yet no credible scientific evidence of intelligent life outside our solar system. But then, a generation ago there was no evidence of any planets at all outside our solar system, and now hundreds have been catalogued that are close enough to be detected by instruments on earth. It looks like a significant percentage of stars have their own planetary systems, meaning there could be billions of planets in our galaxy alone. This obviously increases the odds that some of them may be Earth-like planets inhabited by creatures that can figure out how to play a phonograph record.
Recently, Yale astronomer Pieter van Dokkun reported the discovery that there were three times as many stars in the universe as anyone imagined, many of them red dwarfs that had previously gone undetected because they were too dim to register on spectrometers. Better readings have yielded an astounding new estimate for the total number of stars in the universe: not 100 sextillion as formerly thought but an even more mind-boggling 300 sextillion, give or take, with a corresponding jump in the number of potentially habitable planets. "There are possibly trillions of Earths orbiting these stars," van Dokkum said. Trillions! And many of these are orbiting red-dwarf stars that are a lot farther along in their life cycle than our sun. This would suggest that any civilizations existing on Earth-like planets might also be a lot farther along than our own. All this is purest conjecture, of course. Nevertheless, it casts a shadow on any exalted notions we might have about occupying a unique place in the cosmos.
But wait – quantum physicists, who look at things through the other end of the telescope, have reported findings that just might cut the universe down to size. Quantum physicists spend their time puzzling over the bizarre behavior of subatomic particles, another realm that is mostly made up of empty space. This is a realm where the laws of classical physics do not apply. To start with, some of those particles also appear to be waves, depending on how they are measured. And until they are measured, they exist in an indeterminate state, neither fish nor fowl, as if they were waiting around to be observed. Even weirder, the act of observing one of two paired (or “entangled”) particles can instantaneously determine the state of the other one as well, even if the two are far apart – a phenomenon that Einstein dismissed as “spooky action at a distance.”
Experiments since Einstein’s day have proven that action at a distance is exactly what is going on at the quantum level, and it doesn’t matter how far apart the particles happen to be when they are observed. Theoretically, they could be on opposite ends of the galaxy or even on opposite ends of the universe. How could these particles instantaneously communicate across such distances? Even traveling at the speed of light, it would take 100,000 years to jump from one end of our galaxy to the other and more than 150 billion years to span the universe. The implications are clear: either signals can travel faster than the speed of light, which is impossible in a universe governed by relativity, or else actions that appear to be separated in time and space are not. “No reasonable definition of reality could be expected to permit this," Einstein and two colleagues wrote in a famous paper challenging so-called quantum nonlocality.
The macroscopic universe of galaxies, stars and planets is a vast debris field left over from a spectacular light show known as the Big Bang. Think of that tiny car in the circus that disgorges all those clowns, except the universe started out even smaller, and it contained all the makings of everything that now exists in space and time, including space and time themselves, all packed into a “singularity” that could pass through the eye of a needle with room to turn around. In its embryonic state, what we now think of as the universe was not many things separated by time and space but one thing governed by quantum rules. And it is starting to look like the universe is still one thing governed by quantum rules, which would explain why entangled particles are able to reach across the universe instantaneously. In effect, there is nothing to reach across. Time and space may turn out to be nothing more than elaborate illusions created by our five senses. The physicist David Bohm likened the macroscopic universe to a hologram that generates the appearance of solid objects in three-dimensional space. Peek behind the curtain of this light show, and you discover a universe that is indivisible and interconnected down to the last subatomic particle. We imagined ourselves to be a mere flyspeck in the vast empty space of the universe when all the while we were safely nestled in the mind of God.