by Robert Lanza
A single photon hits the detector.
A second photon hits the detector.
A third photon hits the detector.
Somehow, these individual photons add up to an interference pattern!
There has never been a truly satisfactory answer for this. Wild ideas keep emerging. Could there be other electrons or photons “next door” in a parallel universe, from another experimenter doing the same thing? Could their electrons be interfering with ours? That’s so far-fetched that few believe it.
The usual interpretation of why we see an interference pattern is that photons or electrons have two choices when they encounter the double slit. They do not actually exist as real entities in real places until they are observed, and they aren’t observed until they hit the final detection barrier. So when they reach the slits, they exercise their probabilistic freedom of taking both choices. Even though actual electrons or photons are indivisible, and never split themselves under any conditions whatsoever, their existence as probability waves are another story. Thus, what go “through the slit” are not actual entities but just probabilities. The probability waves of the individual photons interfere with themselves! When enough have gone through, we see the overall interference pattern as all probabilities congeal into actual entities making impacts and being observed—as waves.
Sure it’s weird, but this, apparently, is how reality works. And this is just the very beginning of quantum weirdness. Quantum theory, as we mentioned in the last chapter, has a principle called complementarity, which says that we can observe objects to be one thing or another—or have one position or property or another, but never both. It depends on what one is looking for and what measuring equipment is used.
Now, suppose we wish to know which slit a given electron or photon has gone through on its way to the barrier. It’s a fair enough question, and it’s easy enough to find out. We can use polarized light (that is, light whose waves vibrate either horizontally or vertically or else slowly rotate their orientation) and when such a mixture is used, we get the same result as before. But now let’s determine which slit each photon is going through. Many different things have been used, but in this experiment we’ll use a “quarter wave plate” or QWP in front of each slit. Each quarter wave plate alters the polarity of the light in a specific way. The detector can let us know the polarity of the incoming photon. So by noting the polarity of the photon when it’s detected, we know which slit it went through.
Now we repeat the experiment, shooting photons through the slits one at a time, except this time we know which slot each photon goes through. Now the results dramatically change. Even though QWPs do not alter photons other than harmlessly shifting their polarities (later, we prove that this change in results is not caused by the QWPs), now we no longer get the interference pattern. Now the curve suddenly changes to what we’d expect if the photons were particles:
Something’s happened. It turns out that the mere act of measurement, of learning the path of each photon, destroyed the photon’s freedom to remain blurry and undefined and take both paths until it reached the barriers. Its “wave-function” must have collapsed at our measuring device, the QWPs, as it instantly “chose” to become a particle and go through one slit or the other. Its wave nature was lost as soon as it lost its blurry probabilistic not-quite-real state. But why should the photon have chosen to collapse its wave-function? How did it know that we, the observer, could learn which slit it went through?
Countless attempts to get around this, by the greatest minds of the past century, have all failed. Our knowledge of the photon or electron path alone caused it to become a definite entity ahead of the previous time. Of course, physicists also wondered whether this bizarre behavior might be caused by some interaction between the which-way QWP detector or various other devices that have been tried, and the photon. But no. Totally different which-way detectors have been built, none of which in any way disturb the photon, yet we always lose the interference pattern. The bottom line conclusion, reached after many years, is that it’s simply not possible to gain which-way information and the interference pattern caused by energy waves.
We’re back to quantum theory’s complementarity—that you can measure and learn just one of a pair of characteristics but never both at the same time. If you fully learn about one, you will know nothing about the other. And, just in case you’re suspicious of the quarter wave plates, let it be said that when used in all other contexts, including double-slit experiments but without information-providing polarization-detecting barriers at the end, the mere act of changing a photon’s polarization never has the slightest effect on the creation of an interference pattern.
Okay, let’s try something else. In nature, as we saw in the last chapter, there are entangled particles or bits of light (or matter) that were born together and therefore share a wave-function according to quantum theory. They can fly apart—even across the width of the galaxy—and yet they still retain this connection, this knowledge of each other. If one is meddled with in any way so that it loses its “anything’s possible” nature and has to decide instantly to materialize with, say, a vertical polarization, its twin will then instantaneously materialize too, and with a horizontal polarity. If one becomes an electron with an up spin, the twin will too, but with a down spin. They’re eternally linked in a complementary way.
So now let’s use a device that shoots off entangled twins in different directions. Experimenters can create the entangled photons by using a special crystal called beta-barium borate (BBO). Inside the crystal, an energetic violet photon from a laser is converted to two red photons, each with half the energy (twice the wavelength) of the original, so there’s no net gain or loss of energy. The two outbound entangled photons are sent off in different directions. We’ll call their path directions p and s.
We’ll set up our original experiment with no which-way information measured. Except that now we add a “coincidence counter.” The role of the coincidence counter is to prevent us from learning the polarity of the photons at detector S unless a photon also hits detector P. One twin goes through the slits (call this photon s) while the other merely barrels ahead to a second detector. Only when both detectors register hits at about the same time do we know that both twins have completed their journeys. Only then does something register on our equipment. The resulting pattern at detector S is our familiar interference pattern:
This makes sense. We haven’t learned which slit any particular photon or electron has taken, so the objects have remained probability waves.
But let’s now get tricky. First, we’ll restore those QWPs so we can get which-way information for photons traveling along path S.
As expected, the interference pattern now vanishes, replaced with the particle pattern, the single curve.
So far, so good. But now, let’s destroy our ability to measure the which-way paths of the s photons but without interfering with them in any way. We can do this by placing a polarizing window in the path of the other photon P, far away. This plate will stop the second detector from registering coincidences. It’ll measure only some of the photons, and effectively scramble up the double-signals. Because a coincidence counter is essential here in delivering information about the completion of the twins’ journeys, it has now been rendered thoroughly unreliable. The entire apparatus will now be uselessly unable to let us learn which slit individual photons take when they travel along path S because we won’t be able to compare them with their twins—because nothing registers unless the coincidence counter allows it to do so. And let’s be clear: we’ve left the QWPs in place for photon S. All we’ve done is to meddle with the p photon’s path in a way that removes our ability to use the coincidence counter to gain which-way knowledge. (The setup, to review, delivers information to us, registers “hits” only when polarity is measured at detector S and the coincidence counter tells us that either a matching or non-matching polarity has been simultaneously registered by the twin photon at detector
P.) The result:
They’re waves again. The interference pattern is back. The physical places on the back screen where the photons or electrons taking path s struck have now changed. Yet we did nothing to these photons’ paths, from their creation at the crystal all the way to the final detector. We even left the QWPs in place. All we did was meddle with the twin photon far away so that it destroyed our ability to learn information. The only change was in our minds. How could photons taking path S possibly know that we put that other polarizer in place—somewhere else, far from their own paths? And quantum theory tells us that we’d get this same result even if we placed the information-ruiner at the other end of the universe.
(Also, by the way, this proves that it wasn’t those QWP plates that were causing the photons to change from waves to particles, and to alter the impact points on the detector. We now get an interference pattern even with the QWPs in place. It’s our knowledge alone with which the photons or electrons seem concerned. This alone influences their actions.)
Okay, this is bizarre. Yet these results happen every time, without fail. They’re telling us that an observer determines physical behavior of “external” objects.
Could it get any weirder? Hold on: now we’ll try something even more radical—an experiment first performed only in 2002. Thus far, the experiment involved erasing the which-way information by meddling with the path of p and then measuring its twin s. Perhaps some sort of communication takes place between photon p and s, letting s know what we will learn, and therefore giving it the green light to be a particle or a wave and either create or not create an interference pattern. Maybe when photon p meets the polarizer it sends s an IM (instant message) at infinite speed, so that photon s knows it must materialize into a real entity instantly, which has to be a particle because only particles can go through one slit or the other and not both. Result: no interference pattern.
To check out whether this is so, we’ll do one more thing. First, we’ll stretch out the distance p photons have to take until they reach their detector, so it’ll take them more time to get there. This way, photons taking the S route will strike their own detectors first. But oddly enough, the results do not change! When we insert the QWPs to path S the fringes are gone, and when we insert the polarizing scrambler to path P and lose the coincidence-measuring ability that lets us determine which-way information for the S photons, the fringes return as before. But how can this be? Photons taking the S path already finished their journeys. They either went through one or the other slit or both. They either collapsed their “wave-function” and became a particle or they didn’t. The game’s over, the action’s finished. They’ve each already hit the final barrier and were detected—before twin p encountered the polarizing scrambling device that would rob us of which-way information.
The photons somehow know whether or not we will gain the which-way information in the future. They decide not to collapse into particles before their distant twins even encounter our scrambler. (If we take away the P scrambler, the S photons suddenly revert to being particles, again before P’s photons reach their detector and activate the coincidence counter.) Somehow, photon s knows whether the which-way marker will be erased even though neither it, nor its twin, have yet encountered an erasing mechanism. It knows when its interference behavior can be present, when it can safely remain in its fuzzy both-slits ghost reality, because it apparently knows photon p—far off in the distance—is going to hit the scrambler eventually, and that this will ultimately prevent us from learning which way p went.
It doesn’t matter how we set up the experiment. Our mind and its knowledge or lack of it is the only thing that determines how these bits of light or matter behave.
It forces us, too, to wonder about space and time. Can either be real if the twins act on information before it happens, and across distances instantaneously as if there is no separation between them?
Again and again, observations have consistently confirmed the observer-dependent effects of quantum theory. In the past decade, physicists at the National Institute of Standards and Technology have carried out an experiment that, in the quantum world, is equivalent to demonstrating that a watched pot doesn’t boil. “It seems,” said Peter Coveney, a researcher there, “that the act of looking at an atom prevents it from changing.” (Theoretically, if a nuclear bomb were watched intently enough, it would not explode, that is, if you could keep checking its atoms every million trillionth of a second. This is yet another experiment that supports the theory that the structure of the physical world, and of small units of matter and energy in particular, are influenced by human observation.)
In the last couple of decades, quantum theorists have shown, in principle, that an atom cannot change its energy state as long as it is being continuously observed. So, now, to test this concept, the group of laser experimentalists at NIST held a cluster of positively charged beryllium ions, the water so to speak, in a fixed position using a magnetic field, the kettle. They applied heat to the kettle in the form of a radio-frequency field that would boost the atoms from a lower to a higher energy state. This transition generally takes about a quarter of a second. However, when the researchers kept checking the atoms every four milliseconds with a brief pulse of light from a laser, the atoms never made it to the higher energy state, despite the force driving them toward it. It would seem that the process of measurement gives the atoms “a little nudge,” forcing them back down to the lower energy state—in effect, resetting the system to zero. This behavior has no analog in the classical world of everyday sense awareness and is apparently a function of observation.
Arcane? Bizarre? It’s hard to believe such effects are real. It’s a fantastic result. When quantum physics was in its early days of discovery at the beginning of the last century, even some physicists dismissed the experimental findings as impossible or improbable. It is curious to recall Albert Einstein’s reaction to the experiments: “I know this business is free of contradictions, yet in my view it contains a certain unreasonableness.”
It was only with the advent of quantum physics and the fall of objectivity that scientists began to consider again the old question of the possibility of comprehending the world as a form of mind. Einstein, on a walk from The Institute for Advanced Study at Princeton to his home on Mercer Street, illustrated his continued fascination and skepticism about an objective external reality, when he asked Abraham Pais if he really believed that the moon existed only if he looked at it. Since that time, physicists have analyzed and revised their equations in a vain attempt to arrive at a statement of natural laws that in no way depends on the circumstances of the observer. Indeed, Eugene Wigner, one of the twentieth century’s greatest physicists, stated that it is “not possible to formulate the laws of [physics] in a fully consistent way without reference to the consciousness [of the observer].” So when quantum theory implies that consciousness must exist, it tacitly shows that the content of the mind is the ultimate reality, and that only an act of observation can confer shape and form to reality—from a dandelion in a meadow to sun, wind, and rain.
And so, a fourth principle of Biocentrism:
First Principle of Biocentrism: What we perceive as reality is a process that involves our consciousness.
Second Principle of Biocentrism: Our external and internal perceptions are inextricably intertwined. They are different sides of the same coin and cannot be separated.
Third Principle of Biocentrism: The behavior of subatomic particles—indeed all particles and objects—is inextricably linked to the presence of an observer. Without the presence of a conscious observer, they at best exist in an undetermined state of probability waves.
Fourth Principle of Biocentrism: Without consciousness, “matter” dwells in an undetermined state of probability. Any universe that could have preceded consciousness only existed in a probability state.
9
GOLDILOCKS’S UNIVERSE
Wherever the life is, [the world] bursts into appear
ance around it.
—Ralph Waldo Emerson
The world appears to be designed for life, not just at the microscopic scale of the atom, but at the level of the universe itself.
Scientists have discovered that the universe has a long list of traits that make it appear as if everything it contains—from atoms to stars—was tailor-made just for us. Many are calling this revelation the “Goldilocks Principle,” because the cosmos is not “too this” or “too that,” but rather “ just right” for life. Others are invoking the principle of “Intelligent Design,” because they believe it’s no accident the cosmos is so ideally suited for us, although the latter label is a Pandora’s box that opens up all manner of arguments for the Bible, and other topics that are irrelevant here, or worse. By any name, the discovery is causing a huge commotion within the astrophysics community and beyond.
In fact, we are currently in the midst of a great debate in the United States about some of these observations. Most of us probably followed the recent trials over whether intelligent design can be taught as an alternative to evolution in public school biology classes. Proponents claim Darwin’s theory of evolution is exactly that—a theory—and cannot fully explain the origin of all life, which naturally it never claims to do. Indeed, they believe the universe itself is the product of an intelligent force, which most people would simply call God. On the other side are the vast majority of scientists, who believe that natural selection may have a few gaps, but for all intents and purposes is a scientific fact. They and other critics charge that intelligent design is a transparent repackaging of the biblical view of creation and thus violates the constitutional separation of church and state.