In earlier posts, I talked about the significance of quantum mechanics to our technology advancements and reviewed the book- Quantum Enigma. However, I missed the most important point; I didn't explain how exactly quantum mechanics is contrary to our common senses. I'll try my best to keep the explanation short and simple, so even I could understand it. If you don't like to read (at least watch the cartoon), skip to the last part where I list what the quantum mechanics is strongly suggesting.
OUR COMMONSENSE BELIEF = CLASSICAL PHYSICS
Classical physics, some call it "Newtonian physics", has five basic assumptions about the fabric of reality: reality, locality, causality, continuity, and determinism. These assumptions were rested within a framework of an absolute fixed space and time.
The assumption of reality refers to the idea that the physical world is objectively real. Meaning that it exists independently of any observation. The moon is still there even when nobody is looking at it. Locality refers to the idea that the only way that an object can be influenced is through direct contact with another object.
Causality assumes that time only moves in one direction, thus the cause-effect sequences are absolutely fixed. Future events cannot affect past events. Continuity assumes that there are no discontinuous jumps in nature. Determinism assumes that things progress in an orderly, predictable way. It assumes that if we know every factor, we can predict the future with 100% certainty.
Still with me? If you take all these assumptions for granted, congratulations; you got commonsense.
Long story short, when we studied matter in a very very very small scale, it was discovered that matter has both particle and wavelike properties; wave–particle duality. Particles are like billiard balls; separate objects with specific locations in space. While waves are like ripples in water. They are not localized in space but spread out, they are soft in that they can interpenetrate and interfere with each other without harm. Werner Heisenberg formalized the wave-particle relationship in his uncertainty principle,
The more precisely the position of a particle is determined, the less precisely its momentum is known, and vice versa.Let me rephrase this: matter behaves like particles AND wave; it's in a specific location AND it's spread out; it's separated AND it's not. With this complementary nature, it's fundamentally impossible to know both the position and momentum of a particle. The more you look at its particle-like properties, the less you know about its wavelike properties, and vice versa. Since we cannot know all of the present properties of a particle, the future cannot be known, even in principle.
Now before you start saying how it's impossible, there's a experiment to demonstrate all this. And it does more than demonstrating the wave-particle duality, so much more. Watch the cartoon below for a basic double-slit experiment and then continue reading.
Basically, even if you shoot individual photons one at a time through the apparatus, you'll end up with that same interference pattern that you saw when shot a flood of photons through the screen. This means that each individual photon goes through both slits at the same time, behaving like a wave. It was interfering with or was entangled with itself (See Quantum entanglement). However, when we look at which slit it actually goes through, the photon acts like particles instead, going through one slit; our observation alone causes a wave function collapse. We never actually observe a photon as a wave; it just acts that way when we're not looking! This puzzle is what we call the measurement problem.
If you add an extremely fast shutter in front of one of the slits, so you can open or close it after the photon has gone through the slit but before it has been captured by the camera. When you fire a single photon at the apparatus and measure where it lands, sometimes the slit is open and sometimes closed. What you find is that even though the decision to open or close the slit was made after the photon had already gone through one or both slits, the resulting behavior is like a particle if one slit is closed and like a wave if both slits remain open. Somehow the photon "knows" after it had already gone past the slits that one of them would be closed later. Physicist John Wheeler proposed this experiment and dubbed it a "delayed-choice" design. Not only is the photon entangled with itself in space, but also in time.
Now to make it truly mind-bending, there is something called the delayed choice quantum eraser. In simple terms, after the experiment is finished and the photon's position is already recorded, the experimenter can still decide whether that photon had passed through one slit or both slits!
CONSCIOUSNESS AND FREEWILL
In classical physics, objects are regarded as objectively real and independent of the observer. In the quantum world, this is no longer the case. As physicists Bruce Rosenblum and Fred Kuttner (authors of the book- Quantum Enigma) put it,
If we assume that no observable physical phenomena exist other than those specified by the present quantum theory, a role for the observer in the experiment can be denied only at the expense of challenging the belief that the observer makes free choices.In other words, the experimenter's choice of whether to keep one of the slits open or closed changes how the photon behaves. This effect of our choice does not depend on the objects used. Any quantum object would show the same results, and given that all physical objects are already quantum objects, this is a general question not just limited to the microscopic world. According to Rosenblum and Kuttner, an experimenter must conclude that:
Reality was somehow created by the observation itself, that the observed reality is created solely by the observer's acquisition of knowledge. If so, the observer is inseparably involved with the observed system. That would challenge his view of a physically real world existing independently of his senses perceiving it. The only alternative the experimenter sees to this observer-involved reality is to question his ability to freely choose the experiment.Some neuroscientists consider the quantum world as irrelevant to their concern and therefore do not attempt to understand the concept. However, "the exact values accounting for what in classic physics models are called ‘dynamic effects of noise’ are unknowable in principle. The contemporary physical model accounts for these uncertainties in brain dynamics" (Quantum physics in neuroscience and psychology) In other words, the quantum physics explains our brain better than the classical physics (See quantum brain dynamics). As Pascual Jordan, one of the principal mathematical architects of quantum theory, points out regarding the delayed choice quantum eraser:
Observations not only disturb what has to be measured, they produce it....We compel [the electron] to assume a definite position....We ourselves produce the results of measurement.
Some scientists thought that the unusual results of the double-slit experiment were due to some hidden variables. This speculation was destroyed by Bell's theorem. Its experiment basically confirmed that the quantum theory is correct and that no physical theory of local hidden variables can ever reproduce all of the predictions of quantum mechanics.
Furthermore, quantum theory's prediction of the strength of interactions between an electron and a magnetic field has been experimentally confirmed to a precision of two parts in a trillion. So the problem is not if the quantum theory being true or not, but rather what does it really means.
DEBUNKING THE FIVE ASSUMPTIONS OF CLASSIC PHYSICS
Reality: An absolute reality independent of us fades like the Cheshire Cat because we now know that fundamental properties of the world are not determined before they are observed. An unobserved reality is radically different than the one we see.
Locality: The fact that quantum objects can become entangled (See Quantum entanglement) means that the common sense assumption that ordinary objects are entirely and absolutely separate is incorrect. In unobserved states, quantum objects are connected instantaneously through space and time.
Causality: The assumption of causality collapses as Albert Einstein's theory of relativity revealed that the fixed arrow of time is an illusion. We now know that the arrow of time depends on the perspective of the observers.
Continuity: At small scales, space and time are neither smooth nor contiguous
Determinism: This one is dissolved by itself as it relies on the assumptions of causality, reality, and certainty.
WHAT THE QUANTUM MECHANICS IS STRONGLY SUGGESTING
- True probability exists (See probability theory): In unobserved states, the photon is in a superposition state. In other words, when you flip a coin, it's both head and tail until you (or something) look at it. The probability of head or tail is not us being ignorant of the result, but it's actually being 50% head and 50% tail when it's unobserved; both and neither.
- The future is uncertain
- Freewill exists
- Consciousness affects matter
- The arrow of time depends on the perspective of the observers (the present could affect the past; see delayed choice quantum eraser)
- Our common sense of the objective reality is WRONG
Entangled Minds by Dean Radin
Quantum physics in neuroscience and psychology: a neurophysical model of mind–brain interaction
Quantum Enigma by Bruce Rosenblum and Fred Kuttner
What's even more interesting is that with this new understanding of reality, concepts like parallel universes and higher dimensions are now conceivable and possibly true (See the book, Parallel Worlds). Listen how Michio Kaku explains the string theory in the video below.