Quantum mechanics, in the World of life

Http://news.cnblogs.com/n/509750/

(Shell Translation Learning Group/translation) The gist of the most famous thought experiment in quantum mechanics is that the quantum world is completely different from the world we know. Austrian physicist Erwin Schrodinger (Erwin Schrödinger) Let's imagine a cat in a box. The cat's fate is closely linked to the quantum world, where toxic drugs are placed, but only released when a radioactive atom decays. Quantum mechanics says that before being observed, the atom must be in a unique state-the "superposition state"-in which the atom decays and does not decay. Further, because whether the cat survives depends on the state of the atom, it also means that the cat is in a dead and alive superposition-until someone opens the box to observe it. The life of the cat depends on the state of the atom, and the state of the atom is unresolved.

But no one really believed that the cat could be dead and alive. Atomic particles such as atoms have strange quantum properties (such as having two states at the same time, being in two positions, crossing a barrier that should not be passed through, etc.), and the common classical objects of the cat are not, and there is a very significant difference between them. Why is it? In short, these strange quantum properties are too fragile.

Schrödinger's cat is unlikely to be dead and alive-but will there be other quantum superposition in the body? Image source: egotailor.com

Quantum mechanics stresses that all particles are also waves. But if you want to see strange quantum effects, these waves must be arranged so that the peaks and troughs can be aligned. Physicists call this characteristic "coherence," like a note that is tuned together. If the waves do not overlap, the peaks and troughs will neutralize each other, destroying coherence, and you will not see anything strange. On the other hand, if there is a wave of only one particle, it is easy to keep a tune--just make a line with yourself. But it is almost impossible to arrange the waves of hundreds of, millions of, or even tens of billions of of particles neatly. In this way, these strange things are neutralized inside the big object. That's why there's no certainty about cats.

However, Schrödinger's 1944 book, "What's life", writes that some of the most basic masonry in life, like a radioactive atom invisible to the naked eye, is a quantum entity with counter-intuitive characteristics. In fact, Schrödinger argues that life and non-life are different because life exists in the middle between the quantum world and the classic world-what we can call quantum boundaries.

　　"Orderly birth in order"

Schrödinger's view is based on these seemingly contradictory facts. Although the classical laws-from Newton's Law of mechanics, to the law of thermodynamics, to the law of electromagnetics-appear to be extremely orderly, they are, in fact, based on disorder. Imagine a balloon that is filled with trillions of of gas molecules that are moving in disorder, hitting each other and the inner wall of the balloon. However, when you add and re-average their movement, you get the gas law, which can be used to accurately deduce that the balloon will swell when heated. Schrödinger calls this Law "order in disorder" to illustrate the macro-law, in fact, depends on the particle level of chaos and unpredictable.

So what does this have to do with life? In fact, Schrödinger is very interested in heredity. In the 1944, when Watson and Crick revealed the structure of the DNA molecule for 10 of years, the physical nature of the gene was a mystery. Even so, people already know that genes are going to pass through a generation, and that there is a high degree of fidelity: the probability of error is less than One-zero. It was a mystery, because the genes were already known to be very small-schrodinger believed that genes were too small to rely on the "ordered" laws of "disorder" to ensure the accuracy of their reproduction. He suggested that the process must involve a "more complex organic molecule", in which "every atom, every group of atoms, plays its part".

Schrödinger calls these new structures "aperiodic crystals". He claims that they must obey quantum laws rather than classical rules, and further suggest that genetic mutations may be caused by quantum transitions within crystals. He went on to suggest that many of the characteristics of life may be based on a new physical principle. In the non-living world, as we know, macroscopic laws usually come from disordered molecules: order comes from disorder. But perhaps--Schrödinger says--the macroscopic laws of the world of life reflect something else: the mysterious laws of quantum levels. He called this speculation "orderly from order".

Is he right?

Ten years later, Watson and Crick discovered a double helix structure. The genetic component was originally a single molecule dna--a long chain molecule, which was filled with a base like a bead. It's completely an aperiodic crystal, but it's not called that name. And, as Schrödinger predicts, "every atom" does indeed play "an independent role", and even individual protons exert their quantum properties to determine their respective bases. In the history of science, I'm afraid there are few more prescient predictions. The color of your eyes, the shape of your nose, your character, your intelligence, even the possibility of illness, are encoded at the quantum level.

The aperiodic crystals themselves later became another equally fascinating field. Image source: www.complexphotonics.org

But the new science of molecular Biology, based on Watson and Crick's discoveries, is still largely obsessed with classical physics. This works well in the second half of the 20 world, when biologists and chemists focus on the subject of metabolism, and it is the product of a large number of particles that are based on the principle of order from disorder. But in the 21st century, as biological attention shifted to smaller systems--even the individual atoms and molecules in living cells--the effects of quantum mechanics surfaced again. Recent experiments have shown that some of the most fundamental processes of life are indeed dependent on the peculiar nature of the flow of a quantum undercurrent from reality.

　　From quantum smell to quantum navigation

Let's start with a few relatively marginal examples-such as the sense of smell. The traditional theory of smell is that the scent molecule is detected by a taste receptor, which relies on a key-locking structure in the nose: the scent molecule binds to the void of the receptor and then triggers the reaction, just as the key rotates the lock. This is a delightful, very intuitive doctrine, but it does not explain certain phenomena-for example, molecules with similar shapes often smell differently and vice versa. The revised doctrine argues that receptors may be reacting to molecular vibrations. In the 1996 the idea was further explained at the quantum level--a physicist Luca Du (Luca Turin) suggested that vibrations might promote the quantum tunneling effect of electrons. Open the "lock" of smell. The quantum theory of smell may sound strange, but recently there has been evidence of support: fruit flies can distinguish between identical shapes and only those that use different isotopes of the same element, which is difficult to explain using theories other than quantum mechanics.

Or consider the question: we know that some birds and other animals can navigate by sensing a very faint magnetic field on earth, but how they do it is always a mystery. It is hard to imagine how such a weak magnetic field produces a signal in the animal body. In a further study of Eurasian robins, the bird's navigation system relies on light and differs from the conventional compass, which detects not the direction of the magnetic line, but the angle of the magnetic line relative to the surface. No one knows why.

Until the 1970s, the German chemist Klaus Schuttern (Klaus schulten) found that some of the chemical reactions produced by the particle pair would remain connected, relying on a special quantum attribute-the quantum entanglement. Quantum tangles allow long-distance particles to maintain instant communication, no matter how far apart they are, even if they are thrown at the ends of the Milky Way, they can still be interconnected in an incomprehensible manner. The quantum entanglement is so bizarre that Albert Einstein, who proposes a black hole and a space-time warp theory, himself says it is "a ghostly long-distance effect." But hundreds of experiments have shown that this is true.

Schuttern found that entangled particle pairs are extremely sensitive to the strength and direction of the magnetic field. He thought the mysterious bird navigation might have used the quantum entanglement of particles. Few people agree with this view, but in 2000, Schuttern and his student Sosto Lize (Thorsten Ritz) wrote an influential article that showed how light affects quantum entanglement navigation in the eyes of birds. In 2004, Liz worked with the famous bird Wolfgang and Rossvita Wilkoch, who found convincing experimental evidence that the "ghost" role Einstein had described was true when Eurasia Robins migrated around the world every year.

There is no doubt that navigation and smell are important, but these may not be a core requirement for life on Earth. So let's take a look at what's more important.

　　Electrons and long-eyed light that will teleport.

Let's say enzymes. They are the old ox of the world of life, capable of accelerating chemical reactions and completing a process that takes thousands of years to complete within seconds. Enzymes tend to make the reaction trillions of times times faster, but how it does this is always a mystery. But now, Judith Kranman Judith Klinman of the University of California and Nigel Scrutton of the University of Manchester (Nigel Scrutton) have found that enzymes have a magical quantum trick-tunneling effect. In a nutshell, enzymes promote a process in which the electrons and protons disappear from somewhere in the biochemical molecule, and at the same moment in another place, without having to go through the middle of nowhere-that is, a sense of "transmission."

It's all very basic stuff. Every biological molecule in every cell of every living creature on the planet is created by enzymes. Enzymes are more qualified to be the essential ingredient of life than any other ingredient, even if DNA, after all, can live without DNA. And they are immersed in the quantum world to help us live.

We can also push the argument forward a step further. Photosynthesis is the most important biochemical reaction on earth. It is responsible for transforming light, air, water and a small amount of minerals into grasses, trees, grains and food for plants or herbivores. Initially, the chlorophyll molecule captures light energy. The light energy is converted into electrical energy, which is then transported to a chemical plant called the reaction center, where they are used to fix carbon dioxide and convert it into plant matter. This process of energy transport has long fascinated researchers because it can be so efficient-close to 100%. How does green leaf transport the energy process better than our most advanced technology?

At the University of California, Berkeley, Greheum Fleming Graham Fleming's laboratory has been using "femtosecond spectroscopy" to study the efficiency of photosynthesis for more than more than 10 years. Essentially, the team irradiated lasers on photosynthesis complexes in a very short period of time to find the path to the photon's arrival at the photosynthetic reaction center. As early as 2007, the group studied the FMO complexes in bacteria. In this complex, the energy of the photon needs to pass through a cluster of chlorophyll molecules. It was thought that in this process, photons would jump from one chlorophyll molecule to another, just like charged particles, as Schrodinger's cat might jump from a rock to another while crossing a stream. But this explanation is not entirely clear. Photons do not have a sense of direction, and most of the light should go aimlessly toward the wrong direction and end up in a "stream". However, almost all of the light energy in plants and bacteria that can carry out photosynthesis is transmitted to the photosynthetic reaction center.

When the team fired lasers into the FMO system, they observed strange light echoes-like waves that beat the rhythm. These "quantum drums" mean that the energy of a photon is not passed through a single path into the photosynthetic system, but instead uses quantum coherence to pass through all possible paths simultaneously. Imagine that Schrödinger's cat, in the face of a stream, somehow divides itself into a number of identical, quantum-coherent kittens. They jump over the chlorophyll gravel from all possible routes to explore the quickest route. Now, the quantum drums have been detected in many different light systems, and the light systems of ordinary plants like spinach are no exception. So, in order for us to eat, the most important reaction of the biological community is to use the resources of the quantum world.

If this is not enough for you, let's look at the evolutionary mechanism in the future. Schrödinger believes that mutations may be related to a quantum leap. In the classic DNA article of Watson and Crick, they suggested that genetic mutations might involve the "mutual mutation" of the nucleotide base, which is thought to be related to the quantum tunneling effect. In 1999, Jim Aire-Carilli (Jim Al-khalili) and I felt that proton tunneling might explain a particular type of mutation-the so-called "adaptive mutation". This mutation seems to occur more frequently when the mutation can benefit the individual. Our thesis was purely theoretical, but we are now trying to find experimental evidence for the proton tunneling in DNA. So please wait and see.

In spite of so many quantum interpretations explaining the puzzling phenomena of life, we find ourselves in deeper mysteries. Quantum coherence is an extremely fragile phenomenon, which relies on the unison of particle waves. To maintain quantum coherence, physicists often have to put the system in an almost complete vacuum and cool the system to an absolute 0 degree to stop any heat-driven molecular movement. Molecular vibration is the enemy of quantum coherence.

And if that's the case, why would a creature manage to maintain its molecular order for long enough to perform a quantum trick in a warm, moist cell environment? It's still a deep puzzle. Recent studies have provided a tempting hint that not only do organisms not try to avoid the "storms" of the molecule, they accept them. Mobs are like the captains who use the blast to keep the hull upright and sail towards the right course. As Schrödinger predicted, life is a leisurely voyage along the quantum boundary-the narrow "stream" between the classical world and the quantum world. (Edit: Ent)

Quantum mechanics, in the World of life