What is Subconscious Mind ? Mysterious Facts about your Subconscious Mind.

What is Subconscious Mind ?

The unconscious mind (or the unconscious) consists of the processes in the mind which occur automatically and are not available to introspection and include thought processes, memories, interests and motivations.

Mysterious Facts about Subconscious Mind :-

“Whatever we plant in our subconscious mind and nourish with repetition and emotion will one day become a reality.” -Earl Nightingale.

The mind is a many splendored thing. Religions, philosophers, great thinkers, researchers, scientists, psychologists, even esteemed psychonauts, so many have tried their hand at attempting to unravel the complex mysteries of the subconscious and conscious. And while we know plenty, it’s still a great, wondrous mystery that is at the basis of determining each human’s life. Our subconscious mind makes decisions before our conscious mind even knows what’s going on. That’s how invasive it can be, and how critically important it is that we have a better understanding of how our bigger and better half works. Read on to know your own mind better with 30 beneath the surface facts about the subconscious mind.

1) First Things First :-

As per biologists, the brain has 90 billion nerve cells held together by trillions of connection points called synapses. But how powerful is the human brain, really? Scientists suggest a human brain can hold as much information as the Internet did circa 2007. Kind of shocking, considering how often we misplace everyday items, or forget what we ate for dinner last night. This just goes to show how much is at work that we don’t consciously know about.

2) A Broom Closet in a Mansion :-

Try putting this into perspective—we only use 5% of the brain’s capacity for memory, which means the subconscious mind controls the remaining 95%. Even though we don’t know it, our subconscious mind is actively at work whether our conscious mind knows it or not !

3) Kind of like Autopilot :-

Don’t really understand how the subconscious works? Try this – next time you’re typing, try to consciously acknowledge each key you’re typing. It’s tiresome and time-consuming, isn’t it? Notice how when you don’t pay attention, the keys still get typed anyways? That’s the power of the subconscious at work!

4) One Big Bank :-

Your subconscious mind is a ginormous memory bank that has been storing and sorting EVERYTHING that has ever happened to you. By the time a human reaches the age of 21, the amount of data received and stored is 100x the contents of the Encyclopedia Britannica—that’s 32 volumes—32,640 pages of 40 million on half a million topics!

5) So much Bigger :-

The best way to visualize how the conscious and subconscious works is like an iceberg—the conscious being the small part of the iceberg that appears above the water, and the subconscious being the huge part that rests below the water. Conversely, it’s your conscious mind that is the gardener that plants the seeds into the garden or fertile soil that is the subconscious mind. This why the power of positive thinking is so important!

6) Repetition is Key :-

The conscious mind commands, and the subconscious mind obeys. This is where the Law of Attraction comes in – if you keep repeating that positive mantra, the conscious mind may not necessarily believe it—yet—but the subconscious mind will “hear” it and work on getting there.

7) The Power of Positive Affirmation :-

The subconscious knows no time. There is no past or future, simply NOW. Using affirmations with the word now or in present time will help align your subconscious and work for you in the moment. Start thinking about what you want as though you already have it.

8) About Psychedelics :-

Researchers have revealed that the use of LSD (lysergic acid diethylamide) significantly improves language ability by allowing our brains to open up and use them more like a thesaurus. While under the influence of LSD, users are able to easily access related words, proving that the drug enhances the brain’s semantic networks. While engaged in a picture-name task, participants were more likely to make the connection between connected meanings like “hand” instead of “foot”.

9) Some Trippy Stuff :-

Other findings show that LSD brings out a subconscious web of ideas that aren’t conscious, they are closer to awareness, bridging the gap between the two. The drug is able to alter consciousness and makes the brain connect in ways it normally doesn’t.

10) Data Attack :-

According to the Neuro-Linguistic Programming (NLP) model, every single second, humans are bombarded with over 2 million bits of data. It’s the subconscious mind’s duty to help filter through that, otherwise, the conscious mind would be extremely overwhelmed, unable to do its job.

11) Magic Number Seven :-

The subconscious mind goes through this constant barrage of information that is continually being downloaded and sorts through what is necessary at the time, processing 7 chunks of information. This is called “chunking” different groupings of information, rather than one long string of information.

12) A Different Language :-

The results of what the subconscious picks up—the “chunking”—is then communicated to the conscious through images, feelings, sensations, dream and reflexes. The language in which the subconscious communicates is not verbal. There are no words, merely representations.

13) A Picture is Worth a Thousand Words :-

Everything that the subconscious picks up on is through messaging. It speaks in images, feelings and metaphors. It responds to visualizing what you want, but will also communicate back with images and metaphors in the form of dreams, hunches, and songs that “seem” to pop out of nowhere.

14) What You See is What You Get :-

The subconscious mind takes everything literally. This explains why horror movies make us jump in our seats. Or why you’re surprised that the seemingly real picture is—gasp—just Photoshopped.

15) Get 'Em While They 're Young :-

Most of our thoughts and beliefs about the world are formed on a subconscious level, from the ages of 2 to 7 when learning is subconscious. It is at this time that a child’s perceptions of the world are downloaded and formed.

16) Doors of Perception :-

Jim Morrison of The Doors was fascinated with the concept of using art to get in touch with the subconscious mind. He believed in “…a long, prolonged derangement of the senses to attain the unknown… Although I live in the subconscious, our pale reason hides the infinite from us.” Sure dude, whatever you say.

17) Sweet Spot :-

15 minutes before falling asleep, where the mind and body begin to calm down, muscles loosen up and breathing is more relaxed, this is where the brain produces alpha waves. In this 15- minute window between wakefulness and sleep, there are 7-14 electrical waves each second. This is the subconscious mind’s tunnel open to receive messages.

18) Automatic Living :-

Breath is under subconscious control—we forget about it, as it comes naturally to us. Ancient Eastern medicine recognizes the importance of breath work and how breath is the link between the conscious and subconscious mind. When we begin to bring it into the conscious mind, we can become more deeply aware of other parts of ourselves that have been subconscious—this creates mindfulness and is the founding principle of meditation.

19) Shower Thoughts :-

The subconscious mind likes to be left alone, working best when you’re not alert, like when you’re sleeping. Ever notice how good ideas or solutions to problems you’ve been thinking about come to you while watching TV, taking a bath, riding a bus, or going for a walk?

20) Your Life is Determined by Your Unconscious Mind :-

New breakthroughs in the study of epigenetics show that our genes are not necessarily in charge of dictating our inherent traits. It isn’t solely our genes that determine who we are. There are new findings that prove our genes are in fact controlled and manipulated by how our minds perceive and interpret our surrounding environment! This means we have more control over how we can alter many factors about the way we are by the way we interpret events and situations that happen to us.

21) The Power is Yours :-

Dr. Bruce Lipton, former professor of medicine at Stanford University, explains that filtering through things in a more positive way will help to provide a more positive, healthier and better quality of life—regardless of genetic makeup. Attitude, positive or negative, sends messages on a cellular level.

22) Faster Than a Train of Thoughts :-

Our subconscious mind is way ahead of our conscious mind. Studies from the 1970s show that the human brain begins to prepare for action over a third of a second before we consciously decide to act. The bottom line? We think we are making a conscious decision, when in reality, our subconscious mind has already decided for us.

23) Never Let's Go :-

The subconscious mind is always awake and whirring. It’s always working to control your organs and bodily functions while your conscious mind goes to sleep. That being said, your subconscious still picks up on everything, still hearing and processing while in a sleeping state. Listening to relaxing music while sleeping or just before sleeping, being aware of what messaging you expose to yourself before sleeping or just after you awake, is all food for your subconscious mind.

24) The Truth about Ouija :-

A Ouija board is not haunted by ghosts, it’s actually powered by your subconscious. It thrives on what is known as the “ideomotor effect” (ideo from idea or mental representation and motor from muscular action), an example of unconscious, involuntary physical movement that is moving when you’re trying to remain still. That abrupt kickback feeling that awakens you from a deep sleep—AKA the hypnic jerk—is a more aggressive example of the ideomotor effect.

25) What's Really Happening :-

The whole cause and effect of a Ouija board relies on your subconscious. With the setting and the question for the board in place, your brain may create images and memories, causing your body to “override” what the brain consciously tells it to do. Therefore, the muscles in the hands and body will move the pointer to the answer you may subconsciously want to receive.

26) Group Effort :-

And with many people’s hands on the pointer? There’s more possibility of movement. There have been multiple scientific studies showing that blindfolded participants spell way more incoherent messages. Nonsensical words are produced when users cannot spell out from the letters they can see.

27) Getting Your Head in the Game :-

The power of visualization is so strong—especially for athletes—because it programs the subconscious brain. Richard Suinn, an esteemed sports psychologist, first started working with Olympic athletes in 1972 using visualization as part of their training. He studies downhill skiers and found that when he asked them to imagine skiing, electrical signals from the brain were comparable to the signals found when actually physically skiing.

28) The Mind's Eye :-

Another study regarding athletes programming their subconscious was conducted by Guang Yue, an exercise physiologist. He asked volunteers to imagine flexing their biceps. This “visual weight training” happened every day for a few weeks, and afterward, the volunteers showed a 13.5% increase in physical bicep strength. Similar results came from a study at the University of Chicago where participants visualized shooting free throws for a month and improved their shooting by 23%; and a French study showed that long jumpers who spent time visualizing their jumps actually improved the actual motion of the jump 45% of the time.

29) Where the Magic Happens :-

Salvador Dali was fascinated with this special window between being awake and sleeping. In fact, it was at that moment in time that he was able to access and create some of his most famous paintings. His favorite way to make the most of this transitory state was to place a tin plate on the floor and hold a spoon over the plate, while seated in a chair. He would relax his body, entering that dream state and the moment he would fall asleep, the spoon would fall out of his hand and hit the plate, waking him up so that he could record what his subconscious drew up.

30) Feel the Love :-

In the “Love Study” experiment, researchers sought to show the effects one’s thoughts can have on another person. Couples were separated in different rooms, separated by walls of steel. The objective was to see if the participants could transmit thoughts to each other. Both participants were hooked up to to an Electroencephalogram (EEG) and the results showed that people with close relationships or experienced meditators, when directly and intensely sending an intention to each other, could synchronize their brainwaves—no matter the distance. It has been scientifically proven that meditation established more coherent brain waves and biophoton emissions. Other factors that could have helped this work is the belief that the experiment works, the love and compassion for the other, and the intense focus. This just goes to show that people you are close to, can subconsciously receive thoughts.

What is Sensor ?

What is a Sensor ?

There are numerous definitions as to what a sensor is but I would like to define a Sensor as an input device which provides an output (signal) with respect to a specific physical quantity (input).

The term “input device” in the definition of a Sensor means that it is part of a bigger system which provides input to a main control system (like a Processor or a Microcontroller).

Another unique definition of a Sensor is as follows: It is a device that converts signals from one energy domain to electrical domain. The definition of the Sensor can be understood if we take an example in to consideration.

The simplest example of a sensor is an LDR or a Light Dependent Resistor. It is a device, whose resistance varies according to intensity of light it is subjected to. When the light falling on an LDR is more, its resistance becomes very less and when the light is less, well, the resistance of the LDR becomes very high.

We can connect this LDR in a voltage divider (along with other resistor) and check the voltage drop across the LDR. This voltage can be calibrated to the amount of light falling on the LDR. Hence, a Light Sensor.

Now that we have seen what a sensor is, we will proceed further with the classification of Sensors.

Different Types of Sensors :-

We live in a World of Sensors. You can find different types of Sensors in our homes, offices, cars etc. working to make our lives easier by turning on the lights by detecting our presence, adjusting the room temperature, detect smoke or fire, make us delicious coffee, open garage doors as soon as our car is near the door and many other tasks.

All these and many other automation tasks are possible because of Sensors. Before going in to the details of What is a Sensor, What are the Different Types of Sensors and Applications of these different types of Sensors, we will first take a look at a simple example of an automated system, which is possible because of Sensors (and many other components as well).

Classification of Sensors :-

There are several classifications of sensors made by different authors and experts. Some are very simple and some are very complex. The following classification of sensors may already be used by an expert in the subject but this is a very simple classification of sensors.

In the first classification of the sensors, they are divided in to Active and Passive. Active Sensors are those which require an external excitation signal or a power signal.

Passive Sensors, on the other hand, do not require any external power signal and directly generates output response.

The other type of classification is based on the means of detection used in the sensor. Some of the means of detection are Electric, Biological, Chemical, Radioactive etc.

The next classification is based on conversion phenomenon i.e. the input and the output. Some of the common conversion phenomena are Photoelectric, Thermoelectric, Electrochemical, Electromagnetic, Thermooptic, etc.

The final classification of the sensors are Analog and Digital Sensors. Analog Sensors produce an analog output i.e. a continuous output signal with respect to the quantity being measured.

Digital Sensors, in contrast to Analog Sensors, work with discrete or digital data. The data in digital sensors, which is used for conversion and transmission, is digital in nature.

The following is a list of different types of sensors that are commonly used in various applications. All these sensors are used for measuring one of the physical properties like Temperature, Resistance, Capacitance, Conduction, Heat Transfer etc.

Temperature Sensor
Proximity Sensor
Accelerometer
IR Sensor (Infrared Sensor)
Pressure Sensor
Light Sensor
Ultrasonic Sensor
Smoke, Gas and Alcohol Sensor
Touch Sensor
Color Sensor
Humidity Sensor
Tilt Sensor
Flow and Level Sensor

We will see about few of the above mentioned sensors in brief. More information about the sensors will be added subsequently. A list of projects using the above sensors is given at the end of the page.

Temperature Sensor :-

One of the most common and most popular sensor is the Temperature Sensor. A Temperature Sensor, as the name suggests, senses the temperature i.e. it measures the changes in the temperature.

In a Temperature Sensor, the changes in the Temperature correspond to change in its physical property like resistance or voltage.

There are different types of Temperature Sensors like Temperature Sensor ICs (like LM35), Thermistors, Thermocouples, RTD (Resistive Temperature Devices), etc.

Temperature Sensors are used everywhere like computers, mobile phones, automobiles, air conditioning systems, industries etc.

A simple project using LM35 (Celsius Scale Temperature Sensor) is implemented in this project: TEMPERATURE CONTROLLED SYSTEM.

Proximity Sensors :-

A Proximity Sensor is a non-contact type sensor that detects the presence of an object. Proximity Sensors can be implemented using different techniques like Optical (like Infrared or Laser), Ultrasonic, Hall Effect, Capacitive, etc.

Some of the applications of Proximity Sensors are Mobile Phones, Cars (Parking Sensors), industries (object alignment), Ground Proximity in Aircrafts, etc.

Proximity Sensor in Reverse Parking is implemented in this Project: REVERSE PARKING SENSOR CIRCUIT

Infrared Sensor (IR Sensor) :-

IR Sensors or Infrared Sensor are light based sensor that are used in various applications like Proximity and Object Detection. IR Sensors are used as proximity sensors in almost all mobile phones.

There are two types of Infrared or IR Sensors: Transmissive Type and Reflective Type. In Transmissive Type IR Sensor, the IR Transmitter (usually an IR LED) and the IR Detector (usually a Photo Diode) are positioned facing each other so that when an object passes between them, the sensor detects the object.

The other type of IR Sensor is a Reflective Type IR Sensor. In this, the transmitter and the detector are positioned adjacent to each other facing the object. When an object comes in front of the sensor, the sensor detects the object.

Different applications where IR Sensor is implemented are Mobile Phones, Robots, Industrial assembly, automobiles etc.

A small project, where IR Sensors are used to turn on street lights: STREET LIGHTS USING IR SENSORS.

Ultrasonic Sensor :-

An Ultrasonic Sensor is a non-contact type device that can be used to measure distance as well as velocity of an object. An Ultrasonic Sensor works based on the properties of the sound waves with frequency greater than that of the human audible range.

Using the time of flight of the sound wave, an Ultrasonic Sensor can measure the distance of the object (similar to SONAR). The Doppler Shift property of the sound wave is used to measure the velocity of an object.

Arduino based Range Finder is a simple project using Ultrasonic Sensor: PORTABLE ULTRASONIC RANGE METER.

Light Sensor :-

The light sensor is a passive devices that convert this “light energy” whether visible or in the infra-red parts of the spectrum into an electrical signal output. Light sensors are more commonly known as “Photoelectric Devices” or “Photo Sensors” because the convert light energy (photons) into electricity (electrons).

Smoke Sensor :-

Photoelectric alarms (Smoke Sensor) work using a photoelectric sensor and a light source. As smoke enters the chamber and crosses the path of the light beam, light is scattered by the smoke particles, aiming it toward the sensor, which in turn triggers the alarm.

Alcohol Sensor :-

An alcohol sensor detects the attentiveness of alcohol gas in the air and an analog voltage is an output reading. The sensor can activate at temperatures ranging from -10 to 50° C with a power supply is less than 150 Ma to 5V. The sensing range is from 0.04 mg/L to 4 mg/L, which is suitable for breathalyzers.

Touch Sensor :-

Touch sensor is similar to that of a simple switch. When there is contact with the surface of the touch sensor, the circuit is closed inside the sensor and there is a flow of current. ... The measurement circuit will detect the change in the capacitance and converts it into a trigger signal.

Colour Sensor :-

The light sensor works by shining a white light at an object and then recording the reflected colour. It can also record the intensity of the reflection (brightness). Through red, green and blue colour filters the photodiode converts the amount of light to current.

Humidity Sensor :-

A humidity sensor (or hygrometer) senses, measures and reports both moisture and air temperature. ... Relative humidity becomes an important factor when looking for comfort. A sample humidity sensor. Humidity sensors work by detecting changes that alter electrical currents or temperature in the air.

Tilt Sensor :-

A tilt sensor is an instrument that is used for measuring the tilt in multiple axes of a reference plane. Tilt sensors measure the tilting position with reference to gravity and are used in numerous applications. They enable the easy detection of orientation or inclination.

What is Quantum Mechanics ?

What Is Quantum Mechanics?

Quantum mechanics is the branch of physics relating to the very small.

It results in what may appear to be some very strange conclusions about the physical world. At the scale of atoms and electrons, many of the equations of classical mechanics, which describe how things move at everyday sizes and speeds, cease to be useful. In classical mechanics, objects exist in a specific place at a specific time. However, in quantum mechanics, objects instead exist in a haze of probability; they have a certain chance of being at point A, another chance of being at point B and so on.

Three revolutionary principles

Quantum mechanics (QM) developed over many decades, beginning as a set of controversial mathematical explanations of experiments that the math of classical mechanics could not explain. It began at the turn of the 20th century, around the same time that Albert Einstein published his theory of relativity, a separate mathematical revolution in physics that describes the motion of things at high speeds. Unlike relativity, however, the origins of QM cannot be attributed to any one scientist. Rather, multiple scientists contributed to a foundation of three revolutionary principles that gradually gained acceptance and experimental verification between 1900 and 1930. They are:

Quantized properties: Certain properties, such as position, speed and color, can sometimes only occur in specific, set amounts, much like a dial that "clicks" from number to number. This challenged a fundamental assumption of classical mechanics, which said that such properties should exist on a smooth, continuous spectrum. To describe the idea that some properties "clicked" like a dial with specific settings, scientists coined the word "quantized."

Particles of light: Light can sometimes behave as a particle. This was initially met with harsh criticism, as it ran contrary to 200 years of experiments showing that light behaved as a wave; much like ripples on the surface of a calm lake. Light behaves similarly in that it bounces off walls and bends around corners, and that the crests and troughs of the wave can add up or cancel out. Added wave crests result in brighter light, while waves that cancel out produce darkness. A light source can be thought of as a ball on a stick being rhythmically dipped in the center of a lake. The color emitted corresponds to the distance between the crests, which is determined by the speed of the ball's rhythm.

Waves of matter: Matter can also behave as a wave. This ran counter to the roughly 30 years of experiments showing that matter (such as electrons) exists as particles.

Quantized properties?

In 1900, German physicist Max Planck sought to explain the distribution of colors emitted over the spectrum in the glow of red-hot and white-hot objects, such as light-bulb filaments. When making physical sense of the equation he had derived to describe this distribution, Planck realized it implied that combinations of only certain colors (albeit a great number of them) were emitted, specifically those that were whole-number multiples of some base value. Somehow, colors were quantized! This was unexpected because light was understood to act as a wave, meaning that values of color should be a continuous spectrum. What could be forbidding atoms from producing the colors between these whole-number multiples? This seemed so strange that Planck regarded quantization as nothing more than a mathematical trick. According to Helge Kragh in his 2000 article in Physics World magazine, "Max Planck, the Reluctant Revolutionary," "If a revolution occurred in physics in December 1900, nobody seemed to notice it. Planck was no exception …"

Planck's equation also contained a number that would later become very important to future development of QM; today, it's known as "Planck's Constant."

Quantization helped to explain other mysteries of physics. In 1907, Einstein used Planck's hypothesis of quantization to explain why the temperature of a solid changed by different amounts if you put the same amount of heat into the material but changed the starting temperature.

Since the early 1800s, the science of spectroscopy had shown that different elements emit and absorb specific colors of light called "spectral lines." Though spectroscopy was a reliable method for determining the elements contained in objects such as distant stars, scientists were puzzled about why each element gave off those specific lines in the first place. In 1888, Johannes Rydberg derived an equation that described the spectral lines emitted by hydrogen, though nobody could explain why the equation worked. This changed in 1913 when Niels Bohr applied Planck's hypothesis of quantization to Ernest Rutherford's 1911 "planetary" model of the atom, which postulated that electrons orbited the nucleus the same way that planets orbit the sun. According to Physics 2000 (a site from the University of Colorado), Bohr proposed that electrons were restricted to "special" orbits around an atom's nucleus. They could "jump" between special orbits, and the energy produced by the jump caused specific colors of light, observed as spectral lines. Though quantized properties were invented as but a mere mathematical trick, they explained so much that they became the founding principle of QM.

Particles of light?

In 1905, Einstein published a paper, "Concerning an Heuristic Point of View Toward the Emission and Transformation of Light," in which he envisioned light traveling not as a wave, but as some manner of "energy quanta." This packet of energy, Einstein suggested, could "be absorbed or generated only as a whole," specifically when an atom "jumps" between quantized vibration rates. This would also apply, as would be shown a few years later, when an electron "jumps" between quantized orbits. Under this model, Einstein's "energy quanta" contained the energy difference of the jump; when divided by Planck’s constant, that energy difference determined the color of light carried by those quanta.

With this new way to envision light, Einstein offered insights into the behavior of nine different phenomena, including the specific colors that Planck described being emitted from a light-bulb filament. It also explained how certain colors of light could eject electrons off metal surfaces, a phenomenon known as the "photoelectric effect." However, Einstein wasn't wholly justified in taking this leap, said Stephen Klassen, an associate professor of physics at the University of Winnipeg. In a 2008 paper, "The Photoelectric Effect: Rehabilitating the Story for the Physics Classroom," Klassen states that Einstein's energy quanta aren't necessary for explaining all of those nine phenomena. Certain mathematical treatments of light as a wave are still capable of describing both the specific colors that Planck described being emitted from a light-bulb filament and the photoelectric effect. Indeed, in Einstein's controversial winning of the 1921 Nobel Prize, the Nobel committee only acknowledged "his discovery of the law of the photoelectric effect," which specifically did not rely on the notion of energy quanta.

Roughly two decades after Einstein's paper, the term "photon" was popularized for describing energy quanta, thanks to the 1923 work of Arthur Compton, who showed that light scattered by an electron beam changed in color. This showed that particles of light (photons) were indeed colliding with particles of matter (electrons), thus confirming Einstein's hypothesis. By now, it was clear that light could behave both as a wave and a particle, placing light's "wave-particle duality" into the foundation of QM.

Waves of matter?

Since the discovery of the electron in 1896, evidence that all matter existed in the form of particles was slowly building. Still, the demonstration of light's wave-particle duality made scientists question whether matter was limited to acting only as particles. Perhaps wave-particle duality could ring true for matter as well? The first scientist to make substantial headway with this reasoning was a French physicist named Louis de Broglie. In 1924, de Broglie used the equations of Einstein's theory of special relativity to show that particles can exhibit wave-like characteristics, and that waves can exhibit particle-like characteristics. Then in 1925, two scientists, working independently and using separate lines of mathematical thinking, applied de Broglie's reasoning to explain how electrons whizzed around in atoms (a phenomenon that was unexplainable using the equations of classical mechanics). In Germany, physicist Werner Heisenberg (teaming with Max Born and Pascual Jordan) accomplished this by developing "matrix mechanics." Austrian physicist Erwin Schrödinger developed a similar theory called "wave mechanics." Schrödinger showed in 1926 that these two approaches were equivalent (though Swiss physicist Wolfgang Pauli sent an unpublished result to Jordan showing that matrix mechanics was more complete).

The Heisenberg-Schrödinger model of the atom, in which each electron acts as a wave (sometimes referred to as a "cloud") around the nucleus of an atom replaced the Rutherford-Bohr model. One stipulation of the new model was that the ends of the wave that forms an electron must meet. In "Quantum Mechanics in Chemistry, 3rd Ed." (W.A. Benjamin, 1981), Melvin Hanna writes, "The imposition of the boundary conditions has restricted the energy to discrete values." A consequence of this stipulation is that only whole numbers of crests and troughs are allowed, which explains why some properties are quantized. In the Heisenberg-Schrödinger model of the atom, electrons obey a "wave function" and occupy "orbitals" rather than orbits. Unlike the circular orbits of the Rutherford-Bohr model, atomic orbitals have a variety of shapes ranging from spheres to dumbbells to daisies.

In 1927, Walter Heitler and Fritz London further developed wave mechanics to show how atomic orbitals could combine to form molecular orbitals, effectively showing why atoms bond to one another to form molecules. This was yet another problem that had been unsolvable using the math of classical mechanics. These insights gave rise to the field of "quantum chemistry."

The uncertainty principle

Also in 1927, Heisenberg made another major contribution to quantum physics. He reasoned that since matter acts as waves, some properties, such as an electron's position and speed, are "complementary," meaning there's a limit (related to Planck's constant) to how well the precision of each property can be known. Under what would come to be called "Heisenberg's uncertainty principle," it was reasoned that the more precisely an electron's position is known, the less precisely its speed can be known, and vice versa. This uncertainty principle applies to everyday-size objects as well, but is not noticeable because the lack of precision is extraordinarily tiny. According to Dave Slaven of Morningside College (Sioux City, IA), if a baseball's speed is known to within a precision of 0.1 mph, the maximum precision to which it is possible to know the ball's position is 0.000000000000000000000000000008 millimeters.

Onward

The principles of quantization, wave-particle duality and the uncertainty principle ushered in a new era for QM. In 1927, Paul Dirac applied a quantum understanding of electric and magnetic fields to give rise to the study of "quantum field theory" (QFT), which treated particles (such as photons and electrons) as excited states of an underlying physical field. Work in QFT continued for a decade until scientists hit a roadblock: Many equations in QFT stopped making physical sense because they produced results of infinity. After a decade of stagnation, Hans Bethe made a breakthrough in 1947 using a technique called "renormalization." Here, Bethe realized that all infinite results related to two phenomena (specifically "electron self-energy" and "vacuum polarization") such that the observed values of electron mass and electron charge could be used to make all the infinities disappear.

Since the breakthrough of renormalization, QFT has served as the foundation for developing quantum theories about the four fundamental forces of nature: 1) electromagnetism, 2) the weak nuclear force, 3) the strong nuclear force and 4) gravity. The first insight provided by QFT was a quantum description of electromagnetism through "quantum electrodynamics" (QED), which made strides in the late 1940s and early 1950s. Next was a quantum description of the weak nuclear force, which was unified with electromagnetism to build "electroweak theory" (EWT) throughout the 1960s. Finally came a quantum treatment of the strong nuclear force using "quantum chromodynamics" (QCD) in the 1960s and 1970s. The theories of QED, EWT and QCD together form the basis of the Standard Model of particle physics. Unfortunately, QFT has yet to produce a quantum theory of gravity. That quest continues today in the studies of string theory and loop quantum gravity.

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