Wednesday, February 29, 2012

Hugh Everett: A Man Much Before Of His Time



Duality Of Light: We discovered that all the small particles that collectively construct our world travel through space as probability waves. Instead of traveling from point A to point B like a thrown baseball, today we understand that light behaves in some ways like a solid particle when it interacts with other particles, however, when light travels from place to place, like a wave in an ocean it has no definite position. In fact, even matter particles, such as the particles that make up our bodies, regularly disappear between one position and the next.

Uncertainty Principle: One of the founders of quantum theory, Werner Heisenberg discovered what is now a key principle concerning all quantum behavior. As a particle gives up information about its location, information about its momentum is lost in equal measure. This is called the Heisenberg uncertainty principle, which states that both the position and momentum of a particle cannot be known. The more we know about one, the less we know about the other. So as a rule, whenever a particle assumes a precise position in reality, in that instant it has no momentum. And whenever a particle is moving from one place to another, it has no specific location. Only when the particle interacts with something else does it then establish which physical reality we will experience, but in between interactions the particle exists in another type of reality, a sort of multiplicity where all possibilities are combined together.

Quantum Theory Of Mechanics: Quantum theory was developed near the turn of the century and it wasn’t until 1957 that all the possibilities within each quantum wave led a young graduate student of physics named Hugh Everett III to produce the now famous Many-Worlds Theory as his doctorate thesis. Everett was a student of John Archibald Wheeler, the renowned American physicist and longtime Professor at Princeton. The Many-Worlds Theory makes the simple conclusion that one probabilistic outcome is as real as any other, predicting an immense surplus of many-worlds branch away from each moment of now.

Many Worlds: We can imagine an infinite number of copies identical to our present, but then in the next moment, in each copy there is one single particle that is in a slightly different position than all the others. The denser areas of probability in the interference pattern represent the more probable worlds, while the thin areas represent the least probable worlds. The areas outside the wave pattern that are completely dark can be thought of as worlds outside the realm of quantum possibility.

Reasonable Criticism:
Some scientists shrug at the Many-Worlds Theory and continue to believe there is something that makes quantum reality operate only at the subatomic level, and not at a macrocosmic level where we live. But the technological applications of quantum mechanics to chemistry and electronics have already had a tremendous impact upon society. In addition to television shows and movies where characters cross over into parallel universes, physicists are working toward a complete quantum description of reality. If a complete theory is ever accomplished, it will explain why certain things are possible while others are less so, and it will tell us what is impossible. Presently, the Many-Worlds Theory does not claim that other worlds with different laws and forces of nature cannot exist, but if the probabilities of quantum mechanics were found to be basic to nature then we would reasonably conclude the same laws govern all of existence.

Troubled Private And Professional Life: Hugh Everett was a brilliant mathematician, an iconoclastic quantum theorist and later a successful defense contracter.
He introduced a new conception of reality to physics and influenced the course of world history: the man who invented a quantum theory of multiple universes.

After his new theory of multiple universes met scorn, Hugh Everett abandoned the world of academic physics. He turned to top secret military research and led a tragic private life.
To his children he was someone else again: an emotionally unavailable father; "a lump of furniture sitting at the dining room table", cigarette in hand. He was also a chain-smoking alcoholic who died prematurely in 1982 at the age of 51.

Monday, February 20, 2012

Einstein's Quantum Mechanics: Everett's Parallel Universes







Quantum Mechanics: Broadly speaking, quantum mechanics incorporates four classes of phenomena for which classical physics can not account:
# The quantization of certain physical properties,
# Wave-particle duality,
# The uncertainty principle,
# Quantum entanglement.

The Wave-Particle Duality: It provides a mathematical description of much of the dual particle-like and wave-like behavior and interactions of energy and matter.
The wave-particle duality of energy & matter and the uncertainty principle provides a unified view of the behavior of photons, electrons and other atomic scale objects. Quantum theory states that every particle is everywhere unless the particle is being observed.
An electromagnetic wave such as light could be described as particle-later called the photon-with a discrete quanta of energy that was dependent on it's frequency. This led to a theory of unity between subatomic particles and electromagnetic waves called wave-particle duality in which particle and waves were neither one nor the other, but had certain properties of both.

Albert Einstein's Observation: Physical objects are not in space, but these objects are spatially extended. In this way the concept of empty space loses it's meaning.

Philosophical Interpretations: The Everett many-worlds interpretation, formulated in 1956 holds that all the possibilities described by quantum theory simultaneously occur in a multiverse composed of mostly independent parallel universes. While the multiverse is deterministic, we perceive non-deterministic behavior governed by probabilities, because we can observe only the universe, i.e. the consistent state contribution to the mentioned super position, we inhabit. Everett's interpretation is perfectly consistent with John Bell's experiment and makes them intutively understandable. However, according to the theory of quantum discoherence, the parallel universes will never be accessible to us.

Note:
# Pic 2 from top; Probability densities corresponding to the wavefunctions of an electron in a hydrogen atom possessing definite energy levels and angular momentum.
# Bottom picture; Some trajectories of a harmonic oscillator in a classical mechanics and quantum mechanics.

Saturday, February 4, 2012

Cell: Multicellularity In A New Perspective






Cell: The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. can be classified as unicellular (consisting of a single cell; including most bacteria) or multicellular (including plants and animals). Humans contain about 10 trillion cells. Most plant and animal cells are between 1 and 100 µm and therefore are visible only under the microscope.
The cell was discovered by Robert Hooke in 1665. In 1835, before the final cell theory was developed, Jan Evangelista Purkyně observed small "granules" while looking at the plant tissue through a microscope. The cell theory, first developed in 1839 by Matthias Jakob Schleiden and Theodor Schwann, states that all organisms are composed of one or more cells, that all cells come from preexisting cells, that vital functions of an organism occur within cells, and that all cells contain the hereditary information necessary for regulating cell functions and for transmitting information to the next generation of cells.
The word cell comes from the Latin cellula, meaning "a small room". The descriptive term for the smallest living biological structure was coined by Robert Hooke in a book he published in 1665 when he compared the cork cells he saw through his microscope to the small rooms monks lived in.

Multicellularity in Animals: There are more than 100 visibly distinguishable kinds of differentiated cells in the vertebrate animals. These are organized into issues; the tissues into organs. Groups of organs make up the various systems - digestive, excretory, etc. of the body.

Multicellularity in Plants: Like other organisms, plant cells are grouped together into various tissues. These tissues can be simple, consisting of single cell type, or complex, consisting of more than one cell type. Above and beyond tissues, plants also have a higher level of structure called plant tissue systems. There are three types of tissue systems: dermal tissue system, vascular tissue system and ground tissue system.

An Unique Experiment: An evolutionary transition that took several billion years to occur in nature has happened in a laboratory, and it needed just 60 days.
Under artificial pressure to become larger, single-celled yeast became multicellular creatures. That crucial step is responsible for life’s progression beyond algae and bacteria, and while the latest work doesn’t duplicate prehistoric transitions, it could help reveal the principles guiding them.
“This is actually simple. It doesn’t need mystical complexity or a lot of the things that people have hypothesized — special genes, a huge genome, very unnatural conditions,” said evolutionary biologist Michael Travisano of the University of Minnesota, co-author of a study Jan. 17 in the Proceedings of the National Academy of Sciences.

One Cell in Multicellular Organization: “Multicellularity is the ultimate in cooperation,” said Travisano, who wants to understand how cooperation emerges in selfishly competing organisms. “Multiple cells make up an individual that cooperates for the benefit of the whole. Sometimes cells give up their ability to reproduce for the benefit of close kin.”
The Paramount Factor The new study suggests that environmental conditions are paramount: Give single-celled organisms reason to go multicellular, and they will.

The Future Implications: Targeted breeding of single-celled organisms into complex, multicellular forms could also become a biotechnological production technique.
“If you want to have some organism that makes ethanol or a novel compound, then — apart from using genetic engineering — you could do selection experiments” to shape their evolution, Travisano said. “What we’re doing right here, engineering via artificial selection, is something we’ve done for centuries with animals and agriculture.”

Link for the recent research report in above reference:
http://www.wired.com/wiredscience/2012/01/evolution-of-multicellularity/