TIMENSIONS

The spacial dimensions are easy to visualize.  A Cartesian Coordinate System  (credited to René Descartes) in three-dimensional space is an ordered triplet of lines (axes), any two of them being perpendicular; a single unit of length for all three axes; and an orientation for each axis. Each axis becomes a number line.

To get from one location to another in the same coordinate system all I need is a direction and distance (vector). In the Cartesian Coordinate System, a vector can be represented by identifying the coordinates of its initial and terminal point. For instance, the points A (x1,y1,z1) and B = (x2,y2,z2) in space determine the free vector AB. 

I intuitively understand and live in a four dimension universe, but for the life of me I can not visualize four dimensions.  But when Susan asks me to meet her somewhere, I get a coordinate for all four of those dimensions (i.e., corner of Brambleton Ave.(x), and Monticello Ave.(y), on the third floor of the old post office (z), at 2:15pm (t), which I promptly forget.  The path I take to get there is not a straight line.  Of course, if I wanted to go from Earth to Mars, then my starting point and my destination move through time and space during my travel interval (requires a little more planning, but still within my Newtonian grasp).

But if I wanted to go see Abraham Lincoln give the Gettysburg Address, then I would need some serious coordinate help.  If I went to Gettysburg, Pennsylvania, I would miss the speech by about 53,861 days.  Not only that, but since the Milky Way Galaxy moves at about 600km/s, Earth has shifted about 2.7 trillion km towards the Great Attractor.  Luckily, Einstein gave us a spacetime coordinate system, so that I can find my way.

A Particle also inhabits a portion of spacetime.  A particle such as a photon 'ocillates', and this action exhibits itself as a frequency.  The frequency of a photon determines its nature.  The electron in the Protium atom 'orbits' the proton (inhabits an electron shell).  The Protium electron has a velocity that is relativistic and should exhibit time dilation, etc.

The  Protium electron oscillates through a field around the proton.
(Simplified in two dimensions)
The electron orbit exhibits a sinusoidal pattern as it moves through time.

Quantum physics tells us that the particle exhibits a wave-particle duality.  There is no reason to doubt that it is a particle of matter, so something else is going on.  The particle has been dimensionalized (phased), and exists in folds of time dimensions.  The particle sets up a wave pattern of 'probabilities'.  They are real, but are called probabilities because they can 'collapse', or dephase, to a point particle when required (Quantum Decoherence).  Decoherence occurs when a system interacts with its environment in a thermodynamically irreversible way.   The timeline that will define our view of the present depends on how we slice the spacetime diagram.

STUFF

THE STUFF THAT STUFF IS MADE OF


Time (what we observe) - a physical quantity that we use to sequence events, and compare intervals between them. Time is also used to define the a of change to quantify motions, work, and force.
Time (what it is) - Time is still not fully understood.  The best predictive models define time as a structure, and is an element of the space-time continuum.  Another model of time holds that time is the geometry of energy, mass, and space.  This implies that 'the present' is the expanding event horizon of an entropy wave (a projection or holographic representation of the workings of the universe), 'the past' is collapsed quantum probabilities, and the future is the steady progression from an ordered to an unordered structure.
Energy (what we observe) - is a quantity that is often understood as the potential of a physical system to do work on other physical systems.
Energy (what it is) - energy arises from conservation of momentum (4-momentum in relativity and momentum of virtual particles in quantum electrodynamics). The conservation of momentum, can be directly derived from homogeneity (=shift symmetry) of space and so is usually considered a fundamental driver of a force.  Some predictive models (i.e., superstring) present fundamental particles (force carriers) that are the purveyors of energy.
Speed of Light- a physical constant, usually denoted by c, and is the maximum speed of the universe. Mathematically it is a vector in one dimensional space equal to one Planck length divided by one Planck unit time.
Mass - Mass is physical representation of energy through time and space. All types of agreed-upon matter exhibit mass, and many types of energy which are not matter—such as potential energy, kinetic energy, and trapped electromagnetic radiation (photons)—also exhibit mass.

Space - (Free Space or Vacuum) - Three dimensional space with no matter. Space and time are closely linked and may be manifestations of the same fundamental construct or geometry.
Matter - has mass and occupies volume (three dimensional space).

THE FORCES THAT MAKE STUFF WORK

Electromagnetism - Electromagnetism is the force that causes the interaction between electrically charged particles.
Gravitation - the force that generates between bodies with a force proportional to the mass.
Strong Interaction - the force that binds the nucleus of an atom together.

Weak Interaction - the force that causes radioactive decay and fusion.



INTERESTING STUFF
  
Hydrogen - The most abundant element in the universe appears to be the hydrogen atom. Hydrogen in its most common isotope, protium, has one proton and an electron.  Niels Bohr predicted a model of the Protium atom with an electron with a stable orbit at a set energy state.  The Bohr model is highly predictive for a system where two charged points orbit each other at speeds much less than that of light, like Protium.

Stylized Bohr Model - Protium Atom

The Protium atom is incredibly small, and we have never seen one.  The things that we believe about atoms come from predictive models that have been developed, and then tested, based on observed behavior of interactions.  

Between 1838 and 1851 Richard Laming, a British surgeon and natural philosopher, hypothesized that there existed sub-atomic particles of unit charge; perhaps one of the first persons ever to do so. He suggested that the atom was made up of a core of material surrounded by concentric shells of these electrical 'atoms', or particles. He was considered as an eccentric. 

A working mathematical model of the atom started developing in the late 1890's and early 1900's. Working with the Ernest Rutherford model derived from the Geiger–Marsden experiment, Niels Bohr developed a quantum physics-based modification of the Rutherford model.  The Bohr model is highly predictive for the protium atom, a single positively charged proton and a negatively charged electron orbital, and related the lines in emission and absorption spectra to the energy differences between the orbits that electrons could take around the atom.

The stylized Bohr Model shown above is the visual representation of the atom that most of us still connect with what an atom looks like (it probably doesn't).  However, it is important to note that if the protium atom were expanded to the scale of the above picture, neither the proton or electron would be visible.  The matter in a protium atom is tiny in comparison to the space it takes up (0.000000000000119%, give or take a decimal or two).

 

Photons - the photon is an elementary particle and has no rest mass and will not decay spontaneously.  The photon can be emitted/absorbed by an atom in transition to a lower/higher energy state, matter/antimatter annihilation, and other energy transitions.  The photon is often described as an energy packet and force carrier for the electromagnetic force.

Electrons - In the Standard Model of particle physics, electrons belong to the group of subatomic particles called leptons, which are believed to be elementary particles.

Wave Function Collapse - Particles, like the photon, can exhibit a wave-particle duality. They are particles, but until they interact, they act like waves. While not main-stream physics, there are theoretical models using Eigenstates of time to yield a solution to this dilemma, showing that the time vectors can set up an interference pattern, but on collapse pinpoints a specific time vector with the particle observed.  All time vectors are equally real until collapse at a point.  Continuous observation of a portion of the field can truncate the wave equation.

WHERE DID THE TIME GO?

Time dilation, as predicted by the Theories of Relativity, is an observed difference of elapsed time between two observers which are moving relative to each other. Say Alex is running very fast with relation to Dana. Alex and Dana will both report back to us that light speed is 186,000 miles per second, and they will both tell us that a beam of light will take the same time from their position to reach point A.

However, Dana will report that Alex's clock is moving very slow, and Alex will report that Dana's clock is moving very fast. Alex will not agree with Dana with regard to the distance from her to point A, and vice versa. To Dana, not only does Alex appear to be moving slowly, but his distance measurements are shorter than hers due to length contraction. Dana and Alex will not always agree on the order of events, so that the relative past and future will not be the same (Relativity of simultaneity).

It is important to tell yourself again that for each observer, the speed of light, time measurement, and distance calculation (amount of space between points) remains the same. So if there were a continuous change to our relative time position, our perception of time would remain consistent, and it would not be noticeable.

ENTROPY

Entropy.  There is a unique connection between time and the second law of thermodynamics.  Entropy is the only quantity in physics that implies a progression - the arrow of time - that leads from now to then.  As time passes, the 2nd Law states that the entropy of an isolated system never decreases.  You could look at entropy as a kind of clock.  The 2nd Law usually implies a loss of heat, or energy, in a system.  You can't make a perpetual motion machine because of the 2nd Law.  But perhaps, if you look at that wild idea of time slowing down - then entropy is more a measure of the time dilation than a loss of energy.


The implication is that the 2nd law pulls us through time.  In Albert Einstein's theories of relativity, time dilation occurs when two observers are in relative uniform motion, one clock appears to move slower than the other.  If we are changing relative position through time, the Lorentz transformation describes how, according to the theory of special relativity, two observers' varying measurements of space and time can be converted into each other's frames of reference. It is named after the Dutch physicist Hendrik Lorentz. It reflects the surprising fact that observers moving at different velocities may measure different distances, elapsed times, and even different orderings of events.


Not such a huge leap to see time as the movement from one relativist point to the next!  Hey, what's the probability of that?  Continuous time evolution of an isolated system that obeys Schrödinger's equation (or Dirac's equation) involves the collapse of the wave function.  Entropy, and the expansion of space, may be the relativistic expression of the 2nd Law.

WHAT IS TIME?

Time is a difficult concept to wrap your head around. We intuitively feel it passing; we can say that time flies, or crawls, or seems to stand still. It can be wasted, squandered, and it can somehow be something on our hands. But what is it? Does it flow like a river? Does it slip like the sand through an hourglass? It certainly never backs up for me. So we sense that time has an arrow, pointing from the past to the future.

However, the laws of physics do not forbid time from 'flowing' backwards. Time symmetry holds for many of the classical variables, including;

• Position of a particle in three-space 
• Acceleration of the particle 
• Force on the particle 
• Energy of the particle 
• Electric potential (voltage) 
• Electric field 
• Electric displacement 
• Density of electric charge 
• Electric polarization 

and others. As a matter of fact, the classical variables that are sensitive to time reversal are those that clearly have a time component built into them; such as, power (rate of work), velocity, and angular momentum.

Arthur Eddington, who coined the arrow of time terminology, concluded that as far as physics goes, the passage of time is merely a property of entropy (more on entropy later). So what is time? The answer is usually two parts philosophy, and one part 'it just is'. Clearly time is needed to get something from here to there, and the passage of time itself is a form of movement that carries us from now to then. From Isaac Newton's aether, to Albert Einstien's space-time continuum, time and space are necessary components of the basic laws, but are never really defined. Is time a something? Is it made out of smaller bits of fundamental goo? What is space? If it is expanding, can it be compressed?

Clearly it is important to our consciousness that time move in one direction, but is it just the part that we sense? Through history, people understood that there were limits to our senses and that sound, and vision, and indeed, the real world around us extended beyond the threshold of our limited perception. We knew that dogs could smell better, hawks and falcons see better, and cats move in the dark.

Most physicists are beginning to believe that time and space do have a finite size, with the smallest time being the Planck time, defined as the time it takes light to travel one Planck length (named after Max Planck). This means that our experience of the world is like watching a cartoon, one Planck slice at a time.

So why the arrow? Why don't the frames flip backwards?

THE EXPANDING UNIVERSE

As predicted by Alexander Alexandrovich Friedman in his solution to the general relativity field equations in 1922, and verified through red-shift observations of distant galaxies by Edwin Hubble in 1929, the universe appears to be expanding.  The Metric Expansion of Space leads to some interesting notions about our perception of reality.  But one of the most interesting concepts to come forward is from José M.M. Senovilla and his team at the University of the Basque Country in Spain.  His team has offered a solution that has time slowing down and disappearing from the universe.  While certainly not main-stream thinking, the proposal offers some insights into the reality of time.

http://www.dailygalaxy.com/my_weblog/2008/01/scientist-says.html
http://www.newscientist.com/article/mg19626354.000-is-time-slowing-down.html