A report on Time and Past

The flow of sand in an hourglass can be used to measure the passage of time. It also concretely represents the present as being between the past and the future.
Everything is in the Past (Vassily Maximov, 1889).
Horizontal sundial in Taganrog
Thoughts of the Past (John Roddam Spencer Stanhope, 1859)
An old kitchen clock
A contemporary quartz watch, 2007
Chip-scale atomic clocks, such as this one unveiled in 2004, are expected to greatly improve GPS location.
Scale of time in Jain texts shown logarithmically
Time's mortal aspect is personified in this bronze statue by Charles van der Stappen.
Two-dimensional space depicted in three-dimensional spacetime. The past and future light cones are absolute, the "present" is a relative concept different for observers in relative motion.
Relativity of simultaneity: Event B is simultaneous with A in the green reference frame, but it occurred before in the blue frame, and occurs later in the red frame.
Views of spacetime along the world line of a rapidly accelerating observer in a relativistic universe. The events ("dots") that pass the two diagonal lines in the bottom half of the image (the past light cone of the observer in the origin) are the events visible to the observer.
Philosopher and psychologist William James

Time is the continued sequence of existence and events that occurs in an apparently irreversible succession from the past, through the present, into the future.

- Time

The concept of the past is derived from the linear fashion in which human observers experience time, and is accessed through memory and recollection.

- Past
The flow of sand in an hourglass can be used to measure the passage of time. It also concretely represents the present as being between the past and the future.

3 related topics with Alpha

Overall
The Ghost of Christmas Yet to Come shows Scrooge his future in Dickens' A Christmas Carol.

Future

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The Ghost of Christmas Yet to Come shows Scrooge his future in Dickens' A Christmas Carol.
A visualization of the future light cone (at the top), the present, and the past light cone in 2D space.
Project of an orbital colony Stanford torus, painted by Donald E. Davis
Print (c. 1902) by Albert Robida showing a futuristic view of air travel over Paris in the year 2000 as people leave the opera.

The future is the time after the past and present.

The present is a moment in time discernible as intermediate between past and future.

Present

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The present is a moment in time discernible as intermediate between past and future.
A visualisation of the present (dark blue plane) and past and future light cones in 2D space.

The present (or here and now) is the time that is associated with the events perceived directly and in the first time, not as a recollection (perceived more than once) or a speculation (predicted, hypothesis, uncertain).

It is a period of time between the past and the future, and can vary in meaning from being an instant to a day or longer.

Figure 1-1. Each location in spacetime is marked by four numbers defined by a frame of reference: the position in space, and the time (which can be visualized as the reading of a clock located at each position in space). The 'observer' synchronizes the clocks according to their own reference frame.

Spacetime

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Figure 1-1. Each location in spacetime is marked by four numbers defined by a frame of reference: the position in space, and the time (which can be visualized as the reading of a clock located at each position in space). The 'observer' synchronizes the clocks according to their own reference frame.
Figure 1–4. Hand-colored transparency presented by Minkowski in his 1908 Raum und Zeit lecture
Figure 2-2. Galilean diagram of two frames of reference in standard configuration
Figure 2–3. (a) Galilean diagram of two frames of reference in standard configuration, (b) spacetime diagram of two frames of reference, (c) spacetime diagram showing the path of a reflected light pulse
Figure 2–4. The light cone centered on an event divides the rest of spacetime into the future, the past, and "elsewhere"
Figure 2–5. Light cone in 2D space plus a time dimension
Figure 2–6. Animation illustrating relativity of simultaneity
Figure 2–7. (a) Families of invariant hyperbolae, (b) Hyperboloids of two sheets and one sheet
Figure 2–8. The invariant hyperbola comprises the points that can be reached from the origin in a fixed proper time by clocks traveling at different speeds
Figure 2–9. In this spacetime diagram, the 1 m length of the moving rod, as measured in the primed frame, is the foreshortened distance OC when projected onto the unprimed frame.
Figure 2-11. Spacetime explanation of the twin paradox
Figure 3–2. Relativistic composition of velocities
Figure 3-3. Spacetime diagrams illustrating time dilation and length contraction
Figure 3–5. Derivation of Lorentz Transformation
Figure 3–7. Transverse Doppler effect scenarios
Figure 3–8. Relativistic spacetime momentum vector
Figure 3–9. Energy and momentum of light in different inertial frames
Figure 3-10. Relativistic conservation of momentum
Figure 4–2. Plot of the three basic Hyperbolic functions: hyperbolic sine ([[:File:Hyperbolic Sine.svg|sinh]]), hyperbolic cosine ([[:File:Hyperbolic Cosine.svg|cosh]]) and hyperbolic tangent ([[:File:Hyperbolic Tangent.svg|tanh]]). Sinh is red, cosh is blue and tanh is green.
Figure 4-4. Dewan–Beran–Bell spaceship paradox
Figure 4–5. The curved lines represent the world lines of two observers A and B who accelerate in the same direction with the same constant magnitude acceleration. At A' and B', the observers stop accelerating. The dashed lines are lines of simultaneity for either observer before acceleration begins and after acceleration stops.
Figure 4–6. Accelerated relativistic observer with horizon. Another well-drawn illustration of the same topic may be viewed [[:File:ConstantAcceleration02.jpg|here]].
Figure 5–1. Tidal effects.
Figure 5–2. Equivalence principle
Figure 5–3. Einstein's argument suggesting gravitational redshift
Figure 5-5. Contravariant components of the stress–energy tensor
Figure 5–7. Origin of gravitomagnetism
Figure 5–9. (A) Cavendish experiment, (B) Kreuzer experiment
Figure 5-11. Gravity Probe B confirmed the existence of gravitomagnetism

In physics, spacetime is a mathematical model that combines the three dimensions of space and one dimension of time into a single four-dimensional manifold.

2-5) makes the appearance that of two right circular cones meeting with their apices at O. One cone extends into the future (t>0), the other into the past (t<0).