A report on Spacetime and Past

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.
Everything is in the Past (Vassily Maximov, 1889).
Figure 1–4. Hand-colored transparency presented by Minkowski in his 1908 Raum und Zeit lecture
Thoughts of the Past (John Roddam Spencer Stanhope, 1859)
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

The past is the set of all events that occurred before a given point in time.

- Past

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).

- Spacetime
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.

2 related topics with Alpha

Overall
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.

Time

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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.
Horizontal sundial in Taganrog
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.

The physical nature of time is addressed by general relativity with respect to events in spacetime.

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.

Physicists argue that spacetime can be understood as a sort of stretchy fabric that bends due to forces such as gravity.