Marketing Scoops: Scientists Discovered A Way To Reverse Time And Possibly Erase Mistakes

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In the subatomic universe of quantum physics, you can achieve things considered impossible in our flesh-and-blood physical world. Things like superposition, entanglement, and even teleportation all seem possible when things go quantum. Now, scientists from the Austrian Academy of Sciences (ÖAW) and University of Vienna are adding a kind of time travel to the list………Continue reading….

By: Darren Orf

Source: Popular Mechanics

Critics:

The concept of time can be complex. Multiple notions exist, and defining time in a manner applicable to all fields without circularity has consistently eluded scholars. Nevertheless, diverse fields such as business, industry, sports, the sciences, and the performing arts all incorporate some notion of time into their respective measuring systems.

Traditional definitions of time involved the observation of periodic motion such as the apparent motion of the sun across the sky, the phases of the moon, and the passage of a free-swinging pendulum. More modern systems include the Global Positioning System, other satellite systems, Coordinated Universal Time and mean solar time. Although these systems differ from one another, with careful measurements they can be synchronized.

In physics, time is a fundamental concept to define other quantities, such as velocity. To avoid a circular definition, time in physics is operationally defined as “what a clock reads”, specifically a count of repeating events such as the SI second. Although this aids in practical measurements, it does not address the essence of time. Physicists developed the concept of the spacetime continuum, where events are assigned four coordinates: three for space and one for time.

Events like particle collisions, supernovas, or rocket launches have coordinates that may vary for different observers, making concepts like “now” and “here” relative. In general relativity, these coordinates do not directly correspond to the causal structure of events. Instead, the spacetime interval is calculated and classified as either space-like or time-like, depending on whether an observer exists that would say the events are separated by space or by time.

Since the time required for light to travel a specific distance is the same for all observers a fact first publicly demonstrated by the Michelson–Morley experiment—all observers will consistently agree on this definition of time as a causal relation. General relativity does not address the nature of time for extremely small intervals where quantum mechanics holds. In quantum mechanics, time is treated as a universal and absolute parameter, differing from general relativity’s notion of independent clocks.

The problem of time consists of reconciling these two theories. As of 2025, there is no generally accepted theory of quantum general relativity. Until Einstein’s reinterpretation of the physical concepts associated with time and space in 1907, time was considered to be the same everywhere in the universe, with all observers measuring the same time interval for any event. Non-relativistic classical mechanics is based on this Newtonian idea of time.

Einstein, in his special theory of relativity, postulated the constancy and finiteness of the speed of light for all observers. He showed that this postulate, together with a reasonable definition for what it means for two events to be simultaneous, requires that distances appear compressed and time intervals appear lengthened for events associated with objects in motion relative to an inertial observer. The theory of special relativity finds a convenient formulation in Minkowski spacetime, a mathematical structure that combines three dimensions of space with a single dimension of time.

In this formalism, distances in space can be measured by how long light takes to travel that distance, e.g., a light-year is a measure of distance, and a meter is now defined in terms of how far light travels in a certain amount of time. Two events in Minkowski spacetime are separated by an invariant interval, which can be either space-like, light-like, or time-like. Events that have a time-like separation cannot be simultaneous in any frame of reference, there must be a temporal component (and possibly a spatial one) to their separation.

Events that have a space-like separation will be simultaneous in some frame of reference, and there is no frame of reference in which they do not have a spatial separation. Different observers may calculate different distances and different time intervals between two events, but the invariant interval between the events is independent of the observer and their velocity.

Unlike space, where an object can travel in the opposite directions (and in 3 dimensions), time appears to have only one dimension and only one direction the past lies behind, fixed and immutable, while the future lies ahead and is not necessarily fixed. Yet most laws of physics allow any process to proceed both forward and in reverse. There are only a few physical phenomena that violate the reversibility of time. This time directionality is known as the arrow of time. Acknowledged examples of the arrow of time are:

Radiative arrow of time, manifested in waves (e.g., light and sound) travelling only expanding (rather than focusing) in time (see light cone); Entropic arrow of time: according to the second law of thermodynamics an isolated system evolves toward a larger disorder rather than orders spontaneously; Quantum arrow time, which is related to irreversibility of measurement in quantum mechanics .

According to the Copenhagen interpretation of quantum mechanics; Weak arrow of time: preference for a certain time direction of weak force in particle physics (see violation of CP symmetry); Cosmological arrow of time, which follows the accelerated expansion of the Universe after the Big Bang.

The relationships between these different arrows of time is a hotly debated topic in theoretical physics. The second law of thermodynamics states that entropy must increase over time. Brian Greene theorizes that, according to the equations, the change in entropy occurs symmetrically whether going forward or backward in time. So entropy tends to increase in either direction, and our current low-entropy universe is a statistical aberration, in a similar manner as tossing a coin often enough that eventually heads will result ten times in a row.

However, this theory is not supported empirically in local experiment. Time has historically been closely related with space, the two together merging into spacetime in Einstein’s special relativity and general relativity. According to these theories, the concept of time depends on the spatial reference frame of the observer, and the human perception, as well as the measurement by instruments such as clocks, are different for observers in relative motion.

For example, if a spaceship carrying a clock flies through space at (very nearly) the speed of light, its crew does not notice a change in the speed of time on board their vessel because everything traveling at the same speed slows down at the same rate (including the clock, the crew’s thought processes, and the functions of their bodies). However, to a stationary observer watching the spaceship fly by, the spaceship appears flattened in the direction it is traveling and the clock on board the spaceship appears to move very slowly.

On the other hand, the crew on board the spaceship also perceives the observer as slowed down and flattened along the spaceship’s direction of travel, because both are moving at very nearly the speed of light relative to each other. Because the outside universe appears flattened to the spaceship, the crew perceives themselves as quickly traveling between regions of space that (to the stationary observer) are many light years apart.

This is reconciled by the fact that the crew’s perception of time is different from the stationary observer’s; what seems like seconds to the crew might be hundreds of years to the stationary observer. In either case, however, causality remains unchanged: the past is the set of events that can send light signals to an entity and the future is the set of events to which an entity can send light signals.

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