Today 02:09 AM
(This post was last modified: Today 02:29 AM by C C.)
https://www.popularmechanics.com/science...m-physics/
EXCERPTS (Vlatko Vedral): For starters—whether or not time is real—we never measure it directly. Instead, we use another physical system called a clock, whose positions actually indicate different moments in time. [...] scientists have since developed even more sophisticated methods, such as atomic clocks; these measure how many times an electron shifts its position within an atom. Typically, this occurs one hundred million billion times per second, providing a reliable tick of about 10 to the power of -16 seconds.
All of the above illustrate the point that we always use the change of state of one system and call this a time measurement. Because time is ultimately a measurement of changes in other systems, rather than a separate entity in its own right, we can eliminate it from all fundamental equations of change in physics.
[...] There is no time, nor is there any flow of it. Everything can be encapsulated by questions of the form...
[...] The same “trick” applies in quantum mechanics. ... we need to assign a correlated state between the system’s positions and the corresponding positions of the clock. In fact, this kind of correlation is called entanglement in quantum mechanics, and it says that once we look at the state of the clock, we immediately know the state of the system.
This approach is known as the Page–Wootters picture, named after Don Page and Bill Wootters, who authored a paper titled “Evolution without evolution” in 1983, proposing this entangled state. They aimed to describe how dynamics arises from the entangled state between the system and the clock, which itself (the entangled state) remains unchanged over time.
[...] The dynamics that emerges at the system level are described by the usual Schrödinger equation (the same Schrödinger of the cat fame, who suggested that, according to quantum mechanics, both dead and alive version of a cat should be able to exist), which is regarded as the most fundamental law of dynamics in physics.
This magical property of quantum timelessness is that different instances of time now become different universes! Time emerges out of entanglement in the same way that the dead and alive cat emerge through entanglement with the decaying atom and the poison in Schrödinger experiment. This is fascinating because the property of being in another universe (say, seeing a living cat instead of a dead one) now becomes equivalent to existing at another time (which, incidentally, we do routinely by just waiting a bit).
What are the main consequences of this extraordinary fact? First of all, it implies that the past and the future exist “at the same time” as the present. In fact, there is nothing special about the moment we call “now” since every instant is a now instant. Likewise, time does not flow; the river of time is not carrying us from the present to the future. Even more interestingly, entering another time just means that your conscious perception is now correlated with the universe’s new state. This means that the “now” could be randomly hopping between different worlds in the quantum entangled state of the universe and we would still perceive the same apparent Schrödinger dynamics as we normally do.
[...] Einstein’s view of the universe aligned with this, and he found great comfort in it. [...] However, an even more intriguing question for a physicist is: what new possibilities could we explore if the universe truly is timeless?
Being a physicist, the most fantastical possibility is this: by performing measurements on the universal clock in a suitable way, we might be able to alter the dynamics of the rest of the universe. Instead of the Schrödinger equation, we could derive a different law of dynamics... (MORE - missing details)
RELATED (use caution, NDE category on the site): Unraveling the Page-Wootters Mechanism
EXCERPTS (Vlatko Vedral): For starters—whether or not time is real—we never measure it directly. Instead, we use another physical system called a clock, whose positions actually indicate different moments in time. [...] scientists have since developed even more sophisticated methods, such as atomic clocks; these measure how many times an electron shifts its position within an atom. Typically, this occurs one hundred million billion times per second, providing a reliable tick of about 10 to the power of -16 seconds.
All of the above illustrate the point that we always use the change of state of one system and call this a time measurement. Because time is ultimately a measurement of changes in other systems, rather than a separate entity in its own right, we can eliminate it from all fundamental equations of change in physics.
[...] There is no time, nor is there any flow of it. Everything can be encapsulated by questions of the form...
[...] The same “trick” applies in quantum mechanics. ... we need to assign a correlated state between the system’s positions and the corresponding positions of the clock. In fact, this kind of correlation is called entanglement in quantum mechanics, and it says that once we look at the state of the clock, we immediately know the state of the system.
This approach is known as the Page–Wootters picture, named after Don Page and Bill Wootters, who authored a paper titled “Evolution without evolution” in 1983, proposing this entangled state. They aimed to describe how dynamics arises from the entangled state between the system and the clock, which itself (the entangled state) remains unchanged over time.
[...] The dynamics that emerges at the system level are described by the usual Schrödinger equation (the same Schrödinger of the cat fame, who suggested that, according to quantum mechanics, both dead and alive version of a cat should be able to exist), which is regarded as the most fundamental law of dynamics in physics.
This magical property of quantum timelessness is that different instances of time now become different universes! Time emerges out of entanglement in the same way that the dead and alive cat emerge through entanglement with the decaying atom and the poison in Schrödinger experiment. This is fascinating because the property of being in another universe (say, seeing a living cat instead of a dead one) now becomes equivalent to existing at another time (which, incidentally, we do routinely by just waiting a bit).
What are the main consequences of this extraordinary fact? First of all, it implies that the past and the future exist “at the same time” as the present. In fact, there is nothing special about the moment we call “now” since every instant is a now instant. Likewise, time does not flow; the river of time is not carrying us from the present to the future. Even more interestingly, entering another time just means that your conscious perception is now correlated with the universe’s new state. This means that the “now” could be randomly hopping between different worlds in the quantum entangled state of the universe and we would still perceive the same apparent Schrödinger dynamics as we normally do.
[...] Einstein’s view of the universe aligned with this, and he found great comfort in it. [...] However, an even more intriguing question for a physicist is: what new possibilities could we explore if the universe truly is timeless?
Being a physicist, the most fantastical possibility is this: by performing measurements on the universal clock in a suitable way, we might be able to alter the dynamics of the rest of the universe. Instead of the Schrödinger equation, we could derive a different law of dynamics... (MORE - missing details)
RELATED (use caution, NDE category on the site): Unraveling the Page-Wootters Mechanism
