Dec 30, 2023 03:00 AM
(This post was last modified: Dec 30, 2023 03:43 AM by C C.)
https://www.iflscience.com/what-is-the-s...nuum-72244
EXCERPTS: . . . In one sense the idea is simple – instead of there being three dimensions of space, with time being something completely different, spacetime is a four-dimensional thing. Events are represented in spacetime by four coordinates: three based on where something occurs, relative to a defined point of origin, and the fourth being the time at which it happens.
[...] The problem most people have with this is that we experience time so completely differently from length, width, and height that the whole thing seems ridiculous. If, for example, we realize we have come too far in a particular direction, we can usually turn around and go back. We wish the same were true for time...
[...] Physicists struggle to explain why time is so different from the other dimensions. Nevertheless, its status as a fourth dimension, albeit a special one, is provable. We also know time is connected to the other three dimensions to the extent that they often can’t be measured accurately without each other.
Under the conditions we experience in our everyday lives, treating space and time as separate isn’t a problem, which is why the idea of spacetime is so counterintuitive. However, if we were traveling at close to the speed of light relative to something important to us, the situation would be very different.
[...] Moreover, this space-time continuum can be distorted, for example, by powerful gravitational forces that affect time as much as they bend space. While controversial when Einstein proposed the idea, it’s now possible to verify the way large masses warp spacetime, for example by comparing clocks in orbit with those on the Earth.
Measurements of the movements of massive objects, such as pulsars, around each other confirm the predictions of General Relativity regarding the workings of spacetime with greater and greater accuracy. These measurements are still being taken, partly because alternative theories to General Relativity exist. However, since these also accept the nature of time as a dimension, and its existence in a continuum with the dimensions of space, even if one of the alternatives is eventually proven superior, it wouldn’t invalidate spacetime... (MORE - missing details)
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H.G. Wells (1895): “Clearly,” the Time Traveller proceeded, “any real body must have extension in four directions: it must have Length, Breadth, Thickness, and—Duration. But through a natural infirmity of the flesh, which I will explain to you in a moment, we incline to overlook this fact. There are really four dimensions, three which we call the three planes of Space, and a fourth, Time. There is, however, a tendency to draw an unreal distinction between the former three dimensions and the latter, because it happens that our consciousness moves intermittently in one direction along the latter from the beginning to the end of our lives. --The Time Machine
Where did Wells get such an idea in 1895, well before Minkowski space?
The occult roots of higher dimensional research in physics (excerpt): Other late-19th-century mathematicians began to imagine the fourth dimension as something far more familiar: the passage of time. The pages of Nature and other scientific journals featured speculations about a four-dimensional amalgam of the three-dimensions of space along with an additional dimension of time.
These notions eventually received a concrete mathematical treatment in Einstein’s general theory of relativity, which enabled physicists to reclaim higher dimensions from the spiritualists. Long before then, though, they left their own imprint on popular culture. H G Wells took note of the idea of a temporal fourth dimension when setting the stage for the Time Traveller’s journey in his novella The Time Machine (1895).
EXCERPTS: . . . In one sense the idea is simple – instead of there being three dimensions of space, with time being something completely different, spacetime is a four-dimensional thing. Events are represented in spacetime by four coordinates: three based on where something occurs, relative to a defined point of origin, and the fourth being the time at which it happens.
[...] The problem most people have with this is that we experience time so completely differently from length, width, and height that the whole thing seems ridiculous. If, for example, we realize we have come too far in a particular direction, we can usually turn around and go back. We wish the same were true for time...
[...] Physicists struggle to explain why time is so different from the other dimensions. Nevertheless, its status as a fourth dimension, albeit a special one, is provable. We also know time is connected to the other three dimensions to the extent that they often can’t be measured accurately without each other.
Under the conditions we experience in our everyday lives, treating space and time as separate isn’t a problem, which is why the idea of spacetime is so counterintuitive. However, if we were traveling at close to the speed of light relative to something important to us, the situation would be very different.
[...] Moreover, this space-time continuum can be distorted, for example, by powerful gravitational forces that affect time as much as they bend space. While controversial when Einstein proposed the idea, it’s now possible to verify the way large masses warp spacetime, for example by comparing clocks in orbit with those on the Earth.
Measurements of the movements of massive objects, such as pulsars, around each other confirm the predictions of General Relativity regarding the workings of spacetime with greater and greater accuracy. These measurements are still being taken, partly because alternative theories to General Relativity exist. However, since these also accept the nature of time as a dimension, and its existence in a continuum with the dimensions of space, even if one of the alternatives is eventually proven superior, it wouldn’t invalidate spacetime... (MORE - missing details)
- - - - - - - - -
H.G. Wells (1895): “Clearly,” the Time Traveller proceeded, “any real body must have extension in four directions: it must have Length, Breadth, Thickness, and—Duration. But through a natural infirmity of the flesh, which I will explain to you in a moment, we incline to overlook this fact. There are really four dimensions, three which we call the three planes of Space, and a fourth, Time. There is, however, a tendency to draw an unreal distinction between the former three dimensions and the latter, because it happens that our consciousness moves intermittently in one direction along the latter from the beginning to the end of our lives. --The Time Machine
Where did Wells get such an idea in 1895, well before Minkowski space?
The occult roots of higher dimensional research in physics (excerpt): Other late-19th-century mathematicians began to imagine the fourth dimension as something far more familiar: the passage of time. The pages of Nature and other scientific journals featured speculations about a four-dimensional amalgam of the three-dimensions of space along with an additional dimension of time.
These notions eventually received a concrete mathematical treatment in Einstein’s general theory of relativity, which enabled physicists to reclaim higher dimensions from the spiritualists. Long before then, though, they left their own imprint on popular culture. H G Wells took note of the idea of a temporal fourth dimension when setting the stage for the Time Traveller’s journey in his novella The Time Machine (1895).
