# Spacetime......Just the graph?

Discussion in 'Pseudoscience' started by The God, Jan 18, 2016.

1. ### The GodValued Senior Member

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If I recall correctly the great Einstein himself said that a scientific theory should be easily explainable to a layman in simple language.....None could disagree with that.

Few recent threads had certain discussion on spacetime, lot of confusion and arguments over the simple question..what is the spacetime, is it real ? Is it physical ? or it is just the mathematical stuff ? No consensus at least on this forum.

In this thread at a later point I wish to get into a novel idea about spacetime, but for time being, I wish to present a simple layman type definition of spacetime, which will make Einstein happy.

Spacetime is like your 'timeline' in facebook account. From the day you are born, you mark your position on a globe with time stamp, then keep updating your position as you grow, you will get a (position+time) graph, that is the spacetime. So it is just the time stamped plot of your position in the space as you move under the influence of Gravity.

To be contd...

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https://einstein.stanford.edu/content/relativity/q411.html

What is a space time continuum?

In 1906, soon after Albert Einstein announced his special theory of relativity, his former college teacher in mathematics, Hermann Minkowski, developed a new scheme for thinking about space and time that emphasized its geometric qualities. In his famous quotation delivered at a public lecture on relativity, he announced that,

"The views of space and time which I wish to lay before you have sprung from the soil of experimental physics, and therein lies their strength. They are radical. henceforth, space by itself, and time by itself, are doomed to fade away into mere shadows, and only a kind of union of the two will preserve an independent reality."

This new reality was that space and time, as physical constructs, have to be combined into a new mathematical/physical entity called 'space-time', because the equations of relativity show that both the space and time coordinates of any event must get mixed together by the mathematics, in order to accurately describe what we see. Because space consists of 3 dimensions, and time is 1-dimensional, space-time must, therefore, be a 4-dimensional object. It is believed to be a 'continuum' because so far as we know, there are no missing points in space or instants in time, and both can be subdivided without any apparent limit in size or duration. So, physicists now routinely consider our world to be embedded in this 4-dimensional Space-Time continuum, and all events, places, moments in history, actions and so on are described in terms of their location in Space-Time.

Space-time does not evolve, it simply exists. When we examine a particular object from the stand point of its space-time representation, every particle is located along its world-line. This is a spaghetti-like line that stretches from the past to the future showing the spatial location of the particle at every instant in time. This world-line exists as a complete object which may be sliced here and there so that you can see where the particle is located in space at a particular instant. Once you determine the complete world line of a particle from the forces acting upon it, you have 'solved' for its complete history. This world-line does not change with time, but simply exists as a timeless object. Similarly, in general relativity, when you solve equations for the shape of space-time, this shape does not change in time, but exists as a complete timeless object. You can slice it here and there to examine what the geometry of space looks like at a particular instant. Examining consecutive slices in time will let you see whether, for example, the universe is expanding or not.

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http://www.daviddarling.info/encyclopedia/S/spacetime.html
The union of space and time into a four-dimensional whole. More precisely, the inseparable four-dimensional manifold, or combination, which space and time are considered to form in the special and general theories of relativity. In the absence of a gravitational field, spacetime reduces to Minkowski space.

A point in spacetime is known as an event. Each event has four coordinates (x, y, z, t). Just as the x, y, z coordinates of a point depend on the axes being used, so distances and time intervals, which are invariant in Newtonian physics, may depend, in relativistic physics, on the reference frame of an observer; this can lead to bizarre effects such as length contraction and time dilation. A spacetime interval between two events is the invariant quantity analogous to distance in Euclidean space. The spacetime interval s along a curve is defined by the quantity

ds2 = dx2 + dy2 + dz2 - c2dt2
where c is the speed of light. A basic assumption of relativity theory is that coordinate transformations leave intervals invariant. However, note that whereas distances are always positive, intervals may be positive, zero, or negative. Events with a spacetime interval of zero are separated by the propagation of a light signal. Events with a positive spacetime interval are in each other's future or past, and the value of the interval defines the proper time measured by an observer traveling between them.

On ultramicroscopic scales, the quantum nature of spacetime would become apparent and require a quantum theory of gravity to describe it.

7. ### The GodValued Senior Member

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This is the seed for present confusion...if you take away two real things...space and time....and make it spacetime....then you are bound to create an impression of some kind of reality to new entity 'spacetime'......however unreal the spacetime may be.

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The only confusion I see is yourself in believing you are ever going to rewrite what 100 years of physics has already accepted.

9. ### The GodValued Senior Member

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May be who knows, lets stick to OP, let it build up...

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My own definition?
Spacetime is simple the geometric framework against which we calculate GR and in which we exist. It exists to show time as the fourth dimension and its relationship with space, both which we now know to be variable, dependent on one's Frame of reference.
Space exists: It stops everything being together. Time exists; It stops everything from happening together. Therefor spacetime exists.

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Which would encompass what we already know as GR.

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You have it arse up: Logically, if you take to real things, space and time, put them together, you have the one reality of four dimensional spacetime

"The views of space and time which I wish to lay before you have sprung from the soil of experimental physics, and therein lies their strength. They are radical. Henceforth space by itself, and time by itself, are doomed to fade away into mere shadows, and only a kind of union of the two will preserve an independent reality".
Herman Minkowski:

13. ### PhysBangValued Senior Member

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This is a spectacularly bad idea, given that you think a) space is real, b) time is real, and c) there is no such thing as spacetime. Since you deny the basis of Einstein's work, while affirming the metaphysics of earlier scientific theories that cannot provide as accurate approximations to the world as experienced means that you are likely not the right person to be explaining the theory.

Indeed, that you began this thread with a popular, but likely untrue, myth about Einstein is another bad sign.

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Along obviously with no credentials within the discipline at all, and also a history of dismissing most all of 20/21st century cosmology, presumably due to a religious agenda imvho.

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Just to point out a couple of misconceptions you appear to be under.......
There was no confusion in any debate on spacetime except perhaps your own.....Secondly something does not need to be physical to be real: Space is real, time is real, spacetime is real. Thirdly any confusion on your part has more relevance with the definition of the word "real" and the philosophical application.

16. ### DywyddyrPenguinaciously duckalicious.Valued Senior Member

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This is no more spacetime than the M1 motorway is space.

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17. ### dumbest man on earthReal Eyes Realize Real LiesValued Senior Member

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Any suggestion of derailing is of course just plain silly.
I've seen a few of the anti mainstream brigade use that cop out.
This is first and foremost a science forum. And if our divine friend is proposing anything different, he should do it in the right and proper section.
And even if that had been done, anyone has the right to refute what they see as nonsense. Particularly in the case of the author of the OP, who is fond of stating many things, but never with any reputable link to support that.
Further more as has also been already noted, he does not qualify to be anyone of any authority to be explaining any aspect of GR which at other times he has totally derided and rejected/disowned/not accepted.
As long as he continues with his anti mainstream science propaganda without evidence, he will obviously be confronted with that reality and the reality of his own personal record he has created himself on this forum.

Last edited: Jan 18, 2016

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REPORTED!

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22. ### dumbest man on earthReal Eyes Realize Real LiesValued Senior Member

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Post #17 REPORTED!

23. ### Xelasnave.1947Valued Senior Member

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If you are going to attribute a statement to someone would it not be good practice to quote their actual words for not to do so runs the risk of getting things wrong. Also when quoting someone reference to the context should not be overlooked.
I have seen the quote but can not recall the exact words or context.
Explaining complex matters using anology is both difficult and dangerous.
I have followed your posts carefully in the Eddington etc discussion and say it would be refreshing to find you explain your position simply.
You seem to be preoccupied with the notion of reality when really that would seem to be an irrelevant issue.
If you are set to propose something outside mainstream perhaps do so in another section.
It is a pity you failed to read the link I posted re the observations in 1922 in Australia confirming GR.
I find graphs useful to describe reality so at this point I can not see where your arguement is leading us.