Spacetime, the Universe, the Present and the Future

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Discussion Overview

The discussion revolves around the nature of spacetime, the concept of the present, and the implications of time being treated as a dimension similar to space. Participants explore whether this perspective leads to a static universe and a predetermined future, as well as the philosophical implications of these ideas in the context of modern physics.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification
  • Philosophical

Main Points Raised

  • Some participants suggest that if time is akin to a spatial dimension, it implies a static universe where the present is merely a construct of consciousness, potentially leading to a predetermined future.
  • Others argue that time and space are not completely equivalent, noting that one cannot "turn around" in time as one can in space, referencing the nature of world lines in Minkowski spacetime.
  • There is mention of a lack of consensus regarding whether the future is predetermined, with references to various papers that present differing views on the topic.
  • One participant raises concerns about reconciling an objective 'present' with relativity, suggesting that while simultaneity poses challenges, a subjective experience of the present may still exist within individual frames of reference.
  • Philosophical perspectives, such as those from Kant and Julian Barbour, are introduced, with Barbour's view that time is an illusion being highlighted as a point of interest.

Areas of Agreement / Disagreement

Participants express multiple competing views on the nature of time and spacetime, with no clear consensus on whether the future is predetermined or how the present is conceptualized within the framework of relativity.

Contextual Notes

Discussions include references to philosophical interpretations of time and consciousness, as well as the mathematical treatment of time in physics, which may not align with physical experiences or perceptions.

Who May Find This Useful

This discussion may be of interest to those exploring the philosophical implications of time in physics, as well as individuals curious about the relationship between spacetime and consciousness.

Seeker2K
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At http://en.wikipedia.org/wiki/Spacetime#Historical_origin I read the following quote:
In 1895, H.G. Wells in his novel, The Time Machine, wrote, “There is no difference between Time and any of the three dimensions of Space except that our consciousness moves along it.” He added, “Scientific people…know very well that Time is only a kind of Space.”

Wouldn't this imply that the universe (respectively spacetime) is actually static and that the present doesn't really exist except for our consciousness? And wouldn't this also imply that in such a universe the future would also be already determined, if time is only another dimension like space in the static construct of spacetime?

What is the general understanding regarding these issues in the field of physics today? Or is this more or less a matter of debate and/or personal interpretation of spacetime?
 
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Seeker2K said:
At http://en.wikipedia.org/wiki/Spacetime#Historical_origin I read the following quote:


Wouldn't this imply that the universe (respectively spacetime) is actually static and that the present doesn't really exist except for our consciousness? And wouldn't this also imply that in such a universe the future would also be already determined, if time is only another dimension like space in the static construct of spacetime?

What is the general understanding regarding these issues in the field of physics today? Or is this more or less a matter of debate and/or personal interpretation of spacetime?
Since time plays the same role mathematically, but not physically, then there is a sense where one can say that space plays the same role as time but the fact still remains that this relationship is a role mathematically, but not physically. Either way the universe exist. If it didn't then I'd be hard pressed to say who posted this thread. :smile:

Pete
 
Seeker2K said:
At http://en.wikipedia.org/wiki/Spacetime#Historical_origin I read the following quote:


Wouldn't this imply that the universe (respectively spacetime) is actually static and that the present doesn't really exist except for our consciousness? And wouldn't this also imply that in such a universe the future would also be already determined, if time is only another dimension like space in the static construct of spacetime?

What is the general understanding regarding these issues in the field of physics today? Or is this more or less a matter of debate and/or personal interpretation of spacetime?


I would say that there is NOT a consensus whether the future is predetermined or not.

There are apparently some enthusiasts at the Wikipedia who have written and believe that there aren't any alternatives.

For some papers that take different views see the references in my post in PF

https://www.physicsforums.com/showpost.php?p=1176689&postcount=6

you may also find the thread of which this is a part of some interest (select view thread).
 
Time and space are not completely equivalent

H. G. Wells didn't have it quite right, if you are trying to read that (anachronistically) as a description of Minkowski spacetime. You can turn around in space---your world line can describe a helical arc--- but you can't turn around in time--- your world line can't "turn over" and start heading into the past.
 
Chris Hillman said:
H. G. Wells didn't have it quite right, if you are trying to read that (anachronistically) as a description of Minkowski spacetime. You can turn around in space---your world line can describe a helical arc--- but you can't turn around in time--- your world line can't "turn over" and start heading into the past.

besides that (the "arrow of time" vs. some "arrow of space" which i don't think exists outside of the event horizon of black holes), i don't think (from an amateurish read) that they have precisely the same role mathematically (responding to Pete). [itex]t^2[/itex] has a minus sign attached to it where [itex]x^2, y^2, z^2[/itex] all have plus signs.
 
pervect said:
I would say that there is NOT a consensus whether the future is predetermined or not.

Seems you are right...

For some papers that take different views see the references in my post in PF

https://www.physicsforums.com/showpost.php?p=1176689&postcount=6

you may also find the thread of which this is a part of some interest (select view thread).

Yes, I took a look at the thread and at the papers. Dieks' "Time in special relativity and its philosophical significance" sounds interesting, but unfortunately I can only access the abstract.
The paper by Mauro Dorato is interesting as well, but apparently he is supporting a kind of kantian point of view in which time is something purely mental and only exists in our consciousness. I wonder how objects are supposed to exist then, if time and space only exist in our minds - does spacetime only exist in our minds/consciousness as well then? I have to say that I am no expert regarding Kant though. :wink:
However, according to the author of that paper Kant’s view of time is actually vindicated by relativity.

Personally I have thought about all of these issues and currently think that it could be problematic to combine an objective, universal 'present' with the theory of relativity, as there would be problems with simultaneity. However I think that it should still be possible that there is something like a 'present' with an open future for every existing frame of reference in space. The existence of such a shifting 'present' doesn't directly follow from the concept of spacetime as all points in the time dimension appear to be equal there, but something has to be added to this concept anyway, as there surely is something as an 'experienced present' that moves through time from the past to the future in our consciousness. Everybody can surely say that there is a certain moment in time that he/she is experiencing right now (for him/her at least). The question remains if it only exists in our minds or if there is some general kind of 'flow of time' with a past, present and open future.
 
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Some might be interested in reading Julian Barbour's views on time. He wrote a book called "The End of Time".

His website is called http://www.platonia.com/index.html" .

" ... time is an illusion.
The phenomena from which
we deduce its existence are real,
but we interpret them wrongly.
My arguments are presented in
The End of Time."

- Julian Barbour.
 
Last edited by a moderator:

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