Time as a dimension, can spatial length be applied to it?

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Discussion Overview

The discussion revolves around the concept of time as a dimension and whether spatial length can be applied to it, particularly through the use of the Planck length and time. Participants explore theoretical implications, mathematical relationships, and the intersection of time and space in the context of relativity and gravity.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants propose using the formula "Planck length/c = Planck time" to convert time into a spatial distance, suggesting it could indicate how far something is through time.
  • Others express skepticism, citing limits and obstacles at the Planck scale where concepts of size and distance may break down due to quantum indeterminacy.
  • One participant presents a simpler equivalence of 1 second equating to approximately 0.3 gigameters, discussing implications for time dilation and motion through space.
  • Another participant challenges the idea that time and space can be treated as perpendicular, suggesting that they are never truly perpendicular in the real universe.
  • Some participants mention the relevance of mass in the context of speed and gravitational attraction, with one noting that the discussion assumes flat spacetime for simplicity.
  • A participant highlights practical applications in high-speed electronics, relating nanoseconds to spatial distances in vacuum and along cables.
  • There is a proposal to calculate gravitational attraction to an object in a different time using the conversion formula, but others caution that this approach becomes complicated when considering general relativity.
  • Some participants clarify that Newtonian gravity is not compatible with relativity, suggesting the need for Einstein's field equations for accurate calculations.

Areas of Agreement / Disagreement

Participants express a range of views, with some agreeing on the potential for conversion between time and spatial distance, while others raise significant doubts and highlight complications, particularly in the context of general relativity. The discussion remains unresolved with multiple competing perspectives.

Contextual Notes

Limitations include assumptions about the applicability of certain formulas at the Planck scale, the dependence on definitions of time and space, and the unresolved complexities introduced by general relativity and gravitational interactions.

mcjosep
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Could you use the formula "planck length/c=planck time" to convert time into a spatial distance? Using that to tell how far something is through time.
 
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mcjosep said:
Could you use the formula "planck length/c=planck time" to convert time into a spatial distance? Using that to tell how far something is through time.

Sure. I don't see why not.
 
The equivalence of time and distance is much simpler then that. 1 second = 0.3 gigameters (Approximately)
Using that equivalence you can say that all objects travel at the same rate, C, at least as far as special relativity is concerned, I suspect GR changes that.
If a clock is not moving through space, it is moving through time at 1 second / second, or 0.3 Gm/s. If it is moving through space at ,for example, .1 Gm/s then you can compute the time dilation as a simple right triangle problem with space as one leg, time as the perpendicular leg, and the hypotenuse as a constant. The space side in my example is .1 Gm, the Hypotenuse is 0.3 Gm, so the time side, which is perpendicular to the space side must be about .283 Gm. So for every second, or .3 Gm the stationary observer's clock measures, the traveling clock measures about .943 seconds, or .283 Gm.

I suspect GR changes and complicates this somewhat. I don't understand GR well enough to say, but I'd suspect that time and space may not always be perpendicular, moreover, the triangle I just described may have to be constructed in non-euclidean space.
 
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mrspeedybob said:
Using that equivalence you can say that all objects travel at the same rate, C,

only for massless objects, like the photon
mrspeedybob said:
time and space may not always be perpendicular,
they are never 'perpendicular'
 
alw34 said:
only for massless objects, like the photon
What's mass got to do with it?
I think you must have misunderstood what I wrote. If you can explain why you think mass is relevant I might be able to re-explain myself more clearly.

alw34 said:
they are never 'perpendicular'
In the real universe, that may be true. I'm assuming flat space-time for simplicity's sake.
 
For those of us who are into computers and high-speed electronics, 1ns corresponds to 0.3m in vacuum and about 0.2m along a cable. That is why layout becomes very critical at Gigahertz clock speeds.
 
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mcjosep said:
Could you use the formula "planck length/c=planck time" to convert time into a spatial distance? Using that to tell how far something is through time.
Yes. Or you can use any units you like. For instance you can say that a typical human is about 7E17 m long in time compared to about 2 m long in height. The conversion factor is c in whatever units you use.
 
alw34 said:
they are never 'perpendicular'
He is talking about four-vectors, ##(ct,x,y,z)##. Where ##(1,0,0,0)\cdot(0,1,0,0)=0## indicates that time is perpendicular to space, although "orthogonal" may be a better word.
 
  • #10
So could you say I am gravitationally attracted to something in a different time than right now and calculate that attraction by using this conversion formula and saying that length is the my radius to that object?
 
  • #11
mcjosep said:
So could you say I am gravitationally attracted to something in a different time than right now and calculate that attraction by using this conversion formula and saying that length is the my radius to that object?
No.

I know you want more of an answer then that, but the instant you start considering gravity in the context of relativity, things get HUGELY more complicated. GR is way beyond my math skills.
 
  • #12
mcjosep said:
So could you say I am gravitationally attracted to something in a different time than right now and calculate that attraction by using this conversion formula and saying that length is the my radius to that object?
It is not clear from your question, but I assume that you are thinking of "calculate that attraction" being Newton's law of gravitation. Unfortunately, Newtonian gravity is not compatible with relativity, so that won't work. Instead you would need to calculate gravity using the Einstein field equations.
 

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