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

AI Thread Summary
The discussion explores the possibility of converting time into spatial distance using the formula "Planck length/c = Planck time." Participants debate the implications of this conversion, noting that at the Planck scale, traditional concepts of size and distance become problematic due to quantum indeterminacy. The conversation touches on time dilation and the relationship between time and space, suggesting that they may not always be perpendicular, especially in the context of general relativity (GR). It is emphasized that gravity complicates these calculations significantly, as Newtonian gravity does not align with the principles of relativity. Ultimately, while the conversion is theoretically possible, applying it in the context of gravitational attraction requires more advanced understanding of GR.
mcjosep
Messages
35
Reaction score
0
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.
 
Physics news on Phys.org
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.
 
Last edited:
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.
 
Last edited:
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.
 
Back
Top