Is Time the Fourth Dimension?

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Discussion Overview

The discussion centers around the concept of time as the fourth dimension and its relationship with spatial dimensions. Participants explore various definitions and interpretations of time, including its mathematical representation and its implications in physics, particularly in relation to entropy and the nature of the universe.

Discussion Character

  • Exploratory
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants propose that time is the fourth dimension and is correlated with the radius of a sphere, suggesting that the compression or expansion of space affects time.
  • Others argue that spatial dimensions are dependent on time, asserting that knowing a time coordinate allows for the determination of spatial coordinates, but not vice versa.
  • One participant claims that time can be defined as the increase in entropy, while another challenges this by stating that time is the direction in which entropy increases, not the increase itself.
  • There is a suggestion that if time travel were possible, time might be regarded as a spatial dimension, although this is presented as a speculative thought.
  • Some participants question the mathematical representation of time and space, with one noting that a radius defined in terms of spatial coordinates does not equate to time.
  • Another participant emphasizes that distance and time are fundamentally different quantities, arguing against the idea of measuring distance in units of time.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the nature of time and its relationship with space, with no consensus reached on the definitions or implications discussed.

Contextual Notes

There are unresolved mathematical interpretations and assumptions regarding the definitions of time and space, particularly in how they relate to physical phenomena like entropy and the structure of the universe.

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http://www.aphysics.netfirms.com
Time Definition
If we go to search everything about definition of time finally will be a disillusion because of confusing definitions.
My theory will brink you clear vision about fog and confusion.

Here the definition of time: Time is 4th dimension and is equal to radius of sphere where the space is defined. Compression or expansion of space will generate compression or expansion of time. All four dimensions are correlated and cannot be separated. More concise: space is surrounded by time or defined by time and part of time. This is way so far time cannot be seen because is hard to be seen from inside.
Simple Math of Time Definition

At any moment a partition of time d(t) is a partition of radius d(r) d(t)=d(r) and include space d(s)
The vector r(t) is: x = x (t)
y = y (t)
z = z (t)
Any movement in space (x, y, z) will be: r = (x, y, z,)= xi + yj + zk
If r(t) derive twice R
First derivate r’(t) = v (speed).
Second derivate r”(t) = a ( acceleration)
Speed vector v(t) = r’(t)=( x’(t), y’(t), z’(t) ) = x’(t)I + y’(t)j + z’(t)k)
Acceleration vector:
a(t) = v’(t) = r”(t) = ( x”(t), y”(t), z”(t)) = x”(t)I + y”(t)j + z”(t)k
Here how space is surrounded by time.
 
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Originally posted by toppam
Compression or expansion of space will generate compression or expansion of time.

I have a problem with this. I have always felt that spatial dimensions are dependent on time. For example, suppose I were to document my whereabouts using coordinates such as (t,x,y,z), where t is time and x,y,z are space. Right now, I could be (April 25 5pm, 40*N, 80*W, 20ft above sea level). These are crude examples, but bear with me.

If only the time coordinate existed, I could know the other three because at that time I can only be in one place. For the time coordinate of April 25 5pm, I can only be in that aforementioned spot. However, given the three spatial dimensions (40*N, 80*W, 20ft above sea level), this is not enough information to derive the time coordinate, because I could be at this exact spot tomorrow (disregarding Earth's rotation, etc)!

Thus, I feel it is only proper to say that "The compression or expanion of time will generate compression or expansion of space." Overall, a small point, but I feel it is a valid one.
 
Quite simply, time is the increase in entropy, and can be used as a coordinate.
 
Originally posted by MajinVegeta
Quite simply, time is the increase in entropy, and can be used as a coordinate.

Time is not the increase in entropy. It is the direction in which entropy increases, yes, but the increase of entropy is just an event, not a dimension.
 
Locutus, if time travel were feasible, then time would no longer be regaurded as a coordinate but as a spatial dimension instead. (Not that time travel will ever be feasible)
Just a thought.
 
Originally posted by toppam


Here the definition of time: Time is 4th dimension and is equal to radius of sphere where the space is defined.

r=sqrt(x2+y2+z2)? But this is space again (r is length), not time.
 


Originally posted by Alexander
r=sqrt(x2+y2+z2)? But this is space again (r is length), not time.
What about r = 10 billion light YEAR?
 
What do you mean?
 
Originally posted by Alexander
What do you mean?
I mean a distance can be measured directly at unit of time .
This r is radius of sphere, universe in this case. Though on my glance this is the time only. Time which had passed from a moment when "inverse BB" began.
 
  • #10
You can't measure distance in units of time. Distance and time are different quantities - they have different properties.

To express distance in units of time, you may multiply time by proper dimensional factor (say, speed of sound) and then you may say that the size of universe is about one quadrillion sound-years. So what?
 
  • #11
Originally posted by Alexander
You can't measure distance in units of time. Distance and time are different quantities - they have different properties.

To express distance in units of time, you may multiply time by proper dimensional factor (say, speed of sound) and then you may say that the size of universe is about one quadrillion sound-years. So what?
The Light upon its "travel" creates the illusion of space.
 

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