Originally posted by Jimmy
Hello. I'm new here and found this thread interesting. I'll state up front that I have no formal education in physics above an associates degree in electronic egineering technology. Anything I say may be taken with a grain of salt. I should say, rather, I won't be offended if someone tells me to get lost. :)
I've often thought about time as it relates to physics (SR) and how we perceive the 'flow' of time or alternately, our motion through time. Don't worry, this isn't the beginning of some cranky theory.
Consider the three spatial dimensions. 3D-Space has three axes which are mutually perpindicular. These three axes define the degrees of freedom of motion which we can experience in that space. We can move forward, backward, left, right, up and down. We can also rotate around each of these axes in two different directions.
There are two other degrees of freedom that I have not mentioned: Faster and slower. On the surface, they seem to be completely unlike the other motions I've listed above.
Consider Space-time. When an object is plotted on a space-time diagram, acceleration (a change in speed) appears to be a change in direction or a rotation around a fourth axes. I realize that this isn't evidence that time is a physical dimension but wouldn't a fourth physical dimension be necessary to accommodate the extra degree of freedom that acceleration entails? This is not a rhetorical question and I am interested in everyone's thoughts on this.
If we consider the three spatial dimensions as physical and time as just an abstraction, does that leave any room physically for acceleration? It seems to me, and I freely admit that I could be wrong, that a fourth 'physical' dimension is needed to go faster and slower. The physical sensation of a change in speed is curiously similar as that of a spatial rotation. Again, I realize that this isn't proof but it is compelling for me.
Of course, there are definite asymmetries bewteen spatial rotations and acceleration (change in speed). An object can rotate indefinately in space but we certainly can't 'rotate' indefinitely around this fourth axis. There is a definite limit on how fast we can go or how much we can rotate around this fourth axis. Can acceleration in this sense be considered a hyperbolic rotation? I'm not sure of the details but wouldn't you have to use the hyperbolic functions to describe acceleration in a 4D context?
When considering time to be a physical property of the universe, as in SR and GR, the physical implications such as time dilation, length contraction, etc, seem to be confirmed to a high degree of accuracy eperimentally.
Like I said above, I'm not a physicist and I am curious as to whether my thinking is correct if even partially.
The problem seems to relate to the SPACE itself that is dynamic, ie:Contracting Frames and Expanding Frames.
If one was to know that the spacetime you occupy is in Expansion, then say you move to another part within this spacetime, then it is obvious that the space you trancend is scale dependant. From one location to another the space that surrounds you will be moving away from you in all directions (expansion) what you experience is the dilation of movement 'in-between', from loaction to location.
Now if one was to move from a 'contracting' frame to an Expanding frame, then you would have to move from Galaxy to Galaxy, with the intervening space being the 'Expanding frame', upon arrival you would have to agree that the Galaxy that arrive at would appear to be in Contraction.
It seems counter-intuitive that we exist inside spacetime (Galaxy) that is steady, the space we have all around us is expanding by a different process that of the intervening space between Galaxies, namely Galaxies have Stars that produce Photon Pressure, this gives Spacetime its own steady-state of Spacetime.
Quote:It seems to me, and I freely admit that I could be wrong, that a fourth 'physical' dimension is needed to go faster and slower. The physical sensation of a change in speed is curiously similar as that of a spatial rotation. Again, I realize that this isn't proof but it is compelling for me.
But this cannot have another dimension hidden within?..this is what Galaxies are, they are fused space(the intervening expanding space) with another space (photon-space around matter) into a dimensional area we call Spacetime. Any motion within Galaxies is along 3-dimensional routes that are equivilent, not until you leave a Galaxy would you be able to determine the space you are moving in(intervening space) has no Time componant, and is completely 2-dimensional, and all routes are now restricted to just motions along these dimensional routes, fixed and have constant restrictions such non-rotational motions.
The straightest path through spacetime(Galaxies-the more matter the more curved space) is along the curves caused by Matter.
The straightest path through space is always fixed as there is no Matter, no 'Time-curves', and is therefore instant and direct.