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The last potion of the my statement should have read:
2. That time is the change in a blank of an object relative to an observer as measured using an arbitrary coordinate system based on the observer’s blank. The arbitrary coordinate system for example could be any periodic, uniform event device using any convenient units. Can someone fill in the blanks for the definition of time (with “clock” being the periodic, uniform event device and therefore cannot be used in the blanks) or is there a better definition for distance and time that creates the equivalence that Dr. Greene assumes?
The original had “< b l a n k >” which was edited out when I submitted the reply.
In “15.2 Time Dilation: Intuitive Explanation”, Dr. Greene states two definitions:
1. The speed of an object through space is “how much distance the object covers in a given amount of time that elapses on our laboratory clock; the clock that we have right here”.
2. The speed of an object through time is “the amount of time that has elapsed on that object compared to the amount of time that has elapsed on our clock here in the laboratory”.
He then instructs the us to:
“Just replace what we previously called space with what we’re now thinking about as time.”
to make the statements equivalent.I don’t follow that by just simply using substitution that the two definitions are interchangeable. The original question still remains valid. To try to get to a point of equivalency, two concepts must be defined first.
1. That distance is the change in a location of an object relative to an observer as measured using an arbitrary coordinate system based on the observer’s location. The arbitrary coordinate system for example could be Cartesian or Polar using any convenient units.
2. That time is the change in a of an object relative to an observer as measured using an arbitrary coordinate system based on the observer’s . The arbitrary coordinate system for example could be any periodic, uniform event device using any convenient units.Can someone fill in the for the definition of time (with “clock” being the periodic, uniform event device and therefore cannot be used in the ) or is there a better definition for distance and time that creates the equivalence that Dr. Greene assumes?
What is the definition of present, past, and future? If present is defined as the instance a photon is emitted from observer A, then regardless of how far away an observer B is or observer B’s velocity relative to observer A, observer B will always see observer A’s past since the photon must travel from A to B regardless of time dilation. For either observer to see the other’s future would require the photon to reach say observer B before it was emitted by observer A. In the train examples, there was never a situation from either the onboard observers or the station platform observers where any one signed before the light turned on. Whether president forward signed first or both presidents signed together, the events were always in the past to any observer.
The Cosmic Background Radiation (CBR) is presented in many of the presentations as an expanding shell surrounding the known universe as if it were a shock wave from the Big-Bang. If this were so, then it would imply an “edge” to the universe and therefore a “center” could then be defined. CBR actually permeates all of the observable universe as residual energy left over from the Big-Bang. Since there is no definable “edge” to the universe, there can’t be a definitive “center”.
Robert, I think your thoughts are well taken. Prof. Guth doesn’t like to assume that the big bang was uniform but assumes that inflation was. According to Prof. Guth’s version of inflation theory, the negative gravitational field starts the period of uniform inflation. As the inflation progresses, the matter/energy making up this field randomly decays which in his words “stops the inflation” and the universe “coasts” to its present structure. The random decay must have taken place over a time period which should mean that the inflation did not stop at one time in all locations. Could this non-uniform inflation period have produced the seeds for the “clumpy matter” universe we see now? I would think that this non-uniformity as the inflation slows would be a bigger factor that the quantum uncertainty would introduce.
Since the information contained within a black hole would be due to the accretion of matter, it seem to me in that the area of the event horizon would be a good approximation to its information capacity. But this accretion is not uniform from location to location all over the event horizon. Is there then local areas of concentrate information which then spreads over the surface? Is the surface of a black hole always “smooth” or can there be at least temporary irregularities? Given a black hole which has spin and therefore would have an event horizon that would be ellipsoid in shape, as material falls into the event horizon and the radius changes, would the event horizon oscillate? Would this oscillation cause gravitational waves proportional to amount of matter being accumulated, the spin, and the frequency of the oscillation?
If the Higgs field imparts or transfers to a particle moving through it a given amount of mass which should be equivalent to E / c^2, does that infer that there is a corresponding depletion in the Higgs field by that amount of energy? Is there a reverse transfer of energy to the Higgs field by a particle which “gives up” its mass characteristic?