Please, no more of this stupid "t=0 duration" crap, that's not what the light cone says.
We can hope, but I fear our hopes will come to naught.
Last edited:
Please, no more of this stupid "t=0 duration" crap, that's not what the light cone says.
We can hope but I fear out hopes will come to naught.
Sorry to disagree, but I feel you seriously underestimate the significance of the light cone diagram as it relates to Minkowski/Einstein space time...and physics in general.No, no, and no. There's no need to invoke even more complicated ideas to resolve a simple misunderstanding. If you can't even understand light cones, it's ridiculous to go further still and try relating them to quantum entanglement or de Sitter spaces. Your questions about time could be asked of classical Newtonian physics just as easily, and you could raise the exact same illogical objections. The oberver exists over a finite nonzero duration of time, and the light cone represents the points where events occuring at various times can affect them or be affected by them, given that no information can be carried from one event to another faster than light. Please, no more of this stupid "t=0 duration" crap, that's not what the light cone says.
A light cone is the path that a flash of light, emanating from a single event (localized to a single point in space and a single moment in time) and traveling in all directions, would take through spacetime. If we imagine the light confined to a two-dimensional plane, the light from the flash spreads out in a circle after the event E occurs, and if we graph the growing circle with the vertical axis of the graph representing time, the result is a cone, known as the future light cone. The past light cone behaves like the future light cone in reverse, a circle which contracts in radius at the speed of light until it converges to a point at the exact position and time of the event E. In reality, there are three space dimensions, so the light would actually form an expanding or contracting sphere in 3D space rather than a circle in 2D, and the light cone would actually be a four-dimensional version of a cone whose cross-sections form 3D spheres (analogous to a normal three-dimensional cone whose cross-sections form 2D circles), but the concept is easier to visualize with the number of spatial dimensions reduced from three to two.
Because signals and other causal influences cannot travel faster than light (see special relativity and quantum entanglement), the light cone plays an essential role in defining the concept of causality: for a given event E, the set of events that lie on or inside the past light cone of E would also be the set of all events that could send a signal that would have time to reach E and influence it in some way. For example, at a time ten years before E, if we consider the set of all events in the past light cone of E which occur at that time, the result would be a sphere (2D: disk) with a radius of ten light-years centered on the future position E will occur. So, any point on or inside the sphere could send a signal moving at the speed of light or slower that would have time to influence the event E, while points outside the sphere at that moment would not be able to have any causal influence on E. Likewise, the set of events that lie on or inside the future light cone of E would also be the set of events that could receive a signal sent out from the position and time of E, so the future light cone contains all the events that could potentially be causally influenced by E. Events which lie neither in the past or future light cone of E cannot influence or be influenced by E in relativity.
re: http://en.wikipedia.org/wiki/Light_cone
good question!!But the forum says he only last posted at 7:00pm, how can he exist now?
But the forum says he only last posted at 7:00pm, how can he exist now?
Certainly some of the "pseudo wanna-be experts" on this board perhaps, but certainly NOT the real experts that constructed the theories, such as Einstein, Minkowski, De Sitter, Lorentz etc...and later Feynman and others...Sweet freaking Jesus, your right! It really is rather funny (in a sad sorta way) that QQ is all smug thinking he has found some sort of paradox to confound the experts.
That little pop you heard was you blowing QQ's mind.
and I suppose you believe your opinion matters! Why ?But you aren't going on the journey, you're doing physics by random-quote + fantasy.
Don't tell me! ...you are a clandestine member of CRI?Gawd. that just blew my own mind!
But you aren't going on the journey, you're doing physics by random-quote + fantasy.
Don't tell me! ...you are a clandestine member of CRI?
too bloody right... this thread is full of it... [chuckle]And the Dunning and Kruger experiment continues.....
The remaining region of the spacetime is outside both past and future light cones. It is a new sort of region that does not appear in pre-relativistic spacetimes. It is an "elsewhere" region.
It collects all events that cannot be connected to event O by timelike or lightlike curves. Its events can only be connected to O by spacelike curves. That is, its events are "spacelike separated" from O.
If we assume that no causal processes propagate faster than light, these events are causally disconnected from O. If we are at O we cannot causally affect or be causally affected by an occurrence at an event in this "elsewhere" region. Correspondingly, we cannot exchange signals between the event at O and any spacelike separated event in this region.
There is no corresponding region in a pre-relativistic spacetime. In Newtonian theory, it is assumed that there are propagations that are arbitrarily fast and even instantaneous. An example of an instantaneus propagation is changes in the Newtonian gravitational field. If the sun were to disappear, we would know instantly on earth, according to Newtonian theory, for the sun would no longer exert a gravitational pull on us.
Sorry to disagree, but I feel you seriously underestimate the significance of the light cone diagram as it relates to Minkowski/Einstein space time...and physics in general.
I believe that the cone diagram is central the understanding of GR, SRT, and the universe in general. It is far more than what you suggest it to be.
To me, the main point of the light cones is to differentiate between past and future light events and in doing so declare that absolute rest is impossible due to the HSP having no time duration. It is also declaring in essence that the universes reality is based on an event horizon of continuous movement. [thanks for the reminder Brudep ]
the emission of a ray of light being the base line for all events universally...
It is worth some serious study... beyond what you have implied IMO.
Support your complaint with a quote please.. and if not apologize for false representation...Please stop spouting this mindless crap about observers only existing for infinitesimal durations, because that's not what physics says and that's not what light cones imply.
Support your complaint with a quote please.. and if not apologize for false representation...
[rpenner and others had thoroughly and very reasonably refuted that consideration in another thread and it has no bearing on this thread except to state that infinitesimals are irrelevant.]
If the time duration between past and future, light cones, is zero then what mathematics can be used to describe the reality of the universe [ or any relevant observer frame of reference ] at that point in time?
too bloody right... this thread is full of it... [chuckle]
Here's a quote for you:
That's from your opening post. Obviously you wouldn't be crazy enough to believe observers don't exist, but your claim and subsequent statements imply that you think this is an inevitable conclusion derived from Relativity unless we all agree to replace it with some stupid metaphysical layman model. And if your conclusion is indeed that Relativity and light cones somehow imply that observers don't exist, then you simply don't understand what light cones actually represent.Originally Posted by Quantum Quack View Post
If the time duration between past and future, light cones, is zero then what mathematics can be used to describe the reality of the universe [ or any relevant observer frame of reference ] at that point in time?