PeterDonis said:
What does "occur" mean? How do I test, experimentally, whether an event has "occurred"? The obvious answer is to observe it, but if I observe an event, it must be in my past light cone.
You still ldon't know what my point is.
You told me that an observer doesn't know whether the event he observes did exist before it is observed; your post #56-quote-<<More precisely, you have no way of testing by experiment whether or not the event "existed" before you observed it--because any experiment would involve observation.>>
Hence putting the observed event in your past lightcone is wishfull thinking,
because you don't know the event happed before the event of observation.
If one talks of mathematical model, be it SR, then I would like to know what it is based on. The simple fact of making a model with an event "in the past light cone of that model" is based on the premise that the event occurred before the apex event of the light cone. But you doubt -see quote above- whether the event occurred before it is observed. This makes me say that the light cone, the SR model uses the premise "events
do occur before observation".
Yes, one should question what 'occur' means. We are certain that the observer's present event does occur. That's a good start. But do you know anything "occurred in the past"? No. Then what is the meaning of 'occurred'?
Besed on the premise that "we don't know whether an event occurred in the past or not" I consider it a fair question asking what the past light cone model is based on. I will agree that the model is based on "observations", but because the premise tells us we don't know whether an event occured/occur(?) before observation, then what do we mean by "observation". Read on.
Meaningless question. Any event in your past light cone is fixed and certain. What events are in your past light cone depends on what event on your worldline you are treating as your "present" event.
I want to know what you mean by that. When you make such a statement you already have your model in hand/in mind. I want to know what the meaning is of an event being in the light cone, as far as observation is concerned. Putting an event in a past light cone of the SR model
does automatically mean the event occurred before observation (whether it is later observed or not is irrelevant). Would you agree with that or not?
If the event is only put in the past light cone when 'observing/seeing' the event, then it means we are not allowed to draw any event in the past light cone. Because past light cone means "event occurred in the past", hence event occurred before observation.
There is no "labeling" involved. You are treating "fixed and certain" as something that has to happen to an event, physically. It's not. It's just a property in the model.
I want to know what events you draw in the past light cone. Events you observed, or also those you didn't observe?
When and why may an event be located in the past light cone? How does it get there, and when?
Is it because the event was
not in the light cone, and then as time goes by, the past light cone gets bigger, and the event that was outside then gets into the past light cone? If not, then when does the event gets located in the past light cone?
We don't know whether an event was outside the lightcone before it entered the light cone, isn't it?
If there
did occurr an event
before it entered the lightcone, then it would be correct stating the event gets labeled 'fixed and certain' when it enters the light cone. And in that case the event gets labeled before the observer observes the event yet. but you don't agree with my labeling scenario. Hence I still don't understand your "fixed and certain".
I haven't said anything about "know".
I'll rephrase it. When I said <<the above doesn't mean that you know that the event occurred before you observed it.>> I mean that you use the premise that you don't know whether an event occurred before observation.
Once again: you have a model, and the model treats events in the past light cone of some chosen event, the one you are calling the "present" event on your worldline, as fixed and certain.
That doesn't answer my question. My point is that you cannot make/construct a past light cone model if it doesn't use a premise "events occur before observation".
You keep on repeating we don't know whether an event occurred before observation or not, -and I agree, in principle-, I then wonder what the past light cone of the SR model is based on if the option "events do
not occur before observation" is used.
Strictly speaking, they are events you could have observed, at some event on your worldline prior to the event you are calling your "present" event, just looking at the causal structure of spacetime. Whether you actually observed them depends on things that are irrelevant to this discussion, like whether you were paying attention.
They are not irrelevant to the discussion. They are at the core of the discussion to know whether relativity of simultaneity requires Block Universe or not. But you don't seem to understand why. I don't question causality of the past light cone. That's not what is being discussed (actually I should, because if one doesn't know whether events occurred before observation, then what is the meaning of causality (f.ex event occurs, light travellingfrom event, then hitting my eye... but I won't push it that far yet)
I concentrate on the meaning of your post #56-quote-<<More precisely, you have no way of testing by experiment whether or not the event "existed" before you observed it--because any experiment would involve observation.>> and what it means for constructing a light cone model, and then using the model.
Nope. You still don't understand what a model is. A model is a tool for making predictions. You don't have to predict what happened in your past light cone, at some chosen event you are calling your "present" event, because those events are fixed and certain in the model. You only have to predict events outside your past light cone. That's what the model is for.
I know, that's why I want to concentrate on the meaning of putting events in the past light cone. I don't know how you interpret your own words, but for me your post #56-quote-<<More precisely, you have no way of testing by experiment whether or not the event "existed" before you observed it--because any experiment would involve observation.>> means one doesn't know whether there are events in such a thing as past lightcone model. I think the whole SR model based is construced on loose sand if one uses the option "events don't occur in the past before observation". But the SR mode does make sens if one uses the premise "events
do occur in the past before observation".
Any event in the model that is not in the past light cone of whatever event you are calling your "present" event is not fixed and certain in the model; it's predicted, and the prediction is not 100% guaranteed to be correct. That is true. Any model will have the same property--there will be some things that are fixed and certain, and some things that are predicted and might be wrong.
It still doesn answer the question about the past lightcone and "fixed and certain" events.
You cannot put an event in the past light cone if you don't use the premise "events do occur before observation". If you would consider the option "events do not exist before observation", then there cannot even be such a thing as 'past light cone'. Don't you understand that?
I haven't said anything about "know". See above. You need to get rid of your preconceptions and stop reading things into my posts that I didn't put there.
When I said <<They are fixed and certain, but you don't know whether those events actually occurred before observation that event of observation.>>, I meant "one doesn't know". I thought it was obvious, but obviously one has to be very careful what's obvious or not. Mea culpa.
Yes, I still I wonder what you mean by fixed and certain. Can event can be fixed and certain, irrelevant of whether the event is observed or not? In that case you mean by fixed and certain: all events in the past light cone. then my question is: when are you allowed to put an event in the past light cone model?
I feel sorry that you have the impression that I am reading things into your posts that you didn't put there. I only try to find out what you put in there. Hence I try to formulate what I think you put in there. You shouldn't be upset that I might read things you didn't put in there. It's part of the game of discussions, and getting at the bottom of things? Or not?
We are talking about SR here, not about theories of consciousness. You are making this way too difficult.
I'm not talking about theories of consciousness. Every time the word 'consciousness' popps up in science topics somebody starts panicking. Look, I try to understand what observations are if one considers the option events
do not occur before it's observed, based on your post #56-quote-<<More precisely, you have no way of testing by experiment whether
or not the event "existed" before you observed it--because any experiment would involve observation.>> Please explain what observations are if one considers the option events
do not occur before it's observed.
Again, we are talking about SR here,
The talking involves the second premise of your BU article.
not about theories of consciousness or metaphysical questions about how we can observe or know anything at all. You are making this way too difficult.
My impression is that you might be making it too easy in your BU article.
I'm not interesed about theories of consciousness or metaphysical questions. I want to know what the implications of your statement -whether or not the event "existed" before it's observed- are for constructing the SR model, and then using that model. You know why. In your BU article a second premise is introduced, to be able to refute Block Universe. I try to understand that second premise. What the
exact meaning is of that premise. And to do that I have to understand the meaning of your "fixed and certain". I still don't understand what it means. Because it involves the problem whether events occurred before observation or not. Hence I want to know what "occurred before observation" means for the past light cone. If you insist that there is an option that events not occur before observation, the
how can there be events in a past light cone if one considers the option events do not occur before observation?
Because you keep on wandering off into the weeds of theories of consciousness and metaphysics,
Don't put things into my words that I didn't put in there.
Because you seem getting very nervous about reading the word 'consciousness'. I'll keep it safe and rephrase it:
If one considers the option events
didn't occur before observation,
then what do you mean by 'observation'? Please answer that question. Observation involves something/event that is observed and did occur before observation.
If not, then please tell me what observation means for using that SR model. Is that -your quote- "making it too difficult"?
My point is that 'observation' doesn't mean anything if one
doesn't use the premise "events do occur before observation". But for that option I tried to rescue the word by introducing it may be just all happening in the mind...because I guess we still want to go on using models and observations. But I shouldn't have done that. I had better stated: If one doesn't use the premise "events do occur before observations" then 'observation' cannot mean anything. Would you prefer this? '
Observation' of an event implies the event
occurred (as an observer independent unit) before observation. Can I get agreement on that?
instead of just looking at the simple model I am describing.
If I 'just look at the model', then it requires Block Universe. But your article tells me that's a too easy way of putting things. In your article refuting block universe you didn't 'just look' at the model. A second premise is introduced, and I want to know what you mean 'exactly' what that second premise means. It leads to some "fixed and certain" qualification of events, questions about whether events do exist before observation or not, what it means for the past light cone, and what observation means. If you consider this making it too difficult, feel free, but I like to get to dig things a bit further. May I?
In the model, there is some event that you call your "present" event. Events in the past light cone of that event, in the model, are treated as fixed and certain. Events not in the past light cone of that event, in the model, are not treated as fixed and certain. That's it. That's all there is to it.
I want to know what the meaning of a model with past light cone is if you don't know whether events exist or not before observation, hence considering the option events do not occur before observation.
If I would state that the SR model (let's concetrate on the past lightcone) is based on the premise events do exist before observation, I guess you don't agree?
Your approach, taken to its logical conclusion, would say that we cannot do physics at all unless we first understand how consciousness works. That's absurd.
I won't push it that far. We can base models for making predictions. I want to know the premise(s) the model is based on. At its core it's based on observing the past. Agreed? "Observation" means: observing something that was there
before observation. But if one considers there is an option that events didn't occur before observation, then what is the meaning of observation? Please answer that question. I tried to answer that question, but I had to use the word "consciousness", which makes you think I want to get involved in -your quote-<< theories of consciousness or metaphysical questions>>. I don't. But if one considers there is an option that events didn't occur before observation, then please tell me what the meaning of observation is?
Just trying to understand what you post. Nothing else.
People have been doing physics for centuries without knowing how consciousness works, except for the basic rough and ready pragmatic knowledge that everybody has just by being conscious and going through their daily lives. That is enough for what we're discussing here.
No, it isn't. For the discussion here it's important to know what you mean by fixed and certain, and what the implications of your post #56-quote-<<More precisely, you have no way of testing by experiment whether or not the event "existed".>> are for the light cone model. We can then deal with your BU article
If it isn't enough for you, then I'm afraid nothing anyone could possibly say in this discussion is going to satisfy you. Sorry.
You know, that might indeed be the case. But I do understand other participant's posts, probably because they have the same premise in mind as I do.
The other point of your article I don't understand: in that article you refute solipsism, but your post #56-quote-<<More precisely, you have no way of testing by experiment whether or not the event "existed" before you observed it--because any experiment would involve observation.>> leaves the option 'solipsims' still open, because in case the events do not occur before they are observed, there is nothing left but your present now event.
I don't know about other readers of your BU article (although 8 pages of discussion in that other thread discussing your article gives me a hint) , but I need a lot more information for trying to understand the full content of your article.
Thanks for reading this long post.