29 Aug 13
Originally posted by lemon lime
Do you agree or disagree with Einstein? It seems you were saying something else earlier. Do you think time travel into the past is or can be literally possible, or do you believe it can't happen?
Do you agree or disagree with Einstein?
No, he didn't implied that he disagrees with Einstein but rather merely pointed out my error in what I implied Einstein said.
29 Aug 13
Originally posted by lemon limeIn Twentieth Century Physics the observer takes a central role. In Newton's universe you have an absolute space and a separate absolute time, physical influences can travel instantaneously. In this universe it is possible to order events in a universal way; the state of an observer is not expected to alter what they see, specifically all observers will agree on what order events happen in. This means that there need be only one observer, this observer is assumed to be omni-cogent. In the theory observers aren't referred to, there is no need since all quantities are universal.
There is no such observer.
The observer is imaginary, so I assume you mean we can't use the idea of an observer the way I used it.
There is no way of observing the entire universe all at once and there is certainly no way of making instantaneous observations.
Hence the observer is imaginary, and can only be used as a visual aid. I sense a disagreement coming, but so far we are both on the same page.
The advent of relativity changed this. What the observer sees depends on their state of motion, with the observables in different reference frames related by Lorentz transforms. An absolute observer of the kind you described breaks the framework of special relativity, as there is a preferred frame of reference defined by the universal observer. Lorentz invariance guarantees PCT symmetry (parity, charge conjugation, time reversal), which has been tested to about 18 significant figures.
In quantum theory the situation is worse, there is an assumption in Newtonian Mechanics and in Relativity that it is possible to make observations without disturbing the observed system. In classical systems this is to all intents and purposes true - we are not going to alter the orbit of Mars by tracking it with a telescope. With quantum scale systems the act of observation drastically alters the state of the observed system. The observer becomes part of the experiment, so the kind of over-arching objective observer you posited becomes a problem as he would interact with every quantum event in the universe drastically changing outcomes.
29 Aug 13
Originally posted by DeepThoughtThe 'observation' does not have to come from a conscious mind, right?
In Twentieth Century Physics the observer takes a central role. In Newton's universe you have an absolute space and a separate absolute time, physical influences can travel instantaneously. In this universe it is possible to order events in a universal way; the state of an observer is not expected to alter what they see, specifically all observers will ...[text shortened]... m as he would interact with every quantum event in the universe drastically changing outcomes.
It could be an instrument taking a voltage reading or some such just as well couldn't it? Isn't the gist of it the acting on the reading that changes the states?
29 Aug 13
Originally posted by sonhouseFor whose benefit is the device making the measurement? If the information isn't recorded and retrieved by a conscious entity then no experiment has taken place. It's an interesting question, one could have the device only report summary statistics. With relativity it doesn't matter, the observer doesn't need particularly to be conscious, it's enough for them to be able to see and report their results. Relativity is classical in the sense that all the events happen whether we observe them or not, and the approximation that observations and test masses do not alter the physics up to a given precision is good. In quantum mechanics this stops working, any act of measurement has a profound impact on the thing measured; worse you get this technological version of the old thing about trees falling over in the woods not making any noise if no-one is there to hear it.
The 'observation' does not have to come from a conscious mind, right?
It could be an instrument taking a voltage reading or some such just as well couldn't it? Isn't the gist of it the acting on the reading that changes the states?
Suppose we do a version of the EPR experiment. We have two observers waiting for photons to turn up and a method of measuring their spin, they are stationary with respect to the laboratory. We have someone to prepare the initial state to whom all results are reported and whose frame of reference is the laboratory frame and two extra observers in fast moving frames of reference who also get the results reported to them (by a signal at the speed of light). The atom decays and we get two photons. In the laboratory frame of reference the two photons turn up at each of the observers at the same time and they collapse the wave-functions and find the spins. The results of the two measurements will be consistent, which means that the entangled particles somehow manage to agree what states to collapse into. This implies infinitely fast signaling. Where this starts to get weird is that as far as the two fast moving observers are concerned the observation events did not happen at the same time, and I've set it up so that they disagree about order of events. So in one of these frames of reference one observer "causes" both wave-functions to collapse and the "effect" is that the second observer sees a result consistent with the first observer's result; in the other frame it's the other way round. So, for entangled particles all our common sense ideas about causation go away. The problem of what constitutes a viable observer is therefore paramount. We believe that consciousnesses are viable observers, some have taken them to be the only entities capable of doing this; this isn't the only view as Penrose claims that interaction with gravity is enough to collapse a wave-function.
29 Aug 13
1 edit
Originally posted by DeepThoughtI wasn't suggesting this universal observer is the only one or would influence what it is observing. I just tossed it in to be a point of reference and to help create a scenario that can be easily visualized.
In Twentieth Century Physics the observer takes a central role. In Newton's universe you have an absolute space and a separate absolute time, physical influences can travel instantaneously. In this universe it is possible to order events in a universal way; the state of an observer is not expected to alter what they see, specifically all observers will m as he would interact with every quantum event in the universe drastically changing outcomes.
Planck time is too small for anyone to confirm what may or may not be happening at that scale. I'm not against exceptions to rules because they serve to confirm rules rather than to disprove them. But if you were talking about time travel at that small a scale then there is not much I can do with that. In theory (at that level) it could be chaotic enough for tiny leaps back into time and even short jumps into the future. Not that long ago you alluded to how averaging out of realities is how this larger reality might be formed... and by larger reality I mean the reality we are aware of, are a part of, and move around in. We don't act on or react to peculiarities that may (or may not) exist at the quantum level, so when I talk about time travel I'm talking about something we could be aware of if we somehow managed to do it.
http://en.wikipedia.org/wiki/Planck_time
29 Aug 13
Originally posted by DeepThoughtoops, I missed seeing one of your previous messages... I've lost track of who said what to whom and when. I think Losing the Thread applies more to me than it does to you, so I'll come back later to look at all of this again in a fresh light.
In Twentieth Century Physics the observer takes a central role. In Newton's universe you have an absolute space and a separate absolute time, physical influences can travel instantaneously. In this universe it is possible to order events in a universal way; the state of an observer is not expected to alter what they see, specifically all observers will ...[text shortened]... m as he would interact with every quantum event in the universe drastically changing outcomes.
I took a quick look at the message I missed reading before, but I didn't see anything I have a problem with... or disagree with. So I'm curious... where exactly is there disagreement, or what have I failed to understand?
29 Aug 13
Originally posted by DeepThoughtIt depends on how you define the word "sound", as in the sound a tree makes when falling in a forest. If you define sound as only being something heard, then a tree falling in a forest makes no sound if no one is there to hear it. But if you define sound as being sound waves, and how the air is affected, then it doesn't matter if anyone is there to hear that sound or not... either way it makes a sound.
For whose benefit is the device making the measurement? If the information isn't recorded and retrieved by a conscious entity then no experiment has taken place. It's an interesting question, one could have the device only report summary statistics. With relativity it doesn't matter, the observer doesn't need particularly to be conscious, it's enough ...[text shortened]... Penrose claims that interaction with gravity is enough to collapse a wave-function.
An act of observation on the quatum level can affect what happens, but there again I think it's useful to define in greater detail what we mean by observaton. Is the observation passive, or do we need to do something (act on an object being observed) before an action or object can be seen?
29 Aug 13
Originally posted by lemon limeNo, I mean sound waves - I'm not talking about the physiological response. The point is that we extrapolate from the cases where someone is present to confirm that sound waves are created when a tree falls over, to cases where no one capable of confirming that a sound was made were present. In classical physics (even relativity with its weirdnesses) that is always assumed to be possible. In quantum physics it isn't.
It depends on how you define the word "sound", as in the sound a tree makes when falling in a forest. If you define sound as only being something heard, then a tree falling in a forest makes no sound if no one is there to hear it. But if you define sound as being sound waves, and how the air is affected, then it doesn't matter if anyone is there to ...[text shortened]... o something (act on an object being observed) before an action or object can be seen?
I think your universal observer creates problems in both relativity and in quantum theory, basically it can lead you to incorrect pictures, such as a preferred universal ordering in time for events separated by space-like intervals.
30 Aug 13
1 edit
Originally posted by DeepThought...it can lead you to incorrect pictures, such as a preferred universal ordering in time for events separated by space-like intervals.
No, I mean sound waves - I'm not talking about the physiological response. The point is that we extrapolate from the cases where someone is present to confirm that sound waves are created when a tree falls over, to cases where no one capable of confirming that a sound was made were present. In classical physics (even relativity with its weirdnesses) th , such as a preferred universal ordering in time for events separated by space-like intervals.
I prefer to see it that way as well, but I never proposed this observer to be anything other than an abstract. And I never suggested we can apply the same experience of knowing (without seeing) how sound waves will occur on the macro scale to quantum phenomenon. But this hasn't prevented us from finding predictable patterns and outcomes. Sure, the same rules don't apply, but there's no reason they would have to apply. Averaging out of realities with as much activity as there is at that level insures the same outcomes will always occur at the macro level. The theory of large numbers confirms this... and in this case close enough really is good enough... it's good enough for me, and I'm a bit of a hard to live with nit picking perfectionist.
I'm so tired right now I'll probably look at this tomorrow and not understand one word of it. So feel free to rip it apart and toss it back in my face... I don't care.
01 Sep 13
Originally posted by KazetNagorraThat's right, but observers don't determine the order of cause and effect. They are simply observers.
The existence of a universal observer would mean that for some (other) observers, causes can occur after the effect. As such, the idea is incompatible with relativity.
The universal observer is like the man who can see the entire elephant. The various blind men surrounding the elephant are limited to seeing (with their hands) the different parts of the elephant, and the relative differences in what can be observed will determine what is observed. I know this is a terrible analogy, but I don't have a lot of time* right now so maybe I'll think of a better one later.
*relative time
01 Sep 13
Originally posted by lemon limehttp://en.wikipedia.org/wiki/Relativity_of_simultaneity
That's right, but observers don't determine the order of cause and effect. They are simply observers.
The universal observer is like the man who can see the entire elephant. The various blind men surrounding the elephant are limited to seeing (with their hands) the different parts of the elephant, and the relative differences in what can ...[text shortened]... lot of time* right now so maybe I'll think of a better one later.
*relative time
01 Sep 13
Originally posted by lemon limeThis video makes reference to a universal observer:
That's right, but observers don't determine the order of cause and effect. They are simply observers.
The universal observer is like the man who can see the entire elephant. The various blind men surrounding the elephant are limited to seeing (with their hands) the different parts of the elephant, and the relative differences in what can ...[text shortened]... lot of time* right now so maybe I'll think of a better one later.
*relative time
&list=PL59FD389070AA0F00&index=15
The Instructor
01 Sep 13
12 edits
Originally posted by KazetNagorraI really like that link a lot 🙂 .
http://en.wikipedia.org/wiki/Relativity_of_simultaneity
It says:
“...In physics, the relativity of simultaneity is the concept that distant simultaneity – whether two spatially separated events occur at the same time – is not absolute, but depends on the observer's reference frame.
According to the special theory of relativity, it is impossible to say in an absolute sense whether two distinct events occur at the same time if those events are separated in space, such as a car crash in London and another in New York. The question of whether the events are simultaneous is relative: in some reference frames the two accidents may happen at the same time, in other frames (in a different state of motion relative to the events) the crash in London may occur first, and in still other frames the New York crash may occur first. However, if the two events are causally connected ("event A causes event B" ), the causal order is preserved (i.e., "event A precedes event B" ) in all frames of reference.
If we imagine one reference frame assigns precisely the same time to two events that are at different points in space, a reference frame that is moving relative to the first will generally assign different times to the two events. ...”
-That puts an interesting constraint on how we should define causality as well as, indirectly, helps make nonsense of the notion that there must be absolute time.
It also says:
“...It was Albert Einstein in 1905 who abandoned the (classical) aether and emphasized the significance of relativity of simultaneity to our understanding of space and time. He deduced the failure of absolute simultaneity from two stated assumptions:
1, the principle of relativity – the equivalence of inertial frames, such that the laws of physics apply equally in all inertial coordinate systems;
2, the constancy of the speed of light detected in empty space, independent of the relative motion of its source.
...”
It is just so clever the way those scientists can deduce things like that, isn't it!
I think that is a good classic example of what REAL science is all about.
Just think, without any science, we would be oppressively and permanently kept totally ignorant in some sort of truly ghastly 'dark age' and will never see or know the brilliant blinding light of truth.