Ontology of time

[md65536]

You didn't. No problem. It is good to raise yet again the questions, "can the past be changed (or even 'visited')?"... and "can the future be visited?"

I would really like to hear from those who say "yes" to either or both vis-a-vis my last post.

Alright I'll give it a shot because I'm obviously a glutton for punishment.

I'm not a physics expert.

 

 

 

 

If you have a simple enough system (say, two simple particles), its state (ie. the state of the particles including relative to each other) may return to the same state it had at some point "in the past".

If the two states are theoretically indistinguishable, and there is no possible measurement of time (within the system) elapsed between the current state and its previous state, then there may be no difference between saying that the particle traveled "forward in time" or backward, in an oscillation, or that it moved forward but then returned to the past time. Deciding that it is one but not the other involves attaching false meaning to the physics, and is a common pitfall in metaphysics.

 

This applies only to that one particle's time relative to the other particle. In a more complex system, the rest of the components can continue on independently... it is unlikely that a particle will ever return to the same state relative to all the other particles in -- for example -- an egg. In fact it's statistically impossible. It's the laws of statistics that make a fried egg a one-way process, not some fundamental universal physical aspect of time that applies at every scale.

 

The statistical laws can be encoded as physical laws with the concept of entropy. It is entropy that prevents a fried egg from becoming unfried. If your description of time is not separated from your description of entropy, then time is one-way. If you separate the two concepts, and talk about time independently of entropy (which you might only be able to do in a small enough, simple enough, and/or perhaps a meticulously organized enough system), then it's possible to have things moving backward and forward through time without problem.

 

 

 

 

 

Philosophically, if you consider the passing of time to be "moving into the future", then manipulation of time dilation could be considered time travel to the future. That is, if all movement "through time" involves traveling through time, then it can be done at different rates (forward only though, when entropy is involved).

Since you can't go backward, you can't "visit" the future with the implication of "returning to the present".

Whatever your concept of time-travel might be, you'll always be in "your present". All that says is "wherever you go, there you are."

Edited November 11, 2011 by md65536

[moth]

The delayed choice quantum eraser seems strange to me because at the time the photon that will make an interference pattern (or not) hits the target the entangled photon has not been directed to erase (or not) the path information. How does the photon "know" where to land on the target before the path info has been erased or preserved? How can an event that occured in the past be affected by current events?

[md65536]

The delayed choice quantum eraser seems strange to me because at the time the photon that will make an interference pattern (or not) hits the target the entangled photon has not been directed to erase (or not) the path information. How does the photon "know" where to land on the target before the path info has been erased or preserved? How can an event that occured in the past be affected by current events?

I don't think that that experiment is on-topic nor would I expect a satisfying answer here. It'd probably be best to ask in a new thread in the Quantum Theory forum instead of Speculations.

 

But I think the answer to your question is essentially that the intuitive aspects of time, regarding that experiment, involve causality. The experiment doesn't violate causality. So if you understand why causality isn't violated by the experiment (I couldn't explain it because I only have a vague understanding, just enough to accept that it's true!), then you'll probably find that while the experiment isn't explained by "common sense" (aka. causality in this case), it also doesn't contradict it.

Edited November 11, 2011 by md65536

[moth]

It reminds me of Schrodinger's cat, the cat is alive and dead until the contents of the box are observed - and the photon interferes and does not interfere until the coincidence data is observed. But the data has all been recorded previously and the superposition is resolved by the looking. Maybe it's off topic but it suggests something about time to me even if I can't express what.

nice avatar by the way. eraserhead is underrated.

 

 

edited for punctuation

Edited November 12, 2011 by moth

[owl]

How can an event that occured in the past be affected by current events?

It can't.

 

It reminds me of Schrodinger's cat, the cat is alive and dead until the contents of the box are observed - and the photon interferes and does not interfere until the coincidence data is observed. But the data has all been recorded previously and the superposition is resolved by the looking. Maybe it's off topic but it suggests something about time to me even if I can't express what.

nice avatar by the way eraserhead is underrated

Sometimes (often times) theory has very little to do with reality. In reality a cat is either dead or alive. Observation has nothing to do with it.

[moth]

Observation would seem to have everything to do with whether a photon "looks" like a particle or a wave.

The experiment we're talking about has been perfomed and the results are known.

The question is how does the result fit in your theory of "now". Does an event occuring "now" have a single outcome or many outcomes which can be affected by later events?

[owl]

Observation would seem to have everything to do with whether a photon "looks" like a particle or a wave.

The experiment we're talking about has been perfomed and the results are known.

The question is how does the result fit in your theory of "now". Does an event occuring "now" have a single outcome or many outcomes which can be affected by later events?

An event occurring now IS the outcome, having already been caused by events leading up to the present. Future events can not effect an occurrence that is already happening now, already caused as above.

It's not like "time" can be "fast forwarded" into the future or "rewound" back into the past.

 

Btw, on another subject, it is very strange to be still taking fire in a thread "the present time" on things like my definitions (not physics) in which I am not allowed to reply unless it's physics related.

Swansont said:

But as soon as the discussion turns

to anything that contradicts relativity or is based on philosophy, you are off-topic.

 

Like what a psychologist is (granted, blame md) or what time is when referred to as an entity in relativity, as in "block time" or relativity's "block universe" in which everything that has existed or will exist is somehow existing now?

I think that when I return from my weekend I will start a thread on the philosophy of science (in the Philosophy section, of course) with a focus on understanding relativity's basic *assumptions* about what time, space, and spacetime actually ARE in the real world. Maybe there I will be allowed to "contradict relativity" as per it's "block universe" assumptions about time, etc.

I think I will call the thread, "Is Philosophy Relevant to Science?"

Edited November 12, 2011 by owl

[moth]

I don't have a clue how time works I'm just asking questions of you because you claim you do, or at least you claim to know how time does not work.

 

An event occurring now IS the outcome, having already been caused by events leading up to the present. Future events can not effect an occurrence that is already happening now, already caused as above.

It's not like "time" can be "fast forwarded" into the future or "rewound" back into the past.

 

Are you saying the delayed choice quantum eraser experiment results should be ignored because they don't fit your concept of "now" or are you saying the result is wrong?

[md65536]

Btw, on another subject, it is very strange to be still taking fire in a thread "the present time" on things like my definitions (not physics) in which I am not allowed to reply unless it's physics related.

You posted erroneous information.

You didn't post any retractions or corrections, and the misinformation remained.

People were confused by accidentally taking it at face value.

Another user was then compelled to point out the error.

The rules prevent you from repeating the misinformation.

Which part do you find strange?

 

 

I'm getting off topic... I'll try to get back to ontology of time...

 

I don't have a clue how time works I'm just asking questions of you because you claim you do, or at least you claim to know how time does not work.

 

 

Are you saying the delayed choice quantum eraser experiment results should be ignored because they don't fit your concept of "now" or are you saying the result is wrong?

I second this sentiment.

 

I'm wrong to say the experiment is off-topic -- that assumes that there is no on-topic explanation of the experiment.

But I'm actually quite interested in how the results of the experiment might be explained using (or consistent with) the ontological arguments.

 

 

[owl]

I don't have a clue how time works I'm just asking questions of you because you claim you do, or at least you claim to know how time does not work.

Are you saying the delayed choice quantum eraser experiment results should be ignored because they don't fit your concept of "now" or are you saying the result is wrong?

First, I am not an expert in quantum physics. For instance, it remains very mysterious to me how "entangled particles" interact at a distance. Also I don't understand how it is that the experimental design here claims to demonstrate, as you said, that "... an event that occurred in the past (can) be affected by current events?" I said, "it can't" because that would violate causality. Present events do not cause events that have already happened (past events) to change.

 

But at the very basic level, the ontology of time examines what "it" is. Everything moves. As anything moves from "here to there" we say that "time elapses." But that does not mean that time is an entity or medium of some kind, a "timescape" through which one can "travel." Physics folks like to say that "time is that which clocks measure." But if there were no clocks or intelligent beings measuring event duration, everything would still be in motion, and "time would elapse" as everything moves, whether "as a whole," cosmologically speaking or in whatever specific part, like say one Earth revolution or an orbit around the Sun... or photons traveling through slits to hit a wall. There is no "rewind" to make the past present again. And time is not a medium through which things move. Again, as things move "time elapses."

In any case, on whatever scale, including the quantum eraser experiment, the past has already happened and can not be changed... can not become the present.

[moth]

I'm not an expert of anything so you may be correct and I'm not making sense, but I appreciate the opportunity to discuss this issue.

Is there an ontology of causality? I'm not sure the experiment violates causality because if observation is what determines whether one outcome or another (particle-like or wave-like)is seen, then the observation seems to me to be part of the cause.

But the question remains - if "now" is the only time how do the photons "know" where to interact with the detector?

 

In any case, on whatever scale, including the quantum eraser experiment, the past has already happened and can not be changed... can not become the present.

 

There's always the "many worlds interpretation" but that seems to introduce more complications than it resolves.

[owl]

Moth:

Is there an ontology of causality?

 

Ontology examines what exists, applied to whatever. Causality exists as "cause and effect." Ontology employs reason as one of its tools. Reason dictates that causes precede effects (unless time can "run backwards," which it can not.) As I said, "Present events do not cause events that have already happened (past events) to change." Also, "...the past has already happened and can not be changed... can not become the present."

If you think that this experiment demonstrates that a present event effected a past event, please explain how you see that being verified. I don't see it.

 

You say:...

then the observation seems to me to be part of the cause.

We observe what is happening, what has already been caused. For instance, in the "Schrodinger's cat" example, the cat in the box is either dead or alive, but we don't know which until we open the box and observe. That observation does not effect whether the cat is alive or dead, due to whatever cause, independent of the observation.

[moth]

Here's how i see the experiment. Please let me know if you disagree

 

1 photon is generated

2 photon interacts with double slit

3 photon interacts with crystal resultng in two photons

4 the two photons interact with a prism that causes them to diverge

5 one photon is directed to a detector(call it detector "a") the other is directed to a prism that is placed to refract the photon on two paths depending on which slit it passed through

6a the photon encounters a beam splitter where it is reflected to a detector (preserving the path info)

6b the photon encounters a beam splitter and is transmitted to a mirror and another beam splitter so when the photon is detected there is 50-50 chance it was reflected or transmitted by the splitter(erasing the path info)

7 the detectors are all connected to a coincidence counter to correlate the photons seen at detector a with the photons seen at the other detectors

 

 

the path length to detector "a" is shorter than the path lengths to where the which slit info is preserved or erased so at the time the detector "a" photon is seen the path info has not been preserved or erased.

 

it is the path info which causes the detector "a" photon to appear as a particle or wave

It appers the effect (particle or wave at detector "a") preceeds the cause (preserved or erased path info)

 

I found this paper with another example of retrocausality (not an appeal to authority I'm just glad I'm not alone in my thinking).

Couple this with the knowledge that QM has all of the attributes to accommodate backward causation. One would be hard pressed to develop any other practical theory more compatible with backward causation. Once backward causation is accepted, many straightforward consequences of it were examined and it was found that some of the strange features of QM become less strange, for example the delayed choice experiment.

[owl]

Moth:

It appears the effect (particle or wave at detector "a") preceeds the cause (preserved or erased path info)

 

This is highly technical, and I would need to study the experimental design in minute detail to find the (presumed*) fallacy in the assumption that it demonstrates an effect preceding its cause. * The later does violate causality (causes always precede effects.) It assumes that time is an entity or medium which can 'run backwards' and reverse what precedes what.

I suspect that the answer lies in the deep mystery of how entangled particles, including photons, "keep in touch" at a distance, i.e., that info seem to travel between them instantaneously, in "no time."

[moth]

I suspect that the answer lies in the deep mystery of how entangled particles, including photons, "keep in touch" at a distance, i.e., that info seem to travel between them instantaneously, in "no time."

Take a look at the paper from the link in my previous post. Wharton describes how backwards causation can explain the EPR paradox. You might also have a look at Wheeler-Feynman absorber theory. It's more a mathematical construct than a physical manifestation but it does involve time running backwards.

[owl]

Take a look at the paper from the link in my previous post. Wharton describes how backwards causation can explain the EPR paradox. You might also have a look at Wheeler-Feynman absorber theory. It's more a mathematical construct than a physical manifestation but it does involve time running backwards.

Do you understand that "mathematical constructs" require physical referents to be relevant to the empirical science of observable phenomena?

Do you have an ontological analysis of what time IS that "it" can "run backwards?"

The experiment you cite must assume that time is an entity or medium which can 'run backwards' and reverse what precedes what.

 

My ontological understanding of "time" has concluded that it is not such an entity, but I may yet study the experiment in enough detail to see what the claim is based on.

 

Note: Much of the belief in time travel is based on "time dilation" as if time were "something" detected and measured by clocks. The fact that clocks slow down when accelerated to high velocities does not mean that "time slows down", for instance. The slowing of physical processes, probably including human aging, does not equate to "time travel."

[md65536]

The experiment you cite must assume that time is an entity or medium which can 'run backwards' and reverse what precedes what.

[...]

Note: Much of the belief in time travel is based on "time dilation" as if time were "something" detected and measured by clocks.

You keep using those words. I do not think they mean what you think they mean.

 

 

 

 

I'm not an expert of anything so you may be correct and I'm not making sense, but I appreciate the opportunity to discuss this issue.

Before you get too entrenched in scientific debate in the Speculations forum, you might want to brush up on a thread like http://www.scienceforums.net/topic/58293-frame-of-reference-as-subject-in-subjective-idealism/, where you will see that owl has already soundly defeated the "theory" of relativity, and his claims remain untouched by even the most seemingly convincing of logical arguments. I know 26 pages is a lot to read through, but as owl really dislikes repeating the same thing over and over and over, it would be courteous to get up to speed on the whole "What is IT that is time?" field of study so that we can skip any questions that have already been answered and go full speed into the ontological discussion of the quantum eraser experiment.

[mooeypoo]

Note: Much of the belief in time travel is based on "time dilation" as if time were "something" detected and measured by clocks. The fact that clocks slow down when accelerated to high velocities does not mean that "time slows down", for instance. The slowing of physical processes, probably including human aging, does not equate to "time travel."

 

You talk as if "time dilation" is some "sci fi" concept that people simply "believe in".

 

The fact that clocks slow down when accelerated is experimentally proven -- it shows exclusively that time passed slower to one clock (that is moving) than to another (taht isn't moving). That's what we call time dilation. I'm not quite sure what you think time dilation is, but if you think that the evidence for time dilation doesn't mean time dilation exists,you need to supply alternate explanation for that phenomenon.

 

Accelerated clocks slow down *consistently* and correspond perfectly to the prediction (conceptually and experimentally, with math) made by relativity. What explanation do you give this phenomenon? How do you explain why the clocks repeatedly and consistently slow down?

[owl]

You talk as if "time dilation" is some "sci fi" concept that people simply "believe in".

The ontology of time investigates what "it" is, if anything, specifically in this case, 'something' besides the clocks themselves that slows down and speeds up in different circumstances.

If you think that clocks 'detect' time and that their slowing down means that 'time' is slowing down, then you have (relativity has) reifiied time.

I'll take your next paragraph a piece at a time.

 

The fact that clocks slow down when accelerated is experimentally proven

 

No question about it; well proven.

 

-- it shows exclusively that time passed slower to one clock (that is moving) than to another (that isn't moving). That's what we call time dilation.

The ontological 'leap' is from 'clocks slow down' as above, to 'time passes slower.' Physical processes, including clocks' 'ticking' slow down at higher velocities.

The 'time passes slower' statement assumes that time is some 'thing' which clocks detect, and that 'thing' slows down as above; not just the physical process of clocks 'ticking.'

 

I'm not quite sure what you think time dilation is, but if you think that the evidence for time dilation doesn't mean time dilation exists,you need to supply alternate explanation for that phenomenon.

I think that "time dilation" reifies time, makes 'something of it' besides the observable phenomena of clocks slowing down. This is why ontology challenges relativity's philosophical assumption that time is an entity which elapses at different rates.

 

 

Accelerated clocks slow down *consistently* and correspond perfectly to the prediction (conceptually and experimentally, with math) made by relativity. What explanation do you give this phenomenon? How do you explain why the clocks repeatedly and consistently slow down?

 

I do not pretend to explain why physical processes slow down at higher velocities. Only that it is clocks, not "time itself" which slow down.

[mooeypoo]

owl, isn't our definition of time "what clocks show" ? we're not talking about clocks we have at home, we are talking about atomic clocks. We define time according to them, so the clocks are not independent.

 

I see your point, but I think you're forgetting the above point. The fact an atomic clock slows down means the internal processes of the decay are slowing down. We define time with them, and they show us time slows.

 

What alternative explanation do you propose, other than "time slows" to describe "decay slows" ?

 

 

 

It seems we're moving away from conceptual discussion into an argument bout definition, which is nice, but is entirely different.

 

I think that "time dilation" reifies time, makes 'something of it' besides the observable phenomena of clocks slowing down. This is why ontology challenges relativity's philosophical assumption that time is an entity which elapses at different rates.

 

Not sure what you mean by that. Who treats time "as an entity"? Not relativity, really, it just uses the definition to describe what happens. What happens is that the action slows down in different frames of reference depending on speeds. We call that time, and we say 'time dilation' to describe it. I'm completely at a loss at what your point is, unless you're trying to redefine a definition just to make a point?

[A Tripolation]

I do not pretend to explain why physical processes slow down at higher velocities. Only that it is clocks, not "time itself" which slow down.

 

Then how do you explain muon decay?

[Appolinaria]

The ontology of time investigates what "it" is, if anything, specifically in this case, 'something' besides the clocks themselves that slows down and speeds up in different circumstances.

If you think that clocks 'detect' time and that their slowing down means that 'time' is slowing down, then you have (relativity has) reifiied time.

I'll take your next paragraph a piece at a time.

 

 

 

No question about it; well proven.

 

 

The ontological 'leap' is from 'clocks slow down' as above, to 'time passes slower.' Physical processes, including clocks' 'ticking' slow down at higher velocities.

The 'time passes slower' statement assumes that time is some 'thing' which clocks detect, and that 'thing' slows down as above; not just the physical process of clocks 'ticking.'

 

 

I think that "time dilation" reifies time, makes 'something of it' besides the observable phenomena of clocks slowing down. This is why ontology challenges relativity's philosophical assumption that time is an entity which elapses at different rates.

 

 

 

 

I do not pretend to explain why physical processes slow down at higher velocities. Only that it is clocks, not "time itself" which slow down.

 

well maybe when you increase velocity, you increase energy, and that bends space time temporarily until you slow down?

[A Tripolation]

well maybe when you increase velocity, you increase energy, and that bends space time temporarily until you slow down?

 

As your velocity increases, the energy of the system increases, but none of the rest of this or its implications is correct.

[Appolinaria]

As your velocity increases, the energy of the system increases, but none of the rest of this or its implications is correct.

 

 

 

Doesn't mass increase as energy (speed) increases?

 

 

I thought mass bent space time.

[mooeypoo]

Doesn't mass increase as energy (speed) increases?

 

 

I thought mass bent space time.

 

It's a good question, but start this in a different thread if you like, let's stick to topic on this one.