What is time?

[Qfwfq]

I partly agree, but:

Originally Posted by infamous

Time is only the memory of passing events.

I'd say that time is only passing events while the memory of them is how we are aware of time and have a notion of it. There are animals that, while able to perceive their surroundings in order to find food and flee peril, appear to have no memory or ability to learn. They don't survive if they don't have the right instincts and a smarter animal can easily deceive them. To them, presumeably there's no such thing as time, to us there is.

Does time exist or not? A stone could even less have a notion of time but that doesn't mean it doesn't exist.

[CraigD]

This thread seems to have grown a strong current suggesting that the conscious perception of time (eg: by a human mind, but not by a rock) is an important aspect of the largest concept of “time”, tempting me to throw my own 2 cents into this stream.

I’ve long been a fan of the psychologist Abraham Maslow, most well known for his pyramidal “hierarchy of human needs”. At the top of this pyramid lies “actualization”. It is here that Maslow starts to get weird and metaphysical – up to that point, the hierarchy describes mechanisms that can be measured by observable behavior, and potentially explained by relatively simple neurology. The lower parts of the hierarchy can be applied sensibly to non-human, “dumb” animals, but actualization seems reserved only for “pinnacle of cognition” animals like H.Sapiens.

Rather than describe actualization in terms of simplified dynamic interaction, the way he did with the lower needs, Maslow just spewed forth lists of traits and examples of self-actualized people, paying homage to folk he admired like Einstein and Eleanor Rosovelt. One of the traits he described was a “sense of personal place in history,” meaning the intuitive, subjective sense that the timelines one reads in books (including, even, Cosmology) and ones personal timeline (eg: waking, doing chores, aging, etc) are part of the same thing, a thing one could reasonably term “time”.

There seems to be a strong link between the subjective awareness of the passage of time (that is, having a mind that models external reality with time as a distinct, manipulable axis) and the hard-to-impossible-to-define concept of consciousness.

The subjective sense of time is hard to define, but seems to be very important.

[Kriminal99]

My approach to this question is to look at the source. Time is the difference between events that a consious entity is capable of percieving. If you sat somewhere and absolutely nothing changed (including any internal clocks in your head or any biological processes that you could percieve) there would be no time. Its just measuring the duration/frequency of events in comparison to the frequency of other events.

[Southtown]

Obviously time is required for perception, even if only defined by passing events. But it is also a factor in the physical processes that bring about the platform for an observer to exist in the first place. Time is required for perception, not vice versa.

[Kriminal99]

Originally Posted by Southtown

Obviously time is required for perception, even if only defined by passing events. But it is also a factor in the physical processes that bring about the platform for an observer to exist in the first place. Time is required for perception, not vice versa.

Yeah but those processes might be able to occur without us being able to percieve them or giving us some subconsious ability to determine time. Any idea of time has still been created by a consious mind and cannot be seperated from the function of perceptions which define it. There might be something outside of our mind occuring that controls what we percieve, but the ideas in our mind are NOT the same as this "man behind the curtain". My personal experience is that if you want your reasoning to allow you to predict reality, you must make sure that your ideas do attempt to contain anything that is beyond how they are realized in our mind. That is we must recognize our primitive means of modeling concepts like time for what it is.

If you follow this reasoning and accept that as the subconsious definition of time, the statement you just made was: "The difference between events that I percieve is required for us to percieve the difference between events" Quite an observation, but it does not defeat the purpose of my claim. The purpose is to recognize that if you alter when we percieve events you alter our perception of time because our idea of time is dependent on when we percieve things. This is the understanding to start with before approaching things like special relativity.

You may want to believe that there is time that has nothing to do with your consiousness, but since you only experience things from your consiousness what reason do you even have to believe that is the case?

[CraigD]

Originally Posted by Southtown

… Time is required for perception, not vice versa.

I can find no fault in Southtown’s reasoning.

Consider this thought experiment:
Imagine a universe containing only mass and momentum bearing fermions, no force mediating bosons. Suspend questioning if this is possible under the Standard Model (+ gravity), which predicts no fermion that doesn’t spontaneously produce at least W bosons, Z bosons, (and gravitons) – the point is to imagine a universe where particles cannot in any way interact. These particles would be, in a sense, related to one another, in that they would obey the Pauli exclusion principle, prohibiting them from colliding, etc., but this relationship would be a static one of their quantum wave functions. Unlike the actual universe, these wave functions would not change over time.

They would still have implied momentum vectors, so, in a precise, deterministic way, the most likely position of each particle would change with time as measured from any inertial frame (Special Relativity would still apply, though, in the absence of gravity, General Relativity would be irrelevant).

In this universe, increases (or any change) in total entropy would be impossible. Information processing of any kind would be impossible, so perception would be impossible. Yet time would be a well-defined and required concept in describing this universe. Therefore time would exist without perception.

[Southtown]

Originally Posted by Kriminal99

You may want to believe that there is time that has nothing to do with your consiousness, but since you only experience things from your consiousness what reason do you even have to believe that is the case?

What reason do we have to believe that anything we see, think, or feel is actualized? What you're saying is entirely possible, but it defeats the purpose of all perception utterly.

[Kriminal99]

Originally Posted by CraigD

I can find no fault in Southtown’s reasoning.

Consider this thought experiment:
Imagine a universe containing only mass and momentum bearing fermions, no force mediating bosons. Suspend questioning if this is possible under the Standard Model (+ gravity), which predicts no fermion that doesn’t spontaneously produce at least W bosons, Z bosons, (and gravitons) – the point is to imagine a universe where particles cannot in any way interact. These particles would be, in a sense, related to one another, in that they would obey the Pauli exclusion principle, prohibiting them from colliding, etc., but this relationship would be a static one of their quantum wave functions. Unlike the actual universe, these wave functions would not change over time.

They would still have implied momentum vectors, so, in a precise, deterministic way, the most likely position of each particle would change with time as measured from any inertial frame (Special Relativity would still apply, though, in the absence of gravity, General Relativity would be irrelevant).

In this universe, increases (or any change) in total entropy would be impossible. Information processing of any kind would be impossible, so perception would be impossible. Yet time would be a well-defined and required concept in describing this universe. Therefore time would exist without perception.

How does this differ from saying "If time existed seperate from perception, time would exist seperate from perception"? One could much more easily say "If a clock exists outside of my mind, then time exists outside of my perception". But A) There is no way to prove it and B) your idea of the time is dependent on your observations not on the clocks external existence.

Originally Posted by Southtown

What reason do we have to believe that anything we see, think, or feel is actualized? What you're saying is entirely possible, but it defeats the purpose of all perception utterly.

No it doesn't in this case. If you say a dog doesn't exist outside of your perceptions, then you are saying that a particular sack of molecules doesn't exist which is something that is pointless to speculate about. What I mean what I say time doesn't exist outside of your mind is that it is dependent on preception itself. This has nothing to do with the first case, the idea of a dog is a function of certain perceptions not perception itself. The dogs possible nonexistence is not something we could deal with if we knew it was true therefore it is irrelevant. Time's dependence on perception would be very signifigant to us if it were true.

[CraigD]

Originally Posted by Kriminal99

How does this differ from saying "If time existed seperate from perception, time would exist seperate from perception"?

My claim is not conditional. I’m saying “time exists separate from perception”, no “ifs”.

Also, I’m trying to make the statement using fundamental physical terms and concepts, steering clear of “softer”, more philosophical concepts such as “perception”. My semantic “leaps of faith” are limited to the implication that information processing is a prerequisite for perception – not an unreasonable assumption, I think.

One could much more easily say "If a clock exists outside of my mind, then time exists outside of my perception".

I wanted to more explicitly define what is meant by a “clock”. To wit, by implication, in the context of my thought experiment: a clock is any formal system with a term labeled “time”.

But A) There is no way to prove it

I think there is, though not currently by means of a realization of my thought experiment – creating new universes is a bit beyond the current state of the experimental art!

A quantum computer depend explicitly on isolation from interaction with – that is, perception by – outside observers of either a human or mechanical kind. It is, for a short interval of time, like a single particle in my thought experiment, unable to exchange bosons in a significant way with anything outside of itself. If time ceased to exist in the absence of perception, then the quantum state of a quantum computer would be identical at the end of its run to at its beginning, and it would compute nothing. Yet, though quantum computers are still in their infancy, and not yet able to perform very useful computations (a few qubits, able to, for example, factor 15 into 3 * 5 – see this 2001 IBM research article - is the current state of the art, and further progress is proving difficult) they actually do appear to work.

and B) your idea of the time is dependent on your observations not on the clocks external existence.

See above. Despite the need to observe the state of a quantum computer after its run to know the result of its computation, the actual computation can only have occurred if the passage of time within the quantum computer was not observed. So, I would say, the measurement of the passage of time is dependent both on my observations and on the clock’s external existence.

[dasraiser]

hi folks

ok i'm a bit late in this thread, but here's my (English coinage) two pence.

I believe that time is the measured distance between a chain of physical events, and with this in mind, I've a simple observational experiment.

I see the world around me though my eyes in an XY plane with a 3rd perception of depth or time: depth being the measurement of me to the object and time being the physical properties the actual event take to reach me ,ie the time light from a bulb or sound from my speakers take to reach me.

Conscious observations of time would in the same sense be the memory's of "living in the moment", but measured as a sequence of remembered events spanning a period of time.

On a side step, if time travel to the past is possible (by whatever means), i see a problem that concerns physics and time... if time runs backward along with physics then any traveling observers would not recognize anything different, they by definition would still be held by gravity! and the apple would still fall!!!! so is it really possible to say time travel to the past or would i have to say traveling physical to the past?

oh well, still contemplating, still learning.

regards