I am new here and have not yet read every post in this thread ... but the concept of time is something I have some thoughts about. I must jump into the forum some where - so - this is it
Time ... exists in our heads (as someone here said) it is definitely a human experience. It is a function of dong a comparison between a past experience (memory) and a present experience.
All there is - is the present moment. A dynamically changing experience. And if we did not have the capability of memory - all we would know (fresh at each instant) is the here and now .. with no other reference point - we can not have an experience of time.
Q: Does 'time' exist?
A: Yes. But only as a human experience.
Q: Did time exist before humans existed?
A: No it did not.
There are two tricks to understand the answer to the question.
The first is to realizes that time is specifically a human experience - like sound. Like touch. Like taste. Like sight. Time does not exist until there is a human with perception and memory. The comparison of our current perception ... with our memory ... gives us our experience of what we call 'time'.
When we hear sound - the sound itself does not exist "out there" - our experience of sound is that it is the result of the transduction of what-we-perceive (waves etc..) via the sense of hearing (ears) into a human experience.
Let us trace the path.
The dog barks... which means air rushes through his throat (no sound yet) setting up vibrations (no sound yet) in the air which travel as a wave (alternate compressed air) to our ear drums (no sound yet) and that sets off impulses in our nerves which carry electrical signals to our brains (no sound yet) .. and somewhere somehow (we know not how) that soundless energy is then transduced into an existential experience that we humans have (NOW we have sound!).
The second 'trick' is in the definition of what it is to exist (to-exist) which defines an act (action) that a human experiences. Existence (to-exit) is also (as sound is) a human experience .. traduces to us by way of our senses. Without the involvement of our senses ... existence ... is only a theory and a contingent potentiality with no reality yet. It requires our human senses and the transduction of that into an existential human experience (we can call it observation as in the 'measurement problem' of quantum psychics) to have something ... to-exist.
Put the cat inside the box and ask the question "Does the cat exist inside the box?" and the answer is most definitely ...
No.
!!!
WHY?
... because ... while we can predict that we will experience the cat again when the box is opened ... for the span of time in which we do not directly experience the cat ... the cat does not exist! Why? How can I say that???
Because existence is a condition that is defined by ... having a human experience.
Perhaps the cat IS in the box for the span of time that we can not see into the box to confirm that fact. Perhaps the cat was sent off into another dimension and only came back at the moment we re-open the box. Perhaps the cat fell through a trap door that we did not know about and when we open the box the cat is not there. Perhaps god performed a miracle and vanished the cat... the point
is that the existence (to-exit) of the cat is predicated on our ... human experience ... of it. The box (blocking our senses) makes it so that we do not have an experience of the cat - no experience = no existence. It is simple if we use the words correctly.
To use the word 'exist' in any other way than to describe a human experience ... is a misuse. However ... we do this all the time due to the practical situation that it makes life easy. It is a theory that seems to work pretty well for us in daily life even if we are sometimes wrong.
We can also use instruments or thought to postulate the existence of something that we have no direct experience of - for example the obits of other planets postulated the existence of Pluto ... but until we actually observed it Pluto did not exist - the only thing that
did exist was our theory that Pluto existed.
All we have to do is use the word 'exit' correctly.
Someone sez "I am going to the store." but gets hit by a car and never gets to the store. The reality is that he was never going to the store .. he was going out to get hit by a car (however he did not know that), But we could perhaps argue according to his own intention verses the final and real results.
For ANYTHING to exist - it must have a location. Which is another way of saying that it must be definable by its limitations. For anything to=exist that thing must be limited ... according to the capability of our senses. These limits (which are really according to our senses only) define its - location - from other things.
And the limitations of anything - are limitations only according to our own human sense perceptions ... and THAT fact pins it tightly and directly to - a human experience.
Our human sense perceptions can be augmented by instruments (telescopes, microscopes, math, what have you) but the key here again is that these instruments traduces to our senses - an experience! These instruments transduce something into our range of sense perception and by doing that it gives us an expereince.
Q: Does time - exist?
A: Yes. But only as a human experience.
Q: Did time exist before there were any humans? (after all there were other animals before humans)
A: Time IS a HUMAN experience.
That question can not be answered for two reasons (and it is not that we cant; find and answer - it is that no answer esists for that question - the question itself can not be asked).
What other animals experience ... I do not know. There is no way to transfer their animal expereince (sensnes /brain / etc) to me. While some of our senses are shared in physiological make up - the minds, memories, etc.. (the psychology) and MEANING oor any expereince - are far too dissimilar.
It is impossible for me to know the experience that even the closes animal (ape) might have of what I might call 'time'. It is also impossible for an ape to know my human experienced of time. The animal expereince and the human expereince can be like - but they can not be the same.
I would expect that higher animals do have an experience that can be likened to my own experience of 'time' - but - it is not a human experience they are having .. and 'time' is defined as a specifically
human experience.
Which leads one to the next question...
Q: Can the past - be changed?
First off - this question is not legitimate. It is like asking "Can blue be up?" or "Can up be a solid?" ... it simple is apples and oranges.
BUT - in the sense intended for the question .. the answer is ... yes. The past does change. It changes often. It can 'change' depending upon the choices we make at every present moment.
What has been observed (now in memory) can definitly change in its causality. And the reality of anything is dependednnt upon its causality. A simle way to say this would be to say that the meaning of anything can change. Because casuality is entirely dependent upon (you guest it) a human expeeince of - meaning. What it MEANS to my human mind.
Q: But how can it change? when something that has happened psychically - seems to be done - accomplished - and unchangeable?
The answer to that question goes back to the fact that to-exist depends entirely upon a human experience and what the core of that experience is .. is what it means to us humans.
Both the past and the future - are contingent potentialities - which depend entirly upon the freedom of 'me' in the present moment (or the lack of that freedom).
If anyone is interested in how and why I say that the past can be changed ... I will explain that by a simple thought experiment involving a table and a falling line of dominoes.
Thank you for taking the time to read this. I invite objections.
-Raymond