what is time exactly

dhiraje2002

the man who sees the world in his 50s the same when he was in 20s has wasted his 30 years.

Shooting Star

Why not? We may hit upon it by accident. Do we have to understand what goes on in our bodies to live?

Why so?

I've heard many people say that time dilation is valid for atomic time, not for biological time, whatever that means. They simply cannot accept the fact that humans may age at different rates.

Troels

The British Science writer Michael Hanlon has made som very interesting comments on this question in his book "10 questions science can't answer (yet)"

DLuckyE

If time is nothing more than a 'layer' of the current spacial state of the universe then it wouldn't matter if traveling back in time was possible. Since it'd be just like rewinding a tape, everything goes backward, and same things happens again going forward. Actually then nobody would even notice time was going backwards...

For all we know time goes back & forth all the time ;)

But then again, if that was true, time dilation wouldn't make any sense...

Just ignore me, I'm rambling, but still to me a 'static' universe seems to be the most logical even though that would mean free will is just something our mind makes us believe we have ;)

nanoWatt

Isn't this the same as trying to quantize time?

Kurdt

Philosophically a theory of time is unresolved. Most philosophers agree that time does exist but they haven't yet been able to determine what it exactly is. Most of what is known comes from the use of time in well established physical theories such as QM and GR and the nature of time is explored by looking at what these theories demand of the time variable. Perhaps it would suffice to say that time is a set of relations between events.

Here is a good article you may like to read.

http://www.iep.utm.edu/t/time.htm#H3

dbecker215

That was a good article, thanx. A lot of philosophy for one night though...

It's easy to see why time is still unresolved when so many won't even come to a common ground when trying to discuss possibilities. Philosophy's endless circles are daunting.

Shooting Star

Clever old A.E. cut through the gordian knot by saying, "Time is what you measure with a clock...". It turned to be quite fruitful, too.

lightarrow

So, I could use any clock, for example a sand glass? I don't think that's a good way to answer (infact he knew that was not an answer).

Jonathan Scott

A sand glass isn't a self-contained clock on its own, but a sand glass combined with a suitable planet to complete the mechanism would work as a clock for that purpose.

Kurdt

I think what Einstein omitted from that quote was the word ideal or accurate.

lightarrow

Absolutely

lightarrow

And how do you establish if a clock is more accurate than another if you still have to define what time is?

Shooting Star

Even I know that's not the answer, taken literally. But if you think about it, since we don't know much about time, this utilitarian approach is the best perhaps.

Sand glasses or pendulum clocks or anything which works on gravity is inadmissible as a clock in GR.

After many years of research, we have come to the consensus that atomic (or maybe subatomic) vibrations keep the best time. That's why we use those phenomena to measure time; or has it simply become a matter of definition that those keep the right time?

InfinateLoop

I thought time was successive intervals?
How does that not sum everything up?
Is it because of GR?

I love this topic!

Rade

According to Aristotle, Physica, Book VI, he claims the following about time:

Suppose three moments, A, B, C and a physical thing {T} in motion in "space" in relation to them. From my understanding of Aristotle, the moments are indivisible and have neither motion nor rest, thus they are outside of time, yet they are the limits of past and future time, such that:

In the above diagram consider the relationship of time 2 & 3 to moment |B|. There exists infinite numbers of motions of the thing {T} in space that can be counted in time #2 leading to |B| (the past) and in time #3 leading away from |B| (the future) and these motions that can be counted are "time". Thus, moment |B| is both a limit of past time (time#2) and future time (time #3), and while it can be said that |B| is in this sense, as a limit, a part of time, there is no time within the moment|B|, since time is always divisible while |B|, because it is a moment, is always indivisible. And see that while time #2 is the past of moment |B|yet also is time#2 within the future of moment |A|.

Thus, as the concepts "odd" and "even" are within number, so the concepts "past" and "present" and "future" (moments) are within any time. So, time will never fail to exist if there is motion of a thing in space that exists, for where there is motion, there is always a beginning to time.

Now, Aristotle also holds "space" = "that which is intermediate between existents". Thus, it is possible to suggest that Aristotle would claim that;
Applying the above diagram, suppose two existents {E1} and {E2}, and they are in motion at two different moments |A'| and |B'| in space-time:


So, here we see that "space-time" is that which is intermediate between {E1|A'|} and {E2|B'|} as these two existents relate to the three moments A, B, C and their respective concepts of past and future time.

This is my understanding of what Aristotle may claim about the philosophic question..."what is time" as relates to physical things that exist that follow the laws of nature.

pervect

OK, given that we are now talking about Aristotle, and given the title of the topic, I think it's time (probably past time) that I move this to the philosophy forum.