Time standards

[Mitch Cronin]

This is cool: http://www.usno.navy.mil/USNO/astronomical-applications/astronomical-information-center/universal-time

...I didn't realize "leap seconds" were added so frequently... Nor had I ever heard of "UT1"...

[Moon The Loon]

Mitch, the measurement of time has been a fascination of mine ever since I read David Ewing Duncan's book "Calendar". We use leap seconds now more and more to adjust our calendar so that each few years, we are in the exact same spot in our orbit around the sun as we were previously - within meters. Either a year ago, or 50 years ago. It's easier now, especially with the new clocks designed for the GNSS systems which had to be more accurate than the previous cesium clock standard due to the relativistic distances between the satellites (they're in a 22,000 mile high orbit! +/- of course) as well as our powers of observation.

Now, when you think about the Mayan calendar, developed over 2,000 years ago with a period of over 5,000 years, and more accurate than the Spaniard's Julian calendar of the 16th eentury, this really puts into perspective the power of the ancient mind. And by the way, the end date for the current Mayan cycle is not 12 December 2012, it's 23 December 2012. According to Duncan.

[Don Hudson]

Hi Moon;

But is the mere measurement of time, time? What is time?

Is time a series of fixed events having a fixed set of properties, which events have a place (a slot) in a static continuum where events occur earlier and later than others but none of them moving around (because they are "things"?

Or is time a past, a present and a future, with events of the future "moving towards" us and events of the past receding away from us and the present events of the present having some sense of immediacy "right there in front of us"?

There are variations on these metaphysical notions which have been widely studied, with little in the way of determining what time really is. In fact, one guy uses both notions to come to the conclusion that "time" doesn't exist and that we are fooled into thinking there is a "pageantry of events" rolling past us because we have both anticipatory powers and memories, neither of which our DNA possesses!

So much for a Sunday afternoon's peace...

[Moon The Loon]

Oh boy, Don, Game ON! The measurement of time is a human-made pass-time in our incessant human need to collect and measure things. In its raw-est (izzat a word??) state, it's what science is. What is, is. There is no future. There is a memory of the past. That memory depends upon individuals, and who might have recorded that memory. What is, gets measured. What was recorded, gets compared with other recordings. What is remembered against what was recorded becomes mystery, or even conspiracy.

Me, I've maintained for decades that Time is not a thing. Time is a concept, conceived by humans. As such, any talk of time travel is ridiculous. Having said that, my favourite science fiction involves time travel - H.G.Wells, Stephen Baxter, etc. (I'm weak, and I accept that... )

Go figure.

[GDR]

Time is one of the most fascinating topics around. Essentially it is how we experience chang, as has been pointed out. Julian Barbour has spent a life time studying time and has some very novel ideas.

Here is a quote from his website.

Closely related to this work is my study of time. Mach remarked “It is utterly beyond our power to measure the changes of things by time. Quite the contrary, time is an abstraction at which we arrive through the changes of things.” Thus, time as such does not exist but only change. Much of my research has been devoted to the implications of this insight. I have shown how, alongside the relativity of motion, the notion of time as change can be built into the foundations of dynamics. In fact, this idea is contained in a hidden form within general relativity. Its potential consequences for the yet to be found quantum mechanics of the universe are profound. The quantum universe is likely to be static. Motion and the apparent passage of time may be nothing but very well founded illusions. This is the thesis of The End of Time (books), which is aimed both at the general reader and physicists.

Here is his web site

http://www.platonia.com/ideas.html

And here is an interview on you tube.

It's great stuff

Greg

[Moon The Loon]

(I knew this would draw Greg out of the woods!)

[J.O.]

Oooh, my head is starting to hurt and this thread isn't even going yet! My favourtie thoughts on time (no surprise ).

Ticking away the moments that make up a dull day

You fritter and waste the hours in an offhand way

Kicking around on a piece of ground in your home town

Waiting for someone or something to show you the way

Tired of lying in the sunshine, staying home to watch the rain

You are young and life is long and there is time to kill today

And then one day you find, ten years have got behind you

No one told you when to run, you missed the starting gun

And you run and you run to catch up with the sun, but it's sinking

And racing around to come up behind you again

The sun is the same in a relative way, but you're older

Shorter of breath and one day closer to death

Every year is getting shorter, never seem to find the time

Plans that either come to nought,

or half a page of scribbled lines

Hanging on in quiet desperation is the English way

The time is gone the song is over,

Thought I'd something more to say

by Roger Waters

[Kip Powick]

[GDR]

(I knew this would draw Greg out of the woods!)

Sorry - can't resist

Here is a simpler approach from the internet

Time, as we know it, is only an illusion. We usually think of time as having three parts - Past, Present, Future. But what is the Past - only a collection of memories. We can't experience the Past, we can only remember it. And we can only remember it in the Present (furthermore, our memories are noticeably unreliable). There is no objective thing that we call the Past; it can't be measured in any way; our only contact with it is in the Present.

And what is the Future - only a mental construct in the Present. We can't experience the Future until it "becomes" the Present. Until then it only a hope and dream. We can project what the Future may be like, but we are considerably less accurate than when we remember the Past. There is no objective thing that we call the Future; it can't be measured in any way; our only contact with it is in the Present.

That leaves us with only the Present - the ever changing Present. Time is an illusion we created to try and measure the rate of change of the Present. It's always NOW. But it's an ever changing NOW. In a effort to cope with the change, we have invented time. It's a handy mental device that helps us deal with the higher order derivatives of the rate of change.

This change that we experience in the ever present Present does have a "direction." Things change in the general direction of having greater entropy. Entropy is a measure of the amount of disorder in a system. That's why when we measure time we find it restricted to one direction (unlike when we measure distance) - things are changing such that the overall system has more and more entropy.

Although the illusionary nature of time is the deep truth in this matter, it's not particularly practical. To be totally in harmony with this truth, you'd need to wear a watch that always said "now". But you'd be late for a lot of meetings....

[Don Hudson]

Greg, Moon;

In fact there is a metaphysical argument by a Scot named McTaggart who, (after naming the tense-less, "earlier/later than theory, the 'B'-theory, and the tensed, "past, present, future theory" the 'A'-theory), analytically proved that 'time does not exist'. 'Analytically' means using deductive/quantificational logic, inductive reasoning and so on, (um...., you think you're the only ones lost here?) to establish a contradiction between the two theories the outcome of which 'proves' time does not exist. Of course, there is no right or wrong or possibly even 'getting warmer, getting colder'; the key is the discussion, as always.

That we now need something to distinguish past, present and future doesn't mean time exists (but it may mean we exist...sorry, I digress). Why do we privilege the dynamic notions of past, present and future as opposed to thinking that events were earlier or later-than each other on a fixed structure which can't change and neither can the events? If a new car part oxidizes for example, in the second theory it is a different event/thing and not the original part; it is marked off as a separate event which occurred later than when the part was new. Change is difference. For the second theory, change is dynamic and eventness and thingness are similarly dynamic.

J.O., I really liked the poem and despite the references to logic, prefer the Existentialist's views. It seems to me that when all the analyzing and logical arguing is done, even if one might claim to be correct (until the next argument), something is still missing. I think that is where the Existentialists come in.