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What is time?

Feel free to delete this if not appropriate.

Is anyone else fascinated by time?  What it is and how we measure it?

Time is really just the passage of events that cannot reverse themselves?  If I drop my pencil I can't go back in time and pick it up again but I can just pick it up which creates another event.  So now I have a memory of dropping my pencil and picking it up again.  A sequence of events that define time.

How do you gals/guys define or understand time?

Anon
Thursday, June 03, 2004

That which I never have too much of.

RP
Thursday, June 03, 2004

Read up a bit on Einstein's theories of the relationship of space, time, and gravity. Somehow they're all connected, but I don't claim to understand how...

Tom H
Thursday, June 03, 2004

I see time as just another dimension of existence, with some unusual quirks in how it interacts with the spacial dimensions (i.e. relativity).  We only observe time in one direction, but that's a limitation of us and not of time itself.

It's kind of like the words in a book... the words (taken as a whole) are static, and they all exist at once.  But they're meaningless unless you read them in a sequence, travelling in exactly one direction.

Interestingly (speaking of books), I just finished reading Grant Naylor's "Better Than Life", a novel from the Red Dwarf universe, and one of the interesting propositions (used to humorous effect) is that our universe seems so absurd because we're traversing time in the wrong direction.  The implication is that if cause and effect were reversed, it would all start to make some sense.

Pierce
Thursday, June 03, 2004

    There is no 'time'. There is only space-time. Space-time is a field, like say, a magnetic field - which itself exists within space-time.

    This field is the area within which any and all physical phenomena occurs. Even our thoughts need space-time. Our heads are a physical construct.

    Discrete vs Continous time is not resolved and IMVHO no resolvable. Easy to accept to work with the assumption that it is continous for dynamic systems and discrete for abstract static conceptions.

    For more information, read up on General Relativity as mentioned earlier.

.
Thursday, June 03, 2004

Would time exist without intelligent beings to measure it?

John Topley (www.johntopley.com)
Thursday, June 03, 2004

Yes.

.
Thursday, June 03, 2004

So did time have a beginning or has there been an infinite amount of time that has passed up until this point?  If it had a beginning then what happened before that?  It there has been an infinite amount of time then...well I just don't get it.

timeless
Thursday, June 03, 2004

No.

Definitely
Thursday, June 03, 2004

I know a cat that may disagree.

_
Thursday, June 03, 2004

Doesn't it work like a Game Engine or a message-driven GUI application?

It's a counter that increments, you can save or check the value of that counter on certain instant (that's what we call a clock). While the counter increments, certain actions are performed in response to others. Since its a one-way counter, you cannot decrement it and somehow undo an action. You can however undo the action, while the counter is still incrementing. But it still depends, how cleanly it can be undone.

Green Pajamas
Thursday, June 03, 2004

    Having accepted that Time has a begining, asking what happened before it is nonsensical. Where were you before you were born? 'Before' has no meaning outside time.

    Big Bang. The start-off point. Before and Where have no meaning. It is a start-off point. That is all.

    For a fun take on time read DNA's Hitchihiker series. It makes actual some sense as well.

.
Thursday, June 03, 2004

    As to the famed feline - it is _NOT_ the case that the she is _both_ dead and alive at the same time, or she is both dead and alive at two different planes of time.

  The Uncertainity theory limits _ our knowledge_ of the state of the cat. _Not_ the state of the cat.

.
Thursday, June 03, 2004

Time does not increment, it does not change, it persists in the same way that length or breadth persists.

Simon Lucy
Thursday, June 03, 2004

1 An asymmetric dimension of space-time with the asymmetry defined by increasing disorder/entropy.

2 A dimension of space-time which requires the use of imaginary numbers to play nice with the other 3.

3. Limited.

a cynic writes...
Thursday, June 03, 2004

., I think you've missed the point of the thought experiment. Of course, at the macro level, the cat's state is simply unknown, as you've pointed out. However, the point of the thought experiment is to illustrate the concept of quantum superposition - it has to be understood that it really only exists at a quantum (micro) level, (eg the double-slit experiment).

Schrodinger simply used the cat as an analogy (and regretted it afterwards)

Chris
Thursday, June 03, 2004

And that is my point. Analogies go only thus far. What was intended to be an experiment, albeit abstract, to show how at the quantum level complete and accurate predictions are impossible and therefore all constrcuted systems inherit this inherent uncertainities, has morphed into a blanket statement that goes on to say that the whole of existence does not exist as well.

Much as I disagree with both Plato & Aristotle, 'A is A' and 'A cannot be not A'.

.
Thursday, June 03, 2004

The computer analogy might be a good one.

Here's one way to think about it all in a discrete computational way (assume space, time, and matter are all discrete):

A spatial cell: [ ]
A spatial cell linked with another: [ ]--[ ]
A spatial cell filled with a quantum of matter 'x': [x]
The movement of 'x' from one time step to the next (ie: the speed of light): [x]--[ ] -> [ ]--[x]
A biased path (ie: gravity, or force in general):
      [m]                    [ ]
        |                      |
[ ]--[ ]--[ ]  -> [ ]--[m]--[ ]
        |                      |
      [ ]                    [ ]


Thursday, June 03, 2004

This page has many of the answers you are seeking:

http://whattimeisit.com/

Dennis Atkins
Thursday, June 03, 2004

You may find this thread on Slashdot interesting:

http://books.slashdot.org/comments.pl?sid=101479&threshold=-1&commentsort=0&tid=134&mode=nested&cid=8649893

Akilesh Ayyar
Thursday, June 03, 2004

Also get yourself a copy of 'About Time' by Paul Davis and have you read Stephen Hawking's pop-science masterpiece?

.
Thursday, June 03, 2004

From a practical point of view, I find clocks and horology far more interesting than time as a theoretical concept.

Andy in Austin
Thursday, June 03, 2004

There is a book called "Deep Simplicity: Chaos, Complexity and the Emergence of Life" by John Gribbin which talks about this stuff, especially thermodynamic time and the relation to entropy, etc:

http://www.amazon.co.uk/exec/obidos/ASIN/0713996102/qid%3D1086279651/026-1183871-2239649

I think it is an excellent book, covering a wide range of topics, and would recommend it to anyone who is interested in this stuff.

In particular, it gives a failry convincing argument for the emergence of life being inevitable.

Steve Jones (UK)
Thursday, June 03, 2004

An educated opinion @
http://www.edge.org/3rd_culture/smolin/smolin_p1.html
or
http://www.fortunecity.com/emachines/e11/86/whattime.html

There is also an article available in Scientific American (for 5$) by the same author
Atoms of Space and Time

Dino
Thursday, June 03, 2004

All I can contribute is this proverb:

Time flies like an arrow; fruit flies like a banana.

John C.
Thursday, June 03, 2004

Saint Augustine wrote:

"What then is time?  If no one asks me, I know what it is.  If I wish to explain it to him who asks, I do not know."

There was a NOVA episode on PBS back in the early 80's (I think) called "It's About Time", hosted by Dudley Moore. It contained information about relativity, time travel, quantum time, etc. Highly recommended (if you can find it).

Keith Moore
Thursday, June 03, 2004

I can't define time, but I know when it's being wasted.

Michael Eisenberg
Thursday, June 03, 2004

"The Uncertainity theory limits _ our knowledge_ of the state of the cat. _Not_ the state of the cat. "

One of the more interesting and "strange" things that I learned in my year of Quantum Mechanics in college is that actually, the reverse of that statement is true.  While the analogy is often given that it is our knowledge that is uncertain, because it is easier to comprehend, quantum theory actualy says that it is the state of the (electron, quark, maybe even cat, etc.) that is indeterminate.

So the real question is, what collapses the wave function?  And is there an alternate timeline (weak tie back to OP) which has the opposite result happening?

madking
Thursday, June 03, 2004

IIRC Castaneda alluded that you see distance and hear time. So if you want to observe it, keeping your ears open might help.

Tayssir John Gabbour
Thursday, June 03, 2004

IANAP nor a physics student, but Madking,

"...quantum theory actualy says that it is the state of the (electron, quark, maybe even cat, etc.) that is indeterminate."  is not what I understood it as.

I understood it as "....particle with a definitely measured momentum for which there must be a fundamental *_limit to how precisely its location can be specified*_", emphases mine. So, since it is our specification of the state or our observation of it that  is indeterminate for its entirity, how does that lead to the actual state itself being indeterminate?

Or is their a mathematical equivalent of "my perceptions are my truths"?

.
Thursday, June 03, 2004

The "Better Than Life" reference is similar to the book "Slaughterhouse-5" by Kurt Voneegut Jr. He covers the topic of being disconnected in time and the idea that if time for us flowed backwards it would be much more enjoyable.

Coming to life after being dead, then being old and wise and knowledgeable then growing younger and younger and at the end being a baby and being taken care of for your last days, etc.

Kurt does good work
Thursday, June 03, 2004

Someone used to have "The time you enjoy wasting is not wasted time" as their e-mail sig, but I can't attribute the quote. Hey, have Google invented a quote engine yet?

John Topley (www.johntopley.com)
Thursday, June 03, 2004

Time is an illusion, lunch time doubly so.

GML
Thursday, June 03, 2004

John Topley: I believe the source is Bertrand Russell.

Google may not have invented a quote engine, but there's always http://www.bartleby.com/quotations/ (though a quick peek there didn't locate this particular one).

John C.
Thursday, June 03, 2004

Time is money.  Ask any lawyer.

Steve Barbour
Thursday, June 03, 2004

I'm surprised nobody's said "Time was invented to prevent everything from happening at once."

Time is just ticks on the clock.  I have no use for time, except as an intermediate value to measure speed.  It's a word that means "what does the dial on the wall read".  I'm not very good at controlling its speed yet, so that's all it is to me.

For you philosophical time freaks: is time discrete?

Wally
Thursday, June 03, 2004

How about this?

Is time quantisable? Are there an infinite bits of time between one moment and the next, or does time tick by in a digital fashion? The second hand appears to sweep in an analog fashion, but if you look close enough you'll see little steps. Is time the same; little steps on a very small scale?

gwyn
Thursday, June 03, 2004

I believe Brian Greene's books talk about some of the latest speculations from string theory and quantum gravity theorists about whether time (and space) is quantized or not. As far as I know nobody has yet figured out how to find a definitive answer to this one.

John C.
Thursday, June 03, 2004

special relativity == "my perceptions are my truths"


Thursday, June 03, 2004

2 points to GML for the HHGG reference.

Time is not quanitizable (I think) and for some reason that's of particular significance to people who care about such things.

www.MarkTAW.com
Thursday, June 03, 2004

Yes, check out Brian Greene's latest book.  Very similar to his last book.

http://www.amazon.com/exec/obidos/ASIN/0739309250/

It is uncertain whether my cat will purr or bite when I pet him. Yet I'm still a cat person.

No matter where/when you are...it's always beer time.

do fuss
Thursday, June 03, 2004

"Time is not quanitizable [...]"

To my computer it is, and that's all the matters to me...

Wally
Thursday, June 03, 2004

Dimly remembered (from the late 80s) I think you'll find that the quantum of time is the period taken for a particle to change in energy level.  I'm not sure how you'd measure it.

a cynic writes...
Friday, June 04, 2004

._, to address your comment about whether the state was indeterminate or just our knowledge of it, look up the EPR Paradox.  It was a thought experiment derived by E, P, and R  (Einstein, Pedowski, Rosen  (I can't spell, so take the spelling with a grain of salt and I may even have the names wrong), that could be used to determine that question.  Apparently in the 80's technology had advanced to the point where they could actually run the experiment.  Result, quantum theory: 1, common sense: 0.

madking
Friday, June 04, 2004

Heard of it. Perhaps even would have read it. Will read up on it. Thanks.

.
Friday, June 04, 2004

Time has come today
Young hearts can go their way
Can't put it off another day
I don't care what others say
They say we don't listen anyway
Time has come today

The rules have changed today
I have no place to stay
I'm thinking about the subway
My love has flown away 
My tears have come and gone
Oh my Lord, I have to roam
I have no home
I have no home

Now the time has come
There's no place to run
I might get burned up by the sun
But I had my fun
I've been loved and put aside
I've been crushed by the tumbling tide
And my soul has been psychedelicized

Now the time has come
There are things to realize
Time has come today
Time has come today

Chambers Brothers
Friday, June 04, 2004

Do something for a while.
Pause
Reverse
While a for something do.
Pause
Reverse
Do something for a while.

Jared Katze
Tuesday, June 08, 2004

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