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Is time linear?

 
 
layman
 
  0  
Reply Sat 21 Feb, 2015 07:03 pm
@argome321,
To be more specific, you asked:

Quote:
So are we asking is time linear in accordance to the physicist definition of time or the time we use to record our time here on Earth?


If you are asking that question, then I think that, using the parameters you gave, time is NOT linear (if "linear" is taken to mean steady and constant). The speed at which the earth revolves around the sun is not constant, from what I understand. Nor, I think, is the rate of daily rotation absolutely the same for each day of the year. Physicists use averages (based on sidereal time, not "solar time") for example:

Quote:
A mean sidereal day is about 23 hours, 56 minutes, 4.0916 seconds (23.9344699 hours or 0.99726958 mean solar days), the time it takes the Earth to make one rotation relative to the vernal equinox...


http://en.wikipedia.org/wiki/Sidereal_time

There are all sorts of different definitions given at that site. A few examples are: (1) Greenwich Mean Sidereal Time (GMST) (2) Local Apparent Sidereal Time (LAST), and (3) Greenwich Apparent Sidereal Time (GAST).

argome321
 
  0  
Reply Sat 21 Feb, 2015 09:00 pm
@layman,
Quote:
If you are asking that question, then I think that, using the parameters you gave, time is NOT linear (if "linear" is taken to mean steady and constant). The speed at which the earth revolves around the sun is not constant, from what I understand. Nor, I think, is the rate of daily rotation absolutely the same for each day of the year. Physicists use averages (based on sidereal time, not "solar time") for example:


I understand sidereal time and the circumference ff the equator etc.

What I mean by linear is literately a line where one action follows another action and on the same plane and another action follow that action usually each contingent upon the prior action on the same line and so forth.

from Dictionary dot com

I was just using these definitions

of, consisting of, or using lines:
linear design.
2.
pertaining to or represented by lines:
linear dimensions.
3.
extended or arranged in a line:
a linear series.
4.
involving measurement in one dimension only; pertaining to length:
linear measure.
5.
of or relating to the characteristics of a work of art in which forms and rhythms are defined chiefly in terms of line.

E.G.
A pitcher throw a fast ball on the outside corner for a strike. The batter either swings, makes contact or misses or keeps the bat on his shoulder. Each ensuing action is a direct result of the prior act as both the pitcher and the batter think about their next move. Every action setting a series of new actions down the line.

So my question is is space time the same as if asking for the time of Day? If not would it not better to give different names to these actions as not confuse the layman?
Or perhaps when it comes to Physic I'm too thick?

Also I came across this


I don't know if it valid or not
http://manage-time.com/linear.html
layman
 
  0  
Reply Sat 21 Feb, 2015 09:28 pm
@argome321,
Quote:
What I mean by linear is...


According to the OP (Neologist):

Quote:
You're right. I didn't think the question through. I suppose I could have asked "is time constant?"


I guess the first thing to decide on is what is intended by the word "linear" in the post title, eh?
layman
 
  0  
Reply Sat 21 Feb, 2015 09:37 pm
@argome321,
Quote:
Also I came across this--I don't know if it valid or not
http://manage-time.com/linear.html


Valid or not, it certainly appears to be quite relevant to the topic at hand. It gives its own definition of linear time, for example.

I haven't read it all, but I see one claim, right at the outset, that I have trouble agreeing with, to wit:

Quote:

Linear time is a major feature of our Western cultural world-view, apparently initiated by Newton some 300 years ago. It portrays time as an absolute physical reality, and says that the passage of time is independent of consciousness


I can't agree that Newton thought time was a PHYSICAL reality. It was a conceptual thing for him. He did, however posit "absolute" time as a concept. That is presumably why the author here is calling it " absolute physical reality.".

Either way, I don't agree that Newton thought it was a "physical" reality (nor do I).
neologist
 
  2  
Reply Sat 21 Feb, 2015 10:14 pm
@layman,
I started the OP from the point of view of the naive realist.

Hope that helps.
layman
 
  0  
Reply Sat 21 Feb, 2015 10:23 pm
@layman,
Newton on the concept of "true" (absolute) time:

Quote:
“Although time, space, place and motion are very familiar to everyone, it must be noted that these quantities are popularly conceived solely with reference to the objects of sense perception. And this is the source of certain preconceptions; to eliminate them it is useful to distinguish these quantities into absolute and relative, true and apparent, mathematical and common.

Absolute, true, and mathematical time, in and of itself and of its own nature, without reference to anything external, flows uniformly and by another name is called duration. Relative, apparent, and common time is any sensible and external measure (precise or imprecise) of duration by means of motion; such a measure – for example, an hour, a day, a month, a year – is commonly used instead of true time...

In astronomy, absolute time is distinguished from relative time by the equation of common time. For natural days, which are commonly considered equal for the purpose of measuring time, are actually unequal. Astronomers correct this inequality in order to measure celestial motions on the basis of a truer time. It is possible that there is no uniform motion by which time may have an exact measure. All motions can be accelerated and retarded, but the flow of absolute time cannot be changed.”


http://www.relativity.li/en/epstein2/read/a0_en/a1_en/

Einstein chose to reject Newton's concept of time, but that was merely a choice. He did not, nor has anyone ever, empirically demonstrated that Newton's concept of time is not "true." The author here elaborates on the implications of Newton's time, as follows:

Quote:
This true and absolute time implies that the simultaneity of two events is an absolute fact. It is independent of the location or of the state of movement of the observers. Time flows the same for all, just as the sun shines the same on all, just and unjust alike.


Einstein invented the concept of "relative simultaneity." But a theory of relative motion which incorporates Newton's concept of "absolute simultaneity" makes all the same predictions, just as accurately, as does Einstein's special relativity. Empirical experiment cannot distinguish between the two.
layman
 
  0  
Reply Sat 21 Feb, 2015 11:04 pm
@layman,
Quote:
It is possible that there is no uniform motion by which time may have an exact measure. All motions can be accelerated and retarded, but the flow of absolute time cannot be changed.”


Here Newton clearly distinguishes our ability to measure time from the concept of time itself. The two are not the same. For Newton, an inability to measure "true time" does not invalidate the concept.

Newton would obviously reject Einstein's positivistic definition that "time is what a clock measures."
0 Replies
 
layman
 
  0  
Reply Sat 21 Feb, 2015 11:08 pm
@neologist,
Quote:
I started the OP from the point of view of the naive realist.


How does a "naïve" realist differ from a "sophisticated" realist, if at all, Neo?
neologist
 
  1  
Reply Sat 21 Feb, 2015 11:23 pm
@layman,
Oh great! Now I have to do another Google search!
0 Replies
 
layman
 
  0  
Reply Sun 22 Feb, 2015 01:07 am
@neologist,
I am supposing, Neo, that the spirit of your question related to the concept of time, not with our method of measuring it, per se. Put another way, your question seems to be one about the nature of time, not the mechanics of clocks.

Inferring evaluative conclusions from purely factual premises is a process that has been called "the naturalistic fallacy." It seems to me that this fallacy is committed when someone argues, for example, that because clocks slow down with speed, that means time cannot be "absolute" (in Newton's sense of time which "flows uniformly"). This simply binds the meaning of time to the mechanics of clocks. I don't see how the fact that clocks change rates with speed can, in itself, alter the concept of time.

The fact that a clock can "slow down" does not mean that "time itself" slows down. The fact that you haven't recently wound your wristwatch (causing it to "run slow') alters nothing about the "real time." At that point, the time is simply NOT what your watch tells you it is. If it's now an hour slow, and reads 3:00, it still 4:00.
Quehoniaomath
 
  0  
Reply Sun 22 Feb, 2015 03:17 am
@layman,
nobody even knows what time is.
0 Replies
 
FBM
 
  1  
Reply Sun 22 Feb, 2015 04:02 am
If you're a photon, you don't experience time at all unless you're going through a medium that slows you down. Then it's still not a buttload of time. So for all those photons that have been speeding around unimpeded since the Big Bang, nothing has happened at all in these (for us) 13.7 billion years (slightly less, since photons weren't free to propagate for a whopping 10 seconds after the BB, after the lepton epoch).

Also, space-time is warped by gravity, so even if it's linear to us non-photons, it's not rectilinear, but curvilinear. The SR angle has already been brought up, so I'll skip that.

Feynman diagrams work equally well with both arrows of time, if I recall correctly.

Subjectively, though, it's a different matter. Both of my appointments cancelled today and I have nothing particularly interesting to do until Tuesday night, when clear skies are forecast and I can take my telescope/camera out. Time has all but come to a standstill for me.
0 Replies
 
FBM
 
  1  
Reply Sun 22 Feb, 2015 05:20 am
Quehoniaomath
 
  0  
Reply Sun 22 Feb, 2015 05:28 am
@FBM,
you are sure it are no lies, mate?!
0 Replies
 
dalehileman
 
  0  
Reply Sat 19 Dec, 2015 11:49 am
@Wilso,
Quote:
Apparently, the faster you move, the slower time runs for you
But Wilso it's a relative thing. Though you don't sense any change in yourself, everyone around you sees your clock as slowing. At c, stopped

Quote:
I wish someone could explain that in language I can understand
I'd be glad to elaborate Wil if you desire. However I should add that there's a lingering problem with clock slowing, called the Twin Paradox:

To be sure, during your trip to visit Marty you see my clock as stopped just as I see yours, and and after you finally brake of course I see you at the same age as when you left. However, looking back it's apparent to you that the instant you stopped, my clock must have instantaneously jumped ahead 5 minutes

Some "experts" blame my deceleration for the diff tho others insist that my world (and universe) are closer to that elusive stationary ref than you were during your trip. All "proofs" to the contrary, I get the distinct feeling they really don't know
cicerone imposter
 
  1  
Reply Sat 19 Dec, 2015 12:30 pm
@dalehileman,
We all heard of lunar year, and the number of days in February changes to show the change in our earth's rotation. I believe the most accurate timing of earth's rotation is the atomic clock.
layman
 
  0  
Reply Sat 19 Dec, 2015 12:56 pm
@cicerone imposter,
Quote:
We all heard of lunar year, and the number of days in February changes to show the change in our earth's rotation.


It doesn't take 365 days for the earth to complete one full revolution around the sun. It takes 365 1/4 days. Hence an additional day every 4 years, so that the calendars don't get plumb wack over time.
0 Replies
 
dalehileman
 
  1  
Reply Sat 19 Dec, 2015 01:57 pm
@cicerone imposter,
Quote:
... lunar year, ...February changes.... in our earth's rotation....... most accurate timing.... is the atomic clock
Cis you may have misunderstood my last posting. I was responding to Wil's q about relative time, asking about the apparent slowing of a moving clock, which I understand has been demonstrated repeatedly by atomic means
cicerone imposter
 
  1  
Reply Sat 19 Dec, 2015 02:07 pm
@dalehileman,
There are many examples of how we experience apparent slowing of a moving clock. When we're waiting in line at a store to check out......time slows to a crawl. When we keep looking at our watch, it's an indication of the "slowness of time."
0 Replies
 
selectmytutor
 
  0  
Reply Sat 16 Apr, 2016 03:48 am
@neologist,
I think yes time is linear.
0 Replies
 
 

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