Archive for the ‘Time’ Category

Increasing specks of jelly in the peanut butter shows the arrow of time

August 19, 2007

Suppose you watch two time-lapse video clips. In the first video clip you see progressively more and more specks of jelly in the peanut butter. In the second clip you see less and less specks of jelly in the peanut butter.

Which video clip shows forward direction of time? Which shows time in reverse?

Answer: the first video clip shows forward direction of time.

Initially the jelly and peanut butter were separate, i.e. “ordered”. Over time, as the children make peanut butter and jelly sandwiches more and more specks of jelly get into the peanut butter and there is a greater degree of mixing of the two, i.e. it becomes more “disordered”.

There is a general trend in our world toward increasing disorder, e.g. cars rust, buildings crumble, mountains erode, apples rot, and cream poured into coffee dissipates until it is evenly mixed.

In fact, scientists have created a “law” that states that the disorder of the whole universe is increasing. Over time, all order, structure, and pattern in the universe breaks down, decays and dissipates – the ultimate end point of the universe is a random, featureless, homogenized murkiness. It is this increasing disorder that gives time its arrow, e.g. it is the increasing disorder of the peanut butter which enabled you to know which video clip shows the forward direction of time.

Scientists call this disorder “entropy”, and the law which states that the universe becomes increasingly disordered is called The Second Law of Thermodynamics.

— Extracted from The Origin of Wealth by Eric D. Beinhocker

Is Time Finite or Infinite? Time Before the Big Bang?

July 23, 2007

An examination of the most carefully written scientific treatments of the astronomical evidence, and of the cosmological theory which appears to fit the evidence, will discover that the big bang theory does not posit an absolute beginning of the cosmos — a coming into existence out of nothing — but only an initial event in the development of the cosmos as we now know it, an event that occurred at a time that is estimated as between fifteen and twenty billion years ago.

Our present techniques of observation and measurement, and the technical facilities they employ, do not permit us to penetrate the past beyond the time, some fifteen to twenty billion years ago, when the big bang occurred.

What is being said here is not that past time is limited (finite rather than infinite), but only that our knowledge of past time is limited — limited to a time beyond which our observations and measurements cannot go. Time may extend back infinitely beyond that initial explosion of matter, out of which the present shape of the cosmos has developed, but unless some radical alteration in our techniques and instruments of observation and measurements occurs, we will never be able to penetrate the veil that hides the infinite past from us.

— Mortimer J. Adler

Measuring Time

July 22, 2007

Time is defined by reference to astronomical phenomena. Astronomical recurrences mark out equal intervals of time:

– a year is defined as one trip of the earth around the sun

– a day is defined as one rotation of the earth

Relegation of the determination of the measure of time to the astronomer arises from the consistency[1] of the recurrences with which they deal. If such consistency had been noted among the recurrences characteristic of the human body, we would have looked to the doctors of medicine to determine the measure of time[2].

[1] Example of a “consistent” recurrence: the number of days it takes for the earth to orbit the sun is 365.25 days, year after year … the recurrences are consistent. For all ordinary purposes of life on earth, the various astronomical recurrences may be looked on as absolutely consistent.

[2] The heart beat is periodic, but not consistent; it beats quickly when we are active, slower when we are resting; such inconsistent recurrences would not be useful for measuring time.

— Alfred North Whitehead, An Introduction to Mathematics

Question: how is “hour” measured? Is there an astronomical recurrence that indicates an hour? An hour is one twenty-fourth of a day, of course, but how did the ancients realize that one twenty-fourth of a day has elapsed?

Imagine a World without Periodicity

July 15, 2007

Definition: an event is periodic if there are successive events so analogous to each other that they may be termed recurrences of the same event.

Imagine a world in which there are no periodic events.

There would be no concept of a day or a month or a year.

The whole conception of experience as a guide to conduct would be absent.

There would be no heartbeat, no breathe.

There would be no seasons, no tides, no phases of the moon.

We may be able to identify sequences of events, e.g. A occurred before B which occurred before C, but we would not be able to measure the time between events because time is intimately dependent on periodicity.

Periodicity is fundamental to our conception of life.

We cannot imagine a course of nature in which, as events progresses, we should be unable to say: “This has happened before.”

— The above is extracted from a book by Alfred Whitehead North

P.S. There is a book called Flatlander, which describes a world in which there is no third dimension.  It would be fascinating, I think, to write a book which describes a world in which there is no periodicity.  What would be the title of such a book?