|WHAT IS TIME? WHAT CAUSES TIME?
Writer and physicist Paul Davies has called "time" Einstein’s unfinished revolution. There are many questions about the nature of time. What
is time? What causes time? Why time slows in gravity? Why time slows in motion? Is time a dimension? Aristotle had speculated that time
may be motion. He however added that motion could be slower or faster but not time. Aristotle did not have the privilege of knowing about
Einstein’s relativity in which time also becomes amenable to change. Similarly when Einstein was working to develop theory of general
relativity and proposed the revolutionary idea that mass curves space he did not know that the universe was expanding. This discovery by
astronomer Edwin Hubble came 13 years after Einstein had published his theory of General Relativity. Had Einstein known of this great
discovery he may have incorporated these ideas into his theories. Conceptually it is easier to derive space curvature in an expanding
universe as an area of slower expansion under the influence of gravitons. One of the most dramatic aspects of the universe is that it is
expanding and the presence of motion, forces and curved space-time happens in the expanding space.
In the next few paragraphs I will show that time is an emergent concept. There is an underlaying process of motion and forces from which
time emerges, however what we perceive as time is mostly an illusion. Our memory creates the illusion of the past. Conscious perception of
events gives the feeling of present. Future is a mental construct patterned on the memory experience of the past. Concept of time emerges
as our mind tries to make sense of the world around us which is filled with change.
Mc TAGGART ON THE ILLUSION OF TIME
John Ellis McTaggart (1908) and many other philosophers have proposed that the passage of time is an illusion suggesting that only the
present is real. McTaggart is famous for his A, B and C series analysis of time. A brief review is as follows:
The earlier and later aspect of time is basically the same as the arrow of time. The birth of a person always comes before their death even as
these events become part of the distant past. This is a fixed relationship so McTaggart asserts it must be more fundamental to time.
The past the present and the future aspect of time is constantly changing, future events are moving to the present and then into the past and
then further back into the past. This aspect deals with the feeling of flow of time. This constantly changing relationship is also essential to the
description of time. McTaggart felt that time is unreal because distinction of past present and future (a changing relationship) is more
essential to time then the fixed relationship of earlier and later.
TIME AS MEMORY
McTaggart's most interesting observation however is that historical events have same time characteristic as made up stories. For
example made up stories, as well as past historical events have in them, the earlier and the later as well as the past the present and the
future, thus suggesting that past really is more like memory of events and does not exist any more than imagination of a writer. The above
point becomes more clear when we compare past present and future to other recording devices like laser discs CDs and hard drives.
|More powerful than all the armies of the
world, is an idea whose time has come.
PRESENT IS AN INFINITESIMAL?
Present is the most real perception of time however almost all of what we perceive as
the present is already past. The present is a fleeting moment, whatever is
happening now (present) is confined to an infinitesimally narrow point on the time
line which is being encroached upon by what we think of as the past and the future.
Present resembles the sharp point of a recording laser or needle while past
being a duration or extension resembles the recorded material like tape or CD.
Present may be mental awareness of the recording of memory into our brain. A
person can go to an event but fall asleep and miss the event completely. So that
event basically does not exist in his past. Unless we are consciously aware of an
event it does not seem to enter our past memory.
PAST AND FUTURE ARE DURATIONS IN TIME
Unlike the present we see past and future as measurable
durations of hour days months and years.
Past historical events, an upcoming meeting, wedding, or other
events are all measurable durations or extensions in time, just
like a recorded material on tape, video recordings, and tracks of
CD or DVD.
This similarity suggests that past is just a recorded memory,
while future is like an unrecorded tape. Future is a projection
created by our past experiences which are stored in our memory.
Be it money, weight, a piece of estate, speed, distance or resistance. We measure by comparison to a standard that we have defined. When
we measure a mass we use a standard mass like KG or LB for comparison. Distances we measure using a standard of length like a meter
yard or feet. Keeping the above in mind let us think how we measure motion. We use time to measure motion i.e. Feet per second or miles
per hour. This provides a hint that when dealing with time we are actually dealing with some standard of motion.
We may have made the concept of time more complicated then what it really is. Measurement of time started early on in human
development. There are plenty of clues in every language in the greetings and the meetings. Time of the day is related to the position of sun
in the sky or its absence thereof. There is dawn, sunrise, early morning, morning, mid morning, noon, afternoon, late afternoon, evening,
sunset, dusk, night and mid night. Then there are years, months, weeks, based on earth’s yearly orbit around the sun and the changing
seasons. The use of units like seconds and minutes which are radial angle measurements in geometry points toward the original
connection of time measurements to radial motion of astronomical objects across the sky. Once we started using clocks, watches, and then
digital time we got completely disconnected from the original method of measurement and time developed a life of its own.
The problem of time may be easy to solve if we go back to the original concept of sun moving across the sky. When we measure the speed of
a car, we are just comparing its motion to the motion of the hands of the clock and also indirectly to the fractional motion of sun across the sky.
We are not measuring speed with something abstract called time we are just comparing a known motion (of the sun) with an unknown motion
of the car.
TIME AS UNIT OF MOTION
In a recent article in Scientific American Craig Callender elegantly compares time with a unit of motion. Time is a way to compare or describe
different kinds of motions like speed of light, how fast heart beats or how frequently earth spins around its axis. But these processes could be
compared directly without making reference to time. Time may just be common currency or unit of motion making the world easier to
describe but having no independent existence. Measuring processes (of motion) with time is like using money rather than barter transactions.
This again suggests that underlying mechanism of time is just presence of motion.
WHAT REALLY IS TIME?
Time is an emergent concept. There is a real phenomenon a continuous change through which we live. To understand time we have to
understand the mechanism which brings about this continuous change from which our mind creates the illusion of flow of time.
Time becomes evident through motion and is measured by comparison with other motions. Sunrise sunsets, night and day, the changing
seasons, the movement of the celestial bodies are all indicative of continuous change. The aging process is a reminder that molecular
motion and interactions are also at work and are a part of time. Other very important aspect of time is presence of motion of particles like
photon and motion at atomic level.
A THOUGHT EXPERIMENT
Imagine two objects one moving in orbit around the other in space. Now suppose from
our distant observation point of a fixed time we observe time to get slower in the area
where these two objects are moving. We expect to see slower motion? We also should
observe proportionally weaker gravitational force; otherwise the objects will get pulled
together. If we observed faster time, we expect to see faster motion and stronger gravity to
keep the objects from flying apart. While with zero time motion will freeze and gravity will
The increase or decrease in strength of gravity is only in relation to our fixed time from
where we are making the observation. From the point of view (time) of the orbiting objects
neither motion nor gravity has changed. As this thought experiment also can be
extended to particles held together by electromagnetic forces we can say that time
involves both motion and forces.
POSSIBLE DEFINITION OF TIME
Time can be defined from many perspectives. From perception view point time is
an emergent concept which our mind creates. Present is the consciousness or
awareness of recording of memory into the brain. Past is just a record while future
does not exist. From point of view of physics time is presence of motion and forces
in the universe.
Time involves all kinds of motion. The spin of particles and the motion of photons are
time dependent. Gravitational force and electromagnetic forces are all part of time. As is
the motion of celestial bodies the atoms and all other motion. We have partially
understood the phenomenon of time. The next step is to find out what is the source of
this motion and forces.
|Rotating buckets and twin
paradox reveal the
significance of motion
|Moving objects also curve space