Atkhenaten (PRO)Einstein elaborated on his definition of time and made it clear that his objective was to
get rid of the concept of Absolute Time. This he did, but we now need to understand exactly what he put in its place. Time is one of the trickiest words in human language, for we
use it in a number of different senses which do not at all refer to the same thing. For example,
we say of a journey that it occurred in time, that it started at a specific time and that it lasted
for a period of time. In fact, we carry around with us, and work within, three significant
concepts of time.
• Passage (Flow): We are conscious of our own past experiences which brought us to
the present and to which we can never return. We know, too, that the present will also
become past and will take us into the future. We express these certainties by saying
that Time passes and will carry all of us along with it. This is sometimes called
Absolute Time.
the present and to which we can never return. We know, too, that the present will also
become past and will take us into the future. We express these certainties by saying
that Time passes and will carry all of us along with it. This is sometimes called
Absolute Time.
• Movement: Time brings change, and change is simply a succession of events. Events
occur in space and in time and it is the sequence of events, one after the other, that
gives us our sense of the passage of time.
occur in space and in time and it is the sequence of events, one after the other, that
gives us our sense of the passage of time.
• Measurement: We compare events in terms of the order in which they follow each
other, and how long each event lasts. This involves comparison, and we compare what
is to be measured with a suitable measuring device, such as a clock.
In contrast, we do not speak about Space in the same way, but use words such as space, place
and length or distance to specify the different senses in our concept of Space. If we did
something similar for Time, we might, with Dingle, use the words eternity, instant and
duration for passage, movement and measurement respectively.
other, and how long each event lasts. This involves comparison, and we compare what
is to be measured with a suitable measuring device, such as a clock.
In contrast, we do not speak about Space in the same way, but use words such as space, place
and length or distance to specify the different senses in our concept of Space. If we did
something similar for Time, we might, with Dingle, use the words eternity, instant and
duration for passage, movement and measurement respectively.
We can now see that
Einstein's definition of time is concerned with Movement (instants) and Measurement
(durations) where durations are intervals between instants. In other words, it provides a
metric which allows us to compare different events. About eternity, or the Absolute Time in
which these events take place, this definition, deliberately, has nothing at all to say. Max
Born, puts it this way: "… absolute time has no physical reality. Time-data have a
significance only relatively to definite systems of reference." In our everyday lives, to measure time we use a uniform and consistent periodic sequence of
change with which we can compare other changes in which we are interested. This provides
us with a standard measuring device (a calibrated clock) which allows us to count the passing
moments as Time marches on. Our units of time – second, minute, hour, day and year etc. –
are relative to the periodic rotation of the earth about its axis and its equally periodic orbit
about the sun. All terrestrial clocks are therefore calibrated to measure, as accurately as
possible, these periodicities. Our unit for space, the metre, is similarly tied to the planet.
Originally defined as one ten-millionth of the distance from the Earth's equator to the North
Pole at sea level, it has been redefined a number of times and since 1983 has been expressed
as the length of the path travelled by light in a vacuum during a time interval of
1⁄299,792,458 of a second.
Einstein's definition of time is concerned with Movement (instants) and Measurement
(durations) where durations are intervals between instants. In other words, it provides a
metric which allows us to compare different events. About eternity, or the Absolute Time in
which these events take place, this definition, deliberately, has nothing at all to say. Max
Born, puts it this way: "… absolute time has no physical reality. Time-data have a
significance only relatively to definite systems of reference." In our everyday lives, to measure time we use a uniform and consistent periodic sequence of
change with which we can compare other changes in which we are interested. This provides
us with a standard measuring device (a calibrated clock) which allows us to count the passing
moments as Time marches on. Our units of time – second, minute, hour, day and year etc. –
are relative to the periodic rotation of the earth about its axis and its equally periodic orbit
about the sun. All terrestrial clocks are therefore calibrated to measure, as accurately as
possible, these periodicities. Our unit for space, the metre, is similarly tied to the planet.
Originally defined as one ten-millionth of the distance from the Earth's equator to the North
Pole at sea level, it has been redefined a number of times and since 1983 has been expressed
as the length of the path travelled by light in a vacuum during a time interval of
1⁄299,792,458 of a second.
Results
Enquiring more closely into Einstein's definition of time, he tells us that: "It is essential to
have time defined by means of stationary clocks in the stationary system, and the time now
defined being appropriate to the stationary system we call it 'the time of the stationary
system." He was even more explicit in his book The Meaning of Relativity (1922 and later
editions) when he said: "It is essential to note that this definition of time relates only to the
inertial system K, since we have used a system of clocks at rest relative to K. The assumption
which was made in the pre-relativity physics of the absolute character of time (i.e. independence of time of the choice of the inertial system) does not follow at all from this
definition." In other words, in Special Relativity, there is no Absolute Time and we must define new units
and devices to measure it in each inertial system. We are not allowed to carry the units of
measurement from one system to another. This then is the resolution of the paradox –the
travelling twin must not use the terrestrial units of time because the periodicities on which
they are based will have different values in his inertial frame. Instead, the terrestrial units
should be corrected using the Lorentz factor in order to provide the units appropriate to the
moving inertial frame. In other words, the correction must be applied, not to the instants and
durations in the moving frame, but to the units that are used to measure them.
We can best illustrate the result by using a standard example of the paradox to calculate the
length of travelling twin's round trip for both the currently accepted approach and the
alternative suggested here.
have time defined by means of stationary clocks in the stationary system, and the time now
defined being appropriate to the stationary system we call it 'the time of the stationary
system." He was even more explicit in his book The Meaning of Relativity (1922 and later
editions) when he said: "It is essential to note that this definition of time relates only to the
inertial system K, since we have used a system of clocks at rest relative to K. The assumption
which was made in the pre-relativity physics of the absolute character of time (i.e. independence of time of the choice of the inertial system) does not follow at all from this
definition." In other words, in Special Relativity, there is no Absolute Time and we must define new units
and devices to measure it in each inertial system. We are not allowed to carry the units of
measurement from one system to another. This then is the resolution of the paradox –the
travelling twin must not use the terrestrial units of time because the periodicities on which
they are based will have different values in his inertial frame. Instead, the terrestrial units
should be corrected using the Lorentz factor in order to provide the units appropriate to the
moving inertial frame. In other words, the correction must be applied, not to the instants and
durations in the moving frame, but to the units that are used to measure them.
We can best illustrate the result by using a standard example of the paradox to calculate the
length of travelling twin's round trip for both the currently accepted approach and the
alternative suggested here.
Consider the case of a twin travelling from Earth to a star system at a distance d = 4 light
years away. He is travelling in a rocket whose velocity, v, is 80 percent of the speed of light
(v = 0.8c).
years away. He is travelling in a rocket whose velocity, v, is 80 percent of the speed of light
(v = 0.8c).
At this relative velocity, his earthbound sibling will see the traveler's return
journey time as t = 2d/v = 10 years.
We must next calculate the time interval experienced by the travelling twin.
journey time as t = 2d/v = 10 years.
We must next calculate the time interval experienced by the travelling twin.
For a velocity of
80% of the speed of light, the Lorentz factor (√1 – v
2
⁄c
2
) has a value of 0.6.
80% of the speed of light, the Lorentz factor (√1 – v
2
⁄c
2
) has a value of 0.6.
The standard calculation of the traveler's total flight time is then made as follows:
In this twin's rest frame, the distance to the star system dr
= 0.6d = 2.4 light years. The time taken by the rocket to make the return journey is therefore tr
= 2dr/v = 6
years.
= 0.6d = 2.4 light years. The time taken by the rocket to make the return journey is therefore tr
= 2dr/v = 6
years.
Therefore, on his return, the traveler is 4 years younger than his earthbound sibling.
However, if we use the Lorentz factor to define the appropriate units of time in the moving
inertial frame (rather than applying it to the number of light years involved) we have the
following set of calculations:
inertial frame (rather than applying it to the number of light years involved) we have the
following set of calculations:
The travelling twin will see the earth taking longer to orbit the sun, so his year is
longer than a terrestrial year.
longer than a terrestrial year.
Applying the Lorentz factor for a velocity of v = 0.8c,
we find that 1 year in the travelling twin's inertial frame is equivalent to 1.666666667
earth years;
we find that 1 year in the travelling twin's inertial frame is equivalent to 1.666666667
earth years;
As he sees it, the distance to the star system is therefore dr
= 4 x 1.666666667 =
6.666666667 equivalent terrestrial light years.
= 4 x 1.666666667 =
6.666666667 equivalent terrestrial light years.
His return journey time, measured on board the rocket, is therefore tr
= 2dr/v = 10
years.
In other words, when the travelling twin returns to earth he will be exactly the same age as
his earthbound sibling.
= 2dr/v = 10
years.
In other words, when the travelling twin returns to earth he will be exactly the same age as
his earthbound sibling.
The Twin Paradox is therefore a real paradox, and is of the falsidical kind. Indeed, it is very
similar to Zeno's paradox of Achilles and the tortoise. The fallacy at its heart is the
assumption that the units of time defined for the terrestrial inertial frame can be carried over to all external frames. This is expressly forbidden by Einstein's definition of time and would,
in any case, have the effect of making terrestrial time an Absolute Time, something, as we
have seen, that Einstein was at pains to avoid.
similar to Zeno's paradox of Achilles and the tortoise. The fallacy at its heart is the
assumption that the units of time defined for the terrestrial inertial frame can be carried over to all external frames. This is expressly forbidden by Einstein's definition of time and would,
in any case, have the effect of making terrestrial time an Absolute Time, something, as we
have seen, that Einstein was at pains to avoid.
Return To Top | Posted:
2017-10-24 01:17:52
| Speak RoundDebatorTerminator (CON)Round Forfeited
Return To Top | Posted:
2017-10-27 01:18:01
| Speak Round
This debate concerns this dimension, or our dimension only. There are other dimensions which our time system doesn't apply. The universe is divided into fractals. Each fractal has its own time/spin system. An atom runs via a faster time system based on spin rate. A galaxy runs at a slower rate based on galactic spin which is much slower than atomic spin rates. Posted 2017-10-25 09:09:08
ok so am not going into technicalities but for all i know is that time is a relative phenomenon.
but we humans have standardized ourselves in accord to this terminology "time". there are multiple universes abd dimensions each having their iwn set of possibilities for everything going on this minute speck called world. in some other dimension, i may just not be even typing this... but theoretically and philosophically speaking, yes time do change for good and bad but at the end it just adds up to be a constant... because as we know universe runs on stability and constant factors...Posted 2017-10-25 04:45:53