Archive for the ‘Time’ Category

Where and when we are – a dimensional conundrum

September 7, 2021

“In physics and mathematics, the dimension of a mathematical space (or object) is informally defined as the minimum number of coordinates needed to specify any point within it”. – Wikipedia

In the concept of spacetime one might think that (x,y,z,t) are the four dimensional coordinates which are necessary and sufficient to specify the location of any object at any time within our universe. But that would be an oversimplification. It is true only for a relative location and not for any absolute location.

In reality we have no idea – in absolute terms – of where we are or when we are.

The place where I was born on the surface of the Earth has – during my lifetime – drifted along with the continents some 2.3 m North-East across the earth’s surface. The Sun (along with the Earth) has moved 6.9 billion km around the centre of the Milky Way Galaxy. Using referents outside the Milky Way Galaxy, it has, during the same time, moved some 55 billion km in space. So, I was born some 60 billion km away from wherever in space we actually are now. In the context of the Universe this is still local space, and I do not need to account for the very expansion of space. The looming collision of the Andromeda Galaxy speeding towards us is still 4.5 billion years away and irrelevant in the scale of my lifetime. Taking my present location as (0,0,0,0) and the X-axis as the straight line from where we were then to now, the coordinates of my birth location become (-60, 0, 0, -73 years) where x, y and z are measured in billions of km.

Everything is relative to here and now.

It is not even certain that time is actually a dimension of the same kind as the 3 physical dimensions we perceive. Some think it emerges together with the Universe and everything. Others think it is just a facet of existence. In any event, we only experience it as a backdrop for, but separate to, our own individual existences. On the stage of our existences, we strut and fret our hours away, but we cannot interact with or impact the relentlessly moving backdrop. Just as with nonsense rhymes using language, nonsense equations by learned physicists about the theoretical access to past times is just nonsense. As with any language, mathematics can also describe the unreal and the nonsensical. Speculative cosmologists have more in common with Edward Lear than they would like to think.

Considering time to be a dimension is no more than a convention or, at best, an analogy. It does not help either, that

  1. we have no clear definition (or understanding) of what a dimension is, and
  2. we can take a dimension to be anything that can be counted.

We can measure the oscillation of apparent motions and assume that such motion is regular and then infer the passage of time. But what time is other than a magical, necessary backdrop for everything is beyond our comprehension. We cannot be certain that a second now is the same, or longer, or shorter, than a second at some other time. (A second now must be longer than a second was then).

The world is what our perception tells us it is. But our perception is limited, and it limits the boundaries of our reality. We perceive space and everything around us as having 3 dimensions, yet we cannot truly conceive of any real thing having other than three spatial dimensions. In our 3-dimensional world we can define one- and two-dimensional things only as concepts (lines and surfaces) but we cannot identify any real-world objects which have only one or two dimensions. Moreover, real things having more than 3 dimensions are beyond our comprehension. How a fourth spatial dimension could be manifested lies outside of human reason. We have the language to describe – but only conceptually – any number of dimensions. Scientists and mathematicians speculate about 3 or 7 or 9 or infinite dimensions and claim either that 3 is the most probable or theorise that the others are hidden in the strings that make up the world, but the human brain can only perceive 3. (I note in passing that invoking the infinite is itself an admission of incomprehensibility). It is a fruitless and inevitably circular discussion to question whether it is our perception which is limited to 3 dimensions or whether the universe has only three to be perceived. Our universe is enabled, and strictly constrained, by what our cognition allows us to perceive. Every real thing in our universe has three spatial dimensions; no less, no more. Our universe has 3 spatial dimensions because that is all, and only what, we can perceive.

I probably read “Flatland” as a teenager where a sphere in Flatland can only be perceived as a circle.

Flatland: A Romance of Many Dimensions is a satirical novella by the English schoolmaster Edwin Abbott Abbott, first published in 1884 by Seeley & Co. of London. Written pseudonymously by “A Square”, the book used the fictional two-dimensional world of Flatland to comment on the hierarchy of Victorian culture, but the novella’s more enduring contribution is its examination of dimensions. – Wikipedia

No matter how many dimensions the universe may have, three dimensions is all human cognition can ever perceive. It is that reality which constrains all our thought. It becomes a fundamental assumption for science which the scientific method cannot penetrate. If other dimensions exist, then what we perceive in three are projections. As a shadow is perceived to be two-dimensional. But to have a projection or a shadow in our 3-dimensional world we would need some kind of cognitive light from the other, higher dimensions to create what we perceive.

But human cognition is limited. We cannot perceive what we cannot perceive. And we have no clue – earthly or divine – as to where and when we are.


Once upon a time, a leap-second …..

December 31, 2016

Leap seconds were invented in 1972 (in which year we had 2 leap seconds, one in June and one in December). In 26 of the 44 years since 1972 we have had leap seconds. A year with a leap second happens more often than a year without. Today we add the 27th leap second since its introduction.

A leap second is a one-second adjustment that is occasionally applied to Coordinated Universal Time (UTC) in order to keep its time of day close to the mean solar time, or UT1. Without such a correction, time reckoned by Earth’s rotation drifts away from atomic time because of irregularities in the Earth’s rate of rotation. Since this system of correction was implemented in 1972, 26 leap seconds have been inserted, the most recent on June 30, 2015 at 23:59:60 UTC, and the next leap second will be inserted on December 31, 2016, at 23:59:60 UTC.

Having a leap-second is the new normal.

Deviation of day length from SI based day – Wikipedia


 

The consumption of time

September 7, 2016

No change without the passage of time.

No passage of time without change.

That is almost trivial. It does not help to tell us what or why time is.

Or perhaps it does.

Perhaps time is a consumable. It is the fuel that is needed for and is consumed by change. Quantum of change per unit of time taken as miles traversed per gallon of fuel. It follows that we can stop the passage of time if we can stop change – down to the motion of the elementary particles. Time does not just pass – perhaps it has to be consumed.

Perhaps the single great mystery is gravitation. Then gravitation (or gravitational energy) is manifested as the passage of time. The speed of the passage of time then varies with the gravitational field. One real second per perceived second now, but perhaps zero at the Big Bang.

The magical speed of an inconstant time

speed of time

No time without gravity.

And no change without time being consumed.

So, no change without gravity and time is just the medium of change.


 

“Let there be cesium” and there was a leap second

June 28, 2015

On 30th June 2015 at 23:59:60, a leap second will be added before 1st July 2015, 00:00:00 because the difference between Coordinated Universal Time (UTC) and Universal Time (UT1) would have reached 0.9 seconds. Universal Time also known as Astronomical Time is based on the Earth’s rotation around its own axis, which determines the length of a day. Since 1972, 25 leap seconds have been inserted to synchronise these two clocks and this leap second will be the 26th. The differences are so irregular that the need for a leap second cannot be predicted more than about 6 months in advance.

The leap second is for synchronising the two clocks and not – directly – for compensating for the slowing down of the earth and the lengthening of the day. That adds about 1 second every 58,800 years (1.7ms per century). Since modern humans arrived on the scene some 200,000+ years ago the length of the day has increased by about 4 seconds.

International Atomic Time (TAI) is the “standard” used to synchronise the other two clocks and is built up by combining the output of some 200 highly precise atomic clocks worldwide and where the second is defined by the resonant oscillation frequency of cesium 133.

Atomic clocks use the second as the base unit and hours, days and years are taken to be multiples.

“The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom.”

The wise men of our age believe (they cannot know) that this resonant frequency of the cesium 133 atom will remain “stable” for millions of years and is far more stable than the period of rotation of the irregular orbit of the earth around the sun or the even more irregular (and slowing) rotation period of the earth on its own axis.

All we measure, or try to measure, are periods of time – provided of course that time exists. Cesium would not have come into existence until about 3 minutes after the Big Bang, but time, presumably, began with the Big Bang. Initially there was only hydrogen and then came Big Bang Nucleosynthesis (BBN), which after about 10 seconds (cesium 133 seconds, though cesium still didn’t exist) started producing helium. The heavy elements came about 3 minutes after the BB and after about 20 minutes BBN ceased. Light would have been created as soon as the fusion of hydrogen started with the BB itself.

Rephrasing Genesis

The Big Bang was the Beginning and then came Fusion. The expanse was without form and void, and dark energy was over the face of the deep. And the Spirit of Gravity hovered over the face of the aether. And Gravity said, “Let there be Coalescence” and the stars of the heavens came to be. “Let there coalesce a Sun” said Gravity, and so there was light. “Let coalescence proceed” and under Gravity came the earth bathed in the light of the Sun. And the light was good. 

And the rest is history.

 

Aliud orbita et hoc anno

December 23, 2014

Another orbit, another year.

Since the Earth – recognisable as a condensed planet – started rotating around the Sun, there have been an estimated 4.54 ± 0.05 billion rotations (4.54 × 109 ± 1% revolutions). From the time humans – recognisable as modern humans – walked the earth, there have been over 200,000 revolutions. The number 2015 is measured from an arbitrary and a rather meaningless point in time and – for the SUN or the Earth – has no significance whatever. It is just a label for the coming year.

In any event the lucky number for “2015”  is 8.

Sol et manet invictus. (And the Sun remains invincible).

sol invictus 2014

 

Have a wonderful year!

Turn and turn again and behold we have time

December 22, 2014

The winter solstice has passed. The longest night is almost over and the days will start getting longer again.

Turn and turn again and behold we have time.

We are surrounded and dominated by cycles. Without periodicity and cycles we would have no concept of time.

Daily cycles, monthly cycles, annual cycles, solar cycles every 11 years, the earth’s precession cycle with a period of 26,000 years, the earth’s axial tilt cycle of about 41,000 years and the Milankovitch cycles of about 100,000 years, are just some of the cycles that surround us.

Whether everything derives from the vibrations within the most fundamental particles and then are manifested by the periodic motion of bodies in our cosmos or whether the motion in the cosmos is the origin of everything else, periodicity and cyclic behaviour is ingrained within us and our world.

 

 


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