Blog 22

    Blog 22/ (Slides 4-6): FROM EINSTEIN TO SPACE-TIME – Though whether Minkowski space-time contradicts naïve impressions is still unclear.

  Albert Einstein was born into a prosperous firm of electrical contractors in 1879.   And at the age of 16 he wondered what he would see if he could chase a beam of light at the speed of light. 

    At first he thought he would see a frozen wave.  But then he realised this would be inconsistent with light’s constant speed.   This was a problem over which he reflected for a decade - before realising that those commonly accepted  consistencies for both time and space would have to be changed accordingly.

    In his “Electro-dynamics of Moving Bodies” (1905) Einstein then successfully  incorporated Maxwell’s laws of electro-magnetism with Newton’s laws of motion under Galileo’s Principle of Relativity.  Now known as the Theory of Special Relativity (SRT), it advanced several postulates since abundantly proven to be true. 

     These included time dilation and length contraction, two effects which progressively increase as one nears the ultimate barrier of light’s speed.

   SRT also incorporated Lorentz transformations and other ideas from previous researchers in the field.   These were all developed through algebra, which made the theory rather difficult to comprehend.   But above all SRT had no requirement for an aether – that confusing term for a non-existent entity which had held up progress for so long.

   It was 1916 before Einstein – aided by personal coaching in difficult non-Euclidean mathematics known as Riemann tensors – could produce a wider version of RT.  Now known as General Relativity Theory (GRT) this new version also brought Newton’s Law of Gravity under Galileo’s original Principle of Relativity.  GRT also required the use of curved space-time, a concept to which Einstein was originally opposed.

   The first experimental proof of RT then occurred in 1919, when British astronomer Sir Artur Eddington mounted a West African (and also Brazilian) expedition to photograph a solar eclipse in that belt of the globe.   While the sun was in darkness (for just 6 minutes) nearby stars would then become visible.  And GRT predicted that their light would be bent slightly inwards because of solar gravity.

   Eddington came back with just 2 rather unsatisfactory photographs, which still suggested that Einstein was correct.  (First experiments are “often messy” as Gell-Mann has pointed out.)   And over the next 20 years in any case, various other successful experiments all attested to the reality of RT.

    For the general public however, RT’s most dramatic proof came when the atom bomb exploded over Hiroshima in 1945.  This was unarguable proof of Einstein’s famed RT equation, E = Mc².  (Energy = Mass multiplied by the speed of light (=c) squared.)

   Thereafter throughout the sixties, atomic clocks grew smaller, going also far below one-billionth-of-a-second in their accuracy.  This led the US Navy to fly two such clocks around the world in opposite directions, testing whether their times would vary as RT said they should.   Once again the results of this Hafele-Keating flight (1971) proved Einstein correct, with about 10% accuracy overall.

    Wherefore the US military realised that a triangulating system of some 20 broadcasting satellites equipped with such clocks , could provide accurate geo-location anywhere on the globe.  This was the start of the Global Position System (GPS), later opened up in 2,000 by President Bill Clinton for general public use.

    So that timing by GPS now runs much of international communications, your car’s SatNav, the internet, driverless tractors for better farming, and of course the ubiquitous smartphone.  

    That the modern world then crucially depends on RT (in both Special and General form) is therefore evident.  So that we all now live by Einsteinian time, and despite its various contra-intuitive implications, is quite  clear…..

   Which also provides a fifth example of naïve impressions falsified by scientific knowledge.  For RT has proven that time and space are not really immutable, as common impressions would have us believe…..

   Hermann Minkowski had been Einstein’s tutor at the University of Zurich, being also a very distinguished mathematician in his own right.   So in 1908 he converted Einstein’s algebraic RT into a more geometrical and diagrammatic form.   This change conferred the great advantage of bringing one’s visual intelligence into play, so making RT easier to understand..

   An earlier example of visualisation through diagrams was provided by Euclid’s triangles from about 300 BC.  Their similarities and differences are much easier to discern than if they’d been expressed through algebra. (Which anyway was quite unknown in Euclid’s day).

    Since you can’t see a time except at a place – nor a place except at a time – Minkowski held that the two must always occur united together, in one inseparable 4-dimensional reality of space-time.   This he expressed through  a 3-dimensional drawing as shown here, with one of the three spatial axes omitted for simplicity.  

    The twin cones are bounded by the track of two beams of light which flash through the central point of Here-Now at their usual ultimate speed.   And since nothing can move faster than light, those ‘Elsewhere’ regions outside the twin cones, are forever inaccessible to objects or people from within.

    The vertical line through the centre is the worldline (or timeline) of an Observer at rest.  If produced for long enough it would represent his or her entire lifetime (with a likely maximum of 3 billion seconds) from womb to tomb.   Those other world-lines which intersect the main time-line, at points called events, belong to other people or objects.  Or more often the light-beams emanating from them.

    Each of these other world-lines has its own light cone and different time-line at angles dependent on direction and speed.  (Though these intersection angles are here greatly exaggerated for diagrammatic ease.)  Straight lines are for objects travelling in smooth relative motion, while acceleration would be depicted by a curve.

    Since information within the cone can only be transmitted by light speed at a maximum, what’s past for one observer may well be present for another, or even future for a third.  Whence likewise for each of these observers, judgement of Now is a purely local label, and with no special importance otherwise.

   This means that Minkowski futures are every bit as real as past ones, both cast within space-time which seems to constitute a strangely frozen entity overall.

   For space most people realise that our judgements of relativity depend purely on location, a matter so familiar that nobody ever bothers to argue about it. 

    Consider for example the relation between a chair and a table on a stage.  If a speaker stands back he may judge that the chair comes BEFORE the table, while to the audience out front the chair is obviously BEHIND.   And for observers to either side the chair may be judged as either to LEFT or to RIGHT accordingly.

    But few would be foolish enough to argue about which judgement is best here.  Instead it’s more sensible to realise that all are equally valid,  depending on where the observer happens to be.

   Not many however realise that a similar relativity of judgement holds for time.  This can be very difficult for our naïve impressions to appreciate.    But it can  be better appreciated if we consider a five-member family separated over 300 kilometres, each one of them also equipped with a very accurately recording smart-phone.

    If John’s phone above were to record two calls from DAD and MUM simultaneously, that would be only because the radio signal had the same distance to travel from both.   

    Conversely Jack’s phone would record that DAD phoned first (or earlier) - because of the lesser distance that message had to travel.   Whereas Jill’s phone would record the very opposite, with MUM’s transmission arriving earlier because she was so near.

    And while their sensory impressions would be too crude to appreciate such thousandth-of-a-second contradictions in timing, these would be quite within the recording capacities of their ubiquitous smart-phones.

    British physicist Sir Roger Penrose has likewise illustrated such contradictions in past-future judgements with his well- known Andromeda Paradox.  He imagines two people just strolling past each other at a leisurely two metres per second apiece.  Each must also be able somehow to see out as far as the Andromeda Galaxy two million light-years away.

    One person might then see the Andromedean people In a Star-Wars scenario, debating whether to fit out a space-fleet for some future war.  But the other might be observing that same war as past and finished long ago!

    So that this paradox illustrates the great differences in past-future observations and judgements, when RT is extended over long distances from two almost coincident starting points.

    All of which further proves that our experience of NOW is a purely local or personal judgement, with a difference of ten billionths of 1 second between two people just 3 metres apart.   And while fine timing to this degree is far below our sensory levels of time discrimination, it’s well within the capabilities of the GPS system which now runs the world.  

     That reality does consist of space-time in any case follows from various confirmations of GRT over recent years.   One such is the LIGO  discovery of gravity waves in 2015.  Another comes from the NASA Satellite B experiment a few years earlier, confirming relativity’s very slight warping of local curved space-time as the earth spins every day.

    In addition relativistic transformations – of one proper time to another in their associated frameworks – requires a 4-dimensional reality.  In this context Minkowski space-time can be compared to an unsliced loaf where time might be sliced out by one observer as a straight cut down the middle – so leaving the space dimensions to either side.

    Whereas another observer with different orientation in space-time would angle this first cut differently, transforming some of the other’s space into time and vice-versa.

   Nevertheless, even though the space-time concept is now as thoroughly proven as any other in physics, many observers still hesitate to pronounce on its ultimate reality.  And this denial is mainly because its psychological implications seem so totally in conflict with what our naïve impressions would have us know.

        

   The seeming psychological consequences of space-time, and its apparent ontology as a frozen version of reality, have been well realised  from the start.   So that one of the first to highlight them was astronomer was Sir Arthur Eddington, whose eclipse expedition in 1919 provided the first proof of GRT.

    And he was closely followed by quantum pioneer Prince Louis de Broglie, who emphasised the seeming progression  of consciousness into laid-out  future time.

    While Einstein in his last days refuted the commonly accepted difference between past, present, and future.   Though apparently before that  he never made much or any pragmatic investigation into the relevant psychology.

    The role of perception (or psychology) however begins to be stressed more forcefully by CERN physicist Costa de Beauragaard in The Voices of Time (1966).  While consciousness was also emphasised by Hermann Weyl, still much quoted nowadays after almost 100 years.

   But, apart from such theoretical considerations, the link between  consciousness and space-time’s contentious implications seems never to have been  investigated pragmatically so far.   Wherefore it’s something I will  consider more actively from this point on…

    To a certain extent also those conclusions I’ve just quoted resemble the very  ancient philosophy of Being – as opposed to the equally ancient and rival  philosophy of Becoming.    This is a debate still currently very much active, while stretching back to the very dawn of  Greek philosophy over 2,500 years ago.

    Heraclitus of Ephesus (ca.550 BCE) then instituted the philosophy of  Becoming,  with his still famous statement that  “You can’t step in the same river twice”.  So that  all things are forever undergoing constant change.

    Against which Zeno of Elea (ca. 450 BCE) advanced various ingenious and still relevant arguments for Being: he held that the external world is really static and change is only an illusion of our minds.

    So “Does time pass by us?” (Heraclitus) or “Do we pass by time?” (Zeno).   This still unresolved question resembles that other ancient debate on whether the sun is “passing round“ us  (as our naïve impressions would have us believe.)  Or alternatively whether it is we who are “passing round” the sun – as science now more definitely informs.

    Three good analogies, of our possible relation to time in this context, have also been proposed:-

   1/ Imagine your mind as a passenger on a train traversing the countryside of space-time, but crucially seated with its back to the engine throughout.  The present is that trackside pylon now looming up outside your window - and which you can further observe as it fades downline into the past (=passed).

    While if you could somehow twist your long-set mental muscles into a different direction, you could also observe those future up-track pylons before they come into present view !

   2/ Another good space-time analogy is provided by the familiar cinema experience.  Where your illusion of the changing present, is provided by slightly differing static pictures - projected on-screen at the rate of 23 frames per second, and with 23 pauses in between.

      While your past is contained in the reel already rolled up – and your future  in that other reel as yet unrolled!

    3/ This cinema experience can also be simplified if you imagine all reels rolled out into just one very long film-strip describing your entire lifetime.  Imagine further your consciousness  moves at a regular rate along above this strip of stretched-out film.  And with each still picture illuminated by strobe lighting at the cinema’s 23 flashes-per-second rate. 

    So that your static past and future are therefore equally coexistent to either side of your illusory present apparently forever undergoing change.

   Finally it’s worth noting that there have been four international conferences on the ontology of space-time (organised by the Minkowski Institute of Montreal) over the last ten years.   But with a notable dearth of pragmatic psychology in any of them….