The Physics and Philosophy of Time: Part One

“What is time?” That is a question that has been pondered and debated for probably thousands of years by some of the finest philosophical and scientific minds ever produced, without any definitive resolution. So, I’m NOT going to pretend that this is THE ANSWER – the be all and end all to the question. It’s some of my thoughts, which hopefully are as valid as anyone else’s!

What Is Time? It has been said that time is just Nature’s way of preventing everything from happening at once! But the word ‘happening’ is significant because if something happens, something changes. To my way of thinking, time is synonymous with change; time is a measurement of change; change gives the concept of time tangible meaning. If nothing ever changed, if nothing ever happened, it would be meaningless to talk about time. Time is just our informal perception or more formal measurement of rate-of-change. Rates-of-change vary depending on how fast you travel relative to some other frame of reference (the General Theory of Relativity) so the time intervals that measure that rate-of-change vary accordingly. I also can’t help but wonder whether, speaking of things relative, whether one could insist on a constant rate-of-change that’s made constant because your rate-of-time varies, or the more common view from day-to-day experience that rate-of-time is constant but rate-of-change varies.

It’s not difficult to understand why you are not aware of time passing when you sleep. It’s because you’re not aware or cognoscente of anything changing while you’re asleep. In fact, sleep is a way of achieving time travel. You go to sleep at 11 pm. Next thing you know its 7 am and you’ve traveled eight hours into the future seemingly instantly!

Thusly, I conclude that time doesn’t have a separate reality. I mean you can’t weigh time, it has no mass, it has no charge or energy, it isn’t a force and has no particle associated with it, you can’t put time to any physical use, nor can you manipulate time. You certainly can’t bottle and sell it! It’s about as intangible a something as the Universe allows.

Did time exist before there was anyone around to put a label to it? I mean in a pre-life era, change certainly took place – rocks eroded, the tides ebbed and flowed. But was there time? I suggest the answer is ‘no’ in that it takes a certain level of intellect to recognize change or rate-of-change. A rock doesn’t perceive time, nor does the beach upon which the tides act. The changes are physically real enough, but it takes something as complex as a living organism (not of necessity just a human organism) to perceive and understand change, and rate-of-change, which – human beings – for lack of a better word, we call it all happening (i.e. rate-of-change) as a concept called ‘time’.

By analogy, there is the oft quoted puzzle of there being this tree in a forest which falls. Does the falling/fallen tree produce any sound if no one (meaning humans) is around to hear it? (Of course there would be animals like bears, deer, possums, birds, etc. that would hear the sound, but let’s suppose that the forest contains just plants which I assume we can agree on, can’t hear. Now regardless of whether any animals are around or not, the falling tree will produce vibrations in the air (usually air, but vibrations can be equally transmitted in a liquid or solid medium). But vibrating air isn’t by itself sound. Sound is the perception (and possible interpretation) of those vibrations, and that takes a detection device and software (ears and a brain). So, there is no sound without ears and a brain, although the vibrating air is quite real regardless.

Time too, by way of my analogy, is akin to sound; change or rate-of-change is akin to the vibrating air. The former two (time and sound) are perceptions of physical events; the latter two (change and vibrating air) are the real physical events.

You’d think that therefore time wouldn’t exist in a vacuum or at a temperature of absolute zero, as how could anything change in a vacuum which contains nothing or at absolute zero when all motion ceases? Ah, enter the weird and wonderful world of quantum physics and discover that quantum activity, happenings, change, motion, etc. exists even in an apparent perfect vacuum and even at as close to absolute zero as makes no odds. In quantum physics, there’s no possibility of a perfect vacuum; absolute zero is only abstract and can’t ever be actually achieved. Therefore, time always exists as well. There seems to be no way to ever shut down quantum activity and achieving a perfect vacuum and/or absolute zero, so we’re in no danger of ever having our perception of time cease.

The shortest (quantum) unit of time possible is just that interval below which no possible change can happen. In other words, even the quickest ever possible change one can imagine takes an absolute minimum amount of time.

Change also implies there must be causality – there must be a cause that produces an effect, or in other words, something is affected by something else that occurred previously. Going from cause to effect implies a change and a time interval must have taken place into which that change fits. This introduces the commonly used phrase ‘arrow of time’. If time is our perception of change, then what is the ‘arrow of time’? Methinks it’s the reality that on the macro scale at least change happens only in one direction – cause precedes effect; effect follows cause, and that’s change. Examples of such one way cause and effect change include dropping the china cup and it breaks. A broken cup does assemble itself and then leap off the floor into your hand. Humans tend to be conceived, get born, grow up and age. Hair turns gray (or falls out), you get wrinkles and liver spots, and you die. You don’t rise from the grave, re-animate, and age backwards towards childhood and pop back into the womb! A hot cup of coffee cools off to room temperature. A cold cup of coffee doesn’t heat up by itself; even if there’s potential energy enough in the environment (air molecules flying around) to theoretically heat it up.  In other words, you can’t unscramble (or un-boil) an egg. 

Present Time: The Concept of ‘Now’: Does the present actually exist? We speak of it was if it does. But does it? Now I’m sure there’s no debating that there is a past, and that there will be a future. I’m sure there’s no debating that what we’d call five years ago exists in the past; five years on from when you read this is clearly the future. What about five months ago, or ahead?  What about five days or five hours or five seconds? Is half a second ago the past? Is half a second hence the future? Of course it is. In fact, I suggest you can split units of time ever shorter and shorter, but still admit that ‘ago’ means past; hence means future, even if 0.000005 of a second ago really is past, and 0.000005 of a second hence is the future. So where comes the ‘now’ or the present?

While there is a past, and will be a future, there really does exist a present. There apparently is such a thing as the shortest interval of time and nothing shorter can exist in reality. That shortest interval of time is known as Planck-Wheeler time, below which time as we know it ceases to exist. It’s about 10 to the minus 43^rd of a second. That’s how long your present lasts for! One Planck-Wheeler time unit behind you is now forever locked in as part of your unalterable past. One Planck-Wheeler time unit ahead, is still part of your malleable (free will?) future.

Even without resorting to quite such a tiny present, physics logic suggests that you really are an isolated individual that cannot share the present with the rest of the world. Lets imagine this couple, say we call them Clive and Jane, sitting down for their evening meal. Clive says to Jane, “pass the salt please darling”. Now Clive utters that phrase in his present and Jane hears it in her present. But both presents aren’t simultaneous. When Jane hears it in her present, it’s simultaneously Clive’s past because it takes time for sound to travel from voice to ear (and light from mouth to eye). Actually, when Jane hears the word “salt”, “pass the” is already in her past while “please darling” is still in her future. In other words, Clive and Jane can’t ever share the same present even though both pass through identical simultaneously now’s.

Here’s a form of time travel. When Jane looks in a mirror, the image she sees in her present is actually of herself from her past – an ever so slightly younger version of herself because it takes an interval of time for the light to be reflected off Jane, onto the mirror, reflected off that, and back to Jane’s eyes.

In summary, nothing you see or hear has the exact same reality that you perceive in your present because there has been a time lag and things change over time – even incredibly short intervals of time. A common example is looking at a distant star. The star you see in you’re here and now isn’t the same star that exists in that same here and now. You’re looking at a star, which, for all you know, just may no longer exist!

Of course you do live your entire life in the actual ‘now’ – you certainly don’t literally live in any part of your past, nor your future. Your life, your lifetime of ‘now’, is a string of Planck-Wheeler time units.

It’s About Time – For a Change: Part One

Introduction: The real nature of what we call ‘time’ is one of the Big Questions. It’s been debated ever since humans evolved thought and language. That puzzlement remains true to the average person today, although ‘time’ has become the professional subject or province of philosophers, metaphysicists, and theoretical physicists, not to forget many a science fiction author! Here’s my two cents worth – ‘time’ is an illusion!

What Is Time? Time is, IMHO, an illusion. Time has no real independent existence – it can’t stand by itself. If you removed all the matter and energy from the Universe, would there be left anything we could address as time? Time is just our way of keeping track of, and measuring rate of change in matter and/or energy. If nothing ever changed it would be nonsense to talk about time. The flow of time; the arrow of time; is just the flow of macro things changing. If everything were somehow ‘frozen in time’ – like a single frame from a film – then there is no actual time that can be discussed or measured. So we don’t in any sense measure something that is time, we measure rate of change and call that time.

Actually you measure rate of change by another rate of change. For example, the rate of change from birth to death is usually measured by the rate of change in position of the Earth orbiting the Sun (years and fractions of years) and rate of change of position of the Earth rotating around on its axis (days and fractions of days). Another example: The rate of change between the beginning of your lunch hour and the ending of your lunch hour is usually measured by the rate of change of the hands of a clock (sixty 360 degree sweeps of the minute hand or a 30 degrees clockwise change in the hour hand) or the rate of change in the numbers on your digital watch, say from 1:00 to 2:00. Translated, a variable or uncertain rate of change (lifespan; length of a lunch ‘hour’) is usually measured by a standard, invariable, predictable rate of change.

Now rate of change is affected by gravity – a function of mass – the greater the mass the greater the gravity and the slower things change from A to B in that gravitational field, but that slowness is only relative to someone else also measuring A to B but who is in a lesser gravitational field. A clock at the top of a tall building (lesser gravity being further from Earth’s centre) ticks at a faster rate than an identical clock at street level (which has higher gravity due to being closer to Earth’s centre). Rate of change is also affected by velocity. The faster you go, the slower things change from A to B, again however it’s relative to someone else also measuring A to B but who is moving at a lower velocity relative to you. That’s why it’s the theory of relativity! The standard example is the twin paradox – if your identical twin zooms off in a spaceship at extreme velocities to the distant stars, stops, reverses direction, and returns at that high rate of speed to Planet Earth, and to you, you’ll find your twin has aged to a far lesser degree than you. You now have grey hair and wrinkles; your interstellar travelling twin is still in her youthful prime of life.

Time vs. Time Travel: I’ll poor water on this fire at the outset by stating again that time is but an illusion. Time doesn’t exist; therefore time travel isn’t possible. Time is but a label, like your own name is but a label, and has no more reality than the label ‘Wednesday’. We just arbitrarily call every 7^th ‘day’ Wednesday, but you can no more hold Wednesday in your hands and you can time. Time, repeating myself, has no independent reality. You can’t assign any physical properties to the concept. I mean time isn’t a solid, it isn’t a liquid, and it isn’t a gas. Time has no size, weight, colour, texture, density, it doesn’t vibrate or have a wavelength, ditto no odour or flavour, it has no temperature or pressure, it doesn’t consist of any known combination of known forces and/or elementary particles, it corresponds to no known element or compound. You can’t pour time into a bottle and store it; you can’t confine time in a force field or in a prison cell or trap it on a piece of sticky fly paper. Therefore, if time has no substance, one can not actually travel through time.

What we perceive as ‘time’ is, again repeating myself, nothing but change – change in our environment; in our natural world; in our mechanical devices; and even in ourselves and associated companions (animal and human). Repeat – time is but an illusion. Change is real (cause and effect) since it involves forces and particles; energy and matter, the sorts of things that when you kick them, they kick back. We measure ‘time’ by the rate things change; rate of change is what we call ‘time’. Repeat - it’s the change (in something) that is real. 

Now on the macro scale, that is scales we interact with on a day-to-day basis, change appears to all intents and purposes to go one way (usually from a state or high order to a state of disorder) and so we view time as flowing from past to present to future – in one direction; order to disorder – past to present to future. But change in just one direction (order to disorder – past to present to future) is ultimately a function of numbers and probability. The simple illustration is to introduce a drop of ink into a bowl of water. That’s a high order situation. Now left to itself, there will be a change. The ink will disperse throughout the bowl of water. That’s a state of disorder. If a disordered uniform mix of ink and water separated all by itself into a drop of pure ink and a bowl of pure water (high order), that too is change, but we would interpret or view such an event as going backwards in time. If you viewed such a happening on film, you’d immediately conclude the film was being run backwards.

There’s a far greater probability for individual ink particles to spread out throughout a large volume than to come together in a small space. There’s lots of pathways to spread out; far fewer pathways to come together. But at the micro level, the level at which those individual ink particles do their thing, they don’t care where in the bowl of water they are. They are just as ‘happy’ to be all together as a drop of ink, as dispersed and diluted. If they do come together as a drop of ink from a dispersed/diluted state, that’s statistically unlikely, but such an event violates no laws of physics. It would be going from a state of maximum disorder to a highly ordered state; or, from an apparent future to present to past ordering. Such a change would appear for all practical purposes as apparent time travel – going backwards in time.

The catch – there’s always a catch – is while all those ink particles are defying statistical probability and undergoing apparent time-reversal, the rest of the cosmos is acting in a statistically normal way – going forward in ‘time’. So, perhaps we have a Universe where for 99.9999% of the time, 99.9999% of events within the Universe march to the beat of the standard past – present – future ordering of things. That is, in terms of change happening in a statistically probable way. While now and again tiny pockets of the Universe reverse direction, they do so at least just temporarily.  One can only defy statistically probability for only so long. So the ink particles come back together again as a drop of ink within a bowl of water – then what? They no doubt reverse direction again and proceed normally.

An analogy might be that while some individuals are winners while playing the slot machines (high order), the club still rakes in the profits from the vastly greater majority of (disordered) losers, and that no doubt the few highly ordered winners will eventually descend into a state of disorder and contribute ultimately to the club’s profit margin! It’s more statistically likely for a winner to become a loser than for a loser to become a winner.

Consider electrons. On average, any given electron has a very high probability of participating in a changing set of circumstances consistent with statistically probability. That is, the electron is moving forward in ‘time’. But if in those rare (loser to winner) occasions the changing set of circumstances goes against the grain of statistically probability, then we would view that electron as moving backwards in ‘time’. But there ultimately is no backwards or forwards in time, just change which statistically goes or moves in one general direction (order to disorder), but which can now and again, albeit briefly, go the reverse direction (disorder to order).

To belabour the point, what we call the past is change which has already happened; the present is change which is happening; the future is change that will happen.

To be continued…

Time Reversal: Studies in Time and Motion: Part Two

Time reversal is not the same as actual time travel, rather its pseudo time travel in the sense that time reversal is more akin to a thought experiment yet one you can often perform with a motion picture camera. I’ll explain…

Continued from yesterday’s blog…

Things left to the natural way of things tend to go downhill not uphill. That’s gravity for you. Things traveling uphill better be expending energy, if they aren’t then you are probably in The Twilight Zone. It’s the old saying ‘what goes up, must come down’, and thus Newton’s apple bonked him on the head instead of doing a Superman imitation. Film a waterfall. Reverse the film. Oops!

Things that don’t have front-back symmetry left to the natural way of things tend to move in one direction, and if you see the reverse, it looks odd. Humans and companion animals tend to move forward, not backward. The same applies for most modes of transport – you don’t normally pedal a bicycle backwards just like you don’t drive to work in reverse, and aircraft certainly don’t fly backwards. But things with front-back symmetry can, like a balloon or a rocket taking off vertically. [But said rocket, once it turns on its side loses front-back symmetry and hence looks weird flying backwards.]

The key to all of this interpretation of time reversal, IMHO, is motion, or change (there can be no change without motion and vice versa). Filming something that’s standing still (no motion; no change) and playing the film backwards is a no-brainer for ‘there’s nothing strange happening here’.

Motion (or change) can be exhibited as left-right (LR), forward-back (FB), down-up (DU) or bottom-top (BT) or a mix of the three. Since time is a measurement of rate of change (or motion), all motion (or change) must have in addition a time dimension to it. If it didn’t have a time dimension to it, it’s rather silly to talk about a time reversal!

Motion of course can also be constant per unit of time, or variable per unit of time. Reversing the former is not as strange as reversing the latter.

Now for some general observations - first and foremost with respect to all things anomalous or weird, might I suggest that all else being equal, time reversing objects with high symmetry or no symmetry tends to be less weird than something in-between. So filming an amoeba, an asteroid rotating or a cloud forming, moving and dissipating (no symmetry) or a sphere in motion (a ball, a balloon) or a cube (say a dice), or a rotating tire or a Black Hole (high symmetry) isn’t likely to appear strange.

Time reversing things with LR and FB symmetry, or BT asymmetry, like rockets, pencils, trees/plants (in the abstract), dry spaghetti, mountains (in the abstract), tornadoes (in the abstract), and CDs/DVDs, don’t tend to appear too anomalous over the short term, at least if they aren’t moving. If they are moving, then things might look odd, but within bounds of reasonableness. Of course the CDs/DVDs might be rotating the wrong way and playing from outer edge to inner edge; the rocket might be landing with all motors firing instead of taking off. Of course if filmed for a long enough period, as in time-lapse photography, you’ll find it odd that plants shrink instead of grow, mountains don’t erode away but grow higher, and pencil points don’t become blunt but ever sharper.

Time reversing objects with only LR symmetry (vertebrates; most modes of transport like cars and planes and boats) tends to look odd. Land animals and automobiles don’t tend to walk/drive backwards; fish and boats don’t tend to swim/tread water backwards; birds and planes don’t tend to fly backwards.

Time reversing a change in symmetry from high to low is not overly anomalous, but low to high is usually considered strange. Examples: A punctured tire (originally LR, BF, BT) deflating to (LR, BF) isn’t strange; the reverse is. A pencil (LR, BF) falling over from the vertical (its radial symmetry broken) isn’t anomalous, but the view in reverse is. When a car (LR symmetry) crashes (zero symmetry), that’s normal – a car un-crashing most certainly isn’t.

Time reversing inanimate objects (still life – natural or man-made) tends towards the less anomalous, so filming, over the short term, a cliff face, or a painting, doesn’t look all that strange in reverse.

However, most artificial, man-made objects, tend to have a purpose(s) which for the most part doesn’t include just sitting there looking pretty, like a painting. If such objects have a purpose, then they tend to have a before and after aspect to them - if before and after tends to be the same as after and before, then things will look the same in reverse. However, the nature of the before tends to be different than the nature of the after, so reversing the two will probably be noticed – and odd. For example, place the white bread in the toaster and toast. The bread pops up toasted. Now reverse and you go from toasted bread to un-toasted bread. Or, throw your dirty dishes in the dishwasher and wash them. Take your nice clean dishes out. Reverse the film and you now put clean dishes in the dishwasher, apparently ‘wash’ the dishes, and take out dirty dishes!

Time reversing simple animate objects is less anomalous than time reversing complex organisms. If I viewed a bacteria’s behavior for an hour, and my cat’s behavior for an hour, filmed same and reversed same, I bet I could tell that the film of the cat had been reversed, but not nearly as certain about the bacteria.

Things get odd if you time reverse events dependent upon not space, but on time itself, so time reversing objects that by their nature are affected by the passage of time will be more anomalous than objects that aren’t. Film an electron for a million years and reverse – yawn. Film a rock for a million years and reverse. Over a million years, a rock will tend to erode, so the reverse is an apparent violation of entropy. Film a drop of blue ink placed and entering a glass of water at its surface and let time strut its stuff. Reverse the picture and you have a glass of pale blue water becoming clearer as all the blue bits come together at the surface in what appears to be a drop of blue ink. That’s odd. Film a hot cup of coffee and place a thermometer in it. The mercury in the coffee thermometer goes up and levels off. Place another thermometer next to the cup of coffee. Over time, the coffee’s thermometer registers lower and lower temperatures as the coffee cools; the outside thermometer gains a bit in temperature as heat from the coffee warms up the surrounding area. Now reverse. The coffee appears to get warmer and warmer; the adjacent area cooler and cooler. That’s also odd.

Time reversing objects moving LR or FB will tend to exhibit less anomalous behavior relative to DU/BT. So, two tennis balls, one each entering upper right and lower right move towards the centre, collide, and rebound each moving off stage towards the upper left and lower left. Reverse the film – nothing strange. But, drop a tennis ball and it goes top bottom, bounces bottom top, stops, goes top bottom, etc. until friction takes its toll and the ball comes to rest on the surface. Played in reverse, a motionless ball starts vibrating, jiggling, and then bouncing ever higher and higher. That looks very odd indeed. Or, Humpty Dumpty shuffles across the garden wall left to right – reverse and Mr. Dumpty shuffles right to left. But, if someone pushes Mr. Dumpty off the garden wall and Humpty falls down and shatters, the reverse looks odd. Why? Basically, I think its because top bottom/bottom to (or up down/down up) is associated with gravity and gravity is a one way (pull) force. Time reversal makes gravity a push force, something that’s well outside our day-to-day experiences.

Time reversal of steady-as-she-goes motion (constant velocity) is bound to be less anomalous than accelerated motion. A tennis ball moves at constant velocity left to right; ditto right to left in a reversal. A tennis ball hit by the server decelerates (due to friction) as it moves toward the opposite court. If the opposing player returns the ball in the normal course of events, then the ball will also be decelerating as it approaches the original server. Reverse the film, and when you get to the original beginning, the original server finds the ball accelerating as it approaches. How very odd. 

Time reversal in the micro world is a lot less anomalous than in the macro. Drop a uranium atom and a piece of dry pasta in a pot of boiling water. Reverse the picture. Which now looks odd – the micro or the macro? In the world of the micro, an electron and a positron meeting up for a date will quickly find their relationship in strife as they mutually annihilate and give off energy. But, the reverse is also possible. The vacuum energy can spontaneously produce matter-antimatter particle pairs. Now look at a chemical macro situation. An acid plus a base will react to form a salt and water. For example, the base sodium hydroxide (NaOH), will react with hydrochloric acid (HCl) to form table salt (NaCl) and water (H2O). But note that salt water, brine – our oceans – don’t revert naturally back into sodium hydroxide and hydrochloric acid. Chemical reactions that proceed of their own accord in one direction can of course be reversed, but it takes a bit of prodding. Without evidence of that prodding, the reverse reaction looks odd. So, running a film of that chemistry experiment backwards will look odd.

Summaries:

There’s nothing strange happening here: Still life. Motion too can be within this category. Toss a ball up in the air and it comes down again. If you reverse that, you still get an up and then down trajectory. Dig a hole and make a pile of dirt; take a pile of dirt and drop it into a hole.

That’s possible: A rocket ship can blast off and head straight up; a rocket ship, all engines blasting, can descend and land. While that’s certainly not the way the Redstone, Atlas, Saturn rockets and space shuttle worked, it’s possible, as the Lunar Surveyors and LEM and how the Mars Viking surface craft, landed. It’s possible to film the launch of a V-2 and reverse the film and conclude that such an event was possible.

That’s odd: Events showing objects without front-back symmetry moving contrary to expectations is certainly odd, but possible. Humans can walk backwards. Cars can travel in reverse gear. Birds can fly backwards if the wind is strong enough; ditto fish if the current is strong enough. Seeing a plane fly backwards is probably odd enough as to send you heading off to see the optometrist, the shrink, or attend AA meetings. 

That’s really weird and highly improbable: You’d place viewings of apparent violations of the 2^nd ‘law’ of thermodynamics (like a box of air molecules all moving in such a fashion that the faster/warmer molecules congregate in one half of the box and the slower/cooler molecules get together in the opposite half); and events hinting at antigravity, in such a category. Another case might be relativities so called ‘twin paradox’. Take two identical twins. One stays at home and the other boldly goes and travels at near light speed to a faraway destination somewhere out there, then reverses direction and heads for home. Upon arrival home, the boldly going twin appears a lot younger than her stay-at-home twin sister. Reverse the chain of events and you’ll have the stay-at-home sister growing younger as a result of her twin gallivanting around the cosmos! Take an inflated balloon and pop it, or let go of the end and watch it fly erratically around. Reverse that image. You’re sure to bet your life’s savings which viewing is forwards and which is backwards.

That’s impossible: There’s only one real example here. Film a macro object entering a Black Hole. Reverse the film. Since nothing (except Hawking radiation) can escape from the gravitational pull of a Black Hole, any film showing such an event is not just suspect and highly improbable – it’s flat out impossible.

Conclusion: Watching film in reverse can be fun and if you think about what you’re watching – the behind the scenes – educational.

Time & Time Travel: Part One

WHAT IS TIME? ‘What is time?’ exactly is a question that has been pondered and debated for probably thousands of years by some of the finest minds ever produced, without any definitive resolution. So, I’m NOT going to pretend that this is THE ANSWER – the be all and end all to the question. It’s my thoughts, which hopefully are as valid as anyone else’s!

It has been said that time is just nature’s way of preventing everything from happening at once! But the word ‘happening’ is significant because if something happens, something changes. To my way of thinking, time is synonymous with change; time is a measurement of change; change gives the concept of time tangible meaning. If nothing ever changed, if nothing ever happened, it would be meaningless to talk about time. Time is just our informal perception or more formal measurement of rate of change. Rates of change vary depending on how fast you travel relative to some other frame of reference (Theory of Relativity) so the time intervals that measure that rate of change vary accordingly. I also can’t help but wonder whether, speaking of things relative, whether one could insist on a constant rate of change that’s made constant because your rate of time varies, or the more common view from day-to-day experience that rate of time is constant but rate of change varies.

It’s not difficult to understand why you are not aware of time passing when you sleep. It’s because you’re not aware or cognoscente of anything changing while you’re asleep. In fact, sleep is a way of achieving time travel. You go to sleep at 11 pm. Next thing you know its 7 am and you’ve traveled eight hours into the future seemingly instantly!

Thusly, I conclude that time doesn’t have a separate reality. I mean you can’t weigh time, it has no mass, it has no charge or energy, it isn’t a force and has no particle associated with it, you can’t put time to any physical use, nor can you manipulate time. You certainly can’t bottle and sell it! It’s about as intangible a something as the Universe allows.

Did time exist before there was anyone around to put a label to it? I mean in a pre-life era, change certainly took place – rocks eroded, the tides ebbed and flowed. But was there time? I suggest the answer is no in that it takes a certain level of intellect to recognize change or rate of change. A rock doesn’t perceive time, nor does the beach upon which the tides act. The changes are physically real enough, but it takes something as complex as a living organism (not of necessity just a human organism) to perceive and understand change, and rate of change, which – human beings – for lack of a better word we call it all happening in a concept called ‘time’.

By analogy, there is the oft quoted puzzle of there being this tree in a forest which falls. Does the falling/fallen tree produce any sound if no one (meaning humans) is around to hear it? (Of course there would be animals (bears, deer, possums, birds, etc.) that would hear the sound, but let’s suppose that the forest contains just plants which I assume we can agree on, can’t hear. Now regardless of whether any animals are around or not, the falling tree will produce vibrations in the air (usually air, but vibrations can be equally transmitted in a liquid or solid medium). But vibrating air isn’t by itself sound. Sound is the perception (and possible interpretation) of those vibrations, and that takes a detection device and software (ears and a brain). So, there is no sound without ears and a brain, although the vibrating air is quite real regardless.

Time, to by way of thinking, is akin to sound; change is akin to the vibrating air. The former two are perceptions of physical events; the latter two are the real physical events.

You’d think that therefore time wouldn’t exist in a vacuum or at a temperature of absolute zero, as how could anything change in a vacuum which contains nothing or at absolute zero when all motion ceases? Ah, enter the weird and wonderful world of quantum physics and discover that quantum activity, happenings, change, motion, etc. exists even in a perfect vacuum and even at absolute zero. Therefore, time exists as well. There seems to be no way to ever shut down quantum activity, so we’re in no danger of ever having our perception of time cease.

The shortest (quantum) unit of time possible is just that interval below which no possible change can happen. In other words, even the quickest ever possible change one can imagine takes an absolute minimum amount of time.

Change also implies there must be causality – there must be a cause that produces an effect, or in other words, something is affected by something else that occurred previously. Going from cause to effect implies a change and a time interval must have taken place into which that change fits. This introduces the commonly used phrase ‘arrow of time’. If time is our perception of change, then what is the ‘arrow of time’? Methinks it’s the reality that on the macro scale at least change happens only in one direction – cause precedes effect; effect follows cause, and that’s change. Examples of such one way cause and effect change include dropping the china cup and it breaks. A broken cup does assemble itself and then leap off the floor into your hand. Humans tend to be conceived, get born, grow up and age. Hair turns gray (or falls out), you get wrinkles and liver spots, and you die. You don’t rise from the grave, re-animate, and age backwards towards childhood and pop back into the womb! A hot cup of coffee cools off to room temperature. A cold cup of coffee doesn’t heat up by itself; even if there’s potential energy enough in the environment (air molecules flying around) to theoretically heat it up.  In other words, you can’t unscramble (or un-boil) an egg. 

Further readings about time:

Lockwood, Michael; The Labyrinth of Time: Introducing the Universe; Oxford University Press, Oxford; 2005:

PRESENT TIME: THE CONCEPT OF ‘NOW’: Does the present actually exist? We speak of it was if it does. But does it? Now I’m sure there’s no debating that there is a past, and that there will be a future. I’m sure there’s no debating that five years ago exists in the past; five years on from when you read this is clearly the future. What about five months ago, or ahead?  What about five days or five hours or five seconds? Is half a second ago the past? Is half a second hence the future? Of course it is. In fact, I suggest you can split units of time ever shorter and shorter, but still admit that ‘ago’ means past; hence means future, even if 0.000005 of a second ago really is past, and 0.000005 of a second hence is the future. So where comes the ‘now’ or the present?

While there is a past, and will be a future, there really does exist a present. There apparently is such a thing as the shortest interval of time and nothing shorter can exist in reality. That shortest interval of time is known as Planck-Wheeler time, below which time as we know it ceases to exist. It’s about 10 to the minus 43^rd of a second. That’s how long your present lasts for! One Planck-Wheeler time unit behind you is now forever locked in as part of your unalterable past. One Planck-Wheeler time unit ahead, is still part of your malleable (free will?) future.

Even without resorting to quite such a tiny present, physics logic suggests that you really are an isolated individual that cannot share the present with the rest of the world. Lets imagine this couple, say we call them Clive and Jane, sitting down for their evening meal. Clive says to Jane, “pass the salt please darling”. Now Clive utters that phrase in his present and Jane hears it in her present. But both presents aren’t simultaneous. When Jane hears it in her present, it’s simultaneously Clive’s past because it takes time for sound to travel from voice to ear (and light from mouth to eye). Actually, when Jane hears the word “salt”, “pass the” is already in her past while “please darling” is still in her future. In other words, Clive and Jane can’t ever share the same present even though both pass through identical simultaneously now’s.

Here’s a form of time travel. When Jane looks in a mirror, the image she sees in her present is actually of herself from her past – an ever so slightly younger version of herself because it takes an interval of time for the light to be reflected off Jane, onto the mirror, reflected off that, and back to Jane’s eyes.

In summary, nothing you see or hear has the exact same reality that you perceive in your present because there has been a time lag and things change over time – even incredibly short intervals of time. A common example is looking at a distant star. The star you see in you’re here and now isn’t the same star that exists in that same here and now. You’re looking at a star, which, for all you know, just may no longer exist!

Of course you do live your entire life in the actual ‘now’ – you certainly don’t literally live in any part of your past nor your future. Your life, your lifetime of ‘now’, is a string of Planck-Wheeler time units.

To be continued…

Electron-ness: Why Are All Electrons Identical? Part Two

INTRODUCTION: Individual members of the fundamental or elementary particles are absolutely identical with one another. In a police identification line-up, you couldn’t tell them apart. Why? Rather than go into an exhaustive review of the entire particle zoo, I’ll just hit on the electron and its antimatter mirror twin, the positron.

Continued from yesterday’s blog…

There is no violation of physical laws at the micro level in travelling through time (apart from going forward at a rate of one second per second which we do whether we like it or not), no exact causality mechanism has been proposed to explain how and why an elementary particle shifts gear into time reverse (or forward again). But, this is interesting, this time travel bit, so let’s explore it in some greater detail.

I’ll poor water on this fire at the outset by stating that time is but an illusion. Time doesn’t exist; therefore time travel** isn’t possible. Time is but a label and has no more reality than the label ‘Wednesday’. We just arbitrarily call every 7^th ‘day’ Wednesday, but you can no more hold Wednesday in your hands and you can time. Time has no independent reality. You can’t assign any physical properties to the concept. I mean time isn’t a solid, it isn’t a liquid, and it isn’t a gas. Time has no size, weight, colour, texture, density, it doesn’t vibrate or have a wavelength, ditto no odour or flavour, it has no temperature or pressure, it doesn’t consist of any known combination of known forces and/or elementary particles, it corresponds to no known element or compound. You can’t pour time into a bottle and store it; you can’t confine time in a force field or in a prison cell or trap it on a piece of sticky fly paper. Therefore, if time has no substance, one can not actually travel through time. Our sole electron (or positron) isn’t going anywhere – in time at least.

What we perceive as ‘time’ is nothing but change – change in our environment; in our natural world; in our mechanical devices; and even in ourselves and associated companions (animal and human). Repeat – time is but an illusion. Change is real since it involves forces and particles; energy and matter, the sorts of things that when you kick them, they kick back. We measure ‘time’ by the rate things change; rate of change is what we call ‘time’. Repeat - it’s the change (in something) that is real. 

Now on the macro scale, that is scales we interact with on a day-to-day basis, change appears to all intents and purposes to go one way (usually from a state or high order to a state of disorder) and so we view time as flowing from past to present to future – in one direction; order to disorder – past to present to future. But change in just one direction (order to disorder – past to present to future) is ultimately a function of numbers and probability. The simple illustration is to introduce a drop of ink into a bowl of water. That’s a high order situation. Now left to itself, there will be a change. The ink will disperse throughout the bowl of water. That’s a state of disorder. If a disordered uniform mix of ink and water separated all by itself into a drop of pure ink and a bowl of pure water (high order), that too is change, but we would interpret or view such an event as going backwards in time. If you viewed such a happening on film, you’d immediately conclude the film was being run backwards.

There’s a far greater probability for individual ink particles to spread out throughout a large volume than to come together in a small space. There’s lots of pathways to spread out; far fewer pathways to come together. But at the micro level, the level at which those individual ink particles do their thing, they don’t care where in the bowl of water they are. They are just as ‘happy’ to be all together as a drop of ink, as dispersed and diluted. If they do come together as a drop of ink from a dispersed/diluted state, that’s statistically unlikely, but such an event violates no laws of physics. It would be going from a state of maximum disorder to a highly ordered state; or, from an apparent future to present to past ordering. Such a change would appear for all practical purposes as apparent time travel – going backwards in time.

The catch – there’s always a catch – is while all those ink particles are defying statistical probability and undergoing apparent time-reversal, the rest of the cosmos is acting in a statistically normal way – going forward in ‘time’. So, perhaps we have a Universe where for 99.9999% of the time, 99.9999% of events within the Universe march to the beat of the standard past – present – future ordering of things. That is, in terms of change happening in a statistically probable way. While now and again tiny pockets of the Universe reverse direction, they do so at least just temporarily.  One can only defy statistically probability for only so long. So the ink particles come back together again as a drop of ink within a bowl of water – then what? They no doubt reverse direction again and proceed normally.

An analogy might be that while some individuals are winners while playing the slot machines (high order), the club still rakes in the profits from the vastly greater majority of (disordered) losers, and that no doubt the few highly ordered winners will eventually descend into a state of disorder and contribute ultimately to the club’s profit margin! It’s more statistically likely for a winner to become a loser than for a loser to become a winner.

Back to electrons, on average, any given electron has a very high probability of participating in a changing set of circumstances consistent with statistically probability. That is, the electron is moving forward in ‘time’. But if in those rare (loser to winner) occasions the changing set of circumstances goes against the grain of statistically probability, then we would view that electron as moving backwards in ‘time’. But there ultimately is no backwards or forwards in time, just change which statistically goes or moves in one general direction (order to disorder), but which can now and again, and briefly, go the reverse direction (disorder to order).

To belabour the point, what we call the past is change which has already happened; the present is change which is happening; the future is change that will happen.

The question remains, can you revisit and experience a past event? Can there be an instant (or not so instant) replay? Take the example of the now dispersed ink in the bowl of water. If all the ink bits (particles) were to exactly retrace their movements (that’s just so highly improbable that you’d wait longer than the age of our Universe to actually see it), they would eventually come together as an ink drop. If they now retrace those retraced movements (ditto on the statistical improbability) you get back to the exact same configuration of dispersed ink bits in the bowl of water. You will have witnessed an instant (or not so instant) replay of a past event. You would have in a sense travelled back in time to record an event that had already happened. Of course you would have ‘time’ travelled with respect to that specific event and only that event.

Ah, that word ‘record’. Of course you could have filmed the original ink drop to dispersed ink event then watched the film at a later date, but that’s cheating a bit, don’t you think?

Okay, all that was an aside – back to the original question, why are all electrons identical? Or not, as the case may be.

To be continued…

**Assuming for a moment that time is actually something tangible and that travel through it is possible (that’s in agreement with Einstein’s General Theory of Relativity). That aside, I’d maintain that travel backwards in time is probably nonsense.

If you go back in time with a view to either preventing something from happening or inaugurating something and you succeed, then when you return to your own present time the original motive to go back in time in the first place has ceased to exist. That’s because in your now altered present, there’s nothing motivating you to go back in time and so you don’t, but if you don’t then you couldn’t have changed the past in the first place. That actually suggests that your actions have split the Universe and generated two timelines (or universes), one in which you go back to fix something, and one in which you don’t because there’s nothing that needs fixing.

If you don’t succeed, if you can’t tamper with the past (akin to Stephen Hawking’s Chronology Protection Conjecture) then it’s all an exercise in futility and so there’s no point being a damn fool about it. If at first you don’t succeed, give up!

If you go back in time just to observe (as historian, scientist or even tourist), your very presence in the past has introduced a change that didn’t previously exist, and any change has a ripple effect which will change, even if only slightly, your own present, in you’re your before-the-fact time travelling present was different to your after-the-fact time travelling present, which could, as we’ll see, generate a paradox. You may not care about the alteration, but other people may not be so happy and laid back with your inadvertent meddling.

But wait a second. Those other people probably wouldn’t know or be aware that anything had altered. Having reset the clock when you went back in time, the ripples would have become part and parcel of their world view, so only you, upon your return (having bypassed all the rippling) would notice the change.

But what if you go back in time only to materialize in front of a speeding train and are killed. Of course that doesn’t affect your ancestors so presumably they still meet and marry and breed and ultimately your born – again – only to go back in time and get hit by that train!  

Or, you materialize back in time and so startling someone of that era into failing to notice that train and gets killed. Now say that someone was your father-to-be; your father before he met your mother. Now you have two universes – timelines – again. One timeline is where you went back in time and presumably returned; one in which you were never born.

Here’s another time travelling curve ball coming your way. You have a set of coordinates with respect to Planet Earth – latitude, longitude, and altitude. But you also have a set of coordinates with respect to the Moon – lunar latitude, longitude and altitude. You have a set of coordinates with respect to the Sun (solar latitude, longitude and altitude). Ditto Mars, and ditto the nearest star and ditto the centre of the Milky Way Galaxy, etc. In fact, although they change from moment because of relative motions of all the bodies concerned (that also applies to you and Planet Earth since you move around), you have a set of coordinates with respect to every bit of matter in the Universe. The question is, when you time travel, what set of coordinates do you take with you? Where exactly do you end up? It’s taken for granted in works of fiction that its Earth’s coordinates, but is it necessarily so? What if you retain your exact position (relative to where exactly is a mystery) but travel in time. Then presumably when you materialize else-when, the Earth will have moved far away, and there you are flailing around in empty space, breathing a deep vacuum!

So we see that while time travel stories are a staple of the sci-fi authors’ bag-of-tricks – they stir up those little grey cells – there doesn’t appear to be much chance of time travel in any physical reality we know of. Time travel is only a reality in the imagination. We in fact have a version of the Fermi Paradox here. While that referred to aliens knocking on our collective doors, if time travel were possible, then where are all those time travelling tourists from our future?