People often ask whether we’re subject to changes in time that someone else has initiated but where we’re none the wiser. The idea of time ripples which propagate changes from the past into the future is one attempt which attempts to dispel this idea because when those ripples reach the present we notice the change.
I recently watched “The Sound of Thunder” – the movie version of Ray Bradbury’s short story of the same name. The long and short of it is that someone steps on and kills a butterfly in prehistoric times and comes back to the present to find that it’s been dramatically altered.
An idea is presented in the movie where a change in the past causes ripples in time into the future – these are readjustments to climate, nature, evolution etc. and which of course cause a few problems for our beloved main characters.
Time behaving as a fluid, whether it be as the famous River of Time, or something more like a vast lake isn’t a new idea, but I thought that the idea of ramifications extending from past to present not as an instantaneous change but as a time varying progression to be an interesting one!
In the movie there isn’t just one time ripple, but a series of ripples. Each ripple lasts a few moments, and where in true Hollywood style we see a wall of blurry skyline hurtling (through space) towards the camera and bringing with it various changes. There’s a pause, and then the next ripple hits.
Of course in the movie, the final ripple is the one which will knock out the humans and is the clinch point of the movie – the nail-biter and the source of tension.
An interesting idea…but there’s a flaw.
Here’s the thing about the ripples. The first is fairly obvious and I’ve already mentioned it: the ripples are seen to move over space and not time. We see the wave moving (i.e. it has a speed – distance divided by time) so it’s moving within time, and not across it. But I’ll give over to this and put it down to Hollywood dumbing down and dramatics.
For me the main issue is the wave dispersion principle. Stand on the shore of a river and listen to the waves lapping the shore after a boat passes. At first the waves are large and slow, and as time goes on the waves become smaller, but quicker. The wave dispersion principle: that waves with smaller wavelengths and wave heights travel slower than larger waves.
Exactly the opposite happens with the time waves in this movie which get bigger and further apart…
Water waves and time waves
Is it fair to assume a direct similarity between time waves and water waves?
Time behaving as a river or some other mass collection of some sort of fluid is only a model or souped up ( 😉 ) analogy. It may seem to hold true in some areas more than in others (as is the case with many models) – but it does afford us the chance to explore some “what if” scenarios.
Peaks and troughs
Waves are most noticeable by their peaks – a fact given over even to the measurement of waves – the “significant wave height” for example, which is defined as the mean wave height of the highest third of the waves. We use the highest third because the human eye is predisposed to preferentially see these – just as it’s easier to see the peak of a wave than its trough. A fact attested to by the fact that we see the peaks of the time waves in the movie, and nothing else.
(Actually, there are energetic arguments too; that small changes in increasing wave height give large amount of additional energy – but the above point still holds!)
The time wave, if really a wave, would consist of a peak (as seen in the movie) and a trough (which isn’t seen in the movie).
This got me thinking about another possible scenarios which could have played through – that readjustment might also happen in the troughs.
What would this mean?
Different parts of a wave move its medium in different directions. The peak moves forwards (e.g. a surfer on or just in front of the peak is pushed forwards by the water underneath his board). With the trough the reverse is true – there is movement backwards.
So in other words, if a temporal readjustment were to happen in the troughs, we’d regress into…actually, I don’t know what! (And given wave asymmetry, it’s also likely that we’d spend a longer period of time in readjustment in the trough…especially given the Hollywood induced longer wavelength!)
Wave orbital motion
Additionally, if we look more closely at the motion under a wave, fluid dynamics dictates that there is no net movement (aside from a little “Stoke’s Drift”); the forward motion at the peak is countered by the reverse motion in the trough. Actually there’s also equal and opposing vertical motion on the leading and trailing sides of the wave too.
This makes sense – throw a pebble into a pond and the waves emanate from the epicenter – but all the water doesn’t move away from the location where the pebble landed; there’s no gaping hole left in the middle of the pond. (Although if you drop a meteorite in the middle of the Jurassic Period wiping out the dinosaurs, then certainly a crater is left…! 😉 )
So no net motion means no net change – no readjustment. Time ripples used as a chronic temporal readjustment can’t work…
The idea then, that we’re made aware of changes in the past through some sort of chronic time ripple doesn’t seem to hold much weight. Or is there just nothing? No waves, ‘just’ the creation of a new time line? Or to extend the analogy, the creation of a new pond?
Who’s to know? This is always been the argument.
The time ripple idea often seems to assume a rapid change, but by the arguments given above it is also likely that we might be in a prolonged readjustment period. One which happens so slowly that it’s imperceptible. Maybe it happens so slowly that it actually happens in real time – in other words – we create our own future.
Now how awesome is that!