How 'big' is our present time?
Time can be divided three ways
Time in the future
Time in the present
Time in the past
We are living in the 'present'.
My question: how 'big' is this present time?
It might help if you think of a pen placed on a white sheet of paper. The pen represents our present time. The white space above the pen is the future, below is the past.
So how 'big' is the present time?
i.e. is it 0.0000000000000001 seconds
or even 0.00000.... infinitesimally small?
Does anyone have any input?
Thanks.
Time in the future
Time in the present
Time in the past
We are living in the 'present'.
My question: how 'big' is this present time?
It might help if you think of a pen placed on a white sheet of paper. The pen represents our present time. The white space above the pen is the future, below is the past.
So how 'big' is the present time?
i.e. is it 0.0000000000000001 seconds
or even 0.00000.... infinitesimally small?
Does anyone have any input?
Thanks.
Comments (33)
In other words, what is the smallest amount of present time that can exist in order to differentiate the past and future?
In atomic engineering terms it is very small - a trillionth of a second? As to what the limits are...some say time itself is ultimately granular and discrete.
Past, present and future describe different present moments to different observers, depending on their relative speed and position in space/time (thanks Einstein).
Let's boil it down to present-then and present-now.
It rained on Tuesday = present-then (past).
It is raining = present-now.
It will rain on Tuesday = present-then (future).
Perhaps the subjective present moment is not 'static' as your analogy suggests but dynamic and continuous, since, according to this premise, time is a unidirectional linear collection of present moments (at least to the observer).
The subjective present therefore doesn't have a 'size' objectively, as it's experience differs for each observer.
If there exists an 'objective present', where present moment is one continuous thing rather than discrete portions of the whole, then it's size would logically be all of space and time... I think.
Time has a physical limit in that nothing could happen in less than the Planck time - 10^-44 seconds.
But then even physically to differentiate past and future gets complicated. You would have to start factoring in the time it takes light to travel and so bring news of a difference. It takes about 8 minutes for the light (and gravity) of the sun to affect the earth. So if the sun went supernova, our present wouldn't change until 8 minutes later.
Then if you are talking about psychological time, it takes about half a second to consciously integrate a change and so update our running image of "the present".
We don't really notice that processing lag because we can respond to quite complex events in a faster habitual fashion within a fifth of a second. And what smooths out our experience of "the present" even more is that we build an anticipatory sensory expectation ahead of every coming moment. So half a second out, we are already forming a prediction of what "the present" should feel like.
For instance, we know we are about to turn our head to look towards something. So already we are subtracting away the motion to our view that we are about to cause - it feels like we are turning rather than that the world is spinning. And we have an expectation of the general scene we should discover due to our familiarity through memory.
So the psychological present moment is not some instant snapshot deal but a complex neural construction that starts by us "peering into the future" and then "working out a settled interpretation of what just happened". It spreads itself out over at least a second and then "the present" is however it washed up according to our memory.
The smallest temporal discrimination we can make is much finer grain - down to 20ths of a second for sharp onset/offset stimuli where we are focused and know what to expect. Attention can do "post-processing" to identify a particular brief signal, but at the expense of then losing sight of whatever else was going on in that half second or so "frame".
A good example of just how grainy our time perception actually is, and how much it is dependent on interpretation or expectation, is the cutaneous rabbit experiment - https://en.wikipedia.org/wiki/Cutaneous_rabbit_illusion
I suspect the present is about as big as 'here' is in size.
2) The present is the past pressing forward. There is no way to separate them from each other since time is continuous and indivisible.
The present is a pretty big gift.
But... does it fit in Santa's sleigh?..
I opine that existential time is not a mathematical continuum. If it were, then the present would have 'measure zero.' But then how could you read this sentence? Note how the meaning of the beginning blends with an anticipation of the meaning to come. Physics time is not human or existential or lived time. For us the future dominates, wearing a dress made from the rags of the past. Through us the future carves up the present. This body is the tool through which space is carved into the shape of a desired future. And this still-being-born future has a shape influenced by the past from memory. Just think of our inherited language. We name ourselves and what ought to be in a tongue we did not choose, in a tongue that developed over generations of suffering and insight.
I've got to admit, Santa's been alive for a good two-hundred years, maybe more.
The only sufficient explanation is that he can regenerate, so he must be a time-lord.
Instead of a sonic screwdriver maybe he's got a sonic slingshot so he can deliver presents through people's chimneys??
It's all hypothetical at this point.
Specious time, that is, the minimal unit of conscious time in which an event can be said to be perceived naturally as present, is between 2 to 5 milliseconds. This is associated with the oscillatory movements of cells in the upper cortex.
From observation one can say that we experience changes in memory that feels like personal (psychological) time (duration). This is the time we experience. Since it is all memory, we can call it what we will but most c specifically it is there sense of memory evolving.
Indeed. Well said. And this is naked for whomever just looks.
Quoting ff0
Back to Zeno. At any particular instant the arrow is at rest. How then can it move?
I agree with you that the mathematical continuum is not an accurate model of the nature of the real world. What's interesting is that physicists are trained to think of an instant of time as a real number t. What's the acceleration at time t, what's the temperature?
The math helps them to craft interesting theories. But the world is definitely not the same as the mathematical real line. The world is not a set of dimensionless points of space and instants of time.
Right. The theoretical picture of nature reminds me of a grid that's loosely projected on an everyday experience of just being in the world with furniture and other people. I agree that this grid is not the thing itself. I'd also stress that even the objectively real is something that has to be filtered out of tangled personal experience. We basically scrub everything personal away. In fact we have mortal being with particular faces and sense organs and histories, etc., experiencing things. But (for good reason) blend and filter such experience into an image of the object, the public. This kind of thing probably goes even deeper, to the use of words like 'experience' and language in general. We pretend/assume that 'experience' has a fixed, universal meaning, etc. As others have said, we project being on becoming. But that's no final statement either. 'Fail again. Fail better....Till nohow on.'
I guess the present or any division of time for that matter has to be meaningful. Read this way then, as other posters have said, the present is the time length necessary for us to perceive changes in our world.
Another way of looking at it would be the smallest length of time that can be measured. @apokrisis says that the smallest unit of time is the planck time (about 10^-44 seconds). I'm guessing here but I think that's the smallest time period of the fastest repetitive phenomena in the universe. We can't measure time smaller than 10^-44 seconds or perhaps no physical change can occur faster than the planck time.
Traditionally we understand it to be an instant, or duration-less (as someone like Augustine would say, it's like a knife edge separating the past and future). However, some people would venture to say that the present has some extension to it and that what currently exists is more than an instant but still very short. If you take the idea to the extreme, you have the block universe, where all moments exist. Take it back a notch and you have the growing block universe, which is smaller but it would still be pretty big.
There is also the specious present, the present that figures in our perception, which is a little bit bigger than an instant but that all depends upon our brain processes. Relativity also talks about simultaneity, which refers to the way we order events in spacetime, where we could call the "now" we live on the set of events in which are simultaneous to us. However, I imagine that that is not what you are looking for.
Personally, I don't think that there is such a thing as a present "moment" or "time" at all, so questions about its duration are meaningless. You don't need times or moments in order for things to change.
Isn't the past/present/future thing a bit artificial?
What we call the present--Isn't it really just the recent past and immediate future? No point trying to quantify its duration, as if it were a real distinct division into actual different periods..
Michael Ossipoff
If you take the question to be about the maximum rate of change, then it makes sense.
So the present is commonly understood as the extent of the moment between the past and future. It is the instant when everything actually "exists" in some non-changed fashion. Things are momentarily fixed, suspended between a past that is some evolving history that is the causes of the events happening in the present, and the future where there are further possible changes, but those have yet to be actualised.
The present is thus our measure of actualisation or realisation. And it is imagined as being rather statically existent. There is a duration in which the actual is what is, and nothing else is changing. Then this actuality gets swept out of the present and into history once it itself becomes a cause of further actualities, the cause of further possibilities becoming realised.
So the question is really about how long does actuality endure in that present tense gap between first becoming stably real as an effect, a crystalisation of what had been a future possibility, and then stably real as itself a cause, or the now historic reason for further actualities.
Hierarchy theorist Stan Salthe dubs this the "cogent moment". Henri Bergson had a similar idea.
If the world is understood in terms of a hierarchy of processes, then they all will have their own characteristic integration times. Time for the Cosmos is not some Newtonian dimension. It is an emergent feature of being a process as every process will have a rate at which it moves from being just starting to form a settled state - reaching some sort of cogent equilibrium which defines it as having "happened" - and then being in fact settled enough to become the departure point, the cause, for further acts of integration or equilibration.
So this view of time sees it not as a spatial line to be divided in two - past and future - with the present being some instant or zero-d point marking a separation. Instead, time is an emergent product of how long it takes causes to become effects that are then able to be causes. For every kind of process, there is going to be a characteristic duration when it comes to how long it takes for integration or equilibration to occur across the span of the activity in question.
We can appreciate this in speeded up film of landscapes in which clouds or glaciers now look to flow like rivers. What seemed like static objects - changing too slowly to make a difference to our impatient eye - now turn into fluid processes. They looked like chunks of history. Now we see them as things very much still in the middle of their actualisation. They will be history only after they have passed, either massing and dropping their rain, or melting and leaving behind great trenches etched in the countryside.
So the present is our intuitive account of the fact that causes must be separated from their effects, and the effects then separated from what they might then cause. There is some kind of causal turnaround time or duration - a momentary suspension of change - that is going to be a physical characteristic of every real world process. Thus there is some rate of change, some further "time frame" or cogent moment, that gets associated with every kind of natural system.
At the level of fundamental physics, this turns out to be the Planckscale limit. Time gets "grainy" at around 10^-44 seconds. The Planck distance is 10^-35m. So the Planck time represents the maximum action that can be packed into such a tiny space - the single beat of a wavelength. That primal act of integrated change - a single oscillation - then also defines the maximum possible energy density, as the shortest wavelength is the highest frequency, and the highest frequency is the hottest possible radiation.
So the shortest time, the smallest space, and the most energetic event, all define each other in a neat little package. Actuality is based on the rate at which a thermal event can come together and count as a "first happening" - a concrete Big Bang act of starting to cool and expand enough to stand as a first moment in a cosmic thermal history.
Then psychological time for us humans is all about neural integration speed. It takes time for nerve signals to move about. The maximum conduction speed in a well-insulated nerve, like the ones connecting your foot to your brain is about 240 mph. But inside the brain, speeds can slow to a 20 mph crawl. To form the kind of whole brain integrated states needed by attentional awareness involves developing a collective state - a "resonance" - that can take up to half a second because of all the spread-out activity to become fully synchronised.
So there is a characteristic duration for the time it takes for causes to become the effects that are then themselves causes. Input takes time to process and become the outputs that drive further behaviour. Which is why I mention also the importance of bridging this processing gap by anticipation. The brain shortcuts itself as much as it can by creating a running expectation of the future. It produces an output before the input so that it can just very quickly ignore the arriving information - treat it as "already seen". It is only the bit that is surprising that then takes that further split second to register and get your head around.
But between this physical Planckscale integration time and this neural human information processing time are a whole host of other characteristic timescales for the processes of nature.
Geology has its own extremely long "present tense". Stresses and strains can slowly build for decades or centuries before suddenly relaxing in abrupt events like earthquakes or volcanoes.
Here is a good visual chart of the integration time issue in biology - http://www.cell.com/cell/pdf/S0092-8674(16)30208-2.pdf?_returnURL=http%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0092867416302082%3Fshowall%3Dtrue
The philosophy of time is still very much hung up on the old Newtonian model, where time is some global spatialised dimension, and St Augustine's psychological model of time, where it is now somehow all a subjectively-projected illusion.
There is some truth in both these views. The brain does have to construct duration. The Cosmos does have a characteristic global rate in terms of its thermal relaxation - the one described by c as a Planck constant.
But a process view explains time in a more general fashion by relating it to the causal structure of events. Every system has some characteristic rate of change. There is a cogent moment graininess or scale created by the fact that not everything can be integrated all at once. It requires "time" to go from being caused to being a cause. There is a real transition involved. And that happens within what we normally regard as the frozen instant when things are instead finally just "actual". That is, brutely existent and lacking change, not being in fact a transition from being caused to being a cause in terms of our multi-scale accounts of causal flows.